Merck KGaA has agreed to buy UK-based Silence Therapeutics for $1.3 billion, gaining control of an investigational RNA medicine for the rare blood disorder polycythemia vera. Under the deal announced Monday, Merck will pay $20 in cash per U.S.-listed share, a 130% premium. Shareholders representing 14% of voting power have already backed the transaction, which is expected to close in the first quarter of 2027.
The drug, called divesiran, is a short-interfering RNA therapy that works by silencing the TMPRSS6 gene to raise levels of the hormone hepcidin, which curbs iron metabolism. In mid-stage testing, divesiran significantly reduced the number of blood draws patients needed compared with placebo, and more patients on the drug saw red blood cell levels drop below the threshold triggering phlebotomy. If approved, it would compete with Takeda and Protagonist's Mimrylo, as well as older options such as Incyte's Jakafi.
Merck KGaA plans to invest in a Phase 3 program, using its deeper pockets to advance a drug that Silence had limited resources to develop. Analysts have suggested divesiran may not need the nearly 300-patient pivotal trial that Mimrylo required, and some believe its efficacy meaningfully exceeds Mimrylo's. The deal follows Merck's purchase of Springworks Therapeutics last year ais part of a broader push into specialty areas with high unmet need.