Horizon Discovery Selected as Core Facility

PRESS RELEASE

2nd February 2015

Horizon Discovery Group Selected as Core Facility by Tri-Institutional Therapeutics Discovery Institute

Two year master services agreement signed with an initial work order for $500,000 to carry out drug combination screening and in vitro assay development

Cambridge, UK, 2nd February 2015: Horizon Discovery Group plc (LSE:HZD) (Horizon), the international life science company supplying research tools and services to organizations engaged in genomics research and the development of personalized medicines, today announced that it has been selected to act as a core facility by the Tri-Institutional Therapeutics Discovery Institute (TDI). As a core facility, Horizon will provide single and combination drug profiling followed by confirmatory secondary assay services to TDI through its discovery research services unit.

Under the agreement, Horizon will receive up to $500,000 for work to be performed during 2015 and 2016, with the option for additional collaboration work orders thereafter.

Horizon will utilize its unique cHTS (combination High Throughput Screening) platform and Chalice™ analytics software to screen and analyze potentially thousands of small-molecule drugs, therapeutic antibodies or proteins in combination to identify synergistic or antagonistic interactions. Horizon will also provide a range of optimized cellular assays as follow-ups to identify drug target activity. The first programs are forecast to start in the second half of 2015.

Dr. Darrin M. Disley, Chief Executive Officer of Horizon Discovery Group plc, commented: "Horizon is thrilled to have been chosen as a core facility to support TDI research programs via application of our innovative drug combination screening platform and assay services. The partnership, which provides access to multiple components of our technology platforms and capabilities, reinforces the value that we can provide our customers from 'sequence to treatment'. We look forward to working with the TDI team and potentially broadening our relationship further in 2016 and 2017."

Dr. Michael Foley, Sanders Director, TDI, said: "The Tri-Institutional Therapeutics Discovery Institute links researchers in basic and clinical science with experts in drug discovery from the biotech and pharmaceutical industries, with the goal of more efficiently translating discoveries into therapies for disease. We are delighted to be partnering with Horizon Discovery Group and look forward to initiating the programs."

ENDS

Notes to Editors

For further information from Horizon Discovery Group Plc, please contact:

Consilium Strategic Communications (Financial Media and Investor Relations)

Amber Bielecka / Mary-Jane Elliott / Jessica Hodgson / Matthew Neal

Tel: +44 (0) 20 3709 5701

Email: horizon@consilium-comms.com

Zyme Communications (Trade and Regional Media)

Katie Odgaard

Tel: +44 (0)7787 502 947

Email: katie.odgaard@zymecommunications.com

Panmure Gordon (UK) Limited (NOMAD)

Corporate Finance: Freddy Crossley / Duncan Monteith / Fred Walsh

Broking: Tom Salvesen

Tel: +44 20 7886 2500

About Horizon Discovery Group plc www.horizondiscovery.com/

Horizon is a revenue-generating life science company supplying research tools to organizations engaged in genomics research and the development of personalized medicines. Horizon has a diverse and international customer base of over 1,000 organizations across nearly 50 countries, including major pharmaceutical, biotechnology and diagnostic companies as well as leading academic research centers. The Company supplies its products and services into multiple markets, estimated to total in excess of £29 billion by 2015.

Horizon's core capabilities are built around its proprietary translational genomics platform, GENESIS™, a high-precision and flexible suite of gene editing tools able to alter almost any endogenous gene sequence of human or mammalian cell-lines. Horizon offers almost 14,000 products, almost all of which are based on the application of GENESIS™ to generate cell lines that accurately model the disease-causing mutations found in genetically based diseases. These 'patients-in-a-test-tube' are being used by customers to identify the effect of individual or compound genetic mutations on drug activity, patient responsiveness, and resistance, which may lead to the successful prediction of which patient sub-groups will respond to currently available and future drug treatments.

In addition, Horizon provides GENASSIST™ CRISPR and rAAV gene editing tools, custom cell line generation services for research and bioproduction applications, quantitative molecular reference standards, in vivo disease models, contract research and custom screening services and custom shRNA development services and off-the-shelf validated shRNA (through Horizon's partner Sirion).

Horizon is headquartered in Cambridge, UK, and is listed on the London Stock Exchange's AIM market under the ticker "HZD", for further information please visit: www.horizondiscovery.com.