Atu027 Phase I/II Update

8 August 2013

Update on current Atu027 Phase I/II trial: First patient dosed in the Phase IIa part of the study; extension into a multi-center study

Silence Therapeutics plc ("Silence" or the "Company"), a leading RNA interference (RNAi) company, provides the following update.

Continuation of Phase I/II combination trial on the RNAi therapeutic Atu027 with gemcitabine in first line pancreatic cancer patients (Atu027-I-02/NCT01808638)

Following the completion of the safety lead-in part of the study (announced 18 June 2013), Silence has commenced dosing the first patient in a Phase IIa part of the current Atu027-I-02 study. In this study, first-line patients with loco-regionally advanced or metastatic pancreatic cancer are given two different Atu027 treatments on top of the standard gemcitabine regime, the standard chemotherapy for these patients. In pancreatic cancer, the tumor micro-environment is implicated in fostering tumor growth, invasion and metastasis. The novel investigational drug combination aims to attenuate further disease progression by combining the anti-neoplastic activity of gemcitabine with the anti-metastatic action of Atu027.

We are taking this opportunity to open additional centers in Germany, which is allowed under the current BfArM approval for human testing of Atu027. The University Hospital Freiburg (Germany) will become active in the next few weeks. Further centers are being considered.

Professor Hubert Blum from University Hospital Freiburg commented: "We are pleased to join the Marienhospital in Herne Germany, which concluded and presented the Phase I safety study of Atu027 as a monotherapy in advanced cancer patients at the American Society of Clinical Oncology meeting in June 2013. This current study looking at the potential anti-metastatic effect of Atu027 in conjunction with a conventional chemotherapy, gemcitabine, is a logical next step in the development of Atu027. I look forward to seeing this program progress."

Additional information about this trial can be found at www.clinicaltrials.gov.

For further information contact: