Overcoming Central β-Sheet #6 (Cβ6) Mutation (L1256F), Mutations and Short Forms of and Splice Variants are the Unmet Need That a Re-Imagined 5th-Generation (5G) ALK TKI Must Deliver.

Despite the development and approval of seven anaplastic lymphoma kinase (ALK) tyrosine kinase inhibitors (TKIs) spanning over three "generations" since the discovery of fusion positive () non-small cell lung cancer (NSCLC), there remains intrinsic and acquired resistances to these approved TKIs. Currently, a fourth-generation (4G) ALK TKI, NVL-655, is being developed to attack some of the unmet needs such as compound resistance mutations . However, and mutations are intrinsic genomic alterations that negatively modulate efficacy of ALK TKIs. Potentially, in the shifting landscape where lorlatinib should be the first-line ALK TKI of choice based on the CROWN trial, the central β-sheet #6 (Cβ6) mutation will be the potential acquired resistance mutation to lorlatinib which may be resistant to current ALK TKIs. Here we opine on what additional capacities a putative fifth-generation (5G) ALK TKI will need to possess if it can be achieved in one single molecule. We propose randomized trial schemas targeting some of the intrinsic resistance mechanisms that will lead to approval of a prototypic fifth-generation (5G) ALK TKI and actually be beneficial to NSCLC patients rather than just design a positive pivotal superiority trial for the sole purpose of drug approval.