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Incidence, characteristics, and survival of patients with EGFR-mutant lung cancers with EGFR T790M at diagnosis identified in the lung cancer mutation consortium (LCMC).
Abstracts that were granted an exception in accordance with ASCO's Conflict of Interest Policy are designated with a caret symbol (^).
Background: Somatic T790M mutations are detected in 62% of EGFR-mutant lung cancers with acquired resistance to EGFR TKIs, and have rarely been identified in the tumor at diagnosis and/or within the germline DNA. Multiplexed genotyping by the LCMC permitted us to evaluate the incidence of T790M at diagnosis, co-mutations, and survival of patients with this driver. Methods: The 14 member LCMC prospectively tested tumors of patients with lung adenocarcinomas in CLIA laboratories for mutations in EGFR and 9 other genes. We assayed T790Mby Sequenom, Snapshot, or Sanger sequencing. Germline DNA was not collected. Results: In the 987 tumors tested, 209 had mutations in EGFR alone: 25 T790M (2.5%) , 157 sensitizing EGFR mutations (exon 19 del, L858R, L861Q, G719X) without T790M, 23 exon 20 ins, 4 other mutations. 13 additional cases harbored mutations in EGFR and another driver; 2 with both T790M and PIK3CA. In each of the 27 EGFR-mutant cases with T790M, a coincident EGFR mutation was detected (18 exon 19 del, 9 L858R, 1 exon 20 ins). EGFR T790M was found more often than EGFR exon 20 ins or mutations in HER2 (1.9%), BRAF (1.6%), or PIK3CA (0.7%). Patients with T790M: 77% women, 81% never smokers, median age 55 (range 38-79), stage IV at diagnosis 81%, PS 0/1 100%. Characteristics did not differ from persons with sensitizing mutations and no T790M. Median survival from the diagnosis of metastatic disease for patients with EGFR-mutant lung cancers was 3.5 yrs with T790Mand 4.0 yrs without (p=0.926). Conclusions: T790M mutations were detected at diagnosis in 3% of adenocarcinomas and always coincident with another EGFR mutation. Cases with T790M represent 13% of all cases of EGFR- mutant lung cancer. Characteristics and survival for patients with EGFR- mutant lung cancers with T790M at diagnosis were similar to individuals with sensitizing mutations and no T790M. The observed incidence of T790M exceeded that of the other actionable targets HER2, BRAF, and PIK3CA. Trials should study this unique population identified by routine multiplexed genotyping. Supported by 1RC2CA148394-01 and the National Lung Cancer Partnership. Clinical trial information: NCT01014286.
Abstracts by M. G. Kris:
Can we really treat patients older than age 70 with a chemotherapy doublet for non-small cell lung cancer (NSCLC)-Meeting: 2011 ASCO Annual Meeting | Abstract No: 7546
Clinical, pathologic, and molecular characteristics of patients with non-small cell lung cancer harboring mutations in PIK3CA.Meeting: 2011 ASCO Annual Meeting | Abstract No: 7587