Probable Stevens–Johnson Syndrome During Taletrectinib Treatment After Crizotinib‐Related Rash in ROS1 ‐Positive Lung Cancer

Severe cutaneous adverse reactions to taletrectinib, a next-generation ROS1 inhibitor for ROS1-rearranged non-small cell lung cancer, remain poorly described. A 52-year-old woman with ROS1-rearranged lung adenocarcinoma developed a Grade 3 rash during crizotinib therapy. After improvement, taletrectinib was initiated. On Day 21, conjunctival hyperaemia appeared, followed by high fever, neutropenia, widespread trunk-dominant erythema, and lower-lip mucosal involvement. Although epidermal detachment, a positive Nikolsky sign, and characteristic epidermal necrosis were absent, and typical target lesions were not documented during the acute phase, the clinical course was considered consistent with probable Stevens-Johnson syndrome. Fever and ocular symptoms rapidly improved after taletrectinib discontinuation and systemic corticosteroid therapy. Infection and human herpesvirus 6 (HHV-6) reactivation were not identified, and ALDEN and Naranjo assessments supported a probable association with taletrectinib. During ROS1-TKI therapy, fever and neutropenia should prompt consideration of severe cutaneous adverse reactions as well as infection.