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Introduction: Mutations in the KRAS gene are the most common driver oncogenes present in lung adenocarcinomas. We analyzed the largest multi-institutional database available containing patients with metastatic KRAS-mutant lung adenocarcinomas. Methods: The Lung Cancer Mutation Consortium (LCMC) is a multi-institutional collaboration to study the genomic characteristics of lung adenocarcinomas, treat them with genomically directed therapeutic approaches, and assess their outcomes. Since its inception in 2009, the LCMC has enrolled more than 1900 patients and has performed pretreatment, multiplexed, molecular characterization along with collecting clinical data. We evaluated the characteristics of patients with KRAS mutation in the LCMC and the association with overall survival. Results: Data from 1655 patients with metastatic lung adenocarcinomas were analyzed. Four hundred fifty (27%) patients had a KRAS mutation, 58% were female, 93% were smokers, and there was a median age of 65 years. Main KRAS subtypes were: G12C 39%; and G12D and G12V at 18% each. Among patients with KRAS mutation, G12D had a higher proportion of never-smokers (22%, p < 0.001). Patients with KRAS-mutant tumors had a trend toward shorter median survival compared to all others in the series (1.96 versus 2.22; P = 0.08) and lower 2-year survival rate (49% [95% confidence interval: 44%–54%] and 55% [95% confidence interval: 52%–58%], respectively). Conclusions: In the LCMC study, 27% of lung adenocarcinomas patients harbored a KRAS mutation and up to one-third of them had another oncogenic driver. Patients with both KRAS and STK11 mutations had a significantly inferior clinical outcome.

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In vitro, EGFR inhibition, combined with the BRAF inhibitor vemurafenib, causes synergistic cytotoxicity for BRAF V600E metastatic colorectal cancer, further augmented by irinotecan. The safety and efficacy of vemurafenib, irinotecan, and cetuximab in BRAF-mutated malignancies are not defined. In this 3+3 phase I study, patients with BRAF V600E-advanced s olid cancers received cetuximab and irinotecan with escalating doses of vemurafenib. Nineteen patients (18 with metastatic colorectal cancer and 1 with appendiceal cancer) were enrolled. Three patients experienced dose-limiting toxicities. The MTD of vemurafenib was 960 mg twice daily. Six of 17 evaluable patients (35%) achieved a radiographic response by Response Evaluation Criteria in Solid Tumors 1.1 criteria, consistent with in vivo models demonstrating tumor regressions with the triplet regimen. Median progression-free survival was 7.7 months. BRAF V600E circulating cell-free DNA (cfDNA) trends correlated with radiographic changes, and acquired mutations from cfDNA in genes reactivating MAPK signaling were observed at progression. SIGNIFICANCE: Vemurafenib, in combination with irinotecan and cetuximab, was well tolerated in patients with refractory, BRAF-mutated metastatic colorectal cancer, and both survival outcomes and response rates exceeded prior reports for vemurafenib and for irinotecan plus cetuximab in BRAF V600E metastatic colorectal cancer. In vivo models demonstrated regressions with the triplet, in contrast with vemurafenib and cetuximab alone. cfDNA predicted radiographic response and identified mutations reactivating the MAPK pathway upon progression.