A Study to Test the Effect of the Drug Larotrectinib in Adults and Children With NTRK-fusion Positive Solid Tumors

This research study is done to test how well different types of cancer respond to the drug called larotrectinib. The cancer must have a change in a particular gene (NTRK1, NTRK2 or NTRK3). Larotrectinib is a drug that blocks the actions of these NTRK genes in cancer cells and can therefore be used to treat cancer.