Adjuvant crizotinib treatment selected by patient-derived organoids in a patient with stage IIIA adenocarcinoma with novel LRRTM4-ALK fusion: a case report

Background: Over 90 different anaplastic lymphoma kinase (ALK) fusions have been reported, and patients with different ALK fusion partners exhibit different responses to targeted therapy. Patient-derived organoid (PDO), a kind of 3-dimensional culture, is a promising model for drug-sensitivity testing for personalized treatment decision-making. It further has the potential to provide treatment strategy for patients with novel mutations, rare mutations, and concomitant mutations, serving as a supplement to evidence-based medicine. Case Description: We report a case in which a man with stage IIIA adenocarcinoma had pleural effusion 1 month after surgery. A novel leucine-rich repeat transmembrane neuronal protein 4 (LRRTM4)-ALK fusion was unveiled by next-generation sequencing (NGS), and PDOs were used in drug-sensitivity testing to select a proper adjuvant therapy for this patient. We chose crizotinib based on result of the test and drugs' availability in China and helped the patient achieve a more than 3-year-long disease-free survival (DFS). Higher variant allele frequencies (VAFs) of the driver mutation were also found in PDOs and their waste culture medium, indicating that the PDO model could filter out cells with driver genes or stemness and help us to identify the critical cancer cell colony in treatment decision-making. Conclusions: For the first time, we report the case of a LRRTM4-ALK fusion. The patient achieved a more than 3-year long-term DFS under crizotinib treatment, which was selected by an emerging PDO drug-sensitivity test model. We also discovered the enrichment of a low-abundance driver mutation in PDO and its waste culture medium, providing a new direction for future research.