Alectinib-Induced Erythema Multiforme and Successful Rechallenge with Alectinib in a Patient with Anaplastic Lymphoma Kinase-Rearranged Lung Cancer

BACKGROUND: Alectinib is an oral drug developed for the treatment of patients with fusion gene encoding echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK)-rearranged non-small cell lung cancer (NSCLC). Here, we present the case of a patient treated with alectinib who developed a hypersensitivity reaction with successful rechallenge treatment. CASE PRESENTATION: A 39-year-old woman who was a passive smoker was referred to Osaka City University Hospital for the evaluation of a skin event caused by treatment for NSCLC with the fusion gene EML4-ALK. The skin reaction was observed on the anterior chest, upper arms, and ear auricles on day 11 of treatment with oral alectinib. The skin event presented as widely distributed erythematous macules that were confluent, indicating a severe and life-threatening form. The skin lesions started to resolve after the initiation of treatment with 40 mg prednisolone. After regrowth of the tumor, she received a rechallenge program for alectinib for 2 weeks; thereafter, alectinib treatment was successfully reinitiated. CONCLUSION: To the best of our knowledge, we present the first case in which alectinib, which binds to the adenosine triphosphate site of EML4-ALK, induced erythema multiforme. Moreover, successful readministration of alectinib through our rechallenge program has not been reported so far.