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The additional 48-week optional treatment extension of the T-20 versus Optimized Regimen Only (TORO) studies evaluated long-term safety and efficacy of enfuvirtide (ENF) through week 96 in patients receiving ENF plus optimized background (OB) and patients switching to ENF plus OB from OB alone. Patient randomization was 2:1 to ENF plus OB (n = 663) and OB (n = 334), of which 89.7% and 89.8% were male, 89.3% and 88.6% were Caucasian, and median age was 41 and 42 years, respectively. HIV risk factors were comparable between the ENF plus OB and OB groups with the major factors being 65.2% versus 66.2% homosexual contact, 17.8% versus 19.8% heterosexual contact, 4.1% versus 4.8% bisexual contact, respectively, and 6.9% injection drug use in both groups. OB patients were allowed to switch to ENF plus OB at virologic failure before week 48 and required to switch at week 48 to continue in the study (n = 230). Efficacy and safety assessments were conducted for each group. At week 96, 55% of ENF plus OB subjects completed the study and 26.5% achieved a viral load of less than 400 copies per milliliter (17.5% achieved less than 50 copies per milliliter). Viral load and CD4 mean change from baseline was -2.1 and -1.1 [log.sub.10] HIV-1-RNA copies per milliliter and +166 and +116 CD4 cells/[mm.sup.3] for ENF plus OB and switch patients, respectively. No new ENF-related safety issues emerged in weeks 48-96. Injection site reactions led to discontinuation in 7% and 10% of ENF plus OB and switch patients, respectively. In conclusion, these data demonstrate durable efficacy and safety of ENF over 96 weeks and that early use of ENF in combination with other agents for the treatment of antiretroviral-experienced HIV-infected subjects is beneficial.

The analysis of pooled safety data from the pivotal phase three T-20 Versus Optimized Background Regimen Only (TORO) trials indicates that enfuvirtide is a well-tolerated antiretroviral agent with a maintained safety profile over 48 weeks in treatment-experienced HIV-1-infected adults. It is found that the rates of other adverse agents favored enfuvirtide or were generally comparable between treatments.

Exploratory analyses to compare treatment effects between the enfuvirtide and control groups by different factors after 48 weeks that were carried out are discussed. It was demonstrated that the efficacy to enfuvirtide is durable plus optimized background over 48 weeks.

A randomized, open-label, phase 3 study of enfuvirtide (T-20), a human immunodeficiency virus type 1 (HIV-1) fusion inhibitor was conducted through the T-20 vs. Optimized Regimen Only Study 1 (TORO 1). It was concluded that the addition of enfuvirtide to an optimized antiretroviral regimen provided significant antiretroviral and immunologic benefit through 24 weeks in patients who had previously received multiple antiretroviral drugs and had multidrug-resistant HIV-1 infection.

Background: Antiretroviral tolerability is a critical factor contributing to treatment outcome. The T-20 Versus Optimized Background Regimen Only (TORO) studies assessed the safety and efficacy of enfuvirtide in treatment-experienced HIV-1-infected patients., Methods: A total of 997 patients were randomized at a 2:1 ratio to an optimized background antiretroviral regimen plus enfuvirtide (n = 663) or an optimized background regimen alone (control group; n = 334). Control patients could switch to enfuvirtide on virologic failure., Results: In total, 26.5% of patients randomized to enfuvirtide and 36.6% to the control group discontinued study treatment before week 48; the percentage of patients withdrawn for safety reasons (including adverse events [AEs], deaths, and laboratory abnormalities) was 14.0% in the enfuvirtide group and 11.6% in the control group. Injection site reactions (ISRs) occurred in 98% of enfuvirtide patients and led to treatment discontinuation in 4.4%. Treatment-related (defined as possibly, probably, or remotely) AE rates per 100 patient-years were lower with enfuvirtide (96.2) than in the control group (149.9); diarrhea, nausea, and fatigue, the most frequently reported AEs, were significantly less frequent with enfuvirtide than in the control group. Pneumonia was significantly more frequent in patients treated with enfuvirtide (6.7 vs. 0.6 events per 100 patient-years), although the incidence was within expected ranges for this population. Lymphadenopathy was also higher in enfuvirtide-treated patients (7.1 vs. 1.2 events per 100 patient-years) for control patients., Conclusion: The addition of enfuvirtide to an optimized background regimen does not exacerbate AEs commonly associated with antiretrovirals. ISRs limited treatment in <5% of patients.