Stem Cell Transplant Cures HIV in Third Patient, Alternative to ART

An article published in Nature on February 20, 2022, revealed that a third patient has been cleared of HIV cells, essentially curing the patient, after a stem cell transplant with HIV-resistant stem cells. This treatment may be an improved alternative to antiretroviral therapy (ART); however, there are some associated risks.

The third patient — called the Düsseldorf patient — comes after the Berlin and London patients who have previously been cured. According to a news article in Nature, the Berlin patient, Timothy Ray Brown, was the first to be treated for HIV using a stem cell transplant in 2007. Brown discontinued ART after the treatment and was HIV-free until he died. More recently, the London patient, Adam Castillejo, was treated with a stem cell transplant in 2019 and appeared cured.

It is important to note that the transplants were done for patients with acute myeloid leukemia, for which stem cell transplant is a standard treatment.

According to the Nature publication and news article, stem cell transplants for HIV begin like all other stem cell transplants — by destroying the unhealthy stem cells or bone marrow in the recipient. When searching for a donor, clinicians look for patients with a CCR5Δ32/Δ32 genetic mutation. The Nature article notes that this genetic mutation “prevents the CCR5 cell-surface protein from being expressed on the cell surface. HIV uses that protein to enter immune cells, so the mutation makes the cells effectively resistant to the virus.”

The Düsseldorf patient had previously been using antiretroviral therapy to suppress HIV, resulting in low extremely low HIV levels. The patient was treated with a stem cell transplant in 2013 from a donor with the CCR5Δ32/Δ32 genetic mutation.

While monitoring the patient, researchers collected tissue and blood samples. Within five years after the transplant, researchers found evidence that HIV DNA and RNA were still in the patient’s body but did not replicate. At this point, researchers — in an attempt to determine if the patient could stop taking antiretroviral therapy — transplanted immune cells into mice, finding that the virus failed to replicate.

While these three individuals have been cured, the Nature news article notes that it was a complex and lengthy process. Researchers assume this treatment will not be implemented for HIV patients without leukemia as it is still a high-risk process. Additionally, research must be done to determine the effects of chemotherapy on the viral load.