Cerylid to test new clot-prevention drug

Heart surgeons who perform coronary bypass operations or aorta grafts face a dilemma: they need to use anti-clotting agents to prevent potentially lethal post-surgical clots, but standard blood-thinning drugs like aspirin can cause bleeding from graft joins - or from weakened blood vessels in the brain.

Melbourne meditech Cerylid Biosciences, believes it has a potential solution: a new class of small-molecule drugs that selectively suppress pathological blood-clotting, which can cause stroke, without affecting the natural clotting process that seals and patches leaking blood vessels.

Monash University researcher Assoc Prof Shaun Jackson, headed the research team at The Australian Centre for Blood Diseases that discovered the new class of clot-blocker drugs.

Jackson's research group at the Alfred Hospital in Prahran, discovered the novel drugs by chance several years ago, while investigating how the pathological and normal clotting processes differ.

Post-surgical clots are an unavoidable hazard to heart-surgery patients. They can be caused by debris released from the walls of diseased blood vessels during surgery, or can arise from fluid-shear forces generated by turbulent blood flow at points where blood vessels have been rejoined, or differ in diameter.

Once initiated, the clots can completely block major blood vessels, or may detach and be carried into the brain, where they can block blood supply to areas of the brain, causing a stroke.

"The two processes [natural vs pathological blood clotting] are quite distinct," Jackson said. "We identified a key mechanism that distinguishes them, and then found a class of molecules that only inhibit pathological clotting."

Stroke, and heart attacks due to blocked coronary arteries, are the leading cause of death and disability in western nations, and cause the deaths of some 50,000 Australians every year.

The potent anti-clotting agent, tissue plasminogen activator (TPA) prevents or breaks down pathological clots by blocking synthesis of fibrin, the 'mortar' that binds activated platelet cells together to form clots.

Warfarin and aspirin prevent clotting by suppressing platelet activation, but both carry a risk of uncontrollable bleeding. Aspirin, which is effective in only one in four cases, can also damage the lining of the stomach, causing bleeding and gastric ulcers.

Cerylid, which acquired the IP for the new drugs when it merged with former owner Kinacia last year, ran a pre-clinical trial of a first-generation clot-inhibitor in 2002. It could only be administered intravenously.

Cerylid CEO Dr Gregg Smith, said today the new molecule, CBL 1309, was developed both for intravenous and oral administration. The company plans to take it into clinical trials in human volunteers in September, and begin phase 2 trials in 2006.

"If it makes it to market, it could be a blockbuster drug," Smith said. The anti-platelet marked is currently worth billions. CBL 1309 would be a direct competitor for the market-leading clotbuster Plavix, which sells around US$2 billion a year.

Monash University researchers developed CBL 1309 in collaboration with teams at Melbourne University's Department of Pharmacology, and University College, London.