Full Year Results Deferral and COVID-19 Update

Horizon Discovery Group plc

FCA Temporary Moratorium on Release of Full Year Results by All Public Companies and COVID-19 Update

Cambridge, UK, 27 March 2020: Horizon Discovery Group plc (LSE: HZD) ("Horizon" "the Group" or "the Company"), a cell engineering company focused on commercializing the application of gene editing and gene modulation to accelerate scientific innovation and biopharmaceutical drug development, today announces that it will follow the request from the Financial Conduct Authority ("FCA") for all public companies to delay the publication of Preliminary Results for at least two weeks from 21 March 2020 and defer the announcement of its audited Full Year 2019 Results. Horizon had intended to publish audited Full Year Results on 30 March 2020.

The Company will notify the market with a new date for when it intends to publish its audited Full Year 2019 Results, in due course.

COVID-19 update

Events in relation to the COVID-19 pandemic continue to evolve rapidly and the Group is monitoring the situation closely. Horizon's first priority remains the health and safety of its employees and visitors to its sites. The Group has actioned business continuity plans aimed at safeguarding its employees and their dependents while maintaining Horizon's inventory, manufacturing, production and service capacity.

As part of Horizon's business continuity plans, the Company invested in an IT infrastructure that enables effective remote working when needed. Horizon's experienced laboratory teams can work flexibly, facilitating different working patterns that will both minimize the impact of COVID-19 and meet the Group's duty of care to its employees.

Horizon has moved into 2020 with a simplified, more robust and focused business. As a high-growth Group comprising a mix of well-established and potentially disruptive business units, Horizon has not yet seen any material impact to the business from COVID-19. The Group has put in place contingency measures to support any additional changes that might be necessitated by the fluidity of the current situation. Furthermore, at this point in time, Horizon is not currently experiencing any delays in either distributing its products or running its service projects and, in the UK and US, governmental authorities have confirmed that both operations are essential industries1,2 as are many of the Group's customers. Therefore, Horizon expects to remain fully operational during this time.

Given the rapid evolution of the situation, the Group is unable to predict the full year consequences of the coronavirus pandemic. Horizon continues to have a strong, forward looking order book and started the year with £18.8m of cash. The Group is reviewing the potential impacts of coronavirus and evaluating options to conserve cash. Horizon believes that these measures and the Group's existing cash balance provides the Company with a significant runway to weather a downturn.

References

1US, Dharmacon operations in Boulder: Boulder County guidelines on Healthcare Operations during COVID lockdown (Boulder County Public Health: Stay at Home Order, 25 March: https://www.bouldercounty.org/families/disease/covid-19/stay-at-home-order/#healthcare-operations)

2UK: Government guidance on key workers in Health and Social Care (Gov.UK: Guidance for schools, childcare providers, colleges and local authorities in England on maintaining educational provision, 19 March: https://www.gov.uk/government/publications/coronavirus-covid-19-maintaining-educational-provision/guidance-for-schools-colleges-and-local-authorities-on-maintaining-educational-provision)

Ends

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

Horizon Discovery Group plc

Terry Pizzie, Chief Executive Officer

Jayesh Pankhania, Chief Financial Officer

Jon Davies, Head of Investor Relations

Tel: +44 (0) 1223 655 580

Numis Securities Limited (Broker and NOMAD)

Freddie Barnfield / Duncan Monteith

Tel: +44 (0) 207 260 1000

Consilium Strategic Communications (Financial Media and Investor Relations)

Mary-Jane Elliott / Matthew Neal / Melissa Gardiner

Tel: +44 (0) 20 3709 5700

Email: [email protected]

Westwicke, an ICR Company (US Investor Relations)

Stephanie Carrington

Tel. +1 646-277-1282

Email: [email protected]

About Horizon Discovery Group plc www.horizondiscovery.com

Horizon Discovery Group plc (LSE: HZD) ("Horizon") is a cell engineering company focused on commercializing the application of gene editing and gene modulation to accelerate scientific innovation and biopharmaceutical drug development. Horizon's portfolio of tools and services is built on decades of experience in altering the expression of genes across mammalian and human cell types to provide cell engineering tools and services to customers in three key areas of the therapeutic ecosystem: basic research, drug discovery and development and therapeutic applications. Horizon's offerings support and enable critical elements of the drug development and therapeutic value chain, particularly in the area of precision medicine. Horizon's customers include biopharmaceutical and diagnostics companies, contract research and manufacturing organizations and academic researchers across the globe.

Horizon is headquartered in Cambridge, UK with offices in USA and Japan. The Group is listed on the London Stock Exchange's AIM market under the ticker HZD.