XBiotech Harnessing Natural Immunity to Transform Medicine A platform overview and review of recent findings in dermatology

FORWARD LOOKING STATEMENT This presentation contains forward-looking statements, including declarations regarding management's beliefs and expectations that involve substantial risks and uncertainties. In some cases, you can identify forward-looking statements by terminology such as "may," "will," "should," "would," "could," "expects," "plans," "contemplate," "anticipates," "believes," "estimates," "predicts," "projects," "intend" or "continue" or the negative of such terms or other comparable terminology, although not all forward- looking statements contain these identifying words. Forward-looking statements are subject to inherent risks and uncertainties in predicting future results and conditions that could cause the actual results to differ materially from those projected in these forward-looking statements. These risks and uncertainties are subject to the disclosures set forth in the "Risk Factors" section of certain of our SEC filings. Forward-looking statements are not guarantees of future performance, and our actual results of operations, financial condition and liquidity, and the development of the industry in which we operate, may differ materially from the forward-looking statements contained in this presentation. Any forward-looking statements that we make in this presentation speak only as of the date of this presentation. We assume no obligation to update our forward-looking statements whether as a result of new information, future events or otherwise, after the date of this presentation.

XBiotech Manufacturing & R&D Center

Mine the Human Antibody Repertoire Healthy Human Volunteers with Natural Immunity to Disease …And We Develop the Best that the Human Antibody Repertoire has to Offer 4

Opportunities Skin Disease (ie. Inflammatory disease) Cardiovascular Disease Infectious Disease Cancer Acute Infectious Outbreaks 5

Innovations for Antibody Discovery Precision High Throughput Screen of Antibody Drug Candidates in Human Blood Flow Cytometry Based, Epitope Driven Antibody Identification Rapidly Identify Rare Antibody Genes from Blood Comprehensive Repertoire and Inclusive Variable Region Cloning Innovations for Antibody Discovery 6

Simplicity—Reduced Plant & Equipment Infrastructure Flexibility—modular, scalable Capital Sparing Compliant—disposable Reducing the Cost Barrier for Commercialization: Manufacturing Innovation

XBiotech designed and engineered manufacturing technology 8

250 Issued and Pending Patents World-Wide

Pipeline Treatment Area Indication Discovery/Pre-Clinical Phase I Phase II Phase III Dermatology Atopic Dermatitis Hidradenitis Suppurativa Acne Vulgaris Plaque Psoriasis Pyoderma Gangrenosum Systemic Scleroderma Oncology Pancreatic Cancer Symptomatic / Advanced Colorectal Cancer Palliative Care Endocrine Type II Diabetes Anti-Infective Staphylococcus Aureus (514G3) Clostridium Difficile (CDX-1) Varicella Zoster (VZX) Influenza (HAN-X) Bermekimab

Targeting a Master Regulator of Inflammation Interleukin-1a

Bermekimab: a new kind of antibody First-In-Class (only antibody therapy derived from human) Derived from a Natural Human Response—NOT animal derived or so called “fully human” No engineering of antibody binding Naturally neutralizes Interleukin-1a—the master regulator of inflammation

Bermekimab Clinical Studies in Dermatology Indications Hidradenitis Suppurativa (DBPCRS intravenous) Hidradenitis Suppurativa (POC s.c.) Plaque Psoriasis (POC s.c.) Acne Vulgaris (POC s.c.) Atopic Dermatitis (POC s.c.) DBPCRS = Double blind placebo controlled randomized study POC = Proof of concept clinical study s.c. = subcutaneous

XBiotech’s Published Primary Clinical Research for Bermekimab in Dermatology Bermekimab Targeting Interleukin-1Alpha for Moderate to Severe Hidradenitis Suppurativa not Eligible for Adalimumab: A Randomized Study Kanni T, Argyropoulou M, Spyridopoulos T, Pistiki A, Stecher M, Dinarello CA, Simard J, Giamarellos-Bourboulis EJ. J Invest Dermatol. 2018 Apr;138(4):795-801 Open-label trial of Bermekimab, a true human monoclonal antibody targeting interleukin 1α, for the treatment of psoriasis Coleman KM, Gudjonsson JE, Stecher M. JAMA Dermatol. 2015 May;151(5):555-6. An open label, phase 2 study of Bermekimab monotherapy for the treatment of acne vulgaris and psychiatric comorbidity Carrasco D, Stecher M, Lefebvre GC, Logan AC, Moy R. J Drugs Dermatol. 2015 Jun;14(6):560-4.

Recent Reviews for Bermekimab in Dermatology Investigational Drugs in Clinical Trials for Hidradenitis Suppurativa Peter Theut Riis, Linnea R. Thorlacius & Gregor B. Jemec. Expert Opinion on Investigational Drugs. 2018 Jan;27(1):43-53. The Role of Interleukin‐1 in Inflammatory and Malignant Human Skin Diseases and the Rationale for Targeting Interleukin‐1 Alpha Mayassa J. Bou-Dargham et al., Med Res Rev. 2017 Jan;37(1):180-216.

Hidradenitis Suppurativa Bermekimab, an Anti-IL-1α Monoclonal Antibody, Shows Efficacy for Treating Hidradenitis Suppurativa (HS) with Breakthrough Reduction in Pain Hidradenitis Suppurativa Data Presented at the American Academy of Dermatology, March 2019 Alice Bendix Gottlieb MD, PhD Clinical Professor of Dermatology Icahn School of Medicine at Mount Sinai New York, NY 16

Phase II Open Label, Study of Bermekimab in Patients with Moderate to Severe Hidradenitis Suppurativa Week 0 Week 12 Patients who have previously failed anti-TNF Therapy (“Failures”) 400mg Every Week (n=24) Baseline Data 1st Injection Endpoint Data After 12 injections Week 0 Week 12 Patients with no prior treatment with anti-TNF Therapy (”Naïve”) 400mg Every Week (n=18) Baseline Data 1st Injection Endpoint Data After 12 injections

Bermekimab vs Humira Positive HiSCR at week 12 Subjects Achieved % p=0.003 p<0.001 PIONEER I * * Humira Humira + Oral antibiotics N=24 N=18 *Source: N Engl J Med. 2016 Aug 4;375(5):422-34. doi: 10.1056/NEJMoa1504370. Two Phase 3 Trials of Adalimumab for Hidradenitis Suppurativa. https://www.ncbi.nlm.nih.gov/pubmed/27518661 18

Bermekimab vs Humira Patients with total abscess and inflammatory-nodule count of 0, 1, or 2 at week 12 Subjects Achieved % * * Humira + Oral antibiotics Humira N=24 N=18 p=0.961 p=0.010 *Source: N Engl J Med. 2016 Aug 4;375(5):422-34. doi: 10.1056/NEJMoa1504370. Two Phase 3 Trials of Adalimumab for Hidradenitis Suppurativa. https://www.ncbi.nlm.nih.gov/pubmed/27518661

Bermekimab vs Humira: Pain Patients with 30% reduction and ≥1 unit reduction in pain Score Subjects Achieving % * * Humira Humira + Oral antibiotics N=24 N=18 *Source: N Engl J Med. 2016 Aug 4;375(5):422-34. doi: 10.1056/NEJMoa1504370. Two Phase 3 Trials of Adalimumab for Hidradenitis Suppurativa. https://www.ncbi.nlm.nih.gov/pubmed/27518661 20

Double-Blind, Placebo Controlled, Phase II Study of Bermekimab in Patients with Hidradenitis Suppurativa Refractory to Adalimumab Kanni T, Argyropoulou M, Spyridopoulos T, Pistiki A, Stecher M, Dinarello CA, Simard J, Giamarellos-Bourboulis EJ. J Invest Dermatol. 2018 Apr;138(4):795-801

Primary study endpoint *Fisher’s exact test **Mantel-Haenszel’s statistics CIs: confidence intervals OR: odds ratio ORHiSCR(+) MABp1: 13.50** (95%CIs: 1.19-152.51, p: 0.035)

HiSCR to 24 Weeks 2° endpoint *Fisher’s exact test

Abscesses & Inflammatory Nodule Total Counts 2° endpoint * Comparison of AUCs by the Students “t-test”

ATOPIC DERMATITIS Bermekimab An Anti-IL-1α Monoclonal Antibody Shows Efficacy for Treating Atopic Dermatitis (AD) with Breakthrough Reduction in Itch Data Presented at the American Academy of Dermatology, March 2019

Treatment Regimens Week 0 Week 4 200mg Every Week Baseline Data 1st Injection Endpoint Data After 4 rounds n=10 Week 0 Week 4 Week 8 400mg Every Week Baseline Data 1st Injection Midpoint Data After 4 rounds Endpoint Data After 8 rounds n=28

Subjects Achieving EASI-75 Mean % reduction % Change from Baseline % Subjects Achieving P<0.001 200mg (N=10) 400mg (N=28) 27 Any missing patient data imputed using LOCF

Bermekimab vs Dupilumab EASI-75 Week 8 Week 16 Patients achieving EASI 75 % * Bermekimab Dupilumab (400mg Group, N = 28) * N Engl J Med. 2016 Dec 15;375(24):2335-2348. Epub 2016 Sep 30. Two Phase 3 Trials of Dupilumab versus Placebo in Atopic Dermatitis. https://www.ncbi.nlm.nih.gov/pubmed/27690741

SCORAD Bermekimab vs Dupilumab Week 8 Week 16 Improvement %

Bermekimab vs Dupilumab HADS Combined Score Improvement Week 7 Week 16 Point Reduction SOLO1 SOLO2 Bermekimab Dupilumab (400mg Group, N = 28)

Patients achieving ≥ 4 improvement Patients achieving ≥ 4 points improvement in worst itch NRS score @ week 4 Patients achieving ≥ 4 improvement % (400mg Group, N = 28) Dupilumab

Subjects Achieving ≥4 NRS Score NRS Pain Mean % Reduction Subjects Achieving ≥4 NRS Score Reduction in Pain Mean Reduction % % Subjects Achieving (400mg Group, N = 28) (400mg group, Subjects having ≥ 4 at baseline N = 20) Any missing patient data imputed using LOCF

A shining star on the dermatology horizon: Bermekimab Time Period 8 Weeks* 16 Weeks Therapy Bermekimab 400mg qw   Lebrikizumab 250mg q2w Dupilumab* 300mg q2w Upadacitinib# 30mg daily 15mg daily EASI-75 75%* 61% 44-51% 69% 52% Pruritus NRS % improvement 78%* Not reported 41% 48% Pain NRS ≥4 Decrease 80%* Reported/Studied % http://investor.dermira.com/static-files/7f79814c-812d-4938-8ab3-e0166fc2cc71 * N Engl J Med. 2016 Dec 15;375(24):2335-2348. Epub 2016 Sep 30. Two Phase 3 Trials of Dupilumab versus Placebo in Atopic Dermatitis.https://www.ncbi.nlm.nih.gov/pubmed/27690741 # https://news.abbvie.com/news/abbvies-upadacitinib-abt-494-meets-primary-endpoint-in-phase-2b-study-in-atopic-dermatitis.htm

HS Data Echo the Story for AD % Achieving Positive HISCR %Decrease in Abscess & Lesion Count % Achieving Decrease in Pain Bermekimab Ph2 IV weekly x 12 60 42 -- 400mg SQ weekly x 12 TNF Naive 61 46 67 TNF Failure 63 72 Adalimumab Ph3 40mg SQ weekly x 12 PIONEER I* 29 28 *Source: N Engl J Med. 2016 Aug 4;375(5):422-34. doi: 10.1056/NEJMoa1504370. Two Phase 3 Trials of Adalimumab for Hidradenitis Suppurativa. https://www.ncbi.nlm.nih.gov/pubmed/27518661

Thank you