Next-generation neoantigen-targeted solid tumor T cell therapy

July 2021

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This presentation contains “forward-looking” statements that are within the meaning of federal securities laws and are based on our

management’s beliefs and assumptions and on information currently available to management. Forward-looking statements include

information concerning our possible or assumed future results of operations, business strategies, clinical trials and pre-clinical studies,

regulatory approval of our product candidates, liquidity position and capital needs, financing plans, industry environment, potential growth

opportunities, potential market opportunities and the effects of competition.

Forward-looking statements include all statements that are not historical facts and can be identified by terms such as “anticipates,”

“believes,” “expects,” “could,” “seeks,” “estimates,” “intends,” “may,” “plans,” “potential,” “predicts,” “projects,” “should,” “will,” “would” or

similar expressions and the negatives of those terms. Forward-looking statements represent our management’s beliefs and assumptions only

as of the date of this presentation. Our operations involve risks and uncertainties, many of which are outside our control, and any one of

which, or combination of which, could materially affect our results of operations and whether the forward-looking statements ultimately

prove to be correct. Factors that may materially affect our results of operations include, among other things, our ability to progress product

candidates in preclinical and clinical trials, the ability of ATLAS™ to identify promising oncology vaccine and immunotherapy product

candidates, the scope, rate and progress of our preclinical and clinical trials and other research and development activities, anticipated

timing of IND applications and new clinical trials, the amount of funds that we may require to conduct our clinical trials for our product

candidates, the timing of, and ability to, obtain and maintain necessary regulatory approvals for our product candidates, and those listed

in our Annual Report on Form 10-K for the fiscal year ended December 31, 2020 and other filings with the Securities and Exchange

Commission (“SEC”). Except as required by law, we assume no obligation to update these forward-looking statements publicly, or to update

the reasons actual results could differ materially from those anticipated in the forward-looking statements, even if new information becomes

available in the future.

You may get copies of our Annual Report on Form 10-K, Quarterly Report on Form 10-Q and our other SEC filings for free by visiting

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Disclaimer

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Genocea: a compelling near-term investment opportunity

TARGETS MATTER

Pioneering neoantigen-targeted

T cell therapy

Differentiated antigen discovery platform

Clinical proof-of-concept for ATLAS™

GEN-009 neoantigen vaccineBest-in-class immunogenicity, clinical

efficacy

GEN-011Ph1/2a trial in refractory patients

Initial readout late Q4/Q1 ‘22

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ATLAS:Better efficacy from choosing the right antigens,

ruling out the wrong antigens

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ATLAS: high throughput platform identifying and prioritizing surface-presented antigens

Inhibigen:

T cells inhibit cytokine secretion

Antigen:

T cells secrete inflammatory cytokinesTransfection of bacterial vectors with

plasmids expressing every candidate neoantigen

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ATLAS excludes Inhibigens: surface-presented antigens driving deleterious outcomes

1. Therapeutic mouse vaccination with a pool of ATLAS-identified Inhibigens drives tumor hyperprogression

2. The presence of Inhibigens in an otherwise protective mouse vaccine completely abrogates protection

3. Checkpoint blockade cannot overcome Inhibigen-mediated suppression

4. Inhibigen mechanism-of-action is not associated with increased Tregs

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1 Sahin, et al., Nature 2017 (N=8); Ott, et al., Nature 2017 (N=8); Gritstone ESMO Immuno-Oncology Congress Presentation 2019

• Results shown represent highest proportion of neoantigen-specific responses in peer publications and presentations

2Lam et al. Cancer Discovery 2021

Immune response frequency% neoantigens with immune responses

60%

Best peer neoantigen vaccine results1

Achieved in combination with CPI

99%

GEN-0092

Monotherapy

ATLAS enabled GEN-009 to drive unprecedented clinical immunogenicity results

Vaccine design:

• Neoantigen-specific synthetic long peptides + Hiltonol® adjuvant

Trial design:

• Phase 1/2a Part A: monotherapy dosing in cancer patients with no evidence of disease

Conclusions:

• ATLAS-identified neoantigens were immunogenic in all subjects, with responses detected to 99% of the vaccine antigens

• 6 of 8 patients recurrence-free with 2 years’ median follow-up

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ATLAS enabled a compelling signal of GEN-009 clinical response in checkpoint-sensitive patients

Design:• GEN-009 dosed after ~4 months on standard-of-care CPI; patients used as own control to identify GEN-009-specific clinical effectConclusions:• 4 CPI sensitive pts experienced deeper responses for up to 15 months after GEN-009 dosing.

– 6 of the 8 pts who received full courses of GEN-009 have not progressed with stable disease post GEN-009 from 6 to 13 months.– 4 of 8 (50%) evaluable patients achieved an objective response after a new baseline at start of GEN-009, including 1 CR and 3 PR.

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ATLAS drives evidence of stabilization in checkpoint-resistant patients

Design:• Patients not well controlled on standard-of-care CPI; received salvage therapy on top of CPI; after stabilization received GEN-009

Conclusions:• Disease control in refractory pts for up to 10 months

– 1 of 7 pts has achieved a PR, and 2 have prolonged stable disease up to 10 months after starting GEN-009

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Enables greater efficacy

Benefits

Enables therapies for all patients

Scalable

ATLAS advantages

Identifies all true neoantigens: i.e., all surface-presented peptides eliciting anti-tumor T cell responses. Delivers cell therapies and vaccines that minimize tumor escape

Avoids Inhibigens that may be detrimental to clinical response

Identifies both CD8+ and CD4+ T cell neoantigen targets to deliver cell therapies and vaccines that provide a powerful, comprehensive anti-tumor immune response

Superior clinical responses demonstrated by GEN-009’s best-in-class data

Can address all HLA types with a single platform and process

Highly industrialized process

ATLAS has powerful advantages over other neoantigen selection and targeting approaches

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GEN-011 Neoantigen-targeted peripheral blood T cell therapy (NPT)

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First-generation solid tumor cell therapies have demonstrated activity but have significant limitations

Tumor-infiltrating lymphocyte (TIL)

= TCR that is not tumor-specific

= neoantigens

TCR-transduced (TCR-T)

Strengths• Does not require extra tumor sampling and

TIL extraction• Uses less exhausted T cells

Strengths – durable efficacy in certain CPI-refractory patients, driven by:• Multiple target antigens (to limit tumor escape)• Polyclonal TCRs (to maximize “shots on goal”

for every target)• CD8+ and CD4+ T cells (to maximize natural

tumor-killing T cell responses)

Limitations• Inconvenience, cost of extra tumor sampling

and TIL extraction• Majority of product may not be tumor-

relevant• Exhausted cells

Tumor cell

Limitations• HLA limited• Single target and TCR per product

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Peripheral blood and pre-existing

tumor sample

Better targets

Prioritizes up to 30 tumor-and immune system-relevant neoantigens

Proprietary T cell expansion process

GEN-011: Next-generation solid tumor cell therapy -

Neoantigen-targeted Peripheral T cells (NPTs)

GEN-011

NPTs: Neoantigen-targeted peripheral T cells

Proprietary neoantigen selection platform

Better T cells

Expands peripherally-derived CD8+ and CD4+ T cells on ATLAS-prioritized

neoantigens

Better Targets + Better T cells Improvements in efficacy, accessibility and scalability

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• Accessibility: Peripheral blood collection is simple, fast, inexpensive, and can be done for nearly any patient

• Potency: Peripheral T cells have the promise to be more active and proliferative than TILs

• Proven efficacy: Peripheral T cells drive the efficacy of CPI therapy; they have the right neoantigen specificities and know how to home to tumors / kill tumor cells

Recent publications highlight benefits of peripheral T cells / NPTs

Circulating clonally expanded T cells reflect functions of tumor-infiltrating T cells

Peripheral T cell expansion predicts tumor infiltration and clinical response

Clonal replacement of tumor-specific T cells following PD-1 blockade

Sensitive and frequent identification of high avidity neo-epitope specific CD8+ T cells in immunotherapy-naive ovarian cancer

Better T cellsT cells from peripheral blood have significant advantages over TILs

NPT benefits

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Robust and rapidly scalable manufacturing process with fully closed single-use technology

Peripheral blood (leukopak)

Up to 30 verified neoantigens

Expansion of neoantigen-specific cells in fully closed single-use GRex

vessels

T cells

Phenotypic cell sort

Monocyte-derived dendritic cells

Peripheral blood from every patient, dramatically expanding accessible patient population

Robust process designed to deliver billions of cells for every patient

Modular, rapidly expandable manufacturing process

Cost, time-to-delivery expected to be favorable compared to TIL and TCR-T therapy

process

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GEN-011 delivers billions of NPTs that are:

Highly neoantigen-specific

96% Antigen Specific

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Activation Marker 1

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Effector:Target ratio

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Specific NeoantigensUnpulsed Control

Powerfully cytolytic against their targets

GEN-011 TIL20

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More active and potent compared to TIL

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Naive Terminal memory

Memory (Cm+Em)

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The desired memory phenotype

1. Ritthipichai, SITC 2017

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89%

GEN-011 NPTs are specific for 89% of all intended neoantigen targets*

*Mean across development runs with cancer patient material

Recent selected TIL data show successful amplification to only 4% of antigens included in the process1

Recent conventional TIL data show responses to an average of 6% of the predicted neoantigens2

Recent engineered TCR-T data suggest only up to 3 neoantigen specificities targeted3

GEN-011 targets up to 30 neoantigens

1. Samuel et al., AACR Presentation (April 2020)2. Creelan et al., AACR Presentation (April 2020)

3. Cristea et al., 2020 AACR Presentation (April 2020)

GEN-011 provides unparalleled breadth of neoantigen coverage

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Greater efficacy

Greater accessibility, broad addressable patient population

Scalable, cost-effective production process

GEN-011 Advantages

GEN-011 overcomes limitations of 1st

generation solid tumor therapies

Features GEN-011 TIL TCR-TTargets up to 30 neoantigens to limit tumor escape

Avoids Inhibigens that may be detrimental to clinical response

Includes CD4+ and CD8+ neoantigen-specific T cells

Non-exhausted T cells with potential for superior activity and persistence

Can treat all HLA types

No extra surgery or viable tumor required

No TCR vector design and transduction required

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trial: Phase 1/2a study of GEN-011 in patients with CPI–resistant solid tumors

Trial Objectives

Initial clinical readout expected late Q4 / Q1 2022

Cohort AMultiple low dose (up to 12 patients)• No lymphodepletion• Intermediate dose IL-2

• Safety• Clinical activity

• ORR• DOR

• GEN-011 proliferation and persistence

• Tumor T cell penetration

Trial objectivesPatients with immune responsive tumors that have not achieved an adequate response after PD-1 based therapy

Melanoma, NSCLC, SCLC, SCCHN, UC, RCC, SqCC skin, SqCCAC

Targeted indications

Cohort BSingle high dose (up to 12 patients)• Lymphodepletion• High dose IL-2

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CD8+ and CD4+ T cells targeting up to 30 neoantigens

Robust and rapidly scalable manufacturing process

Peripheral blood enabling greater accessibility, activity and durability

GEN-011: Transforming neoantigen

T cell therapy for solid tumors

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Genocea: a compelling near-term investment opportunity

TARGETS MATTER

Pioneering neoantigen-targeted

T cell therapy

Differentiated antigen discovery platform

Clinical proof-of-concept for ATLAS™

GEN-009 neoantigen vaccineBest-in-class immunogenicity, clinical

efficacy

GEN-011Ph1/2a trial in refractory patients

Initial readout late Q4/Q1 ‘22

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