Pharma BD Deal Intelligence

Gilead Sciences Inc. / YM BioSciences Inc.

2012 · Acquisition/Merger · $510M · Complete

Gilead paid ~$510M for momelotinib (CYT387) to challenge Incyte's Jakafi in myelofibrosis, but mixed Phase 3 results led it to shelve the drug and sell it back for just $3M. Momelotinib later succeeded as Ojjaara — under Sierra Oncology and GSK, not Gilead.

CALLED IT — OFF BY 15
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The coverage arc

Dec 12, 2012 Gilead Sciences Bullish

Gilead to acquire YM BioSciences for ~$510 million, gaining CYT387, a once-daily selective JAK1/JAK2 inhibitor with positive Phase 1/2 myelofibrosis data,…

Aug 23, 2018 CNBC Bearish

Gilead paid $510M for momelotinib via YM BioSciences and divested it for just $3M upfront after Phase 3 trials underwhelmed, illustrating one of Gilead's…

Jun 15, 2022 BioSpace Neutral

Momelotinib is profiled as one of pharma's biggest dropped-drug comebacks: Gilead paid $510M to acquire YM BioSciences, abandoned the asset, then watched…

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Gilead tender offer at C$2.95/share cash (~$510M) for YM BioSciences. Acquired CYT387 (momelotinib), JAK1/JAK2 inhibitor for myelofibrosis with positive Phase 1/2 data in 166 patients. Phase 3 planned for H2 2013.

Did it work? Outcome assessment

Strategic verdict
Failed to Achieve
Financial impact
Impaired/Written Down
Gilead paid $510M ($2.95/share) for YM BioSciences in 2013, chiefly for JAK1/2 inhibitor momelotinib (CYT387). After Phase III SIMPLIFY trials disappointed (non-inferior to ruxolitinib on spleen response in SIMPLIFY-1 but failing to beat best available care in SIMPLIFY-2), Gilead deprioritized and divested the program to Sierra Oncology in August 2018 for just $3M upfront plus up to $195M in milestones - effectively a write-off of the original outlay.
Pipeline outcome
Assets Stalled
Momelotinib failed to demonstrate the differentiation Gilead sought in its Phase III myelofibrosis program (SIMPLIFY-1/-2, ~2016) and was shelved, then sold to Sierra Oncology in 2018; the drug was later approved (2023) under different ownership, outside Gilead's hands and the assessment window.

Key facts

Disease & market context

Myelofibrosis

$1.7B US myelofibrosis market 2024 (Jakafi-led)

Disease Overview

Myelofibrosis is a rare clonal myeloproliferative neoplasm characterized by bone-marrow fibrosis, splenomegaly, cytopenias, and constitutional symptoms; transfusion-dependent anemia drives disability and worsens prognosis.

Competitive Landscape

When the YM BioSciences acquisition closed in February 2013, Jakafi (ruxolitinib, Incyte) was the only approved JAK inhibitor for myelofibrosis. Pipeline competitors included Sanofi's fedratinib (acquired from TargeGen) and CTI BioPharma's pacritinib. Momelotinib's differentiation rested on improving anemia and reducing transfusion burden — a clinically meaningful gap left by Jakafi. Gilead's Q1 2013 financial results confirmed closing of the ~$510M deal. However Phase 3 SIMPLIFY-1/-2 (2016) missed the symptom-response endpoint and Gilead divested the program to Sierra Oncology in 2018 for $3M upfront plus milestones. Sierra's MOMENTUM trial (2022) reversed course, leading to GSK's $1.9B Sierra acquisition and FDA approval of momelotinib (Ojjaara) in 2023. The original Gilead deal is now widely viewed as a costly bet that paid off only after divestiture.

Myelofibrosis

$1.7B US myelofibrosis market 2024 (Jakafi-led)

Disease Overview

Myelofibrosis is a rare bone-marrow cancer in which fibrosis crowds out normal hematopoiesis, producing splenomegaly, cytopenias (especially anemia requiring transfusions), and constitutional symptoms. Median survival in higher-risk disease is roughly 5 years and treatment options at deal time were limited largely to ruxolitinib (Jakafi) and stem-cell transplant.

Competitive Landscape

At deal time (December 2012), the myelofibrosis market was a Jakafi (ruxolitinib, Incyte/Novartis) monopoly following its November 2011 FDA approval. Jakafi reduced spleen volume and symptoms but worsened anemia. CYT387 (momelotinib) differentiated on anemia, with Phase 1/2 data in 166 patients showing transfusion independence in a meaningful subset, the rationale Gilead cited in its acquisition of YM BioSciences. Other clinical-stage competitors at the time included Sanofi/TargeGen's fedratinib (later Inrebic) and CTI/Baxter's pacritinib. The deal positioned Gilead to build its first MPN franchise and challenge Jakafi on transfusion-dependent patients. Ultimately the SIMPLIFY-1/-2 Phase 3 trials (2016) missed total symptom score endpoints, Gilead deprioritized the program, and divested the asset to Sierra Oncology in 2018 for $3M upfront. Momelotinib (Ojjaara) was later approved by FDA in 2023 under GSK ownership.

Related deals — scored

DealYearValueOutcome
Gilead Sciences Inc. / YM BioSciences Inc. (this deal)2012$510M17
Gilead Sciences Inc. / Pharmasset Inc.2011$11.2B98
Gilead Sciences Inc. / Triangle Pharmaceuticals Inc.2002$464M96
Gilead Sciences Inc. / CymaBay Therapeutics2024$4.4B76
Gilead Sciences Inc. / Nurix Therapeutics Inc.2019$2.3B69
Gilead Sciences Inc. / Immunomedics Inc.2020$21.0B68
Gilead Sciences Inc. / Kite Pharma, Inc.2017$11.9B67

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