A few decades ago, the idea of an HIV cure sounded unrealistic. Today, doctors describe a carefully documented case where the virus appears to be gone for good after a rare stem cell transplant. A 60-year-old man in Germany, often called the “second Berlin patient”, lived with HIV and later developed aggressive leukemia that required a high-risk transplant. After the procedure, he stopped antiretroviral therapy and has now remained HIV-free for years, with no sign of viral rebound.
Clinicians have followed his progress very closely, using repeated tests to confirm that no hidden virus remains detectable anywhere today. This case is particularly significant because the donor cells were not fully HIV-resistant, which challenges long-held assumptions about how a stem cell transplant can lead to a durable HIV cure. Researchers at Charité – Universitätsmedizin Berlin and collaborators have followed the man closely and now describe stable remission that looks indistinguishable from a cure.
A Rare Cure Doctors Did Not Expect
In earlier cure cases, donors carried two copies of a rare CCR5-Δ32 mutation that blocks HIV entry into immune cells. For this man, often called “Berlin 2” or “B2”, both he and the donor had only 1 mutated copy, so their cells still expressed some CCR5. This genetic combination still reduced CCR5 levels significantly, which limited viral entry and created better conditions for eventual remission overall. Nature’s news coverage notes that “a 60-year-old man in Germany has become at least the seventh person with HIV to be announced free of the virus after receiving a stem-cell transplant.”
Doctors monitored him for several years after stopping antiretroviral drugs and repeatedly failed to detect replication-competent virus using very sensitive tests. The European AIDS Treatment Group summarised the findings by highlighting that “a man has become the seventh person to be left HIV-free after receiving a stem cell transplant to treat blood cancer,” and that his donor cells were not fully resistant to the virus. Researchers describe this outcome as “unexpected” because earlier models suggested that partial CCR5 protection would not be enough to clear the infection.
How A Stem Cell Transplant Can Clear HIV
To understand why this case excites researchers, it helps to look at how HIV persists. According to an NIH HIVinfo fact sheet, “a latent HIV reservoir is a group of immune system cells infected with HIV but not actively producing new virus particles.” These hidden cells survive for years and reignite infection whenever treatment stops. Standard HIV medicines powerfully suppress viral replication, but they do not reach or eliminate these silent reservoirs. A stem cell transplant replaces large parts of a person’s immune system. Intense chemotherapy, sometimes combined with radiotherapy, clears many existing immune cells, including reservoir cells. When doctors infuse donor stem cells, a new immune system grows.
Reviews in Nature Medicine and other journals explain that CCR5, a surface co-receptor, is the main doorway HIV uses to enter CD4 T cells. The transplant, therefore, attacks HIV on several levels, combining physical reservoir depletion with genetic barriers and strong donor immune responses. One ScienceAlert summary of the new case notes that “the mutation essentially breaks the CCR5 ‘keyhole’ HIV attaches to, preventing the virus from entering in the first place.” Even when the donor carries only 1 mutated copy, reduced CCR5 expression may disrupt viral spread. In addition, graft-versus-leukemia and graft-versus-reservoir effects mean donor immune cells can attack any remaining cancer cells and infected host cells.
The First Patients Who Proved That An HIV Cure Was Possible
This new HIV cure sits on top of years of work. Each case built confidence slowly, as independent teams reproduced similar strategies in different hospitals and health systems worldwide. In 2007, Timothy Brown received a stem cell transplant in Berlin to treat leukemia, using donor cells with 2 CCR5-Δ32 copies. The World Health Organization recalls that “in 2007, Timothy Brown, the so-called first Berlin patient, was the first person to be considered cured of HIV.” Later, a London man named Adam Castillejo underwent a similar transplant using CCR5-Δ32/Δ32 donor cells. A Lancet HIV report led by Ravindra Gupta and colleagues concluded that their findings “represent HIV-1 cure” after years without viral rebound.
Further work, coordinated by Björn-Erik Ole Jensen and an international team, described the “Düsseldorf patient”. In a Nature Medicine brief communication, the authors wrote that “four years after analytical treatment interruption, the absence of a viral rebound is strong evidence for HIV-1 cure after CCR5Δ32/32 HSCT.” The Düsseldorf patient’s care team at the University Hospital Düsseldorf and partner institutions monitored him for almost 10 years after his transplant. A summary from the University of the Witwatersrand states that the “Düsseldorf patient” became “the third person in the world to be completely cured of the HI virus by a stem cell transplant.” These early cases convinced scientists that an HIV cure is biologically possible, at least in extremely specific clinical situations.
Geneva Patient And A Cure Without Genetic Protection
For years, every confirmed HIV cure after a stem cell transplant involved donor cells with the CCR5-Δ32 mutation. This surprising result broadened scientific thinking about which biological pathways might support durable remission when CCR5 disruption is absent entirely. That changed with the Geneva patient, whose case appeared in Nature Medicine in 2024. In this man, the donor had standard or “wild-type” CCR5, so his cells remained fully susceptible to HIV. A press release from Institut Pasteur explains that “a total of seven individuals worldwide (two patients in Berlin and patients in London, Düsseldorf, New York, City of Hope, and Geneva) are considered likely to have been cured or to be in long-term remission of HIV infection after receiving a bone marrow transplant to treat blood cancer.”
Among these, “Romuald, the Geneva patient, who is being monitored at Geneva University Hospitals, is the only one to have experienced HIV remission following a bone marrow transplant without the CCR5-delta 32 mutation.” The Geneva study, coordinated by Professor Alexandra Calmy at the University of Geneva and Professor Asier Sáez-Cirión at Institut Pasteur, showed a gradual decline in the viral reservoir after transplantation. Researchers eventually stopped treatment and still could not detect replication-competent virus. They propose that strong graft-versus-host reactions and powerful innate immune responses may have removed infected cells so effectively that the usual CCR5 protection was not required.
What Makes The Second Berlin Patient Different
The newly highlighted case of the second Berlin patient combines features from earlier stories. Here, both patient and donor carried 1 CCR5-Δ32 copy. Clinicians see him as a bridge between mutation-heavy cures and cases that rely mainly on immune-mediated clearance across different settings. The cells, therefore, expressed CCR5 at lower levels, yet not enough to guarantee full resistance. Gaebler and colleagues presented the core findings at the International AIDS Conference, describing long-term HIV remission more than 6 years after transplant.
Nature’s news piece summarises the situation clearly: the man “has become at least the seventh person with HIV to be announced free of the virus after receiving a stem-cell transplant,” and he is “only the second person to receive stem cells that are not resistant to the virus.” A separate explainer notes that “the case suggests that double copies of CCR5 Δ32 are not a requirement for durable HIV remission after stem cell treatment.” Scientists writing in a recent review on stem cell therapies for HIV cure argue that this group of patients demonstrates the value of combining deep reservoir reduction with genetic or immunologic barriers to reinfection. The B2 case helps expand the menu of possible donor types and suggests that partial CCR5 protection, combined with strong graft-versus-reservoir effects, might still deliver a true HIV cure.
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How Doctors Decide When To Use The Word “Cure”
Clinicians use the term “cure” with great caution. They work with strict definitions, since premature announcements could mislead patients and damage trust in ongoing HIV research and care. HIV normally returns quickly when treatment stops because latent reservoir cells begin producing virus again. NIH explains that reservoir cells “are not actively producing new virus particles,” which makes them invisible to standard drugs and immune responses. Researchers, therefore, ask 2 key questions. First, does the virus stay undetectable for many years after stopping all HIV medicines, even when they use extremely sensitive tests on blood and tissue samples?
Second, do the person’s HIV-specific immune responses fade over time, suggesting the immune system no longer “sees” viral antigens? In the Düsseldorf case, Nature Medicine authors wrote that “the absence of a viral rebound is strong evidence for HIV-1 cure after CCR5Δ32/Δ32 HSCT.” For the Düsseldorf man, an NCBI news summary noted “there is ‘strong evidence’ that the man in Düsseldorf, Germany, was cured through a high-risk procedure that offers hope for further research.” For the Geneva and Berlin 2 patients, teams in Geneva, Paris, and Berlin applied similar criteria, combining negative outgrowth assays, vanishing reservoir signals, and years of drug-free remission. When those boxes stay ticked over long follow-up periods, experts start to speak of an HIV cure rather than simple suppression.
Why Stem Cell Transplants Are Not A Scalable HIV Cure
Despite the excitement, stem cell transplants will not become routine HIV cure treatments. Clinicians reserve them for situations where cancer directly threatens life and conventional therapies no longer offer a realistic chance. These procedures treat life-threatening blood cancers, not uncomplicated HIV infection. They involve intense chemotherapy, possible radiotherapy, and a period of profound immune suppression, which raises the risk of severe infection and death. Reviews of published transplant-based remission cases describe the procedure as a high-risk option that mainly supports further research, not a practical population level solution.
Nature’s coverage underscores this point and states that CCR5-Δ32 stem cell strategies will probably never become standard HIV treatment. Most people living with HIV do very well on daily or long-acting antiretroviral therapy, which carries far less risk than an allogeneic stem cell transplant. Global guidelines still recommend antiretroviral therapy for almost everyone, while researchers restrict transplant-based approaches to carefully selected individuals with severe cancers. At the same time, these cure cases give researchers a powerful proof of concept. They show that scientists might eventually deliver a broader HIV cure if they reproduce reservoir clearance, strengthen immune control and avoid the need for a full transplant.
What This Case Means For Future HIV Cure Research
The second Berlin patient’s cure arrives alongside other promising strategies. A small study led by Steven Deeks at the University of California, San Francisco, combined therapeutic vaccines, broadly neutralising antibodies, and an immune-activating drug. One participant maintained viral control for more than 18 months after stopping therapy. Although this result does not match the permanence of a stem cell transplant cure, it shows that complex immunotherapy can move the needle toward drug-free remission. Researchers at Institut Pasteur and their partners argue that these transplant cases highlight “promising avenues for research aimed at achieving remission for HIV infection,” even in people who never receive donor cells. A Nature News analysis adds that the growing list of cured or long-term remission patients “suggested that CCR5 was the best target for an HIV cure,” while the newer Geneva and Berlin 2 data show that alternative mechanisms also matter.
One recent review in Current Opinion in HIV and AIDS, led by Javier Martínez-Picado, stresses that these “power of ten” remission cases can guide combination approaches that mix gene editing, targeted antibodies, latency-reversing agents, and immune-based therapies. As one ScienceAlert summary of the latest transplant cure notes, “this underscores the critical importance of modulating and potentially eliminating the HIV reservoir in strategies aimed at long-term remission and cure.” For now, the new stem cell transplant case offers hope, but not a template for mass treatment. It tells people living with HIV that scientists can already cure a small number of patients in specific circumstances. It also gives researchers concrete biological clues they can build into safer, more scalable interventions that might one day deliver a widely accessible HIV cure.
Disclaimer: This article was created with AI assistance and edited by a human for accuracy and clarity.
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