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FDA Grants Palbociclib Accelerated Approval for Advanced Breast Cancer

, by NCI Staff

The Food and Drug Administration (FDA) has granted accelerated approval to palbociclib (Ibrance) for the initial treatment of breast cancer in postmenopausal women with metastatic disease. The approval is for the use of palbociclib in combination with the aromatase inhibitor letrozole.

Palbociclib is the first FDA-approved cancer drug that works by inhibiting cyclin-dependent kinase (CDK) 4 and 6, both of which are involved in regulating cancer cell division.

The approval of palbociclib is based on results from a randomized phase II trial that randomly assigned 165 postmenopausal women with ER-positive, HER2-negative breast cancer to receive either palbociclib plus letrozole or letrozole alone. The majority of the women (98 percent) had metastatic disease. Median progression-free survival was 20.2 months among the women who received palbociclib plus letrozole and 10.2 months in women treated with letrozole alone.

An accelerated approval is designed to hasten the availability of drugs that treat serious conditions and that fill an unmet medical need. These approvals are based on a surrogate endpoint, such as tumor shrinkage, that is believed to predict a clinical benefit but is not itself a definitive measure of clinical benefit.

Under an accelerated approval, the company is required to conduct studies, known as confirmatory trials, to confirm the anticipated clinical benefit—such as improved overall survival, reduction in pain, or improved function. If the confirmatory trial shows a clinical benefit, the FDA then grants traditional approval for the drug. If the confirmatory trial fails, the FDA could remove the drug from the market.

Pfizer, which manufactures palbociclib, is conducting a confirmatory phase III trial, called PALOMA-2, that is fully enrolled, according to a company news release. The trial is expected to be completed by October 2016.

“These are exciting results from a novel agent in an early-phase study,” said Jo Anne Zujewski, M.D., of NCI’s Division of Cancer Treatment and Diagnosis. “The accelerated approval mechanism allows patients earlier access to a very promising drug while not compromising the ability to obtain definitive results. This is good news for patients.”

More information on breast cancer therapies and recent clinical trial results are available on NCI’s Breast Cancer Topics page.

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