Researchers from the Czech Republic have reported that Faslodex® (fulvestrant) appears to have a clinical benefit in 61% of women who are receiving the hormonal therapy drug through an expanded access program. These results were presented at the 29th European Society of Medical Oncology (ESMO) Congress held in Vienna, Austria, October 29 to November 3, 2004.
Breast cancer is the second leading cause of cancer death in women in the United States, with approximately 200,000 cases diagnosed each year. An important approach to the treatment of breast cancer is hormonal therapy, which reduces the level of estrogen in the body. Estrogen is an essential female hormone that is produced by the ovaries and adrenal glands; however, it can also cause some cancers to grow. The breasts, uterus and other female organs are composed of cells that are stimulated to grow when exposed to estrogen. These cells have estrogen receptors on their surface. Estrogen circulating in the blood binds to these receptors and stimulates growth-related activities in the cell. When cells that have estrogen receptors become cancerous, exposure to estrogen increases the cancer’s growth. Cancer cells that have estrogen receptors are referred to as estrogen receptor-positive (ER-positive) cancers.
There are several different types of hormonal therapy designed to reduce estrogen levels, including the common selective estrogen receptor modulator (SERM) tamoxifen, as well as several newer drugs referred to as aromatase inhibitors. Faslodex® is a hormonal therapy that works through a mechanism that is different from tamoxifen or the aromatase inhibitors. Rather than inhibit the estrogen receptors on the cell surface, as with tamoxifen, or interrupt the conversion of estrogens to their active form, as with the aromatase inhibitors, Faslodex® degrades the estrogen receptor. It is believed that this different impact on the estrogen receptor produces beneficial results for women who have stopped responding to tamoxifen.
In an expanded access program at the Charles University in Prague, 64 women with metastatic breast cancer were treated with Faslodex® injection (5 mL) once every 28 days until disease progression. All patients had received prior hormonal therapy. Most of the patients (87%) had ER-positive disease, and nearly half (44%) had Her2-positive disease.
After a median of 7 months, 5 patients (8%) responded to treatment and 34 (53%) had stable disease that lasted for at least 6 months. Taken together, these results demonstrate a clinical benefit (response to treatment or stable disease) in 61% of patients.
Reference: Petruzelka L, Zimovjanova M, Konopasek B, et al. Fulvestrant in Postmenopausal Women with Metastatic Breast Cancer Progressing on Prior Endocrine Therapy-Updated Results From an Expanded Access Programme. Proceedings from the 29th ESMO Congress, Vienna Austria, October 29-November 2, 2004; (Abstract #136).