Scientists may be getting closer to finding a cure for HIV after a London patient was cleared of the Aids virus.
This is welcome news to researchers and 37 million people living with HIV globally.
It is the second time a patient has ended up in remission from HIV. In 2007, another patient — identified as “the Berlin patient” — received a bone-marrow transplant from a donor with natural immunity to the virus.
American Timothy Brown, said to be the first person to “beat” HIV/Aids, was given a much more aggressive treatment, which included two transplants and total body irradiation (radiotherapy) for leukaemia.
Since then, scientists have been trying to duplicate the research with little success.
However, doctors have made a breakthrough with the London patient.
Almost three years after receiving bone marrow stem cells from a donor with a rare genetic mutation that resists HIV infection — and more than 18 months after he stopped taking antiretroviral drugs — highly sensitive tests still showed no trace of the London patient’s previous HIV infection.
“There is no virus there that we can measure. We can’t detect anything,” said Ravindra Gupta, a professor and HIV biologist from University College London who co-led a team of doctors treating the patient.
The man, who has been identified only as the “London patient”, was diagnosed with HIV in 2003 and advanced Hodgkin's lymphoma in 2012.
He had chemotherapy to treat the Hodgkin's cancer. In addition, he received implants of stem cells from a donor resistant to HIV, leading to both his cancer and HIV going into remission.
With an estimated 19.6 million people in East and Southern Africa — 1.5 million Kenyans — living with HIV and about 380,000 recorded deaths, the journey to getting a cure seems to be nearing the homestretch.
“It seems an HIV cure is possible. If we can understand better why the procedure works in some patients and not others, we will be closer to our ultimate goal of curing HIV,” said Dr Matilu Mwau, an infectious-diseases specialist at the Kenya Medical Research Institute.
He said the current treatment regime appears to have an “uncertain mechanism of action and only effective very rarely”.
Dr Mwau noted that the technology to show that HIV has been fully cleared is still under development.
“We can tell that an HIV patient is cured if we test the blood and don’t find a single virus. Currently, the machines we have can only see more than 20 viruses per millilitre. Anything lower than that reads ‘Lower than the Limit of Detection or Target not Detected," Dr Mwau explained.
He added: "HIV needs to enter a cell. If a cell lacks the entry mechanism, the virus is not able to “attach”. In the blood, the CCR5 is the most commonly used receptor by HIV-1 — the virus strain of HIV that dominates around the world — to enter cells.
“So, if the bone marrow has disabled CCR5, half of the viruses loiter “aimlessly” with intent to infect, meaning half of these viruses still have a door open for them. But a very small number of people who are resistant to HIV have two mutated copies of the CCR5 receptor. This means the virus cannot get into the cells.”
The two milestones in the search for an HIV cure have resulted from bone marrow transplants given to infected patients.
Dr Mwau cautioned that this treatment approach is not practical for healthy people with HIV, but may ultimately help find a cure.
“The bone marrow they (doctors) used had a unique feature. It had cells that are resistant to a certain kind of HIV,” Dr Mwau added.
While Prof Gupta described his patient as “functionally cured” and “in remission”, he cautioned: “It’s too early to say he’s cured.”
“By achieving remission in a second patient using a similar approach, we have shown that the Berlin patient was not an anomaly and that it really was the treatment approaches that eliminated HIV in these two people,” Prof Gupta said.
The Aids disease has killed about 35 million people worldwide since the 1980s, when it was first discovered.
Scientific research into the complex virus has led to the development of drug combinations which have been able to not only keep it at bay in most patients, but also prolong the lives of many others.
As a result, deaths have reduced drastically from 1.4 million in 2010 to 940,000 in 2017.