Adding Dasatinib Doubles Progression-Free Survival in Certain Breast Cancers

The addition of dasatinib to aromatase inhibitors demonstrated a doubling in the duration of progression-free survival among women with hormone receptor-positive, HER2-negative metastatic breast cancer. These results were recently presented at the 2013 annual San Antonio Breast Cancer Symposium (SABCS).

The majority of breast cancers are hormone receptor-positive, or HR+, meaning that the cancer cells are stimulated to grow from exposure to the female hormones, estrogen and/or progesterone.

Treatment for HR+ breast cancers consist of hormone therapy, which is a type of therapy that reduces the amount of circulating female hormones in the body, ultimately “starving” the cancer cells of their growth stimulus. Aromatase inhibitors (AIs) are one type of hormone therapy commonly used in the treatment of HR+ breast cancers. Although AIs are effective in the treatment of HR+ breast cancers, researchers continue to explore ways to improve the duration for which they produce anti-cancer responses.

Dasatinib is an agent that is approved for the treatment of certain types of leukemia. It blocks processes within cells that have been implicated in pathways involved in the spread of some cancers.

Researchers from the United States recently conducted a clinical trial to evaluate the addition of dasatinib to an AI in the treatment of women with advanced breast cancer. The trial included 120 postmenopausal women with locally recurrent or metastatic HR+, Her2-negative breast cancer. Patients were treated with either the AI letrozole, in combination with dasatinib, or letrozole alone.

The median time of survival with no progression of cancer was 20.1 months for those treated with dasatinib plus letrozole, compared to 9.9 months for those treated with letrozole alone.
Treatment with dasatinib plus letrozole was generally very well tolerated.
The researchers stated that their hope is the addition of dasatinib can prolong the time that letrozole provides anti-cancer activity among postmenopausal, HR+ women with advanced breast cancer. Potentially, this treatment strategy can be used among HR+ breast cancers in the earliest stages as well.

Reference: Paul D, Vukelja SJ, Holmes FA, et al. Letrozole plus dasatinib improves progression-free survival (PFS) in hormone receptor-positive, HER2-negative postmenopausal metastatic breast cancer (MBC) patients receiving first-line aromatase inhibitor therapy. Proceedings from the 2013 San Antonio Breast Cancer Symposium. Abstract S3-07.