Image credit: NIAID | Flickr
On the face of things, it seems to be a scientific miracle, not one, but two patients recently announced to be showing signs of remission from HIV after receiving stem cell transplants.
The first to be announced was the anonymous “London patient” described in Nature on the 5thof March, and announced recently at the annual Conference on Retroviruses and Opportunistic Infections. The second was the “Dusseldorf patient” also announced in a recent conference. The London patient has been off antiretrovirals for 18 months, the Dusseldorf patient has been off them for 3 months.
This is not the first time that a patient has been in long-term remission of HIV, in 2008 at the very same conference, it was announced that Timothy Ray Brown, sometimes known as “the Berlin patient” was in remission. Eleven years later he was at the conference to watch Professor Ravi Gupta, the researcher behind the recent breakthrough of the London patient, announce his news to a packed auditorium in Seattle.
These three patients all have the same treatment method in common, they all received a stem cell transplant from a donor with a genetic mutation known as CCR5-delta32. This rare mutation in the CCR5 gene confers the owner with a resistance to HIV, as it produces a rare cell surface receptor which blocks HIV attachment to the cell.
Another thing that all three of these patients shared was a life-threatening cancer on top of their HIV. Timothy Ray Brown was suffering from leukaemia, the London patient was suffering from Hodgkin’s lymphoma. Stem cell transplants were carried out as a last resort to save their lives after other treatment methods had proven ineffective, and donors with the advantageous genetic mutation were selected for the transplant. It is a very unique set of circumstances to come together, which is why it has been such a long time between the announcement about Timothy Ray Brown, and the London and Dusseldorf patients. There are other patients who have had the transplants, but not yet come off antiretroviral drugs, so there may yet be more similar stories in the future.
Sadly this does not herald a ‘cure’ for all sufferers of HIV, for a number of reasons. Firstly, the procedure is dangerous, with between 10% and 20% chance of death. The wiping out of the existing immune system can kill the patient, as can failure in the transplant, as can host-donor rejection. This also leads to the procedure being very costly. This is why it is, and is likely to remain, a last chance effort for those rare HIV patients who are unfortunate enough to have aggressive cancers.
Another problem is that of demographics. Despite successful efforts to reduce infection rates, Africa is still the home to the majority of those living with HIV, with more than 1 million people living with the disease in the African continent. The CCR5 genetic mutation required for the procedure is not only extremely rare, but is also only found in European populations, providing additional logistical and scalability issues for treating those in Africa.
HIV is not the death sentence it once was if diagnosed and treated appropriately, with antiretroviral drugs allowing those infected to reach old age. For now, they are likely to remain the treatment method of choice for all but a select few HIV patients. More work needs to be done in developing nations to prevent further infections, and make sure those with the disease get treatment. But once receiving treatment, drugs prove to be the most cost effective and scalable option.
That’s not to say that there will not be another option in the future. Each victory is a step forward in research efforts. There may also be the option to utilise CRISPR in the future, not to pre-engineer embyros for resistance like the highly controversial efforts of scientist He Jiankui in China recently, but to treat those who are already infected. It is an area that is likely to keep the scientific community and bioethicists busy for many years to come. For now, those in HIV remission is likely to remain a very small, exclusive club.