Thursday, February 6, 2020

FOURTH QUARTER AND FULL YEAR 2019 FINANCIAL RESULTS AND BUSINESS UPDATE

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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

Robin Taylor, Ph.D., CCOCommercial

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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 future periods and to bring a third product to market in the United States and other countries;

anticipated activities related to the company’s planned and ongoing clinical trials, including clinical trial enrollment and data availability

and the expected timing thereof, including with respect to innovaTV 204, EV-301, EV-302, EV-202, HER2CLIMB-02,

MOUNTAINEER and other clinical trials; the potential for the company’s clinical trials to support further development, regulatory

submissions and potential marketing approvals; the opportunities for, and the therapeutic and commercial potential of ADCETRIS,

PADCEV, tucatinib, and tisotumab vedotin and the company’s other product candidates and those of its licensees and collaborators; 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 net sales, revenues,

expense, and other financial guidance may not be as expected, as well as risks and uncertainties associated with maintaining or

increasing sales of ADCETRIS and PADCEV due to competition, unexpected adverse events, regulatory action, reimbursement, market

adoption by physicians or other factors. The company may also be delayed in its planned clinical trial initiations, 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 in the United States and in other countries. More information about the risks and uncertainties faced by Seattle Genetics

is contained under the caption “Risk Factors” included in the company’s periodic reports filed with the Securities and Exchange

Commission, including the company’s Quarterly Report on Form 10-Q for the quarter ended September 30, 2019 and future periodic

reports filed by the company, including the company's Annual Report on Form 10-K for the year ended December 31, 2019. 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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Diversifying Commercial Portfolio and Revenue Drivers, with Investment Across Our Portfolio to Fuel Future Growth

• Global sales exceed $1B in 2019

• Record 2019 revenues in U.S. and Canada of $628M, up 32% from 2018

• Ongoing and planned trials provide opportunities for additional growth

Tucatinib

Pipeline

• Approved in late December 2019, approximately 3 months ahead of PDUFA

• Early launch phase exceeding internal expectations

• Initiated phase 3 trial in first-line metastatic UC, key to global development strategy

• HER2CLIMB results presented at SABCS, published in NEJM and supported BTD

• NDA submitted under RTOR; MAA validated by EMA; other applications submitted under Project Orbis (Australia, Singapore, Canada and Switzerland)

• Expanding European capabilities to support potential launch

• Expect topline tisotumab vedotin data in 1H20

• Four INDs planned in 2020 and another four in 2021

• Progress by ADC collaborators Roche and GSK, triggering milestone payments

Chief Commercial Officer

ROBIN TAYLOR, Ph.D.

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2020 Product Sales to Include PADCEV and Potentially Tucatinib, Building on ADCETRIS Base

ADCETRIS U.S. / Canada Net Sales*ADCETRIS Y/Y Growth Driven by

Frontline Indications

• Continuing to promote clear advantage of A+AVD

in frontline HL with 4-year PFS update

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

increasing use in other PTCL subtypes

PADCEV Launch Underway

• Number of ordering accounts exceeded our

expectations for January, first full month of launch

• Rapid inclusion in NCCN guidelines

Preparing for Potential Tucatinib Approval

• Sales leadership in place

• Hiring experienced U.S. sales forceGlobal ADCETRIS Sales Exceeded $1B in 2019

$ in millions

*2019 revenues also included $0.2 million of

PADCEV net sales following approval in late

December 2019

$-

$50

$100

$150

$200

$250

$300

$350

$400

$450

$500

$550

$600

$650

2015 2016 2017 2018 2019

FY19 +32% over FY18

Chief Financial Officer

TODD SIMPSON

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Financial Results: Revenue Summary

In millions

(unaudited) 4Q18 3Q19 4Q19 FY18 FY19

Net product

sales1 $132.1 $167.6 $166.4 $476.9 $628.0

Royalty

revenues24.6 27.3 72.3 83.4 138.5

Collaboration

& license

agreement

revenues

17.8 18.4 51.1 94.4 150.2

Total

Revenues$174.5 $213.3 $289.8 $654.7 $916.7

1. Fourth quarter 2019 included $0.2 million of PADCEV net sales following

approval in late December 2019.

Note: Amounts may not total due to rounding.

$0

$50

$100

$150

$200

$250

$300

4Q18 1Q19 2Q19 3Q19 4Q19

Net Product Sales Royalty Collaboration & License Revenue

Total Quarterly Revenues

Record Total Revenues of $917M in 2019

$ in millions

• Royalty revenues included one-time $40M milestone

triggered by Takeda achieving sales >$400M; royalty

rate reached mid-twenty percent

• Collaboration revenues included $75M in payments

under Takeda, Roche, GSK and BeiGene deals

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Financial Results: Expense Summary

In millions

(unaudited) 4Q18 3Q19 4Q19 FY18 FY19

Cost of sales $30.2 $8.7 $9.6 $66.1 $34.9

Cost of royalty

revenues5.4 2.1 2.3 22.2 9.1

R&D 149.8 196.1 201.1 565.3 719.4

SG&A 79.5 96.1 115.2 261.1 373.9

Total costs and

expenses$264.8 $303.0 $328.2 914.7 1,137.3

Investment and

other income (loss)1 (53.2) (2.1) 64.2 13.7 61.9

Income tax benefit2 23.7 - - 23.7 -

Net income (loss) (119.8) (91.9) 25.8 (222.7) (158.7)

Net income (loss)

per share(0.75) (0.55) 0.14 (1.41) (0.96)

R&D expenses driven by continued investment in pipeline

• PADCEV and tucatinib life cycle

development, including registrational trials

• Investment in earlier clinical-stage

portfolio and planned IND submissions

SG&A expenses reflect commercialization efforts of multi-product company

• ADCETRIS frontline indications

• PADCEV commercial launch activities

• Tucatinib launch preparation

• Infrastructure costs to support growth1. Primarily attributable to non-cash investment gain/loss associated with common stock

holdings, which are marked-to-market.

2. Related to intangible assets acquired as part of acquisition of Cascadian Therapeutics.

Note: Amounts may not total due to rounding.

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2020 Financial Outlook Reflects a Year of Transformational Growth

*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%

Cost of royalty revenues Low single-digit percent

on ex-US sales

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 to come from ADCETRIS,

PADCEV and tucatinib (if approved)

• Royalty revenues based on Takeda’s sales of

ADCETRIS in ROW

• Collaboration revenues event-driven based

on collaborator progress

R&D expenses

• Broad investment in ADCETRIS, PADCEV

and tucatinib

SG&A expenses

• PADCEV US launch

• Tucatinib launch preparation

• European expansion activities

Chief Medical Officer

ROGER DANSEY, M.D.

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Broad PADCEV Clinical Development Program

Approved

indication

PADCEV monotherapy

in mUC following

platinum and PD(L)-1

Expand

globally

EV-301: phase 3

randomized,

confirmatory trial

Enrollment completed for

608 mUC patients

following platinum and

PD(L)-1

Primary endpoint OS

Pursue

first-line mUC

Combination with

KEYTRUDA and/or

other agents (cisplatin

or carboplatin)

Initiating 1,095-patient

EV-302 phase 3

randomized trial

Extend across

bladder cancer

Early-stage disease

PADCEV +/-

KEYTRUDA

in muscle-invasive

bladder cancer

Developing strategy in

non-muscle invasive

bladder cancer

✓

Exploring PADCEV in other Nectin-4 expressing solid tumors in EV-202 clinical trial

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Phase 3 Trial Initiated in First-line mUC (EV-302)

• Collaboration between Seattle Genetics, Astellas and Merck

• Three companies jointly funding a global, registrational phase 3 clinical trial to be led by Seattle Genetics

• Enrolling first-line mUC patients regardless of platinum eligibility, PD(L)-1 expression or Nectin-4 expression

• First patient expected to be treated in the first half of 2020

Patient Population

• Previously untreated mUC

• N=1,095

PADCEV + KEYTRUDA®

PLATINUM + GEMCITABINE

PADCEV + KEYTRUDA + PLATINUM

R

1:1:1

Dual Primary Endpoints: PFS and OS

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Broad PADCEV Clinical Development Program

Approved

indication

PADCEV monotherapy

in mUC following

platinum and PD(L)-1

Expand

globally

EV-301: phase 3

randomized,

confirmatory trial

Enrollment completed for

608 mUC patients

following platinum and

PD(L)-1

Primary endpoint OS

Pursue

first-line mUC

Combination with

KEYTRUDA and/or

other agents (cisplatin

or carboplatin)

Initiating 1,095-patient

EV-302 phase 3

randomized trial

Extend across

bladder cancer

Early-stage disease

PADCEV +/-

KEYTRUDA

in muscle-invasive

bladder cancer

Developing strategy in

non-muscle invasive

bladder cancer

✓

Exploring PADCEV in other Nectin-4 expressing solid tumors in EV-202 clinical trial

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Broad Tucatinib Clinical Development Program in HER2+ Diseases

Other HER2+ solid tumors

Planning further trials in

colorectal, gastric and other

solid tumors

Metastatic colorectal cancer

Encouraging interim data

reported from ongoing

MOUNTAINEER trial of

tucatinib + trastuzumab

MOUNTAINEER expanded to

potentially support accelerated

approval

Move into earlier

lines of BC

Metastatic breast cancer;

prior taxane and trastuzumab

Ongoing 460-patient phase 3

trial of tucatinib + T-DM1 vs

T-DM1 + placebo

Neoadjuvant I-SPY2 trial

ongoing and adjuvant trial

under consideration

Metastatic breast cancer;

prior trastuzumab,

pertuzumab and T-DM1

Positive PFS and OS results in

randomized trial in 612 patients

NDA submitted under RTOR;

MAA validated by EMA, other

submissions under Project Orbis

Initial Opportunity Extend across

HER2+ diseasesExpand to

colorectal cancer

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ECHELON-1: Changing the Treatment Paradigm for Patients with Frontline Stage 3/4 Hodgkin Lymphoma

PFS at 4 years of follow up (ITT)

With longer follow up, ECHELON-1

data continue to demonstrate superior

efficacy of ADCETRIS + AVD over

ABVD in frontline advanced HL

• Data reported at ASH 2019 with median

follow-up of 48.4 months

• PFS rates at 4 years:

A + AVD 81.7% vs. ABVD 75.1%

• HR 0.691, p=0.003

• Peripheral neuropathy continued to improve

over time, with most patients experiencing

complete resolution

• 5-year follow-up data expected in 2020

Data presented at ASH 2019

Bartlett, et.al.; Abstract #4026

N=1,334

Median Follow-up

48.4 monthsA + AVD

ABVD

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Future Opportunities Through Ongoing and Planned Registrationaland/or Practice-Informing Trials

Hodgkin Lymphoma

Frontline

STAGE 3/4: ADCETRIS + OPDIVO + AD

STAGE 1/2: ADCETRIS + PD-1 + AD

Unfit for chemotherapy: ADCETRIS monotherapy

Relapsed/Refractory Age 5-30: ADCETRIS + OPDIVO

Retreatment ADCETRIS monotherapy

CD30-Expressing Non-Hodgkin lymphoma

Frontline Unfit for chemotherapy: ADCETRIS monotherapy

Relapsed/Refractory DLBCL: ADCETRIS + RITUXAN + REVLIMID

Retreatment ADCETRIS monotherapy

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 phase 3 trial in

first-line mUC

Tucatinib

• Work with FDA, EMA and other regulatory agencies on approval applications

• Advance robust development program, including in earlier lines of HER2+

BC and other HER2+ malignancies such as colorectal cancer

Pipeline

• Report topline tisotumab vedotin data in 1H20 from pivotal trial in

metastatic/recurrent cervical cancer

• Advance earlier-stage programs and file INDs for many other programs

QUESTION & ANSWER PERIOD