Among women whose breast cancer continued to spread (metastasize) after treatment, adding the cancer drug Afinitor to a hormone drug called Aromasin more than doubled the time before the disease got worse.
In both studies, women given the combination treatments lived a matter of months, not years, longer before their cancer got worse.
"But eventually all women with metastatic disease get worse. These are some of the best data we've seen here. The drugs could be game changers," says Jose Baselga, MD, PhD, chief of oncology and hematology at Massachusetts General Hospital in Boston.
Baselga worked on both studies, presented here at the San Antonio Breast Cancer Symposium and published online by The New England Journal of Medicine.
Afinitor blocks a protein that some cancer cells need to divide, multiply, and spread. It's already used to treat advanced kidney cancer and other tumors.
Aromasin blocks an enzyme the body uses to make estrogen. It's approved by the FDA to reduce the risk of cancer recurrence in certain postmenopausal women.
At the meeting, Baselga reported that cancer got worse in women given Aromasin and Afinitor after an average of about seven-and-a-half months, compared with just over three months for those given Aromasin alone.
The most common serious side effects of Afinitor were mouth ulcers, shortness of breath, and anemia. Still, the side effects are not as severe as those associated with traditional chemo, he tells WebMD.
"This is the first study to ever show a benefit in these women," Edith Perez, MD, of the Mayo Clinic in Jacksonville, Fla., tells WebMD. She was not involved with the work.
The study included 724 postmenopausal women with a certain type of tumor fueled by estrogen.
Each year, about 220,000 women around the world are diagnosed with this type of advanced breast cancer.
The study, known as BOLERO-2, was stopped early because the women taking Afinitor did so much better.
Novartis, which makes the drug and funded the study, is applying for approval for this use. But because both drugs are commercially available, they could be prescribed by doctors already.
Baselga consults for a number of drug companies, including Novartis and Genentech.