Infusions of an anti-HIV antibody known as VRC01 were shown to be safe and maintained intended antibody concentrations in the blood of people living with HIV, according to two related studies by scientists at the National Institutes of Health (NIH) and the AIDS Clinical Trials Group (ACTG). The antibody modestly suppressed blood levels of HIV in people who stopped taking antiretroviral therapy (ART), but the delay in the reappearance of virus was not clinically significant. Findings from both studies, which received funding from the National Institute of Allergy and Infectious Diseases, part of NIH, appear in the Nov. 24 issue of the New England Journal of Medicine.
After receiving regular intravenous infusions of VRC01, participants in the NIH and ACTG studies experienced a reappearance of measurable HIV in the blood—or viral rebound—at a median of 39 and 28 days, respectively, after halting ART. Typically, HIV rebounds within about two weeks after interrupting therapy. These results indicate the antibody may have had a modest effect on temporarily controlling HIV.
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The NIH trial team, led by Anthony S. Fauci, M.D., Michael C. Sneller, M.D., and Tae-Wook Chun, Ph.D., gave HIV-infected volunteers intravenous infusions of VRC01 before the participants stopped their normal regimens of ART. Additional infusions were given at two and four weeks after halting ART and then at monthly intervals for up to 6 months. In a similar regimen, researchers at clinical sites at the University of Pennsylvania and the University of Alabama, led by Katharine J. Bar, M.D., and Pablo Tebas, M.D., of the ACTG and the Penn Center for AIDS Research, gave study participants VRC01 infusions one week prior to stopping ART and then every three weeks for up to three doses. The 23 participants evaluated in both studies tolerated the treatments well.
Researchers found that HIV isolated from study participants before and after experiencing viral rebound was not as susceptible to VRC01 as had been anticipated. Moving forward, to address the issue of viral resistance, researchers plan to investigate combinations of more potent anti-HIV antibodies as long-term antibody therapy for people living with HIV. Currently, other NIAID-supported researchers are also investigating the ability of VRC01 to prevent HIV infections in at-risk individuals who do not have HIV in the AMP Studies for HIV Prevention.