Enrollment has begun in the first of two multinational clinical trials of an intravenously delivered investigational antibody for preventing human immunodeficiency virus (HIV) infection. Known as the Antibody-Mediated Prevention (AMP) studies, the trials will test whether giving people an investigational anti-HIV antibody called VRC01 as an intravenous infusion every eight weeks is safe, tolerable, and effective at preventing HIV infection. With a projected enrollment of 4,200 adults, the studies also are designed to answer fundamental scientific questions in the fields of HIV prevention and vaccine research.
The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, is sponsoring and funding the studies.
The NIAID Vaccine Research Center (VRC) discovered the VRC01 antibody in the blood of an HIV-infected person in 2010 and subsequently manufactured the antibody for the current trials. Laboratory studies have shown that VRC01 prevents up to 90% of HIV strains worldwide from infecting human cells, and VRC01 is therefore considered to be a broadly neutralizing antibody.
The AMP studies are also expected to clarify what level of broadly neutralizing antibodies a vaccine or other long-acting HIV prevention method must achieve and maintain in order to provide sustained protection from the virus.
The first AMP trial will take place at 24 sites in the United States, Brazil, and Peru, and will enroll 2,700 men and transgender people who have sex with men. The second study is planned to launch later this spring, enrolling 1,500 sexually active women at sites in Botswana, Kenya, Malawi, Mozambique, South Africa, Tanzania, and Zimbabwe. The volunteers in both studies will be adults at high risk for HIV infection, but HIV-negative when they enter the study.
In each trial, the subjects will be randomly assigned to receive an intravenous infusion of VRC01 30 mg/kg, VRC01 10 mg/kg, or placebo (a saline solution). Neither the volunteers nor the study investigators will know who receives which type of infusion until the end of the study. Volunteers will receive a total of 10 infusions, once every eight weeks, and will then be followed for 20 more weeks.
The volunteers will be tested for HIV infection once every four weeks and at any time after reporting possible exposure to the virus. Those who test positive for HIV will stop receiving infusions of VRC01, but they will remain in the study for follow-up and will be referred to professionals in their communities for appropriate medical care.
All subjects will receive the standard care for preventing HIV infection, including condoms and lubricants, counseling on how to reduce behaviors that increase risk for infection, and counseling and referral for antiretroviral drugs to take immediately after suspected exposure to HIV (post-exposure prophylaxis). In addition, subjects in the AMP studies will be referred to local programs, where they may obtain the oral medication Truvada (emtricitabine–tenofovir disoproxil fumarate, Gilead Sciences) to take daily for HIV prevention, a practice called pre-exposure prophylaxis (PrEP). Volunteers’ access to PrEP will expand as more host countries approve Truvada for PrEP and develop the infrastructure to support its use. The AMP studies have been designed so that investigators will be able to detect a preventive effect from VRC01 even if some participants are taking PrEP.
Results from both clinical trials are expected in 2022.
Source: NIAID; April 7, 2016.