Abstract
Treatment with immune checkpoint inhibitors has improved prognosis among patients with cutaneous melanoma, but there are still unmet medical needs in Japan, especially for mucosal melanoma and acral lentiginous melanoma (ALM) subtypes. Ipilimumab, a fully human monoclonal antibody that specifically blocks cytotoxic T-lymphocyte-associated antigen 4 and potentiates antitumor T-cell response, was approved in Japan in 2015 for the treatment of radically unresectable malignant melanoma. This postmarketing surveillance (prospective, non-interventional, multicenter, observational study) evaluated the safety (occurrence of adverse drug reactions [ADR]) and efficacy (overall survival [OS]) of ipilimumab in a real-world setting in Japan. All patients with radically unresectable malignant melanoma undergoing treatment with ipilimumab in Japan during the registration period between August 2015 and February 2017 were enrolled. In total, 547 patients were analyzed; 67.5% were 60 years old or more, 85.7% had an Eastern Cooperative Oncology Group performance status of 0-1, 50.3% had melanoma of the skin (mainly of the ALM subtype) and 73.5% had negative BRAF mutation status. Most patients had experienced recurrence and received multiple treatments. The overall incidence of ADR and serious ADR was 69.5% and 40.8%, respectively. The most common ADR and serious ADR were liver disorder, colitis and diarrhea. The most common ADR of special interest were liver-related ADR (22.5%), skin-related ADR (22.1%), gastrointestinal-related ADR (20.3%) and endocrine system-related ADR (16.3%). Most of these events had recovered or were in remission by the last evaluation. The median OS was 7.52 months (95% confidence interval, 6.47-8.74). Median OS was 6.31 and 8.44 months in patients with mucosal melanoma and melanoma of the skin; 9.43 and 3.75 months in patients with and without ADR; and 10.32 and 6.11 months in patients with and without serious ADR, respectively. Ipilimumab was tolerable and showed efficacy in improving OS for these patients.