Silence Therapeutics and InteRNA Technologies sign collaboration to develop novel microRNA therapeutics

September 12, 2011

Collaboration to investigate potential of AtuPLEX™ in the development of novel microRNA therapeutics targeting cancer

London, UK & Nijmegen/Utrecht, Netherlands, September 12, 2011 –
Silence Therapeutics plc (AIM: SLN) (“Silence”), a leading global RNA interference (RNAi) therapeutics company, and InteRNA Technologies B.V. (“InteRNA”), a biopharmaceutical company developing pathway targeted microRNA (“miRNA”)-based therapeutics for cancer, today announce that they have entered into an agreement to develop novel microRNA therapeutics for the treatment of cancer. This will combine the delivery capabilities of Silence’s proprietary AtuPLEX™ delivery system with InteRNA’s novel microRNAs.

Silence is currently conducting a Phase I trial with Atu027 in patients with advanced solid cancer. Atu027 is based on Silence´ proprietary AtuPLEX™ delivery technology. Interim data analysis from this trial were presented at the 2011 American Society of Clinical Oncology conference and showed that Atu027 is safe and well tolerated and provided broad support for AtuPLEX™ as an effective siRNA delivery technology with the potential to overcome the delivery challenges currently associated with RNAi therapeutics.

Under the terms of the agreement, InteRNA will provide Silence with specific miRNA sequences, which Silence will formulate with its AtuPLEX™ delivery system in order to develop multiple candidate drugs. Silence and InteRNA will undertake in vitro and in vivo studies of the candidate drugs developed under the agreement and select lead candidates for further evaluation. Silence is eligible to receive upfront fees as well as staged research payments. Further financial terms of the deal were not disclosed.

Thomas Christély, Chief Operating Officer of Silence Therapeutics, said: “We are pleased to be collaborating with InteRNA, and it is in our interest to broaden the potential value of our AtuPLEX™ delivery system as a vehicle to modify gene expression using different oligonucleotide classes, alongside our continuing focus on our internal siRNA therapies. Functional delivery into target cells is one of the greatest challenges facing most nucleic acid therapies. Silence remains committed to the development of its AtuPLEX™ and other delivery systems including DACC and DBTC as it seeks to overcome these challenges.”

Dr Roel Schaapveld, Chief Executive Officer of InteRNA Technologies, said: “We are very excited about this collaboration with Silence. Working with AtuPLEX™ and the experienced team at Silence fits perfectly in our strategy to address the delivery challenge of RNA based therapeutics upon systemic administration. AtuPLEX™ may significantly contribute to the efficacy of several miRNA drug candidates in our pipeline that have shown to reduce tumor growth in vivo and as such supports further development of these drug candidates towards the clinic.”

For further information, please contact:

Silence Therapeutics
Max Herrmann
+44 20 7491 6520
m.herrmann@silence-therapeutics.com

InteRNA Technologies B.V.
Dr Roel Schaapveld
+31 24 352 96 33
schaapveld@interna-technologies.com

Singer Capital Markets
Shaun Dobson/Claes Spång
+44 20 32057500
shaun.dobson@singercm.com
claes.spang@singercm.com

M:Communications (Europe) Peter Laing / Emma Thompson
+44 20 7920 2345 / +44 20 7920 2342
healthcare@mcomgroup.com

Vida Communication (US)
Tim Brons (media)/Stephanie Diaz (investors)
+1 (415) 675-7400
tbrons@vidacommunication.com
sdiaz@vidacommunication.com

Notes for editors

About Silence Therapeutics plc (www.silence-therapeutics.com)
Silence Therapeutics plc (AIM: SLN) is a leading biotechnology company dedicated to the discovery, development and delivery of targeted, systemic RNA interference (RNAi) therapeutics for the treatment of serious diseases. Silence offers one of the most comprehensive short interfering RNA (siRNA) therapeutic platforms available today based on a strong intellectual property portfolio and large clinical safety database. Silence’s clinical siRNA product pipeline is one of the broadest in the industry. The Company possesses multiple proprietary siRNA delivery technology platforms including AtuPLEX™ and DACC. AtuPLEX enables the broad functional delivery of siRNA molecules to targeted diseased tissues and cells, while increasing their bioavailability and intracellular uptake. The DACC delivery system allows functional delivery of siRNA molecules selectively to the lung endothelium with a long duration of target mRNA and protein knock-down. Additionally, the Company has a platform of novel siRNA molecules based around its AtuRNAi chemical modification technology, which provides a number of advantages over conventional siRNA molecules. Silence’s unique RNAi assets also include structural features for RNAi molecules and specific design rules for increased potency and reduced off-target effects of siRNA sequences.
The Company’s lead internal drug candidate is Atu027, a liposomal formulation in clinical development for systemic cancer indications and one of the most clinically advanced RNAi therapeutic candidates in the area of oncology. Atu027 incorporates two of the Company’s technologies, AtuRNAi and AtuPLEX™. Silence is currently conducting an open-label, single-centre, dose-escalation Phase I study with Atu027 in patients with advanced solid tumors involving single, as well as repeated, intravenous administration. Encouraging interim data were presented at the American Society of Clinical Oncology Annual Meeting in June 2011. The study is expected to be completed in the second half of 2011.
The Company’s RNAi therapeutic platform has received key validation through multiple partnerships with pharmaceutical companies including AstraZeneca, Dainippon Sumitomo, Pfizer/Quark, and Novartis/Quark. Silence is actively pursuing the establishment of additional partnerships. Silence Therapeutics has operations in both Berlin and London.

About InteRNA Technologies B.V. (www.interna-technologies.com)
InteRNA Technologies is a Dutch early-stage drug discovery and development company that develops pathway targeted cancer therapies based on the unique functions of its proprietary microRNAs (“miRNAs”).
InteRNA takes an holistic approach in R&D to unravel the biological role of its proprietary miRNAs focusing on the demonstration of their function in a number of cancer indications through functional screens, using its proprietary lentiviral-based miRNA expression library, currently the largest available. This approach results in the identification of novel, “drugable” targets, providing a steady basis for further validation and drug development.
InteRNA Technologies was incorporated in December 2006 by Aglaia Oncology Fund and has established close relationships with the research groups of its founders Edwin Cuppen, PhD, and Eugene Berezikov, PhD, of the Hubrecht Institute (Utrecht, the Netherlands), leading scientific groups in the field of miRNA research. The company further has a series of R&D partnerships with Dutch- and US-based academic hospitals and research institutes.

About MicroRNAs (miRNAs)
MicroRNA (miRNA) are naturally occurring, non-coding strands of RNA that trigger the RNA interference pathway. They result from an extensive processing route in which a long RNA transcript, folded in a hairpin structure, is cleaved into short strands of approximately 22 nucleotides - the miRNA molecules.
MiRNAs regulate gene expression by controlling the efficiency of messenger RNA (mRNA) translation - the process of translating genetic information into proteins. The miRNA binds to its target sequence in mRNA transcripts, leading to translational repression or mRNA degradation. As a result, the production of the protein encoded by that particular mRNA sequence is inhibited.
So far, approximately 940 human miRNA sequences have been documented. For many of these it is not clear what genes they target. However, some miRNAs have been reported to regulate the expression of genes involved in differentiation and cell growth, tumor suppressors and oncogenes. Each miRNA may regulate the expression of multiple genes. miRNAs are now recognized as one of the key regulators of gene expression, involved in almost every aspect of a cell life from cell differentiation to apoptosis, although specific functions have so far only been elucidated for a handful of miRNAs.

Forward-Looking Statements
This press release includes forward-looking statements that are subject to risks, uncertainties and other factors. These risks and uncertainties could cause actual results to differ materially from those referred to in the forward-looking statements. All forward-looking statements are based on information currently available to Silence Therapeutics and Silence Therapeutics assumes no obligation to update any such forward-looking statements.