I’m finally over the jetlag and have caught up (mostly) with clinical duties, so here is my brief summary of the key messages from the Boston HIV conference I attended. There’s a lot to cover, so I will focus on the most important and interesting areas.
New Drugs for HIV Treatment
The new single tablet regimen that has been licensed in the US, bictegravir/emtricitabine(FTC)/tenofovir alafenamide(TAF), is looking like a great option. It’s called Biktarvy there. (Who gets paid to come up with these names, right?) Biktarvy is proving to be just as effective at maintaining viral suppression as the other current single tablet options, and it has no booster and virtually no drug interactions. Bictegravir also seems to have a very high barrier to resistance and can be used in people who already have resistant virus. The TAF component of the pill also suppresses Hepatitis B, so it will be a suitable option for people who are co-infected. It is expected to be listed in Australia in the future.
There’s a new kid on the block–MK8591 (also called EFdA). It really does need a snappier name, but I think we will be hearing more about this one in the future. It’s in a new class of antiretrovirals, the nucleoside reverse transcriptase translocation inhibitors (NRTTI), has a very long half-life and is highly potent. It’s being studied for its suitability as both a treatment and as PrEP, possibly as either a weekly pill or as an implant.
Another completely new drug is Ibalizumab. It’s a monoclonal antibody, given as an intravenous infusion every 2 weeks. It’s active against multi-resistant HIV, and has been approved in the US for people with very limited treatment options due to resistance. It’s the first new drug option we’ve had for salvage therapy in quite a while.
Broadly neutralizing antibodies (BNAbs) are another form of immunotherapy that have promising potential for use in both prevention and treatment, but are likely to be quite expensive to manufacture, and their long-term safety and efficacy is unknown.
As we all know, there is still no cure for HIV. The only person ever to have been cured of HIV is the “Berlin” patient, who effectively had a complete immune system transplant as part of cancer treatment. He was transplanted with cells from a donor who happened to be resistant to HIV infection due to a genetic mutation in their T cells.
In everybody else, HIV persists despite long term treatment. If treatment is stopped, viral rebound (measurable virus in the blood again) occurs after three to four weeks. In people who started their treatment very early after contracting HIV, the time to rebound is longer, but it still happens. It’s because there is a reservoir of HIV in parts of the body that are not able to be reached by current treatments.
So where is cure research heading?
It’s not bone marrow transplants–there have been several attempts to replicate what happened in the Berlin patient, but so far these have been unsuccessful.
It’s not adding more antiretrovirals–studies adding a fourth drug to a successful three drug regimen have not resulted in a cure.
There are two areas of cure research that are looking promising. The first is the “shock and kill” approach, which tries to get HIV out of its hiding places into the open, then destroying it. The second is gene therapy, which could well be a future cure, so watch this space!
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