A Study of Oral LOXO-292 (Selpercatinib) in Pediatric Participants With Advanced Solid or Primary Central Nervous System (CNS) Tumors

This study includes 2 parts: phase 1 (dose escalation) and phase 2 (dose expansion). In phase 1, participants will be enrolled using a rolling 6 dose escalation scheme. The starting dose of LOXO-292 is equivalent to the adult recommended phase 2 dose of 160 milligrams (mg) twice a day (BID). Once the maximum tolerated dose (MTD) and/or recommended phase 2 dose (RP2D) is identified, participants will be enrolled to one of four phase 2 dose expansion cohorts depending on tumor histology and tumor genotype. Cycle length will be 28 days.