Clinical trial update

14 May 2015

Silence Therapeutics plc

Clinical trial update

Silence Therapeutics plc, AIM: SLN, ("Silence" or "the Company"), a leader in the development and delivery of novel RNA therapeutics, announced on 23 March 2015 preliminary analysis of its Phase 2a trial of Atu027 in pancreatic cancer (Atu027-I-02). The positive results have led the Board to review its strategic use of resources in cancer, including the design and initiation of the proposed head and neck cancer study.

The Company believes that the implication of higher and more frequent dosing warrants investigation prior to a full Phase 2 study in pancreatic cancer patients. As a result, the head and neck cancer study, as originally designed, has been deferred to enable the Company to explore this dosing issue further.

Once the dosing regimen has been optimised in pancreatic cancer, other metastatic cancers like head and neck can be addressed. At this stage the Company will focus on achieving definitive success in pancreatic cancer, measured in terms of clear endpoints. A further statistical analysis of the pancreatic cancer study, which is expected to confirm the early indications of benefit of Atu027, will be made available in the Company's AGM statement, which is due to be released on 1 June 2015.

Ali Mortazavi, CEO of Silence Therapeutics, said:

"The clear signal that was detected in the early analysis of this trial data has encouraged us to allocate existing resource to pursue pancreatic cancer as our main focus at present.

"An indication in head and neck cancer remains a consideration for the future, but our priority is to progress our drug through definitive clinical trials in pancreatic cancer patients."

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About Silence Therapeutics (www.silence-therapeutics.com)

Silence Therapeutics is a leading RNA therapeutics company. It has developed proprietary modifications to improve the robustness of RNA sequences together with advanced liposomal chemistries to enhance the delivery of its therapeutics. Its technology can selectively silence or replace the expression of any gene in the genome, modulating expression up as well as down in a variety of organs and cell types, in vivo. This allows the development of therapeutics for diseases with high unmet clinical need. Silence's technology is currently in the clinic in a Phase 2a pancreatic cancer trial.