New Data from Silence Therapeutics plc's Atu027 Anticancer Trial Published at American Society of Clinical Oncology

LONDON, May 17, 2012 /PRNewswire/ --

- Atu027, a First in Class RNAi Therapy, Demonstrates Potential

- Antitumour Activity in Cancer Patients and Possible Biomarker Identified

Silence Therapeutics to Announce New Data from Phase I Study of Atu027 in Solid Tumours At 2012 ASCO Annual Meeting

Silence Therapeutics plc (AIM: SLN) ("Silence" or the "Company"), a leading global RNA interference (RNAi) therapeutics company, today announces that top line data from its ongoing Phase I trial of Atu027 show that of the 33 patients treated in the first 10 cohorts of the study, 10 patients experienced stable disease after three months. Two patients with neuroendocrine cancers had disease stabilisation for nine and 12 months respectively, including partial regression of liver metastases in one patient. Another patient with breast cancer demonstrated regression of liver metastases. Importantly, among various biomarkers tested, sVEGFR-1 plasma levels decreased significantly upon treatment further confirming a potential biological effect of Atu027.

Silence will publish the latest data from its ongoing Phase I study of Atu027, its lead internal therapeutics candidate, at the 2012 American Society of Clinical Oncology ("ASCO") Annual Meeting in Chicago, Illinois, 1-5 June 2012. Further data from the ongoing Phase I Atu027 clinical study will also be the subject of a presentation with the following details:

    Abstract Title:     Anti-metastatic activity of Atu027, a liposomal small
                        interfering RNA formulation, targeting protein kinase
                        N3 (PKN3): Final results of a phase I study in
                        patients with advanced solid tumours.
    Abstract #:         98347
    Presentation
    Date/Time:          Mon, June 04, 2012 / 16:00 - 18:00
    
    Location:           Networking Lounge, Level 3, North    Presenters:         Klaus Giese
                        [http://silence-therapeutics.com/about-us/management],
                        Ph.D., chief scientific officer of Silence, and Dr.
                        Dirk Strumberg, Professor of Medicine and Director,
                        Department of Hematology and Medical Oncology,
                        University of Bochum, Marienhospital Herne, the
                        study's principal investigator    Attendees           Please contact c.jahn@silence-therapeutics.com for
                        further information

Silence's open label, single-centre, dose-finding Phase I study of Atu027 in subjects with advanced solid cancer is ongoing. The study was designed to evaluate up to a total of 11 escalating doses of Atu027 and enroll approximately 33-36 patients. Across the nine completed dose levels, Atu027 was generally well tolerated with no dose-limiting toxicities observed. Additionally, as consistent with preclinical data, preliminary Phase I pharmacokinetic (PK) data showed dose-dependent increase in plasma siRNA and lipid levels.

Silence expects to complete the ongoing Phase I clinical trial of Atu027, one of the most clinically advanced RNAi therapeutics in the area of oncology, in July 2012. The full ASCO abstract for the Phase I Atu027 study is now available online at: http://chicago2012.asco.org/.

"I am delighted that with Atu027 we potentially have a first in class RNAi therapeutic for treating solid tumours. Cancer therapy needs innovative treatments such as Atu027. The new data at ASCO demonstrates that Atu027 can be safely administered at doses above those believed to be effective. Moreover, the data also strongly indicate that Atu027 is impacting the disease course and in particular providing disease stabilisation." said Tony Sedgwick, Ph.D., chief executive officer of Silence Therapeutics. "Identification of sVEGR-1 as a possible biomarker is also a significant new advancement and we look forward to sharing more complete findings from the ongoing Phase I study at ASCO in June."

About Atu027

Atu027 is a liposomal siRNA formulation targeting PKN3 for the treatment of advanced solid cancer. PKN3 is a key regulator during angiogenesis and lymphangiogeneis, while also acting as a major regulator of metastasis and motility during pathological processes. Accordingly, Silence believes that inhibition of PKN3 with Atu027 may lead to a reduction in nutrient and oxygen supply to solid tumors, as well as interfering with tumor formation, endothelial cell motility and metastasis.

Notes for editors

About Silence Therapeutics plc (http://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, DACC and DBTC. 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. The DBTC delivery system enables functional delivery of siRNA molecules selectively to liver cells including hepatocytes. 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 safety and pharmacokinetic data were presented at the American Society of Clinical Oncology Annual Meeting in June 2011. The study is expected to be completed in July 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.

For further information, please contact:
Silence Therapeutics
Tony Sedgwick / Max Herrmann
T: +44-20-7491-6520
a.sedgwick@silence-therapeutics.com
m.herrmann@silence-therapeutics.com

M: Communications
Mary-Jane Elliott / Sarah Macleod /
Claire Dickinson
T: +44-20-7920-2330
silencetherapeutics@mcomgroup.com

Singer Capital Markets
Shaun Dobson / Claes Spång
T: +44-20-3205-7500
shaun.dobson@singercm.com
claes.spang@singercm.com

SOURCE Silence Therapeutics Plc