Risk of dermatologic and mucosal adverse events associated with PD-1/PD-L1 inhibitors in cancer patients A meta-analysis of randomized controlled trials

Background: Programmed death 1 protein (PD-1) and programmed death-ligand 1 (PD-L1) inhibitors are promising cancer immunotherapy. Their dermatologic safety profiles are still poorly understood. The purpose of this article is to evaluate the incidence of selected dermatologic and mucosal adverse effects (AEs) and determine the risk of developing these adverse events associated with PD-1/PD-L1 inhibitors, compared with chemotherapy or ipilimumab. Methods: PubMed was searched for eligible studies (up to February 21, 2019). Only phase II and phase III randomized controlled trials (RCTs) compared with chemotherapy or ipilimumab monotherapy were included in this meta-analysis. Results: A total 11,465 patients from 18 clinical trials were included in this meta-analysis. Rash and pruritus were the most frequently reported dermatologic AE, with incidence 11.8% and 12.2% respectively. Compared with patients receiving chemotherapy, PD-1/PD-L1 inhibitor treated patients had higher risk of developing rash (RR= 1.84), pruritus (RR= 3.74) and vitiligo (RR= 9.54), and also lower risk in developing mucosal inflammation (RR= 0.26), stomatitis (RR= 0.26), and alopecia (RR= 0.03). Additionally, anti-PD1/PD-L1 drugs had similar risk of developing rash and lower risk of inducing pruritus compared to ipilimumab. In the subgroup analysis, PD-L1 inhibitor demonstrated better safety than PD-1 inhibitor in developing rash, with RR= 1.38 and RR= 2.11, respectively. Conclusion: Our meta-analysis concluded that anti PD-1/PD-L1 drugs have different dermatological and mucosal safety profile compared to conventional therapy, and differences of dermatological toxicity between PD-1 and PD-L1 inhibitor warrant further investigation.