#1Inflammation & Immunology Investor Day December 13, 2021 Pfizer Breakthroughs that change patients' lives Confidential 1#2Forward-Looking Statements This presentation and our discussions during this conference call will include forward-looking statements and forward-looking information that are subject to substantial risks and uncertainties, many of which are beyond our control, that could cause actual results to differ materially from those expressed or implied by such statements and information. We include forward-looking statements about, among other topics, Pfizer's Inflammation & Immunology pipeline, inline products and product candidates, including anticipated regulatory submissions, data read-outs, study starts, approvals, clinical trial results and other developing data that become available, revenue contribution, growth, performance, timing of exclusivity and potential benefits; anticipated operating and financial performance; capital allocation objectives; the proposed acquisition of Arena Pharmaceuticals, Inc. by Pfizer; the benefits of the proposed transaction; future opportunities and strategies; growth potential; and expectations for Arena's product pipeline and product candidates, including expected best-in-class and growth potential. Among other things, statements regarding growth; the development or commercial potential of the product pipeline, inline products, product candidates and additional indications, including expected clinical trial protocols, the timing of the initiation and progress of clinical trials and data read-outs from trials; the timing for the submission of applications for and receipt of regulatory approvals; and expected breakthrough, best or first-in-class or blockbuster status of products are forward-looking and are estimates that are subject to change and clinical trial and regulatory success. These statements and information are subject to risks, uncertainties and other factors that may cause actual results to differ materially from past results, future plans and projected future results. Additional information regarding these and other factors affecting such statements can be found in Pfizer's Annual Report on Form 10-K for the fiscal year ended December 31, 2020 and its subsequent reports on Form 10-Q, including in the sections thereof captioned "Risk Factors" and "Forward-Looking Information and Factors That May Affect Future Results", as well as in our subsequent reports on Form 8-K, all of which are filed with the U.S. Securities and Exchange Commission and available at www.sec.gov and www.pfizer.com, and in our press release dated December 13, 2021 regarding the proposed acquisition of Arena. Potential risks and uncertainties also include the impact of and delays caused by COVID-19, including on sales and operations, and on employees, manufacturing, supply chain, marketing, research and development and clinical trials. The forward-looking statements in this presentation and made during our discussions speak only as of the original date of this presentation and we undertake no obligation to update or revise any of these statements. Cross-trial comparisons are not based on head-to-head studies and no direct comparisons can be made. 2Pfizer#3Today's Speakers Aamir Malik EVP, Chief Business Innovation Officer Pfizer Mike Gladstone I&I Global President Mike Corbo I&I Chief Development Officer Mike Vincent I&I Chief Scientific Officer Confidential 3#4Capital allocation priorities Advance internal pipeline • Maintain discipline in deciding where to put our R&D investments to generate the most return • Find creative options to increase our speed, manage risk, and make the most impact on patient health Seek compelling external science • Pursue compelling later-stage assets that can contribute to our top-line growth • Access medical breakthroughs that are in earlier stage of development Accelerate delivery of our medicines 2Pfizer • Find ways where technology and data can play a role to bring more value to patients Confidential 4#5Capital allocation priorities Advance internal pipeline • Maintain discipline in deciding where to put our R&D investments to generate the most return Find creative options to increase our speed, manage risk, and make the most impact on patient health Seek compelling external science • Pursue compelling later-stage assets that can contribute to our top-line growth • Access medical breakthroughs that are in earlier stage of development Accelerate delivery of our medicines Pfizer • Find ways where technology and data can play a role to bring more value to patients Confidential 5#6The Need is Great. The Future is Bright. Patients' Unmet Medical Needs Drive Pfizer's Commitment and Investment in Immuno-Inflammatory Diseases BC Rheumatology 2 Enbrel etanercept XELJANZ [tofacitinib) Inflectra infliximab Gastroenterology XELJANZ [tofacitinib] Ixifi infliximab Inflectra™ infliximab Ixifi® infliximab Medical Dermatology eucrisa crisaborole ointment 2% Staquis crisaborole ointment 2% CIBINQO (abrocitinib) tablets Heterogeneity of patient population in immuno-inflammatory diseases requires a pipeline with multiple complementary mechanisms to address varying patient needs Pfizer *Pfizer has rights to Enbrel outside the US and Canada Confidential 6#7Announcing Agreement to Acquire Arena Pharmaceuticals: An exciting opportunity to offer patients new potential therapies and diversify our Pfizer portfolio Strategic Value to Pfizer and Potential Near-Term options for IBD Patients Anticipated * Strong portfolio fit and capabilities alignment Differentiated potential best-in- class approach MOA diversification revenue contribution in key years This proposed acquisition* provides near-term strength to Pfizer's gastroenterology pipeline and mid to long-term options in additional immuno-inflammatory therapeutic areas. Proposed acquisition targeted to close in the first half of 2022 and is subject to receipt of regulatory approvals and satisfaction of other customary closing conditions. Confidential 7 Pfizer Business Group Business Subgroup#8Pfizer's Expertise in Commercialization Brings Potential Therapies to Patients Sooner о Deep R&D Expertise Ⓒ Robust footprint in immuno- inflammation science Expertise with G protein coupled receptors Extensive network of GI KOLS ①Existing connections with sites. and investigators Global Supply Chain Excellence Manufacturing operational excellence with access to top talent: 11 Distribution / Logistics Centers in 10 Countries Automated Continuous Balance of Supply & Demand Business insights driven by data & analytics, Role-based solutions, eliminating waste Commercial Infrastructure Existing commercial infrastructure to hit the ground running ①Global sales and marketing capabilities ①Existing reach with Gastroenterology specialists Therapeutic area marketing strength Pfizer's global capabilities can potentially bring Etrasimod to market faster, provide more patients access. Pfizer Inflammation & Immunology 8#9Etrasimod: A Selective S1P1, S1P4, and S1P5 Receptor Modulator Etrasimod is a novel oral, selective sphingosine 1- phosphate (S1P) receptor modulator in development for immuno-inflammatory diseases S1PR modulators induce internalization and degradation of the S1P receptor, selectively reducing migration of T and B lymphocytes out of lymphoid organs into blood Etrasimod's unique specificity for the receptor subtypes S1P1, S1P4, and S1P5 may contribute to its clinical benefit:risk profile Why Etrasimod is Potentially Best-In-Class Agent Differentiated pharmacology Lower first-dose HR effect Etrasimod is a potent agonist of the S1P1R and a partial agonist of S1P4R and S1P5R, differentiated from other S1Ps Modest, transient, and asymptomatic first-dose heart rate effect which does not require dose titration Rapid onset/offset Rapid depletion of circulating lymphocytes and rapid recovery upon treatment cessation of effect No long-acting active metabolites No active metabolites with long t₁/2 nor any significant DDI liabilities Pfizer Inflammation & Immunology 6#10Etrasimod: Phase 2 Efficacy in Ulcerative Colitis (UC) . UC Efficacy Overview Randomized placebo-controlled, dose-ranging, Phase 2 study (OASIS) evaluated the efficacy and safety of etrasimod in moderate-to-severe UC patients over 12 weeks • Cross trial comparison showed improved efficacy vs. ozanimod on registration endpoints of clinical remission and endoscopic improvement • • • Similar performance was observed on secondary endpoints (clinical response, histologic remission) Competitive efficacy seen across other approved and emerging treatments in UC ⚫ Phase 3 (ELEVATE) results expected in Q1 2022 • • Ongoing GLADIATOR-UC study to provide clinical evidence for use in moderate patients (expected read- out in Q2/3 2023) Potential best-in-class efficacy for UC and Crohn's Disease Competitive potential efficacy across approved and emerging treatments 2Pfizer Inflammation & Immunology Etrasimod vs. Ozanimod in UC NEW DATA OASIS Post hoc Analysis - TOUCHSTONE Post hoc Analysis - TRUE NORTH Primary Endpoint 100% ETR OASIS Ph2 80% Clinical Remission (3-comp) Week 12 Patients Achieving 3 Component Remission 60% A=25.6; P=0.0002 40% A = 9.3; P=0.0598 30.6% 20% 15.6% 5.6% 0% Placebo (n=54) Etrasimod 1 Etrasimod 2 mg mg (n=52) (n=50) Patients Achieving 3 Component Remission 100% OZANIMOD TOUCHSTONE Ph2 Clinical Remission (3-comp) Week 8* 80%- 60% A-16.2; P=0.0068 40% A=92; P=0.1121 23.9% 20% 16.9% 7.7% 0% Placebo (n=65) Ozanimod Ozanimod 1 0.5 mg (n=65) mg (n=67) Patients Achieving 3 Component Remission 100% OZANIMOD TRUE NORTH Ph3 Clinical Remission (3-comp) Week 10 80%- 60% A 124; P<0.0001 40% 18.4% 20% 6.0% 0% Placebo (n=216) Ozanimod 1 mg (n=429) FDA Required Primary Endpoint used ELEVATE (etrasimod) and True North (ozanimod) RB=0, SF≤1 with Improvement ≥1, Endo score ≤1 OASIS Secondary Endpoint - TOUCHSTONE Secondary Endpoint - TRUE NORTH Secondary Endpoint Patients Achieving Endoscopic Improvement 100% OASIS Ph2 Endoscopic Improvement Week 12 80% 60% A 24.4; P=0.0030 A-4.1; P=0.3059 40% 22.5% 17.8% 20% 0% Placebo (n-54) 41.8% Etrasimod 1 Etrasimod 2 mg (n=52) mg (n=50) Patients Achieving Endoscopic Improvement 100% 80% 60% TOUCHSTONE Ph2 Endoscopic Improvement Week 8* A 220; P=0.0023 A 15.4; P=0.0348 40% 34.3% 27.7% 20% 12.3% 0% Placebo (n-65) Ozanimod Ozanimod 1 0.5 mg (n=65) mg (n=67) Patients Achieving Endoscopic Improvement NEW DATA 100% TRUE NORTH Ph3 Endoscopic Improvement Week 10 80% A 15.7; P<0.0001 60% 40% 20% 11.6% 27.3% 0% Placebo (n=216) Ozanimod 1 mg (n=429) Definition of Endoscopic Improvement An endoscopic subscore of ≤1 point Cross-trial comparisons, not head-to-head studies: no direct comparisons can be m Oasis study: W.J. Sandborn el al. Gastroenterology 2020;158:550-561 True North study: W.J. Sandborn el al. N Engl J Med 2021;385:1280-91 Touchstone study: W.J. Sandborn el al. N Engl J Med 2016; 374:1754-1762 10#11Etrasimod Provides Pipeline Diversification and Significant Potential Revenue Contribution in Critical 2025-2030 Timeframe ◉ Expands Pfizer's current offering in IBD ■ ■ Best-in-Class efficacy potential in Ulcerative Colitis, and robust risk-benefit profile Potential Lifecycle expansion into Crohn's Disease and EOE expands footprint further in Gastroenterology Complementary MOA to current portfolio; potentially enabling treatment of a broader sub-set of UC patients Enhances portfolio in critical years 2021 2022 2023 2024 2025 2026 2027 2028 2029+ XELJANZ [tofacitinib] LOE CIBINQO (abrocitinib) tablets) Ritlecitinib AA Ritlecitinib Vitiligo TL1A and Ritlecitinib Emerging GI Pipeline for UC &CD I&I Portfolio XELJANZ [tofacitinib] Etrasimod Pfizer UC AD CD EOE Dates indicate anticipated future approval timing; all dates are subject to change and subject to clinical and regulatory success EOE: Eosinophilic Esophagitis, IBD: Irritable Bowel Disease, MOA: Mechanism of Action, UC: Ulcerative Colitis, AD: Atopic Dermatitis, AA: Alopecia Areata, LOE: Loss of Exclusivity, CD: Crohn's Disease AA 11#12Pfizer Offers Robust Differentiated Pipeline of Immuno-Inflammation Potential Therapies 3C D Rheumatology Rheumatoid Arthritis; Lupus; Dermatomyositis; Psoriatic Arthritis and Ankylosing Spondylitis Gastroenterology Currently Marketed Products Inflectra™ infliximab XELJANZ [tofacitinib] Enbrel etanercept Ixifi infliximab Investigational Assets ADALIMUMAB-AFZB Adalimumab biosimilar a-IFNẞ IRAK4/Ritlecitinib Combo Covalent JAK3/TEC Inflectra™ infliximab TL1A [tofacitinib) RITLECITINIB Ixifi infliximab Covalent JAK3/TEC Inflammatory Bowel Disease (Crohn's Disease & Ulcerative Colitis); Liver Fibrosis XELJANZ Medical Dermatology Atopic Dermatitis; Acne; Psoriasis; Alopecia Areata; Vitiligo; Pfizer Hidradenitis Suppurativa • • eucrisa crisaborole ointment 2% Enbrel etanercept Not all products are approved in all jurisdictions. Pfizer has rights to Enbrel outside the US and Canada CIBINQO (abrocitinib) tablets) 50ma 100ma 200m Etrasimod* S1P RITLECITINIB Covalent JAK3/TEC Etrasimod* S1P PDE4+ * If acquired 12#13Pfizer Pipeline Highlights: TL1A and Anti-IFNẞ TL1A: A monoclonal antibody for IBD with potential for precision medicine SCIENCE A • TL1A amplifies cytokine production and drives intestinal inflammation and fibrosis Blocking TL1A potentially improves UC disease pathology1 Anti-Interferon ẞ: A monoclonal antibody with first-in-class potential for dermatomyositis and more • IFN-ẞ protein levels elevated in patient blood³ and mRNA levels increased in patient skin Type 1 IFN-ẞ signature in blood and skin. correlates with disease activity in skin REASONS TO BELIEVE • Promising endoscopic improvement in UC patients in Phase 2a Precision medicine approach utilizing key biomarkers for patient selection may enhance clinical outcomes 1. Clarke et al., 2018 mAbs; TL1Ai = Tumor Necrosis Factor-Like Cytokine 1A Inhibitor3; UC = Ulcerative Colitis Pfizer • • . Significant reduction in clinical disease activity (CDASI) in skin observed in Phase 2 Reduction in IFN gene scores vs placebo observed in Phase 2 study ORPHAN (US/UK) & PRIME (EU) designations granted IFNb program in collaboration with Mass General Brigham; 2. Clearview Analysis; 3. Liao et al, Ann Rheum Dis 70:831, 2011; 4. Huard et al. Br J Derm 176: 1224, 2017; CDASI = Cutaneous Disease Area and Severity Index 13#14Pfizer's Differentiated Immuno-Inflammatory Pipeline and Portfolio Brings Potential Value to Patients and Shareholders • • . Serving Patients Pfizer is committed to the patients we serve Heterogeneity of I&I conditions mean that patients need options to find relief Diverse offering of medicines best serves those suffering from immuno-inflammatory diseases • • Strong Strategic Fit Pfizer capabilities aligned to Etrasimod potential therapy areas S1P MOA provides diversification to our pipeline with broad applicability in multiple indications of interest Potential early entry into UC aligns with current Pfizer commercial expertise and a potential AD launch enhances medical dermatology presence Pfizer Inflammation & Immunology • • Value to Shareholders Proposed acquisition aligns with our broader capital allocation strategy to establish a portfolio of both late and early-stage to support 2025-2030 topline growth Deal provides value to both Pfizer and Arena shareholders; Pfizer can effectively commercialize Etrasimod with global expertise 14#15Thank You Pfizer Breakthroughs that change patients' lives 15#16Back-up Slides Pfizer Breakthroughs that change patients' lives 16#17Arena Pipeline Overview Pfizer Asset (MoA) / Indication Pre-Clinic Phase 1 Phase 2 Phase 3 Etrasimod (S1P) • Ulcerative Colitis Crohn's Disease Atopic Dermatitis . Alopecia Areata Eosinophilic Esophagitis Other Pipeline and Partnered Assets Ralinepag (IP agonist) / PAH • RIST4721 (CXCR2) / PPP • • Olorinab (CB2) / IBS Pain Temanogrel (5-HT2A) / MO & RP APD418 (B3-AdrR)/Acute HF Beacon Discovery Inflammation & Immunology 1) PAH = Pulmonary arterial hypertension; HF 1 = Discontinued 17 heart failure; PPP = palmoplantar pustulosis; MO = Microvascular obstruction; RP = Raynaud's Phenomenon