A new drug may stop the spread of lung cancer by blocking an enzyme that prevents cancer cells from dying.

Early tests of the drug in mice show that the active ingredient, a compound called GRN163L, works quickly and may eventually be useful after surgery or chemotherapy/radiation therapy to prevent any missed cancer cells from spreading.

Researchers say it's the first time that the drug has been shown to work in animals. Human trials are planned.

The results appear in the September issue of the journal Cancer Research.

Screening, Treating & Surviving Lung Cancer

New Lung Cancer Drug Passes First Hurdle

Lung cancer is the leading cause of cancer death. Researchers say survival rates for lung cancer are poor because the disease spreads quickly; sometimes the disease is already advanced at the time of diagnosis.

Previous studies of the drug in the lab have shown that it blocks an enzyme called telomerase that prevents cells from dying and is associated with the spread of most types of cancer.

In normal cells, the end of the chromosomes, known as telomere, becomes shorter and shorter as the cells divide and age. When they reach a certain length, the cells stop dividing and die. But in cancerous cells, telomerase kicks in and keeps the telomeres the same length, allowing them to divide and multiply indefinitely.

Researchers say telomerase works by binding to DNA and keeping the chromosome from getting shorter. But GRN163L matches a stretch of DNA on the chromosome that prevents the enzyme from binding.

In the study, researchers injected human lung cancer cells into the tails of mice and found that GRN163L blocked the growth of the tumors over the course of several months. The higher the dose of the drug, the fewer tumors there were.

Researchers say the results suggest that this enzyme-blocking action occurred at doses that would be reasonable for human treatment. But the drug may not work in people in whom lung cancers have already begun to spread.

The FDA recently approved human trials of the drug based on the results of this research.

Better Predictor of Lung Cancer Survival?

By Jennifer Warner, reviewed by Brunilda Nazario, MD

SOURCES: Dikmen, Z. Cancer Research, September 2005; vol 65: pp 1-8. News release, University of Texas Southwestern Medical Center.