LAUSR

Introduction: The efficacy of immune checkpoint inhibitors (ICPi) in BRAF mutant NSCLC is unknown. Methods: Multi‐institutional retrospective chart review identified 39 patients with BRAF mutant NSCLC. The patients were divided into two groups: V600E (group A, n = 21) and non‐V600E (group B, n = 18). Programmed death ligand 1 (PD‐L1) expression, tumor mutational burden (TMB) and microsatellite instability status were assessed in 29 (74%), 11 (28%), and 12 (31%) patients, respectively. Objective response rate, progression‐free survival (PFS) with ICPi, and overall survival were analyzed. Results: High (≥50%), intermediate (1–49%), and no (<1%) PD‐L1 expression was observed in 8 of 19 (42%), 6 of 19 (32%), 5 of 19 (26%), and 5 of 10 (50%), 1 of 10 (10%), and 4 of 10 (40%) cases in groups A and B, respectively. Two tumors in group A showed high TMB (25%); none were microsatellite instability status–high. Twenty‐two patients (group A, n = 12; group B, n = 10) received ICPi. Objective response rate with ICPi was 25% and 33% in groups A and B, respectively (p = 1.0). Median PFS with ICPi was 3.7 months (95% confidence interval [CI]: 1.6–6.6), and 4.1 months (95% CI: 0.1–19.6) in groups A and B, respectively (log‐rank test = 0.81, p = 0.37). Neither BRAF mutation type nor PD‐L1 expression affected the response probability/PFS. Median overall survival was not reached (95% CI: 13–NR) and comprised 21.1 months (95% CI: 1.8–NR) for patients who were and were not exposed to ICPi, respectively (log‐rank test = 5.58, p = 0.018). Conclusions: BRAF mutant NSCLC is associated with high level of PD‐L1 expression, low/intermediate TMB and microsatellite‐stable status. ICPi have favorable activity both in BRAF V600E and BRAF non‐V600E mutant NSCLC.