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WEDNESDAY, September 26, 2018 – A combination of two anti-HIV antibodies may suppress the virus in some patients, even after stopping standard drugs, showed a preliminary test.
The researchers found that of the 11 HIV-infected patients who received the antibody combo, nine maintained complete suppression of the virus after dropping their drug treatment. The benefit generally lasted about five months.
The hope, according to the experts, is that therapy – or others like it – could one day release some patients from taking daily tablets to control the virus causing AIDS.
The "cocktails" of drugs used to treat HIV – what doctors call antiretroviral therapy (ART) – have changed the face of the epidemic in countries where they are widely available.
Drugs can drive HIV to undetectable levels in the blood, making the disease a manageable chronic disease.
"The current drugs are very effective," said Dr. Marina Caskey, one of the researchers on the new work. "They allow people to have a long and healthy life for the most part."
However, she adds, the treatment is daily and permanent. Drugs do not ban HIV and if a patient stops taking them, the virus comes back.
In addition, noted Caskey, the drugs cause side effects. In the long term, this includes increased risks of heart, kidney and liver disease, diabetes and bone loss.
Researchers are therefore trying to develop therapies that can send HIV into remission for prolonged periods. With antibody therapy, the vision is to give patients an infusion every three to six months, said Caskey, an associate professor at Rockefeller University in New York.
Specifically, research focuses on "largely neutralizing antibodies", or BNAbs. This means that they neutralize multiple strains of HIV.
Previous studies have tested unique BNAbs and found that the tactic did not work for long.
"When you give one, the virus can escape and change to become resistant [to the antibody]"Explained Caskey.
She and her colleagues felt that a two-fold antibody attack would be more effective, just like the drug combinations against the virus.
So they tested a combination of two bNAbs among people qualified as "elite controllers". They have HIV, but their immune system is able to control the virus without drugs.
In one study, researchers treated 11 patients whose HIV was under control with standard drugs. Tests showed that all seemed sensitive to both antibodies.
Patients stopped their anti-HIV drugs. Then, for six weeks, they received three infusions of antibodies. Overall, the virus remained inhibited in nine patients – usually for 21 weeks, although two patients spent at least 30 weeks.
Two of the 11 patients, however, were found to be HIV-resistant to at least one of the antibodies. Their viral levels increased within 12 weeks of stopping their treatment.
It's a critical point, Caskey said. People must be sensitive to the particular antibodies used in the therapy, and not everyone will be.
In a second study, the researchers administered the antibody treatment to four patients with detectable HIV in their blood. They found that the treatment had lowered these levels up to three months.
The studies were published separately on September 26 in Nature and Nature Medicine.
Dr. Melanie Thompson is President of the HIV Medicine Association. She described the new findings as "exciting", but also said that a lot of work remains to be done.
Longer-term, longer-term studies are needed to determine how often the treatment should be administered and its effectiveness over time, said Thompson, who did not participate in the new studies.
In practice, noted Thompson, the current tests used to predict the sensitivity of patients to antibodies are quite complex.
"I think the tests will have to be refined and made more affordable," she said.
As for side effects, the Caskey team said that some patients had mild fatigue, but nothing more serious.
"Until now," Thompson said, "the safety profile of these antibodies has been excellent."
Caskey raised another question for future studies: can antibody therapies over time induce the immune system to produce its own anti-HIV antibodies, reducing the need for treatment?
"New frontiers in HIV research involve looking at longer-acting treatments," Thompson said. "Can we have a long-term viral suppression with as little medicine as possible?"
Ongoing studies have been funded by the US National Institutes of Health, the Bill and Melinda Gates Foundation, and other grant programs.
More information
The US National Institute of Allergy and Infectious Diseases has more information on HIV treatment.
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