AEGiS-WSJ: New Drug From Pharmacia May Fight Strains of AIDS

Important note: Information in this article was accurate in 1999. The state of the art may have changed since the publication date.

New Drug From Pharmacia May Fight Strains of AIDS

The Wall Street Journal - June 24, 1999
Michael Waldholz, Staff Reporter

In a laboratory study both hopeful and surprising, researchers found an experimental drug being developed by Pharmacia & Upjohn may be active against many strains of the AIDS virus that have developed resistance to existing drugs. If the new drug's potency holds up in human trials, the Pharmacia & Upjohn compound may someday become an unexpected and important new weapon in treating HIV, the AIDS virus. Prior to the release of the new scientific data Wednesday, no news about the new drug had been revealed by the company or by AIDS drug researchers.

The drug, called tripranavir, is expected to generate interest among AIDS doctors and patients, and even on Wall Street, because over the past year or so scientists have uncovered growing evidence that some AIDS medicines are losing their effectiveness as a result of rising viral resistance among treated patients. Also, some people are being infected with versions of the virus already resistant to some of the anti-HIV drugs.

In data released Wednesday at an international scientific meeting on AIDS drug resistance in San Diego, researchers from Pharmacia & Upjohn and others at Virco, a Belgian biotechnology company, report that tripranavir was able to block the action in test-tube experiments of many strains of HIV that are strongly resistant to four widely used AIDS drugs known as protease inhibitors.

Tests on 107 Strains

Tripranavir is also a protease inhibitor. But in the new study, Virco scientists tested tripranavir against 107 mutated versions of the virus found in HIV-infected people. The mutant strains are no longer susceptible to the four marketed protease inhibitor medicines, such as Merck & Co.'s Crixivan and Agouron Pharmaceuticals Inc.'s Viracept, the two best-selling drugs in the class. Only three of the strains tested were fully resistant to tripranavir, and eight other strains were mildly resistant to the drug, according to Brendan Larder, Virco's vice president of research, who presented the findings at the Third International Workshop on HIV Resistance and Treatment Strategies.

"We were shocked," Dr. Larder said in a telephone interview, noting that Virco's staffers conducted the experiments several times before they were certain of their findings, because the company previously hadn't found any other protease inhibitor active against so many resistant HIV strains.

Ferdinand Massari, a Pharmacia & Upjohn research executive, said in a telephone interview that the company had discovered tripranavir about 18 months ago as part of a research effort to find a protease inhibitor that works differently from the other drugs. Protease inhibitors block HIV replication by attaching to the so-called active site of the protease enzyme, a natural protein produced by the virus and critical to viral replication. The virus, however, can become resistant to the drugs if it is able to mutate and produces an active site with a shape into which the drug no longer can fit.

"There's reason to believe tripranavir is a more flexible chemical than the other drugs, allowing it to fit into the active site even when it changes shape," Dr. Larder said.

Pharmacia & Upjohn turned to Virco to test its drug because, over the past two years, Virco has developed a diagnostic test that can detect the genetic mutations that make HIV resistant to drugs.

Pharmacia & Upjohn, of Bridgewater, N.J., said it has only tested tripranavir in a small number of patients and hopes to begin expanded studies in patients resistant to existing drugs sometime later this year. The company said the new resistance data has given it impetus to aggressively develop the new medicine, but performing all necessary human tests to prove its effectiveness and safety still may take several years.
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Always watch for outdated information. This article first appeared in 1999. This material is designed to support, not replace, the relationship that exists between you and your doctor.

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