Abstract: 【Abstract】 Objective To investigate the clinical characteristics, treatment strategies, and outcomes of Stevens-Johnson syndrome （SJS） and toxic epidermal necrolysis （TEN） induced by programmed cell death 1 （PD-1） inhibitors. Methods This study was a retrospective case series. Clinical data were collected from 13 hospitalized patients with PD-1 inhibitor-induced SJS/TEN admitted to the Department of Dermatology, the First Affiliated Hospital of Soochow University between January 2018 and September 2024. The Naranjo Adverse Drug Reaction Probability Scale and the Algorithm of Drug Causality for Epidermal Necrolysis （ALDEN） were employed to assess suspected causative agents. Clinical manifestations, treatment regimens, and outcomes were analyzed. Results Of the 13 patients with SJS/TEN, 10 were males and 3 were females. There were 6 patients with SJS-TEN overlap, 4 with SJS, and 3 with TEN. The age at onset was 65.23 ± 8.91 years （range, 45 - 78 years）. The median disease duration was 14 days （range, 7 - 120 days）. All patients had solid malignant tumors. Based on Naranjo and ALDEN scores, the most probable causative drugs were sintilimab, tislelizumab, serplulimab, toripalimab, pembrolizumab, and camrelizumab. The median latency period from PD-1 inhibitor initiation to the onset of SJS/TEN was 36 days （range, 14 - 300 days）. The epidermolysis area was 26.08% ± 22.11%. Mucosal involvement occurred in 10 patients, prodromal rashes in 4, and bacteremia in 3. All the patients were treated with systemic glucocorticoids alone or in combination with intravenous immunoglobulin （IVIg） and/or etanercept, alongside supportive care and intensive skin care. The treatment duration was 21.23 ± 10.19 days. Following treatment, 10 patients showed clinical improvement and 3 died. Conclusions PD-1 inhibitor-induced SJS/TEN was characterized by a prolonged latency, severe clinical manifestations, and high mortality. Discontinuation of the offending agents and early initiation of high-dose systemic glucocorticoids, either alone or in combination with IVIg and/or etanercept, may improve clinical outcomes.

Key words: Drug eruptions, Stevens-Johnson syndrome, Toxic epidermal necrolysis, Programmed cell death 1 inhibitor, Clinical characteristics