Man unexpectedly cured of HIV after ordinary stem cell transplant

This is how a human immune cell (blue-green) attacked by HIV particles (yellow) looks under a microscope. Photo: NIH-NIAID / Image Point FR / BSIP / Universal Images Group via Getty Images

As explained by New Scientist, five people had previously been cured of HIV thanks to stem cell transplants from donors with a rare genetic feature. They had a mutation in both copies of the gene responsible for producing a protein called CCR5, which the HIV virus uses as an 'entry gate' to penetrate and infect immune cells.

Scientists concluded: since the mutation completely removes this protein from cells, the virus simply has no way to enter. Therefore, it was believed that having two copies of this mutation, which makes cells impervious to the virus, was critically important for overcoming the disease.

But last year, this theory was shaken. The sixth person, dubbed the 'Geneva patient,' lived without the virus for more than two years, even though he received stem cell transplants without this mutation (and thus with the presence of the CCR5 protein). This suggests that blocking the protein is not the only path to recovery. However, many scientists are still cautious: they believe that two years without the virus is still too little to confidently state that the patient is truly healthy.

Patient's Story

However, the latest case significantly changes the situation and provides strong reasons to believe that the 'Geneva patient' was indeed cured. This new story began in October 2015, when a 51-year-old man with leukemia and HIV underwent chemotherapy to destroy the vast majority of his own immune cells.

This was done to make space for a transplant of donor stem cells, which were intended to form a new, healthy immune system in his body. Since an ideal donor with a full CCR5 mutation could not be found, doctors used an available option with a partial mutation.

At the time of the operation, the man was receiving standard antiretroviral therapy (ART) — a combination of drugs that reduce the viral load to an undetectable level, preventing its transmission to others, and also reducing the risk of new donor cells becoming immediately infected.

But approximately three years after the transplant, the patient decided to discontinue ART. As he explained to the doctors, enough time had passed since the transplant, the cancer was in remission, and he always had an inner feeling that the treatment would work.

Soon after stopping the medication, blood tests showed a complete absence of viral markers. Seven years and three months have passed since then — a period fully sufficient to officially consider the patient cured. This is the second-longest result among all seven people who have managed to get rid of HIV (the record holder remains a patient with a 12-year remission).

According to doctors, this case is truly impressive: just a decade ago, the man had meager chances of survival due to oncology. However, today he has returned to a full, healthy life without the need for daily medication.

Mechanism of Recovery

As the publication notes, new data are prompting scientists to reconsider the mechanism of treatment. Previously, it was believed that to overcome the disease, donor cells must be completely impervious to the virus. The logic was that the virus, lurking in the body after chemotherapy, would simply have no one to infect, and the infection would die out on its own due to a lack of targets.

However, the new case suggests a different scenario. The crucial role is played by the reaction of donor cells to the remnants of the patient's own immunity. Due to a different set of proteins on the cell surface, the donor immunity recognizes the old host cells as a threat. As a result, it destroys them (along with the virus contained within) so quickly that the infection simply does not have time to spread to the new immune system.

What Does This Mean for the Future?

This discovery expands the pool of potential donors for people requiring stem cell transplants. However, scientists warn: this is not a guarantee of success. For everything to work, many genetic factors of the donor and patient must perfectly match.

Furthermore, the protagonist of this story did have one copy of the beneficial mutation, which might have simplified the recovery process. Therefore, if there is a choice, doctors still advise looking for donors who are completely resistant to HIV.

Experts also remind that stem cell transplantation remains a very risky procedure, threatening with fatal infections. It is only suitable for those with severe forms of cancer for whom this operation is critically necessary.

For most people with HIV who do not have cancer, antiretroviral therapy remains the safest and most effective method of controlling the virus. Nevertheless, science continues to advance, exploring methods of genetic engineering and vaccination for the ultimate victory over the disease.

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