Powering the Therapeutic Ecosystem

Proactive Investors One2One Investor Forum 30 July 2020 | London

Terry Pizzie, Chief Executive Officer

Disclaimer

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This presentation shall not constitute an offer to sell or the solicitation of an offer to buy any securities, nor shall there be any sale of any securities in any state or jurisdiction in which such offer,solicitation or sale would be unlawful prior to registration or qualification under the securities laws of any such state or jurisdiction.

This presentation (together with any other statements or information that Horizon Discovery Group plc (the ‘Company’) may furnish to you) is confidential and may not be reproduced, forwardedto any person or published, in whole or in part. This presentation does not purport to contain all of the information that may be required to evaluate all of the factors that would be relevant to you(the “Recipient”) considering any potential transaction and any Recipient should conduct its own investigation and analysis. This presentation is for informational purposes and reference onlypursuant to the Recipient’s request and is not intended to be, and must not be, taken as the basis for a decision with respect to any possible transaction. Neither the Company nor any of itsaffiliates or representatives makes any representation or warranty, expressed or implied, as to the accuracy or completeness of this presentation or any of the information contained herein, orany other written or oral communication transmitted or made available to the Recipient or its affiliates or representatives. The Company and its affiliates or representatives expressly disclaim tothe fullest extent permitted by law any and all liability based, in whole or in part, on the information contained herein or any other written or oral communication transmitted or made available tothe Recipient or its affiliates or representatives, including, without limitation, with respect to errors therein or omissions therefrom. This presentation has not been approved by an authorisedperson in accordance with Section 21 of the Financial Services and Markets Act 2000.Various statements in this slide presentation concerning the future expectations of the Company, its plans and prospects, constitute forward-looking statements. Words such as “anticipate,”“believe,” “could,” “estimate,” “expect,” “intend,” “may,” “might,” “plan,” “potential,” “should,” “target,” “would” and other similar expressions that are predictions of or indicate future events andfuture trends are intended to identify forward-looking statements. Such statements are based on the current beliefs and assumptions of the management team of the Company and on theinformation currently available to the management team of the Company and are subject to change. The Company will not necessarily inform you of such changes. These forward-lookingstatements are subject to known and unknown risks, uncertainties, assumptions and other factors that could cause the Company’s actual results, performance or achievements to be materiallydifferent than any future results, performance or achievements expressed or implied by the forward-looking statements.

Actual results may differ materially from those indicated by these forward-looking statements as a result of various important factors, including the Company’s ability to obtain and maintainprofitability in the future; the Company’s focus on higher-growth business units and next-generation technology; the Company’s ability to maintain adequate revenue growth and manage suchgrowth; the Company’s ability to penetrate its existing customer base and attract new customers; the Company’s ability to automate, scale and digitize portions of its business; the Company’sability to introduce and market new tools and services and improve existing tools and services successfully; the Company’s ability to meet anticipated timing for the launch of new products andservices; competition from others using technology similar to the Company’s and others developing products for similar uses; the Company’s ability to develop new technologies such as baseediting into marketable products; market trends; potential fluctuations in foreign currency exchange rates; the rapidly evolving nature of the fields and markets the Company operates in; and theCompany’s ability to obtain or protect intellectual property rights related to its proprietary gene editing and modulation technology. Any forward-looking statements represent the Company’sviews only as of today and should not be relied upon as representing its views as of any subsequent date. The Company explicitly disclaims any obligation to update any forward-lookingstatements.

Except where otherwise indicated in this presentation, the information provided herein is based on matters as they exist at the date of preparation of this presentation and not as of any futuredate. All information presented or contained in this presentation is subject to updating, revision, correction, verification, completion and amendment without notice. Any opinions expressed inthis presentation are subject to change without notice. Neither the Company nor any of its directors, officers, partners, employees, advisers, affiliates or agents is under any obligation toupdate, complete, revise or keep current the information contained in this presentation or to which it relates or to provide the recipient of it with any access to additional information that mayarise in connection with it. The presentation does not constitute an audit or due diligence review and should not be construed as such. This presentation has not been approved by anyregulatory or supervisory authority.

Horizon Discovery PLC

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High growth pure-play tools & services company

>2,000customers

• Decades of experience in cell engineering –our core competence

• Unique and high value portfolio of tools and services, which enable almost any gene to be altered, or its function modulated, in human and other mammalian cell lines

• Global customer base across the therapeutics value chain

• 2,000 customers in >60 countries as of 2019

• Sold to 19 of the 20 largest biopharma companies by revenue in 2019

• High growth business

• Revenues: FY 2019: £58.3m; HY 2020: £22.4m (impacted by Covid-19)

• 41% CAGR over last 5 years (2014 – 2019)

• Listed on AIM 2014

Manufacturing Headquarters:

Boulder, Co.United States

Headquarters:Cambridge,

England RegionalSupport:

Japan

400employees

85PHDs

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We believe our future growth will be driven by the following competitive strengthsInvestment highlights

Deep expertise in cell engineering Access to a variety of cell engineering technologies, which allows us to take a technology agnostic approach to delivering customer solutions

Portfolio with high growth potentialBusiness is underpinned by our Research Reagents business which generates over 50% of our revenues and supports the growth of Screening, BioProductionand Base Editing business units, all of which have high-growth potential

Market positionOur tools and services support and enable critical elements of the therapeutic ecosystem, from basic research through to drug discovery and development and therapeutic applications

Serving >2000 customers worldwideWe have established relationships with leading academic institutes and biopharmaceutical companies globally. Our 50-person sales organisation, comprising key account partners, territory sales and field application specialists, provides us with global reach, and is a key differentiator

Highly experienced management Our senior management team has a proven track record of growing successful global life science tools and services businesses and experience in industrialising, scaling and commercialising biological tools and services

Expertise Portfolio Market position Customers Management

Track record of revenue and margin growth

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• Strong growth in revenue and margin over last 5 years• Revenue: CAGR of 41%

• Gross Profit: CAGR of 44%

• Our strategy and market opportunity continues to support a high growth business

In December 2019, the Company completed its divestment of its non-core In Vivo business. These are excluded from the Company’s continuing operations reported above.

Our portfolio and its applications

Cells are the building blocks of life

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Cell behaviour is influenced by proteins

They have specialised functions and understanding how they work helps us understand, treat and prevent disease

Cells are the building blocks of life

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Gene editing impacts protein production in ways like a dimmer switch controls a light bulb on or off, brighter or dimmer

Geneediting

Understand disease

Understand drug mechanism

Transforming human health

Understand side effects

Cheaper, faster drug development

Precision medicine

Horizon is powering the therapeutic ecosystem

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The go-to provider of cell engineering solutions

Therapeutic Ecosystem

Tools designed to better understand drug-gene interactions and the genetic basis of disease

Basic Research

The need to improve the efficiency and efficacy of drug development. By factoring in genetics todrug development, researchers can improve the probability of success of clinical trials

Drug discovery & development

The development and production of new therapeutics or better therapeutic approaches, includingprecision medicines such as cell and gene therapies, and immuno-oncology

Therapeutic applications

Key

cha

lleng

es

We provide the technologies that allow researchers to either modulate (gene modulation) or permanently alter (gene editing) the functioning of genes

Supporting COVID-19 research

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Horizon’s gene editing toolkit is being used in many areas of scientific research and drug discovery

• ACE2 is a protein on the surface of many cells, acting as a protective barrier that plays a crucial role in the body

• Building on insights from the 2004 SARS outbreak, current research points to its importance for viral entry into cells

• The shape (spike) of the SARS-CoV-2 virus allows it to attach to ACE2, providing an entry point to infect human cells and stopping ACE2 doing its normal job

• Genetic factors (e.g. age, ethnicity, gender) affect levels of ACE2 in the body

• Horizon Discovery products and services help study these therapeutically relevant interactions between the virus and host, helping to understand the disease and accelerate the development of a potential treatment

Supporting COVID-19 research

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Nevan Krogan, Professor of Cellular Molecular Pharmacology at the University of California, San Francisco (UCSF)

• Works on infectious diseases and is part of a global collaboration of 22 laboratories based out of UCSF focused on fighting the COVID-19 pandemic

• The lab’s work maps how the virus hijacks host factors, with the aim of recycling FDA-approved drugs that could become effective treatments, and in the longer term to identify new drug targets

“Horizon’s ability to be quick and flexible meeting our CRISPR and siRNA needs has been instrumental in the

rapid progression of our COVID work.

“This partnership highlights the importance of academic and commercial collaborations when meeting public

health challenges posed by novel pathogens.

“We believe it's imperative to maintain this momentum beyond COVID, and it's encouraging to see that Horizon

Discovery is committed to the same."

An understanding of genetics can improve the speed and efficiency of the drug discovery process

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Meeting the challenge of drug development

Drug development is a long and expensive

process, the mantra in the industry is ‘fail early, fail fast’; the drug that makes it through to market has to cover these costs before

making money

What Horizon brings to the table is a technique

called CRISPR Screening which allows for a genetic component to be introduced during the drug development

process

Gaining knowledge about a drug in a genetic

context only at clinical trial is an expensive risk

A challenge is that we are all genetically

different, so our reaction to a drug might be

different, hence the need for comprehensive

clinical trials

An everyday story of CRISPR Screening

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CRISPR Screening has helped find new treatments for box jellyfish venom

• Researchers at University of Sydney, Australia set out to understand more about how this lethal venom works

• Carried out a Pooled CRISPR Screen, basically introducing the venom to a pool of genetically different cells to observe which cells survived

• By understanding the genetic differences of those impacted by the venom they worked out that the cholesterol pathway had been impacted by the venom

• This led to a potential drug which if re-formulated could treat those who were stung, until now a potentially lethal situation

CRISPR Screening can be used throughout the drug discovery to

process to understand how diseases work, what drug might be useful to treatment them, and how different

genetic traits might prevent a drug working or make it harmful

CRISPR Screening improves understanding by putting a genetic context into drug development leading to better drugs,delivered faster and more cost-effectively

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Application: CRISPR Screening

1. King et al., 2019 2. Nelson et al., 2015.

Despite strong vetting, only 10% of novel drug compounds in early stage clinical trials are eventually approved1, Drug targets with human genetic evidence of disease association are twice as likely to lead to approved drugs2

Disease Understand the disease

Select potential

drug candidates

Filter out problematic candidates

Select appropriate clinical trial

cohort

CRISPRscreening

CRISPRscreening

CRISPRscreening

CRISPRscreening

Historically, improving the production of biologics has focused on improving both upstream and downstream processing and not on improving the performance of the host cell line

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Application: manufacture of biologic drugs

Cell Lines Media and Feed$2B

Controllers & Bioreactors$1B

Purification$20B

Source: Market And Markets Reports “Downstream Processing Marker – Forecast to 2021” and “Cell Line Development Market – Forecast to 2019”

CHO Cells been used since 1957, last major

change to cell in 2010

Horizon is focused on developing gene edited cell lines to an industry seeking greater flexibility, increasedspeed to market and cost reduction

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Application: manufacture of biologic drugs

Cell Lines Media and Feed$2B

Controllers & Bioreactors$1B

Purification$20B

Source: Market And Markets Reports “Downstream Processing Marker – Forecast to 2021” and “Cell Line Development Market – Forecast to 2019”

Base editing can be used to engineer cell therapy including the development of next generation allogeneic Car-T therapies

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Application: Base editing for cell therapy

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Healthy Donor

Naive

Patients

YY

Y

YY

Y

YY

Y

T Cell

T Cell reprogrammed to recognise cancer cells

T Cell engineered to be compatible with patient using base

editing

T Cell recognises and destroys cancer cell

Stealth

Cancer CellThe cell becomes the drug and the same cell

can be used to target many cancers

Weaponised

Base Editing: Current developments

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“Horizon has sought input from AstraZeneca, a long-term partner for CRISPR-based products and services, to expedite

development of the technology

“AstraZeneca has been exploring base editors as potential therapeutic tools

“We’ve made a lot of progress with base editors in the past few months, we have a very good relationship with AstraZeneca, and we’re confident that their broad knowledge in genome editing is really going to help catapult forwards what we’re

doing with base editing.”

https://pages.pharmaintelligence.informa.com/horizon-base-editing-download

Ben Taylor, Discovery Biology,Discovery Sciences, R&D,AstraZeneca

Dr Ceri Wiggins R&D Manager

Horizon Discovery

BASE EDITING: An Innovative Player DrivingCell And Gene Therapy To New Frontiers• The Horizon gene editing story continues to

evolve with the development of base editing

• Since 2010 Horizon has invested in developing therapeutic gene editing technologies for our customers

• The company is preparing to launch a licensing program enabling companies in the cell and gene therapy fields

• As part of this exciting development Horizon is actively engaged with key opinion leaders and pharmaceutical partners

Horizon’s portfolio and market opportunity

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CAR-T therapy $3.14bn 2020

Gene therapy$3.8bn 2019

$1bn$2.3bn

by 2022

BioProduction

An established player with more than 80 license engagements, providing biopharma and CMOs with an engineered CHO cell line to enable efficient manufacture of biologics

Base Editing

Recently established to develop and commercialize a novel gene editing platform as an alternative to CRISPR to accelerate therapeutic developments. Exclusive license from Rutgers for use in all therapeutic applications.

CAR-T therapy $3.14bn 2020

Gene therapy$3.8bn 2019

$1bn$2.3bn

by 2022

$3bn~12% CAGR through 2024

$8bnrising to

$12bn by 2023

Research Reagents

A market leader in the supply of RNAi gene modulation and CRISPR gene editing reagents, cell line engineering (both custom made and OTS cell lines) and diagnostic reference standards

Screening

A market leader in CRISPR screening used by biopharma companies to find novel drug targets, identify mechanisms of drug resistance, repurpose therapeutics for new indications and stratify patients for clinical trials

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HORIZON DISCOVERY

HY 2020 Results Unaudited

Financial highlights: HY 2020 (unaudited)

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1 – In December 2019, the Company completed its divestment of its non-core In Vivo business. These are excluded from the Company’s continuing operations reported above.

£22.4m-13.9%

HY 2019:£26.1m1

66.0%HY 2019:71.2%1

£(4.6m)HY 2019:£(0.0m)1

£23.6mHY 2019:£24.8m

Revenue• Reduction largely

due to COVID-19 as academic research reduced during lockdown

• Sustained recovery since low point in April

Cash• Prudent cash

management and a Placing of £6.9m gross ensures significant cash headroom

Gross margin• Reduced due to

impact of COVID-19 on manufacturing costs and additional stock provisions

Adjusted EBITDA• Impacted by

reduction in revenue

Summary

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• Thanks to the dedication and professionalism of our team, we have continued to operate effectively throughout the crisis

• We have supported our customers as they have turned to outsourcing as a solution to their own business challenges during the pandemic and as a consequence, our relationships with them have become deeper and stronger

• We expect the trend for increased outsourcing to continue and for these relationships to endure beyond the crisis. This high-level access within our biopharma customer base that will help lay the foundations for commercialising our new high growth areas

• We remain focused on executing the Group’s strategy and are excited about the continued expansion of our screening market and commercialising our investments in BioProduction and Base Editing

• The fundamental drivers for our products and services remains strong and we are confident of a return to growth in H2 2020

For further information

Horizon Discovery Group plcTerry Pizzie, Chief Executive OfficerJayesh Pankhania, Chief Financial OfficerJon Davies, Head of Investor RelationsTel: +44 (0) 1223 655 580www.horizondiscovryplc.com

Westwicke, an ICR Company(US Investor Relations)Stephanie CarringtonTel. +1 646-277-1282Email: horizondiscovery@icrinc.com

Numis Securities Limited(Broker and NOMAD)Freddie Barnfield / Duncan MonteithTel: +44 (0) 207 260 1000

Consilium Strategic Communications(Financial Media and UK Investor Relations)Mary-Jane Elliott / Matthew Neal / Melissa GardinerTel: +44 (0) 20 3709 5700Email: horizon@consilium-comms.com