This week, a publication from BioSpace announced that a second individual has been cleared of HIV in another astounding success for stem cell therapy.
The individual known only as the “London Patient” was treated with a stem cell transplant from donors carrying a rare genetic mutation called CCR5-delta 32 that increases resistance to HIV.
Stem Cell Therapy for HIV
Stem cells can be thought of kind of like the base foundation for your cells. Scientists can introduce a “blank” stem cell to the liver, heart, bone marrow, or almost any other organ, and the stem cell will grow to match the cells around it. This can be incredibly useful for replacing tissues damaged by physical trauma or disease.
Scientists have long been considering how this promising technology might be applied to HIV patients.
In 2007, Timothy Ray Brown, a 40-year-old American man living in Berlin, received a second bone marrow transplant for his acute myeloid leukemia. Brown was also HIV positive, and had been taking antiretroviral medication for some time when he received his cancer diagnosis.
Curiously, after Brown’s second marrow transplant, his HIV-1 infection was found to have cleared. The marrow he received from his donor happened to be CCR5-negative – a genetic mutation that provides a natural resistance to HIV. The combination of antiretrovirals and new marrow seemed to flush the HIV from Brown’s system.
A few years after going off antiretrovirals, trace amounts of HIV were detected in Brown’s blood, but a small enough amount for him to still be considered clinically cured. For more than a decade, he was considered the only person to ever be cured of HIV.
The London Patient
The London Patient, like Timothy Brown, also developed cancer following his 2003 HIV diagnosis. It was an advanced form of Hodgkin’s lymphoma, a cancer that begins in the immune system. Also like Brown, the London Patient undertook antiretroviral therapy for several years before receiving a bone marrow transplant from a CCR5-negative donor in 2016, following a period of chemotherapy.
The London Patient continued to take their antiretroviral medication as usual for another year and four months. They were then taken off the medication to determine if they were truly in remission.
The anonymous patient has been in remission for a year and a half now, and tests confirm that his HIV is more or less undetectable.
Dr. Sharon Lewin is a professor with the University of Melbourne and also the director of the Peter Doherty Institute for Infection and Immunity. She has speculated that the marrow transplants have been effective by providing a resistance to HIV infection, while also targeting and destroying any already HIV-infected cells.
Not a Viable Treatment for Average HIV Patient
Researchers don’t know exactly why yet, but the procedure doesn’t work in some individuals. In addition to that, the potential benefits, when weighed against the risks (which can include serious conditions like graft-versus-host disease), are not necessarily worthwhile.
That’s because for the average HIV patient, the condition is highly manageable with a simple daily tablet treatment. Professionals believe that the treatment used for the London Patient would not be “scalable, safe, or economically viable” for the typical individual with HIV.
Regardless, the breakthrough is extremely encouraging. It represents another big, hopeful step forward in combating a condition affecting over 1 million Americans.
To date, only two individuals have been observably “cleared” of HIV. Do you expect the connection to the CCR5-delta 32 to be relevant to the treatment of average HIV patients in the future? Share your thoughts with Patient Worthy!