The US regulators have refused to approve Abbott Laboratories' experimental prostate cancer drug, Xinlay, which failed to delay progression of the disease in two clinical trials.

The drugmaker said in a regulatory filing the US FDA deemed the medicine "not approvable." The decision comes after an advisory panel last month unanimously urged the agency to reject the drug, saying it lacked effectiveness in two trials involving patients whose cancer had already spread, said report.

The company would continue to study the drug in an ongoing late-stage trial involving nearly 1,000 men whose cancer has not yet spread. Abbott said the FDA decision does not affect that trial, adds the report.

The two earlier trials failed their primary goal, which was to show that Xinlay delayed progression of the disease. Even so, Abbott urged the FDA to approve it, saying the drug seemed to relieve bone pain among patients whose prostate cancer had spread to the bones, states the report.