Finding a cure for HIV infection; promise or reality?
(Note: all the sources listed in the “Balanced” section)
Anti-retroviral therapy (ART), or highly-active-antiretroviral
therapy (HAART), is effective in halting progression of HIV infection. However,
the HIV virus, despite of the treatment, remains hidden in the human body. In
2017, existing medications for the treatment of HIV infection such as Gilead’s
Genvoya and Merck’s Isentress had annual sales of $3.67 billion and $1.2 billion,
respectively. Notwithstanding their commercial success, these medicines do not
cure the disease. The HIV virus often remains hidden in the human body in
reservoirs such as dendritic cells, macrophages, and CD4+
lymphocytes. Since HIV was first detected in 1983, the medical community have
intensively searched for a cure for HIV infection.
The
Story of the Berlin Patient. In 2007, Timothy Ray Brown, an American studying in Berlin,
Germany, was treated with a hematopoietic stem cell transplant. Two years
earlier, Mr. Brown had been diagnosed with a type of blood cancer known as acute
myeloid leukemia (AML). Besides its cancer diagnosis, Timothy was infected with
the Human Immunodeficiency Virus (HIV). Dr. Gero Hütter, a German doctor from
the Charité Hospital, Berlin University of Medicine, performed the transplant. At
the time, Dr. Hütter had never treated an HIV patient before Timothy, but he
had learnt about a rare genetic mutation causing natural resistance to HIV
infection. Based on this information, Dr. Hütter found a stem-cell donor
carrying this specific mutation. He performed the transplant on Mr. Brown using
these mutated cells.
The procedure resulted in a surprising outcome as Timothy’s HIV
infection disappeared after the transplant. The HIV virus could not be detected
on his blood, not even with the most sensitive diagnostic techniques such
polymerase chain reaction (PCR) methods. Timothy Ray Brown was cured of his HIV
infection. He became famous in the medical community. Timothy is now known as
the Berlin patient (https://www.youtube.com/watch?v=f6DXqGZt_Fw). The story of the Berlin patient triggered significant interest in both academy and industry, setting off a golden rush to find a sterilizing cure for HIV infection. Timothy’s transplant treatment was done from a donor carrying a mutation in a gene known as CCR5, which happens to be the site of entry utilized by HIV virus to infect immune system cells (New England Journal of Medicine 2009, 360, 692-698). The CCR5 protein receptor is expressed on the surface of lymphocytes T, which are the predominant target cell for the virus. Two cell receptors, CD4+ and CCR5, are utilized by HIV to enter the cell. The virus cannot enter and infect cells with a defective CCR5 receptor. As a result, HIV cannot find a home, the patient’s viral load gradually decreases, and eventually the virus fizzles out. This is probably what transpired during Mr. Brown’ treatment procedure. The fact of the matter is that the virus became undetectable in Timothy’s body. He stopped taking any medication for HIV, although he continued to undergo treatment for his blood cancer. Since then, Timothy has remained HIV negative. He has been cured from his HIV infection.
