Harnessing Novel Immunobiology November 2018 Safe Harbor Statement This presentation contains forward-looking statements about Equillium, Inc. (the "Company"). In some cases, you can identify forward-looking statements b

Harnessing Novel Immunobiology November 2018

Safe Harbor Statement This presentation contains forward-looking

statements about Equillium, Inc. (the "Company"). In some cases, you can identify forward-looking statements by the words "will," "expect," "intend," "plan," "objective,"

"believe," "estimate," "potential," "continue" and "ongoing," or the negative of these terms, or other comparable terminology intended to identify statements about the future. These

statements are based on Company management's current beliefs and expectations. These statements include but are not limited to statements regarding the Company's business strategy, the Company's plans to develop and commercialize

its product candidates, the safety and efficacy of the Company's product candidates, the Company's plans and expected timing with respect to regulatory filings and approvals, and size and growth potential of the markets for the

Company's product candidates. These statements involve substantial known and unknown risks, uncertainties and other factors that may cause the Company's actual results, levels of activity, performance or achievements to be materially

different from the information expressed or implied by these forward-looking statements. The Company may not actually achieve the plans, intentions or expectations disclosed in its forward-looking statements, and you should not place undue reliance

on the Company's forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed or implied in the forward- looking statements the Company makes due to the risks and

uncertainties inherent in the Company's business, including without limitation, risk described in the Company's filings with the Securities and Exchange Commission ("SEC"). You are cautioned not to place undue reliance on

these forward-looking statements, which represent the Company's views as of the date of this presentation. The Company's anticipates that subsequent events and developments will cause the its views to change. However, while the Company

may elect to update these forward-looking statements at some point in the future, the Company has no current intention of doing so except to the extent required by applicable law. Further information regarding these and other risks is included under

the heading "Risk Factors" in the Company's final prospectus relating to the Company's Registration Statement on Form S-1, as amended (File No. 333-227387), filed with the SEC and the Company's other reports, which may

be accessed for free by visiting EDGAR on the SEC web site at http://www.sec.gov. and on the Company's website under the heading "Investors." All forward-looking statements are qualified in their entirety by this cautionary

statement. This caution is made under the "safe harbor" provisions of Section 21E of the Private Securities Litigation Reform Act of 1995. 2Safe Harbor Statement This presentation contains forward-looking statements about Equillium, Inc.

(the "Company"). In some cases, you can identify forward-looking statements by the words "will," "expect," "intend," "plan," "objective," "believe,"

"estimate," "potential," "continue" and "ongoing," or the negative of these terms, or other comparable terminology intended to identify statements about the future. These statements are based on

Company management's current beliefs and expectations. These statements include but are not limited to statements regarding the Company's business strategy, the Company's plans to develop and commercialize its product candidates,

the safety and efficacy of the Company's product candidates, the Company's plans and expected timing with respect to regulatory filings and approvals, and size and growth potential of the markets for the Company's product

candidates. These statements involve substantial known and unknown risks, uncertainties and other factors that may cause the Company's actual results, levels of activity, performance or achievements to be materially different from the

information expressed or implied by these forward-looking statements. The Company may not actually achieve the plans, intentions or expectations disclosed in its forward-looking statements, and you should not place undue reliance on the

Company's forward-looking statements. Actual results or events could differ materially from the plans, intentions and expectations disclosed or implied in the forward- looking statements the Company makes due to the risks and uncertainties

inherent in the Company's business, including without limitation, risk described in the Company's filings with the Securities and Exchange Commission ("SEC"). You are cautioned not to place undue reliance on these

forward-looking statements, which represent the Company's views as of the date of this presentation. The Company's anticipates that subsequent events and developments will cause the its views to change. However, while the Company may

elect to update these forward-looking statements at some point in the future, the Company has no current intention of doing so except to the extent required by applicable law. Further information regarding these and other risks is included under the

heading "Risk Factors" in the Company's final prospectus relating to the Company's Registration Statement on Form S-1, as amended (File No. 333-227387), filed with the SEC and the Company's other reports, which may be

accessed for free by visiting EDGAR on the SEC web site at http://www.sec.gov. and on the Company's website under the heading "Investors." All forward-looking statements are qualified in their entirety by this cautionary statement.

This caution is made under the "safe harbor" provisions of Section 21E of the Private Securities Litigation Reform Act of 1995. 2

Executive Summary First-in-class: Equillium is developing EQ001

(itolizumab) the first antibody targeting the novel immune checkpoint pathway CD6 - for the treatment of severe immuno-inflammatory disorders Pipeline-in-a-product: as a unique T cell modulator, EQ001 has potential broad, best-in-class,

disease modifying therapeutic utility - U.S. IND open and launching multiple clinical studies in the first half of 2019 Validated therapeutic: itolizumab has shown clinical efficacy in multiple indications - studied by Biocon in >330

patients - and is approved for the treatment of psoriasis in India High-value partnership: Equillium acquired exclusive rights to EQ001 for the U.S. & Canada from Biocon - partnership provides clinical & commercial product,

commercial scale production at FDA regulated facility Accomplished team: experienced in drug discovery, development and commercialization EQ Financing: IPO completed in Q4 2018 raising $71.6 million in gross proceeds 3Executive Summary

First-in-class: Equillium is developing EQ001 (itolizumab) the first antibody targeting the novel immune checkpoint pathway CD6 - for the treatment of severe immuno-inflammatory disorders Pipeline-in-a-product: as a unique T cell modulator,

EQ001 has potential broad, best-in-class, disease modifying therapeutic utility - U.S. IND open and launching multiple clinical studies in the first half of 2019 Validated therapeutic: itolizumab has shown clinical efficacy in multiple

indications - studied by Biocon in >330 patients - and is approved for the treatment of psoriasis in India High-value partnership: Equillium acquired exclusive rights to EQ001 for the U.S. & Canada from Biocon - partnership

provides clinical & commercial product, commercial scale production at FDA regulated facility Accomplished team: experienced in drug discovery, development and commercialization EQ Financing: IPO completed in Q4 2018 raising $71.6 million in

CD6 Plays a Central Role in Immuno-inflammationCD6 Plays a Central Role

in Immuno-inflammation

Immuno-inflammation: Severe Disease, High Unmet Medical Need Acute

Graft-Versus- Host Disease Solid Organ Chronic Graft-Versus- Rejection Host Disease Multiple Sclerosis Crohn's Disease Neuromyelitis Optica Ulcerative Colitis Severe Asthma Vasculitis Lupus Interstitial Lung Diseases Scleroderma Chronic

Obstructive Pulmonary Disease Behcet's Disease Rheumatoid Arthritis Atopic Dermatitis Psoriatic Arthritis Psoriasis Uveitis 5Immuno-inflammation: Severe Disease, High Unmet Medical Need Acute Graft-Versus- Host Disease Solid Organ Chronic

Graft-Versus- Rejection Host Disease Multiple Sclerosis Crohn's Disease Neuromyelitis Optica Ulcerative Colitis Severe Asthma Vasculitis Lupus Interstitial Lung Diseases Scleroderma Chronic Obstructive Pulmonary Disease Behcet's Disease

Rheumatoid Arthritis Atopic Dermatitis Psoriatic Arthritis Psoriasis Uveitis 5

CD6 Plays a Central Role in Immuno-inflammatory Disease T cell mediated

diseases Acute Graft-Versus- Host Disease Solid Organ Chronic Graft-Versus- Rejection Effector T cells, or T , play an eff Host Disease important role in the pathogenesis of T cell mediated diseases driving Multiple Sclerosis Crohn's Disease

autoimmune and allergic Neuromyelitis Optica Ulcerative Colitis inflammation Severe Asthma Vasculitis CD6 is a tightly regulated, co- Lupus Interstitial Lung stimulatory receptor functionally Diseases important in modulating the Scleroderma Chronic

Obstructive Pulmonary Disease activation, proliferation, differentiation Behcet's Disease & trafficking of T cells eff Rheumatoid Arthritis Atopic Dermatitis Psoriatic Arthritis Psoriasis Uveitis 6CD6 Plays a Central Role in

Immuno-inflammatory Disease T cell mediated diseases Acute Graft-Versus- Host Disease Solid Organ Chronic Graft-Versus- Rejection Effector T cells, or T , play an eff Host Disease important role in the pathogenesis of T cell mediated diseases

driving Multiple Sclerosis Crohn's Disease autoimmune and allergic Neuromyelitis Optica Ulcerative Colitis inflammation Severe Asthma Vasculitis CD6 is a tightly regulated, co- Lupus Interstitial Lung stimulatory receptor functionally Diseases

important in modulating the Scleroderma Chronic Obstructive Pulmonary Disease activation, proliferation, differentiation Behcet's Disease & trafficking of T cells eff Rheumatoid Arthritis Atopic Dermatitis Psoriatic Arthritis Psoriasis

The Basis of Immuno-inflammation Immuno-inflammatory diseases can be

fundamentally characterized by an imbalance between effector cell and immuno-regulatory activity Tolerance Autoimmunity T reg T T reg f ef T eff T eff T eff 7The Basis of Immuno-inflammation Immuno-inflammatory diseases can be fundamentally

characterized by an imbalance between effector cell and immuno-regulatory activity Tolerance Autoimmunity T reg T T reg f ef T eff T eff T eff 7

CD6 is Central to Immuno-inflammation Highest levels of CD6 are found on

activated T effector cells (T ) and associated with eff amplification of the auto-reactive cascade Low/- CD6 CD6 + CD6 Hi T 1 h T 2 h T 17 h CD6 Immune Regulatory Autoreactive "Tolerance""Autoimmunity" 8CD6 is Central to

Immuno-inflammation Highest levels of CD6 are found on activated T effector cells (T ) and associated with eff amplification of the auto-reactive cascade Low/- CD6 CD6 + CD6 Hi T 1 h T 2 h T 17 h CD6 Immune Regulatory Autoreactive

"Tolerance""Autoimmunity" 8

CD6 Drives Pathogenic T Cell Activity & Trafficking Co-stimulation =

Activation Proliferation Differentiation / Survival Trafficking Suppression of regulatory pathways 9CD6 Drives Pathogenic T Cell Activity & Trafficking Co-stimulation = Activation Proliferation Differentiation / Survival Trafficking Suppression

of regulatory pathways 9

EQ001 Inhibits Pathogenic T Cell Activity & Trafficking Inhibition

= Activation Proliferation Differentiation / Survival Trafficking Restoration of regulatory pathways 10EQ001 Inhibits Pathogenic T Cell Activity & Trafficking Inhibition = Activation Proliferation Differentiation / Survival Trafficking

Restoration of regulatory pathways 10

Upstream, Disease Modifying Immuno-inflammatory Mechanism EQ001 is

designed to selectively target autoreactive effector T cell activity and trafficking, while sparing regulatory T cells to promote immune tolerance and durable disease remission Inhibition of T effector cells Inhibition of trafficking

Restoration of immune regulation upstream of current approaches into key target organs without immunosuppression T eff T eff T T eff eff T reg T eff T eff 11Upstream, Disease Modifying Immuno-inflammatory Mechanism EQ001 is designed to

selectively target autoreactive effector T cell activity and trafficking, while sparing regulatory T cells to promote immune tolerance and durable disease remission Inhibition of T effector cells Inhibition of trafficking Restoration

of immune regulation upstream of current approaches into key target organs without immunosuppression T eff T eff T T eff eff T reg T eff T eff 11

Clinical StrategyClinical Strategy

Itolizumab is Clinically Validated in Autoimmune Disease Phase 3

pivotal trial results: demonstrated efficacy & safety in psoriasis patients (n=223) Efficacious TREAT-PLAQ - Trial Results Safe & Tolerable Treatment Dosing Week 0-4 Dosing Week 5-12 PASI 75 Week 12 Dosing Week 12+ ALZUMAb Placebo Arm

Weeks 1-12 (n = 180) (n = 43) 0.4mg/kg QW 1.6mg/kg Q2W 27% (p = 0.0172) 1.6mg/kg Q4W 1.6mg/kg Q2W 1.6mg/kg Q2W 36% (p = 0.0043) 1.6mg/kg Q4W Any Adverse Event 72 (40.0%) 20 (46.5%) placebo placebo 2.3% 1.6mg/kg Q2W Infusion Reaction 33 (18.3%) 1

(2.3%) Infection 6 (3.3%) 4 (9.3%) Pruritus 5 (2.8%) 3 (7.0%) Durable Response Cross over point At week 28, itolizumab responders (PASI 75) were re-randomized into 2 groups Drug Withdrawal Group (placebo n = 40) 12 Weeks 28 Weeks

Baseline 53% maintained PASI 75 at 1-year Maintenance Therapy Group (itolizumab1.6mg/kg q12w n = 39) 67% maintained PASI 75 at 1-year 13Itolizumab is Clinically Validated in Autoimmune Disease Phase 3 pivotal trial

results: demonstrated efficacy & safety in psoriasis patients (n=223) Efficacious TREAT-PLAQ - Trial Results Safe & Tolerable Treatment Dosing Week 0-4 Dosing Week 5-12 PASI 75 Week 12 Dosing Week 12+ ALZUMAb Placebo Arm Weeks 1-12 (n

= 180) (n = 43) 0.4mg/kg QW 1.6mg/kg Q2W 27% (p = 0.0172) 1.6mg/kg Q4W 1.6mg/kg Q2W 1.6mg/kg Q2W 36% (p = 0.0043) 1.6mg/kg Q4W Any Adverse Event 72 (40.0%) 20 (46.5%) placebo placebo 2.3% 1.6mg/kg Q2W Infusion Reaction 33 (18.3%) 1 (2.3%) Infection

6 (3.3%) 4 (9.3%) Pruritus 5 (2.8%) 3 (7.0%) Durable Response Cross over point At week 28, itolizumab responders (PASI 75) were re-randomized into 2 groups Drug Withdrawal Group (placebo n = 40) 12 Weeks 28 Weeks Baseline 53%

maintained PASI 75 at 1-year Maintenance Therapy Group (itolizumab1.6mg/kg q12w n = 39) 67% maintained PASI 75 at 1-year 13

Opportunity in Multiple Severe Autoimmune Indications Scientific

Rationale Translational Research Commercial Analysis Clinical Development Genetic data implicates CD6 Bioinformatics High unmet medical need Clear development path + Pathogenic CD6 cells Cell-based assays

Steroid insensitive or refractory Identifiable patient population populations Underlying T / T imbalance Animal models Potential regulatory incentives reg eff Concentrated treatment base Human tissue analysis

KOL support and partnerships Target organs express ALCAM + known to traffic CD6 cells Reimbursement with leading centers Overall market opportunity Clinical design and timeline EQ001 Opportunity Set Therapeutic

Scientific Translational Commercial Therapeutic Area Clinical Plan Indication Rationale Research Opportunity aGVHD Transplant Science cGVHD Pulmonary severe asthma Systemic systemic lupus Autoimmunity scleroderma Crohn's Gastrointestinal

colitis multiple sclerosis Neuroinflammation neuromyelitis optica 14 Key Selection CriteriaOpportunity in Multiple Severe Autoimmune Indications Scientific Rationale Translational Research Commercial Analysis Clinical Development Genetic data

implicates CD6 Bioinformatics High unmet medical need Clear development path + Pathogenic CD6 cells Cell-based assays Steroid insensitive or refractory Identifiable patient population populations

Underlying T / T imbalance Animal models Potential regulatory incentives reg eff Concentrated treatment base Human tissue analysis KOL support and partnerships Target organs express ALCAM + known to traffic

CD6 cells Reimbursement with leading centers Overall market opportunity Clinical design and timeline EQ001 Opportunity Set Therapeutic Scientific Translational Commercial Therapeutic Area Clinical Plan Indication Rationale

Research Opportunity aGVHD Transplant Science cGVHD Pulmonary severe asthma Systemic systemic lupus Autoimmunity scleroderma Crohn's Gastrointestinal colitis multiple sclerosis Neuroinflammation neuromyelitis optica 14 Key Selection

GVHD Remains an Area of High Unmet Medical Need aGVHD ~50% of HSCT

Steroids remain SOC for cGVHD first-line treatment of ~30-70% of HSCT aGVHD and cGVHD Bronchiolitis Obliterans Mortality from aGVHD as Advanced aGVHD skin Advanced aGVHD Gut of the Lung in cGVHD high as 95% in steroid refractory patients cGVHD is

the leading cause of non-relapse mortality in patients surviving more than 2 years 15GVHD Remains an Area of High Unmet Medical Need aGVHD ~50% of HSCT Steroids remain SOC for cGVHD first-line treatment of ~30-70% of HSCT aGVHD and cGVHD

Bronchiolitis Obliterans Mortality from aGVHD as Advanced aGVHD skin Advanced aGVHD Gut of the Lung in cGVHD high as 95% in steroid refractory patients cGVHD is the leading cause of non-relapse mortality in patients surviving more than 2 years

GVHD is a Significant & Growing Market Opportunity Projected US

aGVHD incidence and GVHD prevalence by the year 2025 Annual incidence of aGVHD up to 6,000 Total prevalence of GVHD up to 35,000 Currently, limited available FDA approved therapies Significant need for safe and effective

therapies No products approved for aGVHD Ibrutinib approved 2nd/3rd line for More than 8,500 allogeneic transplants in 2016 cGVHD 4% annual growth rate since 2007 16GVHD is a Significant & Growing Market Opportunity Projected US

aGVHD incidence and GVHD prevalence by the year 2025 Annual incidence of aGVHD up to 6,000 Total prevalence of GVHD up to 35,000 Currently, limited available FDA approved therapies Significant need for safe and effective

therapies No products approved for aGVHD Ibrutinib approved 2nd/3rd line for More than 8,500 allogeneic transplants in 2016 cGVHD 4% annual growth rate since 2007 16

CD6 Plays a Central Role in GVHD Autoreactive T cells drive

tissue damage in GVHD eff T cells overexpress CD6 eff CD6 co-stimulation results in increased T cell activation, eff proliferation and increased secretion of pro-inflammatory cytokines including IFN- , TNF- , IL-6 and IL-17