Therapeutic HIV Vaccines: Prior setbacks, current advances and future prospects

July 23, 2014

Getting into a taxi in any country and ask the driver about the AIDS epidemic is a great way to learn about local views and priorities—and to gauge what news has grabbed the popular imagination. From a decidedly unscientific survey, we’ve found that the notion of a cure for AIDS has dominated taxi discourse—and conversations in many other places—for much of the past year. One of the stories that seized attention of drivers, advocates and scientists was that of the “Mississippi baby”—an infant who was treated after birth with highly active antiretroviral therapy and was then lost to follow up. When she returned to medical care, she had no detectable virus in her blood—and it was thought that she might be cured of HIV.

Recently, there’s been disappointing news of a reversal in this case. Doctors have now detected HIV in the child’s blood for the first time in the two years that she spent without taking antiretrovirals. The fact that the child spent that much time off treatment with no detectable virus is intriguing, since it suggests that she was effectively controlling the virus via immune responses. The fact that the virus returned underscores how far we may have to travel to get to a cure. Treatment Action Group’s Richard Jefferys has an excellent blog post summarizing knowns and unknowns around these developments.

For a look beyond the headlines at the agenda, funding needs and challenges related to cure and therapeutic vaccine research, check out a recent article by AVAC, the Treatment Action Group, and the Global HIV Vaccine Enterprise. This piece builds on the discussions at a workshop on therapeutic vaccines that the groups held together in September 2013 and which included over 100 researchers, funders and advocates to discuss current issues in therapeutic HIV vaccine research and development.

Therapeutic vaccines are tools that aim to help people with HIV control the virus through enhanced HIV-specific immune responses. No such vaccine exists but in theory it could improve treatment efficacy or perhaps, some day, eliminate the need for ART.

Therapeutic vaccines have become a hot topic in cure conversations, too. It’s clear that HIV lurks in dormant, non-replicating cells and that these reservoirs need to be eliminated for an effective cure. Cure research is exploring a variety of one-two punch combinations that would flush out these reservoirs and then neutralize the remaining virus. A therapeutic vaccine could be an ideal tool for the second step in this process.

As the recent paper describes, research and investment into therapeutic vaccines has languished in the past few years. The paper suggests that there is a way to revamp and refocus the current pipeline of candidates to target immune responses not found in natural infection or targeted in previous studies. The paper notes that strategies to enhance vaccine responses in the therapeutic context should develop separately from work on preventive vaccines—but that the two fields should be in close communication to maximize synergies.

Unfortunately, when there’s a setback like the viral rebound in the Mississippi baby case, this too makes headlines and can turn “taxi talk” to despairing statements about how we won’t ever vanquish the virus. The truth is that we don’t yet know whether therapeutic vaccines can be developed to effectively control ART—and we don’t know whether a cure will be possible. But it’s important to move forward with sustained and energized research. There are clues to follow and uncertainty is unavoidable. At a moment like this one, when the headlines are reporting disappointing news, it’s especially important for advocates to help convey the necessity of moving forward.