Alectinib efficacy in advanced lung adenocarcinoma with coexistence of a novel ALK-MTUS2 and STRN3-ALK double fusion: A case report and literature review.

In total, >90 unique anaplastic lymphoma kinase (ALK) rearrangement fusion partners have been identified, each with a unique sensitivity to ALK tyrosine kinase inhibitors, rendering targeted therapy challenging. In the present study, the efficacy of alectinib in a patient with advanced lung adenocarcinoma harbouring a novel ALK-microtubule-associated tumour suppressor candidate 2 (MTUS2) fusion and a rare Striatin 3 (STRN3)-ALK fusion was assessed. A 20-year-old non-smoker was hospitalised with a persistent cough. Subsequent positron emission tomography/computed tomography revealed a tumour in the right lower lobe, with mediastinal, hilar, lymph node and bone metastases. Cranial magnetic resonance imaging also revealed a cerebral metastasis. Bronchoscopic biopsy revealed an adenocarcinoma in the right lower lobe nodule, resulting in a clinical stage IVB diagnosis (cT2bN3bM1c). Targeted next-generation sequencing of tissue and blood samples revealed ALK-MTUS2 and STRN3-ALK fusions. The patient was treated with alectinib as the first-line therapy and a durable partial response was achieved after 3 months, with disappearance of the brain metastases. To the best of our knowledge, the present study represents the first discovery of simultaneous ALK-MTUS2 and STRN3-ALK fusions. The clinical outcome offers potential therapeutic options for patients with rare ALK rearrangements and underscores the necessity for further research on the functions of these fusions.