The Treatment of Pembrolizumab-Induced Pruritus with Topical Roflumilast Cream 0.3% Once Daily.

Pembrolizumab is an immune checkpoint inhibitor that is used in the treatment of various cancers. The reported mode of action of pembrolizumab is via binding to the PD-1 receptor which leads to blocking both immune-suppressing ligands, PD-L1 and PD-L2, from interacting with PD-1 to modulate the immune response. A common side effect of immune checkpoint inhibitors is pruritus, reported to occur in 14 to 47 percent of patients, which often reduces overall quality of life. This case report chronicles a patient suffering from significant pruritus and a lichenoid skin eruption after initiation of pembrolizumab treatment that was refractory to topical corticosteroid therapy, narrow band ultraviolet B light, and application of emollients. A topical phosphodiesterase-4 (PDE-4) inhibitor, roflumilast cream 0.3%, was subsequently initiated. Roflumilast is a selective inhibitor of PDE-4, approved by the United States Food and Drug Administration (FDA) in a 0.3% cream vehicle in 2022 for treatment of plaque psoriasis of any severity, and in a 0.3% foam vehicle in 2023 for treatment of seborrheic dermatitis of any severity. In 2024, roflumilast was FDA-approved in a 0.15% cream vehicle for treatment of mild-to-moderate atopic dermatitis in patients six years of age and older. In this adult patient, pruritus was improved within 48 hours after initiation of roflumilast cream 0.3% applied once daily and continued to be effective with use over time.