SLN.L Regulatory News (SLN)

24 Oct 2011 07:00

FOR IMMEDIATE RELEASE

Silence Therapeutics signs collaboration with Mirna Therapeutics to evaluate

delivery of novel microRNA therapeutics -- Collaboration to investigate potential application of Silence's novel

AtuPLEXâ„¢and DBTC delivery technologies in the development of novel microRNA

therapeutics targeting cancer-- London, UK October 24, 2011 -Silence Therapeutics plc (AIM: SLN) ("Silence"), aleading RNA interference (RNAi) therapeutics company, today announced that ithas entered into an agreement with Mirna Therapeutics Inc. ("Mirna"), abiopharmaceutical company pioneering microRNA-based therapeutics for cancer, toassess the delivery capabilities of Silence's proprietary AtuPLEXâ„¢ and DBTCdelivery systems for Mirna's novel microRNAs.

Under the terms of the agreement, Mirna will provide Silence with specific miRNA sequences, which Silence will formulate with its AtuPLEXâ„¢ and DBTC delivery systems in order to develop multiple candidate drugs. Mirna will undertake in vitro and in vivo studies of the candidate drugs developed under the agreement and select lead candidates for further evaluation. Financial terms of the deal were not disclosed.

Thomas Christ©ly, Chief Executive Officer of Silence Therapeutics, said: "Weare delighted to be collaborating with Mirna. This is our second collaborationexploring the use of Silence's delivery technologies to deliver microRNAs.However, it is Silence's first collaboration involving our new DBTC liverdelivery system. Whilst internally we remain focused on the delivery of oursiRNA therapies, we continue to look to broaden the potential value of ourdelivery systems by partnering them with other companies for use in multipleapplications. Functional delivery of effective doses into target cells is oneof the greatest challenges facing most nucleic acid therapies. With ourdelivery systems AtuPLEXâ„¢, DACC and DBTC, Silence has an increasing range ofdelivery options to help overcome these challenges."Paul Lammers, MD, President and Chief Executive Officer of miRNA Therapeutics,said:"We are very interested to be working with Silence Therapeutics on thedelivery of our miRNAs, as Silence has clearly been shown to be at theforefront of efficient and safe delivery of siRNAs and miRNAs, a processcritical to the ultimate success of what promises to be a new and excitingclass of targeted cancer therapeutics. Mirna has developed a strongintellectual property position in the therapeutic use of miRNAs in cancer, andhas established a broad pipeline of key tumor suppressor miRNAs as potentialnew targeted therapeutic candidates against both solid and haematologicalcancers. An efficient delivery technology that provides for systemic deliveryof therapeutically effective dose-levels of these miRNAs to their intendedtargets is a key element in their potential success in the clinic."Silence's proprietary lipid delivery technology AtuPLEXâ„¢ has demonstrated thebroad systemic delivery to the vascular endothelium. Formulations generatedwith the AtuPLEXâ„¢ technology can be lyophilized (freeze dried) significantlyimproving stability, shipping and handling.Silence is currently conducting a Phase I trial with Atu027 which is based onAtuPLEXâ„¢ in patients with advanced solid cancer. Interim data analysis fromthis trial were presented at the 2011 American Society of Clinical Oncologyconference and showed that Atu027 is safe and well tolerated and provided broadsupport for AtuPLEXâ„¢ as an effective siRNA delivery technology with thepotential to overcome the recognized delivery challenges currently associatedwith RNAi therapeutics.DBTC is the latest delivery system developed by scientists at Silence andallows functional targeted delivery to the liver. Unlike Silence's establisheddelivery technologies, DBTC is a novel lipid-based formulation thatfunctionally delivers to liver endothelial cells, hepatocytes and to other celltypes of the liver. As with AtuPLEXâ„¢, DBTC can be lyophilized. --Ends--

For further information, please contact:

Silence Therapeutics Mirna Therapeutics Thomas Christ©ly/Max Herrmann Paul Lammers, MD +49 30 9489 2800/+44 20 7491 6520 +1 512 901 0909 t.christely@silence-therapeutics.com plammers@mirnarx.com m.herrmann@silence-therapeutics.com

Singer Capital Markets M:Communications (Europe) Shaun Dobson/Claes Sp¥ng Peter Laing / Emma Thompson +44 20 32057500 +44 20 7920 2345 / +44 20 7920 2342 shaun.dobson@singercm.com healthcare@mcomgroup.com claes.spang@singercm.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 companydedicated to the discovery, development and delivery of targeted, systemic RNAinterference (RNAi) therapeutics for the treatment of serious diseases. Silenceoffers one of the most comprehensive short interfering RNA (siRNA) therapeuticplatforms available today based on a strong intellectual property portfolio andlarge clinical safety database. Silence's clinical siRNA product pipeline isone of the broadest in the industry. The Company possesses multiple proprietarysiRNA delivery technology platforms including AtuPLEXâ„¢, DACC and DBTC. AtuPLEXenables the broad functional delivery of siRNA molecules to targeted diseasedtissues and cells, while increasing their bioavailability and intracellularuptake. The DACC delivery system allows functional delivery of siRNA moleculesselectively to the lung endothelium with a long duration of target mRNA andprotein knock-down. The DBTC delivery system enables functional delivery ofsiRNA molecules selectively to liver cells including hepatocytes. Additionally,the Company has a platform of novel siRNA molecules based around its AtuRNAichemical modification technology, which provides a number of advantages overconventional siRNA molecules. Silence's unique RNAi assets also includestructural features for RNAi molecules and specific design rules for increasedpotency and reduced off-target effects of siRNA sequences.The Company's lead internal drug candidate is Atu027, a liposomal formulationin clinical development for systemic cancer indications and one of the mostclinically advanced RNAi therapeutic candidates in the area of oncology. Atu027incorporates two of the Company's technologies, AtuRNAi and AtuPLEXâ„¢. Silenceis currently conducting an open-label, single-centre, dose-escalation Phase Istudy with Atu027 in patients with advanced solid tumors involving single, aswell as repeated, intravenous administration. Encouraging interim safety andpharmacokinetic data were presented at the American Society of ClinicalOncology Annual Meeting in June 2011. The study is expected to be completed inthe first half of 2012.

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 Mirna Therapeutics Inc. (www.mirnarx.com)

Mirna Therapeutics is a biotechnology company focused on the development andcommercialization of microRNA (miRNA) therapeutics. The Company has asubstantial body of intellectual property around miRNAs developed by its ownscientists as well as in-licensed from other institutions. Mirna's IP portfoliocontains >300 miRNAs with applications in oncology and other diseases.Oncology-directed miRNAs include those that are key tumor suppressors incancer, such as miR-34 and let-7 that have proven to block tumor growth in anumber of different pre-clinical animal studies. The Company, founded in 2007,is located in Austin, Texas.About MicroRNAs (miRNAs)

miRNAs are approximately 20-25 nucleotides long and affect gene expression byinteracting with messenger RNAs. Unlike siRNAs, miRNAs are encoded in the humangenome and are used as natural regulators of global gene expression. More than1,400 miRNAs are encoded in the human genome and comprise approximately 2% ofall mammalian genes. Since each miRNA appears to regulate the expression oftens to hundreds of different genes, miRNAs can function as "master-switches,"efficiently regulating and coordinating multiple cellular pathways andprocesses. By coordinating the expression of multiple genes, miRNAs areresponsible for guiding proper embryonic development, immunity, inflammation,as well as cellular growth and proliferation. Misregulation of miRNAs appearsto play a fundamental role in many cancers and replacement of down regulatedmiRNAs in tumor cells results in a positive therapeutic response

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.