BioWorld International Correspondent

Paion AG gave its beleaguered investors a little autumnal cheer by raising hopes that its clot-busting stroke drug Desmoteplase might return to the clinic, despite a Phase III clinical trial miss earlier this year that precipitated a share price plunge.

Following a detailed subgroup analysis of the trial data, the Aachen, Germany-based company said it has obtained evidence explaining the unexpectedly high placebo response seen in the study, dubbed DIAS-2 (Desmoteplase in Acute ischemic Stroke). (See BioWorld Today, June 4, 2007.).

"We believe we now have at least a scientific rationale to move forward," company spokesman Peer Nils Schroeder told BioWorld International.

Angiograph data reveal that a high percentage of patients in DIAS-2 did not have a blood clot in one of the main arteries of the brain, the company said, despite the presence of salvageable brain tissue or a penumbra surrounding the infarct core, as defined by the study protocol. In earlier Phase II studies, in which Desmoteplase demonstrated efficacy, a higher percentage of patients did have major arterial occlusions.

Previously, the presence of a penumbra was taken as a key indicator of the presence of both detectable and undetectable clots. Paion and its clinical collaborators now believe that it is necessary to assess the location of the occlusion as well, in order to optimize treatment.

"It's some new scientific knowledge on how to assess stroke patients that has come out as a result of the trial," Schroeder said. The company plans to publish the relevant data.

The new information should not have any impact on the use of Desmoteplase in clinical settings, he said, as angiography is now routinely used to exclude patients suffering from an aneurysm from receiving thrombolytic therapy.

Desmoteplase did show strong signs of efficacy in patients who did have a major vessel blockage, Schroder said, although this signal was not statistically significant, given the high placebo effect seen in the trial.

Despite the renewed scientific optimism, however, Paion is still seeking a commercial rationale for taking Desmoteplase forward. The company is not prepared to pursue additional studies on its own and is seeking a development partner to either co-finance or to underwrite the cost of a new trial in its entirety.

Its North American partner, Forest Laboratories, Inc., of New York, terminated its interest in the program in late August. (See BioWorld International, Sept. 5, 2007). European partner H. Lundbeck A/S, of Copenhagen, Denmark, is still considering its options, and it may not arrive at a decision before the year end, Schroeder said.

The news lifted Paion's share price to €3.43 (US$4.89) in Frankfurt last Thursday, having closed the previous day at €1.51. It latter shed some of these gains, closing Tuesday at €2.65. The stock had been trading at €10.50 immediately before the trial data were disclosed.