Doctors say they’ve likely cured yet another person of HIV using a specialized form of stem cell transplant. The patient has remained HIV-free for six years and is the first known woman to have successfully undergone the procedure. The doctors used a novel technique that transplanted stem cells from a relative and a donor’s umbilical cord blood at the same time—a technique that could make these transplants more widely feasible.
The patient’s doctors earlier detailed her ongoing case at an HIV-related science conference last year. On Thursday, they published a peer-reviewed paper on her case in the journal Cell. Following the tradition of other patients who have been treated and likely cured with donor stem cells, the woman is only identified as the New York patient. She’s thought to be one of five people who have been successfully treated this way, though it’s still early to know for sure in some of these cases. She is the first woman of color in this exclusive group, identifying as mixed race.
According to the paper, the woman’s HIV was kept well-controlled once diagnosed. Unfortunately, four years after her diagnosis, she also developed acute myeloid leukemia, a form of cancer that affects white blood cells. The combination of the two diseases made her a suitable candidate for a unique procedure, however. Stem cell transplants are often used to treat leukemia, since they can restore a person’s immune system following treatment that tries to eradicate the cancer. By transplanting stem cells from someone carrying a mutation that naturally makes them resistant to HIV infection to someone who also has HIV, the hope is that you can transfer over that resistance as well, allowing their bodies to permanently get rid of the virus.
To date, these transplants have largely relied on stem cells taken from adult donors with the mutation, called CCR5-delta32/32. But the woman was enrolled in a study that’s testing out the use of cord blood, the IMPAACT P1107 trial. Donor stem cell transplants require compatibility between the donor and recipient, and compatible adults carrying the CCR5-delta32 mutation are an especially rare type of donor. But donor stem cells taken from umbilical cord blood only need to be a partial match to the recipient, which should make them a more practical option. That’s especially important for racially diverse populations, since they’re much less likely to find someone compatible in the first place. To improve the odds of the procedure working, the doctors also transplanted stem cells from a family member who was a partial match to the woman, with these cells meant to act as a temporary bridge before the other stem cells would fully rebuild her immune system.
The woman received the transplant in August 2017. She’s since experienced some complications possibly related to the procedure (mainly symptomless infections), but her HIV levels remained undetectable while she stayed on treatment. Roughly three years later, doctors decided to stop HIV treatment altogether. Now, nearly six years after the transplant, the woman still shows no signs of either her cancer or HIV infection returning.
“This woman is doing exceptionally well. She is free of both cancer and HIV, and is travelling and enjoying her life,” study author Yvonne Bryson, a researcher at the University of California, Los Angeles, told Gizmodo in an email. Other members of the team include physician-scientists from Johns Hopkins University, Weill Cornell Medicine, and New York-Presbyterian hospital.
These treatments are sadly not scalable as a standalone HIV cure. Stem cell transplants are a risky procedure that can have serious, even life-threatening complications. These risks are outweighed by the benefits they can provide to some people with leukemia or similar conditions, but not for the average person with HIV, which can be managed effectively with medication.
In those living with HIV who develop these conditions, though, these transplant procedures could very well become a two-for-one cure. Right now, it’s a major challenge to find compatible people, but if cord blood does prove to be a reliable source of these unique stem cells, that should open up the pool of donors. It’s also possible that ongoing research will lead one day to treatments that can create this resistance to HIV in people without the use of a transplant, Bryson says.
“Potentially in the future there will be ways to make one’s own cells resistant—i.e. gene therapy, etc.—or to combine the reduction of viral reservoirs with acquired host resistance by HIV vaccine immunotherapy,” she said.
The authors do note in the paper that one other person has undergone this procedure, but the transplant failed within a year’s time. The man’s cancer returned, and he continued to show signs of HIV in his system. So scientists may still have to find ways to improve its success rate. Another concern is finding and establishing an ample enough supply of these rare cord blood donors. With their current protocol, the team was able to identify 300 units of eligible cord blood, enough to help someone in immediate need of a transplant. But they say that support from communities and governments will be needed to ensure a continuous pipeline.
This article has been updated with comments from one of the study’s authors.