Survival of patients with non-small cell lung cancer having leptomeningeal metastases treated with immune checkpoint inhibitors.

INTRODUCTION: Patients with non-small cell lung cancer (NSCLC) experience leptomeningeal metastases (LM) in 3-9% of cases. Because overall survival (OS) and performance status are very poor, they are mostly excluded from clinical trials. Here, we evaluated survival of patients with NSCLC having LM treated with immune checkpoint inhibitors (ICIs). METHODS: A prospectively collected list of patients with advanced NSCLC treated with ICIs between November 2012 and July 2018 in 7 European centres was merged. All patients with LM before ICI start were selected, data were retrospectively added and patients were classified according to the National Comprehensive Cancer Network (NCCN) LM prognostic classification (good/poor). Progression-free survival (PFS) and OS on ICIs were evaluated. RESULTS: Nineteen of 1288 (1.5%) patients had LM; 73.7% had synchronous brain metastases; 73.7% had neurological symptoms at the start of ICIs and 52.6% were in the NCCN LM good prognosis group. Programmed death ligand-1 (PD-L1) expression was known for 42.1% of patients (87.5% positive). Median follow-up was 13 months from the start of ICIs, and median (95% confidence interval [CI]) PFS on ICIs was 2.0 (1.8-2.2) months. Six-month PFS rate was 21.0% and was significantly higher in the NCCN good versus poor prognostic group: 40% vs 0% (p = 0.05). Twelve-month PFS rate was 0%. Median (95% CI) OS from the start of ICIs was 3.7 (0.9-6.6) months. Six-month OS rate was 36.8%, and 12-month OS rate was 21.1%; both were not statistically significantly different for the good versus poor NCCN prognostic group (p = 0.40 and p = 0.56, respectively). CONCLUSION: Some patients with NSCLC having LM do benefit from ICI treatment; specifically, those in the NCCN LM good prognosis group can obtain a long survival.