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Lung Cancer 69 (2010) 1–12 Contents lists available at ScienceDirect Lung Cancer journal homepage: www.elsevier.com/locate/lungcan Review New strategies to overcome limitations of reversible EGFR tyrosine kinase inhibitor therapy in non-small cell lung cancer Robert C. Doebele ∗ , Ana B. Oton, Nir Peled, D. Ross Camidge, Paul A. Bunn Jr. University of Colorado Cancer Center, Division of Medical Oncology, Aurora, CO, United States a r t i c l e i n f o Article history: Received 9 September 2009 Received in revised form 10 December 2009 Accepted 11 December 2009 Keywords: NSCLC EGFR HER T790M Irreversible TKI Antibody a b s t r a c t The epidermal growth factor receptor (EGFR), a member of the HER family of receptors, has become a well-established target for the treatment of patients with non-small cell lung cancer (NSCLC). Several EGFR-targeted agents produce objective responses in a minority of unselected patients, but a majority of those with EGFR-activating mutations; however, all responders eventually develop resistance. The modest activity of agents that target only EGFR may be due, in part, to the complexity and interdependency of HER family signaling. The interdependent signaling that occurs between EGFR and HER2 provides a rationale for the simultaneous inhibition of these receptors with reversible and irreversible inhibitors. Several agents with activity against both EGFR and HER2 are currently under development. Irreversible EGFR/HER2 tyrosine kinase inhibitors (TKIs) (e.g., BIBW 2992, HKI-272) and pan-HER TKIs (e.g., PF00299804) comprise a novel class of agents in clinical development that may prevent and overcome inherent and acquired resistance to first-generation reversible EGFR TKIs. Other agents in development include the monoclonal antibody pertuzumab, and XL-647, which inhibits EGFR and HER2, as well as multiple vascular endothelial growth factor receptor family members. Here we briefly review the currently available EGFR-targeted agents, discuss the rationale for extending inhibition to other HER family members, weigh the merits of irreversible HER family inhibition, and summarize preclinical and clinical data with EGFR/HER2 and pan-HER inhibitors under clinical development. © 2009 Elsevier Ireland Ltd. All rights reserved. 1. Introduction Lung cancer is the leading cause of cancer death in the United States and worldwide, claiming the lives of approximately 162,000 Americans and 1.4 million people around the world in 2008 [1–3]. Lung cancer is divided into 4 histologic subtypes according to the World Health Organization (WHO) classification: adenocarcinoma, squamous carcinoma, large-cell carcinoma, and small-cell carcinoma. Because the first 3 have similar treatment and staging paradigms, they are frequently grouped together as non-small cell lung cancer (NSCLC). The NSCLC histologies represent approximately 85% of all lung cancers [4]. Most patients with NSCLC are diagnosed with advanced-stage disease (stages IIIB and IV) requiring systemic therapy [5]. Unfortunately, the prognosis for such patients is poor, with 5-year survival rates of 8% and 2% associated with stages IIIB and IV disease, respectively [6]. Median overall survival (OS) ranges from approximately 7.4 to 12.3 months with first-line chemotherapy [7–15], and from 6.7 to 8.4 months with salvage therapy [16–20]. The epidermal growth factor receptor (EGFR) mediates several cell functions, including proliferation, migration, and survival [21]. Its dysregulation triggers different mechanisms that contribute to the development of lung cancer. EGFR is overexpressed in several malignancies, occurring in 40–80% of NSCLCs, which has made it the focus of many new treatment strategies [22]. The currently available EGFR-targeted agents have provided benefit to certain subpopulations of patients with NSCLC. However, the efficacy of these agents in the general population has been modest and limited by resistance in patients who initially respond. Several compounds that simultaneously target EGFR and other members of the HER/ErbB family are currently in clinical development for NSCLC and may have the potential for overcoming the limitations of reversible inhibitors that solely target EGFR. Here we briefly review the currently available EGFR-targeted agents, discuss the rationale for the irreversible inhibition of EGFR and other HER family members, and summarize preclinical and clinical data with EGFR/HER2 and pan-HER inhibitors that are currently in clinical development for the treatment of patients with NSCLC. 2. HER family ∗ Corresponding author at: RC1-South Tower, Mail Stop 8117, 12801 E. 17th Ave., Aurora, CO 80045-0511, United States. Tel.: +1 3037242980; fax: +1 3037243889. E-mail address: [email protected] (R.C. Doebele). 0169-5002/$ – see front matter © 2009 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.lungcan.2009.12.009 The EGFR, also known as HER1 and ErbB1, was the first described for a family of receptor tyrosine kinases (TKs) that also includes 2 R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 Fig. 1. EGFR and downstream signaling. (A) Schematic representation of the structure of EGFR. The locations and regions of commonly occurring mutations in the EGFR TK domain are shown in the exon boundary map. (B) Ligand-bound receptors form functionally active homodimers or heterodimers, resulting in the activation of downstream signaling pathways that promote cellular proliferation and survival. No known ligand exists for HER2, and HER3 has no functional TK activity. Other receptor TKs (e.g., IGF-1R, MET) can modulate EGFR downstream pathways. Note: EGFR, epidermal growth factor receptor; HB-EGF, heparin-binding epidermal growth factor; IGF-1R, insulin-like growth factor receptor-1; NRG, neuregulin; RTK, receptor tyrosine kinase; TK, tyrosine kinase. (Panel A adapted from Kumar et al. [23]; panel B adapted from Ciardiello and Tortora [26].) HER2/neu (ErbB2), HER3 (ErbB3), and HER4 (ErbB4). EGFR is a 170kDa transmembrane protein that is widely expressed in several malignancies (e.g., lung, breast, colon, esophageal). The HER (ErbB) family of receptors share important structural similarities across 4 extracellular domains (I through IV), a transmembrane domain, and intracellular domains consisting of a kinase domain and tyrosine phosphorylation sites in the carboxy-terminal tail (Fig. 1A) [23]. However, HER2 lacks a ligand-binding domain and HER3 is devoid of functional kinase activity [24,25]. Multiple ligands bind to this family of receptors with varying specificity (Fig. 1B) [26]. Ligand binding induces HER receptor homodimerization (e.g., EGFR–EGFR) or heterodimerization (e.g., R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 EGFR–HER2) [21]. HER2 has no known ligand, but is the preferred binding partner of EGFR and the other HER family members [27]. EGFR containing activating mutations in the kinase domain (exons 18–21) were initially identified in patients with significant responses to gefitinib [28,29]. EGFR harboring deletions in exon 19 (del19), substitution mutations in exon 21 (L858R), or less common mutations (e.g., G719S, L861Q) enables constitutive activation of the kinase function in the absence of ligand stimulation by causing a shift in the equilibrium between active and inactive states of the kinase domain to favor the active state (Fig. 1A) [23,30]. These activating mutations confer hypersensitivity to TK inhibitors (TKIs), but not inhibition by monoclonal antibodies, because the mutations decrease the affinity of the EGFR for adenosine triphosphate (ATP), thus improving competitive binding by the inhibitors [31]. Receptor dimerization is a required step in HER family signal transduction. This results in the transphosphorylation of specific tyrosine residues within the intracellular domain and leads to the activation of downstream signaling events that modulate cellular processes, such as those involved in cellular proliferation and survival (Fig. 1B) [26]. The type and duration of cellular response to HER family signaling is dependent on the specific HER dimer formed. For example, heterodimeric receptor pairs have a greater mitogenic and transforming effect than the corresponding homodimers [32–34]. 3. Blocking EGFR in NSCLC Given the important role of EGFR in NSCLC, several EGFRtargeted agents have been developed, including small-molecule TKIs that bind with the intracellular TK domain (e.g., erlotinib, gefitinib) and monoclonal antibodies directed to the extracellular receptor domain (e.g., cetuximab). 4. Reversible EGFR TKIs (gefitinib and erlotinib) Gefitinib and erlotinib are orally administered reversible EGFR TKIs. Gefitinib (Iressa® ; Table 1) was the first EGFR-targeted agent approved by the US Food and Drug Administration (FDA) for the second- and third-line treatment of patients with NSCLC [35]. The initial approval was based largely on the data from the phase I/II IDEAL 1 and IDEAL 2 studies [36,37]. However, gefitinib failed to show an OS benefit in a confirmatory phase III trial (ISEL) designed to evaluate gefitinib against placebo [38], which prompted a change in the US label restricting gefitinib use to patients with NSCLC who currently or who had previously derived benefit from treatment. More recently, gefitinib showed noninferiority in OS and more favorable tolerability compared with docetaxel in the phase III INTEREST trial of patients with previously treated NSCLC [39]. Erlotinib (Tarceva® ; Table 1) is currently the only EGFR inhibitor approved by the FDA for the treatment of patients with NSCLC [40]. This agent has shown survival benefit in previously treated patients with NSCLC. In the BR.21 trial, 731 patients were randomized in a 2:1 ratio to receive erlotinib 150 mg/day or placebo [16]. Improved OS was observed with erlotinib (7.9 months vs. 3.7 months; hazard ratio [HR], 0.7; p < 0.001). In the phase III SATURN trial, erlotinib was shown to produce prolonged progression-free survival (PFS) (HR, 0.71) and OS (HR, 0.81) when compared with placebo in the maintenance (immediate second-line therapy) setting after firstline chemotherapy [41]. The improvements were most striking in patients with EGFR-activating mutations. While it is clear that EGFR TKIs can provide clinical benefits to patients with NSCLC, early clinical studies showed that only ∼10% of unselected patients respond to EGFR TKIs (Table 2) [16,17,36–39,42–50]. Retrospective analyses from phase II studies of EGFR TKIs identified certain clinical characteristics associated 3 with objective responses to treatment, including Asian ethnicity, female gender, adenocarcinoma histology, and never-smoking history [17,36,37,51,52]. However, the predictive value of these demographic and clinical markers is not consistently reliable [16,38]. Several molecular biomarkers have also been identified that may be more effective predictors of response to EGFR TKI therapy. The most effective marker appears to be the presence of somatic gain-of-function (activating) mutations in the kinase domain of EGFR (Fig. 1A) [23]. Activating mutations are present in ∼10% of American and European patients and 25–50% of Asian patients with NSCLC [53]. Activating EGFR mutations are more frequently associated with a never-smoking history, adenocarcinoma histology, and bronchoalveolar features [42]. About 90% of EGFR-activating mutations are clustered in exons 19 and 21 [42]. Patients with del19 mutations demonstrate a higher response rate and longer survival with EGFR TKI therapy than patients with point mutations in exon 21 [43,54,55]. Response rates among patients with activating mutations are approximately 20–90%, compared with 10–20% in unselected patients (Tables 2 and 3) [16,17,36–38,43–47,49,50,56–66]. Results from a subanalysis of 437 never-smoking Asian patients from the IPASS trial, which compared first-line gefitinib with chemotherapy, showed that PFS was significantly longer following the administration of gefitinib to patients with EGFR mutations (HR, 0.48; p < 0.0001). Conversely, in patients with wild-type EGFR, PFS was longer following chemotherapy (HR, 2.85; p < 0.0001) [63]. These data were confirmed in other randomized trials [67,68] and in large phase II trials [69,70]. Other potential biomarkers of responsiveness include increased EGFR gene copy number as detected by fluorescence in situ hybridization (FISH). True gene amplification or high polysomy is defined when gene clusters are recognized and/or more than 4 EGFR gene copies exist in >40% of cells [71]. Our in vitro experience in NSCLC cell lines showed that both EGFR gene amplification and high copy number were significantly associated with sensitivity to EGFR TKIs [72]. Indeed, in both the BR.21 and ISEL trials, FISHpositive patients treated with EGFR TKIs demonstrated improved OS compared with patients receiving placebo [73,74]. EGFR protein expression by immunohistochemistry (IHC) has a lesser degree of predictive power [73–78]. In the BR.21 trial, IHC-positive patients treated with erlotinib had significantly superior survival compared with placebo-treated patients, whereas the ISEL trial showed that gefitinib was associated with improved survival in IHC-positive patients; however, the difference was not statistically significant [73,77]. Combining FISH and IHC may also predict EGFR TKI benefit [78]. Mutations in the KRAS gene, which are present in approximately 15–30% of NSCLC cases, are strongly associated with lack of response to EGFR TKIs [74,79–81]. In contrast to colorectal cancer, where KRAS mutation status predicts benefit from EGFR monoclonal antibody therapy, most studies in NSCLC show no significant association between the presence or absence of KRAS mutations and PFS or OS after EGFR TKI or monoclonal antibody therapy. This includes the recent SATURN trial, in which patients received immediate second-line therapy with erlotinib or placebo [41]. Interestingly, KRAS mutations and EGFR-activating mutations are almost always mutually exclusive, suggesting that they play functionally overlapping roles in NSCLC tumorigenesis [74,79,80]. Despite the clinical benefits achieved with EGFR TKIs in selected patient populations, acquired resistance has proven to be a major clinical issue. Nearly all patients who initially respond to EGFR TKI treatment eventually relapse. Several underlying molecular mechanisms have been implicated in resistance to EGFR TKIs. The most common form of resistance involves the missense mutation T790M within the EGFR TK domain (Figs. 1A and 2) [23,82,83]. This mutation is associated with >50% of cases of acquired resistance [84]. 4 R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 Table 1 EGFR, pan-HER, and EGFR/HER2 inhibitors in NSCLC. Agents Targets (IC50 , nM) Phase of clinical development First-generation reversible TKIs Gefitinib Erlotinib EGFR (33), HER2 (>3500) EGFR (0.56), HER2 (512), HER4 (790) Restricted access in United States FDA approved Irreversible TKIs BIBW 2992 HKI-272 PF00299804 EGFR (0.5), HER2 (14) EGFR (92), HER2 (59) EGFR (6.0), HER2 (45.7), HER4 (73.7) III II II Other reversible TKIs Lapatinib XL-647 EGFR (10.8), HER2 (9.2) EGFR (0.3), HER2 (16), VEGFR-2 (1.5), VEGFR-3 (8.7), EphB4 (1.4) II II Monoclonal antibodies Cetuximab Pertuzumab EGFR (NA) HER2 (NA) III II Note: EGFR, epidermal growth factor receptor; FDA, US Food and Drug Administration; IC50 , maximal inhibitory concentration; NA, not applicable; NSCLC, non-small cell lung cancer; TKI, tyrosine kinase inhibitor. The IC50 values shown are from cell-free in vitro kinase assays of gefitinib [64], erlotinib [40], BIBW 2992 [124], HKI-272 [35], PF-299804 [40], lapatinib [126], and XL-647 [125] against wild-type HER receptors. All values are expressed in nM. Table 2 Clinical trials evaluating the EGFR TKIs gefitinib and erlotinib in unselected patients as first-, second-, or third-line therapy in NSCLC. EGFR TKI Trials Line of therapy Na Second, third 2618 (2339 response evaluable) 3.1–22.5 5.6–11.5 Gefitinib IDEAL 1 [36] IDEAL 2 [37] ISEL [38] INTEREST [39] INVITE [45] V-15-32 [44] Second, third 880 (819 response evaluable) 8.9–28.3 6.7–14.7 Erlotinib BR.21 [16] Perez-Soler et al. [17] Perng et al.b [46] Kubota et al. [47] Giaccone et al. [50] SWOG 0341 [48] Jackman et al. [43] Lilenbaum et al. [49] First 261 4.0–22.7 5–13 ORR, % Median OS, mo Note: EGFR TKI, epidermal growth factor receptor tyrosine kinase inhibitor; MS, median survival; NSCLC, non-small cell lung cancer; ORR, objective response rate; OS, overall survival; PFS, progression-free survival; SWOG, Southwest Oncology Group. a Sum total number of patients treated with EGFR TKIs in all studies listed in each row (IDEAL-1 [n = 208] [36], IDEAL-2 [n = 216] [37], ISEL [n = 1129, of whom 959 were evaluable for response] [38], INTEREST [n = 659, of whom 723 were evaluable for response] [39], INVITE [n = 97] [45], V-15-32 [n = 245, of whom 200 were evaluable for response] [44], BR.21 [n = 488, of whom 427 for evaluable for response] [16], Perez-Soler et al. [n = 57] [17], Perng et al. [n = 273] [46], Kubota et al. [n = 62] [47], Giaccone et al. [n = 53] [50], SWOG 0341 [n = 76] [48], Jackman et al. [n = 80] [43], Lilenbaum et al. [n = 52] [49]). b Median OS not evaluated in Perng et al. [46]. Table 3 Clinical trials evaluating the EGFR TKIs gefitinib and erlotinib in selected patients as first-line therapy in NSCLC. EGFR TKI Trials Gefitinib WJTOG 0403b [59] SWOG 0126c [65] Sugio et al.b [58] Sequist et al.b [57] ONCOBELLd [61] IPASSe [63] Inoue [66] Erlotinib Paz-Ares et al.b , f [56] Jackman et al.b , g [43] Na ORR, % Median OS, mo 864 17–75 13–20 53 65–90 30f Note: BAC, bronchioloalveolar carcinoma; EGFR TKI, epidermal growth factor receptor tyrosine kinase inhibitor; ORR, objective response rate; OS, overall survival; SWOG, Southwest Oncology Group. a Sum total number of patients treated with EGFR TKIs in all studies listed in each row (WJTOG 0403 n = 28) [59], SWOG 0126 [n = 135] [65], Sugio et al. [n = 19] [58], Sequist et al. [n = 31] [57], ONCOBELL [n = 42] [61], IPASS [n = 609] [63], Paz-Ares et al. [n = 21] [56], Jackman et al. [n = 32] [43]). b Somatic mutation-positive selected patients. c Selected by histology (BAC). d Selected by tobacco history (never smokers) or increased EGFR gene copy number or activation of antiapoptotic protein Akt. e Selected by smoking history. f Overall survival not reported in Paz-Ares et al. g Erlotinib and gefitinib. R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 Fig. 2. Molecular surface model of the catalytic cleft of T790M-mutated EGFR in the active conformation. T790M-mediated resistance has been attributed to steric hindrance due to the bulky methionine side chain (red spheres) [23,82]; however, it more likely occurs through an increased binding affinity for ATP [83]. Irreversible inhibitors may overcome T790M-mediated resistance by covalently binding to cysteine-797 (shown in yellow). The blue mesh represents erlotinib bound within the catalytic cleft. Note: ATP, adenosine triphosphate; EGFR, epidermal growth factor receptor. (Adapted from Kumar et al. [23].) Consistent with this mutation emerging through selective pressure during EGFR TKI treatment, a recent study using a highly sensitive mutation-specific assay showed that low levels of T790M could be detected in tumor samples from TKI-naïve patients [85]. Although EGFR TKI treatment did induce response in these patients, PFS was significantly shorter than in patients who did not harbor T790M at baseline (7.7 months vs. 16.5 months; p < 0.001). These results suggest that treatment with reversible EGFR TKIs may select for pre-existing T790M clones in certain patients, resulting in relapse. Therefore, this mutation may be a useful pretreatment biomarker to identify patients who are likely to derive shorter periods of benefit from erlotinib or gefitinib. Several other resistance-conferring EGFR mutations have also been identified [42,86]. Additionally, mechanisms of acquired resistance unrelated to EGFR have also been identified. Amplification of the MET oncogene [87] and increased expression of insulin-like growth factor-1 receptor (IGF-1R) [88] can circumvent EGFR inhibition through the activation of downstream signaling pathways (Fig. 1B) [26]. Early identification of patients at risk for relapse through the detection of biomarkers associated with acquired resistance to EGFR TKIs (e.g., T790M, MET amplification) could help guide future treatment choices beyond the second line. 5. Anti-EGFR monoclonal antibodies (cetuximab) Cetuximab (Erbitux® ; Table 1) is a humanized monoclonal antibody that binds the extracellular portion of the EGFR, inducing its internalization and blocking its downstream cellular signaling [89]. While single-agent cetuximab has minimal activity (6.9% objective response rate [ORR]) in pretreated patients with NSCLC [90], recent results from several phase II trials [62,91–94] and the phase III FLEX trial suggest that this agent may increase the effectiveness of first-line chemotherapy [7]. In the largest of these studies, cetuximab provided an OS benefit when added to cisplatin/vinorelbine chemotherapy compared with chemotherapy alone (11.3 months vs. 10.1 months; HR, 0.87; p < 0.044) [7]. In another randomized phase III trial (BMS-099) designed to evaluate first-line carboplatin/taxane chemotherapy with or without cetux- 5 imab in unselected patients, cetuximab failed to meet the primary end point of PFS (4.40 months vs. 4.24 months; HR, 0.9; p = 0.23) by an independent review committee; however, when assessed by clinical investigators as a secondary end point, PFS was significantly prolonged by the addition of cetuximab (4.4 months vs. 3.8 months; HR, 0.79; p = 0.0036), and ORRs were also improved [95]. Cetuximab has not yet received approval from the FDA for the treatment of patients with NSCLC. However, the National Comprehensive Cancer Network now recommends cetuximab in combination with cisplatin/vinorelbine as a treatment option for patients with advanced or recurrent NSCLC who meet certain eligibility criteria (including EGFR expression as detected by IHC [≥1 positive tumor cell]) [96]. As compared with EGFR TKIs, fewer predictive biomarkers have been identified for cetuximab benefit in NSCLC. In metastatic colorectal cancer (mCRC), EGFR protein expression was required for enrollment in the landmark trial, and the presence of KRAS mutations predicted nonresponsiveness to cetuximab [97,98]. In lung cancer, however, the KRAS mutation status was not a useful biomarker for cetuximab benefit in either the FLEX or BMS-099 trial [99–101]. Analysis of EGFR FISH in FLEX and BMS-099 also failed to show any prediction for benefit [99,100]. However, analysis of tumor samples from patients receiving concurrent or sequential cetuximab in combination with chemotherapy revealed markedly improved survival for patients who were FISH positive for EGFR (OS, 15 months vs. 7 months for FISH-negative patients; HR, 0.83; p = 0.065) [102]. Previous data demonstrated that FISH positivity is not a positive prognostic factor in NSCLC [103,104]. These results provide a premise for further assessment of the predictive value of FISH, which will be tested in the Southwest Oncology Group (SWOG) 0817 trial, a first-line study randomizing patients to chemotherapy with or without cetuximab. Retrospective analyses of large randomized trials such as FLEX as well as prospective clinical studies will be required to validate KRAS mutations, EGFR protein expression, and other molecular characteristics as predictive biomarkers for cetuximab in NSCLC. 6. Rationale for EGFR/HER2 inhibition Although EGFR is clearly a valid target in NSCLC, the efficacy demonstrated by EGFR-targeted agents is not as impressive as was initially expected. However, the modest activity of agents that solely block EGFR is not surprising given the complex nature and interdependency of HER family signaling. One approach to improve responsiveness to EGFR inhibitors may be to simultaneously target multiple HER family members. As highlighted above, HER2 is the preferred partner for all of the HER family members, including EGFR [27]. The molecular interactions that occur between EGFR and HER2 regulate and diversify EGFR downstream signaling, and EGFR mitotic signals can be augmented by the coexpression of HER2 [33]. For example, HER2 amplification in human mammary epithelial cell lines was found to cause constitutive activation of HER2 and ligand-independent activation of EGFR [105]. In preclinical studies, both EGFR and HER2 have demonstrated the potential to facilitate transformation to a malignant phenotype independently [106] and synergistically [32]. Indeed, high synchronous coexpression of EGFR and HER2 is associated with an unfavorable prognosis in patients with stage I through IIIA NSCLC [107–109]. Such synchronous overexpression may increase the formation of EGFR/HER2 heterodimers, resulting in a more aggressive phenotype. Such a cooperative role for these receptors was supported in a recent preclinical study that showed that in NSCLC cell lines that coexpress EGFR and HER2, knockdown of HER2 6 R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 expression via RNA interference resulted in growth inhibition in both cell culture and tumor xenograft models [110]. Interestingly, Cappuzzo et al. showed that HER2 amplification in patients with NSCLC, particularly in conjunction with EGFR mutations or amplification/overexpression, correlates with sensitivity to EGFR TKIs [111]. HER2 amplification has been detected in patients with lung adenocarcinoma at a frequency of ∼10%, and overexpression of the HER2 protein is found in a subset of NSCLCs (20–30%), mostly adenocarcinomas [111–113]. Overexpression of HER2 has been proven to be an independent unfavorable prognostic factor in resected NSCLC [112]. Somatic mutations of HER2 have also been identified in a small, but potentially important fraction of patients with lung adenocarcinoma (<5%). As with activating mutations of EGFR, the presence of HER2 mutations correlates with female gender, nonsmoking status, and Asian background in patients with adenocarcinomas [114]. Such mutations may act to circumvent EGFR-mediated signaling in NSCLC. In a preclinical study, transfection of bronchial epithelial cells with the G776(YVMA) HER2 kinase domain mutation resulted in enhanced transformation compared with cells containing wild-type HER2 [115]. HER2 YVMA was capable of transactivating EGFR both in the absence of ligand and in the absence of EGFR kinase activity. It was also found that lung cancer cell lines harboring a G776 HER2 mutation were resistant to erlotinib/gefitinib treatment but remained sensitive to inhibition of both EGFR and HER2. In addition, there are limited preclinical and clinical data suggesting that tumors with HER2 mutations may respond to trastuzumab therapy [115,116]. Currently, a phase II trial evaluating the efficacy of trastuzumab in patients with HER2 FISH-positive/and or HER2 mutation-positive NSCLC is recruiting patients. 7. EGFR/HER2 inhibition in NSCLC The role of HER2 in NSCLC and the interdependent signaling that occurs between this receptor and the other HER family members provide a rationale for the simultaneous inhibition of EGFR and HER2 in the treatment of NSCLC. While inhibition of EGFR blocks only EGFR-mediated signal transduction, inhibition of EGFR and HER2 may more effectively disrupt signaling from EGFR/HER2 heterodimers. Furthermore, activity against both EGFR and HER2 would be expected to interfere with signaling from all NSCLCrelated homodimers and heterodimers (Fig. 3). Indeed, preclinical studies in a variety of malignant cell types, including NSCLC, have shown that EGFR/HER2 inhibition can induce superior anti-tumor activity compared with single-receptor targeting [112,117–123]. Several agents with activity against both EGFR and HER2 are currently in clinical development for NSCLC (Table 1) [35,40,124,125]. 8. Reversible EGFR/HER2 TKIs 8.1. Lapatinib Lapatinib (GW572016; Tykerb® ) is an oral, reversible, TKI that targets EGFR and HER2 (Table 1) [126]. This agent was approved by the FDA in combination with capecitabine in the treatment of patients with advanced or metastatic breast cancer with HER2 overexpression. The use of this agent in breast cancer validates EGFR/HER2 inhibition as an effective treatment approach. However, clinical results with this agent in NSCLC have been disappointing. A phase II trial of lapatinib in patients with advanced NSCLC who had either bronchoalveolar carcinoma (BAC) histology or nonsmoking history was stopped early after failing to meet the primary end point of response [127]. Based on the results of this study, lapatinib is no longer in clinical development as monother- apy for the treatment of patients with NSCLC. In weighing the potential benefits of additional HER2 blockade, it is important to note that the potency of lapatinib against HER2 appears to be similar to that of the irreversible inhibitors discussed below (Table 1) [126]. 9. Irreversible HER family TKIs A newer class of small-molecule HER family inhibitors, the irreversible TKIs, has emerged in recent years (Table 1) [35,40,124]. Most of these agents are active against EGFR and HER2, and some also inhibit HER4. Unlike reversible TKIs (e.g., erlotinib, gefitinib, lapatinib), these agents bind covalently to the kinase domain of their target receptors. Importantly, many of these irreversible inhibitors have demonstrated activity in preclinical studies against EGFR mutations that confer resistance to the reversible EGFR TKIs gefitinib and erlotinib (e.g., T790M; Fig. 2) [23,82,83]. Additionally, preclinical studies have shown that resistance develops less frequently with this class of agents compared with reversible inhibitors [128]. Thus, these agents should be studied both in combination with erlotinib or gefitinib to delay the development of resistance and prolong PFS and after progression following erlotinib or gefinitib. 9.1. BIBW 2992 BIBW 2992 is a irreversible EGFR/HER2 inhibitor, with activity against wild-type and mutant forms of EGFR, including T790M [124]. In preclinical cell-based assays, BIBW 2992 was more potent than gefitinib, erlotinib, and lapatinib in inducing the cell death of NSCLC cell lines, including those harboring wild-type EGFR, the activating L858R mutation, and the erlotinib-resistant T790M mutation [124]. Importantly, the half maximal inhibitory concentrations (IC50 s) for BIBW 2992 in these in vitro models were typically substantially less than the maximum achievable drug plasma concentration (300 nM) [129]. BIBW 2992 also demonstrated activity in cells expressing the EGFR resistance mutations D770-771insNPG and the variant III deletion (EGFRvIII). Furthermore, BIBW 2992 effectively blocked the growth of NSCLC cell lines (NCI-H1781) expressing a HER2 activating mutation (776insV). Recently, Bean et al. showed that BIBW 2992 is active against a novel secondary mutation, T854A, which is associated with acquired resistance to reversible EGFR TKIs [130]. In both human NSCLC tumor xenograft models and murine lung cancer models BIBW 2992 was effective in tumors harboring the L858R/T790M double mutant. Phase I studies of single-agent BIBW 2992 show that it exhibits side effects characteristic of the reversible EGFR TKIs, including cutaneous rash and gastrointestinal disturbances [131–134]. BIBW 2992 had a manageable toxicity profile when administered in a continuous daily dosing regimen [131,134]. In one phase I study, 3 of 12 patients with NSCLC had confirmed partial responses (PRs), 2 of whom had del19 mutations. The recommended phase II dose of 50 mg once daily was well tolerated [134]. BIBW 2992 is being evaluated in the single-arm phase II LUX-Lung 2 trial of patients with advanced lung adenocarcinoma harboring activating EGFR mutations who are chemotherapy naïve (including patients who had received neoadjuvant/adjuvant chemotherapy) or who had experienced failure of first-line chemotherapy [135,136]. The initial starting dose of 50 mg/day was reduced to 40 mg/day secondary to toxicities, and patients received treatment until disease progression. Interim results from secondline patients treated in this study were recently presented at the 2009 Annual Meeting of the American Society of Clinical Oncology [135]. Most patients in the second-line setting received a starting R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 7 Fig. 3. Differential activity of sole EGFR inhibition vs. EGFR/HER2 inhibition. EGFR inhibition interferes only with EGFR-mediated signal transduction. EGFR/HER2 inhibition blocks signal transduction from all NSCLC-related receptor pairs. It is not known whether blocking multiple HER family members will result in improved clinical efficacy in NSCLC. Note: EGFR, epidermal growth factor receptor; NSCLC, non-small cell lung cancer. dose of 50 mg/day. A total of 67 patients who had received BIBW 2992 as second-line treatment were evaluable for response. With a median follow-up of 6.6 months, the ORR (complete response [CR] plus PR) was 64% (43 of 67 patients) and the disease control rate (CR plus PR plus stable disease [SD]) was 96% (64 of 67 patients). PFS among patients receiving second-line BIBW 2992 was 10.2 months. No patients with the T790M resistance mutation have yet been evaluated. Interim results from the first 53 chemotherapynaïve patients treated in this study were presented at the 2009 World Conference on Lung Cancer [136]. Thirty patients received a starting dose of 50 mg/day and 23 received 40 mg/day. At 3.3 months of follow-up, the response rate was 63% among the 38 evaluable patients; 13 patients (34%) had SD. The most frequently occurring side effects included skin toxicity (grade 3: first-line, 5.7%; second-line, 17.8%) and diarrhea (grade 3: first-line, 18.9%; second-line, 16.4%) [135,136]. A randomized, double-blind, multicenter phase IIB/III trial (LUX-Lung 1) is currently in progress to evaluate BIBW 2992 against placebo in patients with NSCLC who experienced failure of prior erlotinib or gefitinib [137]. The phase III LUX-Lung 3 trial also began accrual to compare BIBW 2992 with cisplatin/pemetrexed in first-line patients with EGFR mutationpositive NSCLC. transformed with the A775insYVMA mutation were found to be sensitive to HKI-272 [143]. In vivo, treatment with HKI-272 resulted in substantial anti-tumor effects in HER2- and EGFR-dependent human tumor xenograft models [144]. HKI-272 was evaluated in a phase I trial of patients with advanced EGFR/HER2 expressing solid tumors by IHC [139]. The most common and dose-limiting adverse event (AE) was diarrhea. Other common AEs were nausea, vomiting, fatigue, and anorexia. No radiographic responses or PRs were achieved among the 14 patients with NSCLC enrolled in the study. However, SD for >24 weeks was observed in 6 patients with NSCLC who had previously experienced gefitinib or erlotinib failure. HKI-272 was evaluated in a phase II clinical trial of patients with advanced NSCLC who had previously received up to 3 chemotherapy regimens [145]. Patients were divided into 3 groups: patients who experienced failure of gefitinib or erlotinib and had EGFR mutations (arm A; n = 91), patients who were mutation negative (arm B; n = 48), and patients who did not receive prior EGFR TKIs (arm C; n = 28). There were no significant differences among arms A, B, and C in response rate (2%, 2%, and 4%, respectively), SD rate (47%, 46%, and 39%, respectively), or median PFS (11.6, 14.7, and 7.4 weeks, respectively). Currently, there are no other ongoing studies of HKI-272 in patients with NSCLC. 9.2. HKI-272 HKI-272 (neratinib) is an irreversible inhibitor of EGFR and HER2. In preclinical studies, HKI-272 was more potent than gefitinib in suppressing ligand-induced EGFR autophosphorylation and downstream signaling and growth-inhibiting NCI-H1975 BAC cells harboring L858R and T790M mutations in EGFR [128,138]. However, a recent study in NSCLC cell culture models showed that T790M-mediated resistance emerges in the presence of HKI-272 at 0.2 M (111 ng/mL), similar to the maximum concentration (Cmax ) (112 ng/mL) observed in the phase I trial [139], indicating that this agent could overcome T790M only at concentrations above those achieved in clinical trials [140]. HKI-272 also showed activity in a gefitinib-resistant BAC cell line (NCI-H1650) harboring an in-frame deletion mutation of EGFR (delE746-A750) [128], and in Ba/F3 cells transformed with the EGFRvIII mutant, which is resistant to gefitinib and erlotinib [141]. This agent has also demonstrated activity in cells harboring various HER2 mutants. NCI-H1781 cells harboring the 776insV mutation [142] and erlotinib-resistant murine cells 9.2.1. PF00299804 PF00299804 is an orally bioavailable, irreversible pan-HER TKI. Pan-HER inhibitors are active against EGFR, HER2, and HER4. PF00299804 effectively inhibited the in vitro kinase activity of wildtype EGFR with a potency similar to that of gefitinib, erlotinib, and another irreversible pan-HER inhibitor, CI-1033 [40]. In preclinical cell culture models, PF00299804 demonstrated activity in cells containing common EGFR mutations and the EGFR L858R/T790M double mutant at significantly lower IC50 values than gefitinib. In addition, PF00299804 was active in NSCLC cell lines harboring the HER2 776insV mutation and in YVMA-expressing cells. In vivo, PF00299804 demonstrated anti-tumor activity in xenograft models of T790M-mediated gefitinib resistance [40]. A phase I trial studying PF00299804, in which 42 patients with NSCLC were enrolled, showed acceptable tolerability, with the most frequently reported AEs being diarrhea (78%) and rash (65%) [146]. Among 29 patients evaluable for tumor response, 2 had a PR and 8 showed SD. Currently, none of the patients with biopsy-proven 8 R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 T790M mutations has shown response, although the number of patients with this mutation is small. A single patient with the T790M mutation detected in the blood had SD [146]. PF-00299804 is being evaluated in a 2-arm, phase II trial in patients with advanced NSCLC after failure of ≥1 prior chemotherapy regimen and prior treatment with erlotinib [147]. Patients with wild-type KRAS who had progressive disease after ≥1 prior chemotherapy regimen and erlotinib were enrolled by histology: adenocarcinoma (arm A) and non-adenocarcinoma (arm B). To date, 34 patients have enrolled (arm A, n = 30; arm B, n = 4). In a preliminary report of 20 patients evaluable for response, PRs (unconfirmed) were observed in 2 patients and 10 patients had SD (9 of 18 patients in arm A and 1 of 2 patients in arm B) with a median duration of 11.5 weeks. Additionally, disease control was reported in patients harboring T790M mutations. The most common AEs were skin and gastrointestinal disorders (grade 3 in 19% and 13% of patients, respectively); grade 4 pulmonary embolus/dyspnea was reported in 2 patients. 10. Other emerging agents 10.1. Pertuzumab Although trastuzumab has failed to show clinical activity in NSCLC [148,149], another HER2-directed monoclonal antibody, pertuzumab, is in clinical development for NSCLC. Pertuzumab is a recombinant, humanized monoclonal antibody and the first in a new class of agents known as the HER dimerization inhibitors. While this agent is specifically directed against HER2, it binds to a region of the extracellular domain that interferes with the heterodimerization of HER2 with other HER family members [150]. In vitro, this agent has been shown to block HER signaling, leading to apoptosis. Interestingly, in vivo studies suggest that the anti-tumor activity of pertuzumab is not restricted to HER2 overexpression, in contrast to trastuzumab [150]. A phase II trial was conducted to evaluate the activity of pertuzumab in patients with recurrent NSCLC [151]. Patients were treated with pertuzumab intravenously once every 3 weeks. The primary end point was ORR. Pertuzumab was well tolerated, but no responses were seen in the 43 patients treated. Secondary end points, such as pharmacodynamic activity as assessed by F18-fluorodeoxyglucose positron emission tomography, correlated with prolonged PFS in 27.3% of the patients. Currently, another phase II study is under way to evaluate the combination of pertuzumab with erlotinib for the second-line treatment of patients with advanced NSCLC. 10.2. ZD6474 (vandetanib, Zactima) ZD6474 (vandetanib, Zactima) is a dual inhibitor of the EGFR and vascular endothelial growth factor-2. Despite promising results in vitro and in vivo that this drug could retain efficacy in the presence of acquired EGFR TKI resistance, there is no clinical evidence that it exhibits any benefit beyond what current EGFR TKIs produce [152,153]. A randomized phase III trial comparing vandetanib to erlotinib showed no significant efficacy difference but toxicity was greater with vandetanib [154]. The phase III, double-blind, placebocontrolled ZODIAC trial, which involved vandetanib in addition to docetaxel, showed that vandetanib 100 mg significantly improved median PFS (14.0 weeks vs. 17.3 weeks; HR, 0.79) in second-line therapy for patients with locally advanced or metastatic NSCLC [155]. A similar randomized trial comparing pemetrexed with pemetrexed plus vandetanib showed no significant difference in PFS or OS although both were numerically longer in the vandetanib arm [156]. However, patients in the vandetanib arms of both trials exhibited more toxicities. Unfortunately, no studies to date have identified clinical or molecular markers that would predict benefit from this agent [154,156]. The phase III ZEPHYR trial is comparing vandetanib with BSC in patients who have progressed under erlotinib. 10.3. XL-647 XL-647 (EXEL-7647) is a reversible inhibitor of EGFR, HER2, vascular endothelial growth factor receptors-2 and -3, and the ephrin type B subclass 4 receptor (EphB4) [125]. Despite the fact that this agent is a reversible inhibitor, preclinical studies showed that XL647 had in vitro and in vivo activity against H1975 cells harboring the double L858R/T790M resistance mutation [125]. It is unclear which inhibitory effects of XL-647 are responsible for the activity observed in these cells. Preliminary results of a phase II trial of XL-647 in patients with NSCLC who had acquired resistance to erlotinib or gefitinib (n = 23) showed a PR in 1 patient and SD in 7 patients [157]. XL-647 was well tolerated, and the major AEs were similar to those that occurred with the EGFR TKIs. In another trial, XL-647 was administered to 41 patients with chemotherapy-naïve NSCLC meeting ≥1 of the following criteria: Asian ethnicity, female gender, and minimal (<15 pack-years) or no smoking history [158]. PRs were achieved in 10 (28%) of 36 evaluable patients, and 36% achieved SD for ≥3 months. Among the patients who achieved a PR, 70% had detectable EGFR mutations. Studies of XL-647 in NSCLC are ongoing. 11. Conclusion EGFR is an established target for NSCLC treatment, and the currently available EGFR-targeted agents have provided significant benefits and may have expanding indications for selected populations. However, objective responses in the general population are uncommon with the currently available EGFR-targeted therapies, and most patients who initially respond eventually develop acquired resistance. Preclinical evidence supports the concept that the concurrent inhibition of multiple HER family members may be more effective than sole EGFR inhibition. Several EGFR/HER2targeted agents and pan-HER inhibitors are in clinical development. Although studies with the reversible EGFR/HER2 inhibitor lapatinib have not been promising, irreversible TKIs are an emerging class of agents that may have the potential to overcome and prevent the emergence of acquired resistance that occurs with reversible EGFR TKIs. It remains to be seen whether this newer generation of agents will play a role as a superior inhibitor of EGFR by overcoming/preventing resistance or whether they will demonstrate wider effectiveness by blocking both EGFR and HER2 signaling. Correlation of outcomes with biomarkers such as HER2 expression or mutation and EGFR mutation status may help discern between these 2 characteristics of these compounds. The results from ongoing phase II and III trials of these agents in patients with NSCLC, particularly those who are resistant to reversible EGFR TKIs, are eagerly awaited. Conflict of interest statement RCD, ABO, NP have no conflicts of interest to disclose. DRC has served on advisory boards for Boehringer Ingelheim Pharmaceuticals. PAB has served as a consultant for Boehringer Ingelheim Pharmaceuticals, AstraZeneca, OSI/Genentech, GlaxoSmithKline, and Bristol-Myers Squibb/ImClone. R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 Acknowledgments This work was supported by Boehringer-Ingelheim Pharmaceuticals, Inc. Writing and editorial assistance was provided by Johnathan Maher, PhD, of BlueSpark Healthcare Communications, and was contracted by Boehringer-Ingelheim Pharmaceuticals, Inc. PAB, RCD, ABO, and NP meet criteria for authorship as recommended by the International Committee of Medical Journal Editors (ICMJE), were fully responsible for all content and editorial decisions, and were involved in all stages of manuscript development. PAB, RCD, ABO, and NP received honoraria for this article. The authors take full responsibility for the content and views in this article. Research support: NP is supported by an IASLC Young Investigator Award and a Fulbright-Schneider Yehuda Danon Post-Doctoral Fellowship by the United States–Israel Education Foundation. References [1] American Cancer Society. Cancer facts and figures 2008. Atlanta: American Cancer Society; 2008. p. 1–68. [2] World Health Organization: The top ten causes of death. Fact sheet no. 310. Last update: November 2008. Available at: http://www.who.int/ mediacentre/factsheets/fs310/en/index.html. Accessed August 6, 2009. [3] World Health Organization. Cancer. Fact sheet no. 297. Last update: February 2009. Available at: http://www.who.int/mediacentre/factsheets/ fs297/en/print.html. Accessed August 6, 2009. [4] Herbst RS, Heymach JV, Lippman SM. Lung cancer. N Engl J Med 2008;359:1367–80. [5] Langer CJ, Demmy TL, Ettinger D. NCCN clinical practice guidelines in oncology symposium: non-small cell lung cancer. Last update: November 29, 2007. Available at: http://www.medscape.com/viewprogram/8178. Accessed August 6, 2009. [6] American Cancer Society. Non-small cell lung cancer detailed guide, 2008. Atlanta: American Cancer Society; 2008. p. 1–61. [7] Pirker R, Szczesna A, von Pawel J, Krzakowski M, Ramlau R, Park K, et al. FLEX: a randomized, multicenter, phase III study of cetuximab in combination with cisplatin/vinorelbine (CV) versus CV alone in the first-line treatment of patients with advanced non-small cell lung cancer (NSCLC) (abstract no. 3). J Clin Oncol 2008;26:6s. [8] Georgoulias V, Papadakis E, Alexopoulos A, Tsiafaki X, Rapti A, Veslemes M, et al. Platinum-based and non-platinum-based chemotherapy in advanced non-small-cell lung cancer: a randomised multicentre trial. Lancet 2001;357:1478–84. [9] Treat J, Belani CP, Edelman M. A randomized phase III trial of gemcitabine in combination with carboplatin or paclitaxel versus paclitaxel plus carboplatin in advanced (stage IIIb, IV) non-small cell lung cancer: update of the Alpha Oncology Trial (A1-99002L) (abstract). J Clin Oncol 2005;23:627s. [10] Fossella F, Pereira JR, von Pawel J, Pluzanska A, Gorbounova V, Kaukel E, et al. Randomized, multinational, phase III study of docetaxel plus platinum combinations versus vinorelbine plus cisplatin for advanced non-small-cell lung cancer: the TAX 326 study group. J Clin Oncol 2003;21:3016–24. [11] Belani CP, Lee JS, Socinski MA, Robert F, Waterhouse D, Rowland K, et al. Randomized phase III trial comparing cisplatin-etoposide to carboplatinpaclitaxel in advanced or metastatic non-small cell lung cancer. Ann Oncol 2005;16:1069–75. [12] Schiller JH, Harrington D, Belani CP, Langer C, Sandler A, Krook J, et al. Comparison of four chemotherapy regimens for advanced non-small-cell lung cancer. N Engl J Med 2002;346:92–8. [13] Kelly K, Crowley J, Bunn Jr PA, Presant CA, Grevstad PK, Moinpour CM, et al. Randomized phase III trial of paclitaxel plus carboplatin versus vinorelbine plus cisplatin in the treatment of patients with advanced non-small-cell lung cancer: a Southwest Oncology Group trial. J Clin Oncol 2001;19:3210–8. [14] Smit EF, van Meerbeeck JP, Lianes P, Debruyne C, Legrand C, Schramel F, et al. Three-arm randomized study of two cisplatin-based regimens and paclitaxel plus gemcitabine in advanced non-small-cell lung cancer: a phase III trial of the European Organization for Research and Treatment of Cancer Lung Cancer Group—EORTC 08975. J Clin Oncol 2003;21:3909–17. [15] Sandler A, Gray R, Perry MC, Brahmer J, Schiller JH, Dowlati A, et al. Paclitaxelcarboplatin alone or with bevacizumab for non-small-cell lung cancer. N Engl J Med 2006;355:2542–50. [16] Shepherd FA, Pereira JR, Ciuleanu T, Tan EH, Hirsh V, Thongprasert S, et al. Erlotinib in previously treated non-small-cell lung cancer. N Engl J Med 2005;353:123–32. [17] Perez-Soler R, Chachoua A, Hammond LA, Rowinsky EK, Huberman M, Karp D, et al. Determinants of tumor response and survival with erlotinib in patients with non-small-cell lung cancer. J Clin Oncol 2004;22:3238–47. [18] Shepherd FA, Dancey J, Ramlau R, Mattson K, Gralla R, O’Rourke M, et al. Prospective randomized trial of docetaxel versus best supportive care in patients with non-small-cell lung cancer previously treated with platinumbased chemotherapy. J Clin Oncol 2000;18:2095–103. 9 [19] Fossella FV, DeVore R, Kerr RN, Crawford J, Natale RR, Dunphy F, et al. Randomized phase III trial of docetaxel versus vinorelbine or ifosfamide in patients with advanced non-small-cell lung cancer previously treated with platinumcontaining chemotherapy regimens. The TAX 320 Non-Small Cell Lung Cancer Study Group. J Clin Oncol 2000;18:2354–62. [20] Hanna N, Shepherd FA, Fossella FV, Pereira JR, de Marinis F, von Pawel J, et al. Randomized phase III trial of pemetrexed versus docetaxel in patients with non-small-cell lung cancer previously treated with chemotherapy. J Clin Oncol 2004;22:1589–97. [21] Bazley LA, Gullick WJ. The epidermal growth factor receptor family. Endocr Relat Cancer 2005;12(Suppl. 1):S17–27. [22] Herbst RS, Shin DM. Monoclonal antibodies to target epidermal growth factor receptor-positive tumors: a new paradigm for cancer therapy. Cancer 2002;94:1593–611. [23] Kumar A, Petri ET, Halmos B, Boggon TJ. Structure and clinical relevance of the epidermal growth factor receptor in human cancer. J Clin Oncol 2008;26:1742–51. [24] Guy PM, Platko JV, Cantley LC, Cerione RA, Carraway III KL. Insect cellexpressed p180erbB3 possesses an impaired tyrosine kinase activity. Proc Natl Acad Sci USA 1994;91:8132–6. [25] Carraway III KL, Sliwkowski MX, Akita R, Platko JV, Guy PM, Nuijens A, et al. The erbB3 gene product is a receptor for heregulin. J Biol Chem 1994;269:14303–6. [26] Ciardiello F, Tortora G. EGFR antagonists in cancer treatment. N Engl J Med 2008;358:1160–74. [27] Graus-Porta D, Beerli RR, Daly JM, Hynes NE. ErbB-2, the preferred heterodimerization partner of all ErbB receptors, is a mediator of lateral signaling. EMBO J 1997;16:1647–55. [28] Lynch TJ, Bell DW, Sordella R, Gurubhagavatula S, Okimoto RA, Brannigan BW, et al. Activating mutations in the epidermal growth factor receptor underlying responsiveness of non-small-cell lung cancer to gefitinib. N Engl J Med 2004;350:2129–39. [29] Paez JG, Janne PA, Lee JC, Tracy S, Greulich H, Gabriel S, et al. EGFR mutations in lung cancer: correlation with clinical response to gefitinib therapy. Science 2004;304:1497–500. [30] Okabe T, Okamoto I, Tamura K, Terashima M, Yoshida T, Satoh T, et al. Differential constitutive activation of the epidermal growth factor receptor in non-small cell lung cancer cells bearing EGFR gene mutation and amplification. Cancer Res 2007;67:2046–53. [31] Yun CH, Boggon TJ, Li Y, Woo MS, Greulich H, Meyerson M, et al. Structures of lung cancer-derived EGFR mutants and inhibitor complexes: mechanism of activation and insights into differential inhibitor sensitivity. Cancer Cell 2007;11:217–27. [32] Kokai Y, Myers JN, Wada T, Brown VI, LeVea CM, Davis JG, et al. Synergistic interaction of p185c-neu and the EGF receptor leads to transformation of rodent fibroblasts. Cell 1989;58:287–92. [33] Pinkas-Kramarski R, Soussan L, Waterman H, Levkowitz G, Alroy I, Klapper L, et al. Diversification of Neu differentiation factor and epidermal growth factor signaling by combinatorial receptor interactions. EMBO J 1996;15:2452– 67. [34] Riese DJ, van Raaij TM, Plowman GD, Andrews GC, Stern DF. The cellular response to neuregulins is governed by complex interactions of the erbB receptor family. Mol Cell Biol 1995;15:5770–6. [35] Wissner A, Mansour TS. The development of HKI-272 and related compounds for the treatment of cancer. Arch Pharm (Weinheim) 2008;341:465– 77. [36] Fukuoka M, Yano S, Giaccone G, Tamura T, Nakagawa K, Douillard JY, et al. Multi-institutional randomized phase II trial of gefitinib for previously treated patients with advanced non-small-cell lung cancer (The IDEAL 1 Trial) [corrected]. J Clin Oncol 2003;21:2237–46. [37] Kris MG, Natale RB, Herbst RS, Lynch Jr TJ, Prager D, Belani CP, et al. Efficacy of gefitinib, an inhibitor of the epidermal growth factor receptor tyrosine kinase, in symptomatic patients with non-small cell lung cancer: a randomized trial. JAMA 2003;290:2149–58. [38] Thatcher N, Chang A, Parikh P, Pereira JR, Ciuleanu T, von Pawel J, et al. Gefitinib plus best supportive care in previously treated patients with refractory advanced non-small-cell lung cancer: results from a randomised, placebocontrolled, multicentre study (Iressa Survival Evaluation in Lung Cancer). Lancet 2005;366:1527–37. [39] Kim ES, Hirsh V, Mok T, Socinski MA, Gervais R, Wu YL, et al. Gefitinib versus docetaxel in previously treated non-small-cell lung cancer (INTEREST): a randomised phase III trial. Lancet 2008;372:1809–18. [40] Engelman JA, Zejnullahu K, Gale CM, Lifshits E, Gonzales AJ, Shimamura T, et al. PF00299804, an irreversible pan-ERBB inhibitor, is effective in lung cancer models with EGFR and ERBB2 mutations that are resistant to gefitinib. Cancer Res 2007;67:11924–32. [41] Brugger W, Kim J-H, Hansen O, Sullivan R, White S, Lee J-S, et al. Biomarker analyses from SATURN, a phase III placebo-controlled study of erlotinib as first-line maintenance therapy for advanced NSCLC (abstract no. 9.176). Eur J Cancer Suppl 2009;7:559. [42] Sharma SV, Bell DW, Settleman J, Haber DA. Epidermal growth factor receptor mutations in lung cancer. Nat Rev Cancer 2007;7:169–81. [43] Jackman DM, Yeap BY, Sequist LV, Lindeman N, Holmes AJ, Joshi VA, et al. Exon 19 deletion mutations of epidermal growth factor receptor are associated with prolonged survival in non-small cell lung cancer patients treated with gefitinib or erlotinib. Clin Cancer Res 2006;12:3908–14. 10 R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 [44] Maruyama R, Nishiwaki Y, Tamura T, Yamamoto N, Tsuboi M, Nakagawa K, et al. Phase III study, V-15-32, of gefitinib versus docetaxel in previously treated Japanese patients with non-small-cell lung cancer. J Clin Oncol 2008;26:4244–52. [45] Crino L, Cappuzzo F, Zatloukal P, Reck M, Pesek M, Thompson JC, et al. Gefitinib versus vinorelbine in chemotherapy-naive elderly patients with advanced non-small-cell lung cancer (INVITE): a randomized, phase II study. J Clin Oncol 2008;26:4253–60. [46] Perng RP, Yang CH, Chen YM, Chang GC, Lin MC, Hsieh RK, et al. High efficacy of erlotinib in Taiwanese NSCLC patients in an expanded access program study previously treated with chemotherapy. Lung Cancer 2008;62:78–84. [47] Kubota K, Nishiwaki Y, Tamura T, Nakagawa K, Matsui K, Watanabe K, et al. Efficacy and safety of erlotinib monotherapy for Japanese patients with advanced non-small cell lung cancer: a phase II study. J Thorac Oncol 2008;3:1439–45. [48] Hesketh PJ, Chansky K, Wozniak AJ, Hirsch FR, Spreafico A, Moon J, et al. Southwest Oncology Group phase II trial (S0341) of erlotinib (OSI-774) in patients with advanced non-small cell lung cancer and a performance status of 2. J Thorac Oncol 2008;3:1026–31. [49] Lilenbaum R, Axelrod R, Thomas S, Dowlati A, Seigel L, Albert D, et al. Randomized phase II trial of erlotinib or standard chemotherapy in patients with advanced non-small-cell lung cancer and a performance status of 2. J Clin Oncol 2008;26:863–9. [50] Giaccone G, Gallegos RM, Le Chevalier T, Thatcher N, Smit E, Rodriguez JA, et al. Erlotinib for frontline treatment of advanced non-small cell lung cancer: a phase II study. Clin Cancer Res 2006;12:6049–55. [51] Kim YH, Ishii G, Goto K, Nagai K, Tsuta K, Shiono S, et al. Dominant papillary subtype is a significant predictor of the response to gefitinib in adenocarcinoma of the lung. Clin Cancer Res 2004;10:7311–7. [52] Miller VA, Kris MG, Shah N, Patel J, Azzoli C, Gomez J, et al. Bronchioloalveolar pathologic subtype and smoking history predict sensitivity to gefitinib in advanced non-small-cell lung cancer. J Clin Oncol 2004;22:1103–9. [53] Sequist LV, Bell DW, Lynch TJ, Haber DA. Molecular predictors of response to epidermal growth factor receptor antagonists in non-small-cell lung cancer. J Clin Oncol 2007;25:587–95. [54] Mitsudomi T, Kosaka T, Endoh H, Horio Y, Hida T, Mori S, et al. Mutations of the epidermal growth factor receptor gene predict prolonged survival after gefitinib treatment in patients with non-small cell lung cancer with postoperative recurrence. J Clin Oncol 2005;23:2513–20. [55] Riely GJ, Pao W, Pham D, Li AR, Rizvi N, Venkatraman ES, et al. Clinical course of patients with non-small cell lung cancer and epidermal growth factor receptor exon 19 and exon 21 mutations treated with gefitinib or erlotinib. Clin Cancer Res 2006;12:839–44. [56] Paz-Ares L, Sanchez JM, Garcia-Velasco B, Massuti B, López-Vivanco G, Provencio M, et al. A prospective phase II trial of erlotinib in advanced non-small cell lung cancer (NSCLC) patients (p) with mutations in the tyrosine kinase (TK) domain of the epidermal growth factor receptor (EGFR) (abstract no. 7020). J Clin Oncol 2006;24(Suppl.):369s. [57] Sequist LV, Martins RG, Spigel D, Grunberg SM, Spira A, Janne PA, et al. Firstline gefitinib in patients with advanced non-small-cell lung cancer harboring somatic EGFR mutations. J Clin Oncol 2008;26:2442–9. [58] Sugio K, Uramoto H, Onitsuka T, Mizukami M, Ichiki Y, Sugaya M, et al. Prospective phase II study of gefitinib in non-small cell lung cancer with epidermal growth factor receptor gene mutations. Lung Cancer 2008;64:314–8. [59] Tamura K, Okamoto I, Kashii T, Negoro S, Hirashima T, Kudoh S, et al. Multicentre prospective phase II trial of gefitinib for advanced non-small cell lung cancer with epidermal growth factor receptor mutations: results of the West Japan Thoracic Oncology Group trial (WJTOG0403). Br J Cancer 2008;98:907–14. [60] West H, Chansky K, Franklin WA, Hirsch FR, Crowley JJ, Lau DH, et al. Long-term survival with gefitinib (ZD 1839) therapy for advanced bronchioloalveolar cancer (BAC): Southwest Oncology Group (SWOG) study S0126 (abstract no. 8047). J Clin Oncol 2008;26:435s. [61] Cappuzzo F, Ligorio C, Janne PA, et al. Prospective study of gefitinib in epidermal growth factor receptor fluorescence in situ hybridizationpositive/phospho-Akt-positive or never smoker patients with advanced nonsmall-cell lung cancer: the ONCOBELL trial. J Clin Oncol 2007;25:2248–55. [62] Herbst RS, Chansky K, Kelly K, Atkins JN, Davies AM, Dakhil SR, et al. A phase II randomized selection trial evaluating concurrent chemotherapy plus cetuximab or chemotherapy followed by cetuximab in patients with advanced non-small cell lung cancer (NSCLC): final report of SWOG 0342 (abstract no. 7545). J Clin Oncol 2007:25. [63] Mok T, Wu Y-L, Thongprasert S, et al. Phase III, randomised, open-label, firstline study of gefitinib (G) vs carboplatin/paclitaxel (C/P) in clinically selected patients (PTS) with advanced non-small cell lung cancer (NSCLC) (IPASS) (abstract no. LBA2). Ann Oncol 2008;19(Suppl. 8). p. viii, 1–4. [64] Wakeling AE, Guy SP, Woodburn JR, Ashton SE, Curry BJ, Barker AJ, et al. ZD1839 (Iressa): an orally active inhibitor of epidermal growth factor signaling with potential for cancer therapy. Cancer Res 2002;62:5749–54. [65] West HL, Franklin WA, McCoy J, Gumerlock PH, Vance R, Lau DH, et al. Gefitinib therapy in advanced bronchioloalveolar carcinoma: Southwest Oncology Group Study S0126. J Clin Oncol 2006;24:1807–13. [66] Inoue A, Kobayashi K, Usui K, Maemondo M, Okinaga S, Mikami I, et al. First-line gefitinib for patients with advanced non-small-cell lung cancer harboring epidermal growth factor receptor mutations without indication for chemotherapy. J Clin Oncol 2009;27:1394–400. [67] Lee JS, Park K, Kim S-W, Lee DH, Kim HT, Han J-Y, et al. A randomized phase III study of gefitinib (IRESSATM ) versus standard chemotherapy (gemcitabine plus cisplatin) as a first-line treatment for never-smokers with advanced or metastatic adenocarcinoma of the lung. Presented at the 13th world conference on lung cancer. 2009. [68] Kobayashi K. First-line gefitinib versus first-line chemotherapy by carboplatin (CBDCA) plus paclitaxel (TXL) in non-small cell lung cancer (NSCLC) patients (pts) with EGFR mutations: a phase III study (002) by North East Japan Gefitinib Study Group (abstract no. 8016). J Clin Oncol 2009;27:15s. [69] Rosell R, Moran T, Queralt C, Porta R, Cardenal F, Camps C. Screening for epidermal growth factor receptor mutations in lung cancer. N Engl J Med 2009;361:958–67. [70] Hirsch FR, Dziadziuszko R, Varella-Garcia L, Franklin W, Bunn P, Kabbinavar F. Randomized phase II study of erlotinib (E) or intercalated E with carboplatin/paclitaxel (CP) in chemotherapy-naive advanced NSCLC: correlation of biomarker status and clinical benefit (abstract no. 8026). J Clin Oncol 2009;27:15s. [71] Varella-Garcia M. Stratification of non-small cell lung cancer patients for therapy with epidermal growth factor receptor inhibitors: the EGFR fluorescence in situ hybridization assay. Diagn Pathol 2006;1:19. [72] Helfrich BA, Raben D, Varella-Garcia M, Gustafson D, Chan DC, Bemis L, et al. Antitumor activity of the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib (ZD1839, Iressa) in non-small cell lung cancer cell lines correlates with gene copy number and EGFR mutations but not EGFR protein levels. Clin Cancer Res 2006;12:7117–25. [73] Hirsch FR, Varella-Garcia M, Bunn Jr PA, Franklin WA, Dziadziuszko R, Thatcher N, et al. Molecular predictors of outcome with gefitinib in a phase III placebo-controlled study in advanced non-small-cell lung cancer. J Clin Oncol 2006;24:5034–42. [74] Zhu CQ, da Cunha SG, Ding K, Sakurada A, Cutz JC, Liu N, et al. Role of KRAS and EGFR as biomarkers of response to erlotinib in National Cancer Institute of Canada Clinical Trials Group Study BR.21. J Clin Oncol 2008;26:4268– 75. [75] Cappuzzo F, Hirsch FR, Rossi E, Bartolini S, Ceresoli GL, Bemis L, et al. Epidermal growth factor receptor gene and protein and gefitinib sensitivity in non-small-cell lung cancer. J Natl Cancer Inst 2005;97:643–55. [76] Hirsch FR, Varella-Garcia M, McCoy J, West H, Xavier AC, Gumerlock P, et al. Increased epidermal growth factor receptor gene copy number detected by fluorescence in situ hybridization associates with increased sensitivity to gefitinib in patients with bronchioloalveolar carcinoma subtypes: a Southwest Oncology Group Study. J Clin Oncol 2005;23:6838–45. [77] Tsao MS, Sakurada A, Cutz JC, Zhu CQ, Kamel-Reid S, Squire J, et al. Erlotinib in lung cancer—molecular and clinical predictors of outcome. N Engl J Med 2005;353:133–44. [78] Hirsch FR, Varella-Garcia M, Cappuzzo F, McCoy J, Bemis L, Xavier AC, et al. Combination of EGFR gene copy number and protein expression predicts outcome for advanced non-small-cell lung cancer patients treated with gefitinib. Ann Oncol 2007;18:752–60. [79] Pao W, Wang TY, Riely GJ, Miller VA, Pan Q, Ladanyi M, et al. KRAS mutations and primary resistance of lung adenocarcinomas to gefitinib or erlotinib. PLoS Med 2005;2:e17. [80] Miller VA, Riely GJ, Zakowski MF, Li AR, Patel JD, Heelan RT, et al. Molecular characteristics of bronchioloalveolar carcinoma and adenocarcinoma, bronchioloalveolar carcinoma subtype, predict response to erlotinib. J Clin Oncol 2008;26:1472–8. [81] Massarelli E, Varella-Garcia M, Tang X, Xavier AC, Ozburn NC, Liu DD, et al. KRAS mutation is an important predictor of resistance to therapy with epidermal growth factor receptor tyrosine kinase inhibitors in non-small-cell lung cancer. Clin Cancer Res 2007;13:2890–6. [82] Kobayashi S, Boggon TJ, Dayaram T, Janne PA, Kocher O, Meyerson M, et al. EGFR mutation and resistance of non-small-cell lung cancer to gefitinib. N Engl J Med 2005;352:786–92. [83] Yun CH, Mengwasser KE, Toms AV, Woo MS, Greulich H, Wong KK, et al. The T790M mutation in EGFR kinase causes drug resistance by increasing the affinity for ATP. Proc Natl Acad Sci USA 2008;105:2070–5. [84] Engelman JA, Janne PA. Mechanisms of acquired resistance to epidermal growth factor receptor tyrosine kinase inhibitors in non-small cell lung cancer. Clin Cancer Res 2008;14:2895–9. [85] Maheswaran S, Sequist LV, Nagrath S, Ulkus L. Detection in mutations in EGFR in circulating lung-cancer cells. N Engl J Med 2008;359:366–77. [86] Carter TA, Wodicka LM, Shah NP, Velasco AM, Fabian MA, Treiber DK, et al. Inhibition of drug-resistant mutants of ABL, KIT, and EGF receptor kinases. Proc Natl Acad Sci USA 2005;102:11011–6. [87] Engelman JA, Zejnullahu K, Mitsudomi T, Song Y, Hyland C, Park JO, et al. MET amplification leads to gefitinib resistance in lung cancer by activating ERBB3 signaling. Science 2007;316:1039–43. [88] Morgillo F, Kim WY, Kim ES, Ciardiello F, Hong WK, Lee HY. Implication of the insulin-like growth factor-IR pathway in the resistance of non-small cell lung cancer cells to treatment with gefitinib. Clin Cancer Res 2007;13:2795–803. [89] Prewett M, Rockwell P, Rockwell RF, Giorgio NA, Mendelsohn J, Scher HI, et al. The biologic effects of C225, a chimeric monoclonal antibody to the EGFR, on human prostate carcinoma. J Immunother Emphasis Tumor Immunol 1996;19:419–27. [90] Lynch TJ, Lilenbaum R, Bonomi P, Ansari R, Govindan R, Janne PA, et al. A phase II trial of cetuximab as therapy for recurrent non-small cell lung cancer (NSCLC) (abstract no. 7084). J Clin Oncol 2004:22. R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 [91] Belani CP, Schreeder MT, Steis RG, Guidice RA, Marsland TA, Butler EH, et al. Cetuximab in combination with carboplatin and docetaxel for patients with metastatic or advanced-stage nonsmall cell lung cancer: a multicenter phase 2 study. Cancer 2008;113:2512–7. [92] Borghaei H, Langer CJ, Millenson M, Ruth KJ, Litwin S, Tuttle H, et al. Phase II study of paclitaxel, carboplatin, and cetuximab as first line treatment, for patients with advanced non-small cell lung cancer (NSCLC): results of OPN017. J Thorac Oncol 2008;3:1286–92. [93] Butts CA, Bodkin D, Middleman EL, Englund CW, Ellison D, Alam Y, et al. Randomized phase II study of gemcitabine plus cisplatin or carboplatin [corrected], with or without cetuximab, as first-line therapy for patients with advanced or metastatic non small-cell lung cancer. J Clin Oncol 2007;25:5777–84. [94] Rosell R, Robinet G, Szczesna A, Ramlau R, Constenla M, Mennecier BC, et al. Randomized phase II study of cetuximab plus cisplatin/vinorelbine compared with cisplatin/vinorelbine alone as first-line therapy in EGFR-expressing advanced non-small-cell lung cancer. Ann Oncol 2008;19:362–9. [95] Lynch TJ, Patel T, Dreisbach L, McCleod M, Heim W, Hermann RC, et al. Overall survival (os) results from the phase III trial BMS 099: cetuximab + taxane/carboplatin as 1st-line treatment for advanced NSCLC (abstract). J Thorac Oncol 2008;3:S305. [96] National Comprehensive Cancer Network. NCCN clinical practice guidelines in oncology: non-small cell lung cancer, v.2; 2008. [97] Karapetis CS, Khambata-Ford S, Jonker DJ, O’Callaghan CJ, Tu D, Tebbutt NC, et al. K-ras mutations and benefit from cetuximab in advanced colorectal cancer. N Engl J Med 2008;359:1757–65. [98] Cunningham D, Humblet Y, Siena S, Khayat D, Bleiberg H, Santoro A, et al. Cetuximab monotherapy and cetuximab plus irinotecan in irinotecanrefractory metastatic colorectal cancer. N Engl J Med 2004;351:337– 45. [99] Khambata-Ford S, Harbison C, Woytowitz D, Awad M, Horak C, Xu LA, et al. K-Ras mutation (mut), EGFR-related, and exploratory markers as response predictors of cetuximab in first-line advanced NSCLC: retrospective analyses of the BMS099 trial (abstract no. 8021). J Clin Oncol 2009;27:15s. [100] O’Byrne KJ, Bondarenko I, Barrios C, Eschbach C, Martens U, Hotko Y, et al. Molecular and clinical predictors of outcome for cetuximab in non-small cell lung cancer (NSCLC): data from the FLEX study (abstract no. 8007). J Clin Oncol 2009;27:15s. [101] Mack PC, Holland WS, Redman M, Lara Jr PN, Snyder LJ, Hirsch FR. KRAS mutation analysis in cetuximab-treated advanced stage non-small cell lung cancer (NSCLC): SWOG experience with S0342 and S0536 (abstract no. 8022). J Clin Oncol 2009;27:15s. [102] Hirsch FR, Herbst RS, Olsen C, Chansky K, Crowley J, Kelly K, et al. Increased EGFR gene copy number detected by fluorescent in situ hybridization predicts outcome in non-small-cell lung cancer patients treated with cetuximab and chemotherapy. J Clin Oncol 2008;26:3351–7. [103] Hirsch FR, Varella-Garcia M, Bunn Jr PA, Di Maria MV, Veve R, Bremmes RM, et al. Epidermal growth factor receptor in non-small-cell lung carcinomas: correlation between gene copy number and protein expression and impact on prognosis. J Clin Oncol 2003;21:3798–807. [104] Cappuzzo F, Marchetti A, Skokan M, Rossi E, Gajapathy S, Felicioni L, et al. Increased MET gene copy number negatively affects survival of surgically resected non-small-cell lung cancer patients. J Clin Oncol 2009;27:1667–74. [105] Worthylake R, Opresko LK, Wiley HS. ErbB-2 amplification inhibits downregulation and induces constitutive activation of both ErbB-2 and epidermal growth factor receptors. J Biol Chem 1999;274:8865–74. [106] Normanno N, Bianco C, Strizzi L, Mancino M, Maiello MR, De Luca A, et al. The ErbB receptors and their ligands in cancer: an overview. Curr Drug Targets 2005;6:243–57. [107] Brabender J, Danenberg KD, Metzger R, Schneider PM, Park J, Salonga D, et al. Epidermal growth factor receptor and HER2-neu mRNA expression in non-small cell lung cancer is correlated with survival. Clin Cancer Res 2001;7:1850–5. [108] Onn A, Correa AM, Gilcrease M, Isobe T, Massarelli E, Bucana CD, et al. Synchronous overexpression of epidermal growth factor receptor and HER2-neu protein is a predictor of poor outcome in patients with stage I non-small cell lung cancer. Clin Cancer Res 2004;10:136–43. [109] Tateishi M, Ishida T, Kohdono S, Hamatake M, Fukuyama Y, Sugimachi K. Prognostic influence of the co-expression of epidermal growth factor receptor and c-erbB-2 protein in human lung adenocarcinoma. Surg Oncol 1994;3:109– 13. [110] Ren XL, Xu YM, Bao W, Fu HJ, Wu CG, Zhao Y, et al. Inhibition of non-small cell lung cancer cell proliferation and tumor growth by vector-based small interfering RNAs targeting HER2/neu. Cancer Lett 2009;281:134–43. [111] Cappuzzo F, Varella-Garcia M, Shigematsu H, Domenichini I, Bartolini S, Ceresoli GL, et al. Increased HER2 gene copy number is associated with response to gefitinib therapy in epidermal growth factor receptor-positive non-small-cell lung cancer patients. J Clin Oncol 2005;23:5007–18. [112] Nakamura H, Kawasaki N, Taguchi M, Kabasawa K. Association of HER-2 overexpression with prognosis in nonsmall cell lung carcinoma: a metaanalysis. Cancer 2005;103:1865–73. [113] Hirsch FR, Franklin WA, Veve R, Varella-Garcia M, Bunn Jr PA. HER2/neu expression in malignant lung tumors. Semin Oncol 2002;29:51–8. [114] Shigematsu H, Takahashi T, Nomura M, Majmudar K, Suzuki M, Lee H, et al. Somatic mutations of the HER2 kinase domain in lung adenocarcinomas. Cancer Res 2005;65:1642–6. 11 [115] Wang SE, Narasanna A, Perez-Torres M, Xiang B, Wu FY, Yang S, et al. HER2 kinase domain mutation results in constitutive phosphorylation and activation of HER2 and EGFR and resistance to EGFR tyrosine kinase inhibitors. Cancer Cell 2006;10:25–38. [116] Cappuzzo F, Bemis L, Varella-Garcia M. HER2 mutation and response to trastuzumab therapy in non-small-cell lung cancer. N Engl J Med 2006;354:2619–21. [117] Finn RS, Wilson CA, Chen J, Glaspy P, Dering J, Cook A, et al. Biologic effects of CP-724,714, a selective HER-2/neu kinase inhibitor, on human breast cancer cells with variable expression of EGFR and HER-2 (abstract no. 4556). Proc Am Assoc Cancer Res 2004:45. [118] Friess T, Scheuer W, Hasmann M. Combination treatment with erlotinib and pertuzumab against human tumor xenografts is superior to monotherapy. Clin Cancer Res 2005;11:5300–9. [119] Moasser MM, Basso A, Averbuch SD, Rosen N. The tyrosine kinase inhibitor ZD1839 (“Iressa”) inhibits HER2-driven signaling and suppresses the growth of HER2-overexpressing tumor cells. Cancer Res 2001;61:7184–8. [120] Moulder SL, Yakes FM, Muthuswamy SK, Bianco R, Simpson JF, Arteaga CL. Epidermal growth factor receptor (HER1) tyrosine kinase inhibitor ZD1839 (Iressa) inhibits HER2/neu (erbB2)-overexpressing breast cancer cells in vitro and in vivo. Cancer Res 2001;61:8887–95. [121] Normanno N, Campiglio M, De LA, Somenzi G, Maiello M, Ciardiello F, et al. Cooperative inhibitory effect of ZD1839 (Iressa) in combination with trastuzumab (Herceptin) on human breast cancer cell growth. Ann Oncol 2002;13:65–72. [122] Ye D, Mendelsohn J, Fan Z. Androgen and epidermal growth factor down-regulate cyclin-dependent kinase inhibitor p27Kip1 and costimulate proliferation of MDA PCa 2a and MDA PCa 2b prostate cancer cells. Clin Cancer Res 1999;5:2171–7. [123] Ye D, Mendelsohn J, Fan Z. Augmentation of a humanized anti-HER2 mAb 4D5 induced growth inhibition by a human-mouse chimeric anti-EGF receptor mAb C225. Oncogene 1999;18:731–8. [124] Li D, Ambrogio L, Shimamura T, Kubo S, Takahashi M, Chirieac LR, et al. BIBW2992, an irreversible EGFR/HER2 inhibitor highly effective in preclinical lung cancer models. Oncogene 2008;27:4702–11. [125] Gendreau SB, Ventura R, Keast P, Laird AD, Yakes FM, Zhang W, et al. Inhibition of the T790M gatekeeper mutant of the epidermal growth factor receptor by EXEL-7647. Clin Cancer Res 2007;13:3713–23. [126] Rusnak DW, Lackey K, Affleck K, Wood ER, Alligood KJ, Rhodes N, et al. The effects of the novel, reversible epidermal growth factor receptor/ErbB2 tyrosine kinase inhibitor, GW2016, on the growth of human normal and tumor-derived cell lines in vitro and in vivo. Mol Cancer Ther 2001;1:85–94. [127] Smylie M, Blumenschein G, Dowlati A. A phase II multicenter trial comparing two schedules of lapatinib (LAP) as first or second line monotherapy in subjects with advanced or metastatic non-small cell lung cancer (NSCLC) with either bronchioloalveolar carcinoma (BAC) or no smoking history (abstract no. 7611). J Clin Oncol 2007;25:412s. [128] Kwak EL, Sordella R, Bell DW, Godin-Heymann N, Okimoto RA, Brannigan BW, et al. Irreversible inhibitors of the EGFR receptor may circumvent acquired resistance to gefitinib. Proc Natl Acad Sci USA 2005;102:7665–70. [129] Eskens FA, Mom CH, Planting AS, Gietema JA, Amelsberg A, Huisman H, et al. A phase I dose escalation study of BIBW 2992, an irreversible dual inhibitor of epidermal growth factor receptor 1 (EGFR) and 2 (HER2) tyrosine kinase in a 2-week on, 2-week off schedule in patients with advanced solid tumours. Br J Cancer 2008;98:80–5. [130] Bean J, Riely GJ, Balak M, Marks JL, Ladanyi M, Miller VA, et al. Acquired resistance to epidermal growth factor receptor kinase inhibitors associated with a novel T854A mutation in a patient with EGFR-mutant lung adenocarcinoma. Clin Cancer Res 2008;14:7519–25. [131] Agus D, Terlizzi E, Stopfer P, Amelsberg A, Gordon MS. A phase I dose escalation study of BIBW 2992, an irreversible dual EGFR/HER2 receptor tyrosine kinase inhibitor, in a continuous schedule in patients with advanced solid tumours (abstract). J Clin Oncol 2006:24. [132] Lewis N, Marshall J, Amelsberg A, Cohen RB, Stopfer P, Hwang J, et al. A phase I dose escalation study of BIBW 2992, an irreversible dual EGFR/HER2 receptor tyrosine kinase inhibitor, in a 3 week on 1 week off schedule in patients with advanced solid tumors (abstract no. 3091). J Clin Oncol 2006:24. [133] Mom C, Eskens F, Gietema J, Nooter K, de Jonge MJA, Amelsberg A, et al. Phase I study with BIBW 2992, an irreversible dual tyrosine kinase inhibitor of epidermal growth factor receptor 1 (EGFR) and 2 (HER2) in a 2 week on 2 week off schedule (abstract no. 3025). J Clin Oncol 2006:24. [134] Spicer J, Calvert H, Vidal L, Azribi F, Perrett R, Shahidi M, et al. Activity of BIBW 2992, an oral irreversible dual EGFR/HER2 inhibitor, in non-small cell lung cancer (NSCLC) with mutated EGFR (abstract). J Thorac Oncol 2007:2. [135] Shih J, Yang C, Su WC. A phase II study of BIBW 2992, a novel irreversible dual EGFR and HER2 tyrosine kinase inhibitor (TKI), in patients with adenocarcinoma of the lung and activating EGFR mutations after failure of one line of chemotherapy (LUX-Lung 2) (abstract no. 8013). J Clin Oncol 2009:27. [136] Yang CH, Shih JY, Su WC, Hsia TC, Ho CL, Dudek AZ, et al. BIBW 2992, a novel irreversible EGFR/HER2 tyrosine kinase inhibitor, in chemonaive patients with adenocarcinoma of the lung and activating EGFR mutations. Presented at the 13th world conference on lung cancer. 2009. [137] Yang C, Hirsh V, Cadranel J, Chen Y, Park K, Kim S, et al. Phase IIb/III doubleblind randomized trial of BIBW 2992, an irreversible, dual inhibitor of EGFR and HER2 plus best supportive care (BSC) versus placebo plus BSC in patients with NSCLC failing 1-2 lines of chemotherapy (CT) and erlotinib or gefi- 12 [138] [139] [140] [141] [142] [143] [144] [145] [146] [147] [148] R.C. Doebele et al. / Lung Cancer 69 (2010) 1–12 tinib (LUX-Lung1): a preliminary report (abstract no. 8062). J Clin Oncol 2009;27:15s. Pao W, Miller VA, Politi KA, Riely GJ, Somwar R, Zakowski MF, et al. Acquired resistance of lung adenocarcinomas to gefitinib or erlotinib is associated with a second mutation in the EGFR kinase domain. PLoS Med 2005;2:e73. Wong KK, Fracasso PM, Bukowski RM, Lynch TJ, Munster PN, Shapiro GI, et al. A phase I study with neratinib (HKI-272), an irreversible pan ErbB receptor tyrosine kinase inhibitor, in patients with solid tumors. Clin Cancer Res 2009;15:2552–8. Godin-Heymann N, Ulkus L, Brannigan BW, McDermott U, Lamb J, Maheswaran S, et al. The T790M “gatekeeper” mutation in EGFR mediates resistance to low concentrations of an irreversible EGFR inhibitor. Mol Cancer Ther 2008;7:874–9. Ji H, Zhao X, Yuza Y, Shimamura T, Li D, Protopopov A, et al. Epidermal growth factor receptor variant III mutations in lung tumorigenesis and sensitivity to tyrosine kinase inhibitors. Proc Natl Acad Sci USA 2006;103:7817– 22. Shimamura T, Ji H, Minami Y, Thomas RK, Lowell AM, Shah K, et al. Nonsmall-cell lung cancer and Ba/F3 transformed cells harboring the ERBB2 G776insV G/C mutation are sensitive to the dual-specific epidermal growth factor receptor and ERBB2 inhibitor HKI-272. Cancer Res 2006;66:6487–91. Minami Y, Shimamura T, Shah K, LaFramboise T, Glatt KA, Liniker E, et al. The major lung cancer-derived mutants of ERBB2 are oncogenic and are associated with sensitivity to the irreversible EGFR/ERBB2 inhibitor HKI-272. Oncogene 2007;26:5023–7. Rabindran SK, Discafani CM, Rosfjord EC, Baxter M, Floyd MB, Golas J, et al. Antitumor activity of HKI-272, an orally active, irreversible inhibitor of the HER-2 tyrosine kinase. Cancer Res 2004;64:3958–65. Besse B, Eaton KD, Soria JC, Lynch TJ, Miller V, Wong KK, et al. Neratinib (HKI-272), an irreversible pan-ErbB receoptor tyrosine kinase inhibitor: preliminary results of a phase 2 trial in patients with advanced non-small cell lung cancer (abstract). Eur J Cancer 2008;6:64. Janne PA, Schellens JA, Engelman SG, Eckhardt SG, Millham R, Denis LJ, et al. Preliminary activity and safety results from a phase I clinical trial of PF00299804, an irreversible pan-HER inhibitor, in patients (pts) with NSCLC (abstract no.8027). J Clin Oncol 2008:26. Janne PA, Reckamp KL, Koczywas M. Efficacy and safety of PF-00299804 (PF299) in patients (pt) with advanced NSCLC after failure of at least one prior chemotherapy regimen and prior treatment with erlotinib (E): a two-arm, phase II trial (abstract no. 8063). J Clin Oncol 2009;27:15s. Langer CJ, Stephenson P, Thor A, Vangel M, Johnson DH. Trastuzumab in the treatment of advanced non-small-cell lung cancer: is there a role? [149] [150] [151] [152] [153] [154] [155] [156] [157] [158] Focus on Eastern Cooperative Oncology Group study 2598. J Clin Oncol 2004;22:1180–7. Gatzemeier U, Groth G, Butts C, van Zandwijk N, Shepherd F, Ardizzoni A, et al. Randomized phase II trial of gemcitabine-cisplatin with or without trastuzumab in HER2-positive non-small-cell lung cancer. Ann Oncol 2004;15:19–27. Franklin MC, Carey KD, Vajdos FF, Leahy DJ, de Vos AM, Sliwkowski MX, et al. Insights into ErbB signaling from the structure of the ErbB2-pertuzumab complex. Cancer Cell 2004;5:317–28. Herbst RS, Davies AM, Natale RB, Dang TP, Schiller JH, Garland LL, et al. Efficacy and safety of single-agent pertuzumab, a human epidermal receptor dimerization inhibitor, in patients with non small cell lung cancer. Clin Cancer Res 2007;13:6175–81. Ichihara E, Ohashi K, Takigawa N, Osawa M, Ogino A, Tanimoto M, et al. Effects of vandetanib on lung adenocarcinoma cells harboring epidermal growth factor receptor T790M mutation in vivo. Cancer Res 2009;69: 5091–8. Ciardiello F, Bianco R, Caputo R, Caputo R, Damiano V, Troiani T, et al. Antitumor activity of ZD6474, a vascular endothelial growth factor receptor tyrosine kinase inhibitor, in human cancer cells with acquired resistance to antiepidermal growth factor receptor therapy. Clin Cancer Res 2004;10: 784–93. Natale RB, Thongprasert S, Greco FA, Thomas M, Tsai CM, Sunpaweravong P, et al. Vandetanib versus erlotinib in patients with advanced non-small cell lung cancer (NSCLC) after failure of at least one prior cytotoxic chemotherapy: a randomized, double-blind phase III trial (ZEST) (abstract no. 8009). J Clin Oncol 2009;27:15s. Herbst RS, Sun Y, Korfee S, Germonpre P, Saijo N, Zhou C, et al. Vandetanib plus docetaxel versus docetaxel as second-line treatment for patients with advanced non-small cell lung cancer (NSCLC): a randomized, doubleblind phase III trial (ZODIAC) (abstract no. CRA8003). J Clin Oncol 2009;27: 18s. De Boer R, Arrieta O, Gottfried M, Blackhall FH, Raats J, Yang CH. Vandetanib plus pemetrexed versus pemetrexed as second-line therapy in patients with advanced non-small cell lung cancer (NSCLC): A randomized, double-blind phase III trial (ZEAL) (abstract no. 8010). J Clin Oncol 2009;27:15s. Miller V, Wakelee HA, Lara PN. Activity and tolerance of XL647 in NSCLC patients with acquired resistance to EGFR-TKIs: preliminary results of a phase II trial (abstract). J Clin Oncol 2008:26. Rizvi N, Kris MG, Miller VA. Activity of XL647 in clinically selected NSCLC patients (pts) enriched for the presence of EGFR mutations: results from phase 2 (abstract). J Clin Oncol 2008:26.