#1Seagen FOURTH QUARTER & FULL YEAR 2022 FINANCIAL & BUSINESS UPDATE February 15, 2023#2Forward-Looking Statements Certain of the statements made in this presentation are forward looking, such as those, among others, relating to the Company's 2023 outlook, including anticipated product sales, revenues, costs and expenses, and its potential for growth; the Company's potential to achieve the noted development and regulatory milestones in 2023 and in future periods, or at all; anticipated activities related to the Company's planned and ongoing clinical trials; the opportunities for, and the therapeutic and commercial potential of, ADCETRIS, PADCEV, TUKYSA, TIVDAK, disitamab vedotin, ladiratuzumab vedotin, the Company's other product candidates, its technologies, and the products and product candidates of its licensees and collaborators; the potential for PADCEV to receive accelerated approval from the FDA based on data from the EV-103 trial; the potential for the Company's products and product candidates to receive regulatory approvals or label expansions; the Company's pipeline; as well as other statements that are not historical fact. Actual results or developments may differ materially from those projected or implied in these forward-looking statements. Factors that may cause such a difference include without limitation: the risks that the Company's ADCETRIS, PADCEV, TUKYSA and TIVDAK net sales, revenues, expenses, costs and financial guidance may not be as expected; risks and uncertainties associated with maintaining or increasing sales of ADCETRIS, PADCEV, TUKYSA and TIVDAK due to competition, unexpected adverse events, regulatory action, pricing and/or reimbursement actions, market adoption by physicians, drug pricing reform, impacts associated with COVID-19 or other factors; the risks that the Company or its collaborators may be delayed or unsuccessful in planned clinical trial initiations, enrollment in and conduct of clinical trials, obtaining data from clinical trials, planned regulatory submissions, and regulatory approvals in the U.S. and in other countries, in each case for a variety of reasons including without limitation the difficulty and uncertainty of pharmaceutical product development, negative or disappointing clinical trial results, unexpected adverse events or regulatory actions and the inherent uncertainty associated with the regulatory approval process; risks relating to collaborations; risks related to the COVID-19 pandemic, the ongoing military conflict between Russian and Ukraine, related sanctions, and related economic, financial and other disruptions. More information about the risks and uncertainties faced by the Company is contained under the caption "Risk Factors" included in the Company's Quarterly Report on Form 10-Q for the quarter ended September 30, 2022, and the Company's subsequent periodic reports filed with the SEC. Seagen disclaims any intention or obligation to update or revise any forward-looking statements, whether as a result of new information, future events or otherwise except as required by applicable law. Seagen 2#34Q and Full Year 2022 Financial Results Conference Call Agenda Introduction Business Review Commercial Performance Financial Performance Research & Development Q&A Seagen Douglas Maffei, Ph.D. - Vice President, Investor Relations David Epstein - Chief Executive Officer Chip Romp - Executive Vice President, Commercial U.S. Todd Simpson - Chief Financial Officer Roger Dansey, M.D. - President, Research and Development 3#4David Epstein Chief Executive Officer#5Record Full Year 2022 Net Product Sales Drives Financial Strength Seagen $ in millions Net Product Sales $477 $628 $1,001 $1,386 $1,707 2018 2019 2020 2021 2022 $2B 2022 total revenue, 25% YoY growth $1.7B 2022 net product sales, 23% YoY growth 5#62022 and Recent Accomplishments Lay the Foundation for Continued Progress Commercial Products Pipeline Assets ✓ EU MAA approval Initiated monotherapy study PADCEV ✓ ✓ EV-103 Cohort K data and regulatory submission Completed EV-302 enrollment DV ✓ Initial EV-103 Cohort H neoadjuvant MIBC data LV Ongoing EU country launches ✓ MOUNTAINEER data in CRC SGN-B6A Initiated combination study with Keytruda Evaluating potential frontline combination approaches with KEYTRUDA ✓ Reported initial Phase 1 data TUKYSA ✓ Completed HER2CLIMB-02 enrollment for 1L/2L mBC1 ✓ Treated first patient in HER2CLIMB-05 1L trial SGN-PDL1V ✓ Initiated phase 1 study SGN-B7H4V ✓ Initiated phase 1 study ADCETRIS ✓ ECHELON-1 longer-term OS data in 1L HL ✓ FDA approval of pediatric indication in 1L HL ✓ innova TV-205 combination data SGN-ALPV ✓ Initiated phase 1 study TIVDAK ✓ Initial innovaTV-207 basket study data SGN-BB228 ✓ Initiated phase 1 study Seagen 1 HER2CLIMB-02 extension study enrollment continues in China 6#7Multi-Product Commercial Portfolio, Label Expansions and Differentiated Pipeline Drive Strong Future Growth Seagen Multi-Product Company Focused on Oncology 4 Approved targeted oncology products with multiple label expansion opportunities ADC Expertise World-leading expertise in validated vedotin platform, exploring new payloads and linkers 18 Clinical programs in progress by YE23 to address areas of high unmet medical need 17 Countries Robust commercialization footprint that can be leveraged and expanded with fully owned novel assets Seagen 7#8Three Strategic Pillars to Drive Impressive Growth - Capitalizing on Seagen's Innovation Power OPTIMIZE full potential of commercial portfolio • 10 potentially registrational studies ongoing with multiple upcoming catalysts Meaningful growth opportunity through potential label expansions • Enhance commercial execution and footprint Seagen • = PRIORITIZE development of most transformative assets 兆 INNOVATE through next-generation ADC technologies Leverage synergies of vedotin ADCs and PD-1s with 9+ combination trials Prioritized portfolio focused on differentiated assets, many with large potential patient populations and global rights Optimize auristatin payload and diversify beyond vedotin with novel linkers and payloads Supplement pipeline with complementary assets through strategic in-licensing 8#9Commercial Portfolio Expansion Opportunities Well Underway - All Four with Positive Growth Potential ČADCET ADCETRIS PADCEV enfortumab vedotin-ejfv Injection for IV infusion 20 mg & 30 mg vials MUC HL brentuximab vedotin for Injection PTCL HL Foundation of care for CD30-expressing lymphomas, CTCL PTCL with survival data and under DLBCL U.S. SOC in second-line + urothelial cancer with goal of encompassing all lines of bladder MIBC NMIBC 2L MUC evaluation in r/r DLBCL CTCL cancer "TUKYSA tucatinib 50 mg 150 mg tablets Best-in-class TKI for HER2+ BC, and first FDA-approved treatment in HER2+ mCRC with ongoing trials in earlier stage disease and other solid tumors Current* Future Potential** Current* Future Potential** HER2+ MBC tivdak tisotumab vedotin-tftv for injection 40 mg Metastatic Cervical HER2+ MCRC 2L HER2+ mBC 2L HER2+ mCRC Adjuvant First-in-class ADC for cervical cancer providing important option in high unmet need setting and further opportunities 2L Metastatic Cervical H&N Current* Future Potential** Bars represent relative size of the addressable market (both current and potential future) within each brand, but not between brands. For all bars, potential addressable Seagen population is not indicative of current or expected market penetration. For illustrative purposes only. Current* Future Potential** *Addressable U.S. patient population based on current indications **Potential addressable U.S. patient population based on ongoing trials. The safety and efficacy of these products have not been established in these future potential indications, and future regulatory approval or commercial availability is not guaranteed. 9#10Within our Clinical Pipeline we Prioritized Those Which Are Most Differentiated and Provide the Greatest Potential Commercial Portfolio & ADCETRIS brentuximab vedotin | for injection PADCEV enfortumab vedotin-ejfv Injection for IV infusion 20 mg & 30 mg vials ADC PLATFORM Late-Stage Pipeline Disitamab Vedotin¹ SGN-B6A Ladiratuzumab Vedotin² SGN-B7H4V tivdak tisotumab vedotin-tfty for injection 40 mg Q TUKYSA tucatinib 50 mg 150 mg tablets OTHER TARGETED MODALITIES SEA-TGT SGN-STNV Early-Stage Pipeline SGN-ALPV SGN-PDL1V SEA-CD705 Novel Payload ADCs³ SGN-BB2286 CEACAM5 ADC3,4 SGN-EGFRd23,7 Seagen 1 Remegen has rights for Asia excluding Japan and Singapore; 2 Co-development and co-commercialization agreement with Merck; 3 Represents programs expected to enter the clinic by YE23; 4 50-50 profit share arrangement with Sanofi; 5 BeiGene has rights outside of the Americas, Europe and Japan for SEA-CD70; 6 Pieris has right to copromote one product; 7 Also known as LAVA-1223 10 10#11Actively Investing to Broadly Leverage Vedotin ADC / Anti-PD1 Clinical Synergy to Drive Patient Response and Durability Vedotin ADCs have shown to combine well with anti-PD1s, amplifying their effect through immunogenic cell death Enhanced clinical benefit seen in multiple combination studies, including ADCETRIS, DV, TIVDAK and PADCEV 9+ combination trials ongoing and others planned PADCEV enfortumab vedotin-ejfv Injection for IV infusion 20 mg & 30 mg vials CADCETRIS brentuximab vedotin for Injection tivdak tisotumab vedotin-tftv for injection 40 mg Ladiratuzumab Vedotin Disitamab Vedotin + Others TBD Seagen® 11#12Strengthening our ADC Pipeline with Novel Targets Leveraging Validated Vedotin Technology Wave 1 Approved Vedotin ADCs Wave 2 Vedotin ADCs in Development & ADCETRIS® brentuximab vedotin | for injection PADCEV enfortumab vedotin-ejfv Injection for IV infusion 20 mg & 30 mg vials tivdak tisotumab vedotin-tftv for injection 40 mg POLIVY¹ polatuzumab vedotin-piiq INJECTION FOR INTRAVENOUS USE 30MG 140MG Disitamab Vedotin Ladiratuzumab Vedotin SGN-B6A SGN-B7H4V SGN-ALPV SGN-PDL1V SGN-STNV Seagen 1 Polivy is developed and commercialized by Roche which utilizes Seagen ADC technology 12#13Building our Discovery Platform for the Short- and Long-Term Through New Technologies and Innovation Wave 3 ~1-3 yrs ADCs employing novel Auristatin and Camptothecin technologies Wave 4 -3-5 yrs ADCs incorporating new cytotoxic and immunostimulatory payloads Wave 5 ~5+ yrs Novel drug conjugate technologies employing diverse mechanisms of action Seagen 13#14Chip Romp Executive Vice President, Commercial U.S.#15Net Product Sales Driven by Strong Demand 4Q22 Net Product Sales grew 26% from 4Q21 YoY Growth 4Q22 480 440 $ in millions $464 NM $432 $428 $18 $17 $16 $383 $86 -9% $369 $11 360 $6 $89 $88 320 $94 $90 $122 +32% 097 $124 $105 240 $93 $100 200 160 120 $238 +35% $202 $219 80 $176 $181 40 4Q21 1Q22 2Q22 3Q22 4Q22 Seagen® Note: Sum of product sales may not equal total net product sales due to rounding; NM = Not meaningful tivdak tisotumab vedotin-tftv for injection 40mg "TUKYSA tucatinib 50 mg 150 mg tablets PADCEV enfortumab vedotin-ejfv Injection for intuin 20mg 30m ADCETRIS brentuximab vedotin for injection 15#16Strong Commercial Execution Across Brands & ADCETRIS brentuximab vedotin I for injection ADCETRIS is the foundation of care for CD30- expressing lymphomas • . Record quarterly sales driven by normalizing diagnosis rates, price, and incremental share gains in 1L CHL Now a NCCN category 1 preferred regimen in 1L CHL • 'TUKYSA tucatinib 50 mg 150 mg tablets TUKYSA regimen remains an important treatment option in 2L+ HER2 metastatic breast cancer • patients, especially with CNS involvement Commercial team has now launched the product into the second line plus setting in HER2+ mCRC >120k patients treated to date across portfolio with brand growth fueled by expanded commercialization engine scaled for future launches Seagen PADCEV enfortumab vedotin-ejfv Injection for IV infusion 20 mg & 30 mg vials PADCEV is a U.S. standard of care in mUC for the post-platinum/CPI treatment setting 4Q22 sales grew +32% YoY Planning for potential label expansion in 1L cisplatin-ineligible mUC patients in mid-2023 tivdak tisotumab vedotin-tftv for injection 40 mg TIVDAK First-in-Class ADC for Metastatic Cervical Cancer • Now a NCCN preferred regimen in 2L+ recurrent or metastatic cervical cancer • Well-positioned in 2L/3L setting; area of high unmet need 16#17Todd Simpson Chief Financial Officer#18Net Product Sales of $1.7 Billion in 2022; 23% Growth Over 2021 In millions 4Q21 3Q22 4Q22 FY21 FY22 Total Revenues Net product YoY Growth $369 $428 $464 $1,386 $1,707 sales In millions 4Q22 FY22 ADCETRIS $176 $219 $238 $706 $839 $528 +23% +25% $510 $498 PADCEV $93 $105 $122 122 $340 $451 $430 $426 TUKYSA $94 $88 $86 $334 $353 TIVDAK $6 $16 $18 $6 $63 $464 +26% +23% Royalty $46 $44 $53 $151 $432 $428 $165 $369 $383 revenues Collaboration & license $15 $38 $11 $38 $91 agreement revenues 4Q21 1Q22 2Q22 3Q22 4Q22 Total $430 $510 $528 $1,574 $1,962 Net Product Sales ■Royalties ■ Collaboration & License Agreement Revenues revenues Seagen Note: Amounts may not total due to rounding 18#19Expenses Reflect Investment in Pipeline and Commercial Expansion In millions 4Q21 3Q22 4Q22 FY21 FY22 Cost of sales $87 $108 $108 $312 $410 Cost of sales increase reflects higher product sales and profit share and includes royalties as well as non-cash amortization R&D expenses $304 $385 $358 $1,229 $1,344 SG&A expenses $211 $210 $216 $716 $821 Total costs & expenses $602 $703 $682 $2,256 $2,575 Other income (loss) 1 ($3) $2 $6 $8 $3 Net income (loss) $175 ($191) ($148) ($674) ($610) • R&D expenses reflect continued investment to expand the potential of our approved products and to advance our pipeline programs SG&A expenses driven by ongoing commercialization efforts and other corporate activities to support our growing business Seagen 1 Includes Investment and other income (loss) and income taxes; Amounts may not total due to rounding 19#202023 Financial Outlook Reflects Portfolio Sales and Total Revenue Growth Net product sales¹ Revenues $1,925 to $2,000 million Royalty revenues Collaboration and license agreement revenues $170 to $185 million $45 to $55 million Total revenues Cost of sales $2,140 to $2,240 million Expenses $420 to $470 million R&D expenses $1,425 to $1,525 million SG&A expenses Non-cash expenses² $880 to $930 million $330 to $375 million • Revenues • Net product sales expected to be $1,925 million to $2,000 million, representing 13-17% growth over 2022 primarily driven by ADCETRIS and PADCEV Royalty revenues reflect increasing sales of ADCETRIS by Takeda in its territories and higher royalties on sales of POLIVY by Roche Collaboration and license agreement revenues include royalties from Astellas for PADCEV sales in its territories, as well as other collaboration activities Expenses • • Cost of sales driven by increased product sales, higher profit share payment to our collaborators, third-party royalties, and non-cash amortization expense R&D expense growth driven by investment to expand commercial products, advance our earlier-stage agents and drive ADC innovation SG&A expenses to support commercial execution to drive growth of our approved products and support our overall growth strategy 1 Net Products Sales include sales of ADCETRIS, PADCEV, TUKYSA and TIVDAK; 2 Primarily attributable to share-based compensation expense distributed Seagen approximately evenly between SG&A and R&D 20 20#21Roger Dansey, M.D. President, Research and Development e#22ADCETRIS Blockbuster Sales Potential Driven by 1L cHL OS Benefit and Recent Pediatric Label Expansion ECHELON-1 OS data¹ resulted in NCCN guidelines update to category 1, preferred regimen² and submitted to FDA Probability of Overall Survival 1.0- 0.9- 0.8- 0.7- 0.6- 0.5- 0.4- 0.3- 0.2- A+AVD ABVD Hazard ratio for death, 0.59 (95% CI, 0.40-0.88) P-0.000 by log-rank test 0.1- 0.0+ T 0 6 12 18 24 30 36 42 48 54 60 66 72 78 Months since Randomization 84 90 96 102 No. at Risk A+AVD ABVD 664 638 626 612 598 584 572 557 538 517 494 461 350 209 97 27 4 0 670 634 614 604 587 567 545 527 505 479 454 411 308 191 84 11 1 0 Phase 2 AN+AD 1L CHL data presented at ASH • Demonstrated 92% CR rate and 95% ORR in Stage I/II 1L patients • 95% Stage III/IV patients progression free at 17 months median follow-up Seagen Collaboration with Takeda ADCETRIS brentuximab vedotin | for injection Currently foundation of care in multiple CD30- expressing lymphomas Pediatric label granted by FDA in high-risk 1L CHL based on positive EFS data presented at ASCO³ and now NCCN category 1 preferred regimen Event free survival (EFS) 0.8 0.6- 0.4- 02- BV-AVE-PC 92.1% (95% CI, 88.4, 94.7) ABVE-PC 82.5% (95% CI 77.4, 86.5) HR 0.41 [CI 0.25, 0.67] p=0.0002 0.0 Years 0 1 2 ABVE-PC 289 BV-AVEPC 298 246 275 226 260 3 164 194 5 112 105 45 45 3 Studies ongoing in DLBCL and solid tumors ⚫ ECHELON-3 DLBCL enrollment ongoing Initial data in solid tumors expected in 1H 2023 1 Ansell, et al, New England Journal of Medicine 2022; 2 NCCN guidelines updated to include ADCETRIS + AVD as a Preferred regimen with Category 1 level of evidence; 3 Castellino, et al, ASCO 2022 Abstract 7504; 4 NCCN guidelines updated to include BV-AVE-PC as a Preferred Regimen with Category 1 level of evidence; refer to ADCETRIS USPI for complete safety information, including a BOXED WARNING for Progressive Multifocal Leukoencephalopathy (PML): JC virus infection resulting in PML and death can occur in ADCETRIS-treated patients 22 22#23Developing PADCEV into a Bladder Cancer Blockbuster and Pursuing Other Solid Tumors Advancing into 1L mUC with Keytruda, Priority Review granted with April 21, 2023 PDUFA¹ EV-103 Cohort K Data Presented at ESMO 2022² 100 80- 60- 40- 97.1% of assessable patients had tumor reduction PD-L1 Score High (CPS ≥10) ■Low (CPS <10) Not evaluable Best Overall Response Confirmed CR/PR Tumor Size (% Change from Baseline) -20 -40 -60- -80- 20 888 -100- EV + P (n=69) 64.5%³ CORR by BICR and rapid responses; median DOR not reached; responses seen regardless of PDL-1 expression Seagen Collaboration with astellas PADCEV enfortumab vedotin-ejfv Injection for IV infusion 20 mg & 30 mg vials Current U.S. SOC in post- platinum / PD-(L)1 metastatic urothelial cancer Enabling potential global registrations with 1L mUC phase 3 trial EV-302 Patient enrollment complete, with topline data estimated by YE232 Evaluating Keytruda combination for MIBC with EV-303 & EV-304 Phase 3 trials • Enrolling in cisplatin-eligible and ineligible patients in curative setting Exploring NMIBC and other solid tumors with trials EV-104 and EV-202, respectively Initial EV-104 and EV-202 data expected 1H 2023 1 In patients ineligible for cisplatin-based chemotherapy; not currently approved for use; 2 Rosenberg, et al, ESMO 2022; 3 Based on study assumptions; additional study details can be found at clinicaltrials.gov; refer to PADCEV USPI for complete safety information, including a BOXED WARNING for Serious Skin Reactions 23#24Robust TUKYSA Development Program Includes Studies in Earlier Stages of Breast and Colorectal Cancer New indication approved by FDA for 2L+ HER2+ mCRC with NCCN guideline update as a primary treatment option1,2 Responses Tucatinib + Trastuzumab Cohorts A + B (n=84) Tucatinib Monotherapy Tucatinib + Trastuzumab Cohort C Post-Crossover (n=30) (n=28) Confirmed 38.1 3.3 ORR, % 17.9 Best overall response per BICR, % CR 3.6 0 0 PR 34.5 3.3 17.9 Enrolling MOUNTAINEER-03 phase 3 potential U.S. confirmatory study in 1L mCRC • Intended to serve as basis for global submissions Seagen Regional collaboration with MERCK TUKYSA tucatinib 50 mg 150 mg tablets TUKYSA combination now NCCN category 1 preferred regimen for the treatment of HER2+ 3L metastatic breast cancers3 TUKYSA combined with Kadcyla could improve efficacy in 2L+ mBC, including patients with brain metastases • HER2CLIMB-02 topline data expected 1H 2023 Exploring combinations with other ADCs . Planned studies in combination with DV • Ongoing signal-seeking study with Enhertu (HER2CLIMB-04) Progressing additional studies in early-stage BC and other HER2-expressing tumors • Basket study data is planned for 1H 2023 1 This indication is approved under accelerated approval; continued approval for this indication may be contingent upon verification and description of clinical benefit in confirmatory trials.; 2 MOUNTAINEER Data Presented at ESMO 2022; 3 TUKYSA+ trastuzumab + capecitabine is now preferred in the 3L setting and remains Category 1 level of evidence per NCCN guidelines; refer to TUKYSA USPI for complete safety information, including WARNINGS AND PRECAUTIONS for diarrhea, hepatotoxicity, and embryo-fetal toxicity 24#25Progressing Development of TIVDAK in Cervical Cancer and Other Solid Tumor Indications innovaTV 205 combination data in 1L+ r/mCC presented at ASCO 20221 demonstrated encouraging anti-tumor activity 2L/3L TV Parameters 1L TV + carbo (N=33)² 1L TV + Keytruda (N=32)³ + Confirmed response rate, 54.5 40.6 38.2 % innovaTV 301 in 2L+ r/mCC intended to serve as basis for global regulatory submissions Enrollment completion expected in 1Q 2023 • Topline data expected by YE23 Keytruda (N=34)4 tivdak tisotumab vedotin-tftv for injection 40 mg Now NCCN preferred regimen for the treatment of 2L+ recurrent or metastatic cervical innovaTV 207 head & neck cancer data planned for 1H 2023 • Data update to include Q2W dose regimen CR, % 12.1 15.6 8.8 PR, % 42.4 25.0 29.4 Median duration of response (DOR), months 8.6 NR5 14.0 cancer6 innovaTV 205 1L+ r/mCC data planned for 2H 2023 Investigating triplet and quad regimens with chemo, Keytruda +/- bevacizumab, replacing taxanes 1 Lorusso, et al, ASCO 2022; combinations not currently approved for use; 2 median follow-up of 14.6;months; 3 median follow-up of 18.8 months; 4 median follow-up of 15.0 months; verification and description of clinical benefit in confirmatory trials; refer to TIVDAK USPI for complete safety information, including a BOXED WARNING for Ocular Toxicity Seagen Collaboration with Genmab "Not reached ; 6 NCCN now lists TIVDAK as a Category 2A preferred regimen; approved under accelerated approval; continued approval for this indication may be contingent upon 25#26Percentage of change from baseline (%) Advancing Disitamab Vedotin (DV) in Urothelial Cancer and other Solid Tumors with Global Rights Excluding Parts of Asia¹ 100 90 80- 70- 1L/2L HER2+ mUC data reinforce vedotin ADC combinability with anti-PD1s² DV + anti-PD1 data presented by RemeGen at ASCO³ HER2 Status: HERO HER 1+ HER 2+ HER 3+ DV + toripalimab demonstrated a 71.8% CORR, which compares to response rates of ~50% seen with DV monotherapy Seagen Disitamab Vedotin Differentiated HER2- targeted antibody conjugated to vedotin drug-linker and MMAE payload Ongoing phase 2 monotherapy study in 2L MUC for potential FDA accelerated approval • Granted FDA Breakthrough Therapy Designation ⚫ Phase 3 Keytruda combination 1L mUC trial to initiate in 2023 Additional studies planned in HER2 low BC . and other HER2-expressing solid tumors HER2 low BC studies to include monotherapy and combinations with TUKYSA or Keytruda ⚫ Gastric cancer and other solid tumor monotherapy and combination trials planned with TUKYSA 1 RemeGen maintains development and commercialization rights for Asia, excluding Japan and Singapore; 2 Not a pivotal trial; 3 Sheng, et al, ASCO 2022 Abstract 4518; not approved for use; most common TRAES were AST increase (65.9%), ALT increase (63.4%) and peripheral sensory neuropathy (63.4%) 26#27We Anticipate Durability Data Mid-2023 for Novel, Wholly-Owned SGN-B6A in Large Tumor Types SGN-B6A Wholly-owned, first-in-class vedotin ADC Targets integrin beta-6, overexpressed in range of solid tumors Antibody engineered for high target selectivity, limiting binding to other integrins • Interim phase 1 monotherapy results show encouraging anti-tumor activity with tolerable safety profile Expansion cohorts ongoing in NSCLC, esophageal, and head and neck cancers Seagen Sum of Diameters (Maximum % Change from Baseline) NSCLC Subset, Dose Escalation¹ Median 3.5 (range: 1 - 8) lines of prior therapy² 100 Treatment Ongoing Q3W 1.8 mg/kg 2Q3W 1.2 mg/kg 2Q4W 80- 1.25 mg/kg 1.5 mg/kg 1.8 mg/kg Q1W 1.0 mg/kg 1.2 mg/kg 2.0 mg/kg 60 40 20 0 -20 -40 NSCLC N=27 -60 -80 CORR, n (%) 95% CI 9 (33.3) (16.5, 54.0) -100 * Individual Patients (N=27) * * * 1 Hollebecque, et al, SITC 2022, Abstract No. 731; not approved for use; most common TEAEs were fatigue (36.7%), nausea (34.2%) and diarrhea (29.1%); 2 Prior therapy includes platinum and anti-PD/L-1 therapy. In patients with driver mutations prior therapy includes TKI and cytotoxic therapy 20% -30% 27 27#28Novel SGN-B7H4V has Potential Utility in Breast, Endometrial and Ovarian Cancer, with Full Global Rights and Initial Data 2H 2023 SGN-B7H4V Novel, vedotin ADC targeting B7-H4, an immune checkpoint that is upregulated in many solid tumors ⚫ B7-H4 expression is low on normal tissue and immune cells, in contrast to certain other members of the B7 family (e.g., B7-H3) Seagen Adapted from Poster No. 854 presented at SITC 2021 B7-H4 is Expression by Tumor Type 1 2 3 Ovarian (high grade serous, n = 63)- Breast (n =151)- Endometrial adenocarcinoma (n = 274) TMA cores 0 20 40 60 80 100 % B7-H4+ (IHC intensity score 1-3, frequency >25% of tumor) 28#292023 is an Important Data and Regulatory Year with Multiple Anticipated Milestones PADCEV enfortumab vedotin-ejfv Invection for IV infusion 20 mg & 30 movials Potential FDA accelerated approval in 1L MUC cis- ineligible patients; PDUFA date April 21, 2023 TUKYSA tucatinib 50 mg 150 mg tablets ❖ ADCETRIS brentuximab vedotin for injection tivdak tisotumab vedotir-litv to injection 40 mg Potential FDA accelerated approval in 2L+ mCRC; PDUFA date Jan 19, 2023 ✓ Pipeline Initial solid tumor data in combination with Keytruda (1H23) Complete patient enrollment for innovaTV 301 in 2L+ r/mCC confirmatory trial (1H23) Additional Ph1 data for SGN-B6A (1H23) Initial Ph1 data for SGN- B7H4V (2H23) Initial EV-104 NMIBC and EV-202 other solid tumor data (1H23) Topline data for HER2CLIMB-02 in 2L+ mBC1 Topline data for EV-302 in 1L mUC estimated by YE231 Initial data from basket study in other HER2- expressing tumors (1H23) Additional product launches ex-US Additional product launches ex-US Potential FDA approval of addition of OS data to HL label; PDUFA date June 29, 2023 (1H23) Additional innovaTV 207 data in H&N cancer (1H23) Topline data for innovaTV 301 in 2L+ cervical cancer expected by YE231 Initial Ph2 data for LV in other solid tumors (2H23) Initiate Ph1 trials for multiple programs² Preclinical data for CEACAM5-targeted ADC partnered with Sanofi (1H23) Seagen 1 Based on study assumptions; additional study details can be found at clinicaltrials.gov; 2 Timing of Ph1 trial initiations will vary based on program; Completed 29 29#30Seagen#31Questions & Answers