To do this in others, exact match donors would have to be found in the tiny proportion of people - majority of northern European descent - who have the CCR5 mutation that makes them resistant to the virus. More than 18 months after, the unidentified man dubbed the "the London patient" came off antiretroviral drugs-tests still show no trace of the man's previous infection.
Mr Brown said he would like to meet the London patient and would encourage him to go public because "it's been very useful for science and for giving hope to HIV-positive people, to people living with HIV".
Only a second person in the world diagnosed with the most common type of human immunodeficiency virus (HIV) might have been cured of the infection after receiving a stem cell transplant, CNN reported, citing a study.
While some commentators are calling this a "cure" for HIV, the scientists who performed the experiment say it's too soon to say that.
Since the beginning of the AIDS epidemic, more than 70 million people have been infected with HIV and about 35 million people have died because of complications from the viral illness.
Although Brown almost died after he was given strong immunosuppressive drugs and was put into a coma, the "London patient" did not come that close; he suffered from Hodgkin's lymphoma and received a similar bone-marrow transplant to Brown's, but the immunosuppressive drugs he received were gentler. "We can't detect anything", Ravindra Gupta, the doctor who co-lead the man's treatment team, told Reuters.
"They used a reduced intense conditioning regimen but I think that had no influence on the outcome", he said. Rather than do whole-body radiation to kill the patient's existing immune cells, the patient was given chemotherapy and drugs that specifically targeted his immune cells prior to the transplant.
"There's good reason to hope that it will have the same result", Andrew Freedman, a clinical infectious diseases physician at Cardiff University who was not involved in the study, tells Nature.
Most experts say it is unlikely such treatments could be a way of curing all patients. The London patient, who had Hodgkin's lymphoma, is the first adult to be cleared of HIV since Brown.
CCR5 is on the surface of white blood cells, and HIV uses it to enter a cell. After chemotherapy, he underwent a stem cell transplant in 2016 and subsequently remained on antiretroviral therapy for 16 months. He was called the "Berlin patient" and was later identified as Timothy Ray Brown.
The CCR5 gene was thrust into the global spotlight recently by the revelation that a Chinese scientist had attempted to edit human embryos to create the same deletion, with the hopes of creating babies that were immune to HIV. Yet Brown's case remained the lone success since then.
Replacing immune cells with those that do not have the CCR5 receptor appears to be key in preventing HIV from rebounding after the treatment.
But it also effective against cancer because the new "graft" cells work better against the disease.
However, now that science has determined that the earlier Berlin patient's HIV cure wasn't merely a unusual fluke, it could open up the doors to new gene-level treatments for the disease.