A drug being developed by Biogen Idec and Vernalis for Parkinson‘s disease has been discontinued, news which has hurt the UK firm’s share price significantly.

The companies revealed that vipadenant, a novel adenosine A2A receptor antagonist, achieved positive results in Phase II studies. However, a decision has been taken to discontinue the drug, also known as V2006/BIIB014, “based on a review of findings in preclinical toxicology studies”.

Nevertheless, the partners are not giving up on their collaboration, which began in 2004. They are continuing their A2A receptor antagonist programme for Parkinson’s with a next-generation Vernalis compound which is expected to go into Phase I studies in early 2011.

Biogen will continue to fund all development costs under the collaboration and Vernalis said it can earn milestones and royalties on the successful development of the next-generation compound, “to the extent that milestones have not already been paid for vipadenant. The London-headquartered firm’s chief executive, Ian Garland, said Vernalis was “of course, disappointed” about vipadenant but hopes are high for the new drug.

Mr Garland’s enthusiasm was not particularly shared by investors and Vernalis shares ended the day down 6.4% at 32.50 pence, though they dipped to 30 pence immediately after the announcement.