26PA combination of resistance mechanisms is frequent in non-small cell lung cancer (NSCLC) that progressed to EGFR tyrosine kinase inhibitors (TKIs)

Abstract Background Despite a primary benefit, almost all patients (pts) develop acquired resistance to EGFR TKIs. Some mechanisms were related to the selective pressure of the different generations (G) EGFR TKIs, but the complete alteration profile at resistance remains to be elucidated. Methods Metastatic NSCLC pts who performed a tissue and plasma biopsy at EGFR TKI progression, and optionally before, were identified from the prospective MATCH-R trial (NCT02517892). Targeted next-generation sequencing (NGS, 74 to 82 genes), comparative genomic hybridization (CGH), whole-exome sequencing (WES), and RNA sequencing (RNA-Seq) were performed on the tissue. All molecular oncogenic alterations were classified as definitive/potential resistance mechanism or concomitant genetic alterations using OncoKB and Cancer Genome Interpreter. Results Among 62 pts included, tissue analysis at TKI progression was successful with NGS (94%), CGH (76%) and WES+RNA-Seq (53%). In the post 1st-2nd G EGFR TKI cohort (31 pts) the most frequent resistance alteration was p.T790M (n = 23, 74%). EGFR amplification (amp) was found in 7 (23%) pts and off-target mutations (mut) at resistance in 9 (29%, 2 KRAS, 2 JAK2, 1 PIK3CA, and 1 MET). Median PFS to EGFR TKI was 17 months (mo) for the pts with p.T790M as the only resistance mechanism vs 8 mo for the other resistance profiles (HR 2.42 [95% CI, 1.04-5.65]; p = 0.028). In the post 3rd G cohort (31 pts), acquired resistance alterations were mostly on-target (n = 12, 39%): 9 p.C797S, 2 p.L718Q and 1 EGFR amp. Off-target resistance alterations were found in 11 (35%) tumors: 5 fusions involving oncogenes (16%, RET, BRAF, ALK, and FGFR3), 2 BRAF p.V600E (6%), then MET amp, HER2 amp, KRAS mut, and PIK3CA mut in 1 pts (3%). p.T790M loss (54%) was associated with a shorter time to osimertinib discontinuation vs maintained (median 13 vs 22 mo; HR 2.16 (95% CI, 1.00-4.73); p = 0.046). More than one resistance mechanism was found in 12 (39%) and 14 (45%) pts in the post 1st-2nd and 3rd G cohort, respectively. Conclusions Genetic alteration landscape at EGFR TKIs progression is complex and heterogeneous since more than one resistance alteration was recognized in 42% of pts. Combination strategy might be needed. Legal entity responsible for the study Gustave Roussy, Cancer Campus. Funding Gustave Roussy, Cancer Campus. Disclosure Y. Loriot: Honoraria (self): Roche, MSD, Astellas, Janssen, AstraZeneca, BMS, Seattle Genetics, Sanofi, Clovis, Pfizer; Honoraria (institution): Roche, MSD, Astellas, Janssen, AstraZeneca, BMS, Seattle Genetics, Sanofi, Clovis, Incyte, Pfizer; Research grant / Funding (institution): Roche, MSD, Sanofi; Travel / Accommodation / Expenses: Roche, MSD, Janssen, AstraZeneca, Seattle Genetics; Licensing / Royalties: Pending patent (USA 62/455211, Europe 17209098.7). D. Planchard: Advisory / Consultancy: AstraZeneca, Bristol-Myers Squibb, Boehringer Ingelheim, Celgene, Daiichi Sankyo, Eli Lilly, Merck, MedImmune, Novartis, Pfizer, prIME Oncology, Peer CME, Roche; Honoraria (self): AstraZeneca, Bristol-Myers Squibb, Boehringer Ingelheim, Celgene, Eli Lilly, Merck, Novartis, Pfizer, prIME Oncology, Peer CME, Roche; Research grant / Funding (institution): AstraZeneca, Bristol-Myers Squibb, AbbVie, Boehringer Ingelheim, Eli Lilly, Merck, Novartis, Pfizer, Roche, MedImmune, Sanofi-Aventis, Taiho Pharma, Novocure, Daiichi Sankyo; Travel / Accommodation / Expenses: AstraZeneca, Bristol-Myers Squibb, Boehringer Ingelheim , Roche, Merck, Novartis, prIME Oncology, Pfizer. S. Michiels: Advisory / Consultancy, Punctual statistical advice : IDDI Belgium, Janssen Cilag France; Advisory / Consultancy, Data and Safety Monitoring Member: Hexal, JJ Principal/sub-Investigator of Clinical Trials for AbbVie, Agios Pharmaceuticals, Amgen, Argen-X; Research grant / Funding (institution): AstraZeneca, BMS, Boehringer Ingelheim, Janssen-Cilag, Merck, Novartis, Pfizer, Roche, Sanofi; Non-remunerated activity/ies: AstraZeneca, Bayer, BMS, Boehringer Ingelheim, Johnson & Johnson, Lilly, MedImmune, Merck, NH TherAGuiX, Pfizer, Roche. J-C. Soria: Advisory / Consultancy: AstraZeneca, Astex, Clovis, GSK, GamaMabs, Lilly, MSD, Mission Therapeutics, Merus, Pfizer, PharmaMar, Pierre Fabre, Roche/Genentech, Sanofi, Servier, Symphogen, and Takeda; Full / Part-time employment: AstraZeneca; Shareholder / Stockholder / Stock options: AstraZeneca and Gritstone. F. Andre: Research grant / Funding (institution): NVS, AZ, Roche, Daiichi, Lilly, Pfizer. G. Vassal: Advisory / Consultancy, Non-remunerated activity/ies: AstraZeneca, Bayer, BMS, Celgene, Incyte, Ipsen, Lilly, MSD, Merck, Pierre-Fabre, Novartis, Pfizer, Roche/Genentech, Servier, Takeda. B. Besse: Research grant / Funding (institution): AbbVie, Amgen, AstraZeneca, Biogen, Blueprint Medicines, BMS, Celgene, Eli Lilly, GSK, Ignyta, Ipsen, Merck KGaA, MSD, Nektar, Onxeo, Pfizer, PharmaMar, Sanofi, Spectrum Pharmaceuticals, Takeda, Tiziana Pharma. All other authors have declared no conflicts of interest.