HIV Drug Might Fight Cancer

Repositioning approved drugs could speed development of new therapies, researchers say.

By Steven Reinberg
HealthDay Reporter
Saturday, September 1, 2007; 12:00 AM

Copyright © 2007 ScoutNews, LLC. All rights reserved.

SATURDAY, Sept. 1 (HealthDay News) -- A drug used as part of a regimen to treat HIV also appears to kill cancer cells, researchers from the U.S. National Cancer Institute report.

Based on this new finding, the HIV protease inhibitor nelfinavir is being used in a phase I clinical trial to determine what might be the safest and most effective dose for cancer patients. This strategy of finding new uses for existing drugs could have a major impact on treating cancer and other diseases, the researchers added.

"This could be a new approach to finding cancer drugs and cut the time for getting them approved," said lead researcher Dr. Phillip A. Dennis. "Repositioning drugs that are already FDA-approved could accelerate the development of new cancer therapies."

The researchers hit upon the idea of testing nelfinavir and other protease inhibitors as cancer drugs, because these drugs block Akt, a protein essential for the development of many types of cancer, including non-small cell lung cancer.

The report is published in the Sept. 1 issue of Clinical Cancer Research.

In experiments with mice, Dennis' team tested six protease inhibitors on non-small cell lung cancer and on 60 human cancer cell types from nine different kinds of malignant tissue.

At doses that are safe in HIV-infected patients, three of the drugs, nelfinavir, ritonavir and saquinavir, blocked growth of non-small cell lung cancer and every other cancer cell type tested, the researchers found.

However, nelfinavir was the most effective of all the drugs tested. It caused cancer cells to self-destruct or become stressed to the point of dying, Dennis said.

In addition, nelfinavir inhibited the growth of both drug-sensitive and drug-resistant breast cancer cells, indicating that it could be used to fight cancer cells that are resistant to common chemotherapy drugs. Nelfinavir may also be able to overcome resistance to radiation, the researchers reported.

Dennis noted that low doses of nelfinavir are used in treating HIV, and even at those low doses, the drug is effective against cancer. The current phase I trial will test higher doses to find the most effective dose with the fewest harmful side effects, he said.