In a major blow to the effort to curtail the global HIV pandemic, a large late-stage trial of an experimental vaccine to prevent the virus has discontinued vaccinations after an interim independent review found the vaccine demonstrated no efficacy.

The Phase IIb/III HVTN 702 trial, also called Uhambo, launched in 2016 in South Africa, which has been particularly hard hit by HIV. The trial enrolled 5,407 HIV-negative men and women who were randomized to receive a series of six injections over 18 months of either the investigational vaccine regimen or a placebo.

“An HIV vaccine is essential to end the global pandemic, and we hoped this vaccine candidate would work. Regrettably, it does not,” Anthony S. Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), which is sponsoring the trial, said in a press release. “Research continues on other approaches to a safe and effective HIV vaccine, which I still believe can be achieved.”

Anthony Fauci, head of NIAID, at CROI 2019

Anthony Fauci, head of NIAID, at CROI 2019Benjamin Ryan

Two other major trials are investigating different HIV vaccine regimens. The Phase IIb HVTN 705/HPX2008, or Imbokodo, trial, includes 2,600 HIV-negative women in South Africa. The Phase III HVTN 706 or HPX3002, called Mosaico, began its launch in the fall of 2019, with a planned roll-out across the Americas and Western Europe among cisgender men who have sex with men (MSM) and transgender women.

 

On January 23, the Uhambo’s independent data safety monitoring board reviewed interim data from the trial and found that 129 participants in the vaccine arm had contracted HIV, compared with 123 people in the placebo arm. Consequently, the board concluded that the vaccine had demonstrated no efficacy—statistically, the HIV acquisition rate between the two arms was comparable—and recommended that the trial cease giving vaccination shots.

 

The NIAID agreed with this assessment and informed the participants that no further vaccinations would be given. They will continue to monitor the participants, however.

To read a press release about the vaccine trial, click here.