The goal of this observational study is to describe the safety and effectiveness of larotrectinib in patients with locally advanced or metastatic TRK fusion cancer for whom a decision to treat with larotrectinib has been made before enrollment. This study will enroll participants with any tumors harboring the NTRK gene fusion including Soft Tissue Sarcomas, Central Nervous System, Melanoma, and Thyroid cancers.

This study has two parts. Part A enrolls patients who have been diagnosed with a solid tumor, lymphoma or desmoid tumor that has either come back ("relapsed") or does not respond to therapy ("is refractory"). Part B enrolls patients with a relapsed or refractory Ewing sarcoma, desmoid tumor, osteosarcoma, liver tumor, Wilms tumor, or tumors with changes in a gene family known as the Wnt pathway. This study involves taking a study drug called tegavivint. The study will be testing different doses of the study drug to find the safest dose.