Gene Control, Delivered Directly to the Brain

Technology Review – A biotech company called Alnylam announced today that a small clinical trial for a genetic therapy based on RNA interference, or RNAi, suggests that the technique can have a powerful effect on its target gene. The therapeutic effect lasted for over a month with just one dose. The company is also working with a medical device maker, Medtronic, on a way to deliver RNAi treatment directly to the brain, in order to treat the degenerative brain disease Huntington’s.

The patients in the trial have a genetic disorder that originates in the liver and leads to the buildup of protein deposits in many organs. Alnylam, a Cambridge, Massachusetts-based company, says its RNAi therapeutic, given at its highest dose, reduces the amount of the faulty protein that spurs the disease by almost 94 percent.

The positive results add weight to the notion that RNAi therapeutics could eventually help patients with a range of genetic diseases. RNAi therapy involves researchers producing snippets of RNA, a close relative of DNA, that match a portion of a gene of interest. When administered, this so-called small interfering RNA (siRNA) causes the destruction of that gene’s products before it can be turned into a protein.

Huntington’s, for which there is no cure, is caused by the loss of neurons due to a toxic protein made by a tainted gene. The idea behind the new treatment is to stop at least some of that protein’s production so that it cannot damage the brain.

The treatment would use a device made by Medtronic that is already implanted in more than 250,000 patients to treat chronic pain and spasticity. The device features a catheter connected to a drug pump that’s surgically implanted into the abdomen. The pump pushes drugs through the device and into the fluid around the spinal cord. In the case of the Huntington’s RNAi work, the system is adapted to deliver liquids directly into the brain tissue.

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