Could an implant protect against HIV for up to a year?


Hopes are high for a new implant that could provide year-long protection against HIV for people who do not have the virus. 

The device, a new venture by Merck, has proven a success in rodents and monkeys, and safe for at least three months in 12 human volunteers. 

But researchers at the pharmaceutical company – and, tentatively, other experts in the field – say the latest research, presented today, is strong enough to call this a potential ‘game changer’. 

If successful, the device, containing Merck’s new HIV-abating drug islatravir, would be the equivalent of switching from the birth control pill to the long-lasting implant to prevent pregnancy: people who do not have HIV could ditch the daily pill that lowers their risk of infection, and instead get their implant replaced annually. 

However, there is still no word on whether it would be affordable for those most in-need, and Merck’s research has yet to prove that it works in humans, beyond safety trials, and that its effects do really last a year. 

‘If in fact this pans out – and I’m saying if – this could truly be game-changing,’ Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases who has long been on the front lines of HIV research, told 

There have been other efforts to provide long-term protection from contracting HIV, such as an injection. But nothing with the potential to last a year long, with (again, potentially) so few side effects. 

A decade ago, scientists discovered a drug, taken daily, could lower a person’s risk of contracting HIV by 99 percent – more effective than many birth controls at preventing pregnancy. 

That medication is known as PrEP (pre-exposure prophylaxis), and was hailed as the answer to preventing further spread of HIV. 

Its potential was not fully realized. 

That was partly to do with price – Gilead, which holds the patent on the brand-name version Truvada, priced it at $20,000, and though some have sought access through government or philanthropic programs, that is not so easy for others, particularly in the Bible Belt of the US and in rural parts of Africa. 

Another significant factor was lack of adherence. As is the case with all daily medications, especially those taken by people who are not sick, studies have shown a tendency for people to drop off, or at least take it irregularly.

Merck’s research, presented at the International AIDS Society conference in Mexico City today, has the potential to resolve the latter – though they are tight-lipped about the former. 

‘I’ll tell you why this is the trial I’m cautiously optimistic about,’ Dr Fauci said. 

‘There was another study reported in Mexico City that, when you juxtapose it with this one, shows its potential.’

The study he refers to was conducted in Sub-Saharan Africa, inviting dozens of people to try PrEP for free to protect them from contracting HIV. 

After three months, 85 percent were still taking it, based on levels of the drug in their blood. 

But by the twelfth month, only nine percent were taking it. 

‘Even when you enforce in a very high intensive way treatment as prevention, it does not significantly decrease the rate of infection,’ Dr Fauci said. 

‘Ask anyone: having to do something over and over again, having to take a pill every single day – people don’t want to be continually reminded every single day that they have to take a drug.’ (The injectable, he adds, is something, but ‘you have to give that every couple of months’.)

‘If we could have a tool to protect people for up to a year… yes, that would be a game changer.’

The drug itself is one of many new drugs called NRTTIs (nucleoside reverse transcriptase translocation inhibitors), which suppress enzymes that allow HIV to multiply. 

And it is incredibly potent. Just a fifth of the drug, islatravir (or, MK-8591), is enough to achieve the same effects as PrEP, Merck’s research suggests. That could mean fewer side effects.   

Human trials, not yet described publicly, will have to confirm whether the implant, which can hold up to a year’s supply of the drug, will indeed be effective for an entire 12 months. 

‘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,’ Anton Pozniak, International AIDS Society President and IAS 2019 International Scientific Chair, said in a statement. 

‘Taken together, the HIV prevention studies presented at IAS 2019 show that we are creating new tools to address the realities of people’s lives.’


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