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WHITE PAPER
The Molecular Biomarker
Revolution in Non-Small Cell
Lung Cancer
Christopher Ung, M.Sc., M.B.A., Vice President, Oncology
Therapeutic Strategy, Quintiles; Jason Hill, Ph.D., Director,
Strategic Business and Operations, Quintiles; Carrie Lee,
M.D., M.P.H., Medical Director, Oncology Therapeutic
Delivery Unit, Quintiles, Harish Dave, M.D., M.B.A., M.R.C.P.,
Vice President, Oncology Therapeutic Delivery Unit, Quintiles
Executive Summary
Recent advances in understanding the molecular basis of non-small cell lung cancer (NSCLC) –
the world’s leading cause of cancer-related mortality – have heralded a revolution in personalized
cancer medicine. The growing appreciation of the immense heterogeneity of NSCLC makes it
imperative that molecular tests are developed to allow better classification of this disease and,
in turn, therapies geared specifically towards individuals or subgroups of patients rather than
continued empiricism.
This paper reviews some of the most promising molecular pathways and targeted approaches
for NSCLC. It also discusses the critical role of diagnostics needed to support these therapeutics,
examines strategies to detect and address the emergence of resistance, and considers the clinical
implications of the current explosion of NSCLC research.
Table of Contents
2
Executive Summary
01
Introduction
03
EGFR TKIs: Erlotinib and Gefitinib
04
EGFR Monoclonal Antibodies: Cetuximab
04
Dual EGFR/HER2 Inhibition: Afatinib
05
Met Inhibition
05
EML4–ALK Inhibition: Crizotinib
06
HDAC Inhibitors: Entinostat
06
VEGF-Directed Therapies
07
Squamous Cell Carcinoma
07
Diagnostics: Essential Partners for Targeted Therapies
07
The Issue of Resistance
10
Monitoring: A New Frontier
11
Looking to the Future
12
References
14
About the Authors
17
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Introduction
Simon Cheung never thought he would have to fight for his 56th birthday. The Stage IV
adenocarcinoma in his lung, found in April 2009 as part of a routine medical exam, was
devastatingly unfair given his healthy approach to life – a non-smoker diligent with his nutrition.
Given that Simon’s adenocarcinoma progressed on erlotinib (his final option of an FDA-approved
drug) after failing two systemic chemotherapy regimens, what alternatives remained? This paper
explores the scientific energies in the search for new approaches to treat NSCLC patients such
as Simon.
Traditionally, treatment decisions for lung cancer have been based solely on histologic
considerations and stage of disease. For many years the only distinction made was between small
cell lung cancer (SCLC) (~15% of lung cancer) and NSCLC (~85%) with its three primary subdivisions
of adenocarcinoma, squamous cell carcinoma, and large cell carcinoma. Only a decade ago,
oncologists were still struggling to determine the optimal platinum-containing doublet for the
treatment of advanced/metastatic NSCLC in an effort to address the apparent plateau achieved
with conventional cytotoxic chemotherapy.1–3
Then, at the turn of the century, the concept of targeted therapy started to emerge. Clinically relevant
molecular subsets began to be identified, based on specific driver mutations that occur in genes
encoding signaling proteins crucial for cellular proliferation and survival. As this new categorization
took shape, researchers came to realize that NSCLC could in fact comprise a multitude of disparate
molecular, and hence, therapeutic subsets (Figure 1).4 Identifying the relevant molecular subtypes
and matching patients with the appropriate targeted agents is now crucial if we are to make
headway in this deadly and challenging disease.
Figure 1. Evolution of knowledge in NSCLC4
Traditional view
Squamous
Adenocarcinoma
Large
cell
2004
2009
Mutations associated with drug sensitivity
EGFR Gly719X, exon 19 deletion,
Leu858Arg, Leu861Gln
Mutations associated with primary
drug resistance
EGFR exon 20 insertions
KRAS
EGFR
Unknown
Mutations associated with acquired
drug resistance
EGFR Thr790Met, Asp761Tyr,
Leu747Ser, Thr854Ala
KRAS
Unknown
EGFR
EML4-ALK
HER2
PI3KCA
BRAF Met AKT1 MAP2K1
Adapted, with permission, from Pao W, Girard N. New driver mutations in non-small cell lung cancer. Lancet Oncol
2011;12:175–180. Copyright © 2011 Elsevier.
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3
EGFR TKIs: Erlotinib and Gefitinib
Early in the development of both erlotinib (Tarceva®) and gefitinib (Iressa®) – small-molecule
inhibitors that target the epidermal growth factor receptor (EGFR) – certain characteristics emerged
as predictive of response. These included a history of never smoking, East-Asian origin, female
gender, and adenocarcinoma histology.5 DNA sequencing of tumor samples from responding
patients led to the discovery of somatic mutations in exons 18 through 21 of the EGFR tyrosine
kinase domain.6,7 The ultimate proof that EGFR-mutant NSCLC is an entirely separate entity came
from the landmark Iressa Pan-Asia Study (IPASS), in which clinical response to front-line gefitinib
was significantly improved versus chemotherapy in patients with EGFR-mutant tumors, whereas
the exact opposite held true for EGFR wild-type tumors.8,9
In April 2010, both
ASCO and the US-based
NCCN issued official
recommendations that
EGFR testing be carried
out in patients being
considered for treatment
with an EGFR TKI.
Erlotinib, which is currently indicated as second-/third-line monotherapy in patients with locally
advanced or metastatic NSCLC, has recently also shown striking efficacy first-line in patients whose
tumors carry EGFR-activating mutations.10 The prospective Phase III OPTIMAL study (n=165) found
that erlotinib tripled the primary endpoint of progression-free survival (PFS) compared with a
standard chemotherapy combination (13.1 months versus 4.6 months) in Chinese patients with
newly diagnosed EGRF mutation-positive NSCLC.11 The safety profile of erlotinib was also superior
to that of chemotherapy. These impressive results provide strong evidence for the value of pairing
EGFR inhibitors with EGFR mutant tumors and may soon place first-line erlotinib on a similar
regulatory footing with gefitinib, which is already approved as first-line therapy – at least in
Europe and Asia – for patients with EGFR mutation-positive advanced NSCLC. In addition,
in April 2010, both ASCO (the American Society of Clinical Oncology) and the US-based NCCN
(National Comprehensive Cancer Network) issued official recommendations that EGFR testing
be carried out in patients being considered for treatment with an EGFR TKI.
Although all studies conducted so far in this setting have been in Asian populations (who have
higher rates of EGFR mutation than their Western counterparts), a confirmatory Caucasian study
with erlotinib (EURTAC) reported interim results in January 2011 that reflected the results of
OPTIMAL.12 The EURTAC study was stopped early, having met its primary endpoint of PFS.
The responses seen with targeted EGFR TKIs for patients with an activating mutation in the
EGFR gene have served to redefine our hopes and expectations about what it is possible to
achieve, at least for a subset of patients with advanced NSCLC.
EGFR Monoclonal Antibodies: Cetuximab
Combining targeted agents with chemotherapy remains an intensive area of research and clinical
study.13 The Phase III FLEX trial14 with the monoclonal antibody cetuximab (Erbitux®) is interesting
primarily for this reason, showing a small but statistically significant benefit in overall survival (OS)
in patients receiving conventional chemotherapy plus cetuximab, compared with those receiving
chemotherapy alone (11.3 versus 10.1 months, p=0.044). However, the fact that the benefit was small
necessitates an ongoing search for a predictive marker for cetuximab that might identify a more
sensitive subpopulation. In colorectal cancer, activating mutations in the KRAS gene have been
shown to be a predictive biomarker of resistance to EGFR targeted monoclonal antibodies. Although
KRAS mutations also occur frequently in NSCLC of the adenocarcinoma type, KRAS mutations are
generally mutually exclusive with activating mutations in the EGFR gene.15 More analysis needs to
be done in NSCLC to determine whether there is an association between KRAS mutation and
resistance to EGFR-targeted antibodies.
4
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Dual EGFR/HER2 Inhibition: Afatinib
Importantly, NSCLC patients who have already been treated with the EGFR inhibitors erlotinib
or gefitinib, but have developed acquired resistance to these drugs, may benefit from treatment
with a novel dual receptor inhibitor, afatinib (BIBW 2992). In the Phase III LUX-Lung 1 trial,16
585 participants with lung adenocarcinoma whose tumor progressed after chemotherapy and after
erlotinib or gefitinib, were assigned to best supportive care plus either placebo or afatinib – an
irreversible inhibitor of both EGFR and human epidermal growth factor receptor 2 (HER2). Patients
receiving afatinib saw disease progression delayed by 3.3 months versus 1.1 month (p<0.0001) and
were more likely to experience tumor shrinkage (response rate 11% versus 0.5%; p<0.01), as well as
experiencing improvements in quality of life indicators. Subgroup analysis suggested that patients
who benefited most from afatinib were those who had a prior response to their original EGFR TKI
(i.e. most likely to have an EGFR mutation). As disease progression after a favorable response
to gefitinib or erlotinib is most commonly explained by the acquisition of the resistance mutation
T790M (see page 10), afatinib appears to be effective in patients with this mutation, a hypothesis
supported by in vitro data.17
NSCLC patients who have
already been treated with
the EGFR inhibitors
erlotinib or gefitinib, but
have developed acquired
resistance to these drugs,
may benefit from treatment
with a novel dual receptor
inhibitor, afatinib.
Unfortunately, however, the results of LUX-Lung 1 showed no significant difference in the primary
endpoint of OS (10.78 months for afatinib versus 11.96 months for placebo). The lack of survival
benefit may be related to the likely high enrichment of the trial population for EGFR-mutated
patients with exceptional median survival times of around 11 months in the third-/fourth-line
setting. Such survival times are very rare in NSCLC and highlight the intrinsic good prognosis of
EGFR-mutated NSCLC patients. In addition, LUX-Lung 1 had no specific pre-selection of T790M,
which may be another contributory factor to the lack of survival benefit. A new trial investigating
the combination of afatinib with cetuximab in patients whose tumors have progressed following
erlotinib treatment is selective for T790M and is currently generating much interest.
Met Inhibition
Another highly prominent line of research in NSCLC focuses on Met (mesenchymal–epithelial
transition factor; also known as c-Met). Met is a receptor tyrosine kinase that is mutated, amplified,
or overexpressed in many cancers, including NSCLC, in which it is typically associated with a worse
prognosis. Importantly, in the past few years, it has been identified as one of the mechanisms of
acquired resistance to EGFR TKIs.18 Met is a potentially valuable target in NSCLC, as shown by the
encouraging early results seen with the novel Met inhibitor ARQ-197 when added to erlotinib.19
More recently, Met has entered center stage because of another Met inhibitor, MetMAb –
a single-armed monoclonal antibody – that has demonstrated compelling evidence of activity in
a large subset of patients with advanced NSCLC.20 A Phase II trial enrolled 128 patients who had
received one or two prior lines of therapy for advanced NSCLC but had no prior exposure to an
EGFR TKI. Participants were randomized to daily erlotinib, with either MetMAb, administered
intravenously one day every 3 weeks, or intravenous placebo given on the same schedule.
The trial was designed to compare PFS in patients with high Met expression (as shown by
immunohistochemical staining), as well as PFS in the overall trial population.
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5
Although the findings in the
Met low group are difficult
to explain, they underscore
once again how important
molecular markers have
become, and the need in
some cases for dissection
of patient populations at
a highly precise level.
The patient populations were similar and did not over-represent never-smokers or patients
with other factors associated with a high probability of an EGFR mutation (as might be expected
for patients who did not receive an EGFR inhibitor earlier in treatment). In addition, each of the two
arms were evenly split between Met-high and Met-low expression. In the population as a whole,
there were no real differences in PFS or OS to suggest a benefit from MetMAb, but the two groups
of Met-high versus Met-low expression had remarkably different results. Specifically, the patients in
the Met-high group had a PFS of 12.4 weeks in the MetMAb arm versus only 6.4 weeks in the erlotinib
plus placebo group, resulting in a hazard ratio (HR) of 0.56. There was also an OS rate benefit for
Met-high patients who received the experimental treatment, with an HR of 0.55. In marked contrast,
the Met-low population had a significantly worse PFS and OS when MetMAb was added to erlotinib.20
Although the findings in the Met-low group are difficult to explain, they underscore once again how
important molecular markers have become, and the need in some cases for dissection of patient
populations at a highly precise level. In an unselected population, these results would have shown
no discernable benefit and likely would have been abandoned. Instead, it appears likely that MetMAb
represents a valuable addition to erlotinib within a particular patient subset.
EML4–ALK Inhibition: Crizotinib
The fusion of the echinoderm microtubule-associated protein-like 4 (EML4) gene and the anaplastic
lymphoma kinase (ALK) gene in NSCLC cells was discovered in 2007, and exploitation of this as a
target has been particularly rapid. Approximately 5% of newly diagnosed NSCLC patients harbor this
mutation, typically non-smokers who do not have mutations in EGFR or the KRAS gene.15 Crizotinib
is a potent oral small-molecule inhibitor of the EML4–ALK mutation, which progressed quickly to
late-stage trials and now to the FDA for review.
As crizotinib is a prime
example of a highly targeted
drug showing impressive
early results, its advent has
sparked debate about
accelerated regulatory
approval pathways to
shorten the time to market
for such therapies.
The Phase I/II data, published in the New England Journal of Medicine in October 201021 showed an
encouraging 57% response rate in 82 mostly pre-treated patients with advanced ALK-positive disease
(confirmed by pre-screening of tumor samples from approximately 1500 patients). The drug was
also very well tolerated. Crizotinib is currently in Phase III development compared with standard of
care chemotherapy for ALK-positive patients in whom a cytotoxic regimen has previously failed, and
a Phase III trial for treatment-naïve patients is ongoing. Meanwhile, as crizotinib is a prime example
of a highly targeted drug showing impressive early results, its advent has sparked debate about
accelerated regulatory approval pathways to shorten the time to market for such therapies.22
HDAC Inhibitors: Entinostat
6
A further area that has generated significant interest is the role of inhibitors of histone deacetylase
(HDAC) in combination with other targeted agents in NSCLC. HDAC inhibitors prevent cell
multiplication by sensitizing cells to apoptosis, cell-cycle inhibition, downregulation of angiogenic
factors and proteasome inhibition. In NSCLC, studies have demonstrated that HDAC inhibitors can
prevent or delay the emergence of resistance to EGFR TKIs mediated by epithelial–mesenchymal
transition (EMT) (see page 11). The ENCORE-401 study23 was designed to test the hypothesis that
erlotinib plus the oral HDAC inhibitor entinostat is more effective than erlotinib alone in previously
treated patients with advanced NSCLC. Although the researchers were not able to demonstrate
a difference in PFS or OS between the two arms in the intention-to-treat population (n=132), the
addition of entinostat was found to significantly increase OS (9.4 months versus 5.4 months;
p=0.03) in a subset of patients with high levels of E-cadherin (as detected by immunohistochemistry).
These preliminary data suggest there may be a subpopulation of NSCLC patients for whom
entinostat may have the ability to overcome erlotinib resistance. As patients with elevated
E-cadherin represent approximately 40% of the overall NSCLC population, this is potentially
a very important finding.
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VEGF-Directed Therapies
A review of targeted therapeutic approaches in NSCLC – even if not exhaustive – would be
incomplete without mention of the vascular endothelial growth factor (VEGF) pathway, which has
long been known to play an important role in tumorigenesis and metastasis. This has been borne
out by the positive results of NSCLC trials with the anti-VEGF monoclonal antibody bevacizumab
(Avastin®) in combination with chemotherapy.24 However, bevacizumab is alone amongst
anti-angiogenic molecules in showing efficacy in this population – all of the current anti-angiogenic
small molecule inhibitors (sunitinib, sorafenib, vandetanib, axitinib, vatalanib, and pazopanib) have
so far failed to show benefit in unselected NSCLC patients. In addition, use of bevacizumab is not
targeted therapy in its true sense, as it is currently based only on patient and tumor characteristics
(such as tumor histology, location, hemoptysis, and presence of brain metastases). As the efficacy
of bevacizumab can be modest, side effects can be substantial and the cost of the drug is high,
there is a clear and urgent need to identify predictive biomarkers for VEGF-targeted therapy to
determine patient subsets most likely to benefit.
There is a clear and
urgent need to identify
predictive biomarkers for
VEGF-targeted therapy to
determine patient subsets
most likely to benefit.
Squamous Cell Carcinoma
All of the preceding content of this paper has related to adenocarcinoma, the most common
histological subtype of NSCLC, where research has been most active. However, a word about
squamous cell carcinoma – which accounts for around 25% of NSCLC – is merited. Although there
have been some recent reports of molecular subpopulations in squamous cell carcinoma – such as
those with somatic mutations in the DDR2 kinase gene25 and those with amplification of PIK3CA or
FGFR126 – there is a relative paucity of such targets identified so far and no notable success stories
with associated targeted therapies. This is clearly an area where research should be intensified if
it is to keep pace with the dramatic achievements in adenocarcinoma patients.
Diagnostics: Essential Partners for Targeted Therapies
The successful innovation of targeted therapies and the rise of personalized medicine have
generated a parallel demand – to develop accurate, reliable, timely, and reproducible diagnostic
tests for identifying eligible patients. This is particularly true in the case of EGFR, for which several
different molecular markers have been developed as potential correlates of the activity of EGFR
inhibitors. These include EGFR mutations, as determined using real-time polymerase chain reaction
(PCR), EGFR gene copy number, as measured using fluorescence in situ hybridization (FISH), and
EGFR protein expression, as measured using immunohistochemistry (IHC).9,27 Although there is
some evidence to support the premise that being positive for EGFR IHC, FISH, and an activating
mutation are all associated with a greater probability of benefitting from EGFR inhibitors,
EGFR mutation status has emerged as the strongest and most consistent predictor.28
Table 1 summarizes the techniques most commonly used for the analysis of EGFR biomarkers and
also includes details for ALK translocation and Met.
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7
Table 1. Commonly used techniques for analyzing biomarkers in NSCLC
Biomarker
Most commonly used technique
EGFR
mutations
Direct sequencing of PCR-amplified exon sequences
> May need manual macrodissection or laser capture microdissection
to ensure tumor cellularity >40%
> Commonly used FFPE tissues could cause sequencing artefacts to
be seen frequently
> Unless a classical mutation is identified, positive test results should
be viewed with caution; sample resequencing and comparison with
a normal DNA sample from the same individual are paramount
to rule out polymorphisms and artefacts
Real-time PCR-based mutation identification
> High sensitivity (detection of mutant DNA when present in as little
as 1–3% relative to wild-type)
> Compatible with DNA extracted from FFPE
> Can detect only known mutations
> Limited flexibility in assay design; commercially available kits may
detect only a subset of mutations
EGFR gene
copy number
FISH
> Routinely performed with FFPE tissue sections
> Standardization: University of Colorado EGFR FISH scoring
guidelines routinely used
EGFR protein
expression
IHC
> Semi-quantitative test based on visual inspection of the intensity
of immunostaining and the % of stained cells
> Most clinical laboratories have IHC capabilities
> Lack of standardization of handling of samples and scoring of
protein levels can lead to inter-lab inconsistency
> EGFR IHC has not been correlated to response for EGFR targeted
therapies, at least in colorectal cancer
FISH
ALK
translocations > Dual color FISH probe to detect the translocation of the ALK gene
> Proximity of EML4 and ALK gene loci on chromosome 2 leads to
risk of false-positive reads
IHC
> Detection of ALK epitopes with commercially available antibodies
can preserve morphology data of tumor cells that overexpress ALK
> Expression of fusion protein is very low and therefore detection
difficult in lung cancers, leading to high risk of false negatives; has
failed to confirm most cases positive using real-time PCR
Met
FISH
> Met amplification measured by FISH. Currently no consensus
scoring guidelines for defining amplification. Also, one of the most
commonly used probes detects a large genomic region that includes
other genes in addition to Met.
IHC
> Met IHC is used to detect total receptor protein levels
Mutation
> Direct sequencing or genotyping are the two most currently used
methods to detect Met mutations
8
Examples of commercial kit
EGFR mutation analysis in
NSCLC (Quintiles, Genzyme
Genetics)
DxS EGFR mutationdetection kit (DxS Ltd).
Applied in Phase III trials such
as IPASS and BR.21
LSI EGFR SpectrumOrange/
CEP 7 SpectrumGreen probe
(Abbott Molecular). Used in
Phase III trials such as BR.21
and ISEL
EGFR PharmDx Kit (Dako).
Used in Phase III trials such
as INTEREST and ISEL
FISH: LSI ALK Dual Color,
Break Apart Rearrangement
Probe (Abbott Molecular)
IHC: CD246, ALK protein
(clone: ALK1) (Dako)
Vysis LSI D7S486 (7q31)
Probe (Abbott Molecular)
A number of commercially
available antibodies exist
for Met
Direct Sequencing.
Sequenom OncoCarta
Panel v1.0
FFPE: formalin-fixed, paraffin-embedded; FISH: fluorescence in situ hybridization; IHC: immunohistochemistry;
PCR: polymerase chain reaction.
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As shown in Table 1, many biopharma companies have begun to partner with diagnostics
manufacturers to develop validated commercial tests. In the US these are classified either
as packaged diagnostic kits (companion diagnostics), which require FDA approval, or as
laboratory-developed tests performed centrally as a service (regulated via the Clinical Laboratory
Improvement Amendments of 1988 [CLIA]). The FDA (and other regulatory authorities such as the
European Medicines Agency [EMA]) actively encourage companies to establish drug/diagnostic
partnerships as early as possible in the development cycle of a drug and are aligning their drug
and diagnostics divisions to allow for simultaneous review.
The key challenge facing clinical oncologists globally – apart from the reliability of the various testing
methods and whether they have been approved by regulatory authorities – is the fact that as many
as eight or nine different tests may need to be done for each patient before a treatment regimen can
be selected, an issue due to escalate further as biomarker research progresses. Only a small percentage
of oncologists currently have the capability to carry out all of these screens but momentum is
increasing for this to become standard of care.
In response to this problem, some academic centers have begun to develop multiplex mutational
profiling assays to combine the search for several mutations within one test.4 In addition, as
patients with advanced disease are often diagnosed using fine-needle aspirates, researchers have
successfully demonstrated the potential of testing endobronchial ultrasound-guided transbronchial
needle aspiration (EBUS-TBNA) samples for the presence of EGFR mutations.29 Other groups have
investigated mutation testing using blood rather than tissue samples and a number of studies have
been published over the past 2 years comparing mutation detection in circulating free DNA (cfDNA)
with tumor tissue.30 cfDNA can be isolated from a plasma sample, which places a lesser burden
than a tissue biopsy on the cancer patient. Several studies have shown a good correlation between
detection of EGFR mutations between cfDNA and tumor tissue with certain existing methods,
especially if an enrichment step is done prior to mutation detection.
As many as eight or nine
different tests may need
to be done for each patient
before a treatment regimen
can be selected, an issue
due to escalate further
as biomarker research
progresses.
Another possible surrogate for tumor tissue is circulating tumor cells (CTCs). One recent study
reported 92% sensitivity in the detection of EGFR mutations in isolated circulating tumor cells,31
making this a promising avenue for investigation. However, isolation of CTCs in sufficient numbers
to perform pharmacogenetic tests is still quite challenging. As emerging CTC technologies and
platforms continue to become commercially available, the potential of this surrogate sample type
will continue to unfold.
9
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The Issue of Resistance
Despite the significant
impact of EGFR TKIs in
NSCLC therapy, the clinical
efficacy of these compounds
is undermined by both
primary and acquired
resistance.
Despite the significant impact of EGFR TKIs in NSCLC therapy, the clinical efficacy of these
compounds is undermined by both primary and acquired resistance.17,32,33 Insertion mutations in
exon 20 confer primary resistance to EGFR TKIs, as do the presence of KRAS mutations. In addition,
preclinical studies suggest that activation of parallel signaling pathways, such as the VEGF pathway,
may contribute to primary resistance. Acquired resistance usually occurs within 6–12 months of
therapy initiation, often (~50%) as a result of T790M substitution in exon 20.9 In about 15–20%
of cases, acquired resistance arises from the amplification of the Met gene, resulting in “hijacking”
of the EGFR-controlled pathway,17 while in the remaining 30% the resistance mechanism remains
ill-defined and may be multifactorial (Figure 2). Although we have focused here on resistance to
EGFR TKIs, resistance to many newer modalities, such as ALK inhibitors, has also been, or is
expected to be, reported.
Figure 2. Mechanisms of resistance to EGFR TKIs32
Resistance due to
activation of other
signaling pathways:
VEGF/VEGFR IGF-1R
Primary resistance
due to KRAS
mutations (15–30%)
Target population:
activating EGFR
mutations (15%)
Unknown resistance
mechanisms
Non-sensitive EGFR
mutations
Acquired resistance to
first-generation EGFR TKIs
Secondary EGFR
mutations T790a
Met amplification
(20%)
Unknown resistance
mechanisms
a
Indicates the T790M mutation may have been present prior to treatment.
Adapted, with permission, from Giaccone G, Wang Y. Strategies for overcoming resistance to EGFR family tyrosine
kinase inhibitors. Cancer Treat Rev 2011 Feb 28 (Epub ahead of print). Copyright © 2011 from Elsevier.
www.quintiles.com
10
As mentioned earlier, preclinical data with the irreversible dual EGFR/HER2 inhibitor afatinib
indicate that agents in this class can still inhibit EGFR-T790M. More recently, novel covalent-binding
pyrimidine-based EGFR inhibitors have been identified in a unique, mutation-specific drug screen
and have shown improved potency and selectivity against EGFR-T790M in vitro.34 Drugs that block
parallel signaling pathways or signaling molecules downstream of the EGFR, such as the insulin-like
growth factor-1 receptor (IGF-1R) and the mammalian target of rapamycin (mTOR), are also
undergoing clinical evaluation. However, as drug resistance appears to be pleomorphic, with many
mechanisms potentially coexisting in the same cell population, utilizing combinations of therapies
may be a more effective approach. As such, many agents are being evaluated in combination with
the hope that resistance mechanisms will be overcome by simultaneously silencing EGFR signals
and by blocking mechanisms of evasion.32 A thorough molecular analysis of a patient's cancer
prior to treatment can establish how it would ultimately develop resistance, allowing us to tailor
treatment with greater precision to prevent resistance. For example, cancers found to harbor a small
population of cells with pre-existing Met amplification will likely benefit from adding Met inhibitors
to initial EGFR TKI, a hypothesis currently being studied in a number of trials.
Finally, it should be mentioned that NSCLC tumors become resistant to therapies such as EGFR
TKIs not just via mutations or activation of other signaling pathways, but also via the decreased
sensitivity that results from the process of EMT.32,35 The major characteristic of EMT is the
conversion from epithelial cells to motile, invasive, and migratory mesenchymal cells, with a loss
of expression of epithelial cell markers such as E-cadherin.35 Use of HDAC inhibitors increases the
epithelial phenotype and prevents or delays the emergence of EMT-mediated resistance to EGFR
TKIs, as described earlier.
Monitoring: A New Frontier
Clinicians have so far relied on the information from a single NSCLC biopsy at the point of diagnosis
to guide therapeutic decisions. We now know the situation is not static – additional mutations may
be acquired while others may be reversed, in much the same way as viruses evolve in chronic
infectious diseases such as hepatitis and HIV. In particular, the timely detection of resistance will
ultimately depend on finding a reliable means of molecular monitoring, which ideally avoids
subjecting patients to repeated tumor biopsies, although these will be important in the short term.
Monitoring may be even more important in light of a very new observation that in patients for whom
resistance is anticipated, stopping erlotinib can result in the reversal of the acquired resistance
mutation and re-sensitization of the patient to the drug.36 A recent study has investigated harnessing
the potential of cfDNA as a means of monitoring for EGFR-T790M mutation status37 while other
researchers have pioneered the development of sophisticated CTC chip technology, a novel
microfluidic platform for isolating CTCs.31,38 This field is still in its infancy and many new
developments are expected.
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Clinicians have so far relied
on the information from
a single NSCLC biopsy at
the point of diagnosis to
guide therapeutic decisions.
We now know the situation
is not static.
11
Looking to the Future
Simon Cheung’s story illustrates many of the elements described in this paper. Following
his chance diagnosis in April 2009, Simon was treated with bevacizumab plus chemotherapy.
He responded well, with significant tumor shrinkage, but by November there was evidence of
progression. At this point he was started on second-line erlotinib, to which he had a 10-month
response and was relatively free from side effects.
In September 2010, when progression was again detected, Simon had become symptomatic.
His original needle biopsy had not provided adequate material for mutational analysis and his
oncologist now recommended a core biopsy. Mutational testing confirmed the suspected
EGFR mutation but the sample tested negative for ALK amplification and KRAS. Subsequent
referral to a specialist center allowed testing for Met (negative) and T790M, which was detected.
Simon was enrolled in the T790M-positive afatinib + cetuximab trial (mentioned on page 5) on
March 12, 2011. Before receiving this treatment his condition had deteriorated markedly with
severe pleural effusion, coughing, and dyspnea; he was essentially bedbound, unable to talk and
reliant on an oxygenator. But only 2 days into the trial he experienced a profound response with
almost complete resolution of pleural effusion. He continues to enjoy life, a notable testament
to the contributions of targeted therapy.
New NSCLC studies must
avoid testing drugs in
unselected populations.
The ability to discriminate, using molecular biomarkers, those patients best suited for specific
therapies, has revolutionized the treatment of patients with NSCLC. Whereas cytotoxic chemotherapy
results in response rates of approximately 35% when used as initial therapy, an EGFR TKI, when
applied to an appropriate patient cohort, yields response rates of nearly 80%.39 A clear message
from this is that new NSCLC studies must avoid testing drugs in unselected populations. If the
blockbuster drug trastuzumab (Herceptin®), targeting HER2-overexpressing breast cancer cells, had
been tested in a non-selective manner, it would have demonstrated a single-agent response rate of
less than 5% and thus been considered ineffective.13 Indeed, this was the fate of gefitinib, which lost
its FDA indication for across-the-board second-/third-line treatment of NSCLC after the disappointing
results of the Phase III ISEL trial, which enrolled an unselected population.40 It was only after
subsequent reanalysis of ISEL that the useful role of gefitinib in patients with activating EGFR
mutations became clear.
Today, our understanding of the multiple molecular subtypes of NSCLC is continuing to increase
exponentially. In the US, 14 academic sites recently joined forces to form the Lung Cancer Mutation
Consortium (LCMC), a collaborative effort to screen 1000 patients with adenocarcinoma of the lung
for known mutations and discover new mutations. As more and more oncology biomarkers begin to
reveal themselves, it may be that the traditional design of clinical trials has to evolve to encompass
the widening array of potential targets. The recently reported BATTLE study is a prime example of
the feasibility and potential of such an approach. Although not without its flaws, two major innovations
of this unusual Phase II trial were its operational and statistical methodologies. BATTLE pioneered
an ambitious goal of incorporating four different targeted treatment arms (requiring the cooperation
of four pharmaceutical companies) and five different biomarker classifiers within a single study, and
used an adaptive randomization design to steer NSCLC patients toward therapies likely to benefit
them.41–43 Wider use of this type of approach may help speed up clinical research, revealing positive
or negative treatment outcomes earlier and identifying useful biomarkers for later-stage studies with
greater efficiency.
12
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Meanwhile, the need for pairing targeted therapies with appropriate diagnostic tests calls for
increased – and earlier – cooperation between biopharma and diagnostics companies. In this
scenario, the involvement of a Clinical Research Organization or central laboratory as a facilitator
can have several benefits, as these organizations often have an intimate understanding of the drug
development process and significant practical experience with developing and deploying biomarker
tests in a real-world setting.
The need for pairing
targeted therapies with
appropriate diagnostic tests
calls for increased – and
earlier – cooperation
between biopharma and
diagnostics companies.
Although significant technological and logistical challenges remain, it is hoped that the integration
of molecular testing and cutting-edge targeted therapies into everyday clinical practice will not lag
too far behind the rapid pace of research in NSCLC. For patients such as Simon, the molecular
biomarker revolution in NSCLC is literally saving lives.
The advances described in this manuscript would not be possible without the courage and
strength of patients with cancer such as Simon who are willing to undergo additional biopsies.
The authors thank Simon and patients with cancer in general for their selfless contribution.
www.quintiles.com
13
References
1.
Dienstmann R, Martinez P, Felip E. Personalizing therapy with targeted agents in non-small cell
lung cancer. Oncotarget 2011; 2:165–177.
2.
Gettinger S. Targeted therapy in advanced non-small-cell lung cancer. Semin Respir Crit Care Med
2008;29:291–301.
3.
Pal SK, Figlin RA, Reckamp K. Targeted therapies for non-small cell lung cancer: an evolving
landscape. Mol Cancer Ther 2010;9:1931–1944.
4.
Pao W, Girard N. New driver mutations in non-small cell lung cancer. Lancet Oncol
2011;12:175–180.
5.
Miller VA, Kris MG, Shah N, et al. Bronchioloalveolar pathologic subtype and smoking
history predict sensitivity to gefitinib in advanced non-small-cell lung cancer. J Clin Oncol
2004;22:1103–1109.
6. Lynch TJ, Bell DW, Sordella R, 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;350:2129–2139.
7.
Paez JG, Janne PA, Lee JC, et al. EGFR mutations in lung cancer: correlation with clinical
response to gefitinib therapy. Science 2004;304:1497–1500.
8.
Mok TS, Wu YL, Thongprasert S, et al. Gefitinib or carboplatin-paclitaxel in pulmonary
adenocarcinoma. N Engl J Med 2009;361:947–957.
9. Cheng H, Xu X, Costa DB, et al. Molecular testing in lung cancer: the time is now. Curr Oncol
Rep 2010;12:335–348.
10. Lin CC, Yang JC. Optimal management of patients with NSCLC and EGFR mutations. Drugs
2011;71:79–88.
11. Zhou C, Wu Y-L, Chen G, et al. Efficacy results from the randomised phase III OPTIMAL study
comparing first-line erlotinib versus carboplatin plus gemcitabine in Chinese advanced NSCLC
patients with EGFR activating mutations. Presented at the 35th European Society for Medical
Oncology (ESMO) Congress, October 8–12, 2010, Milan, Italy.
12. http://www.roche.com/media/media_releases/med-cor-2011-01-28.htm. Early successful
readout of Tarceva study in a distinct form of lung cancer. The European Randomised Trial
of Tarceva vs. Chemotherapy (EURTAC study).
13. Janku F, Stewart DJ, Kurzrock R. Targeted therapy in NSCLC – is it becoming a reality?
Nat Rev Clin Oncol 2010;7:401–414.
14. Pirker R, Pereira JR, Szczesna A, et al. Cetuximab plus chemotherapy in patients with
advanced non-small cell lung cancer (FLEX): an open-label randomised phase III trial.
Lancet 2009;373:1525–1531.
15. Aggarwal C, Somaiah N, Simon GR. Biomarkers with predictive and prognostic function in
NSCLC: ready for prime time? J Natl Compr Canc Netw 2010;8:822–832.
16. Miller VA, Hirsh V, Cadranel J, et al. Phase IIB/III double-blind randomized trial of afatinib
(BIBW 2992, an irreversible inhibitor of EGFR/HER1 and HER2), plus best supportive care
(BSC) versus placebo plus BSC in patients with NSCLC failing 1–2 lines of chemotherapy and
erlotinib or gefitinib (LUX-Lung 1). Presented at the 35th European Society for Medical Oncology
(ESMO) Congress, October 8–12, 2010, Milan, Italy.
14
www.quintiles.com
17. Hammerman PS, Janne PA, Johnson BE. Resistance to epidermal growth factor receptor
tyrosine kinase inhibitors in non-small cell lung cancer. Clin Cancer Res 2009:15:7502–7509.
18. Bonanno L, Jirillo A, Favaretto A. Mechanisms of acquired resistance to epidermal growth factor
receptor tyrosine kinase inhibitors and new therapeutic perspectives in NSCLC. Curr Drug
Targets 2011;12:922–933.
19. Schiller JH, Akerley WL, Brugger W, et al. Results from ARQ 197-209: A global randomized
placebo-controlled phase II clinical trial of erlotinib plus ARQ 197 versus erlotinib plus
placebo in previously treated EGFR inhibitor-naive patients with locally advanced or metastatic
non-small cell lung cancer (NSCLC). J Clin Oncol 2010;28 (Suppl):18s, abstr LBA7502.
20. Spigel D, Ervin T, Ramlau R, et al. Randomized multicenter double-blind placebo-controlled
Phase II study evaluating MetMab, an antibody to Met receptor, in combination with erlotinib
in patients with advanced NSCLC. Presented at the 35th European Society for Medical Oncology
(ESMO) Congress, October 8–12, 2010, Milan, Italy.
21. Kwak EL, Bang Y-J, Camidge R, et al. Anaplastic lymphoma kinase inhibition in NSCLC.
N Engl J Med 2010;363:1693–1703.
22. Chabner BA. Early accelerated approval for highly targeted cancer drugs. N Engl J Med
2011;364: 1087–1089.
23. Jotte R, Witta S, Neubauer M, et al. Molecular analysis identifies a subset of NSCLC patients
with differential sensitivity to HDAC inhibitor/EGFR TKI treatment. Presented at the 2010
Chicago Multidisciplinary Symposium in Thoracic Oncology, December 9–11, 2010, Chicago,
IL, US.
24. Horn L, Sandler AB. Emerging data with antiangiogenic therapies in early and advanced NSCLC.
Clin Lung Cancer 2009;10 (Suppl 1):S7–S16.
25. Hammerman PS, Sos ML, Ramos AH. Mutations in the DDR2 kinase gene identify a novel
therapeutic target in squamous cell lung cancer. Cancer Discovery 2011;1:76–87.
26. Ohashi K, Pao W. A new target for therapy in squamous cell carcinoma of the lung. Cancer
Discovery 2011;1:2–3.
27. John T, Liu G, Tsao M-S. Overview of molecular testing in NSCLC: mutational analysis, gene
copy number, protein expression and other biomarkers of EGFR for the prediction of response
to tyrosine kinase inhibitors. Oncogene 2009;28:S14–S23.
28. Sholl LM, Xiao Y, Joshi V. EGFR mutation is a better predictor of response to tyrosine kinase
inhibitors in non-small cell lung carcinoma than FISH, CISH, and immunohistochemistry.
Am J Clin Pathol 2010;133:922–934.
29. Garcia-Olivé I, Monsó E, Andreo F, et al. Endobronchial ultrasound-guided transbronchial
needle aspiration for identifying EGFR mutations. Eur Respir J 2010;35:391–395.
30. Bai H, Mao L, Wang HS, et al. EGFR mutations in plasma DNA samples predict tumor response
in Chinese patients with Stage IIIB to IV NSCLC. J Clin Oncol 2009;27:2653–2659.
31. Maheswaran S, Sequist LV, Nagrath S, et al. Detection of mutations in EGFR in circulating lung
cancer cells. N Engl J Med 2008;359:366–377.
32. Giaccone G, Wang Y. Strategies for overcoming resistance to EGFR family tyrosine kinase
inhibitors. Cancer Treat Rev 2011;Feb 28 (Epub ahead of print).
www.quintiles.com
15
33. Nguyen K-SH, Kobayashi S, Costa DB. Acquired resistance to EGFR TKIs in NSCLCs dependent
on the EGFR pathway. Clin Lung Cancer 2009;10:281–289.
34. Zhou W, Ercan D, Chen L, et al. Novel mutant-selective EGFR kinase inhibitors against EGFR
T790M. Nature 2009:462:1070–1074.
35. Thomson S, Buck E, Petti F, et al. Epithelial to mesenchymal transition is a determinant
of sensitivity of NSCLC cell lines and xenografts to EGFR inhibition. Cancer Res
2005:65:9455–9462.
36. Sequist LV, Waltman BA, Dias-Santagata D, et al. Genotypic and histological evolution of lung
cancers acquiring resistance to EGFR inhibitors. Sci Transl Med 2011;3:75ra26.
37. Kuang Y, Rogers A, Yeap BY. Non-invasive detection of EGFR T790M in gefitinib or erlotinib
resistant NSCLC. Clin Cancer Res 2009;15:2630–2636.
38. Sequist LV, Nagrath S, Toner M, et al. The CTC-chip: an exciting new tool to detect circulating
tumor cells in lung cancer patients. J Thorac Oncol 2009;4:281–283.
39. Miller V, Bivona T. Clinical and molecular biomarkers in non-small-cell lung cancer
www.medscape.org/viewarticle/582340.
40. Thatcher N, Chang A, Parikh P, et al. Gefitinib plus best supportive care in previously treated
patients with refractory advanced non-small-cell lung cancer: results from a randomised,
placebo-controlled, multicentre study (Iressa Survival Evaluation in Lung Cancer). Lancet
2005;366:1527–1537.
41. Kim ES, Herbst RS, Lee JJ, et al. Phase II randomized study of biomarker-directed treatment for
non-small cell lung cancer (NSCLC): The BATTLE (Biomarker-integrated Approaches of Targeted
Therapy for Lung Cancer Elimination) clinical trial program. J Clin Oncol 2009;27:8024.
42. Kim ES, Herbst RS, Lee JJ, et al. The BATTLE trial (Biomarker-integrated Approaches of Targeted
Therapy for Lung Cancer Elimination): personalizing therapy for lung cancer. Presented at the
101st Annual Meeting of the American Association of Cancer Research, April 17–21, 2010,
Washington, DC, US.
43. Rubin EH, Anderson KM, Gause CK. The BATTLE Trial: a bold step toward improving the
efficiency of biomarker-based drug development. Cancer Discovery 2011;1:17–20.
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About the Authors
Christopher Ung, M.Sc., M.B.A.
Vice President, Oncology Therapeutic Strategy, Quintiles
Christopher Ung is responsible for leading the development and execution of Quintiles oncology
strategy, leveraging the company’s solid tumor and anatomic pathology services. He directs the
strategic development initiatives and leads the implementation of new biomarker-related
technologies such as digital pathology and tissue imaging. Mr Ung directed the set up of Quintiles
anatomic pathology laboratories in China, Scotland, and Singapore. He is also responsible for
establishing strategic biomarker-related partnerships that provide value for Quintiles drug
development clients.
Prior to joining Quintiles, Mr Ung was Chief Operating Officer for Targeted Molecular Diagnostics
and previously served as Chairman of the Pathology Business Group at Dako.
Mr Ung is an expert in personalized medicine and has engaged in numerous initiatives for
personalized medicine. He managed the development and commercialization of both the
HercepTestTM and pharmDxTM EGFR assays, the industry standards used to identify patients
for treatment with Herceptin® and Erbitux®.
Mr Ung has lectured internationally to business, medical, and drug development leaders on topics
relating to biomarker development, digital pathology, and personalized diagnostics. He has
authored several research articles and made television appearances to discuss issues relating
to personalized medicine and diagnostics.
Mr Ung graduated from Lewis and Clark College with a bachelor’s degree in chemistry and
mathematics. He earned a master’s degree from the University of California, Berkeley, and his
M.B.A. at the University of California, Los Angeles.
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17
Jason Hill, Ph.D.
Director, Strategic Business and Operations, Oncology, Quintiles
Jason Hill, Ph.D., is Director, Strategic Business and Operations, Oncology, at Quintiles. He was
formerly Director of Molecular Biology at Targeted Molecular Diagnostics (TMD), a privately held
company that specialized in the development and deployment of tissue-based biomarker assays
for oncology clinical trials, which was acquired by Quintiles in 2008.
Dr Hill joined TMD in 2004 as a molecular biologist developing biomarker assays and managing
biomarker projects. He received his Ph.D. in molecular genetics from the University of Illinois at
Chicago and did his post-doctoral studies at the Cleveland Clinic Foundation. Dr Hill developed
model systems for screening chemical libraries to identify p53-modulating compounds and also
to dissect the function of TopoIIa and b isoforms in drug response. A p53-modulating compound
that he helped characterize is currently in clinical studies. He has been an author on over a dozen
peer-reviewed publications in oncology journals, and several industry white papers.
In his current role, Dr Hill uses his experience in tissue-based biomarkers to engage clinical and
translational scientists in biopharma. This provides a window into understanding and anticipating
the biomarker needs of biopharma to support the development of targeted therapies and diagnostic
assays, and to effectively communicate Quintiles global biomarker solutions for patient testing and
drug development. He also coordinates the deployment of tissue biomarker assays in Quintiles
global laboratory network. He has authored or co-authored several industry white papers and
numerous peer-reviewed publications. Dr Hill is an inventor on a biomarker patent and several
patent applications.
Carrie Lee, M.D., M.P.H.
Medical Director, Oncology Therapeutic Delivery Unit, Quintiles
Carrie Lee is a Medical Director in the Oncology Therapeutic Delivery Unit at Quintiles. She has
served as a medical monitor on Phase I–III NSCLC studies, published numerous peer-reviewed
manuscripts in the field of thoracic oncology as well as authored and served as co-principal
investigator on numerous thoracic oncology protocols while in academia. She pursued her medical
degree from Northeastern Ohio Universities College of Medicine and completed her residency in
Internal Medicine at the University of North Carolina at Chapel Hill. She earned a Masters of Public
Health Degree at the UNC School of Public Health. Dr Lee is board certified in internal medicine,
medical oncology, and preventive medicine, and currently holds an Adjunct Assistant Professor
appointment at the University of North Carolina. She regularly provides oncology care for NSCLC
cancer patients.
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Harish Dave, M.D., M.B.A., M.R.C.P.
Vice President, Oncology Therapeutic Delivery Unit, Quintiles
Harish Dave is Global Medical Head of Hematology–Oncology and Transplantation. In this role, he
oversees a number of hematology and oncology studies at all phases of drug development, as well
as providing drug development strategy and guidance. Dr Dave is an expert in global oncology
clinical trial execution and drug development; he has extensive background in the basic science
of gene regulation, tumor immunology, as well as in clinical hematology and oncology. Dr Dave
has 15 years of academic hematology–oncology experience during which he served as a principal
investigator on multiple studies. He also served as Chairman of a National Institutes of Health
Study Section and chaired the Research and Development Committee at a major academic medical
institution. He received his medical degree from the University of Sheffield Medical School, UK, and
his residency training in the Royal Postgraduate Medical School system, University of London, UK.
He conducted basic research in gene regulation and gene therapy at the US National Institutes of
Health. He is board certified in internal medicine, medical oncology, and hematology. Previously,
Dr Dave has been Associate Professor of Medicine at George Washington University and Assistant
Chief of Hematology and Chief of Laboratory of Molecular Hematology at the Veterans Affairs
Medical Center in Washington, DC.
Special recognition to Karen Lipworth, Scientific Services, Quintiles Medical Communications,
for medical writing support.
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19
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