Researcher reveals decision-making criteria for possible AIDS vaccine efficacy trials in 2017

May 18, 2015

The AIDS vaccine field has been energized by the recent launch of early clinical trials in South Africa – trials that could eventually lead to the first vaccine licensed for use. The vaccine being tested is a modified and hopefully improved version of the first and only AIDS vaccine candidate thus far to show moderate efficacy in preventing HIV infection in the RV144 trial in Thailand that finished in 2009.

This vaccine candidate will only move to large-scale efficacy trials – which are the prerequisite for licensure – if researchers decide it has a good chance for success. How will they know, and when will they know it?

The answers were outlined for advocates by the HVTN’s Glenda Gray on the AVAC webinar to mark HIV Vaccine Awareness Day (HVAD) 2015.

Gray discussed an ongoing trial of the ALVAC-protein vaccine candidate, HVTN100, which started in January 2015 in South Africa. By June 2016, there should be 12 months of data available about what kind of response the vaccine triggered among the 210 participants who received the experimental vaccine.

The specific requirements are quite technical, but basically the researchers will look at 12-month immune responses in HVTN100 and gauge the likelihood that the vaccine would maintain at least 50% efficacy for two years in the future efficacy trial. The Thai trial showed 31% efficacy overall. So if all goes according to plan in terms of timing and reaching a “go” decision, a vaccine efficacy trial with this ALVAC-protein prime-boost could start in early 2017.

On the webinar Gray also provided an update on the other planned HVTN clinical trials as part of the P5 partnership, as well as a new collaboration with the HIV Prevention Trials Network (HPTN) to advance one of the broadly neutralizing antibodies (bNAbs) into a possible efficacy trial as passive antibody prevention.

Also on the call Frank Tomaka of Janssen Pharmaceuticals, part Johnson & Johnson, presented their plans for clinical trials of his company’s new mosaic AIDS vaccine candidate using adenovirus type 26 as the vector. The suite of current trials that would lead to a possible efficacy trial in 2017 represent a significant investment by the company and welcome return of pharmaceutical industry financial investment in AIDS vaccine product development.

Finally, Bill Snow of the Global HIV Vaccine Enterprise reflected on the exciting progress in the field: after frustrating delays, we are now seeing clinical trials evaluating a trio of different approaches – ALVAC pox-protein, Ad26 mosaic, and bNAbs – that could move into efficacy trials in the coming 18-24 months. See AVAC’s new infographic for a visual display of this energized field.

An audio recording of the webinar and the presenters’ slides can be found here.