Alliance A011801 / CompassHER2 RD — The CompassHER2 Trials (COMprehensive Use of Pathologic Response ASSessment to Optimize Therapy in HER2-Positive Breast Cancer): CompassHER2 Residual Disease (RD), A Double-Blinded, Phase III Randomized Trial of T-DM1 and Placebo Compared With T-DM1 and Tucatinib

Phase 3 · Breast Cancer

Population

Patients with high-risk HER2-positive early breast cancer with residual invasive disease after neoadjuvant HER2-directed therapy and surgery.

Primary Endpoint

Invasive disease-free survival (iDFS)

Rationale

Despite adjuvant T-DM1 (KATHERINE), patients with residual disease after neoadjuvant therapy retain meaningful relapse risk, especially CNS relapse. Tucatinib crosses the blood-brain barrier and may further reduce recurrence.

What It Could Change

A positive result would establish adjuvant T-DM1 plus tucatinib as a new standard for high-risk HER2-positive breast cancer with residual disease.