Pharma BD Deal Intelligence

Merck & Co. Inc. / Seagen Inc.

2020 · Licensing/Option · $4.2B · Complete

Merck's $600M upfront, $1B equity stake, and up to $2.6B in milestones for ladiratuzumab vedotin—paired with TUKYSA ex-U.S. rights for HER2+ cancers—gave Merck breast cancer optionality without full acquisition risk, though the deal's low outcome score suggests the bet underdelivered.

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The coverage arc

Sep 14, 2020 Bullish

Merck and Seattle Genetics ink two new strategic cancer collaborations covering ladiratuzumab vedotin ADC and TUKYSA regional licensing deal.

Apr 17, 2026 Bullish

Seattle Genetics and Merck announce two strategic oncology collaborations including $600M upfront plus $1B equity for ladiratuzumab vedotin co-development.

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Merck and Seattle Genetics (now Seagen) formed two strategic oncology collaborations. Merck paid $600M upfront and made a $1B equity investment for global co-development/co-commercialization of ladiratuzumab vedotin (LIV-1 targeting ADC), with up to $2.6B in milestones. Separately, Merck licensed TUKYSA (tucatinib) for HER2+ cancers in Asia, Middle East, LatAm.

Key facts

Disease & market context

HER2+ Colorectal Cancer

Competitive Landscape

Tukysa (tucatinib, Pfizer/Seagen) received FDA accelerated approval in January 2023 in combination with trastuzumab for RAS-wildtype HER2-positive unresectable/metastatic colorectal cancer (mCRC) after chemotherapy, based on MOUNTAINEER (ORR 38%). HER2 is amplified/overexpressed in ~3-5% of mCRC. Anti-HER2 combinations (direct MOA class, trastuzumab-based): trastuzumab plus pertuzumab (Herceptin + Perjeta, Roche) and trastuzumab plus lapatinib (Tykerb, generic) are NCCN-listed off-label regimens per HERACLES and MyPathway; tucatinib+trastuzumab is the only FDA-labeled HER2-targeted mCRC regimen. Anti-HER2 antibody-drug conjugates: trastuzumab deruxtecan (Enhertu, Daiichi Sankyo/AstraZeneca) received FDA tumor-agnostic accelerated approval April 2024 for HER2+ (IHC 3+) solid tumors including CRC per DESTINY-CRC02 (ORR 38% at 5.4 mg/kg). Bispecifics: zanidatamab (Ziihera, Jazz/BeiGene HER2 biparatopic) is in Phase 2 in HER2+ mCRC. Broader RAS-wildtype 2L+ comparators (cross-MOA share competitors): regorafenib (Stivarga, Bayer), trifluridine/tipiracil (Lonsurf, Taiho) with or without bevacizumab (Avastin, Roche), and fruquintinib (Fruzaqla, Takeda) are FDA-approved refractory options; anti-EGFR cetuximab (Erbitux, Lilly) and panitumumab (Vectibix, Amgen) are ineffective in HER2-amplified tumors per retrospective analyses. Commercial framing: Tukysa+trastuzumab owns the HER2+ mCRC labeled slot; Enhertu is the primary threat with broader ADC profile.

HER2+ Breast Cancer

Competitive Landscape

Tukysa (tucatinib, Pfizer/Seagen) is an oral HER2-selective tyrosine kinase inhibitor FDA-approved April 2020 in combination with trastuzumab and capecitabine for previously treated HER2+ metastatic breast cancer including brain metastases, per HER2CLIMB (PFS HR 0.54, OS HR 0.66). HER2 TKIs (direct MOA class): tucatinib (Tukysa) is differentiated by CNS activity; neratinib (Nerlynx, Puma Biotechnology) is FDA-approved as extended adjuvant and 3L+ with capecitabine but carries severe diarrhea; lapatinib (Tykerb, Novartis, now largely generic) is FDA-approved 2L with capecitabine but displaced. Anti-HER2 antibody-drug conjugates (dominant 2L MOA, highest share): trastuzumab deruxtecan (Enhertu, Daiichi Sankyo/AstraZeneca) is FDA-approved 2L per DESTINY-Breast03 (PFS HR 0.28 vs T-DM1) and HER2-low per DESTINY-Breast04; AstraZeneca reported Enhertu global product sales of $2.57B FY2023 per 20-F; ado-trastuzumab emtansine (Kadcyla, Roche) holds post-neoadjuvant adjuvant label per KATHERINE. HER2 monoclonal antibodies (1L backbone): trastuzumab (Herceptin, Roche plus biosimilars), pertuzumab (Perjeta, Roche), and fixed-dose combination pertuzumab/trastuzumab/hyaluronidase (Phesgo) dominate 1L with docetaxel. Margetuximab (Margenza, MacroGenics) is 3L+. Commercial framing: Enhertu has compressed Tukysa to 3L+ in non-CNS patients; Tukysa's brain-metastasis positioning is its durable niche, supporting ~$500M+ annual franchise value per Pfizer 10-K disclosures.

Triple-Negative Breast Cancer

Competitive Landscape

Ladiratuzumab vedotin (SGN-LIV1A, Merck/Seagen) is a LIV-1-targeting antibody-drug conjugate in Phase 2 for triple-negative breast cancer (TNBC); no LIV-1 ADC is FDA-approved. LIV-1 targeting ADCs (direct MOA class): ladiratuzumab vedotin is the only LIV-1 ADC in late-stage development; no near-peer competitor exists, though early-stage LIV-1 bispecifics and ADCs are reported in Chinese pipelines. Anti-Trop-2 ADCs (dominant 2L+ MOA class in TNBC): sacituzumab govitecan (Trodelvy, Gilead) is FDA-approved 2L metastatic TNBC per ASCENT (OS HR 0.48) with Gilead reporting ~$1.3B FY2023 net sales per 10-K; datopotamab deruxtecan (Dato-DXd, Daiichi Sankyo/AstraZeneca) is in Phase 3 TROPION-Breast02 and under FDA review. Anti-HER2 ADCs (HER2-low subset, ~30-40% of TNBC): trastuzumab deruxtecan (Enhertu, Daiichi/AstraZeneca) per DESTINY-Breast04. Anti-PD-1 plus chemo (1L PD-L1+ and neoadjuvant): pembrolizumab (Keytruda, Merck) plus chemotherapy per KEYNOTE-355 (metastatic CPS >=10) and KEYNOTE-522 (neoadjuvant/adjuvant). PARP inhibitors (gBRCAm): olaparib (Lynparza, AstraZeneca/Merck) and talazoparib (Talzenna, Pfizer). Commercial framing: Trodelvy and Dato-DXd have crowded 2L TNBC; ladiratuzumab vedotin's path-to-approval requires LIV-1 biomarker enrichment and differentiation on efficacy/tolerability versus Trop-2 ADCs, which is a high bar given Trodelvy's established OS benefit.

Deal timeline

Related deals — scored

DealYearValueOutcome
Merck & Co. Inc. / Seagen Inc. (this deal)2020$4.2B29
Merck & Co. Inc. / Acceleron Pharma Inc.2021$11.5B90
Merck & Co. Inc. / Peloton Therapeutics Inc.2019$2.2B88
Merck & Co. Inc. / AstraZeneca PLC2017$8.5B87
Merck & Co. Inc. / Moderna, Inc.2022$250M86
Merck & Co. Inc. / Moderna, Inc.2016$250M84
Merck & Co. Inc. / Eisai Co., Ltd.2018$5.8B83

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