A Recurrent Small Cell Lung Carcinoma Harboring an EML4-ALK Fusion Mutation with Sustained Response to Ensartinib: A Case Report.

Small cell lung cancer (SCLC) is an aggressive neuroendocrine tumor. Lung cancer patients with ALK and EML4 fusions respond significantly to ALK inhibitors. The EML4-ALK fusion gene mutation is the result of an inversion of chromosome 2, which juxtaposes the 5 end of the EML4 gene with the 3 end of the ALK gene. In SCLC, the frequency of fusion genes is very low, and to the best of our knowledge, only four cases of ALK fusion gene mutations in SCLC have been reported. In this report, we describe the treatment of a 74-year-old female patient with SCLC who developed recurrence of hilar lymph node metastasis three years after surgical resection. Postoperative NGS showed that this patient is a SCLC patient harboring a rare EML4-ALK fusion mutation, and a satisfactory 43-month overall survival (OS) was achieved after treatment with ensartinib targeting the EML4-ALK fusion gene mutation. The ALK-TKI may be a new treatment option for these patients. This article provides a therapeutic reference.