Researchers hope antibody studies will pave way for HIV vaccine

The path for a cure or vaccine for HIV is littered with disappointments – much-hyped treatments or trials have ultimately ended in failure.

Today, however, the HIV research community is more hopeful, especially in lieu of PrEP – pre-exposure prophylaxis – the use of the antiretroviral drug Truvada to prevent HIV infection. With PrEP, HIV-negative individuals take a daily dose of Truvada to halt HIV transmission, and the drug is more than 99 percent effective at preventing HIV when taken daily.

Therein, however, lies the rub: PrEP requires daily adherence.

Flush on the heels of PrEP is a major new, multi-continent trial that will test a lab-created antibody to determine if it is effective in preventing HIV transmission.

The antibody was discovered in an HIV-infected individual who was able to control HIV infection without medication. Replicated in a lab, researchers will inject a solution containing the antibody into HIV-negative men and transgender individuals who have sex with men through an IV, then monitor whether infections occur.

The new study is called AMP, for antibody-mediated prevention.

“This is landmark study,” said Shobha Swaminathan, an infectious disease specialist who is part of the study. “It is the first study of this magnitude to see whether an antibody infusion can help prevent new HIV infections. If it proves effective, it could potentially pave a way for developing a vaccine for HIV infection.”

Typically, vaccines introduce a biological agent that stimulates the body’s immune system to recognize and fight off a particular disease. Many vaccines spark the body to create antibodies.

In AMP, patients recruited for the study will receive transfusions of saline solution including the antibody once every eight weeks. The trial will continue for roughly two years.

AMP is not a test for a vaccine. The antibody being studied dissipates over time. The hope, however, is that scientists can find antibodies that prevent HIV from replicating, and eventually create a vaccine that induces the body to produce antibodies that prevent HIV infection.

The study will recruit 2,700 men and transgender individuals whose sexual partners are men. In addition to being offered the antibody IV, participants will be counseled on safer sex practices and offered PrEP. Those already taking PrEP are not ineligible for the study.

The AMP study isn’t the only study looking at options for HIV prevention. Researchers are also currently testing long-lasting injectable medication, also administered about once every two months. The drug currently being tested is called cabotegravir and is owned by ViiV Healthcare. Cabotegravir has performed well in safety studies and animal testing.

Additionally, researchers are currently recruiting participants to test another iteration of Truvada. A study on non-human primates found the drug 100% effective at preventing HIV, but a second study suggested blood levels of the primary HIV-fighting drug in the body might be too low to be effective.

Gilead Sciences, the maker of Truvada, will soon be testing a modified version of the drug that has fewer reported side effects. Results from that study are expected in 2020.

Roughly 45,000 people contract HIV in the United States every year. Worldwide, roughly 37 million people are living with HIV. Most live in sub-Saharan Africa, where many of the AMP test sites are located.

When first recognized in 1981, HIV was usually fatal; today, it can typically be treated – but not cured – with a single daily pill that combines several anti-retroviral drugs.

To find out more about AMP, or to volunteer for the study, visit ampstudy.org.