Opioid-related drug overdose deaths in the United States exploded to an estimated record high of 69,031 people in 2020, topping the 49,860 deaths logged in 2019, according to a new report from the Centers for Disease Control and Prevention. Most of the deaths involved synthetic opioids such as fentanyl.
President Joe Biden has pledged more than $10 billion to expand access to prevention, treatment, and recovery services. The money is important as people receiving treatment for opioid use disorder have a high risk for relapse, and that means a high risk for opioid overdose.
Now, researchers are studying a possible bridge to successful recovery: A vaccine that could blunt the drugs’ ability to cause harm.
The first such vaccines are now entering clinical trials, raising hopes of adding another tool to the antiaddiction armamentarium. But even if the vaccines prove safe and effective, their success could generate some new problems to solve.
An advantage of vaccines is that their effects can last for several months, said trial investigator Sandra Comer, PhD, professor of neurobiology and psychiatry at Columbia University Irving Medical Center, New York. Dropout rates for existing medical therapies for opioid use disorder are as high as 50% at 6 months, and a vaccine could protect people from overdose and give them time to re-enter treatment.
“It serves as a bit of a safety net,” she said.
The first vaccine to enter a trial targets oxycodone. Volunteers are being recruited who have a diagnosis of opioid use disorder but are not being medically treated and are still using opioids. A third of them will receive a placebo vaccine, a third will receive a low-dose injection of vaccine, and the other third will receive a high-dose vaccine.
A shot against oxycodone
Researchers are primarily tracking the safety of the shot, but they’re also looking at whether vaccination prevents the euphoria that opioids usually produce. They expect to enroll 24 people initially but expand to 45 if results look promising.
In response to the shot, the body produces antibodies, proteins that tag oxycodone and keep it from reaching the brain. If the drug can’t reach brain cells, it can’t produce euphoria. And more important for lifesaving effects, it can’t block the brain’s signals to the body to breathe. The vaccine has already performed well in animal studies.
Previous trials of vaccines for cocaine and nicotine failed. Those vaccines made it to the last clinical trial stage, but didn’t prove effective overall. So this time, investigators plan to track antibody levels in participants, examining blood samples for signs of a good immune response to the vaccine.
But even though earlier cocaine and nicotine vaccines didn’t work for everybody, there were some people they seemed to help. This is why investigators involved in opioid vaccine trials want to track immune responses, said Marco Pravetoni, PhD, associate professor of pharmacology and medicine at the University of Minnesota, Minneapolis, whose team will be assessing the blood samples. Ultimately, a doctor might even be able to use this information to tailor vaccine selection to a specific person.
Dr. Pravetoni also said that oxycodone is one of three vaccine targets – the other two are heroin and fentanyl – that researchers hope to combine into a single shot. Recipients might need to have one shot a month for the first 3 to 4 months and then receive annual boosters.