Adenocarcinoma Harboring Fusion Treated With Osimertinib: A Case Report.

mutations are among the most common driver mutations in lung adenocarcinoma. Rare alterations, such as the fusion, respond to treatment with EGFR tyrosine kinase inhibitors but can be missed by limited genomic sequencing panels. Here, we report a case of metastatic lung adenocarcinoma in a never-smoker patient who initially did not have a targetable alteration identified on two different sequencing panels. The initial response to combination chemoimmunotherapy was short-lived. A rare fusion was then identified using a more in-depth sequencing panel. The patient experienced a dramatic and durable response to osimertinib. This case highlights the rarity of fusions, the efficacy of EGFR tyrosine kinase inhibitors, and the importance of a thorough search for targetable alterations in never-smokers with lung adenocarcinoma.