Silence Therapeutics plc and AstraZeneca has extended their ongoing research and development collaboration by one year. Under the terms of the agreement, which has progressed well since being signed in July 2007, Silence and AstraZeneca are jointly collaborating in the identification and optimization of five novel siRNA therapeutic molecules addressing respiratory and oncology indications.

Silence's team interacts closely with several of AstraZeneca's operational units including Medimmune in the US and AstraZeneca teams in Sweden, the UK and China to progress the development of the siRNA molecules identified as a result of the collaboration. Under the terms of the agreement, AstraZeneca will retain full responsibility for clinical development and commercialization of the siRNA molecules. As announced previously, in addition to the initial £7.5 million access fee paid to Silence in July 2007, the collaboration may generate up to £200 million in fees and milestone payments plus royalties on product sales. The terms of this collaboration agreement are independent of Silence's siRNA delivery collaboration with AstraZeneca which was also extended in April this year.

Commenting on today's announcement, Philip Haworth, chief executive officer of Silence, said, "The extension of our development collaboration with AstraZeneca is testament to the successful relationship and the progress made in this collaboration. Both teams are working closely together to optimize the five therapeutic programs based on Silence's leading siRNA technology, in addition to our collaboration investigating new delivery approaches for RNA interference. AstraZeneca is a strong endorsement of our technology and we are delighted to continue working together."

Thomas Eichholtz, vice president Respiratory and Inflammation Research Area of AstraZeneca, commented, "AstraZeneca remains committed to the development of new therapeutic technologies that have the potential to create novel therapies. We are very pleased with the progress we have made in our collaborative agreement with Silence Therapeutics."

Silence Therapeutics plc is a leading global biotechnology company dedicated to the discovery, development and delivery of targeted, systemic RNA interference (RNAi) therapeutics for the treatment of serious diseases.