Trotabresib in Combination With Vinorelbine and Radiation Therapy for the Treatment of HER2+ Breast Cancer With Central Nervous System or Leptomeningeal Metastasis

This phase I/Ib trial tests the safety, side effects, and best dose of vinorelbine when given in combination with trotabresib in treating patients with HER2 positive breast cancer that has spread to the central nervous system or leptomeninges (metastasis). Cancer cells that make too much HER2 may grow more quickly and are more likely to spread to other parts of the body as metastases, including the central nervous system. Trotabresib is part of a family of drugs called BET inhibitors. Trotabresib may stop the growth of tumor cells by blocking some of the enzymes needed for cell growth. Vinorelbine is in a class of medications called vinca alkaloids. It works by slowing or stopping the growth of cancer cells in your body. Giving trotabresib and vinorelbine may increase in the anti-cancer activity of vinorelbine when used in combination with radiation (radiotherapy).