Characterization of dermatitis after PD-1/PD-L1 inhibitor therapy and association with multiple oncologic outcomes: A retrospective case-control study

Abstract Background Cutaneous adverse events are common with Programmed Death (PD)-1/ PD-Ligand (L)1 inhibitors. However, the nature of the specific cutaneous adverse event of dermatitis has not been investigated across various PD-1/PD-L1 inhibitors. Oncologic outcomes potentially associated with dermatitis are not well characterized. Objective (s): To assess the nature of dermatitis after PD-1/PD-L1 inhibitor exposure and oncologic outcomes associated with dermatitis. Methods Retrospective, matched, case-control study conducted at a single academic center. Results The most common histologic patterns were lichenoid dermatitis (50%) and spongiotic dermatitis (40%). Overall tumor response rate was 65.0% for cases and 17.0% for controls (p=0.0007), odds ratio: 7.3 (95% CI 2.3-23.1). Progression Free Survival (PFS) and Overall Survival (OS) times were significantly longer for cases than controls by Kaplan-Meier analysis (p Limitations Retrospective design and relatively small sample size precluded matching on all cancer types. Conclusion Lichenoid and spongiotic dermatitis associated with PD-1/PD-L1 inhibitors could be a sign of robust immune response and improved oncologic outcomes. The predictive value of PD-1/PD-L1 related dermatitis on cancer outcomes awaits investigation through prospective multicenter studies for specific cancer types.