New Form of Fiber Fights Cancer
Human Trials Under Way for Citrus-Skin Derivative
Jan. 28, 2003 -- A new form of fiber fights tumors in animals. Early human trials show promise, but experts warn against using the fiber -- now available as a dietary supplement -- until more is known.
The fiber is called modified citrus pectin -- developed from the skin of citrus fruit. Everyday pectin is used to thicken many drugs, foods, and cosmetics. It's the ingredient that makes jellies jell. Pectin is made up of long strings of sugar. That makes it very interesting to researchers, who've only recently begun to understand the many complex roles sugars play in the body.
Avraham Raz, PhD, director of the tumor progression and metastasis lab at Detroit's Barbara Ann Karamanos Cancer Institute, became interested in the way cancer cells clump together to form tumors. He found that this clumping needed sticky sugars -- and that pectins can keep these sugars from sticking. Normal pectins won't work in the blood stream. But Raz's team found a way to alter pectin so that it could be digested and enter the blood. And that's not all.
In a recent issue of the Journal of the National Cancer Institute, Raz and colleagues showed that these modified citrus pectins cut the size of tumors in mice with implanted human breast and colon cancers.
"We give these soluble pectins to mice in their drinking water," Raz tells WebMD. "When we give them this drug they have remarkably diminished tumors and [spreading of cancer]."
This is a radically different kind of cancer treatment. Current chemotherapies kill tumor cells. The modified citrus pectins don't do this. Instead, they keep tumor cells from attaching to one another or to the walls of blood vessels. This keeps the cancer cells from gathering into tumors. It keeps them from spreading. And it eventually starves existing tumors by keeping them from growing new blood vessels.
Patent rights to the modified citrus pectin were sold to GlycoGenesys Inc., in Boston. The firm started human trials in patients with pancreatic and colon cancer that did not get better with conventional treatment. In October 2002, they announced results from a small trial in which 20 patients with pancreatic cancer got low doses of the drug, now known as GCS-100. The drug showed some activity in about a third of the patients, although only two had significant reductions in tumor size.
"GCS-100 was well tolerated and there were early signs of clinical activity in one of the two patients treated at our clinic," stated Corliss Newman of the University of Rochester Medical Center in a GlycoGenesys news release. "I await further findings of expanded clinical trials in the future aimed at determining a safe and efficacious dose of GCS-100."
Meanwhile, at least one other company is making a form of modified citrus pectin. EcoNugenics Inc. in Santa Rosa, Calif., sells it as Pectasol. A small clinical trial led by Mark Scholz, MD, of Healing Touch Oncology in Marina del Rey, Calif., is studying whether the supplement can help prevent recurrence of prostate cancer after surgery.