Antibody infusions suppress HIV

HIV infection can be kept in check with antiretroviral therapy, but treatment has to continue for life or the virus quickly gets out of control. Recent research from the Rockefeller University in New York shows the potential of neutralising antibody infusions to manage HIV when normal treatment is stopped.

The new study assessed infusions of a broadly neutralising antibody, 3BNC117, in people with established, but stable and treated, HIV infection. The antibody has been shown to be particularly potent and effective at reducing HIV levels after a single dose, but this is the first time it has been given in a series and assessed for more lasting effects.

Published in the journal Nature last week, the study compared two small groups of participants, both given the antibody. The first group (Group A, six men) were given two antibody infusions three weeks apart, and the second group (Group B, six men and one woman) were given up to four antibody infusions two weeks apart. Treatment was stopped for all participants two days after the first dose of antibody, with virus carefully monitored and treatment restarted if HIV reappeared.

The antibody infusions were safe and well-tolerated in recipients, and were able to control HIV for a limited period. In Group A, there was an average of 6.7 weeks between the first antibody dose and re-emergence of virus; and in Group B, HIV re-emergence came an average 9.9 weeks after the first antibody dose. Past studies show that simply stopping HIV treatment results in re-emerging virus in only 2.6 weeks, so the antibody infusions clearly delay the virus from coming back. Importantly, the rebound virus that was found in Group A participants was resistant to 3BNC117, while the rebound virus in Group B participants was still mostly sensitive. This suggests that the less intensive course of neutralising antibody (Group A) gave the advantage to virus that is not targeted by the 3BNC117 antibody, while the more intensive course of antibody dosing (Group B) was more effective at controlling all HIV.

While promising, these results also point to a number of challenges that remain before an effective alternative to antiretroviral drugs is available. The trial participants were hand-picked to have virus that would be effectively targeted by the antibody; only 11% of potential participants were found to be completely sensitive, although a further 54% showed a useful degree (if not complete) sensitivity. The infusions were better able to control rebound virus when given at 2-week rather than 3-week intervals, but longer intervals between interventions would be preferable to be a viable alternative to antiretroviral treatment. And of course, a more long-term effect would be critical. As lead researcher, Dr Michel Nussenzweig states “In my dreams, it’s like a flu shot. You give it once a year”.

Read the full article here

antibody clinical trial treatment interruption