A SIGNIFICANT PLAYER

IN ACTIVATION AND REGULATION

IMMUNOTHERAPIES

OCTOBER 2016

October 2016

DISCLAIMER / IMPORTANT NOTICE2

Forward-looking statements

This presentation contains express or implied information and statements that might be deemed forward-looking information and statements in respect of OSEImmunotherapeutics. They do not constitute historical facts. These information and statements include financial projections that are based upon certainassumptions and assessments made by OSE Immunotherapeutic’s management in light of its experience and its perception of historical trends, current economicand industry conditions, expected future developments and other factors they believe to be appropriate.

These forward-looking statements include statements typically using conditional and containing verbs such as “expect”, “anticipate”, “believe”, “target”, “plan”,or “estimate”, their declensions and conjugations and words of similar import.

Although the OSE Immunotherapeutic’s management believes that the forward-looking statements and information are reasonable, the OSEImmunotherapeutic’s shareholders and other investors are cautioned that the completion of such expectations is by nature subject to various risks,known or not, and uncertainties which are difficult to predict and generally beyond the control of OSE Immunotherapeutics. These risks could causeactual results and developments to differ materially from those expressed in or implied or projected by the forward-looking statements. These risks includethose discussed or identified in the public filings made by OSE Immunotherapeutics with the AMF. Such forward-looking statements are not guarantees of futureperformance.

This presentation includes only summary information and should be read with the OSE Immunotherapeutics Reference Document filed with the AMF on 8 June2016 under the number R.15-052, the consolidated financial statements and the management report for the fiscal year 2015, as well as the Merger Documentregistered with the AMF on 26 April 2016 under number E.16-026, all available on the OSE Immunotherapeutic’s website.

Other than as required by applicable law, OSE Immunotherapeutics issues this presentation at the date hereof and does not undertake any obligation to updateor revise the forward-looking information or statements.

DELIVERING FIRST-IN-CLASS IMMUNOTHERAPIES3

Core expertise: targeting the drivers of pathologies caused by failure in immune activation or regulation

Tedopi®

Effi-DEM

Immune activation and regulation

OSE IMMUNOTHERAPEUTICS: A LEADER IN IMMUNE ACTIVATION AND REGULATION

Creating a world-leader in immunotherapy based on immune system activation and regulation

Developing first-in-class immunotherapies with blockbuster potential in immuno-oncology, autoimmune diseases and transplantation

Balanced portfolio with diversified risk profile:

• Lead immuno-oncology activation product Tedopi® in a Phase 3 registration study/NSCLC

Combination with checkpoint inhibitor: Tedopi® Phase 2 planned

• New generation checkpoint inhibitor targeting SIRP-α on strategic pathway CD47/SIRP-α:Effi-DEM in preclinical development

• Lead immune regulation candidate: FR104 licensed to J&J, Phase 2 status

• Effi-7 in preclinical /inflammatory bowel diseases and other autoimmune diseases

Scale, capability and expertise to secure strategic industry partnerships

Experienced international team and network of experts in immunotherapy

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BALANCED AND DIVERSIFIED PORTFOLIO OF INNOVATIVE DRUG CANDIDATES5

Tedopi®Lung Cancer (NSCLC)

HLA-A2+ patients Phase 3 EU-USA

Phase 2 status

Phase 2 status

Tedopi®Combination with CKI* (NSCLC)

HLA-A2+ patients

FR104**Autoimmune diseases,

Transplantation

Effi-7***Autoimmune diseases

IL-7

Effi-DEMImmuno-oncology

New Checkpoint InhibitorSIRP-α on CD47/ SIRP-α

**Licensed to

Preclinical ***Co-financed by OSE Immunotherapeutics, leader of the EFFIMab consortium, Bpifrance

Preclinical

*Considered in 2017

Patient recruitment ongoingExpected registration: 2019

OUR TARGETED DISEASES & MARKETS IN IMMUNO-ONCOLOGY AND

AUTOIMMUNE DISEASES

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Immuno-Oncology:

• Objectives: leverage of the brakes on the immune system and / or activation of cells able to attack and kill cancer cells

• Potential sales of $67 billion a year over the next 10 years and may be used in some way in the management of up to 60 percent of all cancers*

Autoimmune diseases:

Rheumatoid Arthritis, Inflammatory Bowel Diseases IBD (Crohn Disease and ulcerative colitis), Psoriatic arthritis, Psoriatic plaques, Multiple Sclerosis (over a thousand known)

Objective: Restore the immune regulation

Primary cause of disability in young adults, strong need for treatments and public health issue

Breakthrough products in the same indications, examples**:

Global sales 2014: Humira® 14$B, Remicade® 10$B, Enbrel® 9$B, Prograf® 2.2$B

*BCC research2015**GlobalData's pharmaceutical revenue figures

A STRONG POTENTIAL OF GLOBAL MARKET FOR TEDOPI®: ESTIMATED PEAK

SALES OF OVER €2B7

Global Estimated Sales: > €2B - EU: €1B; USA: €760M; Japan: €280M; China: €200M

Completion of registration Ph 3

Non-Small Cell Lung cancer 1.4 M new cases worldwide/yearHLA-2+ = 45% of NSCLC population

TEDOPI® in NSCLC in 2nd or 3rd line treatment

Registration Europe/USLaunch US

Launch Europe

2018 2019 2020

TEDOPI®: A SPECIFIC T ACTIVATION IMMUNOTHERAPY IN ONCOLOGY8

Technology: Optimization of epitopes to increase the binding to the HLA-A2 and TCR receptors• « Neo-epitopes » optimized and combined to activate a cytotoxic T-cell response able to destroy cancer cells

they recognize (T specific response) – Combination of neo-epitopes: technology named Memopi®Epitopes : Small peptides, first T lymphocyte activation signal, selected from various tumor antigensfighting heterogeneity of cancer

• Tedopi® proprietary combination of 10 optimized « neo-epitopes » (selected from 5 tumor-associated antigens expressed in various cancers)

• Restores the immunosurveillance of cancer cells in HLA-A2 positive responder patients• Induces early T cell memory responses with short peptides HLA-A2/ TCR binding properties combination

Neo-epitopes affinity to the MHC (as HLA-A2) and neo-epitopes affinity to TCR represent a double sided key to activate T cell immune response* =T cytotoxic cells

*Fritsch EF et al- Cancer immunology Research 2014

TEDOPI® PHASE 2 RESULTS 64 NSCLC STAGE IIIB & IV AFTER AT LEAST FIRST LINE FAILURE: LONG TERM SURVIVAL

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1st injection 4 year survival: 25%*

* Survival in the literature is at 1% for stage IV NSCLC

SURVIVING PATIENTS FOLLOWING 2 YEAR TREATMENT WITH TEDOPI®

67% of the patients enrolled in the Phase 2 study were metastatic

65.5% received more than 2 previous lines of treatment

9% of Brain Metastasis patients

25%

PROMISING CLINICAL RESULTS IN THIS DIFFICULT PATIENT POPULATION

STRONG IMPROVEMENT IN THE LONG TERM SURVIVAL RATE IN PATIENTS WITH POOR PROGNOSIS FACTOR*

MEDIAN OVERALL SURVIVAL: 17 MONTHS

TEDOPI® PHASE 2 RESULTS: LONGER TIME TO PROGRESSION (TTP)CORRELATION BETWEEN IMMUNE RESPONSES AND SURVIVAL

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Kaplan – Meier Estimate of TTP

TIME TO PROGRESSION: MEDIAN AT 9.4 MONTHS

CORRELATION BETWEEN EPITOPES RESPONSES AND SURVIVAL (p<0.001)

4 to 5 epitopes: 875 ± 67 days of survivalHigh

Medium

Low

2 to 3 epitopes: 778 ± 72 days of survival

0 -1 epitope: 406 ± 58 days of survival

High CTL immune responses and survival

91% positive responses to 1 or more epitopes:64% positive to at least 3 epitopes

Source: M. Barve et al; J Clin Oncol 26: 2008 (May 20 suppl; abstr 8057); M Barves JCO 2008; Janus, Lung Cancer

review 2012- J. Nemunaitis, abstr 1202 brain metastasis WORLD CONFERENCE ON LUNG CANCER 2015

TEDOPI® IN PHASE 3 REGISTRATION TRIAL11

Dec 2015 : Scale up and GMP manufacturing achieved and 70 EU/US selected Jan 2016: Study initiated Europe/USA:

Randomized, multicenter, population of 500 patients,HLA-A2+, with invasive or metastatic Non-Small Cell Lung Cancer (NSCLC)

Versus chemotherapy (docetaxel/pemetrexed)Second line or third line treatment (after at least first line failure of chemotherapy)

2016 : First patients enrolled and dosed On-going study

Primary Endpoint: Overall Survival (OS)Secondary Endpoints:

Progression-free survival (PFS)Quality of Life (QOL)Overall response rate(ORR)Tolerance

Expected completion in 2018

Phase 3(n = 500)

TEDOPI® HLA-A2+(n=250)

Control GroupHLA-A2+(n=250)

NSCLC patientsat invasive or metastatic stage

in second or third line treatment

Atalante 1: On-going pivotal Phase 3 in EU-US

https://clinicaltrials.gov/ct2/show/NCT0265458

RATIONALE FOR TEDOPI® AND CKI COMBINATION12

• Combination is one of the pathways to fight such immune escape, to overcome immune resistance and to increase survival with manageable safety

• 2014: High expression of HLA and CD8 at tumor level are good prognosis factors*

• 2014: Immunotherapies increasing IFN-γ in tumor cells such as therapeutic vaccines, facilitate immune recognition of tumor cells (increase of MHC- I) in parallel with increased PD-L1 expression **

• 2016: High tumor neoantigens burden is associated with longer overall survival***

*Brown SD et al –Genome Research 2014**Grenga I et al. Journal for ImmunoTherapy of Cancer 2014

***Mcgranahan M et al- Science 2016

PD-L1 - PD-1 are T targets of Checkpoints Inhibitors (CKI) in the tumor microenvironmentCKI Immune escape is an emerging issue, and

survival remains at 11 months in NSCLC (2nd line)

EFFI-DEM: NEW GENERATION OF CHECKPOINT INHIBITORS13

Effi-DEM, in preclinical development, targets particular suppressor cells (SIRP-α on strategic pathwayCD47/SIRP-α) present in the tumor microenvironment, associated with a poor prognosis in aggressive cancers as they are linked to malignant progression: Myeloid-derived suppressor cells (MDSC) and macrophages called Tumor Associated Macrophages or TAM. Effi-DEM is a new CKI transforming these suppressive cells in active cells in various tumor efficacy studies.

Private public program INSERM ITUN Nantes CHU Effimune non interventional study exploring SIRP-alpha / MDSC/ TAM in human hepatocarcinoma.

MDSC and TAM suppressive cells role in the tumor microenvironment

EFFI-DEM: TACKLES MYELOID SUPPRESSIVE CELLS (MDSC, TAM)WHILE PROMOTING MACROPHAGES PHAGOCYTOSIS AND DENDRITIC CELLS FUNCTION

OSE IMMUNOTHERAPEUTICS DISCOVERY: SIRP-Α IS EXPRESSED BY MDSC AND TAMS AND CONTROLS THEIR

DIFFERENTIATION/POLARIZATION

First-In-Class

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EFFI-DEM: IN VIVO PROOF OF CONCEPT IN MONOTHERAPY AND IN VARIOUS

COMBINATIONS

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SIRP-α blockade induces MDSC differentiation into non-suppressive effector cells

SIRP-α blockade prevents Macrophage pro-tumoral suppressive action

• IN MONOTHERAPY :SIRP-α INHIBITS BREAST CANCER GROWTH

• IN COMBINATION :

SIRP-α SHOWS SYNERGY WITH ANTI PD-L1 IN HEPATOCARCINOMA MODEL

SIRP-α SHOWS SYNERGY WITH AGONIST 4-1BB MAB IN HEPATOCARCINOMA MODEL

AND INCREASE OF EFFECTOR IMMUNE CELLS INFILTRATES

FR104: CD28-ANTAGONIST IN REGULATION IMMUNOTHERAPY

FR104, Phase 2 status: a CD28-antagonist, is an optimized monoclonal antibody fragment targeting the CD28receptor, a key receptor in effector T lymphocytes. These effector lymphocytes are harmful in the case ofautoimmune diseases and transplantations. Product of new generation for rheumatoid arthritis andtransplantation*.

Phase 1 clinical trial completed with positive results.

License agreement with Johnson & Johnson (Janssen Biotech), responsible for all clinical development, registration and commercialization activities internationally. Under this agreement, OSE Immunotherapeuticsis eligible to receive up to a potential total of €155 million ($172 million).

*Anti-CD28 Antibody and Belatacept Exert Differential Effects on Mechanisms of Renal Allograft Rejection; Simon Ville, Nicolas Poirier et al.; Journal of the American Society of Nephrology; May 2016

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EFFI-7: IL RECEPTOR 7 ANTAGONIST IN REGULATION IMMUNOTHERAPY17

Effi-7, in preclinical development: Antagonist of the Interleukin 7 alpha receptor, Effi-7 is a monoclonalimmunomodulatory antibody targeting the CD127 receptor, the alpha chain of the Interleukin 7 receptor,for a long-term control of the pathogenic T cells in intestines as Inflammatory Bowel Diseases (i.e.ulcerative colitis). Preliminary results show a pharmacological profile with a dose/effect relationship and asatisfactory safety profile. Confirmed efficacy in in vivo model of ulcerative colitis.

Partially financed by Bpifrance for an amount of €9.1M, being developed as part of the EFFIMabconsortium lead by OSE Immunotherapeutics (with academic and private partners) for a total amountof €20M until phase 2.

EXPERIENCED MANAGEMENT TEAM

FROM DISCOVERY TO MARKET

Emile Loria, M.D., Chairman

• Multiple executive positions Pharma /Biotech last 25 years

• Ciba-Geigy, Sanofi, Cygnus, Biovector, Epimmune, BioAlliancePharma

• Track Record of Licensing agreements

• President & CEO Epimmune (Nasdaq) 2001-2006

• Asset Purchase Agreement with Takeda for OSE2101-Tedopi® and Memopi® (2011-2012)

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Alexis Peyroles, COO, Operations, Finance, BD - MBA London Imperial College, EDHEC

• Financial expertise in large Pharma and international operations positions last 15 years

• Sanofi Controller, Japan / Eastern countries

• Guerbet – Finance Director / GM Latin America (Brazil)

• CFO/BD of OSE Pharma (2013)

Dominique Costantini, M.D., Immunology, CEO

• Extensive experience of product development in Pharma / Biotech last 20 years

• Roussel-HMR-Sanofi

• Track record of approved products EU/USA in Oncology • Founder & CEO BioAlliance Pharma listed on Euronext

(1997-2011), Founder & CEO of OSE Pharma (2012)

Maryvonne Hiance, Vice Chairman & Director of Strategy

• Over a 20 year period, held the position of General Manager at innovative biotechnology companies (SangStat Atlantic, DrugAbuse Sciences and TcLand)

• Previously member of the French Strategic Council for Innovation, Advisor to the French SMEs & Industry Ministry.

• Founder & Chairman of Effimune (2008)

Bernard Vanhove, COO, R&D and International scientific collaborations

• Extensive international scientific experience

• Research Director at the CNRS, INSERM and ITUN

• Prize from « France Transplant » for pharmacologicalpreclinical studies on FR104

• Co-founder and CEO of Effimune (2008)

FIRST-HALF 2016 POSITIVE FINANCIAL RESULTS DRIVEN BY KEY CLINICAL

MILESTONES

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In k€ 06/30/2016 06/30/2015

Operating result 22 290 (2 800)

Net result 24 506 (2 942)

In k€ 06/30/2016 12/31/2015

Available cash* 15 275 15 133

Consolidated balance sheet 82 652 16 995

Available cash of €15 million as of 30 June 2016

+ €10 million received from J&J (Aug) in payment of exercise of license option

Providing a financial visibility until S2 2018

*Available cash and cash equivalents and current financial assets

NEXT MILESTONES: NEAR AND MID TERM CATALYSTS TO DRIVE VALUE20

2016

Tedopi® in combination with a Checkpoint inhibitor

Phase 2 considered

2017

Tedopi®

pivotal trial Phase 3 EU- US

FR104License agreement with Janssen, Ph 1

completed

→Phase 2 expectedin 2017

Tedopi®

Additional pharma agreement (BRIC/ emerging country)

Progress of the portfolio :

Tedopi®

Effi-7

Effi-DEM

R&D

2018

Tedopi®

End of the pivotal trial expected in

2018

Launch expected in 2019/2020

US/Europe

OSE IMMUNOTHERAPEUTICS: A NEW AND ATTRACTIVE PROFILE21

Leader in activation and regulation immunotherapy

Extended portfolio with diversified risk profile

1st worldwide license agreement with Johnson & Johnson

Innovative products blockbuster’s potential in attractive immunotherapy markets: immuno-oncology & auto-immune diseases

Experienced international team and network of experts in immunotherapy

Attractive portfolio to implement strategic pharma partnerships

A powerful company to catch growth opportunities

Financial visibility up to S2 2018

A SIGNIFICANT PLAYER

IN ACTIVATION AND REGULATION

IMMUNOTHERAPIES

Contacts:Dominique Costantini, CEOdominique.costantini@ose-immuno.comMob +33 6 13 20 77 49

Alexis Peyroles, DGD, Operations, Finance & BDalexis.peyroles@ose-immuno.comMob : +33 6 11 51 19 77

Company information: http://ose-immuno.com/en/