On Tuesday, at the 10th annual International Aids Society (IAS) conference in Mexico City, researchers from the drug company Merck presented the results of a recent clinical trial, which found that an arm implant effectively delivered an anti-HIV drug for 12 weeks—with potential to deliver enough of the drug for up to a year. (The research has yet to be published in a peer-reviewed journal.)
The implant uses islatravir, a nucleoside reverse transcriptase translocation inhibitor that prevents the HIV virus from replicating in the body by blocking an enzyme that clones HIV's DNA. Roy D. Baynes, MD, Merck’s chief medical officer, told The New York Times that islatravir is 10 times as powerful as previous HIV drugs, so smaller amounts are effective; it is also absorbed into anal and genital tissues to help stop infections at the source. The matchstick-size device created to carry the drug is designed similarly to Implanon and Nexplanon, two types of birth control implants.
In the small double-blind clinical trial, a total of 16 healthy adults were assigned to receive an implant with either a 62 milligram dose of islatravir, a 54 milligram dose, or a placebo. They kept the implant in place for 12 weeks, then it was removed and they were monitored for an additional four weeks. Throughout the study, participants were monitored to check on the levels of the drug in their systems as well as to make sure they weren't experiencing any side effects or reactions. Researchers found that the implant containing 62 mg of islatravir resulted in intracellular levels of the drug at levels above the minimum threshold required to fight off HIV with minimal side effects, according to a press release from Merck—meaning that the implant could be effective at preventing HIV infection for at least 12 weeks. Additionally, researchers calculated that the implant would likely deliver enough of the drug to last for 16 months.
While the findings are very preliminary (note that tiny study size, and the fact that it just looked at safety and levels of the drug in one's system, not its actual ability to fight HIV), it's a pretty exciting new breakthrough in the world of HIV prevention. There are already very effective drugs available that prevent HIV transmission, but most (like Truvada) require people to take a dose of the medication every single day to be effective. Think of this implant as potentially the IUD of HIV prevention—if further trials pan out, a person could get an arm implant once and be protected against HIV for a long period of time.
“An implant offers another choice for those who might in the future also have pills and injectables available. It could also offer a promising solution to those who face challenges adhering to a daily PrEP regimen,” said Anton Pozniak, International AIDS Society President and IAS 2019 International Scientific Chair according to a press release from the IAS.
Don't expect the implant to be available any time soon though. It will need to go through rigorous human trials proving that it can actually prevent HIV infections (and that it's safe to use for long periods of time) before even being considered for approval by the FDA. It's also unclear right now what the cost of this kind of device would be. Dr. Baynes didn't give any specifics to The New York Times except to say that Merck was committed to "responsible pricing."
It's also important to note that like other PrEP drugs, islatravir would only protect against HIV—not other STIs. (A person with the implant would still need to use other protection methods like condoms to better avoid all STIs out there.)
Still, it's a promising breakthrough that could make a big difference in the fight against HIV. “If—and I’m emphasizing if—if it pans out in a larger trial that it delivers a level of drug that’s protective for a year, that would be a game-changer,” Anthony S. Fauci, MD, director of the National Institute for Allergy and Infectious Disease, told The New York Times. Hear, hear.
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