Merck KGaA is buying Silence Therapeutics for $1.3 billion to gain divesiran, a late-stage siRNA candidate for polycythemia vera, after the Phase II SANRECO trial in 48 phlebotomy-dependent PV patients showed clinical response rates of 93.8% with every-6-week dosing and 81.3% with every-12-week dosing, versus 19% for placebo. The deal gives Merck an entry into hematology and a potential best-in-class challenger in PV as divesiran moves toward Phase III.

Why It Matters To Oncology

• Divesiran expands Merck’s oncology-adjacent rare disease strategy into hematology, specifically a myeloproliferative neoplasm where reducing phlebotomy burden is a meaningful clinical goal.

• The siRNA targets TMPRSS6, increasing endogenous hepcidin rather than mimicking it directly, offering mechanistic differentiation from Takeda and Protagonist’s newly approved PV drug Mimrylo (rusfertide).

• Less frequent subcutaneous dosing every 6 or 12 weeks could be a practical advantage if Phase III confirms efficacy and safety, particularly against a once-weekly competitor.

The Financials

• Merck will pay $20 in cash per ADS, representing a 130% premium to Silence’s Oct. 16 close.

• The transaction is valued at $1.3 billion, with an enterprise value of $1.1 billion.

• Merck said the acquisition will be funded with proceeds from new debt and is expected to close in the first quarter of 2027.

What They're Saying

• Merck CEO Kai Beckmann said the deal will strengthen the company’s ability to serve patients with targeted specialty and rare diseases and reflects its continued pipeline shift toward high-specialization areas.

• Healthcare CEO Danny Bar-Zohar called divesiran a potentially best-in-class PV treatment and said the acquisition provides an entry point into hematology through a biologically validated mechanism.

• Silence chair and interim executive Iain Ross said Merck has the scale and commercial capabilities to accelerate Phase III development and bring the therapy to patients.

What's Next

• Merck is expected to take over Phase III development after Silence recently outlined plans to advance divesiran following the positive SANRECO readout.

• Clinicians will be watching whether the Phase II efficacy translates in a larger registrational study, especially durability of hematocrit control and freedom from phlebotomy.

• Competitive positioning against rusfertide will likely hinge on dosing convenience, long-term safety, and whether mechanistic differences translate into differentiated real-world use.

Reference: Merck KGaA, Darmstadt, Germany to Acquire Silence Therapeutics, Strengthening Rare Disease Pipeline with Innovative siRNA Asset