Treatment with the bisphosphonate zoledronate did not improve outcomes for women with chemoresistant breast cancer, according to initial results of a phase III clinical trial presented here at the 2013 San Antonio Breast Cancer Symposium, held Dec. 10-14.
Many patients with breast cancer are treated with chemotherapy prior to surgery. In some patients who receive this form of treatment, which is called neoadjuvant therapy, no residual invasive cancer can be detected in breast tissue samples and lymph nodes removed during surgery. Patients with residual disease are considered to have breast cancer that is resistant to chemotherapy, and emerging data indicate that they experience poorer long-term outcomes compared with women who respond completely to neoadjuvant therapy.
"Because patients with residual disease after neoadjuvant chemotherapy are considered to have chemoresistant breast cancer, they have few postsurgery treatment options," said Gunter von Minckwitz, M.D., Ph.D., chairman of the German Breast Group in Neu-Isenburg, Germany. "We evaluated a new postsurgery treatment for these patients, the bisphosphonate zoledronate, in a phase III clinical trial.
"We are disappointed to report that zoledronate had no effect on event-free survival. That is, it had no effect on the number of patients who had disease relapse, developed a new cancer, or died.Although the results are completely negative, we hope that our experience running the first phase III clinical trial to test a treatment in women who had not had a complete response to neoadjuvant therapy will inform future post-neoadjuvant phase III clinical trials," added von Minckwitz, who is also professor of gynecology at the University of Frankfurt. "We experienced a number of challenges while conducting this study, and are sharing what we have learned with other researchers running, or thinking of running, these extremely complicated clinical trials."