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GSK's $1.9B all-cash acquisition of Sierra Oncology delivered exactly the payoff it was built for: momelotinib won FDA approval as Ojjaara with a broader-than-expected label covering myelofibrosis patients with anemia regardless of prior therapy. Ojjaara/Omjjara posted £554m in FY2025 sales, up roughly 60% year over year, carving out share against Jakafi on its anemia benefit.
GSK acquired late-stage biopharmaceutical company Sierra Oncology for $1.9 billion ($55.00 per share, all-cash), announced 13 April 2022 and completed 29 July 2022. The strategic asset was momelotinib, an oral once-daily JAK1/JAK2 and ACVR1 inhibitor for myelofibrosis. The FDA approved momelotinib as Ojjaara on 15 September 2023 with a broader-than-expected label - the first and only therapy indicated for myelofibrosis patients with anaemia, regardless of prior therapy - supported by the Phase 3 MOMENTUM and SIMPLIFY-1 trials. The deal has largely validated: Ojjaara/Omjjara generated £554m in global sales in FY2025, up roughly 60% year over year, competing against Jakafi and differentiated by its anaemia benefit via ACVR1-mediated hepcidin suppression.
18K US cases/yr · $3.5B Global Myelofibrosis Market (2024)
Myelofibrosis is a rare bone marrow cancer causing scarring, anemia, and enlarged spleen. Approximately 60% of patients develop clinically significant anemia requiring transfusions. Ojjaara is the first and only therapy specifically indicated for MF patients with anemia, regardless of prior treatment.
Ojjaara (momelotinib) uniquely inhibits JAK1/JAK2 and ACVR1, addressing both disease symptoms and anemia. MOMENTUM Phase 3 met all endpoints. FDA granted broader label than expected, enabling use regardless of prior MF therapy. Competes with Jakafi and Vonjo but differentiated by anemia benefit.
GSK completed $1.9B acquisition of Sierra Oncology, gaining Vonjo (pacritinib) for myelofibrosis with severe thrombocytopenia.
FDA approved momelotinib as Ojjaara on 15 Sep 2023 for intermediate/high-risk myelofibrosis with anaemia, regardless of prior therapy - a broader-than-expected label and the first MF therapy specifically addressing anaemia. Based on Phase 3 MOMENTUM and SIMPLIFY-1.
The $1.9B Sierra bet is largely paying off. Momelotinib (Ojjaara/Omjjara) won a broad FDA label in 2023 and reached GBP 554m in global sales in FY2025, up ~60% YoY, approaching blockbuster scale. (Correction: prior record erroneously attributed Vonjo/pacritinib - a CTI BioPharma/Sobi drug - to this deal and claimed GSK divested the asset; both were false.)
| Deal | Year | Value | Outcome |
|---|---|---|---|
| GSK plc / Sierra Oncology Inc. (this deal) | 2022 | $1.9B | 70 |
| GSK plc / SmithKline Beecham | 2000 | $12.0B | 79 |
| GSK plc / Pfizer Inc. | 2018 | $0.0M | 77 |
| GSK plc / Novartis AG | 2014 | $16.0B | 76 |
| GSK plc / Hansoh Pharmaceutical Group Co. Ltd. | 2023 | $1.7B | 74 |
| GSK plc / Nuvalent, Inc. | 2026 | $10.6B | 70 |
| GSK plc / Human Genome Sciences | 2012 | $3.6B | 70 |
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More: 2022 deals · GSK plc deals · Oncology deals