Tucatinib Continuation Study

The study is seeking participants who

• continue to benefit without disease progression from tucatinib as judged by the treating physician.
• are willing to follow protocol requirements. All participants in this study will receive tucatinib. Tucatinib will be taken by mouth 2 times a day. We will examine the experiences of people receiving the study medicine. This will help us assess if tucatinib is safe.

Participants will stay in the study for up to 5 years or until tucatinib is permanently discontinued, whichever comes first. During this time, they will have one clinical visit every three weeks to receive the study treatment. They will also talk with the treating physician about their experiences.

Inclusion criteria

• Be receiving tucatinib as a study intervention and deriving clinical benefit without evidence of disease progression (as determined by the investigator) in a tucatinib Parent Study.
• Agree to follow the reproductive criteria.
• Be willing and able to comply with all scheduled visits, treatment plan, and other study procedures as outlined in this protocol.
• Be capable of giving signed informed consent.

Exclusion criteria

• Any medical reason that, in the opinion of the investigator or sponsor, precludes the participant from inclusion in the study.
• Current use of any prohibited concomitant medications(s) or unwillingness or inability to use a required concomitant medication(s).
• Participants not previously enrolled or who have discontinued study intervention or who were randomized in the control arm in a Parent Study.