Some cancer researchers say the drugs are the most exciting treatment that they have ever seen.
But then they temper their enthusiasm with caution, noting that the history of cancer treatments is full of high expectations followed by dashed hopes when drugs with remarkable effects in animals are tested in people. Still, the National Cancer Institute has made the drugs its top priority, said Dr. Richard D. Klausner, the director. The new drugs, angiostatin and endostatin, work by interfering with the blood supply tumors need. Given together, they make tumors disappear and not return. The data were remarkable.