FDA Expands Use of Femara in Fight Against Breast Cancer

A drug shown to delay progression of advanced breast cancer for several months is likely to replace the current preferred treatment for American women.

The Food and Drug Administration last week approved the expanded use of Femara, which allows doctors to prescribe it first for their patients with late-stage breast cancer. The current standard therapy is tamoxifen.

A large international study of 907 post-menopausal women with advanced breast cancers found that Femara provided patients with a median time of 3.4 more months before tumors worsened than did tamoxifen.

“This will change practice,” predicted Dr. John Glaspy, medical director of outpatient oncology at the UCLA Jonsson Comprehensive Cancer Center. “It’s important, because instead of starting with tamoxifen in metastatic breast cancer, people may be more inclined, and should be more inclined, to start with Femara.”

Glaspy called those three months “a small advantage that would be a reason to start with Femara.”

Metastatic cancer is cancer that has spread through the body. There are no cures, only treatments, for breast cancer that has spread to other organs and tissues.

The Food and Drug Administration on Wednesday approved expanded use of Femara, the commercial name for letrozole. The FDA had previously approved Femara for use as an alternative when other hormonal treatments, such as tamoxifen, failed in women with advanced cancers.

Femara is among hormonal treatments that interfere with the hormone estrogen. Estrogen feeds the growth of about half of all breast cancers. Hormonal treatments are less toxic and generally longer-working than chemotherapy. Women with advanced breast cancer typically stay on tamoxifen for five years.

Femara belongs to a class of drugs called aromatase inhibitors. Unlike tamoxifen, which acts like a weak estrogen and competes with stronger and more harmful estrogens to lock onto the surface of breast cancer cells, Femara shuts off estrogen.

Even with the latest development, tamoxifen isn’t likely to be immediately knocked out of its top spot in the cancer drug market, Glaspy said, because Femara hasn’t yet been demonstrated effective for tamoxifen’s two biggest uses: prevention of breast cancer in women at high risk and prevention of breast cancer recurrence. Most women with tumors that are fed by estrogen take tamoxifen after breast surgery to prevent recurrence.

“The most recent, and in some views, the most important use of tamoxifen has been prevention of breast cancer in high-risk patients and this tells us nothing about that,” Glaspy said. He cautioned that women who are taking tamoxifen preventively because it can reduce their risk of developing an inherited form of breast cancer by 50% should not switch treatments.

The study made no findings about whether Femara improves survival, Glaspy noted.

“I don’t think it’s going to change the mortality of breast cancer,” he said, “or be a major advantage in making breast cancer less of a burden to the U.S. or the women who have it.”

The drug, manufactured by Novartis Pharmaceuticals Corp. of East Hanover, N.J., is comparable in price and has similar side effects to tamoxifen. Femara’s most frequently reported side effects were bone and joint pain, hot flashes, back pain, nausea and trouble breathing, the FDA said in its announcement.