Use of immune checkpoint inhibitors prolonged overall survival in a Japanese population of advanced malignant melanoma patients: Retrospective single institutional study

Although recent clinical trials have revealed that immune checkpoint inhibitors significantly improved the overall survival (OS) of patients with advanced melanoma, these previous studies comprised mainly white populations, in which superficial spreading melanoma (SSM) and lentigo maligna melanoma are the major clinical types of melanoma. In contrast, Asians manifest a distinct clinicopathological type of melanoma from that of whites and show much higher frequencies of acral lentiginous melanoma (ALM) and mucosal melanoma, which have been shown to be less susceptible to immune checkpoint inhibitors. Because no comparative studies have been published showing improvement of OS by immune checkpoint inhibitors in Asian melanoma patients, we retrospectively collected the data for 45 melanoma patients treated with checkpoint inhibitors and 24 melanoma patients treated with chemotherapy alone before immune checkpoint inhibitors became available, and compared their OS. The results showed that the patients treated with immune checkpoint inhibitors had significantly better OS than did those treated with chemotherapy alone (P < 0.0001). Improved OS was observed in both the SSM and the ALM patients. In addition, multivariate Cox regression analyses revealed that use of immune checkpoint inhibitors was associated with favorable prognosis (P = 0.0001), indicating that use of immune checkpoint inhibitors is an independent factor for favorable survival. Our study showed that immune checkpoint inhibitors may also improve the prognosis of Asian melanoma patients.