Pfizer breast cancer drug gets breakthrough label

Published on NewsOK Modified: April 10, 2013 at 12:18 pm •  Published: April 10, 2013

TRENTON, N.J. (AP) — Pfizer Inc. said Wednesday that its experimental pill for advanced, often deadly breast cancer has been designated as a breakthrough therapy by the Food and Drug Administration.

Pfizer shares jumped nearly 3 percent following the news.

The breakthrough designation, created under legislation enacted last summer to fund and improve operations of the FDA, is meant to speed up development and review of experimental treatments that are seen as big advances over existing therapies for serious diseases. Pfizer is working with the agency to determine exactly what research results it will need to apply for approval of the drug.

Palbociclib is being evaluated as an initial treatment for the biggest subgroup of postmenopausal women whose breast cancer is locally advanced or has spread elsewhere in the body. About 60 percent of women with such advanced breast cancer have tumors classified as ER+, or estrogen-receptor positive, but HER2-, or lacking an excess of the growth-promoting protein HER2.

Estrogen-receptor positive tumors have proteins inside and on the surface of their cells to which the estrogen hormone can attach and then fuel growth of cells. These tumors tend to grow slowly and can be fought with drugs that block estrogen's effects.

Meanwhile, about 80 percent of breast cancer tumor cells are HER2 negative. That means that unlike HER2 positive tumors, they don't produce too much of the HER2 protein, which makes tumors grow and spread more aggressively than in other breast cancer types.

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