T-20 blocks HIV fusion with T-cells Credit: Courtesy of Trimeris, Inc.

Data presented at the recent European Conference on Clinical Aspects and Treatment of HIV Infection in Athens holds promise that medications being developed to combat multi-drug resistant HIV are nearing the market. The most recent analyses show that around 25% of patients undergoing antiretroviral therapy have developed multi-drug resistant HIV, and that the overall prevalence of resistance is growing (Nature Med. 7, 1016; 2001).

Phase II trials of T-20, a fusion inhibitor developed by North Carolina-based biotech company, Trimeris, reduced viral load by at least 10-fold in 56% of patients receiving treatment. Results from Phase III studies are expected in the Spring.

T-20 targets HIV as its membrane fuses with the membrane of a host cell—a critical step in viral entry. Trimeris is developing a second-generation drug (T-1249) which is roughly two years behind T-20 in the development pipeline. Because T-20 and T-1249 are small peptides that target the viral protein gp41, the differences in their resistance profiles suggest that engineering changes to peptide drugs may provide a rapid means of responding to new waves of viral resistance. In addition, preliminary evidence suggests that fusion inhibitors and other inhibitors of viral entry, such as compounds that block virus-receptor interactions, may act synergistically.