One-off 'gene jab' for all types of pain
A REVOLUTIONARY single-shot jab that delivers DNA to cells could be a new way to tackle all types of chronic pain.
The injection, which is now in clinical trials for conditions including osteoarthritis (wear and tear damage that means bones rub together), instructs cells to ramp up production of a key natural protein, IL-10, which has painkilling and anti-inflammatory properties.
Chronic pain – where the pain lasts longer than 12 weeks despite treatment – affects around one in five adults.
Despite decades of research, chronic pain is still poorly understood and hard to control.
A survey by the American Academy of Pain Medicine found that treatment with painkilling prescription drugs helps about 58 per cent of patients on average.
These drugs can also have side-effects, such as constipation, nausea and drowsiness.
With some medications, such as powerful opioids, there is also a risk of addiction.
The conventional thinking is that nerve cells called neurons are key to the pain messenger system, so most drugs target these cells.
The ineffectiveness of standard treatment has led researchers from the University of Colorado Boulder in the U.S., who are behind the new jab, to suggest that other cells called glial cells might be a cause.
These immune cells, found in the brain and spinal cord, are heavily involved in the response to illness and infections. For example, they make us ache when we're ill, and produce compounds that increase or reduce inflammation.
Usually, once an injury or illness resolves, glial cells make the IL-10 protein to dampen inflammation. (This inflammation typically causes pain because the swelling presses against nerve endings.)
But in cases of chronic pain, it's thought this mechanism somehow gets stuck and not enough anti-inflammatory IL-10 is produced.
The new injection, known as XT-150, delivers DNA in a saline solution to cells, instructing them to increase IL-10 production.
It is injected either into the fluid-filled space around the spinal cord, or, in the case of osteoarthritis, around the inflamed joint.
Because the treatment is localised and prompts the body's own anti-inflammatory and painkilling response, it does not cause the myriad side-effects associated with opioids, for instance – and the benefits can last for many months after a single injection.
‘Our IL-10 gene therapy provides the cells within, for example, the osteoarthritic joint, the recipe for making it more efficiently and effectively,' says Professor Linda Watkins, a neuroscientist who designed the jab. It is now being developed by her company, Xalud Therapeutics.
Animal studies have shown that it's highly effective, with the material remaining in joint tissue for at least six months after one jab.
A new animal study in the journal Brain, Behavior, and Immunity revealed that the drop in pain levels was three times greater after the jab when compared with a placebo.
Now six trials involving hundreds of patients with osteoarthritis are under way in the U.S. and Australia.
The company is also planning studies in back pain, peripheral nerve pain, and the pain caused by multiple sclerosis.
Commenting on the approach, Professor Sam Eldabe, a consultant in anaesthesia and pain medicine at James Cook University Hospital in Middlesbrough, North Yorkshire, said: ‘Treatment of patients with chronic inflammatory conditions remains a large unmet need.
‘If this new jab is proven to be safe and effective it would be a very exciting development in the pain world.
‘It is often administered by spinal injection, which is a complex method requiring inpatient care.'
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