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Scientists are getting ready to kick off the first human trials for a pair of vaccines designed to block the effects of fentanyl and heroin.

The hope is to stop people from accidentally consuming a lethal dose, a grim outcome that has become a significant risk, particularly in the US. In 2021 alone, tens of thousands of people in the country died as a result of an opioid overdose, according to the National Institute on Drug Abuse. And opioid-related deaths have been on the rise since at least 1999, figures show.

But a simple injection that could allow the body to neutralize fentanyl and heroin in the body could help turn things around — or, at least, that's the hope.

"In principle, as a vaccine, it's pretty simple," Jay Evans, director of the University of Montana Center for Translational Medicine, and co-founder of Inimmune, the corporate partner tasked with scaling up production of the vaccine, told Futurism. "You can generate an antibody response against the drug. If that antibody binds to the drug in the bloodstream, it prevents it from crossing the blood-brain barrier."

In simple terms, the vaccine effectively eliminates the drug's "high," since it isn't able to spread to the brain. In theory, that could be a powerful weapon against addiction.

The antibody bonds to the fentanyl "kind of like a sponge," Marco Pravetoni, a professor of psychiatry and behavioral sciences at the University of Washington who's also involved in the research, explained in a separate interview. "And that fentanyl is no longer available to get to your brain to activate opiate receptors. So it's essentially removed from the circulation."

The idea is to block the effects of opioids while still allowing other opioid-specific treatments — think Narcan, the brand name of naloxone, which can reverse a potentially fatal overdose through a nasal spray — to still be effective.

Another wrinkle: the vaccine could prevent fentanyl from being used as a legitimate medicine, such as in anesthesiology.

"I've had a number of physicians, especially anesthesiologists who have sent me an email and say, 'What are we going to treat patients with in the operating room who've had this vaccine?'" Evans said.

Fortunately, there are plenty of other drugs healthcare providers could still fall back on once a patient is administered the vaccine.

"The vaccine is very specific for fentanyl and fentanyl analogues," Pravetoni told Futurism, "so you could still use anesthetics. So you can still do your surgery."

Preclinical studies involving animal models have also shown that the vaccines spare "critical medications such as methadone, buprenorphine, naltrexone and naloxone, which are used in treatment of opioid addiction and reversal of overdose," as Pravetoni explained in a statement about the research.

The ongoing opioid crisis has been decades in the making. Fentanyl was first introduced in the 1960s as an intravenous anesthetic. It's around 100 times more potent than morphine and 50 times stronger than heroin when it comes to pain relief.

Its recreational effects have made it a particularly popular street drug. It's notoriously easy to overdose on the drug outside of a hospital setting, especially when it comes to synthetic fentanyl illegally sold as powder or mixed in with other drugs. A few grains can be enough to prove fatal.

The concept of opioid vaccines has been "around for a long time," Pravetoni told Futurism. 1970s literature showed that "essentially, you could vaccinate a non-human primate and stop it from self-administering heroin," a line of research that was soon abandoned.

As more opioids entered the scene and became available to the public, "the concept of immunotherapy for opioids, for either addiction or overdose, was sort of in standby," he added. "So there was a lag in research."

In the 1990s and early 2000s, researchers including Pravetoni started investigating vaccines targeting nicotine and cocaine.

While some of these vaccines reached Phase 3 clinical trials, none of them "really reached the market," Pravetoni explained.

Fast forward several decades, and the enthusiasm behind developing opioid vaccines has increased again, with Evans, Pravetoni, and their colleagues picking up where they left off, applying what they learned from their previous efforts.

That's in large part thanks to the National Institutes of Health's (NIH) Helping to End Addiction Long-term Initiative (HEAL), which has made tens of millions of federal dollars available for Marcetoni and Evans to investigate these vaccines.

In fact, Evans says his research is 100 percent funded by the NIH.

While it's still far too early to determine the effectiveness of these vaccines in humans, there are early reasons to be optimistic.

Preclinical trials, as laid out in a pair of papers published in the journal NPJ Vaccines earlier this year, showed that the vaccine was able to stop fentanyl from reaching the brain in rats and pigs.

Following vaccination, doses of fentanyl had "no effects" on these animals "because it doesn't reach the receptor," Evans explained. "And then it just gets recycled out of the body."

More specifically, the implication is that "the vaccine will prevent respiratory depression or bradycardia that are associated with overdose and fatal overdoses, but also prevent the euphoric effects or the high," Pravetoni told us.

That could make it a great solution for those "who are addicted to fentanyl or heroin and go into a rehab center and they want to quit and it's really hard to quit," Evans said.

Unfortunately, there's always a chance that somebody could try to chase the high after being vaccinated against fentanyl and turn to use other drugs, something "the vaccine is not going to prevent," Evans explained.

Then there's the stigma surrounding addiction.

"You're not afraid to tell someone if you have influenza, if you have COVID, but you're afraid to tell someone if you're addicted to opioids" because of "this negative stigma about it," Evans said.

Pravetoni hopes a vaccine could provide "broader acceptance" and "open up more avenues" for people, who are "not interested" in taking opioids due to existing stigmas.

Now, Evans, Pravetoni, and their colleagues are starting the process of clinical trials designed to test the safety of these vaccines, the first step in what will likely be a lengthy, years-long process.

Phase 1 trials, which will take place at Columbia University in New York City and are expected to start in early 2024, will see participants who are already using these drugs take increasing doses of the vaccines to ensure it's safe.

If these early clinical trials prove successful, phase 2 trials could then determine how many doses would be needed, and at what intervals, to be effective. Finally, phase 3 trials would allow the US Food and Drug Administration to evaluate if any potential risks are outweighed by the benefits of the vaccines by enrolling a much bigger number of participants.

"It takes a long time — years — to get to a final approved product," said Evans in the statement. "Based on the efficacy data we see in our preclinical data and the established safety profile in animal models, we are very hopeful these vaccines will be successful."

"But there is still a lot of work to be done," he added.

In a perfect world, Evans said that he hopes to have the effects of the vaccine last only a number of years.

"Patients who are addicted to opioids and want to quit and going through rehab, their chance of relapse in the first two years is 80 to 90 percent," he said. "If they can get past those two years, their chance of staying clean is very good. So our goal is to protect people during those two years, when their highest risk of reusing an overdose."

"And so we want the we want the antibody titers to stay really high for a couple of years, and then actually wane off over time," Evans explained. " So if that patient ten years down the road, was going in for surgery or in an accident, and needed to use fentanyl as a pain relief medicine, then that would be then available to that person again."

At the end of the day, vaccines, if they ever make it to market, will only be one small part of a much broader picture.

"Essentially, you need all the help, you can get, so hopefully, vaccines and antibodies can provide that extra layer of protection," Pravetoni told us.

Then there's our current healthcare system's reliance on opioids.

"Ultimately, I would love to see non-opioid-based pain medicines that are just as effective as the opioid-based ones," Evans said, "and have all of the opiate-based pain medicines become basically illegal drugs. And so people who are becoming addicted aren't because they're dealing with chronic pain."

It's part of a much larger and immensely complex picture, and plenty of factors have to be taken into consideration, from "how doctors prescribe opioids, and how they educate patients on how to take those opioids to prevent addiction" to "reducing the stigma about addiction," according to Evans.

"As long as that stigma is in place, it's going to be hard to get to treat the patients that really need it," he added, arguing that public education is a "big part of it."

"You need a toolbox of tools to help this crisis," Evans said. "The vaccine alone isn't going to solve it."

More on fentanyl vaccines: New Vaccine Blocks Fentanyl in Brains of Rats

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