A Study of Tucatinib and Trastuzumab in People With Rectal Cancer

Patients will then be given tucatinib (300 mg BID orally) and trastuzumab (8 mg/kg on day 1, then 6 mg/kg starting cycle 2 and every three weeks) therapy for an initial 6 week lead-in period. All patients, regardless of findings on rectal MRI will then transition to standard of care induction chemotherapy with continuation of the trastuzumab and tucatinib for a total of five additional cycles (15 extra weeks).

Patients will then be given tucatinib (300 mg BID orally) and trastuzumab (8 mg/kg on day 1, then 6 mg/kg starting cycle 2 and every three weeks) therapy for an initial 6 week lead-in period. All patients, regardless of findings on rectal MRI will then transition to standard of care induction chemotherapy with continuation of the trastuzumab and tucatinib for a total of five additional cycles (15 extra weeks).