Efficacy of anti-PD-1 therapy in patients with melanoma brain metastases

Background: There is limited data on the efficacy of anti-programmed death 1 (PD-1) antibodies in patients (pts) with melanoma brain metastasis (BM), particularly those which are symptomatic. Method: We retrospectively assessed pts with melanoma BM treated with PD-1 antibodies, nivolumab and pembrolizumab. Clinicopathologic and treatment parameters were collected and outcomes determined for intracranial (IC) response rate (RR) using a modified RECIST criteria, with up to five IC target lesions used to determine IC response, disease control rate (DCR) and progression-free survival (PFS). Results: A total of 66 pts were identified with a median follow up of 7.0 months (range 0.8-24.5 months). A total of 68% were male and 45% BRAF V600 mutation positive. At PD-1 antibody commencement, 50% had an elevated LDH; 64% had local therapy to BM prior to commencing anti-PD1, of which 5% had surgical resection, 14% stereotactic radiosurgery (SRS), 18% whole-brain radiotherapy (WBRT), 27% had surgery and radiotherapy. Twenty-one per cent started anti-PD-1 as first line systemic therapy. No pt had prior anti-PD-1 treatment. The IC overall RR was 21 and DCR 56%. Responses occurred in 21% of pts with symptomatic BM. The median OS was 9.9 months (95% CI 6.93-17.74). Pts with symptomatic BM had shorter PFS than those without symptoms (2.7 vs 7.4 months, P = 0.035) and numerically shorter OS (5.7 vs 13.0 months, P = 0.068). Pts requiring corticosteroids also had a numerically shorter PFS (3.2 vs 7.4 months, P = 0.081) and OS (4.8 vs 13.1 months, P = 0.039). Conclusions: IC responses to anti-PD-1 antibodies occur in pts with BM, including those with symptomatic BM requiring corticosteroids. Prospective trials evaluating anti-PD-1 therapy in pts with BM are underway.