This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "may," "will," "should," "expect," "plan," "anticipate," "target," and simil

Uniquely Powerful Approaches to Tackling the Toughest Diseases SELECTIVE TARGETS. BROAD IMPACT. Kezar Life Sciences

This presentation contains forward-looking statements within the meaning of the Private Securities Litigation Reform Act of 1995. Words such as "may," "will," "should," "expect," "plan," "anticipate," "target," and similar expressions (as well as other words or expressions referencing future events or circumstances) are intended to identify forward-looking statements. Each of these forward-looking statements involves substantial risks and uncertainties that could cause actual results to differ significantly from those expressed or implied by such forward-looking statements. Forward-looking statements contained in this presentation include, but are not limited to, statements about the company's financial position and cash runway, statements about the potential use of our product candidates to treat patients, the association of data with treatment outcomes, the design, timing and progress of clinical trials, the expected timing of data disclosures, the likelihood that data, including interim or topline data, will support future development, the likelihood of obtaining regulatory approval for our product candidates, and the regulatory pathway and competitive landscape for our product candidates.

Data from the MISSION Phase 2 clinical trial are preliminary and will require confirmation in additional patients as well as longer follow-up to draw any clinical conclusions. Interim top-line data and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data.

Forward-looking statements in this presentation reflect Kezar's current beliefs and expectations. Many factors may cause differences between current expectations and actual results, including the availability of additional data, confirmation of data resulting from trial auditing and verification procedures, unexpected safety or efficacy data observed during preclinical or clinical studies, upon study completion, clinical trial enrollment rates that are lower than expected, changes in expected or existing competition, and changes in the regulatory environment. Other factors that may cause our actual results to differ from current expectations are discussed in Kezar's most recent Form 10-K or Form 10-Q filed with the U.S. Securities and Exchange Commission (SEC), under the caption "Risk Factors" and elsewhere in such reports. Except as required by law, we assume no obligation to update any forward-looking statements contained herein to reflect any change in expectations, even as new information becomes available.

Forward-Looking Statements and Interim Data Disclaimer 2

Analyst Day Agenda 3

The Kezar Opportunity: Harnessing Master Regulators of Cellular Function to Tackle Immune-mediated Diseases and Cancer A novel approach to harmonizing the immune system via immunomodulation; Potential to be a pipeline in a drug First in class agent with broad anti-tumor activity; Potential to inhibit multiple targets with a single small molecule Builds on 10+ years of R&D work in proteasome biology and protein secretion led by Kezar's Scientific Co-founders, Chris Kirk & Jack Taunton $121M cash, cash equivalents, and marketable securities;

48.6M common shares outstanding; recent credit facility extends runway 4

Kezar's Novel, Complementary Programs Target Master Regulators of Cellular Function to Achieve Broad Therapeutic Activity Modulates multiple drivers of inflammation

Restores normal immune responses, without evidence of immunosuppression

PROTEIN DEGRADATION:

The Immunoproteasome PROTEIN SECRETION:

The Sec61 Translocon N Broad anti-tumor activity in preclinical models

Applications in oncology, immuno-oncology, and autoimmunity

Potential for small molecules to replace certain biologics

Potential to restore normal immune responses while avoiding immunosuppression

Modulates multiple drivers of inflammation across immune cell types

Avoids cytopenias; favorable safety profile for chronic use based on Phase 1 studies

Active in broad array of autoimmune disease models

Immunoproteasome Inhibition is a powerful, differentiated mechanism broadly applicable across the autoimmune landscape 1Johnson et al. J. Med Chem 201; Potent and selective inhibitor of immunoproteasome-specific subunits LMP7 and LMP21 KZR-616 6

Inflammatory Disorders are Currently Treated One Cytokine or Cell at a Time, but the Inhibition of Immunoproteasome with KZR-616 Targets Them All Macrophages

Monocytes T-cell B-cell Rituxan/Gazyva

IVIg/FcRn Inhibitor Orencia

IL-17 Cosentyx/Taltz KZR-616 7

Our Clinical Programs Inhibit Multiple Drivers of Disease via Selective Targets to Address a Diverse Pipeline of Indications 8

Noreen R. Henig, MD Chief Medical Officer MISSION: Phase 1b/2 Study to Evaluate

the Safety and Efficacy of KZR-616 in Systemic Lupus Erythematosus/Lupus Nephritis 9 Interim data reported and are subject to audit and verification procedures that could result in material changes in the final data.

KZR-616 Clinical Program Overview Abbreviations: DM, dermatomyositis; LN, lupus nephritis; PM, polymyositis; SLE, systemic lupus erythematosus. 10

MISSION: Phase 1b/2 Open-Label, Multi Center Study to Evaluate the Safety and Efficacy of KZR-616 in SLE/LN Part 1: Phase 1b Part 2: Phase 2 Abbreviations: CRR, complete renal response; LN, lupus nephritis; PD, pharmacodynamics; PK, pharmacokinetics; PRO, patient reported outcomes; PRR, partial renal response; QW, every week; SLE, systemic lupus erythematosus.

Modulates innate and acquired immune responses without signs of immunosuppression to date

Weekly administration results in consistent pharmacokinetics and pharmacodynamics

Selective inhibition of the immunoproteasome via targeting of specific subunits LMP2 and LMP7

Weekly dose leads to consistent exposure and clearance (T1/2 <5 hours)

Not predicted to result in clinically significant DDI

Demonstrates rapid and sustained immunomodulatory gene expression changes

Favorable safety and tolerability profile

Improved signs and symptoms of SLE and LN as measured with exploratory endpoints in symptoms, serologic markers, reduction in proteinuria, and reduction in markers of specific kidney inflammation KZR-616: Phase 1 Findings to Date Well-Positioned to Be Chronic Therapy for Autoimmune Diseases Abbreviations: DDI, drug-drug interactions; SLE, systemic lupus erythematosus; LN, lupus nephritis.

Furie et al, EULAR 2021 and Data on File. 12

MISSION Phase 1b [Complete]: Safety and Tolerability Supports Extended Use in Chronic Diseases *Cohorts 2b, 2c, and 3 received a lyophilized formulation of KZR-616.

Furie et al, EULAR 2021.

Abbreviations: d/c, discontinuation; TEAE, treatment-emergent adverse event. 13

MISSION Phase 1b [Complete]: Reduced UPCR and uCD163* in 2 of 2 Patients With LN Baseline stable treatment regimen of leflunomide, hydroxychloroquine, and prednisone (10 mg/d); failed prior tacrolimus

>50% reduction in UPCR at week 17

Reduced anti-dsDNA at week 13 Baseline stable treatment regimen of MMF (2 g), hydroxychloroquine, and prednisone (10 mg/d)

>50% reduction in UPCR at week 5

Improved symptom scores at week 5

Reduced anti-dsDNA at week 5 *uCD163 - novel noninvasive biomarker that correlates with active LN inflammation and shows moderate concordance with UPCR; normalized to urine creatinine. 14

Interim Data MISSION Phase 2 Data from the MISSION Phase 2 clinical trial are preliminary and will require confirmation in additional patients as well as longer follow-up to draw any clinical conclusion. Interim top-line and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data. 15

*Patients received 24 weeks of KZR-616; End of treatment assessments performed at Week 25.

Abbreviations: UPCR, urine protein to creatinine ratio; CRR, complete renal response; EOT, end of treatment; PRR, partial renal response; PRO, patient reported outcomes; SC, subcutaneous; QW, every week. MISSION Phase 2:

Open-Label Study to Evaluate the Efficacy and Safety of KZR-616 in Patients with Active Proliferative Lupus Nephritis https://clinicaltrials.gov/ct2/show/NCT03393013 Week 25

End of Treatment (EOT)* Adult patients

with LN^ (n=20) ^LN patients (Class III or IV +/- Class V) with significant proteinuria (UPCR 1.0 measured in 24-hour urine collection) despite standard therapy Safety assessment to continue up to 12 weeks 1st dose is 30mg KZR-616 60 mg SC QW

Added to stable background therapy

[No SoC induction therapy] Patients in MISSION Phase 2 do not receive high doses of MMF or corticosteroids at the start of the study.

Lack of "induction" therapy is a significant difference compared to recently published trials in LN 16

Open-label study evaluating KZR-616 60mg weekly for 24 weeks in patients with active, proliferative lupus nephritis (LN, Class III or IV, +/- V)

Primary endpoint: Number of patients with 50% reduction in UPCR compared to baseline after 24 weeks of KZR-616

Key secondary endpoints:

Safety and tolerability of KZR 616

The number of patients with a complete renal response (CRR) and partial renal response (PRR) after 24 weeks of treatment as defined by:

MISSION Phase 2: Endpoints PRR:

50% reduction in UPCR and/or UPCR <1 (if baseline UPCR <3) or UPCR <3 (if baseline UPCR >3)

eGFR 60 mL/min/1.73m2 or no worsening of eGFR from baseline of 25%

No use of prohibited medication CRR:

eGFR 60 mL/min/1.73m2 or no worsening of eGFR from baseline of 25%

Prednisone (or equivalent) 10 mg

No use of prohibited medication Abbreviations: UPCR, urine protein to creatinine ratio; CRR, complete renal response; PRR, partial renal response. For MISSION interim data, CRR and PRR were calculated using absolute UPCR values and not percentages 17

Target enrollment of 20 patients met for MISSION Phase 2 study

Interim analysis is based on laboratory and safety analysis; a full data analysis will occur at the completion of the study

10 patients who completed at least 13 weeks of treatment with KZR-616 SC QW were included in the analysis

5 of the 10 patients reached EOT (W25) at the time of the interim analysis

Patients did not receive induction therapy, and there was no mandated taper of glucocorticoids or other agents.

Patients included in the interim analysis participated from 4 countries [US, Australia, Russia and Ukraine]

Abbreviation: EOT, end of treatment; SC, subcutaneous; QW, once weekly. Patients received 24 weeks of KZR-616; end of treatment assessments performed at Week 25 Data from the MISSION Phase 2 clinical trial are preliminary and will require confirmation in additional patients as well as longer follow-up to draw any clinical conclusion. Interim top-line and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data. MISSION Phase 2: KZR-616 for the Treatment of LN Interim Data Overview 18

KZR-616 demonstrates a safety and tolerability profile favorable for long-term administration

4 of 5 patients completing end of treatment (Week 25) demonstrated clinically meaningful reduction in proteinuria:

2 patients with CRR (complete renal response)

2 patients with PRR (partial renal response)

MISSION Phase 2 [Interim Data]: KZR-616 60mg SC QW is Associated with Clinically Important Renal Response 19 Data from the MISSION Phase 2 clinical trial are preliminary and will require confirmation in additional patients as well as longer follow-up to draw any clinical conclusion. Interim top-line and preliminary data from our clinical trials that we announce or publish from time to time may change as more patient data become available and are subject to audit and verification procedures that could result in material changes in the final data. CRR and PRR based on absolute UPCR values

MISSION Phase 2 [Interim Data]: Patient Disposition Weeks EOT^ n=5 W13

n=10 Patients* *Each bar represents one patient in the study.

^Patients received 24 weeks of KZR-616; end of treatment assessments performed at Week 25. 20 Interim data reported as of 01-Oct 2021 and are subject to audit and verification procedures that could result in material changes in the final data.

MISSION Phase 2 [Interim Data]: Key Demographics and Baseline Characteristics of 10 Patients Who Reached 13 Weeks Abbreviations: MMF, mycophenolate mofetil; MPA, mycophenolic acid. 21 Interim data reported as of 01-Oct 2021 and are subject to audit and verification procedures that could result in material changes in the final data.

MISSION Phase 2 [Interim Data]: Overall Renal Response in 4 out of 5 Patients at EOT (n=5) 22 Interim lab data reported as of 12-Oct 2021 and are subject to audit and verification procedures that could result in material changes in the final data. Patients received 24 weeks of KZR-616; end of treatment assessments performed at Week 25.

MISSION Phase 2 [Interim Data]: 3 out of 5 Patients Achieved 50% Reduction in UPCR at EOT 23 * UPCR reduction

25% to <50% UPCR reduction

50% *n=5 patients with 25 weeks data; patients received 24 weeks of KZR-616; end of treatment assessments performed at Week 25.

Abbreviation: EOT, end of treatment. All patients at EOT were on same or reduced dose of glucocorticoids

from study start to EOT Interim lab data reported as of 12-Oct 2021 and are subject to audit and verification procedures that could result in material changes in the final data.

MISSION Phase 2 [Interim Data]: KZR-616 Showed Early, Meaningful Reduction in UPCR at Week 13 * UPCR reduction

25% to <50% UPCR reduction

>0% to <25% *N=10 patients with 13 weeks data. 24 Interim lab data reported as of 12-Oct 2021 and are subject to audit and verification procedures that could result in material changes in the final data.

No abnormal disease biomarkers, including cell counts, emerged in patients on study

MISSION Phase 2 [Interim Data]: Improvement in Key Serologic Biomarkers Observed at Week 13 in Patients with Abnormal Levels at Baseline 25 Week 25 data pending.

Reference ranges: dsDNA <20 IU/mL; C3 90 - 180 mg/dL; C4 10 - 40 mg/dL. Interim lab data reported as of 12-Oct 2021 and are subject to audit and verification procedures that could result in material changes in the final data.

All reported AEs were mild to moderate ( Grade 2) except

1 related SAE of Grade 3 migraine occurred, which led to temporary interruption of study drug. Patient fully recovered and resumed study treatment at the same 60mg dose level.

1 unrelated SAE of worsening PAH and AKI; led to discontinuation

No study discontinuations due to related AEs