Stem cell transplant sends HIV patient into remission as genetic mutation ‘locks door’ on deadly virus

There is fresh hope among almost 40 million people living with HIV across the world after a man received bone marrow from a donor with a genetic mutation that “locked the door” against the deadly virus, preventing cell infection and putting him in remission.

Published in Nature medical journal, lead author Bjorn-Erik Jensen and his team of international researchers describe the case of a 53-year-old HIV patient being concurrently treated for acute myeloid leukaemia in 2011.

During a stem cell transplant for the cancer, the man received bone marrow from a donor with a mutation in the gene for the HIV-1 receptor CCR5, which makes cells resistant to HIV infection.

The HIV became undetectable in the patient’s blood cells so anti-retroviral therapy was stopped in November 2018 to see if the infection would return. The patient remained in remission for another four years.

Dr Jensen said the transplant appeared to suppress the patient’s HIV for nine years, fuelling hopes the success of the procedure would follow that of the famous “London Patient” and “Berlin Patient” who underwent similar treatments.

American man Timothy Ray Brown — otherwise known as the “Berlin Patient” after the city he was living in at the time of his diagnosis in 1995 — was the first person to be cured of HIV.

Like the recent case detailed in Nature journal, Mr Brown received a bone marrow transplant from a donor who was naturally resistant to HIV in 2007 as part of his treatment for acute myeloid leukaemia — the same cancer.

He no longer needed anti-viral drugs and remained free of the virus until his death from cancer in 2020.

The development was followed by the “London Patient” — Adam Castillejo — who has shown no detectable HIV in his system since his own transplant, despite not having received HIV treatment during that period.

Then last year, a US patient with leukaemia became the first woman and the third person to be cured of HIV after receiving a stem cell transplant — this time breaking new ground as the first involving umbilical cord blood — from a donor who was naturally resistant to the virus that causes AIDS.

Dr Ioannis Jason Limnios, from the Clem Jones Centre for Regenerative Medicine at Bond University, said the COVID pandemic had helped illuminate the mechanisms behind how viruses work, saying they use special “door handles” called receptors to get into cells.

“Just as COVID-19 uses the ACE-2 receptor to infect cells of the lungs and other tissues, HIV uses a different receptor called CCR5 to infect cells of the immune system,” he said.

“What happens if the door handle is missing? For about 30 years it has been known that some individuals are resistant to HIV infection because they lack CCR5 receptors on their cells — HIV can’t open the door and get inside.”

Dr Limnios said the last 10 years had been instrumental in the development of stem cell and gene editing technologies, so much so that rather than harvesting stem cells from donors with rare and special genetics, they could now be engineered in specialised facilities.

“This is important and exciting progress in the fight against AIDS,” he said.

“However, the researchers carefully state that HIV remains hidden in other tissues of the body.

“So it’s not yet clear if this type of therapy is a life-long ‘cure’ and the risk of passing on HIV — while extremely low — will never be zero using this therapy alone.”

The apparent stem cell cure is also not without risks or expense. Patients who receive a transplant from a donor face the risk of developing graft-versus-host disease, wherein donor stem cells see the recipient’s tissues and organs as foreign and attack them.

The approach is also too expensive for the 38 million people across the world, many in sub-Saharan Africa, living with an HIV infection — per World Health Organisation statistics.

However, the continued developments in donor and engineered stem cells shows growing promise of a cure for the deadly epidemic that has killed about 40 million people since the first case was detected in humans in 1981.