WASHINGTON (Reuters) - An early try at making a universal cancer vaccine seems to be safe, and shows some indication that it may even work, researchers at Geron Corp. said on Monday. The first few cancer patients immunized with the vaccine showed no bad reactions and in fact seemed to mount an immune response against their own cancers, the Menlo Park, California-based company said. The results are very preliminary but suggest the research approach is valid, Geron said in a statement. Geron shares rose slightly on the news, to $6.70 a share in mid-morning trading. Geron was scheduled to present...