Risk of Stevens–Johnson Syndrome and Toxic Epidermal Necrolysis Among Patients Treated With Immune Checkpoint Inhibitors Compared to Other Antineoplastic Medications: A Nationwide Study

Purpose: This study aimed to assess the risk of Stevens–Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) among patients treated with immune checkpoint inhibitors (ICIs), compared to those receiving molecularly targeted therapies or conventional chemotherapy, using real-world data. Methods: We conducted a nationwide study involving all patients treated with antineoplastic agents in Denmark from May 2018 to December 2024, identified through the Danish National Hospital Medication Registry. SJS/TEN cases were identified within 3 months of each administration using the International Classification of Diseases, 10th Revision codes L51.1 and L51.2, as recorded in the Danish National Patient Register. Incidence rates of SJS/TEN were calculated per 10 000 patients treated, and incidence rate ratios (IRRs) were estimated to compare treatment modalities. Results: Among 91 424 patients treated with antineoplastic agents, 19 developed SJS/TEN. The incidence rates per 10 000 patients treated were 6.89 for ICIs, 1.79 for molecularly targeted therapies, and 1.51 for conventional chemotherapy. Patients receiving ICIs had a higher risk of developing SJS/TEN compared with those receiving molecularly targeted therapies (IRR 3.84, 95% CI 1.39–10.60, p = 0.009) or conventional chemotherapy (IRR 4.57, 95% CI 1.52–11.57, p = 0.001). Conclusion: While the risk of SJS/TEN is higher among patients treated with ICIs compared to those receiving other types of antineoplastic agents, the overall incidence in the real-world setting remains low.