Building aGlobal Leader in

Orphan Oncology

June 2017

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Important Information

June 2017

IMPORTANT: You must read the following before continuing. In accessing this document, you agree to be bound by the following terms and conditions.

This document has been prepared by Onxeo SA (together with its subsidiaries, the "Group") and is for information purposes only. The content of this document is provisional andfor information purposes only and is not to be construed as providing investment advice. The information, statements and opinions contained in this document (the“Information”) are provided as of the date of this document only and may be subject to significant changes at any time without notice. Neither the Group, nor its advisors, nor anyother person is under any obligation to update the Information. Subject to applicable law, none of the Company or its advisors accepts any responsibility whatsoever and makesno representation or warranty, express or implied, as to the fairness, accuracy, completeness or correctness of the Information. The Information has not been subject toindependent verification and is qualified in its entirety by the business, financial and other information that the Group is required to publish in accordance with the rules,regulations and practices applicable to companies listed on Euronext Paris, including in particular the risk factors in the Company’s Registration Document filed with the FrenchFinancial Markets Authority (Autorité des marchés financiers) under number D.17-0423 on April 24, 2017, in any other periodic report and in any other press release, which areavailable free of charge on the websites of the Group (www.onxeo.com) and/or the AMF (www.amf-france.org).

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A publicly-traded biotech company specialized in orphan oncology

Developing innovative drugs to address unmet medical needs in Oncology

Based in Paris, Copenhagen and New York; listed on Euronext (Paris) and Nasdaq (Copenhagen)

A solid, diversified and well-balanced pipeline

Livatag®: Currently in Phase III for Hepatocellular Carcinoma (HCC)

Beleodaq®: Marketed in the US by Spectrum for 2nd line Peripheral T-Cell Lymphoma (PTCL)

AsiDNA™: 1st-in-class DNA Repair Signal Interfering with compelling Phase I data

…with significant sales potential

Livatag®: HCC estimated incidents 480,000 patients WW(1)

Beleodaq®: Potential Market Size from € 7.9 B in 2016 to € 19.3 B in 2025(2)

AsiDNA™: Potential Market Size up to € 2.1 B by 2025 just for the first pre-identified indication(3)

... and potentially value-creating near & mid-term milestones

Cash position expected to support currently planned operations until early 2018

Investment Thesis

(1) Internal estimate (2) Source GlobalData &Navigant for NSCLC +SCCHN+ PTCL indications(3) SourceGlobaData for TNBC indication

June 2017

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Onxeo’s laser-focused strategy

Crafting a solid and diversified orphan oncology pipeline

Active M&A strategy to enrich and diversify the pipeline

with innovative, first-in-class compounds

Bring innovation to orphan oncology patients

Create shareholder value througha proven business model

Develop products into clinical up to key inflexion points, attractive to pharmaceutical key players

Experienced team with demonstrated leadership

3 products already approved by FDA and/or EMA

Unparalleled skills from preclinical & CMC to Phase III

June 2017

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A complementary and experienced management team…

NICOLAS FELLMAN | CFO

Formerly Pfizer, Ernst & Young

FRANÇOISE BONO | PhD, CSO

Sanofi, Evotec

Evotec’s EVP until 2016

OLIVIER DE BEAUMONT | MD, CMO

Formerly Senior VP StallergenesGreer, Quintiles, Aventis

PHILIPPE MAITRE | EVP Onxeo Inc., CBDO

Leads the US subsidiary

Formerly Aventis, PPD, mAbRx

JUDITH GRECIET | Pharm.D, CEO

Formerly Wyeth, Eisai

Eisai France President until 2011

June 2017

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…advised by an international board of industry experts

JOSEPH ZAKRZEWSKIChairman of the Board

JUDITH GRECIETCEO

DANIÈLE GUYOT-CAPARROSIndependent director

CHRISTINE GARNIERIndependent director

JEAN-PIERRE BIZZARIIndependent director

THOMAS HOFSTAETTERIndependent director

JEAN-PIERRE KINETIndependent director

NICOLAS TREBOUTA Director, representingFinancière de la Montagne

ELVIRA SANZIndependent director

June 2017

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A diversified and well-balanced portfolio in orphan oncology

June 2017

Livatag® Update

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Livatag® mechanism of action optimal for liver cancer

Nanoparticle formulation of doxorubicin

Proprietary Transdrug™ nanotechnology platform

Nanoformulation designed to evade tumor cell resistance mediated by Multi Drug Resistance (MDR) efflux pumps

– Up to 12-fold increased exposure to liver tumor cells compared to doxorubicin

Mechanism of action

Absorption to the cell surface

Release of doxorubicin close to the cell membrane as ion pair doxo/PEBCA(*)

Ion pair protects doxorubicin - reduced drug efflux through MDR-related protein

Increased nuclear delivery of free doxorubicin with subsequent cytotoxic effect

(*) PEBCA polymer = Poly-Ethyl-Butyl-CyanoacrylateJune 2017

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Designed to confirm promising Phase II efficacy results

n=28 Patients with unresectable HCC

Multicenter, controlled and randomized trial; up to 3 injections per week over 4 weeks

Median survival of 31.7 months vs. 15 months for patients on TACE (p < 0.05)

Acute respiratory adverse events leading to study termination and change of administration scheme in phase III

Phase III Study to assess efficacy (OS) and safety of Livatag® (20 and 30mg/m² - slow IV) vs Best Standard of Care after failure or intolerance to sorafenib

A favorable safety profile confirmed by Data Safety Monitoring Board (DSMB) reviews

10 consecutive DSMB reviews: positive recommendations to continue study w/o modification

No apparent pulmonary toxicity after more than 1000 infusions, no unexpected AE.

Preliminary results available before end of September 2017

Livatag® “ReLive” Phase III Pivotal Study

June 2017

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Livatag: ReLive Phase III Study - design

PHASE III

Randomized, comparative, 3 arms

390 patients (>= 18 years old)

11 countriesEU, US, MENA

70 active centers

6-hour IV infusion -20 mg/m²

n =130Best standard of care

n =130 <4 weeks>

n =130

< 4 weeks>

Preliminary resultsoverall survival

after 285 events

6-hour IV infusion - 30 mg/m²

< 4 weeks> < 4 weeks>< 4 weeks> … up to progression

< 4 weeks> < 4 weeks>< 4 weeks>

End of randomization

Jan 2017

Before end of Sept 2017

TARGET POPULATION

2nd line or more advanced HCC having progressed or intolerant to sorafenib, stage BCLC B or C with a Child-Pugh score from A5 to B7

ENDPOINTSPrimary endpoint: Overall Survival

Secondary endpoints: Progression Free Survival, Objective Response Rate, Optimal dose, Safety, PK, Predictive factors of safety and efficacy, Quality of life

… up to progression

June 2017

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In the large but under-served HCC market

Only one product approved (Sorafenib) in first line HCC

Estimated incidence of 120,000(1) eligible patients (US + Europe); 480,000(1) patients WW

Company will initiate Licensing discussions after Phase III results

Potential to explore Livatag full potential for HCC …

Targeting HCC 1st-line in combination with Tyrosine Kinase inhibitors

Livatag ®, a potential blockbuster

(1) internal estimateJune 2017

belinostat / Beleodaq®Update

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Beleodaq® (IV belinostat) approved as 2nd line treatment for PTCL

Peripheral T-cell lymphoma (PTCL)

Subtype of non-Hodgkin’s lymphoma (NHL) which affects T-cells

Worldwide incidence = 38,000 to 58,000 cases(1) (10-15% of NHL cases) / 17,000 to 27,000 incident cases(1) in key pharmaceutical markets (US + EU28 + Japan + China)

FDA conditional approval in 2nd line PTCL following successful Phase II (Belief Study: n = 129)(2)

25.8 % ORR (CR&PR) - Median DoR of 13.6 months by IWG criteria (to disease progression)

Low incidence of Grade 3-4 hematologic toxicities (thrombocytopenia 7%; neutropenia 6.2%; anemia 10.9%)

Phase I Bel-CHOP combination performed to assess MTD and safety profile (n=23) in 1st Line PTCL

Belinostat MTD is 1000mg/m2 days 1-5 every 3 weeks + CHOP = approved doses

ORR 86%; CR 67% (CR CHOP ~50%), PR 19%

Phase III synopsis in PTCL 1st line under preparation with Spectrum Pharma

(1) International Peripheral T-Cell and Natural Killer/T-Cell Lymphoma Study , (J Clin Oncol 26 :4124-4130) and GLOBOCAN 2012, IARC data.

(2) Lee et al (FDA approval) Clin. Cancer Res. March 2015.June 2017

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Expand PTCL beyond the US (Europe – South America - ….)

Commercialized in the US by Spectrum since July 2014

Expansion to South America through licensing agreement with Pint Pharma

Patient early access program launched in Europe (PTCL)

Development of an oral formulation of Beleodaq® to expand product potential in particular for combination with immune checkpoint therapies

An important step providing opportunities for new indications & extended patent protection

Exploratory preclinical research program in combination with other anti-cancer agents

Follow-up studies ongoing to assess combination interest in various tumors, to enter clinic by year-end

Market for potential indications (IV and Oral forms combined): estimated at € 7.9 B in 2016 and € 19.3 B in 2025 (1)

belinostat / Beleodaq®: Build value potential beyond PTCL

(1) Source GlobalData and Navigant for NSCLC +SCCHN+ PTCL indicationsJune 2017

AsiDNATM

An Innovative Concept Leadingto a First-in-Class Product

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AsiDNATM concept: leading tumor cells to death through the blinding of the DNA repair system

1

2

3

Multiple DNA repair pathways are activated in

cancer cells via the recruitment of

several enzymes allowing them to repair efficiently

damaged DNA and escape cell death

AsiDNA mimics DNA breaks into the cells and activates DNA damage signaling enzymes, thus inducing a “false” damage signal that

prevents the repair enzymes from being recruited at the site where they should act to repair the damage on the tumor cell’s chromosomes

Cancer cells are no longer able to continue dividing with damaged DNA, resulting in cell death

Why DNA repair inhibition?▪ Many cancer treatments rely on DNA damaging agents

▪ Tumor cells survive genotoxic treatment by repairing DNA damage

▪ DNA repair is a main mechanism of resistance to radiotherapy and chemotherapy for advanced stagetumors (exposition to DNA damage and replication accidents that need to be repaired)

June 2017

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5’

3’

3’

5’

1. Quanz M, et al. PLoS ONE. 2009 4(7), doi: 10.1371/journal.pone.0006298 2. Berthault N, et al. Cancer Gene Therapy (2011), 1-12, doi: 10.1038/cgt.2011.3

AsiDNA™ - A first-in-class molecule

Double-stranded 32 bp DNA is tethered with a loop to prevent disassociation1

Phosphorothioate substitutions at the 5’ and 3’ ends to prevent degradation1

Efficient nuclear uptake of the DNA is mediated via a covalently linked cholesterol molecule2

32 bp DNA duplex with a 5´-Chol-TEG & a non-nucleotidic loop - Protected from disassociation and degradation and designed for optimal cellular uptake

Cholesterol - Vector that promotes cellular uptake

Loop- Coupling Agent

Active 32 bp DNA duplex

AsiDNA – First of a new class of DNA repair inhibitors

Binds and activates DNA-PK and PARP signaling enzymes

Sequence not specific, chosen to be non-homologous

Genomic DNA length optimized

June 2017

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Synergistic effect of AsiDNA™ combined with various PARP inhibitors including oloparib(2)

Increased unrepaired DNA break sites, DNA damages and cell lethality in 21 different tumor cell lines including BRCA mutated

No lethality observed in healthy cells

Strong indication that drug resistance to the combination would be a very rare event

Preclinical in vivo efficacy of AsiDNA™ vs. PARP inhibitors in mouse triple negative breast cancer model(1) : potential as monotherapy in genetically unstable tumors

(1) Jdey W, et al. Cancer Res. 2017 Jun 6. pii: canres.2693.2016. doi: 10.1158/0008-5472.CAN-16-2693(2) Jdey W, et al. Clin Can Res. 2016;22:DOI: 10.1158/1078-0432.CCR-16-1193.

AsiDNA™- Solid synergy in combination with PARP inhibitors

June 2017

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AsiDNA™- First clinical outcome and development strategy

DRIIM phase I (2015)(1)

23 metastatic melanoma patients, 12 centers in France

AsiDNA™ in combination with radiotherapy, (3 doses/week for 2 weeks, intratumoral admin.)

Good tolerance, strong immune tolerance and no evidence of inflammatory phenomena

ORR = 59%; CR = 30%; PR = 29% ( CR rate from low-dose radiotherapy alone less than 10% (Konefal et al, 1987; Olivier et al, 2007)

Strong evidence supporting activity by systemic administration

Preclinical animal models

Observations from DRIIM Phase I

Mechanistic and predictive biomarkers available to support clinical development

Next step to demonstrate potential when dosed via intravenous route

Phase I in mono and combination in preparation (2017)

Broad spectrum of potential indications : e.g. market size estimate for TNBC from

€ 0.8 B in 2016 to €2.1 B by 2025 (2)

(1) Le Tourneau C, et al. BJC. 2016;1-7; doi:10.1038/bjc.2016.120.(2): Source GlobalDataJune 2017

IP & Financial Position

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Solid IP protection(*) for all products in the pipeline

Livatag®

Composition patent through 2019 with additional patents through 2032

US Patent on specific administration route protecting related claims until 2032

New patent filing on composition potentially protecting Livatag® WW until 2036

Orphan status in both Europe and US; Fast Track designation in US

Beleodaq®

Drug substance patent until 2021, drug product patent until 2027 (2026 o/US)

Orphan status in both EU & US - accelerated FDA approval July 2014for 2nd line PTCL

AsiDNA™

Proprietary technology (Method of Use) patent until 2024

Drug product and related compounds protected until 2031

(*) Not including potential supplementary protection certificate (SPC) or patent term extension (PTE).

June 2017

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Shareholder structure and financial profile

Shareholder structure (as of Feb. 28, 2017) Dual listing – ticker ONXEO

47M shares outstanding

Market capitalization €220M +/-(June 2017)

Cash position on 03/31/17: €21.7M

Expected cash runway to early 2018

June 2017

32%Institutional investors

54%Other free float

14%Financière de la Montagne

Upcoming Milestones

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2017 expected newsflow

June 2017

Livatag®

Beleodaq® Oral

June to Year-end 2017

Phase I/II initiation

Preclinical PoC of IV activity ( expected Q3 2017)

Phase I Initiation (Systemic administration)

AsiDNA™

Oral formulation preclinical results mono/ combo (expected Q3 2017)

ReLive Phase III trial preliminary results before end of September

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A differentiated biotech company in orphan oncology

A strong & diversified

product portfolioTargeting significant

unmet medical needs

Focused on indications with large

market potential

A proactive, experienced global team

June 2017

Contacts:Judith Greciet – CEONicolas Fellmann – CFOTel: +33 1 45 58 76 00 -contact@onxeo.com

Company Information:www.onxeo.com