Treatment with two monoclonal antibodies can maintain the suppression of HIV-1 and reduce viral load in the absence of antiretroviral therapy (ART), report two small phase 1b clinical trials published this week in Nature and Nature Medicine.
Individuals with an HIV-1 infection require lifelong ART to suppress the virus, and interruptions to treatment can cause the reactivation of viral reservoirs. Previous studies have suggested that potent, broadly acting monoclonal anti-HIV-1 antibodies could represent an alternative to ART in neutralizing HIV-1.
Michel Nussenzweig and colleagues evaluated the efficacy of two monoclonal anti-HIV-1 antibodies (3BNC117 and 10-1074) to maintain viral suppression and reduce viral load (the amount of circulating viruses in the bloodstream) in two phase 1b clinical trials.
In the trial published in Nature, 15 participants received three infusions of the combined antibody therapy at three-week intervals after discontinuing ART. Four participants were excluded from the analysis, because they had a viral load that was too high after stopping ART. Antibody therapy was associated with maintenance of viral suppression for a median of 21 weeks (ranging from 5 to over 30 weeks).
In the trial published in Nature Medicine, seven participants with viruses in the bloodstream, who had not received ART, were administered either one or three infusions of the combined antibody therapy over a one-month period. This resulted in a reduced viral load that persisted for 3 to 16 weeks depending on the initial viral load and viral sensitivity of the participant.
The antibody therapy was generally well-tolerated by participants in both trials. However, the presence of antibody-resistant viruses or higher viral load seems to reduce the effectiveness of the therapy. The authors conclude that the combination of these two antibodies can suppress HIV-1 in the absence of ART in individuals with antibody-sensitive viruses, although larger trials are required to confirm these findings.