Curing HIV?

In early 2009, researchers described an HIV-infected man with acute myeloid leukemia (AML) who had achieved drug-free virologic control for at least 20 months after receiving a stem-cell transplant from a donor who was homozygous for the CCR5 Δ32 allele (JW AIDS Clin Care Feb 13 2009). Now, investigators describe this patient at 45 months of follow-up.

Prior to transplantation, the patient underwent conditioning with cytotoxic agents, total body irradiation, and antithymocyte globulin. On the day of transplantation, he stopped all antiretroviral therapy (ART) and has not reinitiated it. At 13 months, his AML relapsed, he received another intensive conditioning regimen (this time including gemtuzumab, an anti-CD33 monoclonal antibody that was withdrawn from the U.S. market in 2010), and he received a second transplant from the same donor.

In the 45 months since the initial transplantation, the patient's blood and gut mucosa have been reconstituted with CCR5-negative donor CD4 cells. Notably, his new immune system is not impervious to HIV infection: His CD4 cells express the CXCR4 coreceptor and can be infected ex vivo with an exogenous X4-tropic HIV clone. Nevertheless, the investigators have not found any signs of HIV in his blood, gut mucosa, bone marrow, cerebrospinal fluid, or brain (the last of which was biopsied because of leukoencephalopathy, which turned out to be transplant-related). Moreover, his titer of HIV-specific antibodies has continued to decline over time, providing further evidence that viral antigen is no longer present.