FDA approves Bayer drug for rare gastrointestinal tract cancer WASHINGTON (Reuters) - The U.S. Food and Drug Administration said on Monday it has approved Bayer AG's drug Stivarga for the treatment of a rare type of gastrointestinal tract cancer. Stivarga is already approved to treat colon cancer that has progressed after prior treatment or that has spread to other parts of the body. Bayer will now also be able to market the drug as a treatment for gastrointestinal stromal tumors (GIST). Stivarga, known chemically as regorafenib, was tested in 199 patients with GIST that could not be surgically removed and had progressed after treatment with other therapies. Patients taking Stivarga had a delay in tumor growth progression that was on average 3.9 months later than patients given a placebo. Reporting By Toni Clarke in Washington; editing by John Wallace