Update on Litigation Matters

Update on litigation matters

3 November 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 an update on litigation matters. Previously, the Company delivered its claim for declaratory relief relating to its entitlement to Supplementary Protection Certificates (SPCs) on certain Alnylam products, naming as defendants Alnylam UK Limited, Alnylam Pharmaceuticals Inc, and The Medicines Company UK Limited.

Alnylam UK Limited and The Medicines Company UK Limited have sued to revoke the relevant Silence European patent in the UK, and also included claims for declarations of non-infringement of this European patent by certain Alnylam products.

Silence regards the actions taken by the defendants as simply "normal course of business" at the commencement of litigation, and continues to believe that certain Alnylam products require a licence under the Silence patent estate.

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

"During 2017, both the European and US patent offices have continued to uphold the validity of our expanding patent estate with the granting of additional patents. We believe that our fundamental chemical modification technology is core foundational innovation for today's RNAi sector, and that therefore those companies using such modification technology within the scope of our Intellectual Property (IP) will require a licence. Silence is committed to defending its position and to securing the appropriate recognition and associated value for its IP."

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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.