March 5 (UPI) -- A decade after the first human was believed cured of HIV through a transplant, another appears to have beaten the virus in a similar fashion, researchers reported in the journal Nature.
A British man who received a stem cell transplant has been in HIV remission for 18 months, doctors said in the report late Monday. It's a major breakthrough in HIV-AIDS research, but doctors say it's too soon to be considered a cure.
The man received a stem cell transplant involving virus-resistant cells, which put his HIV in remission. He was diagnosed with HIV in 2003 and non-Hodgkin's lymphoma in 2012. Doctors said the stem cells were transplanted from an HIV-resistant donor, and the treatment appears to have beaten back both his HIV and the cancer.
The man is just the second in the world to show no traces of HIV after such a procedure. The first, Timothy Brown, or the "Berlin patient," received a bone marrow transplant from a resistant donor in 2009 and is now HIV-free.
"I think this is really quite significant. It shows the Berlin patient was not just a one-off, that this is a rational approach in limited circumstances," said Daniel Kuritzkes, chief of infectious diseases at Brigham and Women's Hospital. "Nobody doubted the truth of the report with the Berlin patient, but it was one patient. And which of the many things that were done to him contributed to the apparent cure? It wasn't clear this could be reproduced."
Publicly, scientists describe the case as long-term remission rather than a cure. They say it's hard to call it a cure when there are only two known instances.
As part of his cancer treatment and transplant, the London patient received a malfunctioning CCR5 gene, which creates a protein crucial for HIV to invade blood cells, researchers said. Brown received a transplant without functioning CCR5 genes.
The London patient, who has not been named, told The New York Times he feels a "sense of responsibility to help the doctors understand how it happened to so they can develop the science."
Several so-called "Boston patients" received stem cell transplants with functioning CCR5 genes and showed marked improvements, going months without treatment. But their progress was only temporary, researchers believe, because an aberrant gene was necessary for a long-term cure.
Such transplants are risky and rare and usually done only when the patient already has cancer. Donors have to be a genetic match and carry the malfunctioning CCR5 gene.
Still, the findings could inspire new efforts toward a true cure.
"These new findings reaffirm our belief that there exists a proof of concept that HIV is curable," International AIDS Society president Anton Pozniak said in a statement. "The hope is that this will eventually lead to a safe, cost-effective and easy strategy to achieve these results using gene technology or antibody techniques."