German Man Becomes Seventh AIDS Cure Case: Stem Cell Transplant Breakthrough
[ Back to News Page ] Dated: 16-Oct-2024
German Man Becomes the Seventh Global AIDS Cure Case
Stem Cell Transplant Offers New Hope for Cure
A 60-year-old German man has become at least the seventh person globally to be declared free of HIV after undergoing a stem cell transplant. Although he has been free of the virus for six years, he is only the second individual to receive stem cells that do not possess HIV-resistant genes.
Breakthrough Discovery
“I was quite surprised by this success,” said Ravindra Gupta, a microbiologist at the University of Cambridge. Gupta’s team had previously treated another person who was free of HIV. “This is a significant development.”
The first patient to clear HIV after receiving a bone marrow transplant for blood cancer was Timothy Ray Brown, known as the “Berlin Patient.” Brown and a few others received donor stem cells with a mutated CCR5 gene, through which most HIV strains enter immune cells. For many scientists, these cases indicated that CCR5 is the best target for curing HIV.
Disruptive Case
However, the latest case announced at the 25th International AIDS Conference in Munich challenges this understanding. The patient, referred to as the “Next Berlin Patient,” received stem cells from a donor with only one mutated gene copy. This means their cells express CCR5, but at lower levels than normal.
“This case clearly shows that curing HIV doesn’t have to be solely focused on CCR5,” said Sharon Lewin, an infectious disease doctor at the Peter Doherty Institute for Infection and Immunity in Melbourne, Australia.
Expanding Treatment Possibilities
This discovery expands the donor pool for stem cell transplants, as such high-risk procedures are nearly impossible for most HIV-infected individuals. About 1% of European descendants have two mutated copies of the CCR5 gene, but around 10% have only one mutated copy.
“This result broadens the boundaries for HIV treatment possibilities,” said Sara Weibel, an HIV researcher at the University of California, San Diego. Currently, there are about 40 million people living with HIV worldwide.
Long-Term Virus-Free Status
The “Next Berlin Patient” was diagnosed with HIV in 2009. In 2015, he was diagnosed with acute myeloid leukemia and subsequently underwent a stem cell transplant. Unable to find a matching donor with two mutated copies of the CCR5 gene, doctors chose a female donor with only one mutated copy. The patient underwent the stem cell transplant in 2015.
“The cancer treatment went smoothly,” said Christian Gaebler, a physician-scientist and immunologist at the Charité Medical University of Berlin. Within a month, the patient’s bone marrow cells were replaced by the donor’s stem cells. The patient stopped taking antiretroviral medication in 2018, and nearly six years later, researchers have still found no evidence of HIV replication in his body.
Successes and Challenges in Research
Previous attempts to use stem cells from donors with common CCR5 genes resulted in HIV reappearing in patients a few weeks to months after stopping antiretroviral therapy, except for one individual who successfully remained virus-free for a long time.
In 2023, HIV researcher Asier Sáez-Cirión from the Pasteur Institute reported data on a “Geneva Patient” who has not been on antiretroviral therapy for 18 months. Sáez-Cirión stated that after about 32 months, HIV has still not been detected in this patient.
Future Outlook
Researchers are exploring why these two transplants were particularly successful while others failed. They propose various mechanisms, including the impact of pre-transplant chemotherapy, the heterogeneity of donor cells, and the rapid replacement of host cells.
“The Next Berlin Patient” and his donor both had only one mutated CCR5 gene copy, which may have created more barriers for HIV to enter cells. This case provides insights for current early-stage clinical trials using gene-editing technologies such as CRISPR-Cas9 to remove the CCR5 receptor. Even if these therapies do not affect every cell, they may still have an impact.
