German Man Achieves Long-Term HIV Remission After Stem Cell Transplant
A German man has achieved an incredible feat by remaining in remission from HIV for six years after receiving a stem cell transplant to treat leukemia. Known as Berlin 2 (B2), he is the seventh known HIV patient to achieve long-term remission.
B2 received donor stem cells with only one copy of a mutated gene that confers resistance to HIV, unlike the usual two copies given to other patients. This single-copy mutation was thought to provide temporary resistance, raising questions about how it led to the clearance of the virus from his system.
The breakthrough, led by immunologist Christian Gaebler of Charité – Universitätsmedizin Berlin, offers a new pathway to understanding potential HIV cures. HIV is a challenging virus to treat due to its rapid mutation and ability to develop drug resistance.
HIV targets the body’s immune cells and can remain dormant in a latent reservoir, making it difficult to eradicate. Stem cell transplants have shown success in depleting these reservoirs by rebuilding the immune system to recognize and eliminate hidden virus copies.
While previous cases of HIV remission involved donors with double copies of a rare mutation called CCR5 Δ32, B2 only had one inherited copy of this mutation. Despite this, he achieved remission after a full stem cell transplant in 2015.
Since stopping antiretroviral therapy in 2018, B2’s virus levels have remained undetectable, indicating a potential cure. This case challenges the notion that double copies of CCR5 Δ32 are necessary for durable HIV remission.
Other patients, like one from Geneva, have also achieved remission without the CCR5 Δ32 mutation, showing the potential for alternative pathways to HIV cure. Further research is needed to understand why some patients experience viral rebound after stem cell transplants.
While the CCR5 Δ32 stem cell procedure is not a standard HIV treatment due to its risks, it provides valuable insights for developing pharmaceutical and gene editing treatments. The focus is shifting towards reducing reservoirs and enhancing immune responses for long-term remission and cure.
The researchers emphasize the importance of modulating the HIV reservoir for achieving a cure. The results of this groundbreaking case have been published in Nature.
