Transformation of NSCLC to SCLC harboring EML4–ALK fusion with V1180L mutation after alectinib resistance and response to lorlatinib: A case report and literature review

Histological transformation from non-small cell lung cancer (NSCLC) to small cell lung cancer (SCLC) with anaplastic lymphoma kinase (ALK) positivity is extremely uncommon in ALK-positive NSCLC. To date, there have been limited reports regarding cases of SCLC transformation, and the optimal therapeutic strategies and prognosis for such patients remain unclear. This case is the first to describe the effectiveness of lorlatinib in treating a patient with SCLC that transformed from NSCLC harboring the ALK fusion V1180L mutation following acquired resistance to alectinib therapy.