HIV Cure: Gene Therapy on CCR5 Receptor Showed Positive Result; One Patient Reached Undetectable Viral Levels

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By Ryan Inoyori | March 10, 2014 5:41 PM EST

Scientists are now studying the possibility of replicating a genetic mutation on human T-cells to help fight HIV infection. It replicates the known genetic factor called CCR5 delta 32 that prevents HIV to attach itself with immune cells and render it unable to replicate in the body.

Engineering Immune Cells

Sangamo Biosciences conducted an experimental gene modifying strategy to control HIV effectively without ever needing any antiretroviral drugs or ART. In a small study performed on humans, researchers reported the engineering of a rare genetic mutation that is found to only 1 per cent of the world's population which protects carriers from becoming infected by the virus.

Some patients in their study received genetic modification treatment to resist HIV. They reported that some patients showed positive results by having decreased viral load during a temporary halt of antiretroviral drug treatment with surprising patient who reached undetectable viral levels in his blood.

"Sangamo's HIV suppression is promising but very early and far from a cure. This is very early study for technology and safety validation," Michael Yee analyst at RBC Capital Markets said according to Reuters.

Replicating CCR5 Delta 32

Sangamo Biosciences used a technique which disrupts a gene factor found in immune cells called CCR5 that is being used by HIV to attach itself, infect and replicate on T-cells. Altering CCR5 receptor will help disable the virus' ability to use T-cells to infect humans.

Each participant had their immune cells harvested from the blood, then researchers applied zinc-finger nucleases to edit genomes. Zinc finger nuclease breaks the copies of CCR5 gene, then infused back to the patient. However, performing such engineering isn't perfect as they cannot get every immune cell disrupted.

"About 25 per cent of the cells have at least one of the CCR5 genes interrupted," according to the CEO of Sangamo Biosciences, Edward Lanphier.

Rejection isn't a problem with this procedure since all cells came from the patient's but modified to resist HIV compared to regular immune cells.

Study notes include:

1. One week after infusion resulted in detectable modified T-cells in patients' blood.

2. Four weeks after infusion, six out of 12 patients had their ART stopped.

3. Four among six of those patients showed HIV levels dropped.

4. One patient's viral load reached undetectable levels in the blood.

5. Best responder is someone who had naturally mutated copy of CCR5 delta.

Individuals carrying disrupted CCR5 gene in their immune cells have slower progression to AIDS compared to infected patients with the undisrupted CCR5 gene. These immune cells with disrupted CCR5 gene becomes resistant against HIV and enables them to fight back infection.

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