Researchers from Europe recently reported results from a phase II clinical trial indicating that the addition temsirolimus to Femara® (letrozole) resulted in longer survival without cancer progression in postmenopausal women with advanced breast cancer. These results were recently presented at the 28th San Antonio Breast Cancer Symposium (SABCS).
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.
Temsirolimus is an agent that controls the growth of cells by blocking cell signals and preventing cell division. It is being evaluated in the treatment of several cancers, including kidney cancer, breast cancer, mantle cell lymphoma, and glioblastoma multiforme.
To evaluate the effect of adding Temsirolimus to treatment with Femara, researchers in Europe conducted a phase II clinical trial. The trial enrolled 92 postmenopausal women with advanced, hormone-receptor positive breast cancer. Women were randomly assigned to receive one of the following three treatment regimens: temsirolimus (10 mg per day) plus Femara; temsirolimus (30 mg per day) plus Femara; or Femara alone. The following preliminary findings were presented:
- Patients treated with temsirolimus and Femara had longer survival without cancer progression.
- Patients treated with 30 mg of temsirolimus had better outcomes than patients treated with 10 mg of temsirolimus.
- 21% of patients treated with Femara alone experienced a stabilization of cancer that lasted at least six months, compared to 37% of patients treated with Femara and 30 mg of temsirolimus.
- The median duration of survival without cancer progression was 9.5 months for patients treated with Femara alone and 18 months for patients treated with Femara and 30 mg of temsirolimus.
- As of October 2005, 31% of patients treated with Femara alone had died, compared to 17% of patients treated with Femara and 30 mg of temsirolimus.
- Adverse effects of treatment with temsirolimus included hyperglycemia (high blood sugar), hypertension (high blood pressure), and back pain.
The researchers concluded that compared to treatment with Femara alone, treatment with Femara plus the higher-dose of temsirolimus improved rates of cancer stabilization and survival without cancer progression in postmenopausal women with advanced, hormone-receptor-positive breast cancer. Toxicity of this treatment was acceptable. A phase III randomized trial is planned to compare Femara plus temsirolimus to Femara plus placebo.
Reference: Baselga J, Roché H, Fumoleau P, et al. Treatment of postmenopausal women with locally advanced or metastatic breast cancer with letrozole alone or in combination with temsirolimus: a randomized, 3-arm, phase 2 study. Program and abstracts of the 28th Annual San Antonio Breast Cancer Symposium; December 8-11, 2005; San Antonio, Texas. Abstract 1068.
Related News:Temsirolimus Promising for Treatment of Breast Cancer, Mantle Cell Lymphoma, and Glioblastoma (8/23/2005)
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