Drug reactions with eosinophilia and systemic symptoms induced by immune checkpoint inhibitors: an international cohort of 13 cases.

Among dermatologic adverse events induced by immune checkpoint inhibitors (ICI), drug reactions with eosinophilia and systemic symptoms (DRESS) have been very rarely reported. The objective of this study is to better define the clinical and histologic features, treatment and prognosis of ICI-related DRESS. This retrospective case series was conducted between 01 January 2015 and 31 December 2021 by the dermatology departments of five international networks involved in drug reactions. Inclusion criteria were age ≥18 years old, DRESS with Regiscar score ≥4 (probable or certain) and ICI as a suspect drug. Clinical, biologic and follow-up data were extracted from the medical charts. Thirteen patients were included. The median time to onset was 22 days (3-11). No patients had a high-risk drug introduced in the past 3 months. A majority of patients presented fever (92%), diffuse exanthema (77%) and facial edema (69%). Biologic features included hypereosinophilia in eight patients (61.5%), hyperlymphocytosis in 3 (23%), elevated liver function tests in 11 (85%, grade 1 or 2 in most cases) and renal involvement in 5 (38%). Two patients (15%) had lung involvement. PCR evidence of viral replication was detected in five patients (38.5%). Treatment involved discontinuation of the suspect ICI and systemic steroids with variable dose and duration regimens. Among the four patients in which ipilimumab + nivolumab combination therapy was initially suspected, one was rechallenged with nivolumab monotherapy with good tolerance. Five patients were switched to another anti-PD-1 plus low-dose systemic steroids, with good tolerance in four cases. No patient died because of DRESS. DRESS induced by ICI are rare and of moderate severity. A consensus for management is still pending.