A patient from London became the second ever person to experience remission from HIV-1 after stem cell transplantation, reports a paper led by researchers at University College London (UCL) and Imperial College London. The patient has been experiencing remission for the past 18 months after ceasing anti-retroviral therapy.
The research which has been carried out with partners at the University of Cambridge and the University of Oxford has been published in Nature.
The first such case was reported ten years ago. The patient who became known as the ‘Berlin Patient’ has been the first person to achieve remission. Both the patients were treated with stem cell transplants from donors carrying a genetic mutation that prevents expression of an HIV receptor CCR5.
“At the moment the only way to treat HIV is with medications that suppress the virus, which people need to take for their entire lives, posing a particular challenge in developing countries,” said the study’s lead author, Professor Ravindra Gupta (UCL Infection & Immunity, UCLH and University of Cambridge) in a press statement.
“Finding a way to eliminate the virus entirely is an urgent global priority, but is particularly difficult because the virus integrates into the white blood cells of its host”, he said.
CCR5 is the most commonly used receptor by HIV-1.People who have two mutated copies of the CCR5 allele are resistant to the HIV-1 virus strain that uses this receptor, as the virus cannot enter host cells.
The London patient was diagnosed with HIV infection in 2003 and was on anti-retroviral therapy (ARV) since 2012. Later that year, he was diagnosed with advanced Hodgkin’s lymphoma. In addition to chemotherapy, he underwent a haematopoietic stem cell transplant from a donor with two copies of the CCR5 Δ32 allele in 2016.
The patient remained on ARV for 16 months after the transplant, at which point the clinical team and the patient decided to interrupt the therapy to test if the patient was truly in HIV-1 remission.
Remission is achieved when HIV RNA becomes undetectable in blood.
Regular testing confirmed that the patient’s viral load remained undetectable, and he has been in remission as the immune cells remained unable to express the CCR5 receptor.
The first, Berlin Patient, also received a stem cell transplant from a donor with two CCR5 Δ32 alleles, but to treat leukaemia. But he was given two transplants, and underwent total body irradiation, while the UK patient received just one transplant and less intensive chemotherapy.
Both patients were reported to have experienced mild graft-versus-host disease.
One of the major challenge to the treatment is in finding donors who carried two copies of the mutant co-receptor.
“Only about 1% of Europeans carry two copies of mutant CCR5. I am not sure about Indians but it is not present in Africans. But we can use gene editing approaches to delete CCR5,” said professor Gupta.
“While it is too early to say with certainty that our patient is now cured of HIV, and doctors will continue to monitor his condition, the apparent success of haematopoietic stem cell transplantation offers hope in the search for a long-awaited cure for HIV/AIDS,” said professor Eduardo Olavarria (Imperial College Healthcare NHS Trust and Imperial College London) in a report published by UCL.