Background: T-20 is the first of a new class of antiretrovirals called HIV-1 fusion inhibitors and is in phase III trials. Prior studies focused on the use of T-20 in highly treatment-experienced patients. T20-206 enrolled less-experienced, NNRTI-naïve patients.

Methods: 71 protease inhibitor (PI)-experienced patients were randomized to either the fixed antiretroviral (ARV) regimen (A [N=19]: abacavir 300 mg BID, amprenavir 1200 mg BID and low-dose ritonavir 200 mg BID, and efavirenz 600 mg qd) or 1 of 3 T-20 treatments plus fixed regimen (B [N=16]: 50 mg BID [45 mg deliverable]; C [N=20]: 75 mg BID [67.5 mg deliverable]; D [N=16]: 100 mg BID SQ [90 mg deliverable]). T20-206 was not powered for efficacy differences, and combined T-20 results are therefore also included.

Results: Observed change from baseline in HIV-1 RNA (log₁₀) was: A - 1.87, B - 2.10, C - 2.62, D - 2.39. Intent-to-treat analysis of the percentage of patients reaching <400 C/mL HIV-1 RNA was 37% (7/19) in the control arm and 55% (28/51) in the combined T-20 group and for patients reaching <50 C/mL was 37% (7/19) in control and 47% (24/51) in the combined T-20 group. At week 48, the observed median CD4 + cell increase was: A +90, B +92, C +147, D +124, and combined T-20 increase was +132 cells. Injection site reactions (ISR) occurred in 68% of all patients receiving T-20; over 86% of ISRs were mild to moderate, and 3 patients (6%) discontinued because of ISRs. Besides ISRs, there were no major differences between control and T-20 groups in clinical or laboratory safety.

Conclusions: When NNRTI-naïve patients failing PI therapy received a fixed ARV regimen containing an NNRTI, the addition of T-20, a new class of ARV, to the regimen was well-tolerated and improved virologic and immunologic response over the ARV regimen at 48 weeks.