Melbourne firm develops JAK kinase inhibitor

A new JAK kinase inhibitor developed by Melbourne biotech Cytopia had far higher activity than blockbuster drug Glivec in tests on cells from a patient with chronic myeloid leukaemia, the company announced today.

The inhibitor acts by a different mechanism to Glivec, suggesting that it could be used in patients whose tumours had developed resistance to Glivec via a mutation in the drug binding site, said Dr Kevin Healey, the CEO of Cytopia, which is 79 per cent owned by biotech investment group Medica Holdings (ASX: MCA).

"It's dramatically more potent than Glivec," Healey said. A side-by-side comparison suggested that the new inhibitor had as much as 60-fold higher activity. In vivo animal studies have also been "highly encouraging" he said.

Cytopia's chief scientific officer Dr Andrew Wilks said that an animal model had been developed for a rare form of leukaemia, and used to test the activity of the new inhibitor.

"In this model we usually see prolific growth of leukemic cells in the spleen and lymph nodes. Treatment with our lead molecule completely eliminated this growth in a period of only two weeks," Wilks said.

The inhibitor is different to Cytopia's other lead compound, which is being developed for use in hormone refractory prostate cancer, although it acts on the same family of targets, Healey explained.

And the molecule may act on more than one kinase, he said, a possibility the company is keen to follow up.

Cytopia is now planning to finish pre-clinical development of the inhibitor, with the aim of doing toxicology studies in the middle of the year.

"We don't need to do much more to the molecule, we're almost at the top of the hill," Healey said. The company plans to do more in vivo efficacy in a range of leukaemias, before selecting the final clinical candidate.

Cytopia's other lead compound should also be ready for toxicology mid year. The company has been "tweaking" the molecule to increase its half life, which has also resulted in greater potency, said Healey, and just a few more animal studies are needed before it's ready to go.

The stock market reacted favourably to the announcement, with Medica's share price up more than 21 per cent to $AUD0.90 at the time of writing.