Response of a Novel KANK1::ALK Fusion to Alectinib in an Advanced Lung Adenocarcinoma: A Case Report

More than 90 distinct fusion partners of ALK rearrangement have been identified. Different ALK fusions may exhibit different sensitivities to ALK tyrosine kinase inhibitors. The emergence of rare fusions poses significant challenges to targeted therapies. This study aimed to investigate the response of KANK1::ALK fusion to alectinib in an advanced lung adenocarcinoma. A novel KANK1::ALK fusion was identified by next-generation sequencing (NGS) and Ventana immunohistochemistry assessments. A 73-year-old woman who had never smoked was admitted with hemoptysis in May 2020. PET/CT revealed a nodule in the left upper lobe, with bilateral pulmonary and multiple lymph node metastases. The upper lobe nodule of the left lung was diagnosed as adenocarcinoma through bronchofiberscopy biopsy, resulting in a clinical diagnosis of stage IVA (cT1c,N3,M1a). Because the biopsy tissue was insufficient for NGS analysis, a blood-based genetic analysis was performed, revealing the presence of KRAS p.Q61R mutations. The patient received carboplatin and pemetrexed with pembrolizumab as first-line therapy, followed by maintenance therapy of pembrolizumab monotherapy. Although the tumor initially showed significant shrinkage, it unfortunately progressed further after 11 months. Subsequently, the patient was given carboplatin and pemetrexed with pembrolizumab again, but the tumor progression continued. An NGS using a rebiopsy of the left upper lobe tumor suggested a KANK1::ALK fusion. Alectinib was prescribed in January 2022, and a durable partial response was observed after 18 months. ALK rearrangements were observed in the broader spectrum of lung cancers. This study provided a potential treatment option for patients with KANK1::ALK fusions. Further studies are needed to understand the function of these fusions.