Significant Expansion of Intellectual Property

Significant expansion of Intellectual Property (March to May 2017)

16 May 2017

Silence Therapeutics plc, AIM:SLN ("Silence" or "the Company") a leader in the discovery, delivery, and development of novel RNA therapeutics for the treatment of serious diseases with unmet medical need, announces a significant expansion of its chemical modification patent estate.

As previously announced in March 2017, the European Patent Office granted patent EP 2258847B. This granted patent provides Silence with further protection for its innovative chemical modification technology across many European countries. We believe this patented technology is relevant to third party medicines in ongoing clinical trials for conditions including, but not exclusively limited to, Hypercholesterolemia, TTR-mediated Amyloidosis, Haemophilia and Acute Hepatic Porphyrias.

Subsequently, in May 2017, Silence has expanded and strengthened its above patent estate by filing additional divisional and continuation patent applications in Europe and the US respectively. We believe these applications are also relevant to the third-party medicines listed above. Chemical modification technology is vital to prevent the degradation of therapeutic short interfering RNA (siRNA) molecules and to enable potent RNA interference (RNAi). The use of such technology has a substantial impact on the performance of RNAi based drugs.

Silence may consider granting licences under its intellectual property (IP). Previously, Quark Pharmaceuticals was granted a royalty and milestone licence under the same patent estate for certain products currently in Phase II and Phase III, which are partnered with Novartis. Importantly, the licence to Quark was granted at a pre-clinical stage in 2005, whereas the medicines for the above listed conditions are in late-stage clinical development.

Ali Mortazavi, Chief Executive Officer of Silence Therapeutics, commented:

"These granted patents and patent applications within the US and Europe are key to our leading IP position in the RNAi field and build upon the pivotal nature of Silence's innovation, enabling our core drug development business. In addition, we believe that several third party late-stage clinical RNAi candidates, including lipid nanoparticle and GalNAc based products, require licences under our patent portfolio. The first launch for these medicines is anticipated in 2018. We consider that potential licences under our patent estate could have a significant financial effect relative to the current market capitalisation of Silence."

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About Silence Therapeutics plc

Silence Therapeutics develops a new generation of medicines by harnessing the body's natural mechanism of RNA interference, or RNAi, within its cells. Our proprietary technology can selectively inhibit any gene in the genome, specifically silencing the production of disease-causing proteins. Using our enabling delivery systems, we have achieved an additional level of specificity by delivering our therapeutic RNA molecules exclusively to target cells. Silence's proprietary RNA chemistries and delivery systems are designed to improve the stability of our molecules and enhance effective delivery to target cells, providing a powerful modular technology well suited to tackle life-threatening diseases.