A Real HIV Cure? Here’s What We Know…
began HIV treatment soon after. About 10 years later, in 2013, he was diagnosed with Hodgkin’s Lymphoma, stage IVb, an advanced stage of cancer that is sometimes seen in patients with HIV infection. Hodgkin’s Disease (Hodgkin’s Lymphoma) is oftentimes curable cancer, but in this case, the disease is diagnosed at an advanced stage. Treatment of this cancer requires multiple strategies, any of which could affect HIV disease. First of all, the treatment of cancer required a stem cell transplant (allogeneic stem transplant). Stem cells are the source of our infection-fighting cells in the body. Blood cells are collected from a matched donor and the stem cells are separated.
Then, radiation or chemotherapy is used to kill the cancerous blood cells in the patient and increase chances the donated cells will be accepted. The patient then receives the donated cells. It is most important to understand that the person who donated the cells to this patient had a genetic modification of a protein that HIV uses to infect cells. This protein is called CCR5 and the virus must attach to this protein on the outside of the cell in order to enter and infect the cell. Because of the altered structure of this protein, due to a genetic mutation present in about 1% of Europeans, the virus cannot attach and infect the lymphocyte. So now, this patient’s blood cells have been replaced with cells that are resistant to HIV infection. The HIV drug Maraviroc (Selzentry) essentially works the same way as this genetic mutation by blocking CCR5 and preventing HIV from infecting cells.
The treatment of the cancer also involved some courses with cancer chemotherapy before the donor cells are administered. The use of these cancer drugs may also have played an important role. Cancer chemotherapy can be toxic to blood cells. However, in this case, it could have possibly been helpful in eliminating cells harboring latent HIV virus, known as the reservoir (See article “Why we haven’t cured HIV Infection” January 4, 2019). Indeed when the researchers performed special tests to produce virus from the reservoir, no virus was produced; a good sign that the reservoir was eliminated. The transplant required immunosuppressive medicines to keep the patient from having a reaction and rejecting the transplanted blood cells.