The U.S. Food and Drug Administration has approved a first-of-a-kind breast cancer medication that targets tumor cells while sparing healthy ones, AP reported. The drug Kadcyla from Roche combines the established drug Herceptin with a powerful chemotherapy drug and a third chemical linking the medicines together. The chemical keeps the cocktail intact until it binds to a cancer cell, delivering a double-shot of anti-tumor poison. Cancer researchers say the drug may offer a clear advantage over older drugs because it delivers more medication with fewer side effects. The FDA approved the new treatment for about 20 percent of breast cancer patients with a form of the disease that is typically more aggressive and less responsive to hormone therapy. These patients have tumors that overproduce a protein known as HER-2. The approval will help Roche's Genentech unit build on the blockbuster success of Herceptin, which has long dominated the breast cancer marketplace. The drug had sales of roughly $6 billion last year. -- SPA