Comparing the clinical efficacies of anti-PD-1 antibody monotherapy and anti-PD-1 and anti-CTLA-4 combination therapy as first-line immunotherapy in Japanese advanced acral melanoma: A retrospective, multicenter study (JAMP-neo study).
Authors: Nakamura Yasuhiro , Kiniwa Yukiko , Kato Hiroshi , Yamasaki Osamu , Maekawa Takeo , Matsushita Shigeto , Takenouchi Tatsuya , Inozume Takashi , Nakai Yasuo , Fukushima Satoshi , Saito Shintaro , Otsuka Atsushi , Fujimoto Noriki , Isei Taiki , Baba Natsuki , Matsuya Taisuke , Tanaka Ryo , Kaneko Takahide , Onishi Masazumi , Yoshikawa Shusuke 
Published: June 2021

9542 Background: Anti-PD-1 antibody monotherapy (PD1) has been commonly used for patients with advanced acral melanoma (AM). However, recent studies have demonstrated the limited clinical efficacy of PD1 in AM compared to non-acral cutaneous melanoma, particularly in nail apparatus melanoma. Although advanced AM patients are strong candidates for first-line anti-PD-1 and anti-CTLA-4 combination therapy (PD1+CTLA4), data on the clinical efficacy of PD1+CTLA4 in AM are lacking. Thus, we aimed to compare the clinical efficacies of PD1+CTLA4 and PD1 in Japanese advanced AM patients. Methods: We retrospectively reviewed the clinical records of advanced AM patients treated with PD1+CTLA4 or PD1 as first-line immunotherapy at 23 Japanese institutions. Clinical response was assessed using the Response Evaluation Criteria in Solid Tumors (RECIST) criteria. Survival was estimated using Kaplan-Meier analysis. Toxicity was assessed according to CTCAE 4.0. Results: A total of 192 patients (median age, 72 years) with advanced AM (palm and sole melanoma, 135; nail apparatus melanoma, 57) were included in the study. PD1+CTLA4 and PD1 were used as first-line immunotherapy in 39 and 153 patients, respectively. The baseline demographics and characteristics were similar between the PD1+CTLA4 and PD1 groups, except for age (median age 67.3 vs. 73.2; P = 0.005). The objective response rate (ORR) in PD1+CTLA4 was significantly higher than that of the PD1 group (38.5% vs. 16.3%; P = 0.047). The median progression-free survival (PFS) and overall survival (OS) in the PD1+CTLA4 group tended to be longer than those of the PD1 group, but the differences were not significant (median PFS 7.3 months vs. 4.5 months; P = 0.19, median OS 43.6 months vs. 18.2 months; P = 0.19). In the subgroup analysis of the palm and sole melanoma cohorts, no significant differences in ORR, PFS, and OS were observed between the PD1+CTLA4 and PD1 groups (ORR 31% vs. 20.8%; P = 0.67, median PFS 5.3 months vs. 5.9 months; P = 0.87, median OS not reached vs. 22.3 months; P = 0.66). Meanwhile, the nail apparatus melanoma cohort in the PD1+CTLA4 group exhibited significantly higher ORR, and longer PFS and OS than the PD1 group (ORR 60% vs 6.1%; P < 0.001; median PFS 19.6 months vs 3.8 months; P = 0.008, median OS 43.6 months vs 13.5 months; P = 0.049). Due to immune-related adverse events in all cohorts, the treatment cessation rate was higher in the PD1+CTLA4 group than the PD1 group (59% vs. 11.8%). Conclusions: PD1+CTLA4 was clinically more efficacious than PD 1 in advanced AM patients. Notably, advanced nail apparatus melanoma patients were strong candidates for first-line PD1+CTLA4.