A new cancer drug may halt tumor growth by blocking the division of cancerous cells while leaving healthy cells alone, according to early tests in animals.

Researchers say if further studies confirm these results in humans, the experimental cancer drug may be a new way to offer highly targeted cancer treatment with few side effects.

The study suggests that the drug, known as ONO1910, works by zeroing in on a molecule called PLK1 that is known to play a critical role in the spread of cancer. The molecule drives normal cell division. High levels of it have been found in human cancer tumors and have been associated with more aggressive and deadly cancers.

Because cell growth regulation is awry in a cancer cell, a reasonable approach to cancer therapy is to develop drugs that block the function of a critical molecule that is required by a tumor cell to complete cell division, says researcher E. Premkumar Reddy, PhD, of the Temple University School of Medicine, in a news release.

The results of the study have prompted the researchers to test the experimental treatment in humans.

Experimental Cancer Drug Stops Tumor Cells

In the study, which appears in the March issue of the journal Cancer Cell, researchers tested the effects of ONO1910 on tumor growth in mice as well as human cancer cells in the lab.

“We found that ON01910 was a potent inhibitor of human tumor growth and also worked well with several existing cancer drugs, often inducing complete regression of tumors,” says Reddy. “Someday it might work either as a single drug or in combination with other drugs."

Researchers say the drug stops tumor cells from reaching normal, healthy cells in three ways.

“First, it blocks invasion, next it blocks angiogenesis [formation of new blood vessels needed for growth] and finally, it induces tumor cell death,” says Reddy. “It also appears to be very safe."

Researchers say the experimental cancer drug did not appear to affect normal, noncancerous human cells, which suggests that it would produce a low level of side effects.

The research was supported by grants from Onconova Therapeutics Inc.’s drug discovery program and the Fels Foundation.

By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: Gumireddy, K. Cancer Cell, March 2005; vol 7: pp 275-286. News release, Temple University. News Release, Cell Press.