HIV-Preventing Arm Implant Shows Promise In First Human Trial

A tiny implant that prevents HIV infection for as long as a year has shown promise in its first-ever human trial. The implant could one day provide a favorable alternative to pills taken every day.



Pre-exposure prophylaxis, aka PrEP, is a drug taken daily by those who are HIV-negative but might come into contact with the virus through sex or drug use. In the US, PrEP is approved by the FDA and sold under the brand name Truvada. In the UK, PrEP can be obtained through the National Health Service (NHS) as part of their PrEPARED trial. You can keep an eye on PrEP access in other nations via PrEPWatch.

While the drug is highly effective when taken correctly, it can be difficult to remember to take the pill on a daily basis, an issue many women face with the contraceptive pill. That’s where the new implant comes in. The size of a matchstick, it is inserted into the arm and slowly releases PrEP drugs over a long period of time.

The results of the new trial were presented at the 10th International AIDS Society conference in Mexico City. The trial included just a small number of participants, but the results are nevertheless promising.

A total of 12 healthy adults used the implant for three months while four control subjects received placebo implants. The majority of the participants – 14 out of 16 – were men. The results of the trial showed that the implant was both long-acting and well tolerated.

The implants contained a different drug to those currently available as pills. Known as islatravir, the drug contains a molecule called MK-8591, which is about 10 times more effective at preventing HIV than the PrEP drugs we currently use.

Back in July, the United Nations reported that deaths from AIDS – the set of life-threatening infections and illnesses that occur as a result of HIV – had dropped by a third since 2010. While this is exciting, the UN was quick to warn that AIDS deaths are not decreasing everywhere. Africa, which was heavily affected by the 1990s AIDS epidemic, has seen a reduction, however, deaths in Eastern Europe have risen by 5 percent, while deaths in the Middle East and North Africa have increased by 9 percent.

Curbing new infections is an important step in the fight against AIDS, so preventative measures like PrEP are key. At the moment, PrEP can reduce infection risk by 90 percent in those exposed to HIV through sex and 70 percent for those exposed through drug use.

"The people that are at highest risk are different populations – for example, men who have sex with men still remain in the US and Europe the group that has the highest rate of new infections," Mike Robertson, director of global clinical development for virology at MSD research, told AFP.

"But globally the highest incidence rate is in young women in sub-Saharan Africa and this is another group where most the new infections are occurring."

In sub-Saharan Africa, implants are often seen as more acceptable than taking pills, with the method being increasingly used for contraception. Introducing an anti-HIV implant to this region could make a real difference.

"Ending AIDS is possible if we focus on people not diseases... and take a human rights-based approach to reaching people most affected by HIV," Gunilla Carlsson, UNAIDS executive director, said back in July.

The implant still has a long way to go in terms of clinical trials and testing, but it could one day revolutionize HIV prevention. Meanwhile, a recent Phase 2 clinical trial of a new HIV vaccine has had successful results, and a Phase 3 trial is scheduled. New solutions like these could help us suppress the spread of HIV in the coming decades.

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