The scientific community recognizes the seventh person in the world cured of HIV thanks to stem cell therapy.
This case is expected to be reported at the 25th International AIDS Conference in Munich, Germany. The 60-year-old patient, who was diagnosed with HIV, later discovered he had acute myeloid leukemia and underwent a bone marrow transplant in October 2015.
He stopped taking antiretroviral drugs in September 2018 but has remained in a state of viral remission without relapse. Current tests show no detectable HIV in the man’s body.
“When we see patients with prolonged HIV remission without the need for any additional treatment, we can be increasingly confident that humanity can eradicate this virus,” said Dr. Christian Gaebler, a physician and researcher at Charité-Universitätsmedizin Berlin.
However, experts caution that stem cell therapy is only suitable for a select few individuals. These HIV patients all had blood cancers and received transplants to treat malignant diseases. Stem cell transplants carry high toxicity and can be fatal. Therefore, it would be unethical to use them for individuals who only have HIV without cancer or any other condition that necessitates it. The stem cell donors were selected for having specific immune cells that naturally resist HIV.
In reality, HIV remains a challenging disease to cure, as the virus often infects long-lived immune cells that are in a dormant state. At any moment, these reservoirs can awaken and start producing HIV again. Thus, when patients stop their medication, their virus levels can rebound within weeks.
Image showing HIV virus entering T cells (immune cells). (Photo: NIAID).
Stem cell transplants can partially cure HIV, as the chemotherapy and radiation therapy destroy the immune system of the cancer patient and replace it with a healthy immune system from the donor.
In 5 out of the 7 cases cured of HIV using this method, doctors found that the donors had a natural deficiency in both copies of a gene that produces a protein known as CCR5 on the surface of immune cells. Most strains of HIV attach to this protein to infect cells. If CCR5 is non-functional, the immune cells are resistant to HIV.
The donor of the latest German patient had only one copy of the CCR5 gene, meaning the immune cells had only half the normal amount of the protein. The German patient also had one copy of the gene. Combining these two genetic factors increases the chances of a cure.
Currently, the world recognizes 6 individuals cured of HIV through stem cell therapy. The first patient was Timothy Ray Brown, also known as the “Berlin Patient.” This case was announced in 2008 and spurred advancements in HIV research. He passed away in 2020 due to leukemia recurrence.
The second case is Adam Castillejo, or the “London Patient.” He underwent a stem cell transplant for blood cancer and bone marrow in 2016 and stopped HIV treatment in 2017.
In 2018, the world recognized Marc Franke, the “Düsseldorf Patient.” He is considered cured, having stopped antiretroviral treatment in November of that year.
Paul Edmonds, also known as “the Hope City Patient,” is the oldest case of HIV cure to date. He had a stem cell transplant in 2019 and underwent low-intensity chemotherapy. In 2021, he stopped antiretroviral medication without HIV relapse.
The fifth patient lives in New York and is the first mixed-heritage individual cured of HIV. She was diagnosed with leukemia in 2017 and underwent a stem cell transplant supplemented with umbilical cord blood. This allowed the patient to match with more donors.
The most recent patient lives in Geneva. He has stopped HIV treatment since November 2021. Researchers are quite cautious about this case, as his immune cells do not possess the ability to resist HIV.
