New gene therapy treatment raises hope for HIV cure

Posted Mar 7, 2014 by Tim Sandle
A new gene therapy designed to combat HIV using genetically modified cells has been trialed and the initial results are promising following the first human clinical trial.
In analysing DNA barcodes across 100 000 species  researchers found a telltale sign showing that alm...
In analysing DNA barcodes across 100,000 species, researchers found a telltale sign showing that almost all the animals emerged about the same time as humans
The gene therapy treatment used modified cells that are resistant to the virus to shield patients from HIV. According to the BBC, once transferred into the human body the genetically modified genes raised patients' defenses against HIV by replacing some of their natural immune cells with the gene therapy versions.
Gene therapy is the use of DNA as a drug to treat disease by delivering therapeutic DNA into a patient's cells. The most common form of gene therapy involves using DNA that encodes a functional, therapeutic gene to replace a mutated gene.
The basis of the gene therapy came from previous research which had looked at why a small proportion of the population are naturally resistant to HIV. Tracing this to a specific mutation it has been found that a small number of people lack a protein called CCR5-delta-32 in their T-cells (these are white blood cells that are vital to human immune responses). The absence of this protein means that HIV cannot latch onto the outer protein of the body's cells. By being unable to attach, HIV is then unable to enter the cells, infect them and then multiply.
To develop the gene therapy scientists collected white blood cells from the HIV patients selected for the trial. The researchers next used a procedure called gene editing to modify the cells, so that they carried the rare mutation — the absence of the CCR5 protein — that makes people resistant to HIV. Once this was complete they multiplied the modified cells and infused a batch of 10 billion back into each patient in the test group (although only around 20 percent were successfully modified). The research group have named the therapy "Sangamo BioSciences therapy" (SB-728-T).
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For the clinical trial a group of volunteer patients were divided into two groups. Half of the participants continued with their standard treatment (the control group); whilst the other half were taken off their usual drugs for three months and given the gene therapy treatment (the test group). With the group given the gene therapy, scientists recorded reduced levels of the virus (whereas the control group showed no change). Based on this outcome, of a measurable reduced viral load, the treatment has been declared a success by the science team behind the study. Remarkably, in one patient, the virus could "no longer be detected at all," according to a Massachusetts Institute of Technology (MIT) report.
To run the study, which began in 2009, the science team gained permission from the U.S. Food and Drug Administration (FDA) and the Recombinant DNA Advisory Committee of the U.S. National Institutes of Health.
The two lead scientists, Bruce Levine and Carl June, from the University of Pennsylvania, to The Guardian "We are absolutely encouraged by these results. This is potentially a new therapy for HIV."
The potential of the new treatment is that a small dose modified immune cells could become an alternative for HIV patients who currently face spending the rest of their lives on anti-retroviral drugs. However, such a treatment would be expensive, so any benefit would depend on how long people could be freed from drugs and how long that protection would last for.
The science team are, at this stage, cautious not to draw strong conclusions from what was a small scale trial; nonetheless, the results are encouraging and the suppression of the HIV virus exceeded expectations. Further trials will be required to see if the results are reproducible and to ascertain if the technique is safe and effective.
Bruce Levine outlined this potential by explaining "People diagnosed in their 20s are on anti-retroviral therapy for the rest of their lives. There are side effects. People miss days. And there is drug-resistance. This is a continuing problem." As to whether the gene therapy process could lead to a cure for HIV, Levin was cautious: "Cure is a four letter word. We don't like to use it, particularly with HIV. We are looking at improving the health and immune function of people with HIV."
Wired notes that other academics have cautiously welcomed the findings. For example, researchers from Stanford and Harvard Universities, Mark Kay and Bruce Walker, have commented: "The tantalizing question... is whether it might actually have been partially effective. A definitive answer to this question will require additional studies."
The results of the study have been published in the science journal New England Journal of Medicine. The research paper is titled "Gene Editing of CCR5 in Autologous CD4 T Cells of Persons Infected with HIV."