LONDON • An HIV-positive man in Britain has become the second known adult worldwide to be cleared of the Aids virus after he received a bone marrow transplant from an HIV-resistant donor, his doctors said.
Almost three years after the man received bone marrow stem cells from a donor with a rare genetic mutation that resists HIV infection - and more than 18 months after he came off antiretroviral drugs - highly sensitive tests still show no trace of the man's previous HIV infection.
Dr Ravindra Gupta, a professor and HIV biologist who co-led a team of doctors treating the man, described his patient as "functionally cured" and "in remission", but cautioned that "it's too early to say he's cured".
The man is being called "the London patient", in part because his case is similar to the first known case of a functional HIV cure - that of an American man who became known as the Berlin patient when he underwent similar treatment in Germany in 2007, which also cleared his HIV.
Some 37 million people worldwide are infected with HIV, and the Aids pandemic has killed about 35 million people since it began in the 1980s. Scientific research into the complex virus has, in recent years, led to the development of drug combinations that can keep it at bay in most patients.
Dr Gupta, now at Cambridge University, treated the London patient when he was working at University College London. The man had contracted HIV in 2003, Dr Gupta said, and in 2012, was also diagnosed with a type of blood cancer called Hodgkin's lymphoma.
In 2016, when he was very sick with cancer, doctors decided to seek a transplant match for him.
The donor - who was unrelated - had a genetic mutation known as "CCR5 delta 32", which confers resistance to HIV.
The transplant went relatively smoothly, Dr Gupta said, but there were some side effects, with the patient suffering a condition in which donor immune cells attack the recipient's immune cells.
Most experts say it is inconceivable that such treatments could be a way of curing all patients as the procedure is expensive, complex and risky.
To do this in others, exact match donors would have to be found in the tiny proportion of people who have the CCR5 mutation that makes them resistant to the virus.
But the case offers proof of the concept that scientists will one day be able to end Aids.
"Although this is not a viable large-scale strategy for a cure, it does represent a critical moment," said Dr Anton Pozniak, president of the International Aids Society.