This study is about testing a medicine called **Dabogratinib**, also known as **TYRA-300**, for people with a type of cancer called **Low Grade Upper Tract Urothelial Carcinoma (LG UTUC)**. Urothelial carcinoma is a cancer that starts in the lining of the urinary system. Participants must be 18 years or older and meet specific health criteria. They should not have high-grade cancer or other types of urothelial cancer. The study will check how well the medicine works and if it is safe. Key Points: - **Study Length**: Participants will be involved in this study for a specific period, as outlined by the study team. - **Visits Needed**: Participants will need to visit study centers as required for treatment and check-ups. - **Treatment Risks**: As with any clinical trial, there may be risks or side effects from the treatment. Participants will be informed about these before joining. Participants should not have had certain cancer treatments recently and must be willing to follow all study procedures. This study aims to provide new insights and potential treatment options for those with LG UTUC.