Two HIV patients have been found to have undetectable levels of the virus after receiving stem cell transplants as part of treatment for cancer. There has only been one other case of this kind, reported ten years ago in Berlin, Germany.
'Now we know the first case wasn't an anomaly, but is something that can be shared,' Professor Ravindra Gupta, who led the study in Nature on one of the patients while at University College London, told New Scientist.
This patient, based in the London, was diagnosed with HIV in 2003 and later diagnosed with blood cancer in 2012. He did not respond to standard cancer treatments, so the doctors and researchers switched to stem-cell therapy.
The researchers initially transplanted stem cells derived from the patient's own bone marrow, but this approach failed. The researchers then tried stem cells from a donor. These cells contained a genetic mutation that prevents the HIV virus from entering cells via a specific receptor called CCR5.
The London patient continued taking anti-HIV drugs for 16 months after the transplant. Once the HIV treatment was stopped, blood tests were taken routinely to measure levels of HIV. No HIV was detected in the man's blood for 18 months.
The third case was reported by Dr Björn-Erik Jensen, senior physician from Heinrich Heine University Hospital in Düsseldorf, Germany, at the Conference on Retroviruses and Opportunistic Infections in Seattle, Washington. The Düsseldorf patient is also a male who had HIV and was later diagnosed with blood cancer.
In 2013, this patient received stems cells from a donor containing the mutation that inhibits HIV activity through the CCR5 receptor. He was maintained on anti-HIV treatment for five and a half years following the transplant. This treatment ended in November 2018 and no HIV has been detected in his blood for three months since then.
However, researchers have noted that this form of treatment is not suitable for the vast majority of HIV patients who do not have these forms of cancer.
'The treatment [the London] patient received is not safe, and not scalable,' said Sarah Fidler, professor of HIV medicine at Imperial College London, who was not involved in the research.
Stem-cell transplants are complex procedures that carry risks of complications. Not only would this treatment pose a risk to HIV patients without cancer who respond well to anti-HIV treatment, it would also be impractical to find enough donors with the naturally occurring genetic mutation providing HIV resistance for a large-scale treatment programme, researchers have noted.
However, now when selecting suitable stem-cell donors for blood cancer patients with HIV, the genetic status of the CCR5 receptor should be considered.
'The conclusions of the study are that therapies exploiting genetic mutations of co-receptors used by HIV have the potential to cure the disease,' said Professor Áine McKnight, professor of viral pathology at Queen Mary University, London, who was also not involved in the research.