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Diverse EGFR Exon 20 Insertions and Co-Occurring Molecular Alterations Identified by Comprehensive Genomic Profiling of NSCLC

Open ArchivePublished:July 05, 2018DOI:https://doi.org/10.1016/j.jtho.2018.06.019

      Abstract

      Introduction

      EGFR exon 20 insertions (EGFRex20ins) comprise an uncommon subset of EGFR-activating alterations relatively insensitive to first- and second-generation EGFR tyrosine kinase inhibitors (TKIs). However, recent early clinical data suggests these patients may benefit from newer-generation EGFR-TKIs. Comprehensive genomic profiling (CGP) identifies a broad spectrum of EGFRex20ins and associated co-occurring genomic alterations (GAs) present in NSCLC.

      Methods

      Hybrid capture-based CGP was performed prospectively on 14,483 clinically annotated consecutive NSCLC specimens to a mean coverage depth of greater than 650X for 236 or 315 cancer-related genes.

      Results

      Of 14,483 NSCLC cases, CGP identified 263 (1.8%) cases with EGFRex20ins, representing 12% (263 of 2251) of cases with EGFR mutations. Sixty-four unique EGFRex20ins were identified, most commonly D770_N771>ASVDN (21%) and N771_P772>SVDNP (20%). EGFR amplification occurred in 22% (57 of 263). The most common co-occurring GAs effected tumor protein p53 (TP53) (56%), cyclin dependent kinase inhibitor 2A (CDKN2A) (22%), cyclin dependent kinase inhibitor 2B (CDKN2B) (16%), NK2 homeobox 1 (NKX2-1) (14%) and RB transcriptional corepressor 1 (RB1) (11%); co-occurring GAs in other known lung cancer drivers were rare (5%). Average tumor mutational burden was low (mean 4.3, range 0 to 40.3 mutations/Mb). Clinical outcomes to first- and second-generation EGFR TKIs were obtained for five patients and none responded.

      Conclusions

      In the largest series of EGFRex20ins NSCLC, diverse EGFRex20ins were detected in 12% of EGFR-mutant NSCLC, a higher frequency than previously reported in smaller single-institution studies. Clinical outcomes showed lack of response to EGFR TKIs. Tumor mutational burden was low, consistent with non–smoking associated NSCLC. Comprehensive sequencing revealed increased proportion and wide variety of EGFRex20ins, representing a population of patients significant enough for focused efforts on effective interventions.

      Keywords

      Introduction

      EGFR exon 19 deletions and EGFR exon 21 L858R represent the vast majority of EGFR-activating mutations, and are exquisitely sensitive to approved EGFR tyrosine kinase inhibitors (TKIs) such as erlotinib, gefitinib, and afatinib.
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      Gefitinib or carboplatin-paclitaxel in pulmonary adenocarcinoma.
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      Erlotinib versus standard chemotherapy as first-line treatment for European patients with advanced EGFR mutation-positive non-small-cell lung cancer (EURTAC): a multicentre, open-label, randomised phase 3 trial.
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      Phase III Study of afatinib or cisplatin plus pemetrexed in patients with metastatic lung adenocarcinoma with EGFR mutations.
      Less common EGFR mutations have variable sensitivity to EGFR inhibitors, although many still show clinical sensitivity to EGFR TKIs (e.g., EGFR G719X, L861Q, and S768I).
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      Clinical activity of afatinib in patients with advanced non-small-cell lung cancer harbouring uncommon EGFR mutations: a combined post-hoc analysis of LUX-Lung 2, LUX-Lung 3, and LUX-Lung 6.
      EGFR exon 20 insertions (EGFRex20ins) are a collection of EGFR driver mutations characterized by in-frame insertions that typically serve to constitutively upregulate EGFR kinase activity similar to sensitizing mutations (but are insensitive to first- and second-generation EGFR-TKIs). These alterations have previously been reported to comprise approximately 4% to 10% of all EGFR mutant lung cancers.
      • Jia Y.
      • Juarez J.
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      • et al.
      EGF816 Exerts Anticancer Effects in Non-Small Cell Lung Cancer by Irreversibly and Selectively Targeting Primary and Acquired Activating Mutations in the EGF Receptor.
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      • Nishino M.
      • et al.
      Natural history and molecular characteristics of lung cancers harboring EGFR exon 20 insertions.
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      • Nafa K.
      • Chaft J.E.
      • et al.
      EGFR exon 20 insertion mutations in lung adenocarcinomas: prevalence, molecular heterogeneity, and clinicopathologic characteristics.
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      • Martin M.
      • et al.
      Antitumor activity of osimertinib in NSCLC harboring EGFR exon 20 insertions.
      The diverse array of exon 20 insertions and the challenges associated with identifying them may lead to underestimation of their true frequency. Although EGFRex20ins usually have the same transforming ability as more common EGFR-activating mutations and are thus considered driver mutations, they are typically unresponsive to first- and second-generation EGFR TKIs due to the modified structures of their kinase domains.
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      • Juarez J.
      • Li J.
      • et al.
      EGF816 Exerts Anticancer Effects in Non-Small Cell Lung Cancer by Irreversibly and Selectively Targeting Primary and Acquired Activating Mutations in the EGF Receptor.
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      • Nishino M.
      • et al.
      Natural history and molecular characteristics of lung cancers harboring EGFR exon 20 insertions.
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      • Chaft J.E.
      • et al.
      EGFR exon 20 insertion mutations in lung adenocarcinomas: prevalence, molecular heterogeneity, and clinicopathologic characteristics.
      • Riess J.W.
      • Floch N.
      • Martin M.
      • et al.
      Antitumor activity of osimertinib in NSCLC harboring EGFR exon 20 insertions.
      Very few of these EGFRex20ins, such as A763_Y764insFQEA, have shown sensitivity to first- and second-generation EGFR TKIs.
      • Yasuda H.
      • Park E.
      • Yun C.-H.
      • et al.
      Structural, biochemical, and clinical characterization of epidermal growth factor receptor (EGFR) exon 20 insertion mutations in lung cancer.
      Several next-generation EGFR TKIs (some with pan–human epidermal growth factor receptor activity) have shown pre-clinical activity against EGFRex20ins and are in clinical development (EGF816, AP32788, osimertinib, and poziotinib).
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      • Li J.
      • et al.
      EGF816 Exerts Anticancer Effects in Non-Small Cell Lung Cancer by Irreversibly and Selectively Targeting Primary and Acquired Activating Mutations in the EGF Receptor.
      • Floc'h N.
      • Martin M.J.
      • Riess J.W.
      • et al.
      Antitumor activity of osimertinib, an irreversible mutant-selective EGFR tyrosine kinase inhibitor, in NSCLC harboring EGFR exon 20 insertions.
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      • Zhu X.
      • Huang W.-H.
      • et al.
      AP32788, a potent, selective inhibitor of EGFR and HER2 oncogenic mutants, including exon 20 insertions, in preclinical models. In Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, Louisiana.
      In particular, a strong signal of clinical activity was shown with poziotinib with an overall response rate of 64% in the first 11 patients in an early phase clinical trial.
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      • Elamin Y.Y.
      • Tan Z.
      • et al.
      Mechanisms and clinical activity of an EGFR and HER2 exon 20-selective kinase inhibitor in non-small cell lung cancer.
      However, no EGFR-TKIs are currently approved for EGFRex20ins and their diversity of structures suggests that different insertion events may have divergent responsiveness to various EGFR TKIs. Thus, identifying the full array and scope of EGFRex20ins is of paramount importance.
      Studies examining EGFRex20ins have generally been limited to cases from single institutions. Certain next-generation sequencing approaches such as comprehensive genomic profiling (CGP) permit sequencing of the entire EGFR gene to broadly assess for diverse EGFRex20ins and co-existing genomic alterations (GAs) that may be relevant to the pathogenesis of EGFRex20ins-positive NSCLC. In addition to characterizing the clinical and pathologic characteristics of EGFRex20ins-positive NSCLC from a large dataset with molecular testing performed in the course of clinical care from multiple institutions, the purpose of this study was to assess the frequency and diversity of EGFRex20ins in NSCLC by their pattern of sequence alterations and co-occurring GAs, which may impact the development of targeted treatments for these patients.

      Methods

      DNA was extracted from 40-μm formalin-fixed paraffin-embedded sections. EGFRex20ins and co-occurring GAs were identified by hybrid capture-based CGP performed during the course of clinical care on 14,483 consecutive NSCLC specimens to a mean coverage depth of greater than 650X for 236 (version 1, July 2012 to August 2014) or 315 (version 2, August 2014 to June 2016) cancer-related genes plus selected introns from 19 or 28 genes frequently rearranged in cancer. EGFR amplification was defined as estimated copy number greater than 6 copies.
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      • et al.
      Development and validation of a clinical cancer genomic profiling test based on massively parallel DNA sequencing.
      Clinical data such as age, sex, stage, and histologic subtype were abstracted from the accompanying pathology report submitted by the ordering physician. Treatment outcomes from these patients were included where available. Testing was performed in a Clinical Laboratory Improvement Amendments–certified, College of American Pathologists–accredited reference laboratory (Foundation Medicine, Inc., Cambridge, Massachusetts). Patient samples were evaluated for GAs, including base-pair substitutions, insertions/deletions (indels), copy number alterations, and rearrangements, as described previously. Tumor mutational burden (TMB) was characterized as the number of somatic base substitution or indel alterations per megabase (Mb) per previously described methods.
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      • Connelly C.F.
      • Fabrizio D.
      • et al.
      Analysis of 100,000 human cancer genomes reveals the landscape of tumor mutational burden.
      Approval for this study, including a waiver of informed consent and a Health Insurance Portability and Accountability Act waiver of authorization, was obtained from the Western Institutional Review Board (Protocol No. 20152817).

      Results

      CGP performed on 14,483 NSCLC cases in the course of clinical care identified 2251 cases with EGFR mutations; 263 of these cases were EGFRex20ins, representing 12% of all EGFR-mutant NSCLC and 1.8% of all NSCLC cases tested. EGFRex20ins were the third most common type of EGFR mutation detected following EGFR exon 19 deletions (47%) and EGFR L858R (32%). Other less common EGFR mutations detected in this large case series include G719X (4%), L861Q (2%), S768I (1%), and cases with compound EGFR-activating mutations (2%) (Fig. 1).
      Figure thumbnail gr1
      Figure 1Frequency and distribution of 2251 EGFR mutations in NSCLC detected by comprehensive genomic profiling. Each alteration is shown as: mutation, number of cases, frequency.
      Clinical and pathologic characteristics were available for all of the 263 patients with EGFRex20ins as summarized in Table 1. The large majority of cases EGFRex20ins were identified in lung adenocarcinoma (90%, 237 of 263), followed by NSCLC not otherwise specified (NOS) (9.1%, 24 of 263), and sarcomatoid histology (0.7%, 2 of 263). The median age for EGFRex20-positive cases was 63 years, and 62% of patients were female. Of the 263 patients with EGFRex20ins-positive NSCLC, treatment outcomes were available for 11 patients. Five of those patients received either first- or second-generation EGFR TKIs, with none of the five patients showing a response to treatment and median time to progression of only 3.5 months (Supplementary Table 1). The remaining six patients did not receive EGFR-targeted therapy.
      Table 1Histologic and Clinical Characteristics of NSCLC Patients With Tumors Harboring EGFR Exon 20 Insertions
      Histologic SubtypeAllAdenocarcinomaNSCLC NOSSquamous/ AdenosquamousSarcomatoid
      Total cases, N14,48310,272 (71%)2197 (15%)1942 (13%)122 (0.8%)
      Patients with EGFR exon 20 Insertions, n (%)263237 (90.1%)24 (9.2%)02 (0.7%)
      Median age, y (range)63 (14-90)63 (14-90)71 (44-87)50.5 (45-56)
      Sex, n
       Male10089101
       Female163148141
      NOS, not otherwise specified.
      Sixty-four unique EGFRex20ins were identified, most commonly D770_N771>ASVDN (21%), N771_P772>SVDNP (20%), and N771_H773dupNPH (8%); 6% harbored EGFR A763_Y764insFQEA, an EGFRex20ins with pre-clinical and clinical evidence showing sensitivity to first- and second-generation EGFR-TKIs (Figs. 2 and 3). Putative co-occurring driver alterations in genes including EGFR (ex19del and L858R), erb-b2 receptor tyrosine kinase 2 (HER2), hepatocyte growth factor receptor gene (MET), and KRAS mutations tended to be mutually exclusive from EGFRex20ins, occurring only in 5% (12 of 263) of cases, and no co-occurring ALK receptor tyrosine kinase (ALK), ROS1, or ret proto-oncogene (RET) fusions or BRAF mutations were identified. Among EGFRex20ins cases, EGFR amplification occurred in 22% (57 of 263). Three cases with EGFRex20ins harbored co-occurring T790M, including two cases with A763_Y764insFQEA, which. The most common co-occurring alterations affected tumor protein p53 (TP53) (56%), cyclin dependent kinase inhibitor 2A (CDKN2A) (22%), cyclin dependent kinase inhibitor 2B (CDKN2B) (16%), NK2 homeobox 1 (NKX2-1) (14%), and RB transcriptional corepressor 1 (RB1) (11%) (Fig. 4). Co-occurring alterations did not substantially differ between EGFRex20ins and canonical EGFR mutations (EGFR exon 19 deletion and EGFR L858R) that were negative for the most common acquired EGFR TKI resistance mutation, EGFR T790M (Table 2, Fig. 4). Average TMB was low (mean 4.3, median 3.6, range 0 to 40.3 mutations/Mb) in EGFRex20ins cases — comparable with TMB in EGFR exon 19del and EGFR L858R and lower than EGFR-wild-type (WT) NSCLC (Table 2).
      Figure thumbnail gr2
      Figure 2Schematic of genomic positions of EGFR exon 20 insertions detected by comprehensive genomic profiling. EGFR amino acid positions are indicated.
      Figure thumbnail gr3
      Figure 3Frequency of unique EGFR exon 20 insertions detected by comprehensive genomic profiling. Each alteration is shown as: insertion (alternative nomenclature), number of cases, frequency.
      Figure thumbnail gr4
      Figure 4(A) Co-occurring genomic alterations with a frequency greater than 5% in NSCLC harboring EGFR exon 20 insertions. (B) Longtail of frequently co-altered genes in NSCLC with EGFRex20ins L858R, ex19del. Only cases without co-occurring T790M mutation are shown: EGFR ex20ins (n = 260), L858R (n = 542), ex19del (n = 776). Dark shading on the EGFR bars indicate co-occurring EGFR amplification.
      Table 2Comparison of Molecular, Pathologic and Clinical Characteristics of EGFR-WT, EGFR-mutant (E19del/L858R positive/T790M negative) and EGFR ex20ins NSCLC
      CharacteristicEGFR-WT NSCLCEGFR-Mutant NSCLC (E19del and L858R – T790M neg)EGFR ex20ins NSCLCp Value (EGFR-WT vs. EGFR ex20ins)p Value (EGFR-Mutant E19del and L858R vs. ex20ins)p Value (EGFR-WT vs. EGFR-Mutant E19del and L858R – T790M neg)
      Total cases, N12,5511318260
      Median age, y (range)65 (6-99)65 (25-95)63 (14-90)0.00070.020.07
      Sex, F/M (%F)6246/6304 (50)888/430 (67)161/99 (62)<0.00010.089<0.0001
      Histologic subtype
       Adenocarcinoma8572 (68)1,149 (87)235 (90)<0.00010.15<0.0001
       Squamous/adenosquamous1835 (15)50 (3.8)0
       NSCLC-NOS2027 (16)115 (8.7)23 (8.8)
       Sarcomatoid117 (0.9)4 (0.3)2 (0.8)
      Frequency of co-occurring genomic alterations
       Concurrent EGFR copy number gain355 (2.8)311 (24)57 (22)<0.00010.63<0.0001
       Concurrent TP53 alteration7,748 (62)844 (64)146 (56)0.07730.01630.107
       Concurrent RB1 alteration771 (6.1)133 (10)28 (11)0.00350.7413<0.0001
       Concurrent CDKN2A/2B alteration3,222 (26)317 (24)57 (22)0.19390.52320.2113
       TMB (mutations per MB) median8.13.63.6<0.00010.31<0.0001
       TMB low (<5)3785 (30)832 (63)179 (69)<0.01NS<0.01
       TMB intermediate low (5-10)3470 (28)400 (30)69 (27)<0.01NS<0.01
       TMB intermediate high (10-20)3325 (26)82 (6.2)10 (3.8)<0.01NS<0.01
       TMB high (>20)1971 (16)4 (0.3)2 (0.8)NSNSNS
      Values are represented as n (%) unless otherwise specified.
      Mann Whitney test for age. Chi-square tests (2-sided, alpha <0.01) used for sex, mutation data, histology (adenocarcinoma vs. all others). TMB by category: 2-way analysis of variance, Bonferroni post-test for significance. WT, wild-type; NOS, not otherwise specified; TMB, tumor mutational burden; TP53, tumor protein p53; CDKN2A/2B, cyclin dependent kinase inhibitor 2A/2B.

      Discussion

      Herein we present the largest known dataset of EGFRex20ins NSCLC, wherein 64 unique EGFRex20ins sequence alterations are identified, reflecting the diversity of these EGFR driver mutations, which comprise 12% of EGFR-mutant NSCLC and 1.8% of all NSCLC in our series. With approximately 222,000 newly diagnosed lung cancer cases annually in the United States alone, this corresponds to approximately 3000 newly diagnosed EGFRex20ins cases per year in the United States.
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      Kinetic analysis of epidermal growth factor receptor somatic mutant proteins shows increased sensitivity to the epidermal growth factor receptor tyrosine kinase inhibitor.
      EGFRex20ins were detected in 12% of EGFR-mutant NSCLC cases, which is higher than previously reported in smaller single-institution series (∼4% to 10% frequency). Prior records of molecular testing were not available for the majority of cases. Several reasons may explain the higher frequency of EGFRex20ins detected. This may reflect referral bias with enrichment for lung cancers from never-smoking patients. However, for other common EGFR alterations, frequencies detected were comparable to those reported in the literature (15.5% of all NSCLC cases). Thus, the higher frequency of EGFRex20ins is likely rather due to advancement of sequencing technology and improved detection of these alterations at lower mutant allele frequency by next-generation sequencing. Mutation-specific assays in some previous studies also likely underestimate the number of EGFRex20ins given the diversity of EGFRex20ins we detected by next-generation sequencing.
      A previous study of 27 cases at a single institution described 13 unique EGFRex20ins variants.
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      Natural history and molecular characteristics of lung cancers harboring EGFR exon 20 insertions.
      The dataset herein reports 263 cases including 64 unique EGFRex20ins variants with concomitant molecular alterations and TMB, with a comparison of these co-occurring alterations to a large dataset of EGFR-WT and canonical EGFR-mutant NSCLC.
      Sensitivity of the EGFR L858R and exon 19 deletions to EGFR TKIs is mediated by enhanced intrinsic affinity for EGFR TKI versus substrate adenosine triphosphate. Structural modeling and binding affinity studies of representative EGFRex20ins showed that first-generation EGFR TKI binding affinity is similar to that of WT EGFR.
      • Yasuda H.
      • Park E.
      • Yun C.-H.
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      Structural, biochemical, and clinical characterization of epidermal growth factor receptor (EGFR) exon 20 insertion mutations in lung cancer.
      Identifying the spectrum of EGFRex20ins where next-generation EGFR TKI can fit into a sterically hindered EGFR exon 20 binding pocket is critical to showing anti-tumor activity and improving clinical outcomes in NSCLC patients harboring diverse EGFRex20ins.
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      Structural, biochemical, and clinical characterization of epidermal growth factor receptor (EGFR) exon 20 insertion mutations in lung cancer.
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      The majority of EGFRex20ins were detected in lung adenocarcinoma, although they were also found in a limited number of lung cancers with sarcomatoid histology. In this retrospective series, these insertions were detected at a higher frequency than reported in smaller series suggesting that EGFRex20ins are more prevalent than previously reported. Although this dataset represents patients who were selected specifically by their physician to be tested for analysis, which may not represent a random cross-section of NSCLC, the higher frequency of EGFRex20ins reported could be due in part to comprehensive sequencing of EGFR compared to limitations of noncomprehensive assays performed in prior studies. Nevertheless, EGFRex20ins were the third most common EGFR-activating mutation following exon19del and L858R, and occur at approximately the same frequency as ROS1 gene fusions (∼1% in our dataset; data not shown) and BRAF V600E mutations in NSCLC (∼2% in our dataset; data not shown) where targeted therapies are approved with high rates of response and lengthy progression-free survival.
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      Available treatment outcomes showed lack of response to first- and second-generation EGFR TKIs such as erlotinib, gefitinib, and afatinib, consistent with other series, and highlighting the need for new strategies to target EGFRex20ins.
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      The EGFR A763_Y764insFQEA insertion, for which sensitivity to first- and second-generation EGFR TKIs has been described, only comprised 6% of all EGFRex20ins in our series (thus representing less than 1% of all EGFR mutations). Although we detected more than 60 EGFRex20ins, the most frequently occurring (D770_N771>ASVDN, N771_P772>SVDNP, and N771_H773dupNPH) represent approximately 50% of all detected EGFRex20ins in this series (Fig. 3). Studies of newer-generation EGFR TKIs showing pre-clinical and clinical efficacy against these particular EGFRex20ins would thus impact the greatest number of patients. More recently, poziotinib has shown robust pre-clinical and clinical activity; a confirmed response rate of 64% in EGFRex20ins NSCLC was noted in a phase 2 trial, albeit in a limited number of patients.
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      Poziotinib, due to its small size, can circumvent steric changes resulting from the exon 20 insertion to more effectively bind to mutant EGFR. Further understanding the spectrum of EGFRex20ins is important, as it is likely that among the 64 unique insertions we detected, there will be differential sensitivity to poziotinib and similar drugs due to the size and configuration of the drug-binding pocket based on the specific EGFRex20ins variant.
      The most common genomic alterations co-occurring with EGFRex20ins were tumor suppressor (e.g., TP53 and RB1) and cell cycle alterations (e.g., CDKN2A/2B). These occurred at comparable frequency in NSCLCs samples with EGFR exon 19del and EGFR L585R without EGFR T790M (Table 2, Fig. 4). Because EGFR T790M is the most common acquired resistance mutation to first- and second-generation EGFR TKIs, these were excluded for this comparison to control as best as possible for additional genomic aberrations resulting from acquired EGFR TKI resistance. As is typical of other oncogenic drivers, the vast majority of EGFRex20ins were mutually exclusive of other putative oncogenic drivers in NSCLC such as canonical EGFR, KRAS, BRAF, MET, and HER2 mutations, MET amplification, and ALK receptor tyrosine kinase (ALK), ROS1 and ret proto-oncogene (RET) fusions.
      EGFR amplification was detected in 22% of EGFRex20ins-positive NSCLCs, which is comparable to other EGFR mutations in our dataset when cases with co-occurring T790M are excluded (e.g., EGFR ex19del 23% and L858R 25%) and higher than EGFR-WT NSCLC (Fig. 4, Table 2), as noted in other studies in EGFR-mutant NSCLC.
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      Small series have described activity of the addition of cetuximab to EGFR TKIs in EGFRex20ins NSCLC.
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      Another important aspect of study is analysis of TMB, which has not been previously reported for EGFRex20ins. Immune checkpoint inhibition with programmed death 1 (PD-1) and programmed death ligand 1 (PD-L1) antibodies has revolutionized the treatment of NSCLC and improved survival outcomes for many lung cancer patients.
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      TMB measured by CGP is comparable to measurements by whole exome sequencing and is typically higher in smoking-associated lung cancer due to tobacco carcinogenesis.
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      Our study shows comparable TMB in EGFRex20ins cases to classic (exon 19 del or L858R) EGFR-mutant NSCLC that is lower than EGFR-WT NSCLC (Table 2). Less than 4% (10 of 263) of EGFRex20ins-positive cases analyzed had intermediate-high (10 to 20 mutations/Mb) TMB, and only 0.7% (2 of 263) cases had high (>20 mutations/Mb) TMB (Table 2). Overall, low TMB suggests comparable lack of benefit to single-agent PD-1/PD-L1 antibodies in EGFRex20ins NSCLC as in NSCLC harboring more common EGFR mutations.
      This study represents the largest series of EGFRex20ins with more than 60 unique EGFRex20ins detected. With next-generation EGFR TKIs showing potential activity in EGFRex20ins-positive NSCLC, identifying patients with these molecular aberrations is paramount.
      • Jia Y.
      • Juarez J.
      • Li J.
      • et al.
      EGF816 Exerts Anticancer Effects in Non-Small Cell Lung Cancer by Irreversibly and Selectively Targeting Primary and Acquired Activating Mutations in the EGF Receptor.
      • Riess J.W.
      • Floch N.
      • Martin M.
      • et al.
      Antitumor activity of osimertinib in NSCLC harboring EGFR exon 20 insertions.
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      • Zhu X.
      • Huang W.-H.
      • et al.
      AP32788, a potent, selective inhibitor of EGFR and HER2 oncogenic mutants, including exon 20 insertions, in preclinical models. In Proceedings: AACR 107th Annual Meeting 2016; April 16-20, 2016; New Orleans, Louisiana.
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      • Camidge D.R.
      • et al.
      Continued use of afatinib with the addition of cetuximab after progression on afatinib in patients with EGFR mutation-positive non-small-cell lung cancer and acquired resistance to gefitinib or erlotinib.
      In light of newly available combination trials and clinical development of fourth-generation EGFR TKIs targeting EGFRex20ins, CGP to detect diverse EGFRex20ins in NSCLC is warranted.

      Acknowledgments

      This work was supported by a Paul Calabresi Career Development Award in Clinical Oncology National Institutes of Health grant 5 K12 CA 138464 (J.W.R.) and the Bonnie J. Addario Lung Cancer Foundation and Van Auken Private Foundation Announce Young Innovators Team Award (J.W.R).

      Supplementary Data

      References

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