Pharmaceutical Companies Release Study Results of New Antiretroviral Drugs at ICAAC Conference
The results of three studies of new antiretroviral drugs were released on Sunday and Monday by drug makers GlaxoSmithKline, Boehringer Ingelheim and Gilead at the Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington, D.C., the Wall Street Journal reports. The conference is the annual meeting of the American Society for Microbiology. New antiretroviral drugs are needed to fill the "treatment gap" left when patients develop drug-resistant strains of HIV, according to the Journal. About one in five HIV-positive patients are infected with drug-resistant virus, even if they have never taken antiretroviral medications, according to GSK research, the Journal reports (Chase, Wall Street Journal, 11/1). Summaries of the studies appear below:
- GSK's experimental antiretroviral known as Glaxo 873140 reduced the amount of HIV in patients' blood by more than 90% after 10 days and the drug's effectiveness improved with increases in dosage, Reuters reports. The drug belongs to a new class of medicines, known as CCR5 inhibitors, that block HIV before it enters human cells, rather than fighting it once inside the cells. These types of drugs may keep patients healthy for longer periods of time with fewer side effects than traditional antiretroviral therapies and may provide a new option for patients who have developed resistance to conventional HIV/AIDS drugs, according to Reuters (Reuters , 11/1).
- Boehringer's antiretroviral drug tipranavir reduced 41.5% of patients' viral load to a pre-defined level, compared with 22.3% of patients who were taking other protease inhibitor drugs, according to data from the RESIST-1 Phase III study of 620 patients, Reuters reports. Protease inhibitors work by blocking the action of an enzyme that cuts HIV proteins into the shorter sections that the virus needs to create copies of itself. Tipranavir, which is intended for patients who experience resistance to other drugs, could be launched by the middle of 2005 (Reuters , 11/1). Boehringer has applied for U.S. and E.U. approval to sell and market tipranavir, the company announced last week. The company is seeking accelerated evaluation in Europe and priority review from FDA, which could result in a decision in as few as six months (Kaiser Daily HIV/AIDS Report, 10/26).
- Gilead on Monday said that its experimental antiretroviral drugs Viread and Emtriva were more effective in interim clinical trials than GSK's Combivir, Reuters reports. Six-month results of Gilead's once-daily drugs, which were combined into a single pill called Truvada, showed that 87% of previously untreated patients maintained a "significant reduction" in HIV levels with the Viread/Emtriva regimen, compared with 78% of patients on the Combivir regimen, according to Reuters. The study of 509 previously untreated patients also showed that 9% of patients taking Combivir dropped out of the study because of side effects -- such as anemia, nausea and fatigue -- compared with 3% in the Viread/Emtriva group. "The convenience and tolerability of an antiretroviral regimen is increasingly important as patients remain on therapy for longer periods of time," Brian Gazzard, a study investigator, said. However, GSK said that the preliminary study results should be viewed with "caution" because the Gilead drugs have not been available for as long as Combivir and patients in the study knew which regimen they were taking, according to Reuters. "Combivir is a well-studied and well-understood drug with more than 40 clinical trials involving more than 12,500 patients since 1997," GSK Vice President Doug Manion said. Both treatment regimens in the study also included the antiretroviral drug efavirenz, which is marketed by Bristol-Myers Squibb (Reuters , 11/1).