The primary objective is to determine the recommended dose for further study of oral selitrectinib with previously treated neurotrophic tyrosine kinase (NTRK) cancers in 2 patient groups: a) aged 12 years and older and b) younger than 12 years. Secondary objectives of Phase I are to characterize the pharmakokinetic properties of the test drug, its safety and tolerability, and to assess the objective response rate (ORR) of NTRK-tumors.
