Phase II study of pembrolizumab in leptomeningeal carcinomatosis.

2007Background: Approximately 5-8% of patients with cancer develop leptomeningeal carcinomatosis (LMD). Median survival of patients with LMD is approximately 4-6 weeks and there are no effective treatment options. We performed a phase II study of pembrolizumab in LMD from any solid tumor malignancy (NCT02886585). Methods: The primary endpoint is the rate of overall survival at 3 months (OS3). A Simon two-stage design was used to compare a null hypothesis OS3 of 18% against an alternative of 43%. Ten patients were to be enrolled in the first stage. If 2 or more patients were alive at 3 months, an additional 8 patients would be enrolled. If at least 6 patients among the total of 18 patients were alive at three months, then the treatment would be deemed promising in the cohort. Serial CSF, blood samples and tumor samples were collected to elucidate the genomic and transcriptional determinants of immunotherapy response in central nervous system (CNS) lesions. Results: A total of 18 patients were accrued (15 w...