Trial of University of Minnesota's opioid vaccine underway

Clinical trials are underway to test the safety and effectiveness of an experimental vaccine developed at the University of Minnesota Medical School against opioid-use disorders.

U researchers hope the first-of-its-kind vaccine will counter the rapid growth in U.S. overdose deaths — which accelerated during the pandemic — but said recruitment for the intensive trial in New York has been a challenge since it launched last fall.

"In 2020, after COVID started, the statistics were horrible," said Marco Pravetoni, a U associate professor of pharmacology who developed the experimental vaccine. "We went up to 92,000 drug-related deaths, of which 69,000 were opioids. So almost double [pre-pandemic totals]. In some states, the overdose rate doubled or tripled. It's just crazy. We've been working on this for a while and we really want to accelerate how we move this stuff forward."

The injection is designed to work like common vaccines, stimulating an immune response to opioid molecules that would prevent the euphoric effects and resulting overdose. The initial trial (known as a phase 1 trial in the run-up toward approval by the U.S. Food and Drug Administration) is seeking 45 participants to prove that the vaccine can be safely tolerated and to provide initial evidence of an effective immune response.

The trial's requirements make recruitment challenging, because it needs people who are using opioids but not receiving treatment for drug abuse. Volunteers also must agree to spend weeks in inpatient hospital care while they are monitored for side effects and take oxycodone to see if the vaccine inhibits its effects.

The trial is taking place at Columbia University Irving Medical Center in New York, partly because it has the psychiatric facilities to carry out the initial inpatient phase of the trial, Pravetoni said.

The first vaccine candidate is designed to block the effects of oxycodone, a common opioid prescription painkiller. While the vaccine would consequently prevent the use of oxycodone for pain management, doctors could prescribe other drugs.

Pravetoni and colleagues started the research in 2008, and targeted oxycodone because it was one of the leading causes of opioid overdose deaths at the time. Since then, fentanyl and more potent synthetics have become the dominant causes of opioid deaths.

Development of a vaccine targeted to fentanyl is underway, Pravetoni said, and the ultimate goal is a universal vaccine that targets multiple opioids at once.

The Minnesota Department of Health in May reported a 59% increase in opioid-involved deaths — from 412 in 2019 to 654 in 2020. More than 80% involved fentanyl, the opioid that caused the 2016 death of pop star Prince. Opioid deaths leveled off or declined from 2017 to 2019 in Minnesota — amid a series of state efforts to reduce excessive prescribing — before rising again during the pandemic.

Pravetoni said the rapid adoption of the COVID-19 vaccines has served as an inspiration to accelerate the development of opioid-use vaccines, which would probably need to be provided in initial doses and then regular boosters over time. The platform by which the experimental oxycodone vaccine was developed at the U will hasten the creation of vaccines against other opioids, he added.