Case Report: A Case Report of a Histological Transformation of ALK-Rearranged Adenocarcinoma With High Expression of PD-L1 to Squamous Cell Carcinoma After Treatment With Alectinib

We report an anaplastic lymphoma kinase (ALK)-positive patient shows a poor response to the ALK inhibitor alectinib due to the high expression of programmed death-ligand 1 (PD-L1). After treatment with alectinib, the pathological form changed from adenocarcinoma into squamous cell carcinoma without novel genetic changes. This case may reveal a direct relationship between ALK mutation and a high level of PD-L1 expression.