Merck KGaA plans to acquire Silence Therapeutics for $1.3 billion, adding divesiran, an investigational siRNA therapy for polycythemia vera.
Written By: Mayuresh Salvi, PharmD
Reviewed By: Pharmacally Editorial Team
Silence Therapeutics has entered into a definitive agreement to be acquired by Merck KGaA, Darmstadt, Germany, in an all-cash transaction announced on October 19, 2026. Valued at approximately $1.3 billion in equity terms, the proposed acquisition will expand Merck KGaA’s small interfering RNA (siRNA) capabilities and add an investigational pipeline led by divesiran, a candidate for polycythemia vera (PV).
Under the agreement, Silence shareholders will receive $20 in cash per American Depositary Share (ADS), with each ADS representing three ordinary shares. The offer represents a 130% premium to the closing ADS price on October 16, 2026. The transaction carries an enterprise value of $1.1 billion and an equity value of approximately $1.3 billion.
The Silence board unanimously approved the agreement, while securityholders representing approximately 14% of voting power entered into voting and support agreements. Completion is expected in the first quarter of 2027, subject to shareholder approval, sanction by the High Court of Justice of England and Wales, regulatory approvals, and other customary closing conditions. The acquisition will proceed through a UK scheme of arrangement.
Divesiran Targets Iron Regulation in Polycythemia Vera
Polycythemia vera is a chronic myeloproliferative neoplasm characterised by excessive red blood cell production. Elevated haematocrit can increase thrombotic and cardiovascular risk, while patients may require repeated therapeutic phlebotomies to control red blood cell levels. Treatment may also include cytoreductive agents such as hydroxyurea, interferon or ruxolitinib, depending on individual clinical needs.
Divesiran is an investigational siRNA developed using Silence Therapeutics’ proprietary mRNAi GOLD platform. It is designed to silence TMPRSS6, a gene that negatively regulates hepcidin, the principal hormone controlling iron metabolism.
By suppressing TMPRSS6, divesiran aims to increase hepcidin levels and restrict iron availability for red blood cell production. This mechanism is intended to improve haematocrit control and reduce the need for therapeutic phlebotomy.
The candidate has received Fast Track and Orphan Drug designations from the US Food and Drug Administration for PV. These designations support its development but do not constitute marketing approval.
Phase 2 SANRECO Results Support Further Development
The clinical rationale for the acquisition is supported by positive topline results from the Phase 2 SANRECO trial, announced by Silence Therapeutics on August 10, 2026.
The 36-week, randomised, double-blind, placebo-controlled portion enrolled 48 patients with PV who required phlebotomy despite standard-of-care treatment. Divesiran was administered subcutaneously at 6 mg/kg every six weeks or every 12 weeks.
The primary endpoint was the proportion of patients maintaining haematocrit below 45% without phlebotomy during weeks 18–36. The company reported a clinical response in 88% of patients receiving divesiran, compared with 19% receiving placebo (p<0.0001). Response rates were 93.8% with six-week dosing and 81.3% with 12-week dosing.
The mean number of phlebotomies per patient during weeks 0–36 was also lower with divesiran than with placebo, at 0.2 versus 2.1 (p<0.0001). The company reported improvements in haematocrit control, iron-related markers and patient-reported symptoms.
Divesiran was reported to be well tolerated, with no new safety findings. Injection-site reactions were infrequent and self-limiting, while two cases of Grade 1 anaemia were reported.
These findings provide clinical evidence supporting further investigation of divesiran. However, they are company-reported topline results, and longer-term follow-up and Phase 3 data will be needed to establish the durability of response and fully characterise the benefit–risk profile.
Strategic Rationale and Development Outlook
The acquisition gives Merck KGaA access to both divesiran and Silence Therapeutics’ broader siRNA platform. Silence is also developing candidates for conditions involving elevated lipoprotein(a), cholesterol, obesity and immune-related diseases.
Silence Therapeutics has indicated that a Phase 3 PV trial evaluating divesiran administered every 12 weeks against placebo is expected to begin in the first half of 2027. The proposed acquisition could provide the resources and development infrastructure to advance this programme, although the timeline remains subject to change.
For Merck KGaA, the deal strengthens its focus on specialised medicines and rare diseases through external innovation. For Silence Therapeutics, it provides an opportunity to advance its pipeline within a larger pharmaceutical organisation.
Clinical Interpretation
The acquisition’s clinical significance rests on the combination of a differentiated RNA-silencing mechanism and positive Phase 2 results in phlebotomy-dependent PV. Divesiran’s potential to control haematocrit with less frequent dosing could address an important treatment burden. Nevertheless, the available findings do not establish that the candidate reduces thrombotic events, prevents disease progression or improves survival. Its therapeutic value will depend on confirmation of efficacy, safety and durability in subsequent trials.
The proposed transaction therefore represents a strategic investment in RNA-targeted drug development, with divesiran providing a clinically supported but still investigational lead asset.
References
Silence Therapeutics Enters into Agreement to be Acquired by Merck KGaA, Darmstadt, Germany, Silence Therapeutics, 19 October 2026
About the Writer
Mayuresh Sunil Salvi (Linkedin) is a PharmD professional and healthcare writer with a strong interest in pharmacovigilance, drug safety, and emerging medical research. He is passionate about exploring new drug discoveries, clinical research, and advances in evidence-based medicine. His interests also include ward rounds, prescription audits, and treatment analysis to support rational pharmacotherapy and improved patient care.