The man is being called "the London patient", because his case is similar to the first known case of a functional cure of HIV - in an American man, Timothy Brown, who became known as the Berlin patient.
Regular testing confirmed that the patient's HIV (human immunodeficiency virus) viral load remained "undetectable", and he has been in remission for 18 months since ceasing ARV therapy (35 months post-transplant), according to the press release. The patient ceased taking medication to treat HIV in September 2017 and has been in remission since.
"This poses a particular challenge in developing countries", where millions are still not receiving adequate treatment, he added.
Some 37 million people worldwide are now infected with HIV and the AIDS pandemic has killed around 35 million people worldwide since it began in the 1980s. Almost 1 million people die every year from HIV-related causes.
Publicly, researchers have dubbed the treatment plan a "cure", though there's a major caveat: Bone marrow transplants are risky procedures with side effects that can last a lifetime.
Most experts say it is inconceivable such treatments could be a way of curing all patients.
"We can try to tease out which part of the transplant might have made a difference here, and allowed this man to stop his anti-viral drugs".
"Personally I think there is probably some virus somewhere in the body, but it's absolutely trapped", says Deeks.
One of the reasons HIV is so hard to eliminate is that the virus' normal lifecycle includes integrating a copy into the host cell's DNA.
The male London patient, who has not been named, was diagnosed with HIV in 2003 and advanced Hodgkin's lymphoma in 2012.
Prof Eduardo Olavarria, also involved in the research, from Imperial College London, said the success of stem cell transplantation offered hope that new strategies could be developed to tackle the virus. Transplant performed with mutant immune cells resistant to HIV. That's too soon to label the treatment - which used hematopoietic stem cells from a donor with two copies of an HIV-resistance gene - as a cure, researchers said Tuesday in a study in the journal Nature. For people without cancer, treatment with antiretrovirals in the long term is preferable to even a short combination of chemotherapy and stem cell transfer.
The team also found that the patient's white blood cells are resistant to CCR5-dependent HIV strains, which suggests the donated cells have become engrafted. To treat the cancer, the London patient agreed to a treatment called a stem cell transplant.
Similarly, Timothy Ray Brown, the Berlin Patient, had been living with HIV and routinely using antiretroviral therapy when he was diagnosed with a different disease, acute myeloid leukemia. He and Brown are the only cases of long-term HIV remission ever recorded.