Researchers from the Memorial Sloan-Kettering Cancer Center in New York recently reported that the treatment combination of Avastin (bevacizumab) and Femara (letrozole) may benefit women with hormone receptor-positive metastatic breast cancer. These results were presented at the San Antonio Breast Cancer Symposium.
A large proportion of breast cancer patients have hormone receptor-positive breast cancer-cancer whose growth is stimulated by the circulating female hormones estrogen and/or progesterone. Hormone therapy is often used to treat hormone receptor-positive breast cancer; it reduces estrogen levels or prevents estrogen from stimulating the growth of cancer cells. Femara, an aromatase inhibitor, blocks the formation of estrogen in the body.
Avastin belongs to a of drugs called monoclonal antibodies. Avastin produces its anticancer effects by targeting vascular endothelial growth factor (VEGF) and preventing the interaction of VEGF to its receptors. VEGF is a protein involved in cellular growth, replication and spread, and new blood vessel formation. Avastin binds to VEGF and inhibits its normal effects. It reduces the growth and spread of cancer cells by inhibiting the growth of new blood vessels, making it harder for the tumor to grow.
Avastin has been evaluated in combination with chemotherapy for the treatment of breast cancer; however, some patients with hormone receptor-positive breast cancer opt for treatment with hormone therapy alone. Prompted by animal studies suggesting a link between estrogen and VEGF, as well as by the manageable side-effects of Avastin, researchers conducted a phase II clinical trial to evaluate the combination of Avastin and Femara for the treatment of hormone receptor-positive metastatic breast cancer.
At the time that results from the study were presented, information was available for 18 patients. All patients were postmenopausal, more than half had cancer that had spread to the lung or liver, and nearly 40% had cancer that had spread to bone. Half the patients had previously been treated with tamoxifen. All patients received Femara (2.5 mg/day) and Avastin (15 mg/kg every 3 weeks).
- 57% of patients had cancer that stabilized (did not worsen) for at least six months.
- A partial reduction in detectable cancer occurred in 9% of patients.
- 13% of patients experienced a worsening of their cancer.
- Hyperglycemia (high blood sugar) occurred in 25% of patients and was the most common adverse event.
- Hypertension, fatigue, and joint pain occurred in 14% of patients.
- Longer follow-up is needed to assess survival.
The researchers concluded that the combination of Avastin and Femara appears to benefit a majority of patients with hormone receptor-positive metastatic breast cancer. Toxic effects of treatment were easily managed.
Reference: Traina T, Dickler M, Caravelli J, et al. A phase II trial of letrozole in combination with bevacizumab, an anti-VEGF antibody, in patients with hormone receptor-positive metastatic breast cancer. Proceedings from the 2005 San Antontio Breast Cancer Symposium. December 2005. Abstract #2030.