A stem cell transplant to treat leukemia may have resulted in a “cure” for the Geneva patient, the sixth person known to have HIV. Following the transplant and after the antiretroviral therapy was discontinued 20 months ago, the virus has remained undetected in the patient’s blood.
It is noteworthy that, in contrast to the previous five cases, the donor in this instance lacked the mutation associated with reduced risk of catching the infection, which the researchers had specifically sought.
In 2018, the Geneva patient, who had been living with HIV since the 1990s, undertook a stem cell transplant to counter an aggressive form of leukaemia. Following the transplant, the number of HIV-infected cells decreased notably, leading the doctors to ease off on his medication and to end his regimen altogether in November 2021. Later, Institut Pasteur, in collaboration with Institut Cochin and the IciStem consortium, conducted tests which could not detect any viral particles, latent reservoirs or elevated immune activity against the virus, 20 months after his treatment.
The Geneva patient’s case marks a sixth instance of remission from HIV, with the unique difference being that his cells continue to be susceptible. Due to this, the researchers cannot entirely discount the chance of his HIV returning. Alexandra Calmy, HIV/AIDS Unit Director at the Geneva University Hospitals, expresses optimism that the exploration of this special case may one day yield a more permanent cure from HIV. She said in a release, “Through this unique situation, we are exploring new avenues in the hope that HIV remission or even cure will one day no longer be a one-off occurrence.”
The six patients who have achieved HIV remission so far have all needed a stem cell transplantation to treat their cancers. For the first five of these cases, the respective medical teams identified donors with the CCR5 delta 32 mutation, which is thought to be associated with a decreased vulnerability to HIV.
Individuals infected with HIV have lower immunity due to the virus attacking their CD4 immune cells. In order to get into these cells, HIV requires surface receptors; however, people who receive the CCR5 delta 32 mutation from both sets of their parents don’t form these receptors, leaving the virus unable to enter the cells. If one parent passes on the mutation, there will be fewer receptors, thus reducing the chance of getting the infection.
Approximately 1% of the world population possesses two copies of the CCR5-delta 32 mutation- meaning that it was obtained from both of their parents. Additionally, the other 20% carry one copy of this gene, particularly those of European origin.
It is highly improbable that stem cell transplants could provide a widely viable solution for HIV patients. There are presently 38.4 million people living with the virus, an inconceivable number to find a compatible donor for, and many of these may not be suitable for the CCR5 delta 32 mutation that is primarily found amongst Caucasian populations. Furthermore, the process of transplantation carries its own risks and the virus may mutate to infect cells further down the line, even in the presence of donor cells.
Instead of relying on other methods for treating HIV across the globe, antiretroviral therapy is successfully used to suppress the replication of the virus. This allows an increase in the amount of CD4 immune cells, thus reducing the amount of viral particles to an undetectable level, eliminating the risk of transmission.
Anti-retroviral therapy for HIV needs to be taken life-long. These drugs cannot completely rid a person’s body of the virus, and so when they are stopped, the viral count tends to rise again. Despite not eliminating the virus, these drugs do effectively prevent the progression of HIV to the Acquired Immunodeficiency Syndrome (AIDS) stage.
In 2007 and 2008, Timothy Ray Brown, also known as the Berlin patient, became the first person to achieve remission of HIV, after receiving two stem cell transplants. Sadly, he passed away in 2020 due to cancer, yet he had remained free of this virus since his initial success.
In 2019, the success of the Berlin patient was replicated when the London patient, Adam Castillejo, was declared free of the virus.Two more cases, known as ‘The City of Hope patient’ and ‘New York patient’, emerged in 2022.
A highly promising medical breakthrough occurred when a New York patient became the first mixed-race individual to be completely cured of HIV after receiving a dual stem cell therapy consisting of umbilical cord stem cells from a neonate and adult stem cells, which requires less stringent HLA matching. The implications of this are far-reaching, as this revolutionary treatment could now be available to all races in the future.
The revolutionary treatment of combining umbilical cord stem cells taken from a neonate and adult stem cells, which requires less stringent HLA matching and used to completely cure a New York patient of HIV, is hugely promising. This has far-reaching implications as it could make this new type of therapy available to all races in the near future.