Nov. 9, 2000 (Amsterdam, Netherlands) -- Researchers gave a thumbs-up to one of the most eagerly awaited cancer drugs -- a genetically engineered protein that may prevent tumors from developing a blood supply and thriving.
The drug, called endostatin, interferes with the ability of small tumors to recruit cells to build blood vessels. Without those blood vessels, the cancer can't grow or spread to other parts of the body.
But while the studies showed that endostatin was not harmful and did have some cancer-fighting activity, doctors cautioned that even in the best scenarios, endostatin will not reach the nation's pharmacies or hospitals for at least eight years. The preliminary studies were announced here at a meeting of cancer experts.
On all fronts, endostatin succeeded, the researchers say, but most importantly, in the area of safety. "If you are going to have a drug that has to be taken for long periods of time -- and that is probably going to be the case with endostatin -- it cannot have serious side effects," says James Thomas, MD, assistant professor of medicine at the University of Wisconsin Medical School in Madison.
No significant side effects were seen in any of the 61 patients in the three studies, two of them sponsored by the National Cancer Institute and the third sponsored by drug manufacturer EntreMed of Rockville, Md.
As far as fighting cancer goes, one of the Houston patients, a 58-year-old man with malignant melanoma, experienced some reductions in skin tumors. And another patient achieved more than a 50% reduction in a head and neck tumor. Researchers from one of the other studies also reported two minor responses to the drug.
Researchers will tweak existing studies, and new ones will get under way. In fact, the University of Amsterdam will begin a study next week in which patients will wear an infusion pump that continuously delivers the drug.
All the patients in the endostatin study were suffering from end-stage cancer, says James Abbruzzese, MD, professor of medicine at the University of Texas M.D. Anderson Cancer Center in Houston. They all had progressive disease, and none were on any other active medication. All had taken one to 10 previous regimens of anticancer drugs, but the therapies failed to stop disease.