Danish biotechnology company Santaris Pharma has received another cash injection from partner Pfizer as part of their alliance to develop nucleic acid-based medicines.

In the re-negotiated deal, Santaris gets another $14 million payment from Pfizer upfront and could reap as much as $600 million in milestone payments over the course of the collaboration, as well as royalties on sales.

The roots of the deal come from a 2009 licensing deal between Santaris and Wyeth, which Pfizer acquired in the same year. Santaris' projects have survived a major R&D shake-up at Pfizer in the wake of the mega-merger, which resulted in six facilities being closed down and a complete review of all the combined firm's drug development operations.

"Pfizer has advanced several programs under the original collaboration and reached a number of early milestones since the inception of the collaboration," said Santaris in a statement.  The company's main technology is its Locked Nucleic Acid (LNA) platform, which allows it to rapidly create and develop drug candidates against RNA targets.

The Danish firm claims its LNA drugs have advantages over existing nucleic acid-targeting approaches, such as antisense and small, interfering RNA (siRNA),  particularly with regard to their pharmacokinetics and tissue-penetrating properties which allow systemic delivery.

Santaris' most advanced project (not partnered with Pfizer) is miravirsen for hepatitis C, said to be the first drug to enter clinical trials which targets microRNA, an important class of small RNAs encoded in the genome. It is currently in Phase II testing. Pfizer's programmes are all at the lead discovery phase.