"We've always wondered whether all that conditioning, a massive amount of destruction to his immune system, explained why Timothy was cured but no one else", AIDS expert Dr. Steven Deeks, who has worked with Brown medically, told NYT.
A man in Britain has become the second known adult worldwide to be cleared of the virus after he received a bone marrow transplant from an HIV-resistant donor, his doctors said. "I think it is important to reaffirm that this is real and it can be done", Gupta said.
Nearly 12 years after the first known patient to reportedly be cured of HIV, scientists believe there is another.
Both the first patient to be cured of H.I.V., Timothy Ray Brown, who is now 52 and was cured in 2007, and the new patient, whom scientists refer to as the "London patient", were afflicted with forms of cancer and were given bone-marrow transplants meant to treat their cancers, not the H.I.V virus, according to The New York Times. "Continuing our research, we need to understand if we could knock out this receptor in people with HIV, which may be possible with gene therapy", he added. As of now, people who have been diagnosed with HIV have to take antiretroviral medication to suppress the virus for the rest of their lives. About 37 million people worldwide now have HIV, and the AIDS virus has killed about 35 million since taking off in the 1980s.
He was diagnosed with HIV in 2003 and started taking drugs to control the infection in 2012.
Later that year, he was diagnosed with advanced Hodgkin's Lymphoma, a deadly cancer. The donor had this double copy of the mutation.
Researchers also noted that chemotherapy alone may contribute to eradicating HIV infection, as it kills dividing cells and allows for replacement of immune cells with cells that do not have the CCR5 receptor.
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. These mutations are in a gene called CCR5, which HIV normally recognizes in immune cells and uses like a key to enter and infect them.
Regular testing confirmed that the patient's viral load remained undetectable, and he has been in remission for 18 months since ceasing ARV therapy (35 months post-transplant). Since then, researchers have been trying to replicate the procedure.
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.
Such transplants are risky and have failed in other patients.
The London Patient was given stem cells from a donor with genetic resistance to the disease. Both Brown and the London patient are testament to how effective such strategies in modifying CCR5 can be in thwarting HIV.
Gupta went on to tell the outlet that the patient was "in remission" and "functionally cured"; however, "It's too early to say he's cured" completely, said the doctor.