Anti-Heroin Vaccine Shown Effective in Rhesus Macaques

Jun 7, 2017 by News Staff / Source

An anti-heroin vaccine created by scientists from the Scripps Research Institute and Virginia Commonwealth University to block the ‘high’ of heroin, a highly abused opioid, has proven effective in rhesus macaques. This is the first vaccine against an opioid to pass this stage of preclinical testing.

The anti-heroin vaccine candidate is effective in mice and rhesus monkeys. Image credit: Bremer et al, doi: 10.1021/jacs.7b03334.

               The anti-heroin vaccine candidate, described in the Journal of the American Chemical Society, was developed by a team led by Kim Janda, the Ely R. Callaway Jr. Professor of Chemistry and member of the Skaggs Institute for Chemical Biology at the Scripps Research Institute.
The vaccine works by exposing the immune system to a part of the heroin molecule’s telltale structure. This teaches the immune system to produce antibodies against heroin and its psychoactive products. The antibodies neutralize heroin molecules, blocking them from reaching the brain to cause a feeling of euphoria.
Prof. Janda and co-authors believe that blocking the high of heroin will help eliminate the motivation for many recovering addicts to relapse into drug use.
The researchers have been working on their heroin vaccine for over eight years; they had previously tested vaccine candidates under laboratory conditions and in rodents, where the strategy proved effective for neutralizing heroin.
              For the new study, in rhesus macaques, the authors redesigned their vaccine candidate to more closely resemble heroin, with the goal of better stimulating the immune system to attack this opioid.
They found that the four primates that were given three doses of this vaccine showed an effective immune response and could neutralize varying doses of heroin.
This effect was most acute in the first month after vaccination but lasted for over eight months.
The scientists also found no negative side effects from the vaccine.
“This validates our previous rodent data and positions our vaccine in a favorable light for anticipated clinical evaluation,” Prof. Janda said.
“We believe this vaccine candidate will prove safe for human trials.”
            “The components of the vaccine have either already been approved by the FDA or have passed safety tests in previous clinical trials.”
Interestingly, two of the four primates tested had been pre-vaccinated with the same vaccine candidate for a more basic pilot study seven months prior to the experiment in this study.
The researchers found that these two primates showed a much higher response to the vaccine in the second round of experiments.
This suggested their antibody-producing cells held an immunological ‘memory’ of the vaccine. If this effect holds true in humans, a recovering addict would have long-term immunity to heroin.
“We were really encouraged to see the vaccine produce such lasting effects in non-human primate models,” said first author Paul Bremer, also from the Scripps Research Institute.
The scientists noted that this vaccine candidate works only against heroin and not other opioid-based pain killers or medications for treating opioid addiction or overdose, leaving those open for use in emergency medical situations and for prescription medicines and substance use disorders.
The next step for the team will be to license the vaccine to an outside company for partnering in clinical trials.