Researchers have found a new antibody that could suppress the levels of HIV for upto four months in the absence of antiretroviral therapy in HIV patients. The study has been published in The New England Journal of Medicine.
Patients infected with HIV are currently treated with a combination of antiretroviral drugs designed to prevent the replication of the virus within the body and delay the onset of AIDS. Although the treatment regimens are able to keep the virus under control, missing the doses could increase chances of HIV becoming resistant to the drugs.
With the advances in antibody technologies, researchers have been working on developing potent and broadly neutralizing antibodies against HIV. Such antibodies are being investigated as a potential means to prevent viral rebound after discontinuation of antiretroviral therapy to allow patients to take a break from taking so many pills without harmful effects on their health.
A novel antibody known as UB-421 has been tested in patients with HIV who had been undergoing antiretroviral treatment for over 5 years. The patients were put on a short-term break in their antiretroviral regimen during the clinical trial.
The trial involved 29 participants who were separated into two cohorts of 14 and 15 participants respectively. During the screening visit all participants showed an undetectable plasma viral load (<20 copies of HIV RNA per milliliter). After discontinuation of antiretroviral therapy, participants received eight intravenous infusions of UB-421. The antibody was given at a dose of 10 mg per kilogram of body weight every week for Cohort 1 and 25 mg per kilogram every 2 weeks for Cohort 2. The time taken for viral rebound was observed.
HIV levels were maintained below the limit of detection in all patients for up to 16 weeks. UB-421 was therefore proven to effectively control HIV from replicating further and spreading infection. Furthermore, no evidence of HIV resistance to UB-421 was observed. However, due to the small size of the study, future clinical studies with long-term monitoring for drug-resistant HIV strains are needed.
“We were able to use this antibody to maintain durable viral remission using a single agent instead of a cocktail of drugs. Such durable maintenance is unprecedented, and it opens up a host of potential new treatment options for patients with resistance-prone HIV infection.” said the lead author Chang-Yi Wang in a press release.
UB-421 acts to prevent HIV infecting immune cells by blocking the binding site. It binds to immune cells with 50 to 100 times greater affinity than HIV, and so binds in preference to the virus.
Ex-vivo studies have shown UB-421 to have a significantly greater viral inhibition capability than other previously tested HIV-neutralising antibodies.
A clinical study is now being developed to test UB-421 in people with HIV infection who have not yet started anti-retroviral therapy to see if the antibody can suppress HIV activity for more than 25 weeks.