One More HIV Cure Case Reported After Sibling Stem Cell Transplant

In a significant development for HIV research, a patient in Oslo has achieved sustained remission of HIV following a stem cell transplant from a genetically resistant sibling donor. This case, reported in early 2024, adds to a growing body of evidence suggesting that curative strategies for HIV may be possible through targeted hematopoietic stem cell transplantation (HSCT) in individuals with specific genetic traits.

Understanding the Oslo Patient Case

The so-called “Oslo patient” is a man living with HIV who underwent a stem cell transplant to treat an underlying hematologic malignancy. His donor was his biological brother, who carried a rare homozygous mutation in the CCR5 gene — specifically, the CCR5-Δ32 delta 32 mutation. This genetic variant prevents the expression of the CCR5 co-receptor on CD4+ T cells, which HIV uses to enter and infect immune cells. Individuals with two copies of this mutation are naturally resistant to most strains of HIV-1.

Following the transplant, the patient discontinued antiretroviral therapy (ART) under close medical supervision. As of the latest follow-up, more than 14 months after stopping ART, no detectable HIV RNA or proviral DNA has been found in blood or tissue samples using highly sensitive assays. The patient remains in clinical remission with no signs of viral rebound.

How CCR5 Resistance Blocks HIV Infection

HIV primarily infects CD4+ T cells by binding to the CD4 receptor and then co-receptors CCR5 or CXCR4. The CCR5-Δ32 mutation results in a non-functional CCR5 protein, blocking viral entry for strains that rely on this co-receptor — which include the majority of transmitted HIV viruses. People who inherit two copies of the mutated gene (one from each parent) do not express functional CCR5 on their immune cells and are highly resistant to HIV infection.

This natural resistance inspired the approach used in the Berlin, London, and now Oslo cases: replacing a patient’s vulnerable immune system with one derived from donor stem cells that lack CCR5 expression.

Context: Previous HIV Cure Cases

The Oslo case is not the first instance of HIV remission following stem cell transplantation. To date, there have been a few well-documented cases:

• The Berlin Patient (Timothy Ray Brown): The first person considered cured of HIV after receiving two stem cell transplants from a CCR5-Δ32 homozygous donor to treat acute myeloid leukemia. He remained off ART and free of detectable virus until his death in 2020 from recurrent leukemia.
• The London Patient: Achieved sustained remission after a stem cell transplant for Hodgkin’s lymphoma from a CCR5-Δ32 donor. Has remained in remission off ART since 2019.
• The Düsseldorf Patient: Also received a CCR5-Δ32 stem cell transplant and has been in remission off ART for over four years as of 2023.

What distinguishes the Oslo case is that it is the first reported instance where the donor was a sibling with the protective genetic trait, highlighting the potential for familial screening to identify suitable donors within families.

Limitations and Challenges of This Approach

Whereas promising, stem cell transplantation for HIV cure remains highly limited and is not a scalable solution for the global HIV epidemic. Key constraints include:

• High Risk: Allogeneic stem cell transplantation carries significant risks, including graft-versus-host disease (GVHD), infections, and transplant-related mortality. It is only justified in patients with life-threatening conditions requiring the procedure, such as certain cancers.
• Donor Rarity: The CCR5-Δ32 homozygous genotype is uncommon, occurring in about 1% of people of Northern European descent and much less frequently in other populations. Finding matched donors with this trait is challenging.
• Not Universally Effective: Some HIV strains utilize the CXCR4 co-receptor instead of CCR5. Individuals whose virus relies on CXCR4 would not benefit from CCR5-deficient transplants.
• Requires ART Interruption Under Supervision: Any attempt to stop ART must be done in a controlled clinical setting with frequent monitoring to detect viral rebound early.

Because of these risks, this approach is not considered a viable cure strategy for most people living with HIV. Instead, it serves as a proof of concept that eradication of HIV is possible under specific conditions.

Implications for Future HIV Cure Research

Each successful case deepens scientific understanding of HIV persistence and reservoirs, informing the development of safer, more broadly applicable curative strategies. Current research focuses on:

• Gene editing techniques like CRISPR to disrupt CCR5 in a patient’s own stem cells.
• Therapeutic vaccines and broadly neutralizing antibodies to enhance immune control.
• “Kick and kill” strategies to reactivate latent virus and eliminate infected cells.
• Cell and gene therapies aimed at creating HIV-resistant immune systems without requiring full transplantation.

The Oslo case reinforces the importance of the CCR5 pathway as a valid target and supports continued investment in gene-based approaches that mimic the natural protection seen in CCR5-Δ32 individuals.

Conclusion

The reported remission of HIV in the Oslo patient following a sibling stem cell transplant marks another milestone in HIV cure research. While this method remains limited to exceptional circumstances due to its risks and donor requirements, it provides compelling evidence that HIV can be eradicated from the body. As science advances, the insights gained from these rare cases may pave the way for safer, more accessible cures that could one day benefit the millions of people living with HIV worldwide.

This article is based on verified medical reports and peer-reviewed understanding of HIV pathogenesis and stem cell transplantation. It does not constitute medical advice. Individuals should consult their healthcare providers regarding treatment decisions.