Life expectancy in the United States declined for the second year in a row due to an opioid epidemic, but a new vaccine shows promising results in mice and rats.
F or the first time in a half a century, life expectancy in the United States declined for the second year in a row — and America’s opioid epidemic is to blame. A child born in 2016 is expected to live 78.6 years, down from 78.7 years in 2015 and 78.9 in 2014, according to statistics released by the US Centers for Disease Control and Prevention.
“Two years in a row is quite shocking,” Robert Anderson, chief of the mortality statistics branch at the National Center for Health Statistics, told AFP. “The key factor in all this is the increase in drug overdose deaths.”
Yet amid the overdose epidemic, another opioid vaccine has shown promising — albeit early — results in the laboratory.
Scientists at the US Military HIV Research Program at the Walter Reed Army Institute of Research (WRAIR) recently developed a vaccine that blocks the opioids in heroin from reaching the brain in mice and rats, offering a potential breakthrough in treating opioid addiction.
When injected, the heroine vaccine releases antibodies into the blood that prohibit the drug from breaking through the blood-brain barrier. This means that even if a heroin addict shoots up, they won’t experience a high. The vaccine includes a potent adjuvant, a substance that boosts the body’s immune response to a toxin, called the Army Liposome Formulation, also developed by researchers at WRAIR.
“All vaccines to substances of abuse function through causing the body to make antibodies that bind the drug of interest and prevent it from entering the brain,” Dr. Gary Matyas, chief of adjuvants and formulations for the US Military Research Program and one of the study authors, told Seeker.
While Matyas and his team have not directly tested their vaccine against vaccines from other research facilities, they have tested it against an older vaccine developed by WRAIR and found that the new one is more effective and very stable. “[Its stability] should increase its shelf-life and keep it from degrading during vaccine manufacturing and storage,” Matyas said.
Their study, published in the Journal of Medicinal Chemistry, found that this new vaccine was not only effective in preventing heroin from reaching the brain but worked with other commonly abused opioids as well, including hydrocodone, oxycodone, hydromorphone, oxymorphone, and codeine. It also lowered the toxic effect of very high doses of heroin, which could be key in preventing overdoses.
The antibodies in the vaccine did not bind to several other opioids like methadone, tramadol, sufentanil, nalbuphine, buprenorphine, and fentanyl. Fentanyl is one of the most widely abused synthetic forms of heroin and 100 times more powerful, which makes it extremely deadly. Due to the high risk of overdose, some researchers have prioritized the development of a treatment method specifically for fentanyl abuse. Along with their heroin vaccine, the Scripps Institute tested a fentanyl vaccine in mice and found it to be similarly effective, but clinical trials are still needed.
The discovery that the WRAIR vaccine does not interfere with opioids like methadone and buprenorphine turned out to be a positive development, as these drugs are often used in current treatment methods for opioid addiction. Because the vaccine’s antibodies do not bind with methadone, buprenorphine, or naltrexone, it can potentially be used in combination with these therapies.
Most importantly, the vaccine did not react with naloxone, which is used in emergency overdose rescue treatments to reverse respiratory complications. And it did not react to non-opioid pain relievers like ibuprofen or aspirin.
While this research is an important advancement in treating opioid addiction, it could be several years before the vaccine is commercially available. “Vaccines typically take many years to develop, test, and manufacture, and we are still in the early stages,” Matyas said. “We are currently pursuing funding for a clinical trial [and] we have licensed the product to Opiant Pharmaceuticals to continue development and manufacture at the appropriate point.”
Administering methadone or buprenorphine is the most common treatment option for heroin addicts, but these methods are often expensive and require inconvenient daily trips to a clinic. What’s more, the chance of relapse afterwards is very high. 91 people die every day from an opioid overdose in the US, according to the CDC. By addressing the issue of relapse due to intense cravings, this new vaccine offers one additional solution for treatment.
The US military’s vaccine, funded by the National Institute of Health, the Henry M. Jackson Foundation for the Advancement of Military Medicine, and the US Army, is not the only one in development. In June, the Scripps Research Institute published their work on a similar vaccine that was found to be effective in mice, as well as rhesus monkeys, and other opioid vaccines are also being developed and tested in order to address the growing epidemic.
A combination of methods will be necessary to end one of the worst drug epidemics in modern American history, which is why Matyas considers his preclinical data very promising.
“It’s unlikely that any one therapy or strategy will end the opioid crisis, but we hope that a vaccine will be a new tool in the toolbox,” Matyas said. “Many different types of treatments and medications will be necessary to meet the diverse needs of individuals addicted to opioids.”