Summary: This is a Phase Ib/II, open-label, multicenter, randomized umbrella study in participants with breast cancer. The study is designed with the flexibility to open new treatment arms as new treatments become available, close existing treatment arms that demonstrate minimal clinical activity or unacceptable toxicity, or modify the patient population. Cohort 1 will focus on participants with inoperable...

Summary: This study is being done to find out if tucatinib with other cancer drugs works better than standard of care to treat participants with HER2 positive colorectal cancer. This study will also determine what side effects happen when participants take this combination of drugs. A side effect is anything a drug does to the body besides treating your disease. Participants in this study have colorectal c...

Summary: The purpose of this study is to evaluate the safety and efficacy of the three-drug combination of tucatinib, trastuzumab, and eribulin in patients with de novo and recurrent unresectable metastatic HER-2/neu positive breast cancer as assessed by ORR, PFS and OS after prior treatment with a taxane, trastuzumab, and T-DM1.