More than twice as many women with early stage, HER-2 positive breast disease who received Herceptin along with pre-surgery chemotherapy, compared to chemotherapy alone, had their tumors completely disappear, according to an M. D. Anderson study.
Findings from the study were presented at the American Society of Clinical Oncology (ASCO) meeting in June by Aman Buzdar, M.D., professor in the Department of Breast Medical Oncology at M. D. Anderson. He reported that more than 65% of early stage, HER-2 positive patients experienced a complete response rate after receiving Herceptin with chemotherapy, compared to 26% of patients with similar tumor types who received chemotherapy only.
Because the results from the 42 study participants were so striking, the Phase III trial was halted early so that all newly diagnosed M. D. Anderson patients with early stage, HER-2 positive tumors can benefit from the superior treatment of Herceptin plus chemotherapy prior to surgery. Had the trial continued to accrue 164 patients as originally planned, there was a 95% probability that patients receiving the Herceptin would experience similar outcomes, he reported.
All trial participants had surgery after completing chemotherapy alone or chemotherapy with Herceptin. According to Buzdar, even though most of the breast tumors either virtually disappeared or shrank dramatically with the treatment, the breast still had to be treated surgically.
Few major side effects were reported in the trial, including heart damage — a symptom often attributed to Herceptin. Patients received epirubicin as one of three drugs in the chemotherapy regimen, which has been shown to be less toxic to the heart. Fevers or neutropenia were experienced by a small percentage of patients, particularly among those on the Herceptin arm of the trial.
About 25% to 30% of all breast cancer patients have tumors that are HER-2 positive, a tumor marker that can signal a poorer prognosis due to increased risk of recurrence and decreased sensitivity to chemotherapy.
Going one step beyond
When Buzdar and his team began the study more than two years ago, they wanted to go one step beyond previous studies that showed Herceptin plus chemotherapy could extend survival and control disease in patients with advanced or metastatic breast cancer.
“When we started this trial with early stage breast cancer patients, we had hoped to see a 20% improvement in complete response, but actually we found a 39% improvement with the addition of Herceptin,” he says. “This is a significant stride in treating women with confined breast tumors which have tested positive for the HER-2 gene. In my 30-plus years of clinical research in breast cancer, I believe these are among the most striking results I have seen.”
Buzdar says the research team will build on the data and experience gained from this trial and develop future studies that will explore results in a larger group of patients. It also will look more closely at the effect the treatment may have on the type of surgery necessary after chemotherapy.