Progress Update: Molecular Screening Platform

Horizon Discovery Announces a Progress Update on its

High-throughput Molecular Screening Platform

· Over £800,000 of new drug combination and immuno-oncology service agreements signed

· FY16 molecular screening order book exceeds current operational capacity

· FY17 molecular screening order book in excess of £1.6 million

Cambridge, UK, 1 November 2016: Horizon Discovery Group plc (LSE: HZD) ("Horizon"), the world leader in the application of gene editing technologies, today provides an update on the operation of its high-throughput molecular screening platform, which includes drug combination and immuno-oncology screening. Horizon announces the signing of more than £800,000 of new drug combination and immuno-oncology service agreements with revenue to be recognised in Q4 2016 and early 2017.

The Group notes that available high-throughput molecular screening capacity is now full for FY16 and in excess of £1.6 million of further agreements are now in place, to be recognised in FY17. In addition, significant additional work from these partners is anticipated following initial smaller pilot screens or as the start of a broader programme of drug combination screens, which could result in a further over £1 million in new molecular screening revenues in FY17.

The projects announced today include a sizeable drug combination study from a previous long-term top five pharma partner with a long history of working with Horizon for drug combination screening, and additional agreements with multiple top twenty pharmaceutical and emerging biotech companies. Each project varies in size and scope, from small screens involving a limited number of cell lines to far more complex work packages for testing highly promising novel compounds against large panels of cell lines. Individual molecular screening contracts vary from £40k to £400k and operate for between 1-4 months.

Dr. Darrin Disley, Chief Executive Officer, Horizon Discovery, commented: "Today's announcement clearly demonstrates that our high-throughput molecular screening business is strong. As was recently announced, Horizon has taken the step to consolidate all screening operations from Boston, USA to Cambridge, UK. By doing so we have not only reduced our cost base but have also established a more efficient and integrated Services business platform, providing an engine for growth for a broad range of applications and markets. With a robust pipeline running at full capacity for the remainder of 2016 and building momentum for a strong Q1 and full year 2017, molecular screening remains a core driver of Horizon's Services business and we look forward to the future with confidence."

ENDS

About Horizon's High-throughput Molecular Screening platform:

Combination therapies have become the standard of care in many diseases including oncology, with immuno-oncology emerging as an area of particular promise. It is widely accepted that the biological pathways fundamental in many serious diseases are highly complex with individual cell types containing a unique network of pathways and, as a result, traditional monotherapies are often insufficient.

It is important therefore to assess these drug or compound combinations to look for synergistic or antagonistic effects as they will directly impact patient care. These may be observed either as an increase in the anti-proliferative or cell killing effect, or as potency shift such that lower dosages are required to see the same therapeutic effect.

Horizon is recognised as a leader in high-throughput molecular screening, with over a decade of experience analysing over 10 million unique drug combinations. Horizon's core platform technology in this area is used to profile compounds at high throughput as single agents or combinations across hundreds of well annotated cancer cell lines in order to discover new combination therapies, to aid patient stratification, and to gain actionable insights in a short period of time.

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

Horizon Discovery Group plc

Darrin Disley, Chief Executive Officer

Richard Vellacott, Chief Financial Officer

Chris Claxton, VP Investor Relations

Tel: +44 (0) 1223 655 580

Consilium Strategic Communications (Financial Media and Investor Relations)

Mary-Jane Elliott / Susan Stuart / Matthew Neal / Melissa Gardiner

Tel: +44 (0) 20 3709 5701

Email: [email protected]

Zyme Communications (Trade and Regional Media)

Katie Odgaard

Tel: +44 (0)7787 502 947

Email: [email protected]

Numis Securities Limited (Joint Broker and NOMAD)

Michael Meade / Freddie Barnfield

Tel: +44 (0) 207 260 1000

RBC Capital Markets (Joint Broker)

Paul Tomasic / Marcus Jackson

Tel: +44 (0) 20 7653 4000

About Horizon Discovery Group plc www.horizondiscovery.com

Horizon Discovery Group plc (LSE: HZD) ("Horizon"), is a world-leading gene editing company that designs and engineers genetically-modified cells and then applies them in research and clinical applications that advance human health.

Horizon's core capabilities are built around its proprietary translational genomics platform, a highly precise and flexible suite of gene editing tools (rAAV, ZFN and CRISPR) able to alter almost any gene sequence in human or mammalian cell-lines.

Horizon offers over 23,000 catalogue products and related research services, almost all of which are based on the generation and application of cell and animal models that accurately recapitulate the disease-causing genetic anomalies found in diseases like cancer. Horizon's commercial offering has been adopted by c. 1,600 unique research organisations in over 50 countries as well as in the Company's own R&D pipeline to support a greater understanding of the genetic drivers of disease and the development of molecular, cell and gene therapies that can be prescribed on a personalised basis.

Horizon is headquartered in Cambridge, UK, and is listed on the London Stock Exchange's AIM market under the ticker "HZD".