INTRODUCTION: Immune therapies have dramatically changed the treatment landscape 
for melanoma in the past decade. Ipilimumab, nivolumab, and pembrolizumab have 
been approved by U.S. Food and Drug Administration for the treatment of 
metastatic melanoma sequentially. Toripalimab, a humanized IgG4 monoclonal 
antibody against programmed cell death protein-1 (PD-1), was approved by 
National Medical Product Administration in China in 2018 as second-line therapy 
for metastatic melanoma.
AREAS COVERED: This is a comprehensive review of the literature and studies of 
toripalimab in melanoma, including clinical trials and translational research.
EXPERT OPINION: Toripalimab is not inferior to pembrolizumab as a second-line 
therapy for metastatic melanoma. Prospective validated predictive markers are 
lacking. Programmed cell death ligand 1 expression and tumor mutational burden 
are two common recognized biomarkers, but the predictability of these markers 
requires additional improvement. A number of studies have confirmed that PD-1 
inhibitors, including toripalimab, are not as effective in mucosal and acral 
melanomas as in non-acral cutaneous subtype. Toripalimab in combination with 
tyrosine kinase inhibitor axitinib has shown a promising result for metastatic 
mucosal melanoma. It is crucial to explore the mechanisms underlying the varying 
biological behavior of melanoma subtypes, which may also provide clues of innate 
and acquired resistance to PD-1 blockade.