The characterization and management of immune checkpoint inhibitor–induced pruritus: A retrospective review.

e24167 Background: Immune checkpoint inhibitors (ICIs) are monoclonal antibodies widely used in cancer treatment to block inhibitory pathways and activate antitumor immunity¹. ICIs can contribute to a vast array of dermatologic immune-related adverse events (d-irAEs) 2 . Pruritus is the second most common d-irAE, occurring in 13-20% of patients 3 , however significant gaps still remain in the understanding and management of ICI-induced pruritus. This study aimed to characterize ICI-induced pruritus, describe treatment patterns, and assess its impact on adherence to immunotherapy. Methods: A retrospective review of medical records for cancer patients treated with PD-1, PD-L1, or CTLA-4 inhibitors who had an ICD-10 pruritus code (L29.X) was performed. 971 individuals were manually verified to have ICI-induced, with a median age of 71 (range, 23-101). The cohort was 59.7% male, 62.9% White, 20.0% Asian, 9.3% Hispanic or Latino, and 3.0% Black or African American. Results: Pruritus onset occurred after a median of 2 infusion cycles (IQR, 1-4) and persisted for a median of 195 days (IQR, 70-440). Combined PD-1/CTLA-4 inhibitors had a significantly earlier symptom onset compared to PD-1 inhibitor monotherapy (t(415) = 6.73, p < 0.00001). Most patients received topical corticosteroids (96.0%) and/or antihistamines (91.5%). Systemic treatments included oral corticosteroids (14.8%), gabapentinoids (5.3%), and dupilumab (1.9%). Nearly 1 in 5 patients experienced QoL impairment, affecting sleeping, eating, and showering. 49.1% had a recorded CTCAE grade 4 of 1, 23.7% were Grade 2, and 27.2% were Grade 3. Overall, 12.2% of patients paused treatment due to pruritus, and 6.3% had treatment discontinued. Grade 3 patients were 12 times more likely to experience a treatment pause than Grade 1 patients (OR 12.40; 95% CI 5.91-29.18; p < 0.00001). Conclusions: ICI-induced pruritus has the potential to impact cancer treatment via both treatment pauses and treatment cessation. Dermatology involvement was low overall (36.5%), and 40% of patients with Grade 3 pruritus were not referred to a dermatologist, representing a large treatment gap. This data suggests an underutilization of dermatology care despite the high impact of severe pruritus on ICI interruption. Improved integration with dermatology has the potential to reduce unnecessary treatment pauses and support patient care.