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Antiviral Activity of Single-Dose PRO 140, a CCR5 Monoclonal Antibody, in HIV-Infected Adults
Background.
The current goal of human immunodeficiency virus type 1 (HIV-1) therapy is to maximally suppress viral replication. Securing this goal requires new drugs and treatment classes. The chemokine receptor CCR5 provides an entry portal for HIV-1, and PRO 140 is a humanized monoclonal antibody that binds to CCR5 and potently inhibits CCR5-tropic (R5) HIV-1 in vitro.
Methods.
A randomized, double-blind, placebo-controlled, dose-escalating study was conducted in 39 individuals with HIV-1 RNA levels ⩾5000 copies/mL, CD4+ cell counts ⩾250 cells/µL, no antiretroviral therapy for 3 months, and only R5 HIV-1 detectable. Cohorts were randomized 3:10 to receive placebo or doses of PRO 140 of 0.5, 2, or 5 mg/kg. Subjects were monitored for 58 days for safety, antiviral effects, and serum concentrations of PRO 140.
Results.
PRO 140 was generally well tolerated and demonstrated potent, rapid, prolonged, and dose-dependent antiviral activity. Mean reductions in HIV-1RNAlevel of 0.58 log10, 1.20 log10 (P = .0002) and 1.83 log10 (P < .0001) were observed for the 0.5-, 2-, and 5-mg/kg dose groups, respectively. Reductions in mean viral load of ⩾10-fold were observed within 4 days and persisted for 2-3 weeks after treatment.
Conclusions.
This trial established clear proof of concept for PRO 140 as a potent antiretroviral agent with extended activity after a single dose.
Trial registration.
ISRCTN Register: ISRCTN45537485
Maraviroc for previously treated patients with R5 HIV-1 infection
Background CC chemokine receptor 5 antagonists are a new class of antiretroviral agents.Methods We conducted two double- blind, placebo- controlled, phase 3 studies - Maraviroc versus Optimized Therapy in Viremic Antiretroviral Treatment- Experienced Patients ( MOTIVATE) 1 and MOTIVATE 2 - with patients who had R5 human immunodeficiency virus type 1 ( HIV- 1) only. They had been treated with or had resistance to three antiretroviral- drug classes and had HIV- 1 RNA levels of more than 5000 copies per milliliter. The patients were randomly assigned to one of three antiretroviral regimens consisting of maraviroc once daily, maraviroc twice daily, or placebo, each of which included optimized background therapy ( OBT) based on treatment history and drug- resistance testing. Safety and efficacy were assessed after 48 weeks.Results A total of 1049 patients received the randomly assigned study drug; the mean baseline HIV- 1 RNA level was 72,400 copies per milliliter, and the median CD4 cell count was 169 per cubic millimeter. At 48 weeks, in both studies, the mean change in HIV- 1 RNA from baseline was greater with maraviroc than with placebo: - 1.66 and - 1.82 log(10) copies per milliliter with the once- daily and twice- daily regimens, respectively, versus - 0.80 with placebo in MOTIVATE 1, and - 1.72 and - 1.87 log(10) copies per milliliter, respectively, versus - 0.76 with placebo in MOTIVATE 2. More patients receiving maraviroc once or twice daily had HIV- 1 RNA levels of less than 50 copies per milliliter ( 42% and 47%, respectively, vs. 16% in the placebo group in MOTIVATE 1; 45% in both maraviroc groups vs. 18% in MOTIVATE 2; P< 0.001 for both comparisons in each study). The change from baseline in CD4 counts was also greater with maraviroc once or twice daily than with placebo ( increases of 113 and 122 per cubic millimeter, respectively, vs. 54 in MOTIVATE 1; increases of 122 and 128 per cubic millimeter, respectively, vs. 69 in MOTIVATE 2; P< 0.001 for both comparisons in each study). Frequencies of adverse events were similar among the groups.Conclusions Maraviroc, as compared with placebo, resulted in significantly greater suppression of HIV- 1 and greater increases in CD4 cell counts at 48 weeks in previously treated patients with R5 HIV- 1 who were receiving OBT. (ClinicalTrials. gov numbers, NCT00098306 and NCT00098722.)