Implementation of functional precision medicine for anaplastic lymphoma kinase-rearranged non-small lung cancer

Anaplastic lymphoma kinase (ALK)-rearranged kinase drives non-small cell lung cancer (NSCLC) in 3–7% of patients and treatment consists of a broad range of approved inhibitors which are administered sequentially in case of resistance developing invariably after approximately 1 year of therapy. Besides the former standard tyrosine kinase inhibitor (TKI) crizotinib, the second-line ALK inhibitors alectinib, ceritinib, brigatinib, as well as the third-line lorlatinib are approved for the treatment of ALK-positive NSCLC patients. The main challenge is to find individual schemes of ALK inhibitors therapy which provide the best benefit for the patients. A host of ALK fusion partners, rearrangement variants and ALK mutations prevent a direct correlation of ALK alterations and sensitivity to specific TKIs within the framework of genomic precision medicine. However, recurrent ALK-positive NSCLC is an aggressive disease resulting in accumulation of tumor cells in pleural effusions which may be collected for in vitro sensitivity testing in a manner designated as functional precision medicine. Provided that these cells are present in sufficient numbers, they can be exposed to all possible drug candidates and their chemosensitivity tested in short-term proliferation assays. In addition to ALK-directed TKIs, cytotoxic drugs and inhibitors of non-target bypassing pathways may be included in the tests. In contrast to other trials in genome-guided precision medicine, a range of suitable therapeutics is available for modified ALK proteins. In summary, ALK-positive NSCLC with pleural effusions offer a unique model to develop, test and validate concepts of functional precision medicine.