Bone marrow transplant sparks long-term remission in second HIV patient, renewing hope for a cure
The cautiously optimistic call it sustained remission, others are hopeful it is a cure — but the doctors are impressed. An unnamed patient in London, once afflicted with cancer and the virus that causes AIDS, is free of both, courtesy an immune system overhaul triggered by a bone marrow transplant from an HIV-resistant donor.
The case comes a dozen years or so after the “Berlin patient” — now identified as Timothy Ray Brown — who achieved sustained remission following the same procedure for his leukemia. Although Brown underwent two transplants, was given total body irradiation no longer in use today, and was placed in an induced coma, he eventually recovered and was deemed HIV-free. Scientists took note, and tried repeatedly to duplicate the feat, but in vain.
On Tuesday researchers from University College London and Imperial College London, together with teams at the University of Cambridge and the University of Oxford, reported the second known case of sustained remission — in an individual who asked to retain his anonymity and is accordingly just referred to as the “London patient”.
Both Brown and the London patient received donations from donors with two copies of the allele that prevents the expression of CCR5, a gene commonly used by HIV as a back door into a cell. The trait is naturally common in parts of Northern Europe and confers the ability to resist an HIV infection from the AIDS virus. It is this trait that rogue Chinese scientist Jiankui He attempted to confer via gene editing in his widely condemned CRISPR experiment earlier this year that culminated in the birth of two genetically modified twin baby girls.
The London patient was diagnosed with an HIV infection in 2003, and in 2012 he began taking antiretroviral (ARV) therapy. Later that year, it was confirmed he had advanced Hodgkin’s Lymphoma. On top of chemotherapy, he underwent the stem cell transplant in 2016. The surgery was relatively uncomplicated, but not without side effects, including mild graft-versus-host disease.
Chemotherapy can be used to thwart HIV as it snuffs out cells that are dividing – and the researchers suggest that replacing immune cells devoid of the CCR5 receptor appears to be the crucial ingredient precluding HIV from making a comeback.
Following the transplant, for 16 months the London patient was given ARV therapy, after which his treatment was interrupted to evaluate whether he was truly in HIV remission. Regular and sensitive testing has confirmed that the patient has indeed remained in remission 18 months since ARV therapy was ceased.
“We need to understand if we could knock out this receptor in people with HIV, which may be possible with gene therapy,” said lead author of the study Ravindra Gupta, in a statement.
Gupta was at UCL when the study — to be published in the journal Nature on Tuesday — was conducted; he has since moved to the University of Cambridge.
“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,” added Professor Eduardo Olavarria from Imperial College London.
According to the WHO, there are nearly 37 million people globally living with HIV — of which roughly 60% are on ARV, as of 2017. Once a death sentence, the virus that causes AIDS is typically suppressed using ARV therapy and is now upgraded to the position of a chronic disease.