Analyzing the relationship between the efficacy of first-line immune checkpoint inhibitors and cumulative sun damage in Japanese patients with advanced BRAF wild-type nonacral cutaneous melanoma: A retrospective real-world, multicenter study

Abstract

Background: Efficacy of anti-PD-1 antibody monotherapy (PD1) or anti-PD-1 plus anti-CTLA-4 combination therapy (PD1 +CTLA4) for melanoma is affected by its clinical subtype. The amount of tumor mutation burden (TMB) caused by cumulative sun damage (CSD) is occasionally used to explain this; however, their relationship in Japanese nonacral cutaneous melanoma (NACM) is still unclear.

Objective: To analyze the ICI efficacy and its relationship with CSD of the primary lesion in Japanese patients with NACM.

Methods: Japanese patients with advanced BRAF wild-type NACM who received first-line ICIs were recruited. Objective response rate (ORR), progression-free survival (PFS), and overall survival (OS), and the degree of solar elastosis (SE) were evaluated.

Results: A total of 146 patients (PD1 group 113 and PD1 +CTLA4 group 33) were included. No significant differences in ORR were observed between the PD1 and PD1 +CTLA4 groups (35 % vs. 36 %; P = 0.67) or PFS and OS (median PFS 6.1 months vs. 8.5 months; P = 0.46, median OS 28.1 months vs. not reached; P = 0.59). Multivariate survival analysis revealed that PD1 +CTLA4 did not prolong the PFS and OS. The SE score had no effect on either PFS or OS.

Conclusions: ICI efficacy was not as high as those reported in Western countries, and PD1 +CTLA4 did not present better clinical efficacy compared to PD1. Indicators of CSD did not serve as a predictor for clinical advantage. These findings may partially support the theory that ICI efficacy is affected by CSD; however, other unrecognized factors may also exist.

Keywords: Anti-CTLA-4 antibody; Anti-PD-1 antibody; Cumulative sun damage; Melanoma; Nonacral cutaneous melanoma (NACM); Solar elastosis.