Seagen

Seagen Inc.

Company type	Public
Industry	Biotechnology, Pharmaceuticals
Predecessor	Seattle Genetics, Inc.
Founded	1997
Founder	Henry Perry Fell, Jr., Clay Siegall
Headquarters	Bothell , United States
Area served	Worldwide
Key people	David R. Epstein (CEO and Director)
Products	Adcetris (brentuximab vedotin), enfortumab vedotin, tisotumab vedotin, SGN-LIV1A
Number of employees	900+ (2016)
Website	www.seagen.com

Seagen Inc.—previously known as Seattle Genetics, Inc.—is a U.S.-based biotechnology firm focused on developing monoclonal antibody therapies aimed at cancer treatment. Operating from its headquarters in Bothell, Washington, Seagen is recognized as a leader in antibody-drug conjugate (ADC) technology, which selectively targets malignant cells to reduce side effects while improving anticancer activity.

The company’s premier product, Adcetris (brentuximab vedotin), holds approval for four distinct indications and is distributed across more than 65 nations, including the United States, Canada, Japan, and countries within the European Union. Seagen continues to broaden the clinical scope of brentuximab vedotin through comprehensive trials conducted in partnership with Takeda Pharmaceutical Company. While Seagen retains marketing rights in the U.S. and Canada, Takeda oversees commercialization in other territories.

Seagen’s development pipeline features enfortumab vedotin (jointly developed with Astellas Pharma), tisotumab vedotin (in collaboration with Genmab), SGN-LIV1A targeting the LIV-1 protein, alongside several early-stage immuno-oncology candidates.

In January 2018, Seagen bolstered its oncology portfolio by acquiring Cascadian Therapeutics for $614 million. Later, in September 2020, Merck & Co made a $1 billion investment in Seagen to co-develop ladiratuzumab vedotin.

David R. Epstein assumed the role of CEO and Director in November 2022, guiding the company’s strategic direction. Subsequently, in March 2023, Pfizer announced plans to acquire Seagen, aiming to expand its global footprint and strengthen its position within oncology therapeutics.

Collaboration agreements

Seagen maintains strategic partnerships with Takeda Oncology Company for the development and commercialization of brentuximab vedotin. Additionally, it collaborates with prominent biotechnology and pharmaceutical corporations such as AbbVie, Bayer, Celldex Therapeutics, Inc., Daiichi Sankyo, Genentech, Inc., GlaxoSmithKline, Pfizer, Inc., and PSMA Development Company LLC to advance its ADC platform. Further co-development collaborations include agreements with Agensys, Inc. (a subsidiary of Astellas Pharma) and Oxford BioTherapeutics Ltd., enhancing its global reach and market presence.

MMAE-based

Seagen’s proprietary monomethyl auristatin E (MMAE)-based antibody-drug conjugate technology is exemplified by brentuximab vedotin. This approach links a chimeric anti-CD30 monoclonal antibody to MMAE through a protease-sensitive linker. The construct remains stable within circulation but releases MMAE specifically inside CD30-positive tumor cells. This targeted delivery reduces harm to normal tissues while amplifying antitumor potency—highlighting Seagen’s innovative edge in ADC development.

Early years

Established in 1997 by founders Henry Perry Fell, Jr. and Clay Siegall, Seattle Genetics is headquartered in Bothell, Washington. The company launched its initial public offering (IPO) in March 2001 and was subsequently listed on the Nasdaq Stock Market under the ticker SGEN. Prior to its acquisition by Pfizer, it was included in the Nasdaq-100 index. By December 2016, Seattle Genetics had grown to employ over 900 individuals across the United States, demonstrating substantial expansion and a strong investment foundation.

2009

19 February: commenced a key clinical study for brentuximab vedotin aimed at Hodgkin lymphoma.

18 June: initiated a Phase II clinical trial investigating brentuximab vedotin in anaplastic large cell lymphoma patients.

24 July: launched a re-treatment study involving brentuximab vedotin.

10 August: reached a milestone with MedImmune by starting a Phase I trial for MEDI-547.

8 September: achieved progress in partnership with Bayer through submission of an FDA investigational new drug application.

5 October: halted the Phase IIb trial of dazcetuzumab (SGN-40) for diffuse large B-cell lymphoma.

16 November: began Phase I clinical testing of SGN-75 (vorsetuzumab mafodotin).

11 December: terminated collaboration on SGN-40 with Genentech.

21 December: revealed a new antibody-drug conjugate alliance with GlaxoSmithKline, featuring $12 million upfront and potential milestone payments up to $390 million.

In 2009, preparing for the market launch of ADCETRIS, the company concentrated on developing its commercial infrastructure, assembling sales teams across the US and Canada, and partnering with Takeda Pharmaceutical Company for worldwide marketing. By 2018, it had confidently assumed full global commercialization responsibilities.

2010

2 February: launched a Phase I combination clinical trial of brentuximab vedotin (SGN-35) targeting Hodgkin lymphoma.

3 March: secured a milestone achievement within the collaboration with Genentech.

8 April: initiated Phase III clinical testing of brentuximab vedotin for Hodgkin lymphoma post-transplant patients.

20 April: received $9.5 million from Genentech to extend their antibody-drug conjugate partnership.

20 July: started Phase I clinical trial of ASG-5ME focused on pancreatic cancer treatment.

3 August: expanded the Genentech collaboration, including $12 million upfront plus up to $900 million in potential fees and milestones.

2 September: reached a milestone with Agensys (an affiliate of Astellas) by starting a Phase I trial of AGS-16M8F, an ADC targeting renal and liver cancers.

14 September: entered into an antibody-drug conjugate research partnership with Genmab.

20 October: commenced Phase I clinical trial of ASG-5ME for prostate cancer therapy.

2011

6 January: Seattle Genetics formed a partnership with Pfizer, involving an $8 million upfront payment and potential milestones exceeding $200 million.

1 March: began a Phase I clinical trial combining brentuximab vedotin with chemotherapy for systemic anaplastic large cell lymphoma.

15 March: broadened collaboration with Millennium Pharmaceuticals (now Takeda Oncology).

22 March: announced a new collaboration agreement with Abbott, including an $8 million upfront payment plus royalties and milestone incentives.

11 April: James Fan, clinical programming manager, died by suicide after being indicted on insider trading charges linked to Seattle Genetics securities.

19 April: expanded partnership efforts with Genmab.

19 August: obtained accelerated FDA approval for brentuximab vedotin to treat both Hodgkin lymphoma and systemic anaplastic large cell lymphoma (ALCL).

23 August: launched a Phase II trial evaluating ADCETRIS in patients with CD30-positive non-Hodgkin lymphoma.

9 September: entered into collaboration with Oxford BioTherapeutics focused on antibody-drug conjugates for oncology indications.

25 October: initiated Phase II clinical study of ADCETRIS targeting CD30-positive non-lymphoma cancers.

2012

4 June: Presented interim Phase I results for ASG-5ME in prostate cancer.

5 July: Launched a global Phase III study of ADCETRIS aimed at CD30-positive cutaneous T-cell lymphoma.

24 August: Initiated Phase Ib trial combining SGN-75 (vorsetuzumab mafodotin) with everolimus for renal cell carcinoma treatment.

9 October: Reached a significant milestone with Genentech as two antibody-drug conjugates progressed to Phase II studies.

17 October: Commenced Phase II investigation of ADCETRIS as initial therapy for Hodgkin lymphoma patients aged 60 and above.

23 October: Expanded partnership agreement with Abbott, including $25 million upfront and potential milestones up to $220 million.

1 November: Began global Phase III trial evaluating ADCETRIS in previously untreated advanced Hodgkin lymphoma cases.

26 November: Awarded orphan drug status for ADCETRIS in the treatment of mycosis fungoides.

2013

1 February: Health Canada granted approval for ADCETRIS (brentuximab vedotin) to treat relapsed or refractory Hodgkin lymphoma.

6 February: Initiated two separate Phase I clinical trials for SGN-CD19A.

25 June: Entered a new antibody-drug conjugate collaboration with Bayer.

15 July: Launched Phase I trial for SGN-CD33A targeting acute myeloid leukemia (AML).

15 August: Started Phase II study of ADCETRIS in patients with diffuse large B-cell lymphoma.

21 October: Initiated Phase I trial of SGN-LIV1A targeting LIV-1-positive metastatic breast cancer.

2014

29 September: Brentuximab vedotin met the primary endpoint as consolidation therapy in a late-stage lymphatic cancer clinical trial.

8 December: Presented data on Brentuximab Vedotin in diffuse large B-cell lymphoma at the American Society of Hematology Annual Meeting.

2015

12 January: Announced clinical collaboration with Bristol-Myers Squibb to assess combination therapy of brentuximab vedotin and nivolumab in blood cancers.

18 February: Filed Supplemental Biologics License Application (BLA) for Brentuximab Vedotin targeting post-transplant Hodgkin lymphoma patients at high risk of relapse.

8 June: Formed partnership with Unum Therapeutics to co-develop and commercialize antibody-coupled T-cell receptor (ACTR) therapies, with deal value up to $645 million.

31 December: Recorded Adcetris sales totaling $226 million, demonstrating strong commercial growth.

2016

Ranked last among the Annual Top 25 Biotech Companies by Genetic Engineering & Biotechnology News editorial team.

28 March: Announced plans to develop 12 additional therapeutic candidates and expand workforce by 100 employees to support business expansion.

2020

The company rebranded from Seattle Genetics to Seagen Inc., reflecting a strategic shift in corporate branding and market focus.

2022

In July, Merck & Co. progressed into advanced negotiations to acquire Seagen Inc., with the transaction potentially valued above $40 billion. The company aimed to complete the acquisition by August 2022, following the release of its fiscal second-quarter earnings.

2023

In March 2023, Pfizer reached an agreement to purchase Seagen for around $43 billion. This acquisition encompassed FDA-approved therapies such as Adcetris (used for lymphomas), Padcev (for bladder cancer), Tivdak (targeting cervical cancer), and Tukysa (for breast and colorectal cancers), in addition to Seagen's developmental drug portfolio.

Subsequently, Pfizer decided to cancel its plans for constructing a large-scale manufacturing plant in Everett, Washington, which had been planned to commence operations in 2024.

Product portfolio and pipeline

• ADCETRIS: authorized for treatment of Hodgkin lymphoma and systemic anaplastic large cell lymphoma.
• SGN-75 (vorsetuzumab mafodotin): a humanized IgG1 monoclonal antibody conjugate currently in Phase I clinical trials, aimed at relapsed or refractory renal cell carcinoma and non-Hodgkin lymphoma.
• ASG-5ME: an investigational agent targeting solid tumors expressing SLC44A4, including pancreatic, prostate, and gastric cancers.
• Enfortumab vedotin (ASG-22ME): co-developed equally with Astellas, this drug targets Nectin-4 and is intended for bladder, breast, lung, and pancreatic cancers.
• SGN-CD19A: a therapeutic candidate designed for treating hematologic malignancies.