London patient cured of HIV, study claims
A case report published in The Lancet HIV has detailed the second claimed incidence of a patient cured of HIV, with no active viral infection detected 30 months after stopping antiretroviral therapy (ART). And while most HIV patients can manage the virus with current treatment options and have the possibility of living a long and healthy life, experimental research of this kind can provide insight into how a more widely applicable cure might be developed in the future.
In 2011, a patient based in Berlin (the ‘Berlin patient’) was the first person to be reported cured of HIV three and a half years after total-body irradiation, two rounds of stem cell transplantation from a donor carrying an HIV-resistant gene (a mutated form of the HIV co-receptor CCR5) and chemotherapy. The transplant aims to make the virus unable to replicate in the patient’s body by replacing the patient’s immune cells with those of the donors, whilst the body irradiation and chemotherapy targets any residual HIV virus.
The patient in this study (the ‘London patient’) meanwhile underwent one round of stem cell transplantation and a reduced-intensity chemotherapy drug regimen, without whole-body irradiation. In 2019, a study in the journal Nature reported that the patient’s HIV was in remission — this latest study provides follow-up viral load blood test results at 30 months and a modelling analysis to predict the chances of viral re-emergence.
Ultrasensitive viral load sampling from the London patient’s cerebrospinal fluid, intestinal tissue and lymphoid tissue was taken at 29 months after interruption of ART and viral load sampling of their blood at 30 months. At 29 months, CD4 cell count (indicators of immune system health and stem cell transplantation success) was measured, and the extent to which the patient’s immune cells have been replaced by those derived from the transplant.
Results showed no active viral infection was detected in samples of the patient’s blood at 30 months, or in their cerebrospinal fluid, semen, intestinal tissue and lymphoid tissue 29 months after stopping ART. The patient had a healthy CD4 cell count, suggesting they have recovered well from the transplant, with their CD4 cells replaced by cells derived from the HIV-resistant transplanted stem cells. Furthermore, 99% of the patient’s immune cells were derived from the donor’s stem cells, indicating the stem cell transplant had been successful.
Although there was no active viral infection in the patient’s body, remnants of integrated HIV-1 DNA remained in tissue samples, which were also found in the first patient to be cured of HIV. The study authors suggest that these can be regarded as so-called ‘fossils’, as they are unlikely to be capable of reproducing the virus. However, they added that the London patient will need continued, albeit infrequent, monitoring for re-emergence of the virus.
“We propose that these results represent the second ever case of a patient to be cured of HIV,” said lead author Professor Ravindra Kumar Gupta, from the University of Cambridge. “Our findings show that the success of stem cell transplantation as a cure for HIV, first reported nine years ago in the Berlin patient, can be replicated.
“It is important to note that this curative treatment is high risk, and only used as a last resort for patients with HIV who also have life-threatening haematological malignancies. Therefore, this is not a treatment that would be offered widely to patients with HIV who are on successful antiretroviral treatment.”
Study co-author Dr Dimitra Peppa, from the University of Oxford, added, “Gene editing using CCR5 has received a lot of attention recently. The London and Berlin patient are examples of using the CCR5 gene in curative therapies outside of gene editing. There are still many ethical and technical barriers — eg, gene editing, efficiency and robust safety data — to overcome before any approach using CCR5 gene editing can be considered as a scalable cure strategy for HIV.”
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