Neuroscience biotech firm Cerecor has signed its second pact in a month with Merck & Co as the US giant continues its strategy of out-licensing early-stage therapies.

Cerecor has acquired exclusive, worldwide rights to develop and commercialise MK-0657 for all human indications, including depression. The drug, a small molecule NMDA receptor subunit 2B (NR2B) antagonist, was initially developed by Merck for the treatment of Parkinson's disease.

Under the terms of the agreement, the financial terms of which have not been disclosed, Cerecor will pay milestones and royalties "consistent with clinical stage licences in neuroscience". Technology transfer activities should be completed by mid-2013 and clinical trials will then start.

James Vornov, Cerecor's head of clinical development and regulatory affairs, said MK-0657 is "a potential first-in-class, best-in-class, oral medication that is complementary to existing treatments in depressed patients who have failed to respond to available therapies". He added that "we are particularly interested in the potential to rapidly reduce depressive symptoms, including suicidal ideation, in these severely affected patients".

The deal comes a month after Cerecor acquired rights to develop agents that inhibit catechol-O-methyltransferase (COMT) inhibitors from Merck.

Drugs that inhibit COMT have been used to treat patients with Parkinson’s but Cerecor says they have poor brain penetration and limited safety and tolerability. The biotech adds that COMT inhibition also has broad potential applicability in other CNS diseases, such as addictive behaviours and schizophrenia.

Under the terms of that agreement, Cerecor will evaluate more than 2,000 molecules and select lead candidates for clinical development.