Experimental Therapy Suppresses HIV Infection

Treatment dramatically reduces viral load in blood.

A new generation of broadly neutralizing antibodies for the treatment of HIV caused a significant viral load reduction during a recent clinical study.

The study, published in Nature, evaluated the ability of a potent antibody, 3BNC117, to get ahead of the virus to reduce viral loads in the blood. 3BNC117 is part of a new wave of antibodies with the potential to potently battle a wide range of HIV strains.

"What's special about these antibodies is that they have activity against over 80% of HIV strains and they are extremely potent," co-first author Marina Caskey said in a press release.

3BN117 attacks the CD4 binding site of the HIV envelope, showing activity against 195 of 237 HIV strains.

Between 10 to 30% of people infected with HIV naturally produce broadly neutralizing antibodies after several years of infection. By the time this occurs, however, the virus has typically evolved to escape the potent antibodies.

Through isolating and cloning these antibodies, the researchers were able to treat HIV before it mutates. The antibodies were able to prevent or suppress infection in mouse and non-human primate models of HIV during prior studies, but these models are rough approximations of human infections, the study noted.

Because they have been genetically engineered to be susceptible to HIV, the mice lack an intact immune system, while the primates can only be infected with a simian version of the virus.

For the current study, uninfected and HIV-infected human patients received a single dose of 3BNC117 intravenously and were monitored for 56 days. At 30 milligrams per kilogram of weight, all 8 infected individuals treated with the highest dosage level experienced a 300-fold drop in viral load, as most of these patients reached their lowest viral load after a week of treatment.

The decreased viral load was dependent on the starting viral load of the patient and the sensitivity of the particular HIV strains to the antibody. Half of the patients who received the highest dose saw their viral loads remain below the starting levels at the end of the 8-week study period, as resistance to the experimental drug did not occur.

The researchers also believe the antibodies may be able to improve the immune response to better control HIV infection. Furthermore, the new generation of antibodies may be able to kill the viral reservoirs that are inaccessible to current antiretroviral drugs.

"In contrast to conventional antiretroviral therapy, antibody-mediated therapy can also engage the patient's immune cells, which can help to better neutralize the virus," co-first author Florian Klein said in a press release.