Bringing Breakthrough Pioneering Therapies to Patients with Life-Threatening Diseases

Corporate Presentation

December 2017

Disclaimer

In addition to historical facts or statements of current condition, this presentation contains forward-looking statements, includingstatements about the potential safety and feasibility of CYAD-01 cell therapy, including current and planned preclinical and clinical trials forCelyad’s product candidates; the clinical and commercial potential of these product candidates and the adequacy of Celyad’s financialresources; Celyad’s intellectual property portfolio, including plans related thereto; Celyad’s expectations regarding its strategiccollaborations and license agreements with third parties, including Novartis, Celdara Medical, and Dartmouth College, and the potentialimpact of such collaborations on Celyad’s future financial condition; and Celyad’s expected cash burn, which reflect Celyad’s currentexpectations and projections about future events, and involve certain known and unknown risks, uncertainties and assumptions that couldcause actual results or events to differ materially from those expressed or implied by the forward-looking statements. These forward-looking statements are further qualified by important factors and risks, which could cause actual results to differ materially from those in theforward-looking statements, including risks associated with conducting clinical trials; the risk that safety, bioactivity, feasibility and/orefficacy demonstrated in earlier clinical trials or preclinical studies may not be replicated in subsequent trials or studies; risks associated withthe timely submission and approval of anticipated regulatory filings; the successful initiation and completion of clinical trials, including itsclinical trials for CYAD-01; risks associated with the satisfaction of regulatory and other requirements; risks associated with the actions ofregulatory bodies and other governmental authorities; risks associated with obtaining, maintaining and protecting intellectual property,Celyad’s ability to enforce its patents against infringers and defend its patent portfolio against challenges from third parties; risks associatedwith competition from others developing products for similar uses; risks associated with Celyad’s ability to manage operating expenses; andrisks associated with Celyad’s ability to obtain additional funding to support its business activities and establish and maintain strategicbusiness alliances and business initiatives. A further list and description of these risks, uncertainties and other risks can be found in Celyad’sU.S. Securities and Exchange Commission (SEC) filings and reports, including in its Annual Report on Form 20-F filed with the SEC on April 4,2017 and subsequent filings and reports by Celyad. Given these uncertainties, the reader is advised not to place any undue reliance on suchforward-looking statements. These forward-looking statements speak only as of the date of publication of this document. Celyad expresslydisclaims any obligation to update any such forward-looking statements in this document to reflect any change in its expectations withregard thereto or any change in events, conditions or circumstances on which any such statement is based, unless required by law orregulation.

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Focused on the discovery and the development of specialized cell-based therapies to target cancer

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• Novel and proprietary CAR-T platform targeting treatment of solidand hematological tumors

• Lead candidate, CYAD-01 (CAR-T NKG2D), currently enrolling in THINK trial in 7 indications

• CAR-T NKG2D target validated with first complete response in AML

• Unique expertise in cell manufacturing

• Strong IP position

• Partnerships with first-class corporate, academic institutions

Stress ligands, the making of an ubiquitous CAR-T

CD19-CAR-T CYAD-01 CAR-T

• Derived from a

(murine) antibody

• 2nd generation CAR-

T signaling

• scFv targeting

specific cancers

• Derived from

human NK receptor

• Similar primary and

secondary signaling

• NKG2D receptor

targeting stress

signals present on

most cancers

scFv

CD8TM

CD28

CD3ζ

NKG2D

DAP10

CD3ζ

SIGNAL 2

SIGNAL 1

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NKG2D binds to 8 stress induced ligands, expressed in a broad range of cancer indications

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Expression of at least one of NKG2D ligands:

• Triple negative breast: 88%

• Colorectal: 88%

• Ovarian: 68%

• Bladder: 78% of the primary tumors and 100% of the metastases

• Pancreatic: 86%

• NSCLC Lung: 92% (100% non-squamous NSCLC)

Dulphy N., Toubert A. et al. 2017. Unpublished data. Celyad 2017. Unpublished data, IHC.

Beyond direct cell killing, inducing multi faceted attack on the tumor

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CYAD-01

DIRECT TUMOR CELL KILLING

ANTI-NEOANGIOGENEIC EFFECT DRIVEN THROUGH TARGETING OF TUMOR ENDOTHELIAL

CELLS EXPRESSING NKG2D LIGANDS

RELEASE OF THE IMMUNOSUPPRESSION OF THE TUMOR MICROENVIRONMENT

ADAPTIVE IMMUNE RESPONSE: SPECIFIC ANTITUMOR RESPONSE POST CYAD 01 TREATMENT

Lonez et al. 2017 BMJ Open 7:e017075.

Blood vesselsTumor cells

Immunosuppressive cells

Host Immune cells

CYAD-01 preclinical models showing activity with multiple injections and without pre-conditioning

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MULTIPLE MYELOMALYMPHOMAOVARIAN CANCER

Zhang et al., 2007 Cancer Res; 67: (22)Barber et al. 2009 J Immunol. 183(4):2365-72 Barber et al., 2011 Gene Ther. 18(5):509-16

Safety Phase I

▪ 1 administration▪ No lymphodepletion▪ Low sub-therapeutic

doses▪ Hematological tumors

(AML/MM)

2015 2016

• Run at Dana Farber Cancer Institute• CYAD 01 is safe at the dose levels tested• One r/r AML Patient at highest dose (3x107) showed normalization of all

hematologic parameters for 6 months

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FIM Phase I Study: CYAD 01 is safe and shows early signs of activity

THINK Trial

▪ Seven advanced refractory tumor indications:

Hemato: Acute Myeloid Leukemia, Multiple Myeloma

Solid: Ovarian, Colorectal, Pancreatic, Bladder, Triple Negative Breast cancer

▪ Global development: EU and USA

▪ Safety and clinical Activity: CYAD-01

o 3 dose levels (3x108,1x109 and 3x109)

o 3 administrations for each patient

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▪ 3 administrations▪ No lymphodepletion▪ Hematological & solid

tumors

2016 Q2-2018

Apheresis

1st CYAD-01 (D1)2nd CYAD-01 (D2)

3rd CYAD-01 (D3)

End safety

D1 D15 D29

Tumor assessment

D43 D57D-21

Washout period

13 weeks w/o any other non-investigational cancer therapy

THINK Study (THerapeutic Immunotherapy w/ NKG2D-based therapy)

D-35

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1st CYAD-01D1

3rd CYAD-01D29 M6M3

Tumor evalD57

Safety evalD43

2nd CYAD-01D15Apheresis

Pat 101-501-AML

Pat 202–501-AML

Pat-101-502-AML

DL1 (3x108/dose)

DL2 (1x109/dose)

PD

MLFS MLFS Allo-HSCT

CRi

Allo-HSCT Allogeneic hematopoietic stem cell transplantationCRh Complete remission with partial hematologic recoveryCRi Complete remission with incomplete hematologic recoveryMLFS Morphological leukemia-free stateSD with HI Stable disease with hematologic improvementPD Progressive diseaseOOT Patient left trial to undergo another therapy

Source: Electronic Case Report Forms, as reported by Investigators

SD with HI

Dose escalation Heme: 3 activities in the first 3 AML patients

OOT

OOT

Preliminary take away from AML patients in THINK

• Clinical activity of CYAD-01 reported in 100% patients dosed (n=3)

• Blast reduction in BM in all patients up to and including at least the third injection

• Hematological parameters improving

• No safety concerns (low grade CRS, no neurotoxicity)

➢ Next steps in THINK: Complete Dose level 2 and 3; Expansion cohort according to ORR

• Half-way through dose level 2 (1x109)

• End of dose study expected end Q1 2018

• Patient data submitted for scientific publication

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CYAD-01 in AML, the path to registration(s)

AML SoC

Increase Durability Through Multiple

Injections

Enhance engraftment and

expansion

Increase immediate potency through

debulking

Broaden patient population

THINK

Standard CAR-T preconditioning

regimen to induce lymphodepletion

AML preconditioning

Combination with 2nd line standard of care

chemotherapy regimen

SIBLINKDonor-derived CYAD-01

infused in patients in remission post allo-graft

First FOCUS ON AML in Hematological

Tumors

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Boosting potency:

• Expansion

• Tumor debulking

Prolong durability

AML is a large unmet medical need, distinct from B cell malignancies

CD

19

mal

ign

anci

es

AML

• 21.380 NCY• 26.9% 5 Y Survival

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ALL

• 5.970 NCY• 68.2% 5 Y Survival

DLBCL

• 27.650 NCY• 53% 5 Y Survival

THINK trial (solid arm); promising early results at first dose level

• Two out of three metastatic colorectal cancer patients reported as “stable disease” up to 3-months follow-up*

• No toxicity signals to date

➢ Next steps: Higher doses, longer follow-up + SHRINK and LINK

* Median progression free survival in these patients under standard of care is between 1.9 and 3.2 months(e.g. Regarifinib or trifluridine/tipiracil).

Sources: Grothey et al., 2013 Lancet. 381(9863):303-12; Li et al., 2015. Lancet Oncol. 16(6):619-29;Moriwaki et al., 2017. Oncologist. 2017 Sep 11.

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CYAD-01 in CRC, the road to CAR-T in solid tumors

CRC + SOC(SHRINK)

Prolong durabilitythrough multiple

injections

Enhance engraftment and

expansion

Increase potency through debulking

Favor tumor homing

THINK

Standard CAR-T preconditioning regimen

CRC preconditioning

1st line standard of care chemotherapy regimen

for metastatic CRC

LINK

Local infusion in hepatic artery for primary liver

metastasis of CRC

First FOCUS ON CRC in Solid

Tumors

Boosting potency through:

• Expansion

• Tumor debulking

• Homing

Prolong durability

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CYAD-01 Updated Clinical Development Plan

2017 2018 2019

Study FPFV End of enrolment

Intermediate results from dose escalation phase

Study results

ASCO Deadline ASH DeadlineAACR Deadline

ASCO ASH AACR

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SIBLINK

THINK CRC

THINK AML

SHRINK

LINK

CRC preconditioning

AML preconditioning

AML SOC

Manufacturing autologous cell therapies – delivering the promise

• Automation and closing of the manufacturing chain

• Automating manufacturing and QC

• Automating release

• Reducing COGS and infrastructure needs

• Towards a fully automated point of care manufacturing system

• Reducing logistical burden

• Overhauling the value chain

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Closing and automating the manufacturing chain

PARADIGM SHIFTING AUTOMATION:

• For centralized and decentralized cell manufacturing based upon cartridge culture system and multiple parallel processing capability

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Vector is added to the CPU through a slot in the door (shown in blue) at the beginning of the transduction process.

The cartridge is loaded onto the CPU trolley first. It comprises of all components required for completing the process.

Bulk reagents consist of 6 individual components that are

assembled onto the cartridge as part of setup

CYAD-101: Making allogeneic options feasible

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• Engineered for CYAD-01 (NKG2D-based CAR-T cell)

• Alloreactivity controlled through co-expression of an inhibitory peptide (termed a T cellreceptor inhibitory molecule – TIM) to reduce TCR-signaling and thereby reduce GvHD.

05/12/2017

Abrogation of GvHD by the expression of TIM8 in allogeneic T cells

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0 2 0 4 0 6 0

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5 0

1 0 0

D a y s p o s t in fu s io n

Su

rv

iva

l (%

)

D o n o r T c e lls

D o n o r T IM 8 T c e lls

N o T ce lls

0 5 1 0 1 5 2 0 2 5

1 0 7

1 0 8

1 0 9

1 0 1 0

1 0 1 1

D a y s p o s t in fu s io n

Bio

lum

ine

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en

ce

(ph

oto

ns

/ s

ec

/ m

m2

)

C o n tro l

tC D 1 9 T c e lls

T IM 8 .N K R 2

* *

Vehicle tCD19 TIM8.

CYAD-101

The expression of TIM8 inhibits xGvHD in the NSG mouse

CYAD-101

Tumor growth (orthotopic colorectal tumor in NSG mice) isdecreased following treatment with CYAD-101

Summary: Towards CAR T leadership

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NKG2D platform;Leveraging Stress Ligands

based CAR-T

Autologous Cell Manufacturing Paradigm shift

Allogeneic CAR T Cell Therapy

Building on early signals

Improving outcomes

Process Development

Improved yields and CoGs

Strong IP position

Patents concerning TCR knockdown in CAR T cell therapy providing

exclusivity in the field

Towards BTD/PRIME in AML and CRC

Execution

Continuing Development Plan

Broaden indications beyond AML and CRC

Automation

Making Autologous Cell Therapies feasible and cost effective

Allogeneic NKG2D Platform

Development of TIM8-CYAD 01 (CYAD-101)

Towards Point of Care Processing

Enabling large indications

Allogeneic TIM Platform

Developing broad based Allogeneic CAR –T products

Corporate partnerships

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• July 11th 2016: Celyad grants exclusive license to ONO for the development and commercialization of allogeneic CYAD-01 T-cell immunotherapy in Japan, Taiwan and Korea (=10% of the worldwide pharmaceutical market)

• License in exchange for $12.5M upfront, $300M inpotential milestones and double-digit royalties

• May 2nd, 2017: Celyad grants to Novartis a non-exclusive license for its allogeneic TCR-deficientCAR-T cells patents for two undisclosed targets

• Deal value: $96 million. Celyad to receive upfront, development and commercial milestones payments and single digit royalties

• Celyad retains all rights to grant further licenses to third parties for the use of allogeneic CAR-T cells. Deal can be turned into exclusive license

Financial snapshot

Cash Position:

• €40 million as of September 30, 2017

• Enabling company’s activities through the first half of 2019

Ticker: Nasdaq (CYAD), Euronext Paris & Euronext Brussels (CYAD.BB)

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Management team

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1 2 3

4 5

7 8

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1. Christian Homsy, CEO2. Patrick Jeanmart, CFO3. Jean-Pierre Latere, COO4. Frédéric Lehmann, VP Clinical Development & Medical Affairs5. David Gilham, VP R&D6. Georges Rawadi, VP Business Development & IP7. Philippe Dechamps, Chief Legal Officer8. Philippe Nobels, Global Head Of Human Resources

Thank you

BELGIUMCelyad SAAxis Business ParkRue Edouard Belin, 2B-1435 Mont-Saint-Guibert+32(0) 10 39 41 00

USACelyad Inc.Seaport East 2 Seaport LaneBoston, MA. 02210+1 857-990-6900

www.celyad.com

Contact: investors@celyad.com