Characterization of Dermatitis after PD-1/PD-L1 Inhibitor Therapy and Association with Multiple Oncologic Outcomes: A Retrospective Case-Control Study

Background: Cutaneous adverse events are common with programmed death 1 (PD-1)/programmed death ligand 1 (PD-L1) 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: To assess the nature of dermatitis after exposure to a PD-1/PD-L1 inhibitor 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%). The overall tumor response rate was 65.0% for the case patients and 17.0% for the controls (P=.0007) (odds ratio, 7.3; 95% confidence interval, 2.3-23.1). The progression-free survival and overall survival times were significantly longer for the case patients than for the controls by Kaplan-Meier analysis (P < .0001 and.0203, respectively). Limitations: The retrospective design and relatively small sample size precluded matching for all cancer types. Conclusions: Lichenoid and spongiotic dermatitis associated with PD-1/PD-L1 inhibitors could be a sign of robust immune response and improved oncologic outcomes. The value of PD-1/PD-L1erelated dermatitis in predicting cancer outcomes awaits investigation through prospective multicenter studies for specific cancer types.