Brisbane's Progen Pharmaceuticals [ASX: PGL] has abandoned its PI-88 liver cancer trials, sending its share price tumbling by almost 50 per cent.

PI-88, a heparin sulphate mimic with anti-angiogenic and anti-metastatic properties, was undergoing Phase III trials prior to the termination, but was experiencing significant delays in patient recruitment and obtaining regulatory approval, the company said.

Another factor contributing to the decision was the recent news that pharma giant Bayer and collaborator Onyx Pharmaceuticals have commenced trials of a competitor product, Nexavar, a kinase inhibitor targeting angiogenesis.

Progen also had trouble finding a partner willing to help develop and commercialise the product.

Progen will shortly commence discussions with its partners and others over the sale of the compound, it said.

The company, which began as a pharmaceutical manufacturing concern, said it would now concentrate on mergers and acquisitions.