An HIV-positive person is sustaining an undetectable viral load without the use of HIV drugs after receiving a bone marrow transplant from a donor who is naturally resistant to the virus. The patient, who received the transplant as treatment for leukemia, has taken no HIV drugs for more than 600 days.
If the patient’s viral load remains undetectable, it would be the first time an HIV-positive person has become HIV-negative, suggesting the possibility that HIV disease may one day be treated and cured with genetic therapies.
Leukemia, a type of blood cancer, is sometimes treated with a bone marrow transplant. The procedure involves killing cancerous bone marrow cells in a patient’s body with radiation and drugs, then introducing new cancer-free cells.
Gero Hütter, a Berlin hematologist, sought out a bone marrow donor in this case with a specific genetic mutation called CCR5-delta 32 — characterized by a lack of chemokine-5 receptors — that renders near-immunity to HIV-1.
HIV-1 enters cells through CCR5 receptors. According to the US Centers for Disease Control (CDC), a person who inherits two copies of the CCR5-delta 32 mutation — one from each parent — has “almost absolute protection” from HIV-1 infection. When a patient has only one copy of the mutation HIV transmission is not stopped but the progression into AIDS can be delayed by up to three years. CDC statistics indicate that the mutation varies wildly among ethnic groups.
In the treatment procedure used by Hütter, “You kill not only the… cancer cells, you’re also killing the HIV cells,” says Chil-Yong Kang, a virologist and HIV researcher at the University of Western Ontario. “When that person got a bone marrow transplant, he’s got a brand new set of lymphocytes [white blood cells of the immune system], which are not infected, so maybe that’s why he was cured.
“If there is a mutation in CCR5, it may not work as a secondary receptor for HIV infection,” he continues. “So if that person was supplied with the mutated bone marrow and if those bone marrow do not have a secondary receptor for HIV… the virus cannot get into the cell and therefore this person is resistant to the virus infection.”
Kang says that just because one patient appears to have been cured of HIV does not mean researchers are on the verge of a cure for everyone.
“You’re in fact scorching a person with radiation and then giving them new cells,” he says. “In theory it may work but who can tolerate that kind of radiation? That kind of treatment is not really recommendable.”
About 30 percent of bone marrow transplant recipients die from the procedure.
Hütter declined comment for this article, saying that his study is to be published in a US scientific journal in the near future.