Treatment and impact on immunotherapy
Table 4 summarizes the ICI classes, treatments for rash, impact on immunotherapy, and response to dermatologic therapy or interruption of immunotherapy according to the grade of cutaneous irAE.
The combined use of anti–PD-1 and anti–CTLA-4 antibodies tended to be associated with a higher grade of rash. Grade 3 rash was observed in patients receiving anti–PD-1 therapy (n = 2) and combined anti–PD-1 and anti–CTLA-4 therapy (n = 1).
In our study, 20 of 42 (47.6%) rashes were treated with systemic steroids, namely prednisolone at doses of <0.4 (7/20, 35.0%), 0.4–1.0 (7/20, 35.0%), and >1.0 mg/kg (6/20, 30%). In two cases, steroid pulse therapy (intravenous methylprednisolone 1000 mg/day for 3 consecutive days) was used. Both patients were receiving combination therapy with anti–PD-1 and anti–CTLA-4 antibodies, and both rashes were maculopapular rashes. In the case of psoriasiform reaction (n = 1), topical active vitamin D was added to topical steroid and systemic antihistamine.
Interruption of ICI therapy occurred in multiple rash types because of the eruption severity. In total, 7 of 42 cases (16.7%) resulted in temporary interruption, and 19 of 42 cases (45.2%) resulted in permanent discontinuation. Most patients who developed extracutaneous irAEs required temporary treatment interruption (2/10) or permanent discontinuation (7/10) regardless of the rash grade of rash.
In total, 40 of 42 (95.2%) rashes (including those that were exacerbated on subsequent ICI administration) improved with appropriate dermatologic therapy, interruption of immunotherapy, or both. Only 2 of 42 (4.8%) rashes did not respond to dermatologic treatment and interruption of immunotherapy.