Breast Cancer Research Foundation investigator Nadine M. Tung led the CompassHER2-pCR trial, which found that some patients achieved a pathological complete response with less chemotherapy.
Key Takeaways
- A study from the ECOG-ACRIN Cancer Research Group’s CompassHER2-pCR trial found that some early-stage HER2-positive breast cancers may be treatable with less chemotherapy than is standard.
- Patients were given a combination treatment of a single chemotherapy drug and two HER2-targeted drugs.
- Researchers found that 48.3% of participants achieved a pathological complete response after surgery.
- Researchers will continue to follow patients for three years to assess overall survival.
Some early-stage HER2-positive breast cancers may require less intensive chemotherapy. This is the major takeaway from the CompassHER2-pCR trial, from the ECOG-ACRIN Cancer Research Group.
Breast Cancer Research Foundation (BCRF) investigators played an important role in these findings. In fact, Dr. Nadine M. Tung led the trial, which found some patients may be able to undergo less chemotherapy. Though a powerful treatment, chemotherapy comes with various side effects that can linger and impact quality of life.
The clinical trial involved 2,175 patients, making it the largest prospective trial of its kind. The study examined clinical and molecular predictors of pathologic complete response (pCR).
Prior to surgery, patients received treatment comprised of a single chemotherapy drug (taxane) and two HER2-targeted drugs (trastuzumab and pertuzumab), as opposed to the multi-agent chemotherapy that is typically given to patients with early-stage (stages 2-3A) HER2-positive breast cancer. After surgery, 43.8% of the 2,141 participants who underwent single chemotherapy in combination with dual HER2-targeted treatment had a pathologic complete response, meaning no invasive cancer remained.
The results suggest that certain tumor characteristics were associated with a greater likelihood of having a pathologic complete response after this treatment regimen: These included estrogen receptor (ER) -negative or low ER-expressing tumors; low or no progesterone (a steroid associated with the female reproductive system) receptor levels, high levels of HER2 protein (which directs cell growth and repair), and receiving the chemotherapy medication paclitaxel weekly.
Researchers also evaluated HER2DX, a molecular biomarker test designed to provide prognostic and predictive information about early-stage HER2-positive breast tumors. Investigators found that the pCR rate was 68% in the group with high HER2DX scores, compared with 19% in those with low scores. Their findings suggest that HER2DX results combined with tumor characteristics may help improve the ability to identify patients most likely to achieve pCR with a less intensive chemotherapy approach.
For patients with a pathologic complete response, follow-up will continue for three years to assess if they remain cancer-free. The trial results were published in the Journal of Clinical Oncology. More research is needed before this becomes practice-changing, as results are still pending and more research is needed to determine how this should be used to guide treatment.
