Short-term safety and antiretroviral activity of T-1249, a second-generation fusion inhibitor of HIV.

T-1249 is a 39-aa synthetic peptide that inhibits fusion of human immunodeficiency virus (HIV) to the host target cell. A 14-day open-label, phase 1/2 dose-escalation monotherapy study of the safety and antiretroviral activity of T-1249 was performed on 115 HIV-1-infected adults. At baseline, the majority of the patients had advanced HIV disease (baseline median CD4(+) cell count, 57 cells/microL) and had extensive pretreatment (i.e., pre-T-1249) experience with antiretroviral medications (median, 11 antiretroviral drugs). Patients received T-1249 monotherapy by subcutaneous injection, for 14 days, at doses ranging from 6.25 to 192 mg/day. T-1249 was generally well tolerated, and no dose-limiting toxicity was identified. Injection-site reactions were the most commonly reported adverse event (57%). Dose-dependent decreases in plasma HIV-1 RNA load were observed; the median maximum change from baseline across dose groups ranged from -0.29 log(10) copies/mL (95% confidence interval [CI], -0.43 to -0.05 log(10) copies/mL) for the lowest dose to -1.96 log(10) copies/mL (95% CI, -2.02 to -1.37 copies/mL) for the highest dose. These results indicate that T-1249 is a potent new therapeutic agent for HIV-1 infection.