Dr Tarantino on the CompassHER2 pCR Trial of THP in HER2+ Breast Cancer

“The idea behind this trial was to see the performance of neoadjuvant THP without any further cytotoxic treatment in terms of 3-year RFS [rate].”

Paolo Tarantino, MD, PhD, a research fellow in the Department of Medicine at Dana-Farber Cancer Institute and Harvard Medical School, discussed the key design characteristics of the phase 2 CompassHER2 pCR trial (NCT04266249).

CompassHER2 pCR was a large, single-arm trial that enrolled patients with stage II to IIIA HER2-positive breast cancer, Tarantino began. The study evaluated neoadjuvant treatment with a taxane plus trastuzumab (Herceptin) and pertuzumab (Perjeta; THP), he continued. The study enrolled 2175 patients, he added. Those who achieved a pathologic complete response (pCR) following surgery then received de-escalated treatment with trastuzumab and pertuzumab for 1 year; patients with evidence of residual disease after surgery received additional chemotherapy and anti-HER2 treatment, or could choose to enroll in a clinical trial, he explained.

The de-escalation approach was previously assessed in patients with HER2-positive breast cancer in the phase 1 DAPHNe trial (NCT03716180) and the phase 2 ADAPT trial (NCT01817452), Tarantino noted. The goal of CompassHER2 pCR was to determine the 3-year recurrence-free survival (RFS) rate with neoadjuvant THP without further cytotoxic treatment, he said. 3-year RFS data are still developing, however during the 2025 ASCO Annual Meeting, investigators presented pCR rate findings with the approach, he concluded.

The median age at baseline was 55 years. Most patients were White (75%), had an ECOG performance status of 0 (88%), had clinical stage IIA disease (58%), and had clinical stage T2 disease (75%). Patients received paclitaxel (63%), docetaxel (34%), or nab-paclitaxel (Abraxane; 2%) as the taxane component of the regimen. Tumor histologies consisted of ductal (93%), lobular/mixed (5%), or other (3%).

Patients received 4 cycles of THP, which consisted of paclitaxel at 80 mg/m² once a week for 12 weeks or docetaxel at 75 mg/m² every 3 weeks for 4 cycles, in combination with trastuzumab and pertuzumab every 3 weeks for 4 cycles.