HIV patient cured with stem cell transplant?

13 December 2010

In the year 2007 an HIV-positive American citizen named Timothy Ray Brown, who resides in Berlin, Germany underwent a stem cell transplant after being diagnosed with a particularly nasty form of cancer called acude myeloid leukemia. AML is a sufficiently specific syndrome that there are a couple of good treatment protocols for it, among them a stem cell transplant to replace the malfunctioning cells in the patient's bone marrow which manufacture defective blood cells. Now, here's where it gets interesting: the donor of the stem cells had a very specific genetic mutation which results in cells of the individual's immune system lacking a receptor site called CCR5 used by HIV when infecting macrophages. Due to the fact that most strains of HIV that medical science knows about require that this receptor site be functional, this renders people with such a mutation broadly immune to HIV. "Broadly," because there are some variants which do not make use of the CCR5 receptor site - TANSTAAFL.

Now, three years after the stem cell transplant, the latest batch of peer-reviewed papers make the claim that Brown is cured.

Prior to the transplant his immune system (compromised though it was) was wiped out with a combination of chemotherapy and full body irradiation; immune cells are kind of fragile in certain ways, so he was reduced to what amounts to an unprotected state. Then the stem cells were injected into his body, where they took up residence and began differentiating into the requisite fleets of cells that produce a human immune system, modulo CD4 cells which don't have functioning CCR5 receptor sites. Immunosuppressive treatment was begun to prevent rejection of the stem cell infusion and periodic cell biopsies were taken to gauge how well Brown's immune system infrastructure was being replaced. Shortly after the transplant was performed (an exact time reference wasn't given in this article), Brown's CD4 cell count was double that of non-HIV positive patients, and now almost four years after the transplant tests for the presence of the virus as well as the presence of compromised cells came back negative, with a very low concentration of HIV antibodies in serum. It is also noted that variants of HIV which are CXCR4 receptor-specific were not found in the patient's system following the transplant, strongly suggesting that the viral concentration was eradicated.

Something I found strange about an interview with Brown a few days ago, and I'm not yet sure of how to interpret it, is that someone asked him if it would have been preferable to live with AIDS rather than have it apparently cured during treatment for leukemia with a stem cell transplant. That's kind of a back-handed thing to say, I think.

No matter how you cut it, I think this represents a significant advance in the field of biotechnology, and I think a lot of us would like to get our hands on a couple of papers written about the Brown case to get more hard information. Add this to your daily news crawl, folks, it's got a lot of potential.