PD-1 inhibitors versus conventional therapies for adjuvant treatment of resected acral melanoma: A systematic review and meta-analysis.

Abstract

e21555 Background: Acral melanoma (AM) is a rare and aggressive melanoma subtype with unique characteristics in western Caucasian population, but mostly prevalent in Asian population. FDA has approved pembrolizumab and nivolumab for the adjuvant treatment of melanoma. However, its role in AM is still unclear. In US and mainland of China, high-dose interferon alfa was once approved, while in other part of the world, there was no standard treatment for adjuvant therapy of AM. Thus, we performed a meta-analysis to summarize the efficacy of anti-PD-1 monotherapy in patients with AM in adjuvant setting and derive implications for early-stage AM management. Methods: A systematic review of electronic databases was conducted to identify studies that assessed relapse-free survival (RFS) and overall survival (OS) between adjuvant PD-1 and conventional therapy (interferon (IFN) / chemotherapy) or observation alone in patients with AM. RFS was the primary endpoint, OS was the secondary endpoint. We estimated RFS/OS using the fixed-effect model. Statistical analyses in our study were carried out using Stata 12.0 (Stata Corp LP, College Station, TX, USA). Results: Five retrospective studies that totally involving 516 patients with AM were recruited, including 3 China studies and 2 non-China studies. Among them, there were 260 PD-1, 74 IFN, 178 OBS and 4 chemotherapy, respectively. Adjuvant PD-1 inhibitor achieved better efficacy than conventional therapy, showing significant improvement both in RFS (HR 0.76, 95%Cl 0.61-0.95) and OS (HR 0.57 0.37-0.88). This trend of RFS/OS benefit was observed in all subgroups, includes control treatment (OBS/IFN) or study region (China/non-China). Conclusions: Our data supports that patients with resected AM are more likely to derive benefit from adjuvant PD-1 comparing to conventional treatment or observation alone. Perspective studies are warranted to explore the role of adjuvant PD-1 in AM. [Table: see text]