1Transformative therapies | Targeting cancer

Julie, treated for metastatic breast cancer on a TUKYSA clinical trial

Transformative Therapies | Targeting Cancer

FIRST QUARTER 2020 FINANCIAL RESULTS

AND BUSINESS UPDATE

April 30, 2020

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Today’s Speakers

Overview and Key Highlights

Research & Development

Clay Siegall, Ph.D., President & CEO

Roger Dansey, M.D., CMO

Todd Simpson, CFOFinancial

Chip Romp, EVP, CommercialCommercial

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Certain of the statements made in this presentation are forward looking, such as those, among others, relating to the Company’s 2020

outlook, including anticipated 2020 revenues, costs and expenses; the Company’s potential to achieve the noted development and

regulatory milestones in 2020 and in future periods; the anticipated reporting of topline data for tisotumab vedotin for the innovaTV 204

trial late in the second or into the third quarter of 2020; anticipated activities related to the Company’s planned and ongoing clinical trials;

the potential for the Company’s clinical trials to support further development, regulatory submissions and potential marketing approvals in

the U.S. and in other countries; the opportunities for, and the therapeutic and commercial potential of ADCETRIS, PADCEV, TUKYSA

and tisotumab vedotin and the Company’s other product candidates and those of its licensees and collaborators; the potential for data

from the EV-103 trial to potentially support registration under accelerated approval regulations in the U.S.; intended expansion of

commercial operations into Europe; as well as other statements that are not historical facts. 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 the risks

that the Company’s ADCETRIS, PADCEV and TUKYSA net sales, revenues, expenses, costs, and other financial guidance may not be

as expected, as well as risks and uncertainties associated with maintaining or increasing sales of ADCETRIS, PADCEV and TUKYSA

due to competition, unexpected adverse events, regulatory action, reimbursement, market adoption by physicians, impacts associated

with COVID-19 or other factors. The Company may also be delayed or unsuccessful in its planned clinical trial initiations, the enrollment in

and conduct of its clinical trials, obtaining data from clinical trials, planned regulatory submissions, and regulatory approvals in each case

for a variety of reasons including the difficulty and uncertainty of pharmaceutical product development, negative or disappointing clinical

trial results, unexpected adverse events or regulatory discussions or actions and the inherent uncertainty associated with the regulatory

approval process. More information about the risks and uncertainties faced by Seattle Genetics is contained under the caption “Risk

Factors” included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019 filed with the Securities and

Exchange Commission (SEC), and the Company’s subsequent periodic and current reports filed with the SEC. Seattle Genetics 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.

Forward-Looking Statements

President and CEO

CLAY SIEGALL, Ph.D.

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Seattle Genetics is a Diversified Global Oncology Company with Three FDA-Approved Products and a Robust Development Pipeline

• Q1 2020 net sales of $34M; strong launch in first full quarter on market

• Pursuing an accelerated approval pathway in first-line metastatic urothelial cancer

• PADCEV + KEYTRUDA to be evaluated in muscle-invasive bladder cancer in

ongoing Merck phase 3 trial

• Q1 2020 net sales $164M; maintaining 2020 guidance range of $675M to $700M

• Partner Takeda continues to make regulatory progress in ROW

• Ongoing and planned trials provide opportunities for additional growth

• Strong FDA label based on HER2CLIMB; U.S. launch underway

• Investing in broad clinical development program

• Expanding European capabilities to support potential ex-U.S. approvals

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Robust Pipeline Employs Novel ADC and IO Technologies

PHASE 1PRECLINICAL

Multiple myelomaSEA-BCMA

Solid tumorsSGN-CD47M

Solid tumorsSGN-CD228A

Pancreatic cancerSEA-CD40

LymphomaSGN-CD30C

MDS, AMLSEA-CD70

Solid tumors, lymphomaSGN-TGT

Triple negative breast cancer, other solid tumorsLadiratuzumab Vedotin

PHASE 2

Solid tumorsSGN-B6A

CancerMultiple INDs Planned

Cervical cancer, other solid tumorsTisotumab Vedotin

Executive Vice President, Commercial

CHIP ROMP

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Record Product Sales in Q1 Driven by ADCETRIS and PADCEV

Net Product Sales ADCETRIS Net Sales Up 22% 1Q20/1Q19

• Growth driven by frontline indications in Hodgkin

lymphoma and PTCL

• A+CHP standard of care in ALCL; focused on

increasing use in other PTCL subtypes

Strong First Quarter of PADCEV Sales

• Robust market uptake following Dec 2019

approval, particularly in the community setting

• Goal to maintain launch momentum in

collaboration with Astellas

TUKYSA Launch Underway

• Interacting virtually with healthcare providers

• Sales reps have average of 18 years oncology

experience, almost all in breast cancer spaceTotal Product Sales $199M in 1Q 2020

$ in millions

$40

$60

$80

$100

$120

$140

$160

$180

$200

$220

1Q19 2Q19 3Q19 4Q19 1Q20

ADCETRIS PADCEV

Chief Financial Officer

TODD SIMPSON

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Financial Results: Revenue Summary

In millions (unaudited) 1Q19 4Q19 1Q20

Net product sales $135.0 $166.4 $198.5

ADCETRIS 135.0 166.2 164.1

PADCEV NA 0.2 34.5

Royalty revenues 15.6 72.3 20.4

Collaboration & license

agreement revenues44.6 51.1 15.6

Total Revenues $195.2 $289.8 $234.5

Note: Amounts may not total due to rounding.

Total Quarterly Revenues

First Full Quarter of PADCEV Sales Reached $34.5M

$ in millions

• Royalty revenues in 4Q19 included $40M milestone

triggered by Takeda achieving sales >$400M

• Collaboration revenues in 1Q19 & 4Q19 included partner

development & regulatory approval milestones as well as

an upfront payment received under a product license

agreement

$0

$50

$100

$150

$200

$250

$300

1Q19 2Q19 3Q19 4Q19 1Q20

Net Product Sales Royalty Collaboration & License Revenue

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Financial Results: Expense Summary

In millions (unaudited) 1Q19 4Q19 1Q20

Cost of sales $10.3 $11.9 $29.4

R&D 158.3 201.1 195.2

SG&A 80.3 115.2 122.2

Total costs and

expenses$248.8 $328.2 $346.9

Investment and other

income (loss)1 40.3 64.2 (56.0)

Net income (loss) (13.3) 25.8 (168.4)

Net income (loss) per

share(0.08) 0.14 (0.98)

Cost of sales now includes both ADCETRIS and PADCEV

• Includes gross profit share with Astellas of $16M in

1Q20 based on PADCEV sales

• Beginning in 2Q, COS will also reflect TUKYSA,

including the non-cash amortization of acquired in-

process R&D

R&D expenses driven by continued investment in pipeline

• PADCEV and TUKYSA clinical trials investment

• Expenses to advance earlier clinical-stage portfolio

SG&A expenses reflect commercialization

efforts of multi-product company

• PADCEV and TUKYSA commercial launches

• Infrastructure costs to support growth

1. Primarily attributable to non-cash investment gain/loss associated

with common stock holdings, which are marked-to-market.

Note: Amounts may not total due to rounding.

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2020 Financial Outlook Unchanged from February 6, 2020*

*Financial guidance provided as of October 26, 2017

Revenues

ADCETRIS U.S. and Canada

net product sales$675 to $700 million

Royalty revenues $105 to $115 million

Collaboration revenues $30 to $50 million

Expenses

R&D expenses $860 to $950 million

SG&A expenses $475 to $525 million

ADCETRIS cost of sales 5% to 6%

Non-cash costs1 $180 to $200 million

1. Primarily attributable to share-based compensation distributed

approximately evenly between SG&A and R&D.

Revenues

• Product sales driven by three brands:

ADCETRIS, PADCEV and TUKYSA

• Given recent launches, no sales guidance on

PADCEV or TUKYSA provided at this time

• Royalty revenues primarily based on Takeda’s

sales of ADCETRIS in ROW

• Collaboration revenues include event-driven

amounts based on collaborator progress

R&D expenses

• Expected to increase in 2020 as PADCEV and

TUKYSA trials ramp up

SG&A expenses

• Driven by PADCEV and TUKYSA launches

• European expansion activities

*Seattle Genetics continues to monitor the impact of the COVID-19 global

pandemic on its business, including product commercialization, clinical trials

and supply chain. To date, the Company has experienced continuity in its

operations. However, the situation is dynamic and there may be an impact on

the Company over time.

Chief Medical Officer

ROGER DANSEY, M.D.

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Broad PADCEV Clinical Development Program

FDA-

approved

indication

PADCEV

monotherapy

in mUC following

platinum and

PD(L)-1

✓Expand

globally

EV-301: phase 3

randomized,

confirmatory trial

Enrollment complete

for mUC patients

following platinum

and PD(L)-1

Primary endpoint OS

Extend

advanced

mUC label

In collaboration with

EV-201: phase 2,

cohort 2

monotherapy

Enrollment complete

for mUC cisplatin

ineligible patients

following PD(L)-1

Primary endpoint

ORR

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Encouraging Phase 1 Data with PADCEV plus KEYTRUDA® in Cisplatin-Ineligible First-line mUC (EV-103 Trial)

Maximal Target Lesion Reduction by PD-L1 status and

Objective Response Rate per Investigator

Data from PADCEV plus KEYTRUDA

support further exploration of a potential

platinum-free combination for 1L mUC

• 73% ORR (n=45, cisplatin-ineligible pts)

• Rapid responses (88% at first assessment)

• Median DOR not reached

• Median PFS: 12 mos

• Median OS: not reached

• Safety profile appears consistent with individual

components of the combination, including rash,

hyperglycemia, peripheral neuropathy and

immune-mediated eventsData presented at ASCO GU 2020

Rosenburg et.al.; Abstract #441

*Combined positive score high ≥10

93% had

tumor reduction

PD-L1 Expression*

High

Low

Not Evaluable

Best Response

• Confirmed CR/PR

Data Supported Second PADCEV

FDA Breakthrough Therapy Designation

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Broad PADCEV Clinical Development Program

Pursue first-line mUC

through two approaches

EV:302: phase 3

PADCEV plus

KEYTRUDA and/or

chemotherapy

Enrolling 1,095 cis-

eligible or ineligible

patients

Primary endpoints

PFS and OS

Advance into

early-stage

bladder cancer

Muscle-invasive

bladder cancer

PADCEV +

KEYTRUDA

cohort added to

ongoing Merck

registrational

phase 3 trial

FDA-

approved

indication

PADCEV

monotherapy

in mUC following

platinum and

PD(L)-1

✓Expand

globally

EV-301: phase 3

randomized,

confirmatory trial

Enrollment complete

for mUC patients

following platinum

and PD(L)-1

Primary endpoint OS

Extend

advanced

mUC label

EV-103: phase 1b/2

trial, randomized

cohort K

Enrolling 150 cis-

ineligible patients to

PADCEV +/-

KEYTRUDA

Primary endpoint

ORR

Accelerated

approval pathwayGlobal,

confirmatory trial

In collaboration with

EV-201: phase 2,

cohort 2

monotherapy

Enrollment complete

for mUC cisplatin

ineligible patients

following PD(L)-1

Primary endpoint

ORR

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TUKYSA U.S. Approval in Metastatic HER2+ Breast Cancer

FDA approval received ~4 months prior

to PDUFA under RTOR

• TUKYSA in combination with trastuzumab

and capecitabine for patients with advanced

unresectable or metastatic HER2+ BC,

including patients with brain metastases, who

have received one or more prior anti-HER2-

based regimens in the metastatic setting

Multiple other marketing applications in review under Project Orbis and in EU

Evaluating additional opportunities in ongoing and planned trials

• Earlier lines of mBC

• Other HER2+ solid tumors, including

colorectal cancer

*See important safety information on TUKYSA.com

HER2CLIMB

Primary

Endpoint:

Progression-Free

Survival*

HER2CLIMB

Key Secondary

Endpoint:

Overall Survival*

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ADCETRIS Future Opportunities Through Ongoing and Planned Registrational or Practice-Informing Trials

Hodgkin Lymphoma

Frontline

STAGE 3/4: ADCETRIS + OPDIVO + AD

STAGE 1/2: ADCETRIS + OPDIVO + AD

Unfit for chemotherapy: ADCETRIS

Relapsed/Refractory Age 5-30: ADCETRIS + OPDIVO

Retreatment ADCETRIS

CD30-Expressing Non-Hodgkin lymphoma

Frontline PTCL Unfit for chemotherapy: ADCETRIS

Relapsed/Refractory DLBCL ADCETRIS + RITUXAN + REVLIMID

Retreatment PTCL ADCETRIS

Under recently expanded clinical

collaboration with BMS

President and CEO

CLAY SIEGALL, Ph.D.

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Our Bold Vision for the Future of Seattle Genetics

• Continue to establish as standard of care in frontline HL and PTCL

• Initiate additional clinical trialsADCETRIS

PADCEV

• Continue strong launch in U.S. with Astellas

• Advance and expand clinical development program, including trials in first-

line mUC

TUKYSA

• Continue launch in U.S. and work with EMA and other regulatory agencies

on approval application reviews

• Advance and expand clinical development program in HER2+ cancers

Pipeline

• Report topline tisotumab vedotin data in late second quarter or into third

quarter 2020 from pivotal trial in metastatic/recurrent cervical cancer

• Advance novel early-stage programs, including ADCs and IO agents

QUESTION & ANSWER PERIOD