No active viral infection was detected in the HIV patient’s blood at the 30-month follow-up after undergoing stem cell transplantation and stopping anti-retroviral therapy, reveals The Lancet HIV journal.
Although there was no active viral infection in the patient’s body, remnants of integrated HIV-1 DNA remained in tissue samples which can be regarded as so-called ‘fossils’, as they are unlikely to be capable of reproducing the virus, suggests the researchers.
The patient who is referred to as the ‘London patient’ is the second person to attain remission from HIV after undergoing a successful stem cell transplantation from donors with mutant copies of the HIV-resistant gene CCR5Δ32/Δ32.
The patient who had suffered from Hodgkin’s lymphoma had undergone single haematopoietic stem-cell transplantation and a reduced-intensity chemotherapy drug regimen, without whole-body irradiation.
In 2019, it was reported that HIV was in remission. Ultrasensitive viral load sampling from the patient’s cerebrospinal fluid, intestinal tissue, or lymphoid tissue was collected at 29 months after interruption of ART and viral load sampling of their blood at 30 months.
Results revealed that no active viral infection was detected in samples of the patient’s blood or CSF, semen, intestinal tissue, and lymphoid tissue. The patient had a healthy CD4- CD8 cell count and the majority of their immune cells were replaced by cells derived from the HIV-resistant transplanted stem cells indicating the stem-cell transplant to be successful.
Using mathematical modelling the scientists calculated that if 80% of patient’s cells are derived from the transplant, the probability of cure is predicted at 98%; whereas if they have 90% donor-derived cells, they predict a 99% probability of cure.
The authors note that the patient will need to continue monitoring for re-emergence of the virus.
“Gene editing using the CCR5 has received a lot of attention recently. There are still many ethical and technical barriers – e.g. 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.” explains co-author on the study, Dr Dimitra Peppa, University of Oxford, UK.
Lead author of the study, Professor Ravindra Kumar Gupta, University of Cambridge, UK, cautions: “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.
The findings have been presented recently at Conference on Retroviruses and Opportunistic Infections.