Roche and Evotec have pulled the plug on an antidepressant which was in mid-stage trials, a move which has seen the German biotech's share price suffer.

The firms have decided to voluntarily terminate the Phase II study in treatment-resistant depression with EVT101, their NR2B sub-type selective N-methyl-D-aspartate (NMDA) antagonist, a decision "triggered by difficulties to recruit patients under the current study protocol, resulting in the possibility of inconclusive results". Evotec noted that "the need to sharpen the toxicology profile and a potential requirement for an altered dosage scheme led to an overall delay in the programme".

This is a major blow for the Hamburg-based firm as the programme "has been the key part" of the alliance with Roche. The Swiss firm had provided all funding in exchange for certain option rights after a proof-of-concept result that has not been forthcoming.

Evotec noted that it retains all rights in the EVT100 series, especially the back-up compound EVT103, "and will enter into partnering discussions for these assets". Finding one is key as the company "noted that advanced clinical development of drug candidates is not part of Evotec's core business".

The bad news about the Roche pact comes a week after Evotec announced first-quarter revenues of 15.1 million euros, up 54%, while its operating loss fell 45% to 800,000 euros. The company said that for 2011, it was expecting at least 15% revenue growth to 64-66 million euros and "increased operating profitability over 2010".

That guidance may need changing now that EVT1010 has bitten the dust and Evotec's shares ended the day down 8.8% to 2.71 euros.