Pharma BD Deal Intelligence

Merck & Co. Inc. / Prometheus Biosciences Inc.

2023 · Acquisition/Merger · $10.8B · Complete

CALLED IT — OFF BY 4
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The coverage arc

Apr 17, 2023 MedCity News Bullish

Merck's $11B Prometheus acquisition brings not just an IBD drug but a precision medicine companion diagnostic platform — a unique opportunity to establish…

Oct 06, 2025 Merck Press Release (Phase 2b expansion) Bullish

Merck initiated three Phase 2b trials of tulisokibart (MK-7240) in hidradenitis suppurativa, radiographic axial spondyloarthritis, and rheumatoid arthritis;…

Apr 17, 2026 Merck Press Release Bullish

Merck today announced that it has entered into a definitive agreement to acquire Prometheus Biosciences, Inc. for $200.00 per share in cash for a total equity…

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Merck acquired Prometheus Biosciences for approximately $10.8 billion ($200.00 per share in cash; announced April 16, 2023, completed June 16, 2023), gaining PRA023 — now branded tulisokibart (MK-7240), a humanized anti-TL1A monoclonal antibody — to strengthen its immunology pipeline. The lead Phase 2 ARTEMIS-UC ulcerative colitis study (published in NEJM, September 26, 2024) showed clinical remission of 26% with tulisokibart versus 1% with placebo at week 12. Post-close, Merck advanced the asset into a two-study Phase 3 IBD program — ATLAS-UC in ulcerative colitis and ARES-CD in Crohn's disease (UC preliminary readout expected November 2026) — and on October 6, 2025 expanded development into three additional immune-mediated inflammatory diseases (hidradenitis suppurativa, radiographic axial spondyloarthritis, and rheumatoid arthritis) via new Phase 2b trials.

Key facts

Related deals — scored

DealYearValueOutcome
Merck & Co. Inc. / Prometheus Biosciences Inc. (this deal)2023$10.8B77
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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