Germany’s Bayer has signed a deal with US pharmaceutical firm Nuvelo for rights to develop and market its investigational blood clot buster, alfimeprase.

Under the terms of the agreement, Nuvelo could get up to $385 million in milestone payments, including a $50 million upfront fee and royalties of 15.0%-37.5%, depending on sales. The group expects to glean around $90 million this year from the deal, a prospect that helped ignite a flurry of investor activity yesterday fuelling a 41% leap in Nuvelo’s share price to $12.67.

The US firm will pay 60% of the global development costs and will continue to rule over the design and progression of the agent’s development path, while Bayer will take responsibility for the remaining 40%. Nuvelo holds commercialisation rights in its domestic market and Bayer will sell the agent in all other territories.

Alfimeprase, an enzyme that rapidly breaks down blood clots by attacking their internal fibrin scaffolds, is also in Phase III clinical trials for the treatment of catheter and blood vessel blockages in the periphery, and may be effective in treating stroke, deep venous thrombosis and heart attack. According to media reports, a US market launch for product is planned for 2008, followed by a European introduction in 2009.

The deal represents an important move for both companies, and adds to the recent trend of pharma giants buying innovative candidate drugs from smaller firms to bolster their pipelines.

The purchase will help Bayer strengthen its presence in the anti-thrombotic market, joining candidates such as the group’s Factor Xa inhibitor, an oral antithrombotic currently in Phase III trials. Nuvelo, on the other hand, is depending on cash from the deal to drive further research into the other potential uses for alfimeprase.