The Ixempra chemotherapy drug was approved for breast cancer patients whose tumors are resistant or not responsive to certain other meds. The approval is a turning point for the drugmaker, which was once a leader in cancer treatments, but has fallen behind in recent years.

The new med could generate annual sales of $500 million by 2012, according to Reuters. An estimated 160,000 women, and a relatively small number of men, in the US are diagnosed with breast cancer each year. About 40,000 die of the disease despite treatment with leading current drugs such as Bristol’s older Taxol, Sanofi-Aventis’ Taxotere and Roche’s Xeloda.

The approval was based on two multi-center, multinational trials which included 878 patients with spreading or locally advanced breast cancer, and evaluated the drug alone and in combination with capecitabine. You can read a little about the clinical trials in the Bristol-Myers statement.