GlaxoSmithKline (GSK) and Sierra Oncology have entered into an agreement under which GSK will acquire Sierra Oncology, a California-based, late-stage biopharmaceutical company focused on targeted therapies for the treatment of rare forms of cancer, for $55 per share of common stock in cash representing an approximate total equity value of $1.9 billion (£1.5 billion).
Myelofibrosis is a fatal cancer of the bone marrow impacting the normal production of blood cells. Anaemia represents a high unmet medical need in patients with myelofibrosis. At diagnosis, approximately 40% of patients are already anaemic, and it is estimated that nearly all patients will eventually develop anaemia. Patients treated with the most commonly used JAK inhibitor will often require transfusions, and more than 30% will discontinue treatment due to anaemia. Anaemia and transfusion dependence are strongly correlated with poor prognosis and decreased overall survival.
Momelotinib has a differentiated mode of action with inhibitory activity along key signalling pathways. This activity may lead to beneficial treatment effects on anaemia and reduce the need for transfusions while also treating symptoms. In January 2022, Sierra Oncology announced positive topline results from the MOMENTUM phase III trial. The study met all its primary and key secondary endpoints, demonstrating that momelotinib achieved a statistically significant and clinically meaningful benefit on symptoms, splenic response, and anaemia.
Luke Miels, Chief Commercial Officer, GSK, said: “Sierra Oncology complements our commercial and medical expertise in haematology. Momelotinib offers a differentiated treatment option that could address the significant unmet medical needs of myelofibrosis patients with anaemia, the major reason patients discontinue treatment. With this proposed acquisition, we have the opportunity to potentially bring meaningful new benefits to patients and further strengthen our portfolio of specialty medicines.”
Stephen Dilly, MBBS, PhD, President and Chief Executive Officer, Sierra Oncology, said: “Uniting with GSK creates the best opportunity for Sierra Oncology to realise its mission of delivering targeted therapies that treat rare forms of cancer while also delivering compelling and certain value for our stockholders. Now we have a partner with a global infrastructure and oncology expertise that enables us to deliver momelotinib to patients as quickly as possible and on a global scale.”
Momelotinib complements GSK’s Blenrep (belantamab mafodotin), building on GSK’s commercial and medical expertise in haematology. The proposed acquisition aligns with GSK’s strategy of building a strong portfolio of new specialty medicines and vaccines. If the transaction is completed and momelotinib is approved by regulatory authorities, GSK expects momelotinib will contribute to GSK’s growing specialty medicines business, with sales expected to begin in 2023, with significant growth potential and a positive benefit to the group’s adjusted operating margin in the medium term.
Under the terms of the agreement, the acquisition will be effected through a one-step merger in which the shares of Sierra Oncology outstanding will be cancelled and converted into the right to receive $55 per share in cash. Subject to customary conditions, including the approval of the merger by at least a majority of the issued and outstanding shares of Sierra Oncology, and the expiration or earlier termination of the waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976, the transaction is expected to close in the third quarter of 2022 or before.
The per share price represents a premium of approximately 39 per cent to Sierra Oncology’s closing stock price on 12 April 2022 and a premium of approximately 63 per cent to Sierra’s volume-weighted average price (VWAP) over the last 30 trading days. Sierra Oncology’s Board of Directors has unanimously recommended that Sierra’s stockholders vote in favour of the approval of the merger. Additionally, stockholders of Sierra Oncology holding approximately 28 per cent of Sierra’s outstanding shares, have agreed to vote their shares in favour of approval of the merger.