Wang CY, et al. - Researchers examined the consequences of anti-CD4 antibody UB-421 on HIV-1 rebound following treatment interruption. They found that, in the absence of antiretroviral therapy (ART), UB-421 sustained virologic suppression (during the 8-16 weeks of study) in study participants.

Methods

• In this non-randomized, open-label, phase 2 clinical study, investigators evaluated the safety, pharmacokinetics, and antiviral activity of UB-421 monotherapy in HIV-infected subjects who underwent analytic treatment interruption.
• At the screening visit, all subjects had undetectable plasma viremia (< 20 copies of HIV RNA/mL).
• Subjects received eight intravenous infusions of UB-421 at a dose of either 10 mg/kg of body weight every week (Cohort 1) or 25 mg/kg every 2 weeks (Cohort 2) after discontinuation of ART.
• Time to viral rebound (≥ 400 copies/mL) was the primary outcome.

Results

• The study included 29 subjects: 14 in Cohort 1 and 15 in Cohort 2.
• UB-421 maintained virologic suppression (< 20 copies/mL) in all the participants during analytic treatment interruption, with intermittent viral blips observed in 28% of subjects.
• They did not observe plasma viral rebound to more than 400 copies/mL in subjects.
• Stable CD4+ T-cell counts were recorded throughout the study period.
• They reported rash (mostly of grade 1) as a frequent and transient adverse event; one subject discontinued the study drug due to rash.
• During UB-421 monotherapy, a reduction in the population of CD4+ regulatory T cells was also noted.