Clinical trial data released by pharmaceutical company Boehringer Ingelheim at the 44th Interscience Conference on Antimicrobial Agents and Chemotherapy in Washington, D.C., on its experimental protease inhibitor tipranavir show that the drug is effective in treating HIV that has developed resistance to other protease inhibitors. Twenty-four-week data from a Phase III clinical trial of the drug show that a greater percentage of treatment-experienced HIV patients achieved a significantly higher treatment response to a tipranavir-based regimen than to other protease inhibitor-based regimens. About 34.7% of the treatment-experienced patients receiving tipranavir in the clinical trial reduced blood-based viral loads to under 400 copies after 24 weeks of treatment, compared with just 16.5% of those taking other protease inhibitors. Study subjects taking tipranavir also had greater increases in CD4-cell counts than those taking other protease inhibitors.
Tipranavir is a nonpeptide drug, unlike other protease inhibitors, and its unique chemical makeup allows it to remain effective even for patients resistant to other drugs in its class, company officials say. Tipranavir is designed to be taken with a low booster dose of the protease inhibitor Norvir. Boehringer Ingelheim submitted tipranavir to the Food and Drug Administration for marketing approval in late October. The company is seeking accelerated review status for the drug, which would guarantee a decision by the FDA within six months. Company officials hope to have the drug on the market by the middle of 2005.