Ensartinib Treatment for Rare Nonclassical ALK Fusion Lung Adenocarcinoma With Brain Metastasis

ALK rearrangements are uncommon but actionable oncogenic drivers in non-small cell lung cancer. STRN - ALK fusions are rare among the nonclassical ALK fusion types, and they pose problems diagnostically and therapeutically. A 50-year-old woman had a 2-year history of cough, sputum, and wheeze. Initial workup revealed a severe mixed ventilatory defect, and imaging demonstrated left lung obstruction with mediastinal lymphadenopathy. Bronchoscopy confirmed mucinous adenocarcinoma, and molecular testing revealed a rare STRN - ALK fusion. Because of the patient's clinical deterioration and concurrent brain metastases diagnosis, ensartinib was started in conjunction with chemotherapy. The patient had a significant improvement in symptoms, including weight gain. Imaging showed a reduction in total tumor burden and no new lesions on follow-up. The results suggested that ensartinib provided central nervous system stability and long-term tumor control. This is unlike prior descriptive accounts of patients with STRN - ALK fusion lung adenocarcinoma.