Innovative Therapeutics For Respiratory Health

Investor Presentation 2Q-2021

1 Forward Looking Statement

These forward-looking statements relate to future events or future financial performance of the We operate in a very competitive and rapidly changing environment. New risks emerge from time to Company. All such forward-looking statements involve risks and uncertainties and are not guaranties time. It is not possible for our management to predict all risks, nor can we assess the impact of all of future performance. An investment in the securities of Aridis is speculative in nature, involves a factors on our business or the extent to which any factor, or combination of factors, may cause actual high degree of risk, and should not be made by an investor who cannot bear the economic risk of its results to differ materially from those contained in any forward-looking statements we may make. In investment for an indefinite period of time and who cannot afford the loss of its entire investment. light of these risks, uncertainties and assumptions, the forward-looking events and circumstances These include many important factors that affect our ability to achieve our stated objectives including, discussed in this presentation may not occur and actual results could differ materially and adversely but not limited to: from those anticipated or implied in the forward-looking statements.

* The timing of regulatory submissions; Except as required by law, neither we nor any other person assumes responsibility for the accuracy * Our ability to obtain and maintain regulatory approval of our existing product candidates and any and completeness of the forward-looking statements. We undertake no obligation to update publicly other product candidates we may develop, and the labeling under any approval we may obtain; any forward-looking statements for any reason after the date of this presentation to conform these * Approvals for clinical trials may be delayed or withheld by regulatory agencies; statements to actual results or to changes in our expectations. * Pre-clinical and clinical studies will not be successful or confirm earlier results or meet expecta- tions or meet regulatory requirements or meet performance thresholds for commercial success; We have filed a registration statement (including a prospectus) with the Securities and Exchange * The timing and costs of clinical trials, the timing and costs of other expenses; Commission ("SEC") for the offering to which this communication relates. Before you invest, you * Our ability to obtain funding from third parties; should read the prospectus in the registration statement and other documents we have filed with the * Management and employee operations and execution risks; SEC for more complete information about us and this offering. You may get these documents for free * Loss of key personnel; by visiting EDGAR on the SEC web site at http://www.sec.gov. Alternatively, we, any underwriter, or * Competition; any dealer participating in the offering will arrange to send you the prospectus if you request it from * Market acceptance of products; Cantor Fitzgerald & Co., Attention: Capital Markets, 499 Park Avenue, 6th Floor, New York, NY * Intellectual property risks; 10022; email: [email protected]. This presentation shall not constitute an offer to sell or the * Assumptions regarding the size of the available market, benefits of our products, product pricing, solicitation of an offer to buy these securities, nor shall there be any sale of these securities in any timing of product launches; state or jurisdiction in which such offer, solicitation, or sale would be unlawful prior to registration or * The uncertainty of future financial results; qualification under the securities laws of any such state or jurisdiction. * Risks associated with this offering; * Our ability to attract collaborators and partners; * Our reliance on third party organizations.

2 Product Pipeline

Next Products Targets Pre-Clinical IND Phase 1 Phase 2 Phase 3 Milestone

AR-301 mAb Gram (+) Bacteria Interim Futility Pneumonia & Blood Stream Infections (Salvecin) S. aureus a-toxin data 2H2021

AR-101 mAb Gram (-) Bacteria Phase 2/3 (Aerumab) P. aeruginosa LPS O11 HAP/VAP tbd

AR-501 Gram (-) & (+) Cystic Fibrosis Phase 2a data (Panaecin) Iron Acquisition Systems 2H2021

AR-712 mAb COVID-19 Phase 1/2 COVID-19 AR-701 RBD mAb 2H2021

tbd AR-401 mAb Gram (-) Bacteria Bacteremia A. baumannii

3 Using Human Monoclonal Antibody for Infections

mAb Toxins Monoclonal Antibody (mAb)

Antibiotics

Bacteria Virus

4 Y

TM PEX Monoclonal Antibody Discovery and Production Platform Technology

CRISPR

Guided Integration Y

Convalescent PEXTM Nanoarrays B-cell Cloned CDRs B.R.E.A.T.H. TM GMP COVID-19 patient B-cell Selected or H&L of IgG’s CHO cell line Manufacturing repertoire screening

Y PEXY TM Discovery, Development, and Manuf. 12-15 months time saving

TRADITIONAL: Discovery, Development, and Manufacturing

0 3 6 9 12 15 18 21 24 27

Months

5 Healthcare Burden: S. aureus and P. aeruginosa Bacteria

~252,000 ICU patients US claims database (2018) n=201 n=394 Survey of 30 cases (median) Hospital Days In-Patient Costs Hospital 44.4% $213,104 60 days 55.4 $220,000 Pharmacy 21.0% Laboratory 16.3% 37.9 $146,978 40 days Respiratory Treatment (Mech. ventilation) 9.3% $110,000 Radiology (+CT Scans) 3.3% 20 days Cardiology 1.9% $33,851 7.2 Operating Room 1.4%

Control Staph Pseudomonas Control Staph Pseudomonas Diagnostics (Blood ECG) 1.9% Pulmonary Diagnostic 0.4% ICU stay 1.1 day 6.9 days 14.8 days 1.1 day 6.9 days 14.8 days Orthopeadic 0.3% All Cause 3% 16% 20% 3% 16% 20% Mortality Restrepo (2010) ICHE 31:509-515

Kyaw MH et al., 2015 BMC Health Serv Res. 15:241 6 Interstitium Normal Alveolus AR-301 Mechanism of Action:

Alveolar Type 1 cells air space Targets S. aureus α-Toxin Staphylococcus aureus Macrophages α-toxins Anti-toxin monoclonal mAb antibody approach is a PMN Necrosis proven MOA, e.g.

α-toxins attacking α-toxins immune cell Commercialized Intact Immune Cell Anthrax mAb Raxibacumab (GSK-EBSI)

Under development S. Aureus mAb MEDI4893 (AZN)

Gram (+) bacteria: S. aureus Host cells killed by α-toxins Red blood cells T-cells Neutrophils Pneumoncytes Macrophages, Monocytes Endothelial cells Toxins 2013, 5(6), 1140-1166

7 Therapeutic Treatment in Acute Pneumonia Setting Superiority Trial Design

Antibiotics-alone Adjunct therapy VS. Standard Standard AR-301 of Care of Care

With positive data, provides for value-based premium reimbursement

8 AR-301 Phase 2: Trial Recently Completed

Design Randomized, double-blind, placebo-controlled, single ascending dose of AR-301 31 sites across EU and U.S.

Patient Selection 48 patients with HAP or VAP caused by S. aureus

Groups SOC [antibiotics alone] + Placebo n=16 SOC + AR-301 (1 mg/kg ) n= 6 SOC + AR-301 (3 mg/kg) n= 8 SOC + AR-301 (10 mg/kg) n=10 SOC + AR-301 (20 mg/kg) n= 8

Primary Endpoint Safety and pharmacokinetics

Secondary Endpoint Time to removal of ventilator (VAP patients) Hospitalization days Microbiological cure All-cause mortality Shorter time to eradication Clinical cure rate Days in ICU

Francois, B. et al. 2018 Intensive Care Medicine Data trend in favor of adjunctive treatment benefit

9 AR-301: Favorable Phase 2 Safety & PK Data

Adjunctive AR-301 treated groups were well

600 (plasma half-life of 23-31 days) ug/mL antibiotics alone (placebo) group (n=48).

ation AR-301 Few adverse events (AEs) deemed related to 400 ent r 20 mg/kg ug/mL AR-301 (2.8%). on c 50% (half-life mark) No serious adverse events (SAEs) related to 200 AR-301. ug/mL lasma C Antibiotic Deaths were deemed unrelated to AR-301 Half Life treatment (n=6). Mean P 0 ug/mL 24 48 72 96 120 144 168 (hours) Time since start of infusion

10 100% Antibiotics alone (n=5) Phase 2

tion 80% eiving Aggregated AR-301 treated VAP groups til a e c

e n 60% exhibited lower probability of requiring V 50% y of R improvement mechanical ventilation vs. placebo. 40% obabili t echanical r

P M 20% +AR-301 Pooled (n=20)

0 5 10 15 20 25 Days on Mechanical Ventilators

Francois, B. et al. 2018 Intensive Care Medicine.

11 AR-301 Phase 3: Trial Design

1-to-1 randomized, double-blind, Broad spectrum placebo-controlled, single infusion antibiotics dose IV infusion Enrolling 240 patients with VAP caused by S. aureus across 125 sites in 20 n = 120 Day 21 countries (U.S., EU, Asia) Randomize Test of Evaluating the potential of & Treat Clinical adjunctive AR-301 (20 mg/kg) Cure to SOC antibiotics vs. n = 120 antibiotics alone Primary endpoint of clinical cure rate at day 21

Interim futility analysis of 120 patients Broad in 2H2021 and final data AR-301 at 20 mg/kg spectrum IV infusion readout in 1H2022 antibiotics

(ClinicalTrials.gov ID NCT03027609)

12 AR-301 Phase 3 Study Powering Calculation and Assumptions

Primary Endpoint: Clinical Cure Rate

Study Control AR-301 Absolute Evaluable Total Power (SOC)* + SOC ** per group Enrolled 80% 75% 95% 20% n = 55 n = 110 90% 75% 95% 20% n = 69 n = 138

n = 240 enrollment target ** Rationale for 20% absolute over-powered to achieve clinical cure rate improvement setting superior clinical cure rate Considered clinically meaningful to physicians

p<0.05 Ph2a data showed trend toward improvements in shorter ventilation time & microbiological eradication (i.e. 2 of the 3 components of the primary endpoint)

13 $6 Billion Market for (AR-301): VAP, HAP Gram (+) Staphylococcus aureus-Induced HAP/VAP

Estimated $6 billion annual healthcare cost burden attributable to S. aureus nosocomial pneumonia 395,000 Patients in the US, Japan, EU

Breakdown MRSA 52% of Strains MSSA 48%

Potential S. aureus HAP/VAP Patients by Market Sources

1 DR/Decision Resources, LLC. 2016; 2 Chastre J, and Fagon J-Y, Ventilator-associated pneumonia, State U.S.A. 251,600 of the Art, Am J Respir Critical Care Med, 2002 (165): 867-903. 3 Warren DK, Outcome and Attributable Cost of VAP among ICU Japan 90,000 patients in a suburban medical center, Critical Care Med 2003;31(5):1312-7.

Europe 53,700

Lifecycle opportunities include surgical site, skin/skin structure, UTI, and BSI infections due to S. aureus

14 Pneumonia caused by MRSA

AR-301 Product Contribution $1,000

$800 Key Assumptions

enses) First-line adjunctive treatment MRSA only HAP / VAP / HCAP $600 60% marketshare US / EU / Japan et of Ex p $400 $10,500 per course

illion ( N $200 $ M

$00 2019 2020 2021 2022 2023 2024 2025 2026 2027 2028 2029 2030 2031 2032 2033 2034 1st Phase 3 2nd Phase 3 BLA & Launch

SOC antibiotics in HAP/VAP: Avycaz / ceftazidime/avibactam (AstraZeneca): $13,764 (14 days course) Vibativ/ Telavancin (Astellas): $8,841 (21 days course)

15 AR-301 Data: Proxy Data from AZN’s Suvratoxumab Pre-Emptive Treatment In S. Aureus Colonized Patients Also Show Evidence of Clinical Benefits

AstraZeneca’s Suvratoxumab AR-301 Prophylactic Pre-emptive Treatment for Acute At-risk (non-infected) Lung colonized, High risk Full-on lung infection Asymptomatic Asymptomatic Ventilator-assoc. pneumonia

Phase 2 Results (n=196)*: Phase 3 (n = 240) Decreased risk of VAP 32% [data 1H2022] Decreased risk of VAP 47% (<65 yrs old)

*Francois, B. et al. 2021 Lancet Infectious Diseases

16 AR-501: Novel Inhaled Non-Antibiotic Small Molecule Anti-infective

Mechanism of Action Iron (Fe) is necessary for bacterial metabolic functions. AR-501 (gallium, Ga) replaces Fe

Ga Gallium

AR-501 impairs mulitple bacterial functions

Standard antibiotics inhibit single targets

17 AR-501 Phase 1/2: Healthy & Cystic Fibrosis Patients CF Foundation Funded

Phase 1 Healthy Volunteers PARI eFlow Phase 2 Cystic Fibrosis Patients nebulizer (on-going) (1H-2019) Single Ascending Dose Done

6 mg 20 mg 40 mg (2H-2021) Multiple Ascending Doses

18 patients 6 patients t = 0, 1, 2 weeks AR-501 Placebo Primary Endpoint: 6 mg 20 mg 40 mg Safety and PK 30 patients 15 patients Secondary Endpoints: AR-501 Placebo (1H-2020) Multiple Ascending Doses Done Lung function of CF patients t = 0, 1, 2, 3, 4 weeks (changes in FEV1) 6 mg 20 mg 40 mg Sputum bacteriology Data Readout: 18 patients 6 patients Phase 2a CF subjects in 2H2021 AR-501 Placebo Ph1 study results: AR-501 was well tolerated

18 A single IV dose of gallium resulted in statistical significant improvement in lung infection

Proxy Data: 10% Intent to Treat Population CF Patients 8% Safety & Efficacy (L) Inhaled V 6% of IV Gallium 4% e Change mg/mL Gallium Demonstrated Delivery ti v 2% el a 0% Placebo 300 -2% om Baseline F E ean R f r

M -4% t ra tion -6% e n 1 6 14 28 56 on c

Day Days Days Days Days .)

Gallium 60 60 58 60 59 es t

Placebo 59 57 57 56 56 d (

Patients Patients Patients Patients Patients Sputum c 2 IV Inhal e Data from University of Washington: Goss, C. et al. 2018 N. Am. Cystic Fibrosis Conference Abstract #307 (*estimate based on animal PK data)

19 AR-712: Inhaled COVID-19 mAb Program

Highly potent SARS-CoV-2 fully human mAbs from convalescent COVID-19 patients - Proprietary stable inhaled formulation designed for direct lung delivery - Therapeutically eradicated SARS-CoV-2 at ultra low dose (~0.05 mg/kg) in animal challenge model - Up to year-long protection (engineered for plasma half-life extension) - Engineered removal of antibody disease enhancement (ADE) risk

AR-712 in-human dosing is the lowest vs. all competitors*

AR-712 two mAbs cocktail bind to COVID’s AR-712 2 - 6 mg (est) spike protein, blocking COVID & its LLY (CoV555) 700 to 7,500 mg >1,000x variants* from being able to bind to the host cell. REGN (10933/10987) 2,400 to 8,000 mg

*Scaling to human dose based on animal SARS-CoV-2 challenge study. See https://www.biorxiv.org/content/10.1101/2020.10.14.339150v1 *UK, So. Africa, Brazil, Japan SARS-CoV-2 strains 20 AR-712: Inhaled COVID-19 mAb Program

Convenient self-dosing in-home

Target Populations - Designed to lower the barrier to COVID-19 treatment in outpatients - Treatment mild to moderate COVID-19 non-hospitalized patients - Prophylaxis [elderly, high risk frontline workers, etc]

Phase 1/2 in 2H21

Phase 3 data in 2022

https://www.biorxiv.org/content/10.1101/2020.10.14.339150v1.

21 Key Milestones

2021 2022

Phase 3 Phase 3 AR-301 Interim Futility Full Data Toxin Blocker

AR-101 Phase 2/3 Immune Modulation T.B.D.

AR-501 Phase 2a Phase 2b Cystic Fibrosis Full Data Full Data

AR-712 IND Ph1/2 Ph3 COVID-19 Enabling

22 Senior Management

Vu Truong Hasan Jafri CEO, Director Chief Medical O cer (Formerly Medimmune, Aviron) (Formerly AstraZeneca/Medimmune)

Fred Kurland Steve Chamow Chief Financial O cer VP, Development (Formerly Coherus, intekrin) (Formerly Genentech, Abgenix)

Elizabeth Leininger Lynne Deans VP, Regulatory & Quality VP, Clinical Operations (Formerly FDA, Novartis) (Formerly Roche, Dermira)

23 Board of Directors

Eric Patzer, Ph.D. Robert Ru olo, Ph.D., D.Sc. Director, Chairman Director (Co-Founder, Aridis) (Former President Wyeth/Pzer)

Vu Truong, Ph.D. Craig Gibbs, Ph.D., M.B.A. Director Director (CEO, Aridis) (Commercial Gilead; Genentech)

Susan Windham-Bannister, Ph.D. John Hamilton, M.B.A. Director Director (Assoc. Women in STEM, Mass. Life Sci. Ctr) (CFO, Depomed; BioMarin)

24 Financial Information

Three Months Ended Condensed Consolidated Statement of Operations 03/31/2021 ($ in 000’s) Analyst Coverage ($11 - $22 PT) Total revenue $0 - Cantor Fitzgerald (Louise Chen) Research and development $4,955 - HC Wainwright (Vernon Bernadino) General and administrative $1,944 - ROTH Capital (Jonathan Aschoff) Loss from operations $( 6,899) Net loss $( 6,891) - Maxim Group (Jason MacCarthy) As of - Northland Securities (Carl Byrnes) Balance Sheet Mar. 31st, 2021 - Laidlaw (Frank Brisebois) Cash and cash equivalents $10,472 Common stock: 100,000,000 shares authorized; 11,232,921 shares issued and outstanding as of March 31st, 2021

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