Phase 2 Study of Dabrafenib Plus Trametinib in Patients With BRAF V600E-Mutant Metastatic NSCLC

Introduction: Dabrafenib plus trametinib was found to have robust antitumor activity in patients with BRAF V600Emutant metastatic NSCLC (mNSCLC). We report updated survival analysis of a phase 2 study (NCT01336634) with a minimum of 5-year follow-up and updated genomic data. Methods: Pretreated (cohort B) and treatment-naive (cohort C) patients with BRAF V600E-mutant mNSCLC received dabrafenib 150 mg twice daily and trametinib 2 mg once daily. The primary end point was investigator-assessed overall response rate per Response Evaluation Criteria in Solid Tumors version 1.1. Secondary end points were duration of response, progression-free survival, overall survival, and safety. Results: At data cutoff, for cohorts B (57 patients) and C (36 patients), the median follow-up was 16.6 (range: 0.5- 78.5) and 16.3 (range: 0.4-80) months, overall response rate (95% confidence interval [CI]) was 68.4% (54.8-80.1) and 63.9% (46.2-79.2), median progression-free survival (95% CI) was 10.2 (6.9-16.7) and 10.8 (7.0-14.5) months, and median overall survival (95% CI) was 18.2 (14.3-28.6) and 17.3 (12.3-40.2) months, respectively. The 4-and 5 year survival rates were 26% and 19% in pretreated patients and 34% and 22% in treatment-naive patients, respectively. A total of 17 patients (18%) were still alive. The most frequent adverse event was pyrexia (56%). Exploratory genomic analysis indicated that the presence of coexisting genomic alterations might influence clinical outcomes in these patients; however, these results require further investigation. Conclusions: Dabrafenib plus trametinib therapy was found to have substantial and durable clinical benefit, with a manageable safety profile, in patients with BRAF V600Emutant mNSCLC, regardless of previous treatment. (c) 2021 International Association for the Study of Lung Cancer. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http:// creativecommons.org/licenses/by-nc-nd/4.0/)