Two HIV positive patients now virus-free
This story has been receiving a lot of press lately; here is a link to a report in the Huffington Post earlier this week. Researchers at Harvard Medical School held a press conference at an International AIDS conference to announce that two HIV positive patients now have no traces of the virus in their systems, following stem cell transplants for Hodgkin’s Lymphoma. The first proof of concept for this approach detailed the case of a German HIV positive man who became HIV negative following a stem cell transplant. In that case, the patient was apparently cured because the blood cells of some individuals are inherently resistant to HIV infection. The transplant procedure in the Berlin patient essentially replaced his HIV susceptible blood cells with cells that are resistant. Long time readers of BIO230 may recall this comment thread discussing our limited options in developing a cure for HIV, however with the apparent efficacy of high dose antiviral medications, some options for treatment beyond simply keeping the virus at bay might now be available. What makes this new report unique is that the two patients at Harvard Medical School did receive any transplanted blood cells with any special anti-viral properties. Instead, the two patients were maintained on high doses of standard anti-viral medications during the transplant procedure.
Transplant as a route to HIV cure is unlikely to become a mainstream alternative in the immediate future unless some hurdles can be cleared. If the recipient is not an exact match to the donor, the potential for tissue rejection is serious and requires the use of potent immunosuppressant drugs to prevent rejection. These drugs on their own will make the patient particularly susceptible to infection. Transplant of blood cells brings about another risk of rejection as well, as the transplanted blood cells can in effect “reject” the recipient’s own cells in a condition called “graft-vs-host” disease if they are not correctly matched. Further use of immunosuppressant drugs can help this, but hinder the ability to fight off the HIV still in the system.
One way to try and solve the tissue match issue is to potentially draw donor stem cells from the patient himself, culture them in the laboratory to ensure that they are virus free, and then reintroduce them back into the patient in combination with antiviral medications. The biggest obstacle with this approach is ensuring the virus free status, as HIV is renowned for its ability to remain undetectable in a patient for an extended period of time. Indeed, the two patients described in this news alert are unlikely to truly be described as “cured,” but instead will be described as “virus-free” as they are followed up.