Research coming out of Rockefeller University indicates that two HIV-fighting antibodies, when combined, can help to suppress the dreaded virus for months, possibly with less reliance on daily drug use.
In the clinical studies, which were reported in Nature and Nature Medicine, the researchers made use of a combination of two broadly neutralizing antibodies (bNAbs). These were called 3BNC117 and 10-1074. They were found in “elite controllers,” people whose bodies were successful in fighting off HIV without any need for drugs.
It was observed that these natural antibodies have proteins on the surface of the virus as their targets. They make it easier for the body’s immune system to detect and get rid of the pathogen.
When it comes to the control of HIV infection, antiretroviral therapy (ART) is arguably the most effective. It has been convincingly shown in clinical settings as a very potent way of keeping the viral infection well under control.
But the story is different in the real world. Things are not as well controlled as they are in clinical trials. Patients can fail or forget to take their daily medications or not even have access to them. This creates room for the virus to gain strength while also increasing the likelihood of transmission.
There is no drug yet that can wipe the virus in its entirety. They merely suppress it and when patients fail to use their drugs regularly HIV levels rise.
The new research highlighting the potential of this HIV antibody combo is part of efforts to reduce dependency on daily pills, thereby safeguarding both individuals and communities. And the results suggest that this may be possible sometime soon.
The primary aim with bNAb therapy is to make it possible for patients to develop similar defense mechanism as elite controllers. It targets boosting the ability of the immune system to suppress the virus.
A particular quality that makes this approach particularly appealing is that it will be administered less frequently, compared to regular pills. These antibodies will work for longer in the body.
It was shown in earlier research that the use of a bNAb can help to reduce HIV levels in the blood. However, this effect does not last for a long time. The virus mutates after a while to render the antibody used against it ineffective.
This explains why the Rockefeller University researchers led by Professor Michel C. Nussenzweig decided on a two-pronged approach. They felt that when two antibodies are targeted against the virus from different angles the likelihood of resistance will reduce.
This combination treatment was first tested in animals. It was decided for evaluation in humans only after showing good potential in the animal studies.
Participants in the phase 1b trials with well-controlled viral load stopped using their antiretroviral medications. They were then given three infusions of the two anti-HIV antibodies for a period of six weeks.
The researchers observed that the treatment helped to suppress HIV among nine patients that were sensitive to the two antibodies. The viral loads of these subjects were kept under control through the treatment for an average of 21 weeks. In some patients, HIV suppression continued for more that 30 weeks as a result.
The safety profile of this antibody combination was also good. No overly distressing side effects were reported, with the most significant being mild fatigue in some of the patients.
The participants who were sensitive to the combination therapy did not develop the kind of resistance seen in patients treated with just one bNAb.
In the second trial whose results were published in the journal Nature Medicine, patients who had not received ART and so still had HIV actively circulating in their bloodstream were also treated with the combination therapy. This reduced their viral load for up to three months.
The main limitation right now is that not all cases of HIV infection are sensitive to these two bNAbs, according to the researchers. But they can be beneficial to more people when combined with antiretroviral drugs or other antibodies.