A woman has been cured of HIV after receiving a new stem cell transplant that used cord blood. She’s thought to be the third person ever to be cured of the virus.
The woman, who has not been publicly named, was the subject of a presentation on Tuesday at the Conference on Retroviruses and Opportunistic Infections. The patient is of mixed race, which scientists say creates the possibility that other people from diverse racial backgrounds may be cured of HIV.
The two previous patients who were cured of HIV received bone marrow transplants that require a close genetic match with the patient, according to a press release from Weill Cornell Medicine, where the woman was treated. But cord blood is more easily accessible and doesn’t need as close of a match.
The woman had leukemia and received the cord blood treatment for her cancer from a partially matched donor (meaning, they weren’t a perfect match in race and ethnicity). She also received blood from a relative to help her body mount temporary immune defenses during the transplant.
The woman’s story is fascinating and raises a lot of questions about a disease that’s incurable for most people. Here’s what you need to know about this treatment.
What is HIV, again?
HIV, which is short for human immunodeficiency virus, weakens your immune system by destroying certain cells that fight disease and infection, according to the Centers for Disease Control and Prevention (CDC). If HIV isn’t properly treated, it can lead to acquired immunodeficiency syndrome (AIDS).
HIV can cause no symptoms, although it may cause symptoms two to four weeks after someone is infected, the CDC says. Those can include:
- Fever
- Chills
- Rash
- Night sweats
- Muscle aches
- Sore throat
- Fatigue
- Swollen lymph nodes
- Mouth ulcers
Most people contract HIV through anal or vaginal sex, or by sharing needles or other drug injection equipment, the CDC says. While there is no cure that’s considered effective for HIV, it can be controlled with the right medical care.
How do stem cells cure HIV?
It’s a little complicated. At a macro level, stem cell treatments replace someone’s immune system with that of another person’s, says Thomas Giordano, M.D., professor and chief of infectious diseases at Baylor College of Medicine in Houston, who did not work with the patient.
These are “intense treatments that wipe out a person’s immune system—and hopefully the cancer they are treating, too,” Dr. Giordano says. “Since HIV lives in a person’s immune system’s cells, it kills many of the cells that contain HIV. Once you kill the bone marrow, you have to restore it with stem cells, otherwise the person will die since you can’t live without the immune cells, platelets, and red blood cells that your bone marrow makes.”
That’s where a donor comes in. “A transplant alone is not enough to cure HIV—the HIV will come back,” Dr. Giordano says. “It turns out, some people are immune to HIV infection. These people have a genetic mutation that we can detect on tests, called the delta 32 mutation of the CCR5 receptor. It is a pretty rare mutation, and is more common in people from northern European ancestry.”
In this particular case, stem cells from cord blood carried the delta 32 mutation of the CCR5 receptor, says Jing-Mei Hsu, M.D., Ph.D., a stem cell transplant specialist at Weill Cornell Medicine who treated the latest patient cured of HIV. “When the cord stem cell replaces her blood, she now has a blood system that is resistant to HIV infection,” Dr. Hsu explains. “Usually when patients stop taking their anti-viral medication, the HIV becomes quickly detectable. In this case, she is off treatment for 14 months and we can’t detect any HIV even with most cutting-edge and sensitive tests.”
“Strains of HIV require a specific co-receptor to be able to viably infect cells and there are individuals who lack those receptors,” says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security, who did not work with the patient. When someone with leukemia receives the right transplant match, it can “render the patient inhospitable for HIV,” Dr. Adalja says. Meaning, their bodies can no longer support HIV and they are cured of the virus.
This is what happened with the first patient who was cured of HIV, Timothy Brown, aka the “Berlin Patient,” Dr. Adalja explains. He was treated for acute myeloid leukemia (AML) and received a stem cell transplant from a donor who had a rare genetic abnormality that gives the immune cells that HIV targets a natural resistance to the virus, per The Wall Street Journal.
The treatment specifically works by doctors destroying a person’s immune system, usually with chemotherapy. Then, they do the stem cell transfusion that contains HIV-resistant stem cells to essentially replace the old immune system.
The treatment was also successful in 2019 in a man who was later identified as Adam Castillejo.
In the case of this woman, she received cord blood from a donor, along with partially matched blood stem cells from a first-degree relative. She stopped taking antiretroviral therapy, which helps keep HIV from progressing, 37 months after her transplant. It’s now been 14 months since then and she no longer has signs of HIV.
“Curing a woman of mixed racial ancestry is a very important symbolic feat, since most of the people living with HIV in the world are in sub-Saharan Africa and half of the people with HIV in the world are women,” Dr. Giordano says.
Dr. Hsu is cautious about saying that the woman is actually “cured” given that “HIV can hide in patient’s body and resurface later.” As a result, she says, “we still need to continue with close monitoring.”
How effective is it to treat HIV with stem cells?
As a whole, this isn’t an effective treatment. While it has worked twice before it has also failed in at least two other patients.
It’s also a very risky procedure. The treatment can be toxic and even fatal for patients, Dr. Hsu points out. “Strict transplant using stem cell for patient without cancer or non-cancerous condition is too toxic,” she says. Dr. Adalja agrees. “This isn’t a benign type of treatment,” he says.
Patients can also develop intense side effects after undergoing the procedure. Both Brown and Castillejo experienced graft versus host disease, where the donor cells attacked their bodies, and Brown almost died after his transplant, The New York Times says.
A case report published after Castillejo was cured detailed how he lost nearly 70 pounds, and developed hearing loss and several infections.
It’s important to point out, too, that this procedure has only been done in people with leukemia. “This is not something for the general population but for HIV positive persons who happen to a specific type of leukemia and require transplantation,” Dr. Adalja says. “People need a reason for a stem cell transplant outside of HIV.”
What does the future hold for stem cell treatment for HIV?
It’s unclear at this point. There have not been a large number of people treated for HIV using stem cells, and the success rate is nearly equal to the failure rate. However, using cord blood is a newer approach.
“I’m cautiously optimistic, but we need more long-term data,” says Perry N. Halkitis, Ph.D., M.P.H. professor of biostatistics and urban-global public health and director of the Center for Health, Identity, Behavior & Prevention Studies at Rutgers University.
If this does end up being an effective way of eradicating HIV, Halkitis says it can be useful for managing the condition. “Taking a medication every single day can be complicated phenomenon for most people,” he says. “If people are willing to engage in some level of risk that may eradicate HIV from their body, some will likely opt into it.”
Dr. Hsu says that stem cell transplants, which are a form of cell therapy, are getting better. “New advances in cell therapy and gene therapy are striving to provide therapies that can eventually apply to patients who don’t require stem cell transplant,” she says.
Dr. Hsu encourages expectant parents to consider banking their cord blood. “Umbilical cord blood serves as a potent source of hematopoeitic stem cells and can be used to treat various disorders like blood cancers, hemoglobinopathies and immunodeficiency disorders, and inherited metabolic disorders,” she says.
Parents may also consider donating to a public cord bank, where the cord blood could be used by others. “By donating to a public cord blood bank, it opens doors for to help other patients in needs of transplant for so many diseases," Dr. Hsu says. "It certainly also increases the pool of cord blood that can be screened for the rare natural genetic mutation that can be used for HIV-infected patients in need of transplant.”
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