Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Technology Evaluation Center CYP2D6 Pharmacogenomics of Tamoxifen Treatment Assessment Program Volume 28, No. 8 January 2014 Executive Summary Background Tamoxifen is prescribed as a component of adjuvant endocrine therapy to prevent hormone receptorpositive breast cancer recurrence, as treatment of metastatic breast cancer, and to prevent disease in high-risk populations and in women with ductal carcinoma in situ. The cytochrome P450 2D6 (CYP2D6) metabolic enzyme has a major role in tamoxifen metabolism. The CYP2D6 gene is polymorphic; variant DNA gene sequences resulting in proteins with markedly reduced or absent enzyme function may be associated with lower plasma levels of active tamoxifen metabolites, particularly endoxifen, which is predominantly dependent on CYP2D6 for its production, and are thus hypothesized to have an impact on tamoxifen treatment efficacy. Patients who have little or no CYP2D6 enzyme function are called poor metabolizers (PMs) compared with patients with 2 fully functional alleles, termed wild-type or extensive metabolizers (EMs). Those with enzyme activity in between are called intermediate metabolizers. Objective This Assessment evaluates the evidence for CYP2D6 genotyping, compared with no testing, to direct treatment regimen choices for patients at high risk for primary breast cancer or breast cancer recurrence, and to improve survival outcomes. Search Strategy MEDLINE® was searched (via PubMed) using the search string (“Breast Neoplasms”[MeSH®] AND “Tamoxifen”[MeSH®]) AND “Cytochrome P-450 Enzyme System”[MeSH®] through November 2013. Clinical trials, recent reviews (2008-2013), editorials, and letters related to the pharmacogenomics of tamoxifen were retrieved. Text and reference lists of retrieved articles were examined for additional relevant articles. ® ® BlueCross BlueShield Association An Association of Independent Blue Cross and Blue Shield Plans Selection Criteria Full-length, peer-reviewed publications reporting studies of postmenopausal women undergoing endocrine therapy whose treatment regimen selection is based on CYP2D6 genotyping versus usual selection methods or studies of the association of CYP2D6 genotype with intermediate (e.g., tamoxifen-active metabolite levels) or final outcomes (e.g., time to recurrence, survival) were selected for review. Studies were assessed for potential bias, such as survival bias (genotyping whole blood from surviving participants of retrospective studies); misclassification of metabolizer phenotype; and adjustment for variables not considered confounders of the genotype-outcome association. Main Results One U.S. Food and Drug Administration-cleared test for CYP2D6 genotyping has consistent evidence of analytic validity (i.e., technical accuracy and reliability). NOTICE OF PURPOSE: TEC Assessments are scientific opinions, provided solely for informational purposes. TEC Assessments should not be construed to suggest that the Blue Cross Blue Shield Association, Kaiser Permanente Medical Care Program or the TEC Program recommends, advocates, requires, encourages, or discourages any particular treatment, procedure, or service; any particular course of treatment, procedure, or service; or the payment or non-payment of the technology or technologies evaluated. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. 1 Technology Evaluation Center There is a chain of evidence and direct evidence for clinical validity (i.e., association of CYP2D6 genotype with drug efficacy). The chain of evidence associates an intermediate outcome, tamoxifen metabolite plasma levels, with both CYP2D6 genotype and health outcomes (recurrence, survival) in women treated with tamoxifen. Direct evidence compares outcomes in women treated with tamoxifen or other endocrine therapy stratified by metabolizer status. Chain of Evidence n Association of genotype with plasma levels of active tamoxifen metabolites: Five prospective cohort studies of adjuvant tamoxifen treatment provide consistent evidence that CYP2D6 nonfunctional variant alleles are associated with significantly reduced plasma endoxifen levels. However, endoxifen levels overlap across all genotypes, indicating that CYP2D6 genetic variability only partly explains endoxifen level variability. Although generation of 4-hydroxy tamoxifen (4-OH tamoxifen), another active tamoxifen metabolite, does not depend solely on CYP2D6, 3 of 4 studies showed that low CYP2D6 function was associated with reduced plasma 4-OH tamoxifen levels. Coadministration of potent CYP2D6 inhibitors to CYP2D6 homozygous wild-type patients is associated with endoxifen levels near those of patients who are PMs. n Association of in vivo endoxifen levels with clinical outcomes: Two studies examined the relationship between CYP2D6 genotype and active tamoxifen metabolites, and between genotype and clinical outcomes in the same patient population. Both studies enrolled patients from Asian populations, focusing almost exclusively on the prevalent reduced-function CYP2D6*10 variant in this population. Both studies reported reduced endoxifen and/or 4-OH tamoxifen concentrations in patients homozygous or heterozygous for variant alleles, and in conjunction reported decreased disease- or recurrence-free survival. One or both studies have design flaws likely resulting in selection bias. In addition both studies are small, resulting in estimates of association with wide confidence intervals. Thus, the relationship between endoxifen (or 4-OH tamoxifen) plasma concentrations and clinical outcomes has not been established in Asian populations, nor has it been studied in white populations with null function CYP2D6 genotypes. Direct Evidence Association of genotype with clinical outcomes: One group* directly compared tamoxifen-treated women with those clinically eligible for but not receiving tamoxifen, stratified by CYP2D6 genotype. This retrospective study used archived tumor samples from a randomized controlled trial of tamoxifen treatment in the adjuvant setting. Investigators found that tamoxifen-treated EMs obtained no significant clinical benefit compared with EMs not treated with tamoxifen, and, paradoxically, that carriers of a CYP2D6*4 nonfunctional variant allele benefited from tamoxifen treatment. There were several limitations to this study such that results are questionable. Most included studies examined tamoxifen use in the adjuvant setting in postmenopausal women. Most enrolled only tamoxifen-treated women and evaluated outcomes by CYP2D6 genotype. A few separately evaluated a non-tamoxifen-treated control population but without direct comparison. Seven small studies in Asian populations focused on the CYP2D6*10 reduced function allele; 4 reported significant results for the association of CYP2D6 genotype with outcomes of tamoxifen treatment, but may be affected in unpredictable ways by different types of bias (survival bias and adjustment for variables that are not confounders). Two of the 3 studies that reported no association may have less potential for bias. Sixteen studies evaluated samples from primarily white patients. Of the 5 largest studies, 3 reported no significant association between CYP2D6 reduced or null activity genotype and time to breast cancer recurrence. Two of the negative studies were retrospective analyses of clinical trial samples and one was a matched case-control study nested within a well-documented breast cancer registry. All 3 were designed to minimize the potential for bias; their sizes allowed comparison of homozygous nonfunctional CYP2D6 genotypes (PMs) with fully functional wild-type genotypes (EMs), that is, the most extreme comparison and most likely * Wegman P, Vainikka L, Stal O et al. (2005). Genotype of metabolic enzymes and the benefit of tamoxifen in postmenopausal breast cancer patients. Breast Cancer Res, 7(3):R284-90. 2 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment to reveal a true association. Two studies reported significant positive results; 1 study combined samples from different sources, some of which had already been analyzed for this hypothesis. In addition, it is unclear from the report whether nearly half of the samples were obtained from patients who had survived and were available at a time distant from their diagnosis and surgery, a survivorship selection bias that can unpredictably affect results. The other positive study matched samples from a randomized controlled trial on several breast cancer prognostic variables, neither causally related to CYP2D6 genotype nor surrogates for genotype, potentially biasing selection of cases and controls. The remaining 9 studies report a variety of significant and nonsignificant results; no pattern of bias, genotyping or group scheme, or accounting for CYP2D6 inhibitor use (among possibilities) explains the differences in results. Heterogeneity of results across all studies, and clear results of no genotype-tamoxifen treatment outcome in 2 large trials with the least apparent potential for bias, suggest lack of support for clinical validity. There is no direct evidence of clinical utility (whether use of CYP2D6 genotype testing for endocrine therapy regimen selection improves recurrence and survival outcomes). Without demonstrable clinical validity, there is no basis for changing management in patients with specific genotypes to improve outcomes (clinical utility). Author’s Conclusions and Comments The question examined in this Assessment is whether patients with CYP2D6 gene variants that result in markedly reduced or absent enzyme function have reduced tamoxifen metabolism and lower endoxifen levels compared with genotypic wild-type extensive metabolizers, and as a result have poorer clinical outcomes. This question rests on the assumption, not yet supported by evidence, that some level of endoxifen is sufficient and necessary for tamoxifen efficacy, and that this level is not achieved in patients with markedly reduced or no CYP2D6 enzymatic function. However, because tamoxifen metabolism is complex and CYP2D6 does not appear to account for all variability in endoxifen levels, it is conceivable that polymorphisms in other tamoxifen metabolic pathway enzymes may affect active metabolite levels, and in theory direct measurement of the metabolite(s) itself might be the better predictor of benefit from tamoxifen treatment. However, measuring metabolite levels is not practical for clinical applications. Whether lower endoxifen levels can affect the pharmacodynamics of tamoxifen, the interaction of tamoxifen metabolites with estrogen receptors, and ultimately tamoxifen efficacy, is unclear. Dissociation constants of even the more weakly binding molecules, including tamoxifen itself, are reportedly still sufficient to effectively block estrogen binding. Moreover, it is estimated that at doses used for adjuvant treatment, which are intended to saturate the estrogen receptor, more than 99% of estrogen receptors are bound by tamoxifen and its metabolites. Lacking the appropriate mechanistic evidence, it remains to examine the clinical evidence, the bulk of which addresses clinical validity, the CYP2D6 genotype-tamoxifen treatment outcome association. As noted, heterogeneous results are observed across studies. Heterogeneity in effect estimates, both in magnitude and significance, is likely due to the lack of power in most studies and potential biases. The analysis of archived samples from 2 large completed clinical trials was undertaken to achieve adequate power, to more fully evaluate CYP2D6 genotype, to evaluate aromatase inhibitor-treated control populations in tandem, and to avoid potential sources of bias. That the results of these studies discovered no evidence of association between CYP2D6 genotype and either tamoxifen- or aromatase inhibitor-treated patient outcomes has suggested that using results of CYP2D6 genetic testing to influence decisions about tamoxifen treatment is not currently warranted. Based on the available evidence, the Blue Cross and Blue Shield Association Medical Advisory Panel made the following judgments about whether CYP2D6 genotyping for directing endocrine therapy regimen selection for women at high risk for primary breast cancer or breast cancer recurrence meets the Blue Cross and Blue Shield Association Technology Evaluation Center (TEC) criteria. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.3 Technology Evaluation Center 1. The technology must have final approval from the appropriate governmental regulatory bodies. The Roche AmpliChip CYP450 Test is cleared by the U.S. Food and Drug Administration (FDA) and is “intended to identify a patient’s CYP2D6 and CYP2C19 genotype from genomic DNA extracted from a whole blood specimen. Information about CYP2D6 and CYP2C19 genotype may be used as an aid to clinicians in determining therapeutic strategy and treatment dose for therapeutics that are metabolized by the CYP2D6 or CYP2C19 gene product” (http://molecular.roche.com/assays/ Pages/AmpliChipCYP450Test.aspx). CYP2D6 genotyping assays are also available as laboratory-developed tests (LDT). Clinical laboratories may develop and validate tests in-house and market them as a laboratory service; laboratories offering LDTs as a clinical service must meet the general regulatory standards of the Clinical Laboratory Improvement Act (CLIA) and must be licensed by CLIA for high-complexity testing. FDA has considered updating the label for tamoxifen (brand and generics) with information or recommendations regarding CYP2D6 genotyping and impact on tamoxifen efficacy. On October 18, 2006, FDA held an Advisory Committee meeting to answer specific questions regarding the evidence and recommendations for the label update. Since that Advisory Committee meeting, AstraZeneca, the brand name (Nolvadex®) manufacturer, has ceased producing tamoxifen and is no longer maintaining the prescribing information. As of the date of this Assessment, no direction has come from FDA regarding revised labeling of generic versions of tamoxifen to include CYP2D6 genotyping information. 2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes. There are several limitations to the overall body of evidence, but the largest, most well-designed studies do not support clinical validity of the test. In the absence of evidence for clinical validity, evidence to support clinical utility is lacking. 3. The technology must improve the net health outcome. Evidence for clinical utility is currently lacking. 4. The technology must be as beneficial as any established alternatives. Because the available evidence does not clearly support a significant association between CYP2D6 genotype and tamoxifen treatment outcome, a chain of evidence supporting the clinical utility of CYP2D6 genotyping for directing endocrine therapy regimen selection for women at high risk for or with breast cancer cannot be constructed. 5. The improvement must be attainable outside the investigational settings. The use of CYP2D6 genotyping for directing endocrine therapy regimen selection for women at high risk for or with breast cancer to improve health outcomes has not been demonstrated in the investigational setting. Based on the above, CYP2D6 genotyping does not meet the TEC criteria for directing endocrine therapy regimen selection for women at high risk for primary breast cancer or breast cancer recurrence. 4 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment Contents Assessment Objective 6 Background6 Methods12 Problem Formulation 13 Review of Evidence 14 Discussion32 Summary of Application of the Technology Evaluation Criteria 33 References35 Appendix39 Published in cooperation with Kaiser Foundation Health Plan and Southern California Permanente Medical Group. TEC Staff Contributors Author—Joan Glacy, M.D.; TEC Executive Director—Naomi Aronson, Ph.D.; TEC Director, Technology Assessments—Mark D. Grant, M.D., M.P.H.; Director, Clinical Science Services—Kathleen M. Ziegler, Pharm.D.; Research/Editorial Staff—Claudia J. Bonnell, B.S.N., M.L.S.; Kimberly L. Hines, M.S. Acknowledgment Staff would like to acknowledge the work of Margaret A. Piper, Ph.D., M.P.H., in the research and development of this Assessment. Blue Cross and Blue Shield Association Medical Advisory Panel Trent T. Haywood, M.D., J.D.—Chairman, Senior Vice President, Clinical Affairs/Medical Director, Blue Cross and Blue Shield Association; Steven N. Goodman, M.D., M.H.S., Ph.D.—Scientific Advisor, Dean for Clinical and Translational Research, Stanford University School of Medicine, Professor, Departments of Medicine, Health Research and Policy; Mark A. Hlatky, M.D.—Scientific Advisor, Professor of Health Research and Policy and of Medicine (Cardiovascular Medicine), Stanford University School of Medicine. Panel Members Peter C. Albertsen, M.D., Professor, Chief of Urology, and Residency Program Director, University of Connecticut Health Center; Sarah T. Corley, M.D., F.A.C.P., Chief Medical Officer, NexGen Healthcare Information Systems, Inc.—American College of Physicians Appointee; Helen Darling, M.A., President, National Business Group on Health; Josef E. Fischer, M.D., F.A.C.S., William V. McDermott Professor of Surgery, Harvard Medical School—American College of Surgeons Appointee; I. Craig Henderson, M.D., Adjunct Professor of Medicine, University of California, San Francisco; Jo Carol Hiatt, M.D., M.B.A., F.A.C.S., Chair, Inter-Regional New Technology Committee, Kaiser Permanente; Saira A. Jan, M.S., Pharm.D., Associate Clinical Professor, Ernest Mario School of Pharmacy, Rutgers, The State University of New Jersey, Residency Director and Director of Clinical Programs Pharmacy Management, Horizon Blue Cross and Blue Shield of New Jersey; Thomas Kowalski, R.Ph., Clinical Pharmacy Director, Blue Cross Blue Shield of Massachusetts; Lawrence Hong Lee, M.D., M.B.A., F.A.C.P., Vice President and Executive Medical Director for Quality and Provider Relations, Blue Cross and Blue Shield of Minnesota; Bernard Lo, M.D., Professor of Medicine and Director, Program in Medical Ethics, University of California, San Francisco; Randall E. Marcus, M.D., Charles H. Herndon Professor and Chairman, Department of Orthopaedic Surgery, Case Western Reserve University School of Medicine; Barbara J. McNeil, M.D., Ph.D., Ridley Watts Professor and Head of Health Care Policy, Harvard Medical School, Professor of Radiology, Brigham and Women’s Hospital; William R. Phillips, M.D., M.P.H., Clinical Professor of Family Medicine, University of Washington—American Academy of Family Physicians’ Appointee; Richard Rainey, M.D., Medical Director, Regence BlueShield of Idaho; Rita F. Redberg, M.D., M.Sc., F.A.C.C., Professor of Medicine and Director, Women’s Cardiovascular Services, University of California San Francisco; Maren T. Scheuner, M.D., M.P.H., F.A.C.M.G., Chief, Medical Genetics, VA Greater Los Angeles Healthcare System; Associate Clinical Professor, Department of Medicine, David Geffen School of Medicine at UCLA, Affiliate Natural Scientist, RAND Corporation; J. Sanford Schwartz, M.D., F.A.C.P., Leon Hess Professor of Medicine and Health Management & Economics, School of Medicine and The Wharton School, University of Pennsylvania. CONFIDENTIAL: This document contains proprietary information that is intended solely for Blue Cross and Blue Shield Plans and other subscribers to the TEC Program. The contents of this document are not to be provided in any manner to any other parties without the express written consent of the Blue Cross and Blue Shield Association. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.5 Technology Evaluation Center Assessment Objective Tamoxifen is a nonsteroidal anti-estrogen drug classified as a selective estrogen receptor modulator. Current indications for tamoxifen, approved by the U.S. Food and Drug Administration (FDA), are: n Treatment of metastatic (Stage IV) breast cancer n Adjuvant breast cancer therapy to prevent breast cancer recurrence n Reduction of the risk of invasive breast cancer in women with ductal carcinoma in situ (DCIS) n Reduction in the incidence of breast cancer in women at high risk for breast cancer The cytochrome P450 2D6 (CYP2D6) metabolic enzyme has a major role in tamoxifen metabolism. The CYP2D6 gene is polymorphic; variant DNA gene sequences resulting in proteins with reduced or absent enzyme function may be associated with lower plasma levels of active tamoxifen metabolites, which could have an impact on tamoxifen treatment efficacy. This Assessment evaluates the evidence for CYP2D6 genotyping, compared with no testing, to direct treatment choices for patients at high risk for or with breast cancer and to improve survival outcomes. Background Tamoxifen Metabolism Tamoxifen undergoes extensive primary and secondary metabolism. Tamoxifen metabolites, rather than tamoxifen itself, are likely the primary effectors of tamoxifen benefit. Unlike a classic prodrug, however, tamoxifen retains some weak receptor binding activity (Table 1). N-desmethyl tamoxifen is the most abundant tamoxifen metabolite, but has receptor binding activity no greater than the parent drug. The metabolite, 4-hydroxytamoxifen (4-OH tamoxifen), has demonstrated 100-fold greater affinity for the estrogen receptor and 30- to 100-fold greater potency in suppressing estrogen-dependent in vitro cell proliferation when compared with the parent drug (summarized in Goetz et al. 2008). However, 4-OH tamoxifen represents less than 20% of the product of tamoxifen primary metabolism (Fabian et al. 1981). The secondary metabolite, 4-hydroxy-N-desmethyl tamoxifen (endoxifen), has identical properties and potency compared 6 with 4-OH tamoxifen in terms of its binding affinity to estrogen receptors, suppression of in vitro estrogen-receptor-dependent cell proliferation, and gene expression of progesterone receptors, a marker of estrogenic effect (Stearns et al. 2003; Johnson et al. 2004; Lim et al. 2005; Lim et al. 2006). Steady-state plasma endoxifen concentrations are, on average, 5- to 10-fold higher than 4-OH tamoxifen (Stearns et al. 2003), although variability among individuals may be high (2- to 23-fold; Jin et al. 2005). It has been assumed that endoxifen is the major active metabolite of tamoxifen. Endoxifen is formed predominantly by the CYP2D6-mediated oxidation of N-desmethyl tamoxifen. The CYP2D6 enzyme has known interindividual variability in activity and therefore has been of great interest in investigating tamoxifen metabolism and variation in circulating active metabolite levels. Metabolic Enzyme Genotypes The CYP2D6 gene exhibits a high degree of polymorphism, with more than 100 allelic variants identified (The Human Cytochrome P450 [CYP] Allele Nomenclature Database; available at http://www.cypalleles.ki.se). Although the most prevalent CYP2D6 *1 and *2 alleles (both termed “wild-type” for this Assessment) produce an enzyme with normal activity, there are several variant (V) alleles that result in enzymes with no activity or reduced activity (see Table 2). Because individuals have 2 CYP2D6 alleles, various combinations of the possible alleles result in a spectrum of CYP2D6 function; these have been categorized as extensive metabolizers (EM or “normal”), intermediate metabolizers (IM), and poor metabolizers (PM), based originally on pharmacokinetic studies of CYP2D6-dependent probe drugs before the discovery of the genetic basis of variable function. An additional, rare category of ultra-rapid metabolizers (UM) is defined by the possession of 3 or more functional alleles due to gene duplication. UMs have greater functional activity than EM genotypes because of additional expression of enzyme from the extra gene(s). Griese et al (1998) studied the correlation of CYP2D6 functional categories, determined by metabolic capacity using a probe drug (sparteine), with genotypes in 195 white individuals in Germany. Although all PMs were “unambiguously identified as carriers of two nonfunctional alleles ... the most frequent functional ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment Table 1. Comparison of Tamoxifen and 3 Metabolites: Metabolism, Serum Concentration, and Estrogen Receptor Binding Affinity (Dowsett and Haynes 2003; Lee et al. 2003; Jin et al. 2005; Goetz et al. 2008) Metabolite Predominant CYP Isoform for Formation Mean Serum Concentration at Steady State, mean (SD), ng/mLa Mean Estrogen Receptor Affinity, mean (SD)b TAM NA 116 (28) 3 (2) N-desmethyl TAM CYP3A4/5 215 (62) 2 (1) 4-OH TAM CYP2D6 3 (1) 181 (84) CYP2D6 5 (3)c 181d Primary metabolites Secondary metabolite 4-hydroxy-N-desmethyl TAM (endoxifen) TAM: tamoxifen; NA: not available a In women receiving tamoxifen 20 mg daily. b Reported in multiples of estradiol receptor binding affinity in animal studies. c Derived from 17 women, genotype status, and concurrent use of CYP2D6 inhibitors unknown (Lee et al. 2003). d Reported in Lash et al. 2009 without citation. Johnson et al. (2004) reported that the relative affinity of 4-OH-tamoxifen and endoxifen was approximately 35% and 25% that of estradiol, respectively, in in vitro radioligand competitive receptor binding assays. In fluorescence receptor binding assays (i.e., comparison of 4-OH-tamoxifen and endoxifen to displace a fluorescent estrogen from recombinant estrogen receptors), both compounds had apparently identical estrogen receptor affinity. Table 2. Frequencies of the Most Prevalent CYP2D6 Alleles Across Ethnic Groups Allele Type CYP2D6 Allele Caucasian (%) African-American (%) Asian (%) Functional *1 33–40 28–50 23–42 *2 22–34 11–78 9–20 *9 0–2.9 0 3.3 *10 1.9–8 3.1–8.6 38–70 *17 0.1–0.3 9–34 0.5 *41 8 – – *3 1–3.9 0–0.5 0.8–1 *4 12–23 1.2–7 0–2.8 *5 1.6–7.3 0.6–6.1 4.5–6.1 *6 0.7–1 0 – *8 (rare) (rare) (rare) *1 × 2 0.2–0.5 3.3 0.5 *2 × 2 0.7–1.6 1.6–2.5 0–1 *4 × 2 0.1–0.2 0.9 – Reduced function Nonfunctional Duplication Reproduced from Beverage et al. CYP2D6 polymorphisms and the impact on tamoxifen therapy. J Pharm Sci, 2007; 96(9):2224-31; Copyright © 2007 American Pharmacists Association; Reprinted with permission of Wiley-Liss, Inc., a subsidiary of John Wiley & Sons, Inc. Modified with information on *8 from Sachse et al. (1997); Kubota et al. (2000); Ji et al. (2002); Griese et al. (1999). ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.7 Technology Evaluation Center genotypes extensively overlapped.” The authors concluded that, except for PMs, genotype was not a useful predictor of function. Thus, fully functional (homozygous wild-type) genotypes are consistently assigned to the EM category and homozygous inactive variant genotypes are consistently assigned to the PM category in pharmacogenomic studies. However, assignment of other genotypes with function in between these 2 is inconsistent among authors and requires standardization so that results may be better compared across studies (Beverage et al. 2007). The prevalence of CYP2D6 PMs, defined either by metabolic function or by the detection of 2 nonfunctional alleles, has been estimated in various ethnic populations in several studies, summarized by Bernard et al. (2006). The PM prevalence is approximately 7% to 10% in whites of Northern European descent, 1.9% to 7.3% in African Americans, and 1% or less in most Asian populations studied. The PM phenotype in whites is largely accounted for by CYP2D6*3 and *4 nonfunctional variants (see Table 2). In African American and Asian populations, the nonfunctional *5 variant allele is present in at most 6% to 7%, but homozygous genotypes are relatively rare. However, some PMs may reflect the combination of a nonfunctional and a reduced function allele. Among reduced function variants, *17, *10, and *41 are the most important in African Americans, Asians, and whites, respectively. Few studies have investigated the frequency of CYP2D6 variant alleles or of PMs in the Hispanic population (Bernard et al. 2006). The impact of CYP2D6 genotype and phenotype is the most extensively studied pharmacogenomic influence on tamoxifen treatment, and for that reason is the sole topic of this Assessment. Other enzymes involved in tamoxifen metabolism include CYP2B6, CYP2C9, CYP2C19, and CYP3A. Enzymes involved in metabolite elimination include sulfotransferase 1A1 (SULT1A1) and uridine diphosphate glucuronosyltransferase 2B15 (UGT2B15). Endocrine therapy efficacy is also affected by other proteins, such as those that regulate estrogen receptor activity and enzymes involved in the metabolism of aromatase inhibitors (AIs). Polymorphisms that may affect overall efficacy of tamoxifen and other endocrine treatments have been found in the genes for these proteins and enzymes. Research in these areas is in an earlier discovery stage 8 compared with the research on CYP2D6, and will not be discussed further in this Assessment. Genetic Variability and Endocrine Therapy Regimens Current National Comprehensive Cancer Network (NCCN, 2013) breast cancer treatment and risk reduction recommendations for FDAapproved uses of tamoxifen are shown in Table 3. Because a small, but significant, proportion of most ethnic populations have markedly reduced CYP2D6 metabolic capacity, there is concern that similar proportions of patients treated with tamoxifen may have poorer outcomes than patients with full CYP2D6 activity. Some have recommended that patients who are to receive tamoxifen be genotyped for CYP2D6, and that PMs be treated with alternative therapy, if possible. As shown in Table 3, tamoxifen is the only adjuvant treatment approved for preventing breast cancer in premenopausal women with DCIS (about 20% of all new breast cancers; American Cancer Society 2012) and in high-risk premenopausal women. Therefore, pharmacogenomic evaluation would not change treatment in these women. In the adjuvant setting, tamoxifen currently is the most commonly prescribed treatment for hormone receptor-positive breast cancer. For women who are premenopausal at diagnosis, pharmacogenomic evaluation could direct consideration of ovarian ablation or suppression in CYP2D6 PMs. Ovarian ablation (oophorectomy or irradiation) is an effective treatment compared with no adjuvant therapy (Adjuvant Breast Cancer Trials Collaborative Group [ABCTCG] 2007), but does not appear to add benefit to adjuvant chemotherapy (ABCTCG 2007). Acute and chronic adverse effects include hot flushes, sweats, and sleep disturbance. Functional ovarian suppression (with gonadotropin-releasing-factor analogs) in women with hormone receptor-positive tumors confers benefits comparable to chemotherapy. In postmenopausal women, who make up the majority of patients with breast cancer, raloxifene is an alternative treatment option, with efficacy equal to that of tamoxifen but markedly reduced risk of endometrial hyperplasia. Although the steroidal aromatase inactivator, exemestane, is recommended for risk reduction in high-risk postmenopausal women, it is not currently FDA-approved for this indication (see full prescribing information at http://www. aromasin.com/). ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment Table 3. NCCN-Recommended Endocrine Therapy for Women With or at Risk for Breast Cancer Indication Treatment Class SOR Surgical or radiotherapeutic 2A LHRH agonist (goserelin or leuprolide) 2A –Tamoxifen –Toremifene ER modulatorb 2A –Tamoxifen –Toremifene ER modulator 2A –Anastrozole –Letrozole –Exemestane AI 2A Fulvestrant ER down regulator 2A Megestrol acetate Progestin 2A Fluoxymesterone Androgen 2A Ethinyl estrogen High dose estrogen 2A Metastatic disease Premenopausal at diagnosis Ovarian ablationa Ovarian suppression Postmenopausal at diagnosisb Premenopausal or postmenopausalb at diagnosis a Adjuvant therapy to prevent recurrence Premenopausal at diagnosis Tamoxifen for 5 y 1 ± Ovarian ablation/suppression 2B Followed by: Postmenopausal at diagnosis – AI for 5 y if postmenopausal 1 – Tamoxifen to complete 10 y (pre- or postmenopausal) 1 – No further endocrine therapy if premenopausal 2A AI for 5 y 1 AI for 2–3 y plus tamoxifen to complete 5 y 1 Tamoxifen for 2–3 y plus AI to complete 5 y 1 Tamoxifen for 2–3 y plus AI for 5 y 2B Tamoxifen for 4.5–6 y plus AI for 5 y 1 Tamoxifen for 9.5–10 y 1 Tamoxifen for 5–10 y c 1 Risk reduction after DCIS or in high-risk women Premenopausal Tamoxifen Postmenopausal Tamoxifen 1 Raloxifene 1 Exemestane ER modulator AI 1 2A Estrogen receptor (ER)– and/or progesterone receptor (PR)–positive disease predicts likely benefit from tamoxifen. However, due to (1) the possibility of false-negative ER and PR tumor assessments, (2) heterogeneity in receptor expression between primary and metastatic sites, (3) low toxicity of endocrine therapy, and (4) potential efficacy, NCCN recommends consideration of endocrine therapy in patients with hormone receptor-negative disease localized to bone or soft tissue or with asymptomatic visceral disease only. (NCCN, 2013). Guidelines available at www.nccn.org. AI, aromatase inhibitor; ER, estrogen receptor modulator; LHRH, luteinizing hormone releasing hormone; SOR, strength of recommendation a Ovarian ablation/suppression is followed by endocrine therapy as for postmenopausal women. b If no prior endocrine therapy within 1 year. c For women with a contraindication to AI or who decline or are intolerant of AI therapy. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.9 Technology Evaluation Center In clinical practice, AIs may eventually replace tamoxifen for adjuvant therapy in postmenopausal women with hormone receptor-positive tumors because of fewer adverse effects and equal or better efficacy. In the multicenter, double-blind Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial, adjuvant treatment with anastrozole at 1 mg daily was compared with tamoxifen at 20 mg daily. Recurrence-free survival (RFS) at approximately 8 years was improved in the anastrozole arm compared with the tamoxifen arm: hazard ratio (HR)=0.85, 95% confidence interval (CI), 0.76 to 0.94, p=0.003 (ATAC Trialists’ Group 2008); there was no significant effect on overall survival. Table 4 shows results for prespecified adverse events in the ATAC trial at a median follow-up of 5 years; in particular, patients receiving anastrozole had a statistically significant decrease in hot flashes, vaginal bleeding, vaginal discharge, endometrial cancer, venous thromboembolic events (including deep venous thrombosis), and ischemic cerebrovascular events compared with patients receiving tamoxifen (shaded areas of Table 4). There were no significant differences in risk of cardiovascular morbidity or mortality; fracture rates were higher in patients treated with anastrozole versus tamoxifen during active treatment, but not after treatment completion (ATAC Trialists’ Group 2008). Results from the Breast International Group (BIG) 1-98 trial, designed to compare AI alone with sequential AI + tamoxifen and to tamoxifen alone, indicated that AI (letrozole) alone results in significantly fewer early relapses than tamoxifen (Mauriac et al. 2007). However, sequential use of tamoxifen and AI did not show improved disease-free survival (DFS) compared with AI monotherapy at a median of 71 months follow-up (Mouridsen et al. 2009). Thus, tamoxifen may not be the first choice for adjuvant treatment in postmenopausal women. However, because AIs are contraindicated in premenopausal women, and because tamoxifen remains important in the treatment of metastatic cancer where either tamoxifen or AI resistance may develop, the use of pharmacogenomics to improve the likelihood of tamoxifen benefit remains of interest. Pharmacologic Inhibitors of Metabolic Enzymes CYP2D6 activity may be affected not only by genotype, but also by coadministration of drugs Table 4. Number (%) of Patients With Prespecified Adverse Events in the ATAC Triala Adverse Events Anastrozole (n=3,092), n (%) Tamoxifen (n=3,094), n (%) Odds Ratio 95% CI All fractures 315 (10) 209 (7) 1.57 1.30 to 1.88 Fractures of spine, hip, wrist 133 (4) 91 (3) 1.48 1.13 to 1.95 Musculoskeletal eventsb 1100 (36) 911 (29) 1.32 1.19 to 1.47 Ischemic cardiovascular disease 127 (4) 104 (3) 1.23 0.95 to 1.60 Mood disturbances 597 (19) 554 (18) 1.10 0.97 to 1.25 Fatigue/asthenia 575 (19) 544 (18) 1.07 0.94 to 1.22 Nausea and vomiting 393 (13) 384 (12) 1.03 0.88 to 1.19 Cataracts 182 (6) 213 (7) 0.85 0.69 to 1.04 Hot flashes 1104 (36) 1264 (41) 0.80 0.73 to 0.89 Ischemic cerebrovascular events 62 (2) 88 (3) 0.70 0.50 to 0.97 Deep venous thromboembolic events 48 (2) 74 (2) 0.64 0.45 to 0.93 Venous thromboembolic events 87 (3) 140 (5) 0.61 0.47 to 0.80 Vaginal bleeding 167 (5) 317 (10) 0.50 0.41 to 0.61 Vaginal discharge 109 (4) 408 (13) 0.24 0.19 to 0.30 Endometrial cancer 4 (0.2) 13 (0.6) 0.31 0.10 to 0.94 a b Reproduced from anastrozole (Arimidex®) prescribing information (available at http://www.arimidex.com/). Refers to joint symptoms, including joint disorder, arthritis, arthrosis, and arthralgia. 10 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment that inhibit the metabolic activity of CYP2D6. For example, in healthy volunteers found to be EM phenotype, CYP2D6 activity was determined by measuring the metabolic products of CYP2D6-dependent probe drugs before and after administration of potential CYP2D6 inhibitory medications. Studies of selective serotonin reuptake inhibitors (SSRIs) in particular have shown that fluoxetine and paroxetine, but not sertraline, fluvoxamine, or venlafaxine, are potent CYP2D6 inhibitors (Alfaro et al. 1999; Alfaro et al. 2000; Lam et al. 2002). Some individuals treated with fluoxetine or paroxetine changed from EM phenotype to PM (Alfaro et al. 1999). The degree of inhibition may depend on the SSRI dose; for example, sertraline may be weakly if at all inhibitory at 50 mg but can become a potent inhibitor at higher doses (Sproule et al. 1997). SSRIs are often prescribed to alleviate hot flashes, which can be an adverse effect of tamoxifen therapy. However, research has suggested that hot flashes accompanying tamoxifen treatment predict a lower likelihood of breast cancer recurrence (Mortimer et al. 2007). Reduction in hot flashes with SSRI coadministration may reflect CY2D6 inhibition, reduction of tamoxifen metabolism, and reduced levels of active tamoxifen metabolites, resulting in poorer outcomes. Contrasting with this hypothesis are results from a study indicating that venlafaxine, at doses previously shown not to inhibit CYP2D6 activity, can also reduce hot flashes during tamoxifen treatment (Loprinzi et al. 2000). Currently, both NCCN breast cancer guidelines (2013) and an American Society of Clinical Oncology (ASCO) clinical practice guideline update on adjuvant endocrine therapy for women with hormone receptor–positive breast cancer (Burstein et al. 2010) recommend caution regarding coadministration of certain serotonin reuptake inhibitors that are strong inhibitors of CYP2D6 (fluoxetine and paroxetine). Because CYP2D6 inhibitors may have the potential to change the CYP2D6 phenotype, it has been recommended that studies of CYP2D6 genotype and tamoxifen treatment outcomes account for the use of CYP2D6 inhibitors in assigning CYP2D6 functional status.* Guidelines Regarding the use of CYP2D6 genetic testing before prescribing tamoxifen, NCCN breast cancer guidelines (NCCN 2013) state, “At this time, based on current data the panel does not endorse routine CYP2D6 testing for women being considered for tamoxifen therapy.” The ASCO 2009 guidelines update (Burstein et al. 2010) states, “The Update Committee recommends against using CYP2D6 genotype to select adjuvant endocrine therapy.” Regulatory Status The Roche AmpliChip CYP450 Test is cleared by FDA and is “intended to identify a patient’s CYP2D6 and CYP2C19 genotype from genomic DNA extracted from a whole blood specimen. Information about CYP2D6 and CYP2C19 genotype may be used as an aid to clinicians in determining therapeutic strategy and treatment dose for therapeutics that are metabolized by the CYP2D6 or CYP2C19 gene product” (http://molecular.roche.com/assays/Pages/ AmpliChipCYP450Test.aspx). CYP2D6 genotyping assays are also available as laboratory developed tests (LDTs). Clinical laboratories may develop and validate tests in-house and market them as laboratory services; laboratories offering an LDT as a clinical service must meet the general regulatory standards of the Clinical Laboratory Improvement Act (CLIA) and must be licensed by CLIA for high-complexity testing. Although FDA has technical authority to regulate LDTs, to date there has been no active oversight. FDA has been considering updating the label for tamoxifen (brand and generics) with information or recommendations regarding CYP2D6 genotyping and impact on tamoxifen efficacy. On October 18, 2006, FDA held an Advisory Committee meeting to answer specific questions regarding the evidence and recommendations for the label update; the questions and a summary of the Advisory Committee responses are presented in Table 5. Since the Advisory Committee meeting, AstraZeneca, the brand name (Nolvadex®) manufacturer, has ceased producing tamoxifen and is no longer maintaining the prescribing information. As of the * CYP2D6 is not considered to be an inducible enzyme in vivo (Ingelman-Sundberg 2005; Lynch and Price 2007). ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.11 Technology Evaluation Center Table 5. Questions Submitted to the FDA Advisory Committee for Pharmaceutical Science, Clinical Pharmacology Subcommittee (October 18, 2006) and Summaries of Subcommittee Answers from the Final Minutes of the Advisory Committee Meeting Questions Answers 1.The scientific evidence on the metabolism of tamoxifen demonstrates that CYP2D6 is an important pathway in the formation of endoxifen. No disagreement. 2.The pharmacologic and clinical evidence are sufficient to demonstrate that endoxifen significantly contributes to the pharmacologic Although the Subcommittee felt that CYP2D6 contributed clinically to the level of endoxifen in in vitro data, there was no direct concentration/response information to indicate that endoxifen is a major contributor to the clinical effect of tamoxifen. (anti-estrogenic) effect of tamoxifen. 3.Does the clinical evidence demonstrate that postmenopausal women with ER-positive breast cancer who are CYP2D6 poor metabolizers (by genotype or drug interaction) are at increased risk for breast cancer recurrence? If yes, should the tamoxifen label include information about increased risk for breast cancer recurrence in CYP2D6 poor metabolizers prescribed tamoxifen? The label should be updated to reflect the increased risk for breast cancer along with the mechanistic data presented. 4.Is there sufficient scientific and clinical evidence to support revisions of the tamoxifen label that recommends CYP2D6 genotype testing for postmenopausal patients before they are prescribed tamoxifen for adjuvant treatment? The Subcommittee did not reach consensus on this question. Some members felt that the genetic test should be RECOMMENDED while others felt that it should be mentioned in the label as an OPTION for discussion between the health care provider and patient. However, the majority indicated that it should be included in an appropriate section of the package insert. Available at http://www.fda.gov/ohrms/dockets/ac/cder06.html. ER, estrogen receptor date of this Assessment, FDA has delivered no direction on revised labeling of generic versions of tamoxifen to include CYP2D6 genotyping information. Methods In June 2009, after publication of a study indicating that certain SSRIs in combination with tamoxifen increased breast cancer recurrence rates (Aubert et al. 2009), FDA indicated that changes to the label regarding the interaction of tamoxifen and certain SSRIs were likely. However, these changes have yet to appear in product labels. Search Methods MEDLINE® was searched (via PubMed) using the search string (“Breast Neoplasms”[MeSH®] AND “Tamoxifen”[MeSH®]) AND “Cytochrome P-450 Enzyme System”[MeSH®] through November 2013. Clinical trials, recent reviews (2008-2013), editorials, and letters related to the pharmacogenomics of tamoxifen were retrieved. Additionally, we searched text and reference lists of retrieved papers for other relevant articles. Clinical Trials of CYP2D6 Pharmacogenomics and Tamoxifen in Progress The ClinicalTrials.gov database was searched for ongoing studies related to tamoxifen and CYP2D6 genotyping; Table 6 lists those that specified evaluation of the association of genotype and patient outcomes as an intended result of the trial. Study Selection We selected full-length, peer-reviewed articles reporting studies of postmenopausal women undergoing endocrine therapy whose treatment regimen selection is based on CYP2D6 genotyping versus usual selection methods; or studies of the association of CYP2D6 genotype with intermediate (tamoxifen-active metabolite 12 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment Table 6. Studies Listed in ClinicalTrials.gov That Will Report the Association of CYP2D6 Genotypes With Patient Outcomes Trial No. Country Target n Status Comment NCT00973037 Korea 922 Recruiting Using samples from prospective randomized multicenter study NCT00815555 Israel 500 Unknown* Prospective NCT01169792 Korea NR Completed No publication NCT00532454 Korea 21 Terminated Metastatic breast cancer NCT01124695 United States 240 Recruiting Patients with metastatic breast cancer treated with single agent tamoxifen NCT01220076 France 265 Unknown* Nonmetastatic, hormone receptor-positive breast cancer NCT01181518 Korea 1,000 Recruiting Prospective, observational NCT00963209 Switzerland 140 Recruiting Genotype correlation with tamoxifen metabolites and tumor recurrence NCT01357772 Italy 1,400 Recruiting Low-dose tamoxifen in women with lobular and ductal intraepithelial neoplasia NR: not reported * Information has not been verified in more than 2 years. levels) or final outcomes (time to recurrence, survival) for review. Study quality was evaluated by considering consistency of patient populations; thoroughness of CYP2D6 allele genotyping; whether CYP2D6 inhibitors were taken into account when assigning patients to metabolizer status categories; possible sources of bias (e.g., survival bias, genotyping whole blood from surviving participants of retrospective studies); misclassification of metabolizer phenotype; and adjustment for variables not considered confounders of the genotype-outcome association. Medical Advisory Panel Review The Assessment was reviewed by the Blue Cross and Blue Shield Association Medical Advisory Panel (MAP) on October 2, 2013. This Assessment was initially reviewed by the Panel on February 17, 2011. To maintain the timeliness of the scientific information in this Assessment, literature searches were performed subsequent to the Panel’s review (see Search Methods section). If the search updates identified additional studies that met the criteria for detailed review, the results of these studies were included in the tables and text where appropriate. Problem Formulation Patient Indications Indications for CYP2D6 pharmacogenomic testing include patients who are to be treated with tamoxifen for prevention of breast cancer in high-risk women or women with DCIS, for adjuvant treatment to prevent breast cancer recurrence, or for treatment of metastatic disease, and for women who have no contraindications to treatment with AIs (for treatment of existing disease) or raloxifene (for prevention of disease). Postmenopausal patients, determined to be CYP2D6 PMs, could avoid tamoxifen therapy and be treated with AIs alone. Premenopausal patients with breast cancer, who are determined to be CYP2D6 PMs, could consider ovarian ablation or suppression in place of or in addition to tamoxifen treatment. All indications of tamoxifen use will be considered in this Assessment, because the biologic effects of tamoxifen treatment should not differ by treatment indication (Dieudonne et al. 2013). For any indication, coadministration of drugs that inhibit CYP2D6 activity should be taken into account. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.13 Technology Evaluation Center Technologies to Be Compared CYP2D6 testing and consequent alteration of treatment regimen in CYP2D6 PMs is compared with no testing (and no alteration of decision to treat with tamoxifen). Tamoxifen pharmacogenomics have been most often studied in the adjuvant setting in postmenopausal women with hormone receptor-positive tumors. Health Outcomes n Breast cancer –Occurrence – Time to recurrence – Disease-free survival n Overall survival Main health outcomes are disease prevention, improved time to recurrence, recurrencefree survival, and/or overall survival for patients whose treatment decisions are altered by CYP2D6 testing. As discussed further below, intermediate outcomes, such as tamoxifen-active metabolite levels (endoxifen, 4-hydroxytamoxifen) do not provide sufficient evidence unless linked to evidence of main health outcomes. Specific Assessment Questions 1. Are CYP2D6 genotyping assays accurate and reliable (i.e., analytic validity)? 2. In women who need endocrine therapy, are CYP2D6 variant genotypes significantly associated with (i.e., do they predict) intermediate and/or main health outcomes (i.e., clinical validity)? 3. In women who need endocrine therapy, does use of CYP2D6 genotype testing result in selecting endocrine therapy regimens that improve health outcomes compared with selection of endocrine therapy regimens without testing (i.e., clinical utility)? The analytic framework for questions 2 and 3 is shown in Figure 1. Review of Evidence 1. Are CYP2D6 genotyping assays accurate and reliable (i.e., analytic validity)? The Roche AmpliChip CYP450 Test for detecting CYP2D6 variants in whole blood samples has been fully validated for analytic validity; a summary of results submitted for FDA 14 clearance is provided in FDA’s decision summary (available at http://www.accessdata. fda.gov/cdrh_docs/reviews/K042259.pdf). Compared with sequencing (criterion standard), the specificity of the AmpliChip CYP450 Test for detection of wild-type samples (n=100; 3 different wild-type alleles) was 100%; sensitivity for 22 different variant alleles in 492 alleles tested was 99.2%, with no mis-calls and 4 no-calls. Reproducibility (99.9%) and other measures of assay robustness indicate highly reliable performance. The AmpliChip kit contains positive and negative quality control samples that must yield specified results for an assay run to be valid. Although comparable information on the analytic validity of LDTs is usually not available, in an experienced laboratory and with validation of in-house results compared with either sequencing or to AmpliChip, accurate and reliable performance should be achievable. For example, Heller et al. (2006) compared their in-house method with AmpliChip and achieved 95.6% agreement; 7 discordant samples contained CYP2D6 gene amplifications not detected by the in-house method (discordant results were verified by sequencing). 2. In tamoxifen-eligible women who need endocrine therapy, are CYP2D6 variant genotypes significantly associated with (i.e., do they predict) intermediate and/ or main health outcomes (i.e., clinical validity)? The analytic framework for assessing the clinical validity of CYP2D6 genotyping is shown in Figure 1. There is direct evidence and a chain of evidence. Direct evidence compares outcomes in women treated with tamoxifen or other endocrine therapy stratified by metabolizer status. The chain of evidence associates an intermediate outcome, tamoxifen metabolite plasma levels, with both CYP2D6 genotype and main health outcomes in women treated with tamoxifen. Chain of Evidence Association of Genotype with TamoxifenActive Metabolite Concentrations Six studies evaluated the association of CYP2D6 genotypes with circulating 4-OH tamoxifen and/or endoxifen levels (Table 7). All were prospective cohort studies of adjuvant treatment; tamoxifen was administered at the standard dose of 20 mg daily (or dose was not reported). ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Clinical Utility (Question 3) No Evidence Identified CYP2D6 Genotyping Genotype Directed Treatment Outcomes TamoxifenEligible Women Genotype Breast cancer: – Occurrence – Time to recurrence – Disease-free survival Overall survival Tamoxifen Treatment Metabolite (Endoxifen) Levels Clinical Validity (Question 2) – Table 7 – Table 8 Clinical Validity (Question 2) Observational Data: – Table 9 (Asian Populations) – Table 10 For question 2 (dashed lines), evidence links CYP2D6 genotype with main health outcomes in women treated with tamoxifen. A chain of evidence links CYP2D6 genotype with main health outcomes through the intermediate outcome of tamoxifen metabolite plasma levels. For question 3 (solid lines), no evidence was identified. CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.15 Figure 1. Analytic Framework for Assessment Questions 2 and 3 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. – TAM Use –Dose Study n Study Design, Patients Stearns et al. (2003) 12 Prospective cohort Breast cancer patients taking TAM and taking paroxetine (SSRI) for hot flashes Jin et al. (2005) 80 Prospective cohort Newly diagnosed, postsurgery breast cancer patients starting TAM –Duration Before Evaluation –Adjuvant – 20 mg/d – >4 wk –Adjuvant –(Dose not reported) – 4 mo Study Accounted for CYP2D6 Inhibitors? Yes Gene (Typed Variants) Comparison Results CYP2D6 (*4, *6, *8) wt/V or V/V vs. wt/wt Baseline endoxifen concentrations were lower in V carriers (p=0.002) (Patients taking other CYP2D6 inhibitors excluded) No CYP2D6 genotype wt/wt (n=7) wt/V or V/V (n=5) CYP2D6 (*1,*3, *4, *5,*6) wt/wt vs. wt/V vs. V/V Pre- vs. Post-SSRI Endoxifen Decrease % 64 24 p Value 0.03 Mean concentration after 4 mo: Genotype (n) Endoxifen 95% CI 4-OH TAM 95% CI wt/wt (48) 78.0 nM 65.9–90.1 9.5 8.4–10.6 wt/V (29) 43.1 33.3–52.9 8.3 6.7–9.9 V/V (3)20.011.1–28.9 7.11.2–13.0 p-value <0.001 0.86 Distribution of individual patient results shows overlap among all groups. Yes No CYP2D6 inhibitor vs. CYP2D6 inhibitor by genotype Genotype ± Inhibitor (n) wt/wt – inhib. (34) wt/wt + inhib. (13) wt/V – inhib. (17) wt/V + inhib. (11) V/V – inhib. (3) V/V + inhib (0) Mean Endoxifen Percent Level (nM) Decrease 91.4 38.6 57.8 51.7 31.0 40.0 20.0 – p Value 0.003 0.08 – Technology Evaluation Center 16 Table 7. Studies Reporting Association of CYP2D6 Genotype With Tamoxifen-Active Metabolite Levels Study n Study Design, Patients Borges et al. (2006) 158 Prospective cohort Newly diagnosed, postsurgery breast cancer patients starting TAM – TAM Use –Dose –Duration Before Evaluation Study Accounted for CYP2D6 Inhibitors? –Adjuvant No – 20 mg/d – 4 mo Gene (Typed Variants) CYP2D6 (33 alleles by AmpliChip a also *3, *4, *6, *7, *8, *10, *17 by alternate methods) Comparison Results EM vs. IM vs. PM Phenotype,c n EM (68) IM (71) PM (19) p Value <0.001 Each functional category comprised a variety of possible genotypes, listed in Borges et al. 2006. Although mean ratios differed significantly, individual patient data points for all groups overlapped. c d Yes Plasma Ratio, mean (SD)d 0.18 (0.09) 0.09 (0.04) 0.04 (0.02) EM ± CYP2D6 inhibitor Phenotype determined by genotype classification. Plasma ratio = endoxifen to N-desmethyl tamoxifen ratio. Plasma Percent p Value PhenotypeEndoxifena Decrease EM or 84.1 (39.4) EM + weak inhibitor vs. 93.6 (38.6) EM + potent inhibitor 23.5 (9.5) 72.1 <0.001 PM (no inhibitors) 19.4 (6.10 a Values are mean (SD), nM. (Similar trends found in other major phenotypes.) CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.17 Table 7. Studies Reporting Association of CYP2D6 Genotype With Tamoxifen-Active Metabolite Levels (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Study n Study Design, Patients Lim (2007) 202 Prospective cohort, Korean women with early or metastatic breast cancer taking TAM – TAM Use –Dose –Duration Before Evaluation –Adjuvant or treatment of metastatic disease, – 0 mg/d, – > 8 wk Study Accounted for CYP2D6 Inhibitors? Yes (patients using CYP2D6 inhibitors excluded) Gene (Typed Variants) Comparison Results CYP2D6 (*2xN, *5, *10) *10/*10 vs. wt/wt or wt/*10 Genotype (n) wt/wt (64) or wt/*10 (89) vs. *10/*10 (49) 37 Kiyotani et al. (2010) 98 Pre- and postmenopausal women with newly diagnosed breast cancer starting TAM –Adjuvant – 20 mg/d – >4 wk Independently recruited patients with breast cancer taking TAM –Adjuvant – 20 mg/d – >4 wk Yes No patients were taking CYP2D6 inhibitors Yes (patients taking SSRIs not included) 4-OH TAMa 2.8 2.5 1.5 (p<0.001) Results were similar if *10 and *5 were combined as variant alleles; *5 allele frequency was 5%. a Xu et al. (2008) Endoxifena 19.9 18.1 7.9 (p<0.001) Values are ng/mL. CYP2D6 (*10) *10/*10 or wt/*10 vs. wt/wt 4-HydroxyPercent Genotype n Tamoxifen Decrease p Value 185.3 wt/wt 7 5.2 2.0 0.96 wt/*10 *10/*10 124.1 22.6 0.04 CYP2D6 (*1; variant alleles V: *4, *6, *10, *14B, *18, *21, *36, *41) V/V or wt/V vs. wt/wt Genotype PlasmaPercent Endoxifena Decrease p Value wt/wt35.4 27.223.2 wt/V 15.556.2 <.001 V/V 4-HydroxyPercent Tamoxifena Decrease p Value Genotype wt/wt5.3 wt/V 4.221 3.142 <.001 V/V a Values are ng/mL. TAM, tamoxifen; 4-OH TAM, 4-hydroxytamoxifen; chemo, chemotherapy; V, variant; wt, wild type (*1 or *2); EM, extensive metabolizer; IM, intermediate metabolizer; PM, poor metabolizer; SSRI, selective serotonin reuptake inhibitor a AmpliChip detects CYP2D6 alleles *1 to *10AB, *11, *14A, *14b, *15, *17, *19, *20, *25, *26, *29 to *31, *35, *36, *40, *41, *1xN, *2xN *4xN, *10xN, *17xN, *35xN, and *41xN. Technology Evaluation Center 18 Table 7. Studies Reporting Association of CYP2D6 Genotype With Tamoxifen-Active Metabolite Levels (cont’d) CYP2D6 Pharmacogenomics of Tamoxifen Treatment Metabolite levels were determined at a minimum of 4 weeks from the start of tamoxifen treatment. In 5 studies, the presence of nonfunctional variant alleles (Stearns et al. 2003; Jin et al. 2005; Borges et al. 2006) or the presence of homozygous reduced function variant alleles (Lim et al. 2007; Kiyotani et al. 2010) was associated with significantly reduced endoxifen levels. Although mean endoxifen levels for each genotype group differed significantly, individual patient data points for all groups overlapped considerably in 2 studies that reported these data (Jin et al. 2005; Borges et al. 2006). Four studies also reported 4-OH tamoxifen levels by CYP2D6 genotype, finding nonsignificant differences in one (Jin et al. 2005) and significant differences in 3 (Lim et al. 2007; Xu et al. 2008; Kiyotani et al. 2010). Because the production of 4-OH tamoxifen can be effected by several different CYP450 enzymes, it is unclear whether major differences by CYP2D6 genotype are expected. When examined, coadministration of a potent CYP2D6 inhibitor medication (the SSRIs paroxetine or fluoxetine) to homozygous wild-type (EM) patients resulted in endoxifen levels close to those of homozygous nonfunctional genotype (PM) patients (Jin et al. 2005; Borges et al. 2006). Coadministration of a weak CYP2D6 inhibitor (various, e.g., the SSRIs sertraline or citalopram; celecoxib) was not associated with decreased endoxifen in 1 study (Borges et al. 2006). Thus, it is important to consider the use of potent CYP2D6 inhibitors when assigning metabolizer status to patients in studies of the association of CYP2D6 genotype with clinical outcome.* When inhibitor medication is not taken into account in comparing endoxifen levels by genotype, the results represent the weakest case, because some genotypic EMs may be functional PMs. Summary. Five prospective cohort studies of adjuvant tamoxifen treatment provide consistent evidence that CYP2D6 nonfunctional variant alleles are associated with significantly reduced plasma endoxifen levels. However, endoxifen levels overlap across all genotypes, suggesting that CYP2D6 genetic variability does not explain all variability in endoxifen levels. Somewhat surprisingly, because generation of 4-OH tamoxifen does not depend predominantly on CYP2D6 as does generation of endoxifen, 3 of 4 studies report a significant association of low CYP2D6 function with reduced plasma 4-OH tamoxifen levels. Coadministration of a potent CYP2D6 inhibitor to CYP2D6 homozygous wild-type patients (EMs) is associated with endoxifen levels near those of patients who are PMs; thus use of CYP2D6 inhibitors should be taken into account in assigning metabolizer status in studies of the association of CYP2D6 genotype with clinical outcomes. Association of Tamoxifen-Active Metabolite Levels With Clinical Outcomes Two studies (Xu et al. 2008 and Kiyotani et al. 2010; see Table 10) measured 4-OH tamoxifen and/or endoxifen levels as well as patient outcomes and correlated CYP2D6 genotypes with both effector metabolite levels and with clinical outcome. Both studies were small and were conducted in Asian populations in which the CYP2D6*10 reduced function variant is common. Xu et al. (2008) genotyped patients only for the *10 variant; Kiyotani et al. (2010) genotyped for *10 and for several other variants, but the *10 allele accounted for the vast majority of variant alleles detected. Xu et al. (2008) measured only 4-OH tamoxifen levels, lacking an endoxifen standard for measurement of that metabolite. The authors reported a significant decrease in 4-OH tamoxifen levels for patients with the *10/*10 genotype (see Table 7) and a corresponding significant reduction in 5-year DFS (HR for distant metastasis or death from breast cancer = 4.7; 95% CI, 1.1 to 20) relative to wild-type homo- or heterozygotes, but not in disease-specific survival, defined as time from diagnosis to death from breast cancer (Table 8). Kiyotani et al. reported a significant trend for decreased endoxifen and 4-OH tamoxifen across wild type/variant and variant/variant genotypes compared with wild type/wild type, and reported significant and increasing HRs for RFS for variant genotypes (wild type/variant: HR for breast cancer recurrence [locoregional, contralateral, or distant metastasis] = 4.4; 95% CI, 1.3 to 15.0; variant/ variant: HR = 9.5; 95% CI, 2.8 to 32.5) compared with homozygous wild type. * It may also be important to avoid use of potent CYP2D6 inhibitors when prescribing tamoxifen; however, this Assessment does not address that question. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.19 Table 8. Studies Reporting Both Association of CYP2D6 Genotype With Tamoxifen Active Metabolites and With Clinical Outcomes ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. n Xu et al (2008) 152 [Asian population] Kiyotani et al. (2010a), update of Kiyotani et al. (2008) [Asian population] 282 Pre- and postmenopausal women with newly diagnosed breast cancer receiving surgery and starting tamoxifen monotherapy Dec 1994 to Nov 2005 –Adjuvant – 20 mg/d Cross-sectional selection of pre- and postmenopausal surgical patients with ER+ invasive breast cancer receiving TAM 1986-2007, seen again Sep 2007 to Apr 2009 –Adjuvant – 20 mg/d – 5 y –7.1 y (range: 0.8–23.5) –NR – 5.25 y Study Accounted for CYP2D6 Inhibitors? No patients were treated with known inhibitors of CYP2D6 Gene (Typed Variants) Comparison Results CYP2D6 (*10) PM (n=28) [*10/*10] Whole blood, fresh-frozen tumor, or vs. 4-OH TAM Genotype n wt/wt18 5.3 wt/*10 7 5.2 *10/*1012 4.1 paraffinembedded negative axillary LN No patients were treated with SSRIs CYP2D6 (*1 = wt; variant alleles V: *4, *6, *10, *14B, *18, *21, *36, *41) Whole blood collected Sep 2007 to Apr 2009 % Decrease p Value 2.0 22.6 0.96 0.04 EM (n=124) [*1/*1, *1/*10] 5-Year HRa for HRa for 5-Year DSS Genotype DFS, % 5-Year DFS 89 4.7 (1.1 to 20) 2.7 (0.4 to 17.3) PM EM 96Reference Reference a Adjusted for age, clinical stage, LN, tumor size, adjuvant therapy, surgery, HER-2, and hormone receptor status. Values are HR (95% CI). V/V or wt/V p Value Genotype Plasma Endoxifena % Decrease wt/wt35.4 wt/V27.2 23.2 V/V 15.5 56.2<.001 vs. wt/wt Genotype 4-OH TAMa wt/wt5.3 wt/V4.2 V/V 3.1 % Decrease p Value 21 42<.001 Genotype HR (95% CI) for RFSb V/V 9.52 (2.79 to 32.45) wt/V 4.44 (1.31 to 15.0) wt/wt (Reference)1.0 a Values are ng/mL. b Adjusted for tumor size and LN status TAM, tamoxifen; 4-OH TAM, 4-hydroxytamoxifen; chemo, chemotherapy; V, variant; wt, wild type (*1 or *2); EM, extensive metabolizer; IM, intermediate metabolizer; PM, poor metabolizer; SSRI, selective serotonin reuptake inhibitor; HR, hazard ratio; OR, odds ratio; RFS, recurrence-free survival; DSS, disease-specific survival; LN, lymph node; ER, estrogen receptor. Technology Evaluation Center 20 Study Study Design, Patients – TAM Use – Dose and –Duration Before Evaluation CYP2D6 Pharmacogenomics of Tamoxifen Treatment A difficulty with the Kiyotani et al. (2010) study is that CYP2D6 genotypes were determined from whole blood samples collected at a time distant from breast cancer diagnosis and surgery, such that patients selected for this study had to have survived in some cases for extended periods of time before sampling. Patients who died or were lost to follow-up could not be considered; thus patient selection is likely biased toward survivors, with unpredictable effects on the genotype-clinical outcome association (Lash 2010). In the Xu et al. (2008) study, 25 of 152 included patients were genotyped from blood samples. It is unclear when blood was drawn, but if also at a time distant from surgery, similar survivorship bias may apply. Summary. Two studies report on the relationship between CYP2D6 genotype and active tamoxifen metabolites, and between genotype and clinical outcomes in the same patient population. Both studies enrolled patients from Asian populations, focusing almost exclusively on the reduced function CYP2D6*10 variant. Both studies reported reduced endoxifen and/ or 4-OH tamoxifen concentrations in patients homozygous or heterozygous for variant alleles, and in conjunction reported decreasing DFS or recurrence-free survival. One or both studies have study design flaws likely resulting in selection bias. In addition, both studies are small, resulting in estimates of association with wide CIs. Thus, the relationship between endoxifen (or 4-OH tamoxifen) plasma concentrations and clinical outcomes has not been established in Asian populations, nor has it been studied in white populations with null function CYP2D6 genotypes. Direct Evidence Association of Genotype with Clinical Outcomes We included in this Assessment 23 studies (in 24 publications) evaluating the association between CYP2D6 genotype and clinical outcomes in women treated with tamoxifen. Most of these studies examined tamoxifen use in the adjuvant setting in postmenopausal women. Study details are presented in Appendix Tables A and B. Summary tables follow. We searched for data that evaluated CYP2D6 genotype as a prognostic marker to ensure that a prognostic association would not confound the effect of genotype on tamoxifen outcomes. Four studies (Nowell et al. 2005; Schroth et al. 2007; Wegman et al. 2005; Xu et al. 2008) evaluated outcomes stratified by genotype for women not treated with tamoxifen (data not shown). Although there were limitations in study quality or reporting, none of the studies found that outcome varied by CYP2D6 genotype. Additionally, 3 studies (Toyama et al. 2009; Okishiro et al. 2009; Ramon Y Cajal et al. 2010) evaluated the association between CYP2D6 genotype and various breast cancer prognostic factors, such as tumor size, lymph node status, and histologic grade, but in all cases found no significant associations (data not shown). Due to Mendelian randomization (natural randomization of genotype), it may be expected that CYP2D6 genotypes are distributed similarly across all prognostic groups (Dezentje et al. 2009; Lash et al. 2009). Therefore, this Assessment assumed that CYP2D6 genotype, independent of tamoxifen treatment, was not a confounding factor in the evaluation of the association of CYP2D6 genotype and clinical outcomes. Several studies included non-tamoxifen-treated groups (Nowell et al. 2005; Rae et al. 2012; Regan et al. 2012; Schroth et al. 2007; Wegman et al. 2005). However, only one directly compared tamoxifen-treated with non-tamoxifentreated patients within genotype strata (Wegman et al. 2005). This group conducted a retrospective study of archived tumor samples from a randomized controlled trial of tamoxifen treatment and found that EMs (defined as non-CYP2D6*4 carriers) treated with tamoxifen received no statistically significant clinical benefit compared with EMs not treated with tamoxifen (relative risk [RR] of distant recurrence=0.9; 95% CI, 0.5 to 1.6). Paradoxically, carriers of 1 or 2 CYP2D6*4 nonfunctional variant alleles obtained significant benefit from tamoxifen treatment (RR = 0.3; 95% CI, 0.1 to 0.7). This study has several limitations: Tissue samples were available for only 226 (33%) of the originally enrolled patients; only 47 patients carried a *4 allele (of whom, only 4 were homozygous PMs) and no other variants were tested; tamoxifen dose was 40 mg daily instead of the recommended 20 mg daily and was administered for only 2 years instead of the recommended 5 years. In addition, analysis of results did not take variable chemotherapy use or CYP2D6 inhibitors into account, but did adjust inappropriately for prognostic factors ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.21 Technology Evaluation Center (i.e., tumor size, lymph node status). Because of these limitations, study results are questionable. In the included studies, we note the possibility for several types of bias in estimating the magnitude of association, defined as follows (Lash et al. 2009): n Survival (survivorship) bias: Most studies are retrospective and use archived tumor samples taken at surgery for CYP2D6 determination. Some studies, however, recall available patients at a later date and draw whole blood. These studies select only from among survivors not lost to follow up. n Overfitting: Multivariate analyses that adjust for a large number of variables in studies that included a relatively small number of patients may yield an erroneously increased estimate of association due to sparse data. n Inappropriate confounders: As discussed above, breast cancer prognostic factors are neither causally related to CYP2D6 genotype nor are they surrogates for genotype (or for the actual exposures of interest, plasma endoxifen and 4-OH tamoxifen levels). Thus, they do not satisfy criteria for confounding. Adjustment for factors not considered confounders of the association of interest (the genotype-outcome association) may introduce bias or reduce precision of effect estimates (Lash et al. 2009). When provided, univariate Cox proportional hazards or Kaplan-Meier/log-rank analyses (rather than multivariate analyses) were preferentially abstracted in data tables to avoid potential bias. n Misclassification: Classification of similar genotypes into different metabolizer status categories may erroneously reduce estimates of the strength of association. Similarly, different genotypes grouped together (e.g., IMs plus EMs) may bias results toward the null. As mentioned, in most studies, CYP2D6 germline genotype was determined from archived tumor tissue. To determine if CYP2D6 genotype sequences are changed in tumor samples compared with normal tissue samples, Toyama et al. (2009) confirmed that CYP2D6*10 genotype frequencies from peripheral whole blood and from fresh-frozen tumors were the same in 50 patients. Similarly, Lash et al. (2011) found 100% concordance for CYP2D6*4 genotyping of DNA extracted from 106 normal tissue samples compared with DNA extracted from paired tumor samples. Rae et al. (2013) analyzed white blood cell CYP2D6 genotypes (alleles *1, *2, *3, 22 *4, *6, *10, and *41) and reported concordance of 94% and 93% with DNA extracted from matched, formalin-fixed, paraffin-embedded tumor tissue and unaffected lymph nodes, respectively, in 122 breast cancer patients. Several studies enrolled patients of Asian ethnicity, in which nonfunctional CYP2D6 variants are rare, but the CYP2D6*10 variant is very common (see Background section and Table 2). CYP2D6*10 produces an unstable enzyme resulting in decreased activity. Studies of the metabolic activity of CYP2D6 in patients with the *10/*10 genotype administered an enzymespecific probe, compared with patients with the *1/*1 genotype, confirm reduced activity, but also show overlap between the 2 groups (Myrand et al. 2008). Nevertheless, it has been hypothesized that breast cancer patients with the CYP2D6*10 genotype may have worse outcomes after tamoxifen treatment compared with patients with wild-type sequences. Because of the differing CYP2D6 genotype variants by ethnicity, studies enrolling patients of Asian descent will be considered together as a group for ease of review, followed by review of all other studies. Studies of Patients of Asian Ethnicity and CYP2D6*10 Major Variant Seven retrospective cohort studies reported the association of CYP2D6 genotype or phenotype with clinical outcomes in Asian populations (see Table 9 for summary, and Appendix Table A for details). Six studied patients who were administered tamoxifen as adjuvant therapy after surgery; the other study selected patients with metastatic breast cancer (Lim et al. 2007). All studies included a mix of pre- and postmenopausal patients. Four of the 7 studies reported a significant reduction for *10 homozygotes in RFS or DFS or time to progression odds ratio compared with wild-type homozygotes (Lim et al. 2007; Kiyotani et al. 2008; Kiyotani et al. 2010a; Xu et al. 2008). CYP2D6 heterozygotes (wt/V) were usually combined with wt/wt, but in 1 study were separately significantly associated with reduced RFS (Kiyotani et al. 2010a). This last study included women taking only tamoxifen, without concomitant chemotherapy. In a companion study, Kiyotani et al. (2010b) studied a similar population of women who differed only in that their treatment also included chemotherapy; in this group, no significant association between CYP2D6 genotype and clinical ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Table 9. Clinical Validity Studies of Asian Populations and CYP2D6*10 Variant (Significant Results Highlighted, With Detail in Appendix Table A) n Lim (2007 21 1.6 x Kiyotani (2008) 67 10 x x Xu (2008) 152 5.25 x Toyama (2009) 154 7.9 Yes Study Median Follow Up, y No Misclassification Inappropriate Overfittinga Survival Bias Potential for Bias Comparator Referent Genotype n Genotype n *10/*10 12 wt/wt + wt/*10 9 *10/*10 15 wt/wt + wt/*10 43 x *10/*10 28 wt/wt + wt/*10 NR *10/*10 28 wt/wt x Other Outcome HR for RFS/DFS (95% CI) Type HR (95% CI) TTP 3.7 (1.3 to 10.7) 8.7 (1.1 to 71.1) 124 4.7 (1.1 to 20.0) DSS 2.7 (0.4 to 17.3) 64 NR OS NR (NS KM log-rank) (NS KM log-rank) wt/*10 62 wt/wt 64 NR (NS) Okishiro (2009) 173 4.7 x *10/*10 Kiyotani (2010a) (no chemo) 282 7.1 x x x V/V Kiyotani (2010b) (plus chemo) 167 NR x NR 49 wt/wt + wt/*10 133 NR 63 wt/wt 83 9.5 (2.8 to 32.4) wt/V 136 wt/wt 83 4.4 (1.3 to 15.0) V/V 63 wt/wt 83 0.64 (0.2 to 1.99) wt/V 136 wt/wt 83 1.1 (0.5 to 2.3) (NS KM log-rank) wt, wild type; V, variant; HR, hazard ratio; CI, confidence interval; RFS, recurrence-free survival; DFS, disease-free survival; DSS, disease-specific survival; OS overall survival; TTP, time to (disease) progression; NR, not reported; NS, not significant; KM, Kaplan-Meier CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.23 CYP2D6 Metabolizer Status Accounted for CYP2D6 Inhibitors? Technology Evaluation Center outcome was found. Chemotherapy does not explain results from the other 2 studies, which did not report a significant association between genotype and clinical outcome, given that 58% of the patients studied by Okishiro et al. (2009) received chemotherapy and/or goserelin, but the patients studied by Toyama et al. (2009) received tamoxifen alone. Results from 5 of the 7 studies may be affected in unpredictable ways by different types of bias, as indicated in Table 9; these included 3 of the 4 studies reporting a significant association between the CYP2D6*10 genotype and reduced DFS. Two of the studies that reported no association (Toyama et al. 2009; Okishiro et al. 2009) were designed with no obvious potential for bias. All studies were relatively small, with numbers of homozygous variants ranging from 12 to 63 (see Appendix Table A) and likely few events within each group, resulting in extremely wide CIs for all estimates (see Table 9). For example, Goetz (2010) estimated that the Okishiro et al. (2009; n=173) study had a power of 26% to detect a 2-fold increase in the hazard of disease recurrence in the *10/*10 carriers relative to wt/wt carriers. Kiyotani et al. (2010b) reported a statistical power of 63% to detect an HR of 5.4 in their earlier study (Kiyotani et al. 2010a), which reported an HR of 9.4 for RFS for patients with the lowest activity CYP2D6 allele combinations versus wild type. All Other Studies We included 13 studies (14 publications), primarily of white patients administered tamoxifen for adjuvant treatment of invasive breast cancer (12 studies) and 1 study of tamoxifentreated metastatic breast cancer patients, in this group (Table 10). Goetz et al. (2005) and Goetz et al. (2007), the latter a reanalysis of the earlier study, are counted as a single study. One of the studies of patients given adjuvant tamoxifen exclusively selected patients with BRCA1 or BRCA2 mutations (Newman et al. 2008). One study included only patients with metastatic breast cancer treated with a higher dose of tamoxifen (40 mg daily) than the dose used for adjuvant treatment (20 mg daily) (Lammers et al. 2010). Two studies assessed tamoxifen prophylaxis therapy in high-risk patients (Goetz et al. 2011; Sestak et al. 2012). Of the 16 studies, one is a matched case-control nested within a breast cancer registry (Lash et 24 al. 2011), 3 are matched case-control studies derived from completed randomized controlled trials (Goetz et al. 2011; Goetz et al. 2013; Sestak et al. 2012), 4 are other types of retrospective analyses of samples from completed clinical trials (Regan et al. 2012; Rae et al. 2012; Goetz et al. 2005/2007; Wegman et al. 2005), one evaluated relevant patients within a population-based cohort (Bijl et al. 2009), and the rest are cohort or consecutive series studies. Lash et al. (2011) genotyped archived tumor samples from a well-documented Danish breast cancer registry that uses the same 10-year follow-up protocol for all patients. The authors conducted a matched, nested case-control study in which estrogen receptor-positive patients treated with tamoxifen, who had a recurrence, were cases and those without a recurrence served as the reference population. Estrogen receptor-negative patients who were not treated with tamoxifen also were genotyped to evaluate any direct association between CYP2D6 inhibition (i.e., presence of 1 or 2 CYP2D6*4 nonfunctional alleles) and breast cancer recurrence. Several safeguards were prospectively built into the study to avoid bias, and the sample size was chosen to achieve a statistical power of 90% to detect an odds ratio of 1.5 associating reduced CYP2D6 activity with risk of breast cancer recurrence. There were no significant associations found for either homozygous or heterozygous CYP2D6*4 variant patients and breast cancer recurrence (Table 10). Point estimates and CIs for both CYP2D6 variant groups were very close to those found in estrogen receptornegative patients not treated with tamoxifen. To address potential bias introduced by genotyping only 1 variant allele, the authors conducted a probabilistic bias analysis (sensitivity analysis) using comprehensive genotyping information from another study and found little change in results. The largest studies reporting results for CYP2D6 genotype and clinical outcomes were Schroth et al. (2009; n=1345), Regan et al. (2012; n=1243), Goetz et al. (2013; n=876), Wegman et al. (2007; n=677), and Rae et al. (2012; n=588). Schroth et al. (2009) estimated that a minimum sample size of 1279 and a minimum of 166 events would be needed to detect an HR for breast cancer recurrence of 1.85 for PMs compared with EMs with a power of 90% and a 1-sided alpha level of 0.05. This group reported ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. 10b Schroth et al. (2009) 1345 Regan (2012) Rae (2012) 6.3 x x xc 973 6.3 no chemo 588 10 No 991 Misclassification Lash et al. (2011) Inappropriate Confounders n Overfittinga Study Median Follow Up, y Survival Bias Potential for Bias Yes CYP2D6 Metabolizer Status Accounted for CYP2D6 Inhibitors? x x Comparator Referent Other Outcome Genotype n Genotype n HR for RFS/DFS (95% CI) *4/*4 71 wt/wt 607 1.0 (0.8 to 1.3) wt/*4 313 wt/wt 607 1.4 (0.8 to 2.3) V/V for *3, *4, or *5 79 wt/wt *10*10, *41/*41 or *10 or *41 + *3, *4, or *5 637 V/V for *3, *4, *6 or *7 Type HR (95% CI) 629 TTR 2.1 (1.3 to 3.5) wt/wt 629 TTR 1.5 (1.1 to 2.0) 86 wt/wt 610 0.6 (0.3 to 1.2) BCFI (KM) 0.6 (0.2 to 1.2) IM (see Table B) 277 wt/wt 610 0.95 (0.5 to 1.4) BCFI (KM) 0.95 (0.50 to 1.40) IM-0.5 31 PM 38 2.8 (0.9 to 8.5) IM-1 151 PM 38 1.3 (0.5 to 3.5) IM-1.5 51 PM 38 0.8 (0.2 to 2.8) EM 317 PM 38 1.2 (0.5 to 3.2) CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.25 Table 10. Clinical Validity Studies in Primarily White Populations (Significant Results Highlighted; Detail in Appendix Table B) Table 10. Clinical Validity Studies in Primarily White Populations (Significant Results Highlighted; Detail in Appendix Table B) (cont’d) Wegman et al. (2007) 677 7.1 Goetz et al. (2005) 223 11.4 Goetz et al. (2007), reanalysis of Goetz (2005) 171 11.4 Wegman et al. (2005) 226 10.7 x x Referent Other Outcome HR for RFS/DFS (95% CI) Genotype n Genotype n x V/V for *3, *4, or *6 NR wt/wt NR OR = 2.4 (1.05 to 5.7) V/v or V/wt, V=*3, *4, or *6 and v=*10 or *41 NR wt/wt NR OR = 1.7 (1.0 to 2.9) wt/v or v/v, v=*10 or *41 NR wt/wt NR OR = 1.2 (0.6 to 2.6) xd *4/*4 35 wt/wt 475 Univariate NR (K-M *4/*4 RFS = 89% vs. wt/wt 74%, log-rank p=0.05) x *4/*4 13 wt/wt or wt/*4 177 *4/*4 16 wt/wt wt/*4 40 Tam + wt/wt Tam + wt/4* or 4*/4* x x Comparator No 5 Yes 876 Misclassification Goetz (2013) Inappropriate Confounders n Overfittinga Study Median Follow Up, y Survival Bias ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Potential for Bias x Type HR (95% CI) 2.7 (1.2 to 6.4) OS 1.7 (0.8 to 3.8) 115 2.7 (1.3 to 5.4) TTR OS 3.2 (1.4 to 7.6) 2.0 (0.9 to 4.2) wt/wt 115 1.6 (0.95 to 2.8) TTR OS 1.4 (0.7 to 3.0) 1.4 (0.8 to 2.4) 52 Tam– wt/wt 55 0.9 (0.5 to 1.6) 24 Tam– wt/4* or 4*/4* 23 0.3 (0.1 to 0.7) Technology Evaluation Center 26 CYP2D6 Metabolizer Status Accounted for CYP2D6 Inhibitors? 5.4 x Comparator Referent Other Outcome No 162 Misclassification Nowell et al. (2005) Inappropriate Confounders n Overfittinga Study Median Follow Up, y Survival Bias Potential for Bias Yes CYP2D6 Metabolizer Status Accounted for CYP2D6 Inhibitors? Genotype n Genotype n HR for RFS/DFS (95% CI) Type HR (95% CI) x *4/*4 or wt/*4 49 wt/wt 112 0.7 (0.3 to 1.4) OS 0.8 (0.3 to 1.8) *1/*4 29 *1/*1 52 DSS OS 1.9 (0.9 to 3.9) 1.5 (0.8 to 2.8) V/V, wt/*4 or wt/*5 79 wt/wt, wt/*10 or wt/*41 118 1.9 (1.1 to 3.3) TTR OS 2.2 (1.2 to 4.3) NR (NS) 2.1 (0.8 to 5.4) OS 2.5 (0.8 to 8.2) DSS OS 4.1 (1.1 to 15.9) 1.9 (0.6 to 4.6) Schroth et al. (2007) 206 5.9 x Newman et al. (2008), with BRCA patients 115 10 x x V/V for *3, *4, or *5 12 wt/wt/ or wt/*3, *4, *5, or *41 96 Bijl et al. (2009) 85 10 x x *4/*4 4 *1/*1 52 Ramon y Cajal et al. (2010) 91 10 *4/*4, *4/*41, *1/*5, *2/*5 16 NR (mean DFS = 95, p=0.016) All others 75 NR (mean DFS = 119) x x x x CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.27 Table 10. Clinical Validity Studies in Primarily White Populations (Significant Results Highlighted; Detail in Appendix Table B) (cont’d) NR Goetz et al. (2011) 913 5 x x x x No 102 Yes Lammers et al. (2010) Misclassification n Inappropriate Confounders Study Median Follow Up, y Overfittinga Potential for Bias Survival Bias ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Metabolizer Status Accounted for CYP2D6 Inhibitors? Comparator Referent Other Outcome Genotype n Genotype n V/V for *3, *4, or *6 13 wt/wt + IM (see Table B) 48 V/V V/v V/wt V = *3, *4, *5, *6 v = *10, *17, *41 48 52 292 wt/wt wt/wt wt/wt HR for RFS/DFS (95% CI) Type TTR 372 372 372 HR (95% CI) Univariate NR (K-M V/V 1.4 y, 0.7 to 2.2, vs. wt/wt + IM 1.8, 1.4 to 2.3, p=0.089) OS (K-M V/V 5.0 y, 4.1 to 5.9, vs. wt/wt+ IM 7.9, 6.2 to 9.5, p=0.012) BCI OR = 0.9 (0.5 to 1.7) OR = 1.5 (0.8 to 2.7) OR = 0.9 (0.7 to 1.3) Technology Evaluation Center 28 Table 10. Clinical Validity Studies in Primarily White Populations (Significant Results Highlighted; Detail in Appendix Table B) (cont’d) 8 x x No 265 Misclassification Sestak et al. (2012) Inappropriate Confounders n Overfittinga Study Median Follow Up, y Survival Bias Potential for Bias Yes CYP2D6 Metabolizer Status Accounted for CYP2D6 Inhibitors? Comparator Referent Other Outcome Genotype n Genotype n PM=V/V IM=V/v or v/v PM + IM 18 29 47 wt/wt wt/wt wt/wt 218 218 218 HR for RFS/DFS (95% CI) Type HR (95% CI) BCI OR = 1.0 (0.3 to 3.3) OR = 0.8 (0.3 to 2.2) OR = 1.1 (0.5 to 2.3) V= nonfunctional allele V = reduced function allele (AmpliChipe CYP2D6 array) BCI: breast cancer incidence; wt: wild type; V: variant; IM: intermediate metabolizer; :HR: hazard ratio; CI: confidence interval; RFS: recurrence-free survival; DFS: disease-free survival; DSS: disease-specific survival; OS: overall survival; TTP: time to (disease) progression; TTR: time to (disease) recurrence; RR: relative risk; NR: not reported; KM: Kaplan-Meier; chemo: chemotherapy; TAM: tamoxifen; BCFI: breast cancer-free interval; OR: odds ratio a Authors report that selection bias (other than survival bias) could not be excluded. b Case-control study from a Danish national registry (the Danish Breast Cancer Cooperative Group) in which nearly all newly diagnosed breast cancer incident cases have been reported and registered since 1978 (Blichert-Toft et al. 2008). Per Lash et al. (2011), the same 10-year follow-up protocol was used for all patients. c CYP2D6 genotype determined from whole blood for 601 patients; unclear from publications when blood was drawn in relation to diagnosis/surgery. In addition, results from 22% of patients have been reported in previous studies. d Authors report SSRIs were “rarely used” in the patient population. e AmpliChip detects CYP2D6 alleles *1 to *10AB, *11, *14A, *14b, *15, *17, *19, *20, *25, *26, *29 to *31, *35, *36, *40, *41, *1xN, *2xN *4xN, *10xN, *17xN, *35xN, and *41xN. CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.29 Table 10. Clinical Validity Studies in Primarily White Populations (Significant Results Highlighted; Detail in Appendix Table B) (cont’d) Technology Evaluation Center significant HR estimates for time to breast cancer recurrence for patients with CYP2D6 homozygous nonfunctional alleles (PMs) and for patients with CYP2D6 reduced function (IMs) compared with patients with fully functional alleles (EMs). Several CYP2D6 allele variants were tested, and the study sample exceeded the number recommended by the power analysis. The unadjusted HR for time to recurrence for CP2D6 nonfunctional homozygotes (PMs) compared with fully functional wild types (EMs) was 2.1 (95% CI, 1.3 to 3.5; Table 10). This study combined patient samples from different sources, including some (22% of total) for which results had already been reported, although not as extensively genotyped. In addition, 601 of 1345 samples were genotyped from whole blood, but the report does not clarify when blood samples were collected relative to disease diagnosis or surgery, suggesting the potential for survival bias. Regan (2012) and Rae (2012) each reported analyses of samples from the single-agent treatment arms of completed clinical trials, the Breast International Group (BIG) 1-98 trial, and Arimidex, Tamoxifen, Alone or in Combination (ATAC) trial, respectively. These studies had the advantage of known and consistent treatment within each population, compared with the samples of convenience of many other studies, as well as large sample sizes and testing for multiple CYP2D6 variants. In neither study were HRs for recurrence significant or trending toward significance, either in tamoxifen-treated patients (Table 10) or in patients treated with AIs, tested for comparison (Appendix Table B). Regan et al. (2012) separately analyzed the majority of patients who did not receive chemotherapy (Table 10) as well as those who did (Appendix Table B), but found no difference in results. Both studies have been criticized for sampling tumor tissue rather than normal tissue and for genotyping techniques that may have increased misclassification (Pharoah et al. 2012; Stanton 2012; Brauch et al. 2013; Goetz 2013) or invalidated the results (Nakamura et al. 2012). However, the authors calculated that misclassification of 75% of EMs would have been required to change the results of the Regan et al. (2012) study and observed that similar results across all 3 phenotype groups in the Rae et al. (2012) study would likely be unaffected by misclassification. Other authors have supported the validity of the results (Berry 2013). 30 Goetz et al. (2013) evaluated a total of 319 cases and 557 matched controls (i.e., patients without a recurrence event) from a randomized controlled trial comparing 5 years of tamoxifen with 2 years of tamoxifen plus 3 years of anastrozole. Cases were matched to controls on several variables, including variables associated with breast cancer prognosis. Because such variables are neither causally related to CYP2D6 genotype nor surrogates for genotype, their use may introduce bias into comparative analyses. Exact numbers of patients in each genotypic category for comparative calculations were not reported. Results, reported as odds ratios rather than HRs, indicate that CYP2D6 PMs had significantly higher odds of disease recurrence in the 5-year tamoxifen arm, but not in the 2-year tamoxifen arm, relative to EMs. Wegman et al. (2007) genotyped 677 samples for only the *4 variant, but found no significant difference in RFS between *4/*4 PMs and *4 noncarriers. Only 2 events occurred in 35 *4/*4 patients, highlighting the necessity of large numbers for these studies. The remaining studies evaluated much smaller sample sizes (range, 85-223 for primary outcomes). Goetz et al. (2005; n=223) and Schroth et al. (2007; n=486) retrospectively enrolled relatively homogeneous populations of patients who had been treated with tamoxifen alone (no chemotherapy) following tumor resection. Goetz et al. (2005) only genotyped for the CYP2D6*4 nonfunctional variant (most common), whereas Schroth et al. (2007) also tested for the *5 nonfunctional variant and the *10 and *41 reduced function variants. Goetz et al. (2007) reported a reanalysis of Goetz et al. (2005), incorporating information on CYP2D6 inhibitor medication use to assign patient metabolizer status (not done in Schroth et al. [2007]). Both studies reported significantly reduced RFS and time to recurrence for patients homozygous for nonfunctional CYP2D6 alleles (Table 12). The analysis by Schroth et al. (2007) was inappropriately adjusted for tumor size and nodal status, which may have biased results. However, these results represent a potentially weaker effect than might otherwise have been found, because IMs are included in the decreased CYP2D6 activity group. Other studies reported both significant and not significant results for CYP2D6 genotype association with clinical outcomes of tamoxifen ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment treatment. Difficulties include low sample numbers in all studies; analyses adjusted for parameters that do not meet the definition of a confounder of the genotype-outcome association in some studies; and study designs potentially affected by survivor bias in 2 studies (see Table 10). One study grouped genotypes for comparison with no apparent rationale other than that the results became significant (Ramon y Cajal et al. 2010). The only study that reported a significant association between genotype and overall survival was in the metastatic setting (Lammers et al. 2010). This was a retrospective analysis of 102 patients with hormone receptor-positive metastatic breast cancer who were treated with tamoxifen 40 mg daily. In analyses inappropriately adjusted for age, overall survival was significantly shorter for PMs than EMs (HR for death = 2.1; 95% CI, 1.1 to 4.1). Two studies in the prophylactic setting found no association between CYP2D6 genotype and breast cancer occurrence (Goetz et al. 2011; Sestak et al. 2012). Goetz et al. (2011) conducted a case-control study of 913 women (93%) in the tamoxifen arms of the National Surgical Adjuvant Breast and Bowel Project (NSABP) P1 and P2 prevention trials. Cases developed invasive or noninvasive (DCIS) breast cancer after prophylactic treatment with tamoxifen. The study had 80% power to detect an odds ratio of 1.54 for PMs versus EMs. Sestak et al. (2012) assessed 265 women randomized to tamoxifen (20 mg daily) in the International Breast Cancer Intervention Study I (IBIS-I). IBIS-I compared 5 years of prophylactic tamoxifen therapy with placebo in high-risk women. Cases were women who developed estrogen receptor-positive invasive breast cancer. The study had 74% power to detect a 2-fold increase in cancer incidence for combined PMs and IMs compared with EMs. Both studies matched controls on prognostic variables, such as age and 5-year predicted breast cancer risk, which may have introduced selection bias. Reviewing all studies, no pattern for potential bias and significant versus nonsignificant results is apparent. Additionally, not all studies accounted for CYP2D6 inhibitor use in assigning metabolizer status, which would be most important for nonsignificant studies, as it would bias toward the null. However, studies that did not make this correction are not uniquely associated with negative results. Across all studies there was considerable variation in alleles genotyped, from only the *4 allele in some studies to as many as 7 specific variant alleles or 33 using the AmpliChip. Studies also used different schemes for assigning genotypes to metabolizer categories (Appendix Table B). In addition, smaller studies often grouped nonfunctional homozygotes and heterozygotes (i.e., PMs and IMs) together in order to have sufficient numbers for comparison, which would also bias toward the null. However, the largest studies that compared only homogeneous nonfunctional genotypes with fully functional genotypes (the most extreme comparison) reported predominately negative results. Summary. Twenty-three studies (in 24 publications) assessed the association between CYP2D6 genotype and clinical outcomes in women treated with tamoxifen. Most of these examined tamoxifen use in the adjuvant setting in postmenopausal women. Seven small studies in Asian populations focused on the CYP2D6*10 reduced function allele, and 5 reported significant results for the association of CYP2D6 genotype with outcomes of tamoxifen treatment; these studies may be affected in unpredictable ways by different types of bias. Two studies that reported no association may have less potential for bias. Of 14 studies (in 15 publications) that evaluated samples from primarily white patients, 3 large studies reported no significant association for time to recurrence. Two of these were retrospective analyses of clinical trial samples and were designed to minimize the potential for bias; their size allowed for comparison of homozygous nonfunctional CYP2D6 genotypes with fully functional wild-type genotypes, i.e., the most extreme comparison and most likely to reveal a true association. Two large positive studies introduced potential bias due to uncertain timing of tissue (blood) collection (survival bias) and inappropriate matching on prognostic factors. Smaller studies reported a variety of significant and nonsignificant results; no pattern of bias, genotyping or group scheme, or accounting for CYP2D6 inhibitor use (among possibilities) explains the differences in results. There are several limitations to this evidence: n Most studies were insufficiently powered to detect a significant association between genotype and disease recurrence comparing homozygous nonfunctional genotypes (PMs) with fully functional wild types (EMs). n There is much variability across studies in the variant alleles genotyped, in genotype ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.31 Technology Evaluation Center grouping into CYP2D6 metabolizer category, and in how categories are grouped for comparison in statistical analyses, making it difficult to compare results across studies. n In several studies, there is potential for bias, and/or only adjusted estimates of effect are reported from analyses incorporating parameters that do not meet the definition of a confounder of the genotype-outcome association. n Only 1 small study in patients with metastatic breast cancer reported a significant association between genotype and overall survival; larger studies are needed to determine effect. Two studies in the prophylactic setting found no association between CYP2D6 genotype and breast cancer incidence. The heterogeneity of results across all studies, and clear results of no genotype-tamoxifen treatment outcome in 2 large trials with the least apparent potential for bias, suggest a lack of support for clinical validity. metabolism and lower endoxifen levels compared with genotypic wild-type EMs, and as a direct result have poorer clinical outcomes. This question rests on the assumption, not yet supported by evidence, that some level of endoxifen is sufficient and necessary for tamoxifen efficacy, and that this level is not achieved in genotypic and functional CYP2D6 PMs, and possibly not in some IMs. However, because tamoxifen metabolism is complex and CYP2D6 does not appear to account for all variability in endoxifen levels, it is conceivable that polymorphisms in other tamoxifen metabolic pathway enzymes may affect active metabolite levels, and in theory direct measurement of the metabolite(s) itself might be the better predictor of benefit from tamoxifen treatment. However, because it takes 8 weeks for tamoxifen metabolites to reach steady-state concentrations, measuring metabolite levels is not practical for clinical applications. Discussion More to the point is a cautionary note by Lash et al. (2009) regarding the likely effect of CYP2D6 nonfunctional allele products on the pharmacodynamics of tamoxifen. The estrogen receptor is the binding target of tamoxifen and its metabolites, and dissociation constants of even the more weakly binding molecules, including tamoxifen itself, are still sufficient to effectively block estrogen binding (Ratliff et al. 2004). Moreover, it is estimated that at doses used for adjuvant treatment, which are intended to saturate the estrogen receptor, more than 99% of estrogen receptors are bound by tamoxifen and its metabolites (Dowsett and Haynes 2003). Lash et al. (2009) modeled the effect of CYP2D6 variant alleles on estrogen receptor binding by tamoxifen and metabolites and found negligible effect. As the authors note, however, modeling cannot account for many metabolic complexities, and mechanistic data are needed “to show how the change in metabolite-concentration profile associated with inheriting the variant alleles reduces the protection against recurrence conferred by tamoxifen therapy, despite evidence to the contrary.” For example, is there a critical threshold for endoxifen concentrations associated with tamoxifen efficacy, and do CYP2D6 variants reduce endoxifen concentrations below that threshold? The question examined in this Assessment is whether patients with CYP2D6 gene variants that result in markedly reduced or absent enzyme function have reduced tamoxifen Thus it remains to examine the clinical evidence, the bulk of which addresses clinical validity, the CYP2D6 genotype-tamoxifen treatment outcome association. As noted, study 3. In women who need endocrine therapy, does use of CYP2D6 genotype testing result in selection of endocrine therapy regimens that improve health outcomes compared with selection of endocrine therapy regimens without testing (i.e., clinical utility)? No clinical trials that provide direct evidence of clinical utility have been conducted. Such a trial might prospectively enroll patients who would be prescribed endocrine therapy including tamoxifen, but who would also be eligible for AI treatment. Patients would be randomized to usual methods of treatment selection or to CYP2D6 genotyping after which PMs would receive AI treatment alone. Currently, however, without a foundation in clinical validity, there is no basis for considering a change in management for patients with specific genotypes to improve outcomes (clinical utility). Summary. Evidence for clinical utility is currently lacking. 32 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment results were heterogeneous. Lash et al. (2009) also suggests that the estimates of effect of many studies are implausible, implying either that tamoxifen therapy is more effective than AI therapy in women with 2 functional alleles, or that tamoxifen therapy is less effective than placebo in women with no functional allele, depending on the direction of the association. Heterogeneity in effect estimates, both in size and significance or lack thereof, is likely due to the lack of power in most studies, and to potential sources of bias in some. The analysis of archived samples from 2 large completed clinical trials was undertaken to achieve adequate power, to evaluate CYP2D6 genotype more fully, to evaluate AI-treated control populations in tandem, and to avoid potential sources of bias. That the results of these studies discovered no evidence of association between CYP2D6 genotype and either tamoxifen- or AI-treated patient outcomes suggests that using the results of CYP2D6 genetic testing to influence decisions about tamoxifen treatment is not currently warranted. Strong evidence of clinical utility will likely be needed to change this recommendation. Summary of Application of the Technology Evaluation Criteria Based on the available evidence, the Blue Cross and Blue Shield Medical Advisory Panel made the following judgments about whether CYP2D6 genotyping for directing endocrine therapy regimen selection for women at high risk for primary breast cancer or breast cancer recurrence meets the Blue Cross and Blue Shield Association Technology Evaluation Center (TEC) criteria. 1. The technology must have final approval from the appropriate governmental regulatory bodies. (http://molecular.roche.com/assays/Pages/ AmpliChipCYP450Test.aspx). CYP2D6 genotyping assays are also available as laboratory developed tests (LDT). Clinical laboratories may develop and validate tests inhouse and market them as a laboratory service; laboratories offering LDTs as a clinical service must meet the general regulatory standards of the Clinical Laboratory Improvement Act (CLIA) and must be licensed by CLIA for highcomplexity testing. FDA has considered updating the label for tamoxifen (brand and generics) with information or recommendations regarding CYP2D6 genotyping and impact on tamoxifen efficacy. On October 18, 2006, FDA held an Advisory Committee meeting to answer specific questions regarding the evidence and recommendations for the label update. Since that Advisory Committee meeting, AstraZeneca, the brand name (Nolvadex®) manufacturer, has ceased producing tamoxifen and is no longer maintaining the prescribing information. As of the date of this Assessment, no direction has come from FDA regarding revised labeling of generic versions of tamoxifen to include CYP2D6 genotyping information. 2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes. There are several limitations to the overall body of evidence, but the largest, most welldesigned studies do not support clinical validity of the test. Without demonstrable clinical validity, there is no basis for changing management in patients with specific genotypes to improve outcomes (clinical utility). 3. The technology must improve the net health outcome. Evidence for clinical utility is currently lacking. The Roche AmpliChip CYP450 Test is cleared by the US Food and Drug Administration (FDA) and is “intended to identify a patient’s CYP2D6 and CYP2C19 genotype from genomic DNA extracted from a whole blood specimen. Information about CYP2D6 and CYP2C19 genotype may be used as an aid to clinicians in determining therapeutic strategy and treatment dose for therapeutics that are metabolized by the CYP2D6 or CYP2C19 gene product” 4. The technology must be as beneficial as any established alternatives. Because the available evidence does not clearly support a significant association between CYP2D6 genotype and tamoxifen treatment outcome, a chain of evidence supporting the clinical utility of CYP2D6 genotyping for directing endocrine therapy regimen selection for ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.33 Technology Evaluation Center women at high risk for or with breast cancer cannot be constructed. 5. The improvement must be attainable outside the investigational settings. The use of CYP2D6 genotyping for directing endocrine therapy regimen selection for women at high risk for or with breast cancer to improve health outcomes has not been demonstrated in the investigational setting. Based on the above, CYP2D6 genotyping does not meet the TEC criteria for directing endocrine therapy regimen selection for women at high risk for primary breast cancer or breast cancer recurrence. NOTICE OF PURPOSE: TEC Assessments are scientific opinions, provided solely for informational purposes. TEC Assessments should not be construed to suggest that the Blue Cross Blue Shield Association, Kaiser Permanente Medical Care Program or the TEC Program recommends, advocates, requires, encourages, or discourages any particular treatment, procedure, or service; any particular course of treatment, procedure, or service; or the payment or non-payment of the technology or technologies evaluated. CONFIDENTIAL: This document contains proprietary information that is intended solely for Blue Cross and Blue Shield Plans and other subscribers to the TEC Program. The contents of this document are not to be provided in any manner to any other parties without the express written consent of the Blue Cross and Blue Shield Association. 34 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment References Adjuvant Breast Cancer Trials Collaborative Group. (2007). Ovarian ablation or suppression in premenopausal early breast cancer: Results from the International Adjuvant Breast Cancer Ovarian Ablation or Suppression Randomized Trial. J Natl Cancer Inst, 99(4):516-525. Alfaro CL, Lam YW, Simpson J et al. (1999). CYP2D6 status of extensive metabolizers after multiple-dose fluoxetine, fluvoxamine, paroxetine, or sertraline. J Clin Psychopharmacol, 19(2):155-63. Alfaro CL, Lam YW, Simpson J et al. (2000). CYP2D6 inhibition by fluoxetine, paroxetine, sertraline, and venlafaxine in a crossover study: intraindividual variability and plasma concentration correlations. J Clin Pharmacol, 40(1):58-66. American Cancer Society. (2008). Breast Cancer Facts & Figures 2011-2012. Atlanta: American Cancer Society, Inc. Available at: http://www.cancer.org/cancer/breastcancer/ index. Last accessed August, 2013. ATAC (Arimidex, Tamoxifen, Alone or in Combination) Trialists’ Group, Forbes JF, Cuzick J et al. (2008). Effect of anastrozole and tamoxifen as adjuvant treatment for early-stage breast cancer: 100-month analysis of the ATAC trial. Lancet Oncol, 9(1):45-53. Aubert RE, Stanek EJ, Yao J et al. (2009). Risk of breast cancer recurrence in women initiating tamoxifen with CYP2D6 inhibitors. American Society of Clinical Oncology 2009 Annual Meeting, Abstract CRA508. Bernard S, Neville KA, Nguyen AT et al. (2006). Interethnic differences in genetic polymorphisms of CYP2D6 in the U.S. population: clinical implications. Oncologist, 11(2):126-35. Berry D. (2013). CYP2D6 genotyping and the use of tamoxifen in breast cancer. J Natl Cancer Inst, 105(17):1267-9. Beverage JN, Sissung TM, Sion AM et al. (2007). CYP2D6 polymorphisms and the impact on tamoxifen therapy. J Pharm Sci, 96(9):2224-31. Bijl MJ, van Schaik RH, Lammers LA et al. (2009). The CYP2D6*4 polymorphism affects breast cancer survival in tamoxifen users. Breast Cancer Res Treat, 118(1):125-30. Blichert-Toft M, Christiansen P, Mouridsen HT. (2008). Danish Breast Cancer Cooperative Group--DBCG: history, organization, and status of scientific achievements at 30-year anniversary. Acta Oncol, 47(4):497-505. Bonanni B, Macis D, Maisonneuve P et al. (2006). Polymorphism in the CYP2D6 tamoxifen-metabolizing gene influences clinical effect but not hot flashes: data from the Italian Tamoxifen Trial. J Clin Oncol, 24(22):3708-9 Borges S, Desta Z, Li L et al. (2006). Quantitative effect of CYP2D6 genotype and inhibitors on tamoxifen metabolism: implication for optimization of breast cancer treatment. Clin Pharmacol Ther, 80(1):61-74. Brauch H, Schroth W, Goetz MP et al. (2013). Tamoxifen use in postmenopausal breast cancer: CYP2D6 matters. J Clin Oncol, 31(2):176-80. Burstein HJ, Prestrud AA, Seidenfeld J et al. (2010). American Society of Clinical Oncology clinical practice guideline: update on adjuvant endocrine therapy for women with hormone receptor-positive breast cancer. J Clin Oncol, 28(23):3784-96. Coombes RC, Kilburn LS, Snowdon CF et al. (2007). Survival and safety of exemestane versus tamoxifen after 2-3 years’ tamoxifen treatment (Intergroup Exemestane Study): a randomised controlled trial. Lancet, 369(9561):559-70. Desta Z, Ward BA, Soukhova NV et al. (2004). Comprehensive evaluation of tamoxifen sequential biotransformation by the human cytochrome P450 system in vitro: prominent roles for CYP3A and CYP2D6. J Pharmacol Exp Ther, 310(3):1062-75. Dezentjé VO, Guchelaar HJ, Nortier JW, et al. (2009). Clinical implications of CYP2D6 genotyping in tamoxifen treatment for breast cancer. Clin Cancer Res, 15(1):15-21. Dieudonne AS, Lambrechts D, Wildiers H et al. (2013). Why should results from metastatic trials no longer matter for early-stage disease? J Clin Oncol, 31(21):2753. Dowsett M, Haynes BP. (2003). Hormonal effects of aromatase inhibitors: focus on premenopausal effects and interaction with tamoxifen. J Steroid Biochem Mol Biol, 86(3-5):255-63. Fabian C, Tilzer L, Sternson L. (1981). Comparative binding affinities of tamoxifen, 4-hydroxytamoxifen, and desmethyltamoxifen for estrogen receptors isolated from human breast carcinoma: correlation with blood levels in patients with metastatic breast cancer. Biopharm Drug Dispos, 2(4):381-90. Goetz MP. (2013). Update on CYP2D6 and tamoxifen. Clin Adv Hematol Oncol, 11(3):178-80. Goetz MP, Kamal A, Ames MM. (2008). Tamoxifen pharmacogenomics: the role of CYP2D6 as a predictor of drug response. Clin Pharmacol Ther, 83(1):160-6. Goetz MP, Knox SK, Suman VJ et al. (2007). The impact of cytochrome P450 2D6 metabolism in women receiving adjuvant tamoxifen. Breast Cancer Res Treat, 101(1):113-21. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.35 Technology Evaluation Center Goetz MP, Rae JM, Suman VJ et al. (2005). Pharmacogenetics of tamoxifen biotransformation is associated with clinical outcomes of efficacy and hot flashes. J Clin Oncol, 23(36):9312-8. Goetz MP, Schaid DJ, Wickerham DL et al. (2011). Evaluation of CYP2D6 and efficacy of tamoxifen and raloxifene in women treated for breast cancer chemoprevention: results from the NSABP P1 and P2 clinical trials. Clin Cancer Res, 17(21):6944-51. Jonat W, Gnant M, Boccardo F et al. (2006). Effectiveness of switching from adjuvant tamoxifen to anastrozole in postmenopausal women with hormonesensitive early-stage breast cancer: a meta-analysis. Lancet Oncol, 7(12):991-6. Kaufmann M, Jonat W, Hilfrich J et al. (2007). Improved overall survival in postmenopausal women with early breast cancer after anastrozole initiated after treatment with tamoxifen compared with continued tamoxifen: the ARNO 95 Study. J Clin Oncol, 25(19):2664-70. Goetz M, Suman V. (2010). Genetic polymorphisms of CYP2D6*10 and CYP2C19*2, *3 are not associated with prognosis, endometrial thickness, or bone mineral density in Japanese breast cancer patients treated with adjuvant tamoxifen. Cancer, 116(4):1007. Kiyotani K, Mushiroda T, Hosono N, et al. (2010b). Lessons for pharmacogenomics studies: association study between CYP2D6 genotype and tamoxifen response. Pharmacogenet Genomics, 20(9):565-8. Goetz MP, Suman VJ, Hoskin TL, et al. (2013). CYP2D6 metabolism and patient outcome in the Austrian Breast and Colorectal Cancer Study Group trial (ABCSG) 8. Clin Cancer Res, 19(2):500-7. Kiyotani K, Mushiroda T, Imamura CK et al. (2010a). Significant effect of polymorphisms in CYP2D6 and ABCC2 on clinical outcomes of adjuvant tamoxifen therapy for breast cancer patients. J Clin Oncol, 28(8):1287-93. Griese EU, Asante-Poku S, Ofori-Adjei D et al. (1999). Analysis of the CYP2D6 gene mutations and their consequences for enzyme function in a West African population. Pharmacogenetics, 9(6):715-23. Kiyotani K, Mushiroda T, Sasa M et al. (2008). Impact of CYP2D6*10 on recurrence-free survival in breast cancer patients receiving adjuvant tamoxifen therapy. Cancer Sci, 99(5):995-9. Griese EU, Zanger UM, Brudermanns U et al. (1998). Assessment of the predictive power of genotypes for the in-vivo catalytic function of CYP2D6 in a German population. Pharmacogenetics, 8(1):15-26. Kubota T, Yamaura Y, Ohkawa N et al. (2000). Frequencies of CYP2D6 mutant alleles in a normal Japanese population and metabolic activity of dextromethorphan O-demethylation in different CYP2D6 genotypes. Br J Clin Pharmacol, 50(1): 31–34. Grimm SW, Dyroff MC. (1997). Inhibition of human drug metabolizing cytochromes P450 by anastrozole, a potent and selective inhibitor of aromatase. Drug Metab Dispos, 25:598-602. Hartman AR, Helft P. (2007). The ethics of CYP2D6 testing for patients considering tamoxifen. Breast Cancer Res, 9(2):103. Heller T, Kirchheiner J, Armstrong VW et al. (2006). AmpliChip CYP450 GeneChip: a new gene chip that allows rapid and accurate CYP2D6 genotyping. Ther Drug Monit, 28(5):673-7. Ingelman-Sundberg M. (2005). Genetic polymorphisms of cytochrome P450 2D6 (CYP2D6): clinical consequences, evolutionary aspects and functional diversity. Pharmacogenomics J, 5(1):6-13. Ji L, Pan S, Marti-Jaun J et al. (2002). Single-step assays to analyze CYP2D6 gene polymorphisms in Asians: allele frequencies and a novel *14B allele in mainland Chinese. Clin Chem, 48(7):983-8. Jin Y, Desta Z, Stearns V et al. (2005). CYP2D6 genotype, antidepressant use, and tamoxifen metabolism during adjuvant breast cancer treatment. J Natl Cancer Inst, 97(1):30-9. Johnson MD, Zuo H, Lee KH et al. (2004). Pharmacological characterization of 4-hydroxy-Ndesmethyl tamoxifen, a novel active metabolite of tamoxifen. Breast Cancer Res Treat, 85(2):151-9. 36 Lam YW, Gaedigk A, Ereshefsky L et al. (2002). CYP2D6 inhibition by selective serotonin reuptake inhibitors: analysis of achievable steady-state plasma concentrations and the effect of ultrarapid metabolism at CYP2D6. Pharmacotherapy, 22(8):1001-6. Lammers LA, Mathijssen RH, van Gelder T, et al. (2010). The impact of CYP2D6-predicted phenotype on tamoxifen treatment outcome in patients with metastatic breast cancer. Br J Cancer, 103(6):765-71. Lash TL, Cronin-Fenton D, Ahern TP, et al. (2011). CYP2D6 inhibition and breast cancer recurrence in a population-based study in Denmark. J Natl Cancer Inst, 2011 Feb 15. [Epub ahead of print] Lash TL, Lien EA, Sorensen HT, Hamilton-Dutoit S. (2009). Genotype-guided tamoxifen therapy: time to pause for reflection? Lancet Oncol, 10(8):825-33. Lash TL, Rosenberg CL. (2010). Evidence and practice regarding the role for CYP2D6 inhibition in decisions about tamoxifen therapy. J Clin Oncol, 28(8):1273-5. Lee K-H, Ward BA, Desta Z et al. (2003). Quantification of tamoxifen and three metabolites in plasma by highperformance liquid chromatography with fluorescence detection: application to a clinical trial. Journal of Chromatography B, 791(1–2):245-53. Lim HS, Ju Lee H, Seok Lee K et al. (2007). Clinical implications of CYP2D6 genotypes predictive of tamoxifen pharmacokinetics in metastatic breast cancer. J Clin Oncol, 25(25):3837-45. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment Lim YC, Desta Z, Flockhart DA et al. (2005). Endoxifen (4-hydroxy-N-desmethyl-tamoxifen) has anti-estrogenic effects in breast cancer cells with potency similar to 4-hydroxy-tamoxifen. Cancer Chemother Pharmacol, 55(5):471-8. Lim YC, Li L, Desta Z et al. (2006). Endoxifen, a secondary metabolite of tamoxifen, and 4-OH-tamoxifen induce similar changes in global gene expression patterns in MCF-7 breast cancer cells. J Pharmacol Exp Ther, 318(2):503-12. Lonning PE. (2007). Adjuvant endocrine treatment of early breast cancer. Hematol Oncol Clin North Am, 21(2):223-38. Loprinzi CL, Kugler JW, Sloan JA et al. (2000). Venlafaxine in management of hot flashes in survivors of breast cancer: a randomised controlled trial. Lancet, 356(9247):2059-63. Lynch T, Price A. (2007). The effect of cytochrome P450 metabolism on drug response, interactions, and adverse effects. Am Fam Physician, 76(3):391-6. Newman WG, Hadfield KD, Latif A et al. (2008). Impaired tamoxifen metabolism reduces survival in familial breast cancer patients. Clin Cancer Res, 14(18):5913-8. Nowell SA, Ahn J, Rae JM et al. (2005). Association of genetic variation in tamoxifen-metabolizing enzymes with overall survival and recurrence of disease in breast cancer patients. Breast Cancer Res Treat, 91(3):249-58. Okishiro M, Taguchi T, Jin Kim S et al. (2009). Genetic polymorphisms of CYP2D6 10 and CYP2C19 2, 3 are not associated with prognosis, endometrial thickness, or bone mineral density in Japanese breast cancer patients treated with adjuvant tamoxifen. Cancer, 115(5):952-61. Pharoah PD, Abraham J, Caldas C. (2012). Re: CYP2D6 genotype and tamoxifen response in postmenopausal women with endocrine-responsive breast cancer: the Breast International Group 1-98 trial and re: CYP2D6 and UGT2B7 genotype and risk of recurrence in tamoxifentreated breast cancer patients. J Natl Cancer Inst, 104(16):1263-4; author reply 6-8. Marsh S, McLeod HL. (2007). Pharmacogenetics and oncology treatment for breast cancer. Expert Opin Pharmacother, 8(2):119-27. Rae JM, Drury S, Hayes DF, et al. (2012). CYP2D6 and UGT2B7 genotype and risk of recurrence intamoxifentreated breast cancer patients. J Natl Cancer Inst, 104(6):452-60. Mauriac L, Keshaviah A, Debled M et al. (2007). Predictors of early relapse in postmenopausal women with hormone receptor-positive breast cancer in the BIG 1-98 trial. Ann Oncol, 18(5):859-67. Rae JM, Regan MM, Thibert JN et al. (2013). Concordance between CYP2D6 genotypes obtained from tumor-derived and germline DNA. J Natl Cancer Inst, 105(17):1332-4. Mortimer JE, Flatt SW, Parker BA et al. (2007). Tamoxifen, hot flashes and recurrence in breast cancer. Breast Cancer Res Treat, 108(3):421-6. Ramon y Cajal T, Altes A, Pare L et al. (2010). Impact of CYP2D6 polymorphisms in tamoxifen adjuvant breast cancer treatment. Breast Cancer Res Treat, 119(1):33-8. Mouridsen H, Giobbie-Hurder A, Goldhirsch A, et al for the BIG 1-98 Collaborative Group. (2009). Letrozole therapy alone or in sequence with tamoxifen in women with breast cancer. N Engl J Med, 361(8):766-76. Reddy P. (1998). A review of the newer aromatase inhibitors in the management of metastatic breast cancer. J Clin Pharm Ther, 23(2):81-90. Myrand SP, Sekiguchi K, Man MZ, et al. (2008). Pharmacokinetics/genotype associations for major cytochrome P450 enzymes in native and first- and thirdgeneration Japanese populations: comparison with Korean, Chinese, and Caucasian populations. Clin Pharmacol Ther, 84(3):347-61. Nakamura Y, Ratain MJ, Cox NJ et al. (2012). Re: CYP2D6 genotype and tamoxifen response in postmenopausal women with endocrine-responsive breast cancer: The Breast International Group 1-98 Trial. Journal of the National Cancer Institute, 104(16):1264. National Comprehensive Cancer Network (NCCN). (2013). Clinical Practice Guidelines in Oncology™: Breast Cancer V.3.2013. Available at http://www.nccn.org/ professionals/physician_gls/pdf/breast.pdf. Last accessed August 2013. National Comprehensive Cancer Network (NCCN). (2013). Clinical Practice Guidelines in Oncology™: Breast Cancer Risk Reduction V.1.2013. Available at http://www. nccn.org/professionals/physician_gls/pdf/breast_risk.pdf. Last accessed August 2013. Regan MM, Leyland-Jones B, Bouzyk M, et al. (2012). CYP2D6 genotype and tamoxifen response in postmenopausal women with endocrine-responsive breast cancer: The Breast International Group 1-98 Trial. J Natl Cancer Inst, 104(6):441-51. Sachse C, Brockmöller J, Bauer S et al. (1997). Cytochrome P450 2D6 variants in a Caucasian population: allele frequencies and phenotypic consequences. Am J Hum Genet, 60(2):284-95. Schroth W, Antoniadou L, Fritz P et al. (2007). Breast cancer treatment outcome with adjuvant tamoxifen relative to patient CYP2D6 and CYP2C19 genotypes. J Clin Oncol, 25(33):5187-93. Schroth W, Goetz MP, Hamann U et al. (2009). Association between CYP2D6 polymorphisms and outcomes among women with early stage breast cancer treated with tamoxifen. JAMA, 302(13):1429-36. Sestak I, Kealy R, Nikoloff M et al. (2012). Relationships between CYP2D6 phenotype, breast cancer and hot flushes in women at high risk of breast cancer receiving prophylactic tamoxifen: results from the IBIS-I trial. Br J Cancer, 107(2):230-3. ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.37 Technology Evaluation Center Sproule BA, Otton SV, Cheung SW et al. (1997). CYP2D6 inhibition in patients treated with sertraline. J Clin Psychopharmacol, 17(2):102-6. Stanton V, Jr. (2012). Re: CYP2D6 genotype and tamoxifen response in postmenopausal women with endocrineresponsive breast cancer: the Breast International Group 1-98 trial. J Natl Cancer Inst, 104(16):1265-6; author reply 6-8. Stearns V, Johnson MD, Rae JM et al. (2003). Active tamoxifen metabolite plasma concentrations after coadministration of tamoxifen and the selective serotonin reuptake inhibitor paroxetine. J Natl Cancer Inst, 95(23):1758-64. Toyama T, Yamashita H, Sugiura H et al. (2009). No association between CYP2D6*10 genotype and survival of node-negative Japanese breast cancer patients receiving adjuvant tamoxifen treatment. Jpn J Clin Oncol, 39(10):651-6. Wegman P, Elingarami S, Carstensen J et al. (2007). Genetic variants of CYP3A5, CYP2D6, SULT1A1, UGT2B15 and tamoxifen response in postmenopausal patients with breast cancer. Breast Cancer Res, 9(1):R7. Wegman P, Vainikka L, Stal O et al. (2005). Genotype of metabolic enzymes and the benefit of tamoxifen in postmenopausal breast cancer patients. Breast Cancer Res, 7(3):R284-90. Xu Y, Sun Y, Yao L et al. (2008). Association between CYP2D6 *10 genotype and survival of breast cancer patients receiving tamoxifen treatment. Ann Oncol, 19(8):1423-9. Young D. (2006). Genetics examined in tamoxifen’s effectiveness: recurrence warning urged for labeling. Am J Health Syst Pharm, 63(23):2286, 2296. 38 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. CYP2D6 Pharmacogenomics of Tamoxifen Treatment Appendix ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.39 ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. – TAM Use –Dose Study n Lim et al. (2007) AHRQ 21 Study Design, Patients Retrospective cohort Korean pre- and postmenopausal women with metastatic breast cancer taking TAM + prior chemo and/ or AI Kiyotani et al. (2008) 67 Pre- and postmenopausal patients with ER+ invasive breast cancer. Crosssectional selection from surgical patients receiving tamoxifen monotherapy 1986 2006, seen again Sep–Nov 2007 –Duration –Median Patient Follow-Up Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample –Treatment of metastatic disease – 20 mg/d –Median Yes CYP2D6 (*5,*10) Comparison, n Results *10/*10 (12) vs. wt/wt or wt/*10 (n=9) Patients experiencing complete or partial response, or stable disease at ≥24 mo: wt/wt or wt/*10 patients: 9 of 9 (100%) 6 of 12 (50%) *10/*10 patients: Median time to progression: wt/wt or wt/*10 patients: 21.8 mo 5.03 (p=0.003) *10/*10 patients: Whole blood collected at follow-up 9 (range, 2–23+) mo –Median 1.6 (range, 0.6–4.5) y –Adjuvant – 20 mg/d – 5 y – 10 y Univariate HR for time to progression 3.69 ( 95% CI, 1.28 to 10.67) No patients were treated with SSRIs CYP2D6 (*4, *5, *6, *10, *14, *18, *21, *41) Whole blood collected Sep- Nov 2007 PM (n=15) [*10/*10] Frequency of all other tested genotypes except those listed as PM or EM was collectively 13% and not further studied EM (n=43) [wt/wt, wt/*10] PM vs. EM, OR for recurrence = 6.65 (95% CI, 1.68 to 26.4) PM vs. EM, HR for RFS = 8.67 (95% CI, 1.06 to 71.09) in univariate analysis Technology Evaluation Center 40 Table A. Association of Genotype With Clinical Outcome in Patients of Asian Ethnicity and CYP2D6*10 Major Variant Study n Xu et al (2008) 152 Toyama et al. (2009) 154 Study Design, Patients Pre- and postmenopausal women with newly diagnosed breast cancer receiving surgery and starting tamoxifen monotherapy Dec 1994– Nov 2005, Pre- and postmenopausal consecutive patients with primary LN-negative invasive breast cancer receiving tamoxifen monotherapy – TAM Use –Dose –Duration –Median Patient Follow-Up –Adjuvant – 20 mg/d –NR – 5.25 y –Adjuvant – 20 mg/d –3.2 (range, 2–5) y –7.9 (range, 2.1–20.8) y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Comparison, n Results No patients were treated with known inhibitors of CYP2D6 CYP2D6 (*10) PM (n=28) [*10/*10] Whole blood, fresh-frozen tumor, or paraffinembedded negative axillary LN EM (n=124) [wt/wt, wt/*10] Multivariate analyses adjusted for age, clinical stage, LN, tumor size, adjuvant therapy, surgery, HER-2, and hormone receptor status; in separate analyses, CYP2D6 genotype was not significantly associated with any of these features CYP2D6 (*10) *10/*10 (n=28) vs. wt/*10 (n=62) vs. wt/wt (n=64) NR Fresh-frozen tumor tissue Genotype PM EM 5-Year DFS, % 89 96 HR for HR for 5-Year DSSa 5-Year DFSa 4.7 (1.1 to 20) 2.7 (0.4 to 17.3) ReferenceReference Among 141similar patients who did not receive tamoxifen, the CYP2D6*10 genotype was not associated with DFS or DSS a 95% CI. No correlation between CYP2D6*10 genotype and prognostic features No association between CYP2D6*10 genotype and DFS or OS by Kaplan-Meier analysis and log-rank verification CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.41 Table A. Association of Genotype With Clinical Outcome in Patients of Asian Ethnicity and CYP2D6*10 Major Variant (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. – TAM Use –Dose Study n Okishiro et al. (2009) 173 Kiyotani et al. (2010a) (update of Kiyotani et al. 2008) 282 –Duration –Median Patient Follow-Up Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Pre- and postmenopausal consecutive hormone receptor positive breast cancer surgical patients treated with TAM from 1998–2004; 58% also received chemo and/or goserelin –Adjuvant – 20 mg/d –4.3 (range, 0.75–5) y –4.7 (range, Patients receiving SSRIs were excluded CYP2D6 (*10) Cross-sectional selection of pre- and postmenopausal surgical patients with ER+ invasive breast cancer receiving TAM 1986–2007, seen again Sep 2007– Apr 2009 –Adjuvant – 20 mg/d – 5 y –7.1 (range, 0.8–23.5) y Study Design, Patients 0.7–9.1) y No patients were treated with SSRIs Whole blood, drawn at surgery CYP2D6 (*1 = wt; variant alleles V: *4, *6, *10, *14B, *18, *21, *36, *41) Whole blood collected Sep 2007– Apr 2009 Comparison, n Results *10/*10 (40) vs. wt/wt or wt/*10 (n=133) None of the genotypes (wt/wt, *10/wt, or *10/*10) showed any significant association with various prognostic features e.g. tumor size, lymph node status, HR status, histologic grade V/V (n=63) or wt/V (n=136) Genotype Adjusted RFS HR (95% CI)a V/V 9.52 (2.79 to 32.45) wt/V 4.44 (1.31 to 15.0) wt/wt (reference) 1.0 a Adjusted for tumor size and nodal status. vs. wt/wt (n=83) RFS not significantly different between *10/*10 and other patients (log-rank p=0.98); adjustment for well-established prognostic factors did not change conclusions Technology Evaluation Center 42 Table A. Association of Genotype With Clinical Outcome in Patients of Asian Ethnicity and CYP2D6*10 Major Variant (cont’d) – TAM Use –Dose Study n Kiyotani et al. (2010b) 167 (compare with no chemo, see Kiyotani et al. (2010 a) Study Design, Patients Pre- and postmenopausal, hormone receptor positive, LN +/breast cancer patients treated with TAM + chemo combo therapy –Duration –Median Patient Follow-Up Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample NR NR CYP2D6 (*1, *4, *5, *10, *21, *36, *41) Sample NR Comparison, n Results V/V: *5/*5, *10, *21; *10/*10, *21; *21/*41 (n=33) Genotype V/V wt/V wt/wt (reference) wt/V: *1/*4, *5, *10, *36, *41 (n=85) wt/wt: *1/*1 (n=49) Adjusted RFS HR (95% CI)a 0.64 (0.2 to 1.99) 1.05 (0.48 to 2.27) 1.0 No significant association of CYP2D6 genotype with RFS in either LN+ or LN- subgroups. No significant association of CYP2D6 genotype with RFS in subgroups by tumor size (<2 cm vs. >2 cm). a Adjusted for tumor size and nodal status. TAM, tamoxifen; chemo, chemotherapy; AI, aromatase inhibitor; V, variant; wt, wild type (*1 or *2); EM, extensive metabolizer; IM, intermediate metabolizer; PM, poor metabolizer; HR, hazard ratio; OR, odds ratio; TTR, time to recurrence; RFS, recurrence-free survival; OS, overall survival; DSS, disease-specific survival; NS, not significant; SSRI, selective serotonin reuptake inhibitor; LN, lymph node; PVI, peritumoral vascular invasion; NR, not reported; CI, confidence interval CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.43 Table A. Association of Genotype With Clinical Outcome in Patients of Asian Ethnicity and CYP2D6*10 Major Variant (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. – TAM Use –Dose Study n Lash et al. (2011) 991 Study Design, Patients Case-control study from a Danish national registry of women with stage I (2%), II (46%), or III (52%) breast cancer (ER+, TAM-treated subgroup only) who were age <70 years at the time of diagnosis; cases had local or distant breast cancer recurrence or contralateral breast cancer occurrence during follow-up; 94% postmenopausal –Duration –Median Follow-Up –Adjuvant –Tam dose not reported –46% at 1 y, 18% at 2 y, 36% at 5 y –Median followup not reported; registry follows patients for 10 y; 66% enrolled >10 y before data cutoff Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Yes, prescription for SSRI or other CYP2D6 inhibitor recorded in 35%; results unchanged when analyzed by CYP2D6 phenotype CYP2D6*4 Formalinfixed, paraffin embedded tumor; substudy in 106 patients showed perfect concordance between DNA extracted from LN and DNA from tumor tissue Comparison, n Results PM (n=71) [homozygous *4] Logistic regression adjusted for time to recurrence (cases) or selection (controls), menopausal status, stage, receipt of chemotherapy, receipt of radiation therapy, and type of surgery (breast-conserving or mastectomy). IM (n=313) [wt/*4] EM (n=607) [wt/wt] Genotype PM IM EM (Reference) TTR HR (95% CI) 1.4 (0.8 to 2.3) 1.0 (0.8 to 1.3) 1.0 Technology Evaluation Center 44 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations – TAM Use –Dose Study n Schroth et al. (2009) 1,345 Study Design, Patients Consecutively collected retrospective German primary breast cancer cohort (stage I, II, or III) treated with adjuvant tamoxifen monotherapy, and patients from the tamoxifen-only arm of the NCCTG 89-30-52 trial (see Goetz 2005); 95.4% postmenopausal –Duration –Median Follow-Up –Adjuvant – 20 mg/d – 5 y – 6.3 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample No, information on comedication not available CYP2D6 (*3, *4, *5, *10, *41) Whole blood (n=601), fresh- frozen tumor (n=101), or formalinfixed, paraffin embedded tumor (n=659) Comparison, n Results PM (n=79) [homozygous or compound heterozygous for *3, *4, or *5] Recurrence All-Cause Genotype Rate (%) Mortality Rate (%) PM29.022.8 IM20.918.0 EM14.916.7 IM (n=637) [homozygous *10 or *41 or either variant + a PM allele] EM (n=629) Absence of PM or IM alleles Genotype PM IM EM (Reference) a vs. EM TTR HR (95% CI)a 2.1 (1.3 to 3.5) 1.5 (1.1 to 2.0) 1.0 CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.45 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. – TAM Use –Dose Study n Regan et al. (2012) 1,243 Study Design, Patients Postmenopausal patients with ER+ breast cancer from the Breast Inter-national Group (BIG) 1-98 trial who received tamoxifen singleagent therapy; 98% white; 57% nodenegative; 77% no chemotherapy –Duration –Median Follow-Up –Adjuvant – 20 mg/d – 5 y – 6.3 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample No CYP2D6 (*3, *4, *6, *7, *41) DNA isolated from freshfrozen paraffinembedded tumor tissue Comparison, n Results PM (n=112) homozygous or compound heterozygous for *3, *4, *6, or *7 Adjusted for LN, tumor size and grade, HER2, Ki-67, PVI, race, local therapy: IM (n=354) homozygous for *10, *17, or*41 or heterozygous for reduced and null function alleles, or heterozygous for 1 reduced or null function allele Geno-Tamoxifen [Letrozole] n EventsHR (95% CI) type n EventsHR (95% CI) No chemotherapy PM 86 8 .58 (.28 to 1.21) 99 11 .95 (.50 to 1.80) IM 277 40 .95 (.50 to 1.40) 296 37 1.02 (.69 to 1.53) EM 61075 1 63972 1 p value 0.35 0.98 Chemotherapy PM 26 3 IM 77 12 EM 16737 .76 (.23 to 2.48 25 3 .57 (.29 to 1.10) 66 12 1 16923 1.00 (.30 to 3.35) 1.68 (.83 to 3.39) 1 Analysis of *4 genotype alone in tamoxifen users, no chemo: EM (n=777) Absence of null or reduced function alleles [Unclear, n=138] Genotype *4/*4 *4/wt wt/wt n 76 168 609 Events 7 22 60 HR (95% CI) 0.57 (.26 to 1.23) 1.01 (.66 to 1.56) 1 p=0.34 Technology Evaluation Center 46 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) n Rae et al. (2012) 588 Study Design, Patients Postmenopausal patients with breast cancer from the Arimidex, Tamoxifen, Alone or in Combination (ATAC)-UK trial who received tamoxifen singleagent therapy –Adjuvant – 20 mg/d – 5 y – 10 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Yes; analysis controlled for potent CYP2D6 inhibitors, saw no effect in the ~9% of women taking drugs known to be potent inhibitors CYP2D6 variants tested (assigned points per tested allele): *1 (1), *2 (1), *3 (0), *4 (0), *6 (0), *10 (0.5), *41 (0.5) Comparison, n Results PM = 0 points HR for outcome: any recurrence including local recurrence and contralateral cancer; not adjusted IM = 0.5-1.5 EM = 2 876 Retrospective genotyping of postmenopausal women with early-stage breast cancer in the Austrian Breast and Colorectal Study 8 randomized to tamoxifen for 5 y or tamoxifen for 2 y plus anastrazole for 3 y –Adjuvant – 20 mg/d –5 y or 2 y plus anastrazole for 3 y – 5 y No CYP2D6 (*3, *4, *6, *10, *41) Paraffinembedded whole tissue TamoxifenAnastrozole HR (95% CI) p HR (95% CI) p 1.00 (referent) 1.00 (referent) 2.15 (0.85-5.40) .10 1.49 (0.33-6.64) .60 0.94 (0.43-2.08) .88 1.28 (0.43-3.78) .66 0.68 (0.23-1.96) .47 0.88 (0.22-3.53) .86 0.99 (0.48-2.08) .99 1.83 (0.66-5.02) .24 Analysis of *4 genotype alone for distant recurrence in tamoxifen users: Paraffinembedded tissue samples Goetz et al. (2013) Genotype PM (0 points) IM (0.5) IM (1) IM (1.5) EM (2) *4/*4 0.71 (0.26 to 2.00) p=0.48 *4/wt 1.18 (0.75 to 1.88) p=0.51 wt/wt1 PM (V/V) IM (V/v, V/wt, v/v or v/wt) EM (wt/wt) V = *3, *4, or *6 V = *10 or *41 OR for outcome: documented local, regional, or distant recurrence, contralateral breast cancer, second nonbreast primary cancer, or death from any cause Tamoxifen for 5 Years Genotype OR (95% CI) 2.45 (1.05-5.73) V/V V/v or V/wt 1.67 (0.95-2.93) v/v or v/wt 1.23 (0.58-2.61) wt/wt 1.0 (referent) Tamoxifen for 2 Years Plus Anastrozole Genotype OR (95% CI) V/V 0.60 (0.15 to 2.37 V/v or V/wt 0.76 (0.43 to 1.31) v/v or v/wt 1.02 (0.52 to 2.01) wt/wt 1.0 (referent) p Value 0.04 0.07 0.60 for 3 Years p Value 0.47 0.32 0.96 CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.47 Study – TAM Use –Dose –Duration –Median Follow-Up ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Study n Wegman et al. (2007) 677 Study Design, Patients Retrospective analysis of archived samples, Postmenopausal ER+ breast cancer patients with stage II or III disease (238 randomized to 2 vs. 5 y TAM) – TAM Use –Dose –Duration –Median Follow-Up –Adjuvant –20 or 40 mg/d – 2 or 5 y –7.1 (range, 0.04–18) y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample No CYP2D6 (*4) (SSRIs “rarely used in study population”) Fresh-frozen tumor tissue Comparison, n Results *4/*4 (35) or wt/*4 (186) vs. wt/wt (475) In analysis of all patients, *4 homozygotes (p=0.05) and heterozygotes (p=0.04) were significantly associated with improved RFS by K-M log-rank but results were not significant in multivariate analysis (p=0.055). Multivariate analysis (controlled for tumor stage and size, lymph node status) of each randomized subgroup was not significant for a difference in RFS, comparing *4 carriers to homozygous wt. Note: Only 2 events occurred in 35 *4/*4 patients. Technology Evaluation Center 48 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) Study n Goetz et al. (2005) 223 Goetz et al. 2007) (reanalysis of Goetz et al. 2005) 171 Study Design, Patients – TAM Use –Dose –Duration –Median Follow-Up Retrospective analysis of archived samples from NCCTG RCT (89-30-52), TAM-only arm (no chemo); all patients postmenopausal –Adjuvant – 20 mg/d – 5 y –11.4 (range, 5.7–14.1) y Retrospective analysis of archived samples from NCCTG RCT (89-30-52), TAM-only arm (no chemo); all patients postmenopausal –Adjuvant Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample No CYP2D6 (*4,*6) Paraffinembedded tissue Comparison, n Results *4/*4 (13) vs. wt/*4 (40) or wt/wt (137) Cox HR unadjusted size: RFS: HR = 2.7, 95% CI, 1.2to 6.4 p=0.023 OS: HR = 1.73, 95% CI, 0.8to 3.8 p=0.78 Unadjusted RFS and RFS results were significant. (no *6 alleles detected) – 20 mg/d – 5 y –Mean 11.4 (range, 5.7–14.1) y Yes 171 of original 223 CYP2D6*4 genotyped patients had medication information; of these, 6% were coadministered a CYP2D6 inhibitor for 2–3 y CYP2D6 (*4) Paraffinembedded tissue PM (n=16) [*4/*4 or *4/ wt + weak/mod. inhibitor or wt/ wt + potent inhibitor] or IM (n=40) [*4/wt or wt/ wt + weak/mod. inhibitor] vs. EM (n=115) [wt/wt] Cox HR (adjusted for tumor size and nodal status), PM or IM vs. EM: TTR: HR = 1.91; 95% CI, 1.05 to 3.45; p=0.034 RFS: HR = 1.74; 95% CI, 1.10 to 2.74; p=0.017 OS: HR = 1.34; 95% CI, 0.83 to 2.16; p=0.223 Cox unadjusted HR, PM vs. EM: TTR: HR = 3.20; 95% CI, 1.37 to 7.55; p=0.007 RFS: HR = 2.69; 95% CI, 1.34 to 5.37; p=0.005 OS: HR = 2.00; 95% C,I 0.92 to 4.17; p=0.077 Cox unadjusted HR, IM vs. EM: TTR: HR = 1.40; 95% CI, 0.68 to 3.05; p=0.337 RFS: HR = 1.63; 95% CI, 0.95 to 2.78; p=0.075 OS: HR = 1.40; 95% CI, 0.80 to 2.43; p=0.240 CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.49 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. n Wegman et al. (2005) 226 Study Design, Patients Retrospective analysis of archived samples from a TAM RCT + chemo or radiotherapy –Adjuvant – 40 mg/d – 2 y –10.7 (range, 0.24–18.6 y) Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample No CYP2D6 (*4) Fresh-frozen tumor tissue Comparison, n Results TAM treated vs. no TAM, stratified by*4/*4 (4) or *4/wt (43) and wt/wt (109) RFS of ER-positive and ER-negative women ( who likely did not receive TAM) did not differ significantly by genotype; authors concluded that CYP2D6*4 has no prognostic value wt/wt: *4 carrier: Postsurgery, postmenopausal breast cancer patients with positive nodes or tumor >30 mm for whom tissue was available Nowell et al. (2005) Retrospective cohort, pre- and postmenopausal 162 Primary breast cancer patients taking TAM, + chemo or radiotherapy 175 Primary breast cancer patients not taking TAM, ± chemo, radiotherapy Recurrence rate ratio (RR) for ER-positive patients, TAM treated vs. no TAM, adjusted for age, tumor size, and lymph node status: RR=0.91, 95% CI, 0.53 to 1.57, p=0.75 RR=0.28, 95% C,I 0.11 to 0.74, p=0.009 Authors reported selection bias could not be excluded. –Adjuvant –(Dose not reported) –(Duration not reported) – 5.4 y No CYP2D6 (*3,*4,*6) Paraffinembedded archived tissue *4/*4 or wt/*4 (+TAM, 49; -TAM, 46) vs. wt/wt (+TAM, 112; -TAM, 120) Survival of patients with at least 1 *4 allele (*3 and *6 alleles were rare) compared to wt/wt evaluated using Cox modeling, adjusting for age, race, stage, ER and PR status. TAM RFS OS No TAM RFS OS HR 0.67 0.77 0.69 0.79 95% CI 0.33 to 1.35 0.32 to 1.81 0.40 to 1.18 0.42 to 1.26 p Value 0.19 0.51 0.19 0.26 Technology Evaluation Center 50 Study – TAM Use –Dose –Duration –Median Follow-Up Study – TAM Use –Dose –Duration –Median Follow-Up Study Accounted for CYP2D6 Inhibitors? Retrospective cohort analysis of archived samples from pre- and postmenopausal patients –Adjuvant –(Dose not reported) –(Duration not reported) –5.9 (range, No 206 Primary breast cancer patients taking TAM alone 0.7–19 y) 280 Control breast cancer patients not taking TAM; + chemo n Schroth et al. (2007) Study Design, Patients Gene (Typed Variants)/ Sample CYP2D6 (*4,*5,*10, *41) Formalinfixed, paraffinembedded tumor tissue Comparison, n Results V/V (30) or wt/*4 or wt/*5 (49) vs. wt/wt or wt/*10 or wt/*41 (118) Cox adjusted (tumor size and nodal status) HR of TAM-treated patients with decreased vs. normal CYP2D6 activity: TTR: HR = 2.24; 95% CI, 1.16 to 4.33; p=0.02 RFS: HR = 1.89; 95% CI, 1.10 to 3.25; p=0.02 There were no significant associations with OS. There were no significant associations between genotype and outcomes in patients not treated with TAM (chemo not accounted for). The p values of risk estimates were adjusted for multiple comparisons CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.51 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Study n Newman et al. (2008) 115 90 Study Design, Patients Unrelated white women with complete clinical data from a cohort of probands with pathogenic BRCA1 or BRCA2 mutations at 1 UK cancer genetics center + Ethnically matched control population without cancer – TAM Use –Dose –Duration –Median Follow-Up –Adjuvant – 20 mg/d – >4 y – 10 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Yes CYP2D6 (*3, *4, *41, and *5 deletion) Use of CYP2D6 inhibitors accounted for in assigning metabolizer status Baseline germ-line DNA samples extracted from lymphocytes Comparison, n Results PM (n=12) [homozygous or compound heterozygous for *3, *4, or *5; or wt/wt + potent inhibitor or wt/*3, *4, or *5 + moderate inhibitor] No significant differences between allele and genotype frequencies in control and patient populations, i.e., CYP2D6 not associated with breast cancer in patients with BRCA mutations IM (n=7) [*41/*41 or *41/*3, *4, or *5 ] EM (n=96) [wt/wt/ or wt/*3, *4, *5, or *41 and no inhibitor Genotype PM EM MedHRa for TTR, y Recurrenceb HR for OSb 5.2 2.1 (0.84 to 5.4) 2.5 (0.8 to 8.2) 17.3Reference Reference PM BRCA2 EM BRCA2 4.1 19.3 3.8 (1.0 to 14.5) Reference PM BRCA1 NR 1.3 (0.3 to 6.2) EM BRCA1 NR Reference a Adjusted for nodal status. b 95% CI. 9.7 (2.3 to 41.0) Reference [No deaths] Technology Evaluation Center 52 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) Study n Bijl et al. (2009) 85 Ramon y Cajal et al. (2010) 91 Study Design, Patients – TAM Use –Dose –Duration –Median Follow-Up All women in a population-based cohort study who received a first prescription of tamoxifen from 1991–2005 –Adjuvant – 20 mg/day – >4 years – 10 years Pre- and postmenopausal patients diagnosed with primary invasive breast cancer 1996–1998 and returned to hospital for follow-up in 2007; patients treated with either tamoxifen alone or plus chemo –Adjuvant – 20 mg/d – >4 y – 10 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Comparison, n Results Yes CYP2D6 (*4) PM (n=4) [*4/*4] Isolated DNA from baseline sample IM ( n= 29) [*1/*4] GenotypeHR a for Breast Cancer Mortality PM 4.1 (1.1 to 15.9) IM 1.9 (0.9 to 3.9) EM (reference) 1.0 CYP2D6 (33 alleles by AmpliChipc CYP2D6 array) 1) PM/PM, PM/ IM (n=10) No significant correlation found between genotypes and clinical prognostic variables 2) IM/IM, EM/ PM, EM/IM (n=50) Genotype Whole blood at follow-up 3) EM/EM, UM/ EM, UM/IM (n=31) CYP2D6 inhibitors administered in 11 patients; analyzed as potential confounders No Information on CYP2D6 inhibitor medication was incomplete HR a for AllCause Mortality 1.9 (0.6 to 4.6) 1.5 (0.8 to 2.8) 1.0 Adjusted for age, tamoxifen dose and duration, and calendar time. 95% CI. a EM (n=52) [*1/*1] See study for genotype classifications Mean BetweenDFS, mo Group p Values 1 98 2 114 31180.41 95 *4/*4, *4/*41 *1/*5, *2/*5 All others 119 0.016 CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.53 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Study n Lammers et al. (2010) 102 Study Design, Patients All patients from a consecutive series treated with TAM between 1986 and 2008 who had ER+ metastatic breast cancer – TAM Use –Dose –Duration –Median Follow-Up –Nonadjuvant – 40 mg/d –2.8 y (range, 1.6 mo to 17 y) – Not reported Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Yes, charts reviewed for use of CYP2D6 inhibitors, incorporated into phenotype CYP2D6 (*3, *4, *5, *6, *10, *41) Whole blood collected at follow-up Comparison, n Results PM: 2 null alleles (*3, *4, *5, or *6) or 1 null allele + moderate inhibitor or wt + potent inhibitor Phenotypen PM 13 IM 38 EM 48 IM: homozygous for reduced function allele (*10 or *41) or heterozygous for reduced/ null function alleles or for wt/ null alleles + no inhibitor or wt/ wt + weak-mod inhibitor EM: wt/wt + no inhibitor a HRa for TTR 1.69 (.9 to 3.19) 0.99 (.64 to 1.55) 1 Reference n 12 22 33 HRa for OS 2.09 (1.06 to 4.12) 0.87 (.50 to 1.50) 1 Reference Adjusted for age. 95% CI. Phenotype PM EM + IM a 95% CI. n 13 48 K-M Survival (95% CI), y 5.0 (4.1 to 5.9) 7.9 (6.2 to 9.5), p=0.012 Technology Evaluation Center 54 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) Study n Goetz et al. (2011) 913 Study Design, Patients Case-control study of 93% of women enrolled in the tamoxifen arms of the National Surgical Adjuvant Breast and Bowel Project (NSABP) P1 and P2 prevention trials who were age ≥50 y at trial entry. – TAM Use –Dose –Duration –Median Follow-Up –Prophylaxis – 20 mg/d – 5 y – 5 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Yes, charts reviewed for prescription of CYP2D6 inhibitors, incorporated into phenotype CYP2D6 (*1, *2, *3, *4, *5, *6, *10, *17, *41) Blood samples Comparison, n Results PM: 2 null alleles (V/V, *3, *4, *5, or *6) or 1 null allele + 1 reduced function allele (*10, *17, *41) Phenotype PM IM – wt/v IM – v/v IM – wt/V IM: homozygous for reduced function allele (v/v) or heterozygous for reduced/ null function alleles or for wt/ null alleles + no inhibitor or wt/wt + weak inhibitor EM: wt/wt + no inhibitor IM – V/v EM n 48 132 12 OR (95% CI) for Breast Cancer Incidence 0.9 (0.5 to 1.7) 1.0 (0.7 to 1.5) 1.1 (0.3 to 3.9) 292 52 372 0.9 (0.7 to 1.3) 1.5 (0.8 to 2.7) 1 Reference CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.55 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited. Study n Sestak et al. (2012) 265 Study Design, Patients Case-control study of healthy, tamoxifen-treated women in the International Breast Cancer Intervention-I Study (IBIS-I) who were age 35–70 y with ≥2-fold relative risk of breast cancer – TAM Use –Dose –Duration –Median Follow-Up –Prophylaxis – 20 mg/d – 5 y – 8 y Study Accounted for CYP2D6 Inhibitors? Gene (Typed Variants)/ Sample Yes, 25 women (12%; 5 cases and 20 controls) who had an extensive metabolizer phenotype used a strong CYP2D6 inhibitor either at entry or during follow-up. Results were unchanged when these women were excluded. CYP2D6 (33 alleles by AmpliChipc CYP2D6 array) Whole blood samples Comparison, n Results PM = 2 null alleles PhenotypeCases (n=54)a PM 4 (7) IM 5 (9) PM+IM 9 (16) EM 45 (83) IM ≥ 1 reduced function allele but no wt allele EM ≥ 1 wt allele Controls (n=211)a 14 (7) 24 (11) ORb (95% CI) 38 (18) 173 (82) 1.1 (0.5 to 2.3) Reference 1.0 (0.3 to 3.3) 0.8 (0.3 to 2.2) Values are n (%). OR for incidence of estrogen receptor positive invasive breast cancer. a b Abbreviations: TAM, tamoxifen; chemo, chemotherapy; AI, aromatase inhibitor; V, variant; wt, wild type (*1 or *2); EM, extensive metabolizer; IM, intermediate metabolizer; PM, poor metabolizer; HR, hazard ratio; OR, odds ratio; TTR, time to recurrence; RFS, recurrence-free survival; OS, overall survival; DSS, disease-specific survival; NS, not significant; SSRI, selective serotonin reuptake inhibitor; NCCTG, North Central Cancer Treatment Group; LN, lymph node; PVI, peritumoral vascular invasion; RCT, randomized controlled trial; ER, estrogen receptor; PR, progesterone receptor; Ki-67, Ki-67 labeling index. c AmpliChip detects CYP2D6 alleles *1 to *10AB, *11, *14A, *14b, *15, *17, *19, *20, *25, *26, *29 to *31, *35, *36, *40, *41, *1xN, *2xN *4xN, *10xN, *17xN, *35xN, and *41xN. Technology Evaluation Center 56 Table B. Association of Genotype With Clinical Outcome in Predominantly White Populations (cont’d) CYP2D6 Pharmacogenomics of Tamoxifen Treatment ©2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.57 Technology Evaluation Center Technology Evaluation Center Blue Cross and Blue Shield Association 225 North Michigan Avenue Chicago, Illinois 60601-7680 www.bcbs.com/tec ® Registered marks of the Blue Cross and Blue Shield Association, an Association of Independent Blue Cross and Blue Shield Plans ®’Registered trademark of Kaiser Permanente © 2014 Blue Cross and Blue Shield Association. Reproduction without prior authorization is prohibited.