TRK fusion positive cancers: From first clinical data of a TRK inhibitor to future directions.

Genetic alterations of neurotrophic tropomyosin or tyrosine receptor kinase (NTRK) 1/2/3 genes generate TRK fusion proteins have been reported in a variety of adult and child cancers from diverse cell/tissue lineages. Larotrectinib, a tumour-agnostic TRK inhibitor, has shown remarkable efficacy in a novel "basket" study which has enrolled patients from infants to elderly with different TRK fusion-positive cancers. In this review, we focus on the challenges and expectations on the development of "tumour-agnostic" targeted therapies in rare malignancies.