BREAST CANCER DRUG STUDIED : PATIENTS ENROLLED AFTER LAB ACCIDENT SHOWS PROMISING EFFECT.

Byline: Keith Stone Daily News Staff Writer

UCLA doctors began enrolling patients Monday in a study of a promising new breast cancer drug that researchers discovered through a fluke in the laboratory.

The drug, TNP-470, is designed to prevent the formation of microscopic blood vessels that cancerous tumors need to grow and move throughout the body, said Dr. Mai Nguyen, principal investigator for the study.

Tests have shown that when a tumor is deprived of blood, it shrinks to a harmless size and won't spread, said Nguyen, an assistant professor at the University of California, Los Angeles Medical School.

``We're excited and hopeful this will be the magic drug - but we have to prove it first,'' she said. The study's co-investigators are Dr. John Glaspy of Northridge and Dr. Susan Love of Pacific Palisades.

Success against breast cancer with the intravenously administered TNP-470, Nguyen said, would hold broad promise for treating other metastatic tumors - those prone to spreading.

Cancerous tumors can spread through the lymphatic system and bloodstream, but Nguyen said studies on animals show that TNP-470 seems to work against both modes of transmission.

``The end result is we just don't see spread. We assume it works on both,'' Nguyen said.

Side effects have been minimal. The drug would not affect other blood vessels, Nguyen said, because adults typically form no new ones, except under certain conditions, including cancer, diabetes and pregnancy.

UCLA's Jonsson Comprehensive Cancer Center is alone nationwide in conducting the safety and efficacy test, although other research institutions may join the study.

On Monday, UCLA doctors began accepting applications from women who want to take part in the three-month study. The study will include 100 women who are 18 or older and have metastatic breast cancer. They must be willing to receive chemotherapy or have gotten it within the past month and a half.

For more information, call Nguyen at [phone].

Thirty of the 100 patients will receive a placebo, although they will have undergone chemotherapy, the standard treatment for breast cancer.

Earlier studies of TNP-470 on humans and animals showed that the drug is safe and stops tumors from growing, if it doesn't shrink them, Nguyen said.

Unlike chemotherapy, which poisons tumors, TNP-470 focuses on restricting the growth of blood vessels without killing them, Nguyen said.

``This is a novel approach to cancer therapy,'' she said, adding, however, that the effect of the treatment is not permanent. ``We believe that eventually this drug, to be effective, must be given continually.''

The drug was developed by Dr. Donald Ingber and Dr. Judah Folkman, who was Nguyen's mentor at Harvard Medical School. Folkman pioneered the field of angiogenesis, the study of how new, microscopic blood vessels are formed.

Ingber discovered the substance that led to TNP-470 when fungus accidentally tainted blood vessel cells during an experiment. He noticed that the fungal contamination had stunted the growth of the cells.

Folkman and Ingber then isolated the ingredient in the fungus.

``We prepare our minds so when a chance incident like this happens,'' Nguyen said, ``we don't overlook it.''