New Drug Combination for Advanced Breast Cancer Delays Disease Progression

The gist: A new treatment that combines the drugs bortezomib and fulvestrant has shown promise in treating post-menopausal women with metastatic hormone receptor-positive breast cancer whose disease worsened after being treated with drugs called aromatase inhibitors. The combo treatment was tested in 118 patients in a clinical trial. It doubled the number of patients still alive after 12 months, and it lowered the chance of patients’ cancer worsening. Further studies will continue to measure the effectiveness of the treatment.

“A new combination of cancer drugs delayed disease progression for patients with hormone-receptor-positive metastatic breast cancer, according to a multi-center phase II trial. The findings of the randomized study (S6-03) were presented at the 2014 San Antonio Breast Cancer Symposium, held Dec. 6-9, by Kerin Adelson, M.D., assistant professor of medical oncology at Yale Cancer Center and chief quality officer at Smilow Cancer Hospital at Yale-New Haven.

“The trial enrolled 118 post-menopausal women with metastatic hormone-receptor-positive breast cancer whose cancer continued to progress after being treated with an aromatase inhibitor. The study, based on work done by Doris Germain of Mt. Sinai Hospital, found that the combination of the drugs bortezomib and fulvestrant—versus fulvestrant alone—doubled the rate of survival at 12 months and reduced the chance of cancer progression overall.

“Bortezomib, used most commonly in treating multiple myeloma, is a proteasome inhibitor that prevents cancer cells from clearing toxic material. Fulvestrant causes clumping of the estrogen-receptor protein. When bortezomib blocks the ability of the cell to clear these protein clumps, they grow larger and become toxic to the cancer cells. This, in turn, amplifies the effectiveness of fulvestrant, a drug commonly used in this subset of patients.

“The drug combination doubled the number of patients whose cancer had not progressed after one year from 14% to 28%, according to Adelson.”