Although there is no definitive cure for the disease, there have been many advances in treatment that have made it possible for patients to live longer lives.
Last year, the US Centers for Disease Control and Prevention declared that people who religiously take their HIV medication for six months can reach a point where their virus is not transmittable.
However, experts say gene editing — which has been recently approved by the FDA to treat cancer and a rare form of childhood blindness — has been developed to such an extent that it could be viewed as the best answer for a cure.
Matt Chappell, an HIV patient, participated in a gene therapy experiment where scientists removed some of his blood cells and disabled a gene to help them resist HIV. Pictured: Matt Chappell, right, is checked by his doctorl during an appointment in January 2018
Gene therapy can make cells more resistant to HIV
Matt Chappell, of San Francisco, California, has been taking the strongest AIDS drugs for more than a decade, but they weren’t able to full control his HIV infection.
He then participated in a gene therapy experiment in 2014 where scientists removed some of his blood cells, disabled a gene to help them resist HIV, and returned these ‘edited’ cells to him.
So far, it has given Chappell the next best thing to a cure.
‘I’ve been off medications for three and a half years,’ he said. He even was able to keep the virus in check despite cancer treatments last year that taxed his immune system.
Chappell was lucky, though. Only a few of the 100 others in those experiments were able to stay off HIV drugs for a couple years; the rest still need medicines to keep HIV suppressed.
Now researchers think they can improve the treatment and are trying again to tackle HIV by doctoring DNA. New studies to test these tweaked approaches in people are getting underway.
‘Gene therapy techniques have advanced greatly,’ said Dr Otto Yang of the UCLA AIDS Institute, one place working on this. ‘A lot of people are thinking it’s the right time to go back.’
They include Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which is funding some of the new studies.
Although Dr Fauci doesn’t think the technique will become common because millions of people do well on existing treatments, he says it could help those who can’t easily control the virus, and should be pursued because it holds potential for a cure.
‘They’re very bold, innovative techniques, mostly to try and cure people,’ he said. ‘It’s worth trying because the science is there.’
More and more experts are turning to gene-editing to prevent HIV.
A 2016 study published in the Scientific Report revealed researchers at Temple University developed a gene editing method that detects HIV DNA in people’s T cell genome, the DNA set of a type of white blood cells.
Once the DNA is edited out, the loose ends of the genome that were once attached to the HIV infection are reunited by the cell’s own DNA repair system.
Not only is the cell HIV-free, but it’s also protected from a new infection.
Timothy Brown’s cure gave hope
So far, Timothy Brown is the one of only two people in history to have been cured of HIV.
He had a bone marrow transplant more than a decade ago to cure his leukemia, and the stem cells came from a donor with natural immunity to HIV.
The donor lacked a common gene that makes an entryway HIV uses to infect T cells.
This transplant, which replaces a sick person’s immune system with stem cells from the bone marrow of a healthy person, gave Brown that protection, but procedures like that are too risky and impractical for wide use.
In fact, attempts to replicate Brown’s procedure has been deadly.
A report published by the New England Journal of Medicine in 2014 described six attempts to treat HIV patients with a stem cell donation, but none lived longer than a year.
Scientists have been trying to find a way to create similar immunity by altering some of a patient’s own cells. They use a gene editing tool called zinc finger nucleases, which cut DNA at a precise spot to disable the HIV entryway gene.
The California company that makes the editing tool, Sangamo Therapeutics, sponsored the initial studies.
‘It worked, the T cells were edited,’ said Sangamo’s president, Dr. Sandy Macrae. But it didn’t work quite well enough: the altered T cells were outnumbered by T cells that were not altered and could still be infected.
Now, Dr John Zaia at City of Hope, a research center in Duarte, California, is trying the approach with a twist. He’s using blood stem cells — parent cells that produce many others.
Once a stem cell is altered the benefit should multiply and last longer, Zaia said.
Researchers were able to get rid of dormant HIV-infected cells
What is gene editing?
Gene editing is a type of genetic engineering where DNA is inserted, deleted or modified to treat – and perhaps some day prevent – diseases.
The FDA approved the method to treat blood cancer and a rare form of childhood blindness.
In 2014, scientists removed blood cells from Matt Chappell, a man who’s HIV-positive, disabled a gene to help them resist HIV, and returned the edited cells to him.
Chappell has been off medication for three and a half years since his genes have been edited.
Last year, researchers at Oregon Health and Science University successfully modified human embryos that had a genetic mutation responsible for an often fatal hereditary heart condition.
However, a 2017 study published in Molecular Therapy was able to remove the virus in animals.
Scientists at the Lewis Katz School of Medicine at Temple University (LKSOM) and the University of Pittsburgh were able to remove HIV DNA from three different animal models, including a mouse that was transplanted with a ‘humanized’ immune system.
‘We also show that the strategy is effective in two additional mouse models, one representing acute infection in mouse cells and the other representing chronic, or latent, infection in human cells.’ said Dr Wenhui Hu, associate professor in the Center for Metabolic Disease Research and the Department of Pathology.
The fact that researchers were able to get rid of dormant or latent forms of the virus is a breakthrough.
The latent form of the HIV means cells that are infected with the virus have stopped producing new HIV cells.
According to AIDS Info, HIV medicine — which prevents the virus from multiplying — has no effect on groups of infected cells that aren’t actively producing HIV, or latent reservoirs.
This makes it hard for people to completely get rid of the virus.
According to experts at AIDS Info, targeting and destroying latent reservoirs is one of the major challenges facing HIV researchers.
Experts say gene therapy could be a long-term solution for HIV
University of Pennsylvania scientists are trying a two-part approach: besides knocking out the gene for the HIV entryway, they’re adding a gene to help T cells recognize and kill HIV.
This second part is called CAR-T therapy, a treatment approved last year for treating cancer.
The new study’s leader, scientist James Riley, is encouraged that some patients at Penn who were in the early studies kept HIV suppressed for nearly a year without drugs.
‘You’d never know they were sick’ even though the virus could still be detected, Riley said. ‘At some point you’re going to have confidence that it’s not going to come back.’
Chappell’s doctor, Christopher Schiessl at One Medical, a health clinic in San Francisco, hopes that’s the case for Chappell. Although he’s doing well now, Chappell is showing signs that his immune system may be weakening, Schiessl said.
Chappell is optimistic, and believes gene therapy ultimately will provide a long-term solution.
‘If we’re going to cure HIV,’ he said, ‘this is how it’s going to happen.’