By Nicole Xu
HIV, or human immunodeficiency virus, is a tedious, lifelong disease. It spreads through bodily fluids and attacks the immune system, specifically the T cells, so that the body can no longer protect itself from other infections. There is no official cure for HIV, but treatment usually involves a continuous prescription of antiretroviral drugs to slow down the progression of the disease so patients can live longer, healthier lives.
In 2010, Timothy Ray Brown became known to the world as the first person to be cured of HIV. He was diagnosed with HIV in 1995, and then later diagnosed with acute myeloid leukemia in 2005.
To treat his leukemia, doctors decided to proceed with one of the standard treatments for bone cancers, which was to have Brown undergo radiation and chemotherapy followed by stem cell therapy. An allogeneic stem cell transplant utilizes a donor’s stem cells that are transplanted into the patient’s body after intense rounds of chemotherapy. This is a riskier procedure often used on patients who do not respond well to normal treatment and those who are at risk or have already relapsed.
The goal of allogeneic stem cell therapy is for the donor’s healthy T-cells to continue growing in the patient’s body and attack the cancer cells in the patient’s body. Because the T-cells are also the same immune cells that cause the patient’s body to reject the transplant, sometimes the stem cells first have to undergo a process known as T-cell depletion to eliminate T-cells from the donor stem cells to avoid the donor’s immune cells attacking the recipient’s body.
Usually, patients do not find many matches for bone marrow donors, but Brown happened to have a few hundred matches, inspiring his doctor to search for donors that had a mutation in the CCR5 gene. The CCR5 receptor is one of two receptors on white blood cells crucial for HIV to be able to infect immune cells. A change in the receptor allows for HIV resistance. This mutation is caused by the CCR5-Δ32 HIV resistance allele and leads to a non-functional surface protein receptor CCR5.
After receiving two transplants due to a few complications, Brown was able to stop taking antiretroviral drugs for treating his HIV and is now considered to be fully cured of HIV.
Recently, another patient with HIV was treated with the same method of stem cell therapy using stem cells from a donor with the CCR5 mutation. It is too early as of now to declare this second patient cured of HIV as it has only been 18 months since this second patient has stopped taking antiretroviral drugs, but there have been no signs of HIV in the patient thus far. Using genetic techniques to identify mutations that can then be targeted as potential cures is becoming a more popular way of treating difficult diseases, so hopefully HIV can be among those with an absolute cure by utilizing the CCR5 mutation.
References:
Brown, T. R. (2015). I Am the Berlin Patient: A Personal Reflection. AIDS Research and Human Retroviruses, 31(1), 2–3. doi: 10.1089/aid.2014.0224
gknation. (2015, February 26). Allogeneic Stem Cell Transplantation | Leukemia and Lymphoma Society. Retrieved from Lls.org website: https://www.lls.org/treatment/types-of-treatment/ stem-cell-transplantation/allogeneic-stem-cell-transplantation