HIV Vaccine Trial Called Off Due To Lack Of Success

HIV vaccine trial HVTN 505 was suddenly called off three years into testing after an independent data and safety monitoring board found that the vaccine was not working.

Not only was the vaccine under investigation not preventing HIV infection, said a statement issued by the National Institute of Health (NIH) who oversaw the trial, but even the viral load, or amount of HIV in the blood, went unaffected.

Funded by HIV Vaccine Trials Network, the investigational vaccine included a series of three immunizations over the course of eight weeks, the first of which contained genetic material expressing antigens that represented proteins found both in the surface and internal structures of HIV.

This “priming” vaccine was then followed by a booster vaccine 24 weeks later based on a weakened adenovirus used to carry genetic material expressing a matching set of HIV antigens, including all three major subtypes of the virus.

Neither injection had any possibility of causing HIV infection as neither contained live or weakened versions of the virus, according to the NIH.

In all, 2,504 volunteers from 21 sites in 19 U.S. cities were enrolled in the study and consisted exclusively of men who have sex with men and transgender people who have sex with men.

In the April 22 interim review, the Data and Safety Monitoring Board (DSMB) examined information taken from 1,250 volunteers who received the investigational vaccine regime and 1,244 who receive the placebo.

The primary analysis looked at volunteers diagnosed with HIV after having been in the study a minimum of 28 weeks.

In all, the board found that 14 cases of HIV infection occurred during the given time frame among those who had received the investigational vaccine while only 9 occurred among those who received the placebo.

In terms of viral load, the DSMB found that both groups – those who had received the potential vaccine and those who received the placebo – were split equally with 15 from each group of participants showing a measurable viral load 20 weeks after diagnosis.