First Report of Management of Sequential Small Cell Transformation and ALK I1171T Mutation as Resistance Mechanisms in a Patient With ALK-EML4 Fused Non–Small Cell Lung Adenocarcinoma With a Novel Combination of Temozolomide and Lorlatinib: A Case Report

ALK-EML4 fusion-positive lung adenocarcinomas (LUADs) are effectively treated with ALK tyrosine kinase inhibitors, but most patients eventually develop resistance to these drugs owing to ALK-dependent or independent mechanisms. Endothelial to mesenchymal transformation with SCLC development is an ALK-independent mechanism of resistance that has not been previously reported with sequential ALK I1171T mutation while the patient is on treatment for the SCLC. Here, we report the first case of sequential SCLC transformation followed by ALK I1171T mutation in a patient with ALK-EML4 fusion-positive LUAD. After progression on multiple lines of therapy, we describe our experience of managing ALK-mutant LUAD and transformed SCLC with a novel combination of lorlatinib and temozolomide. We also briefly summarize cases of endothelial to mesenchymal transformation ALK-mutant LUAD from the literature.