At the heart of the acquisition is Divesiran, an active substance for the treatment of polycaemia vera. In this chronic condition, the bone marrow produces too many red blood cells. This increases the risk of thrombosis and serious cardiovascular complications. To date, many patients have had to undergo regular therapeutic bloodletting to control their red blood cell count. Divesiran utilises so-called siRNA technology. This specifically suppresses the activity of a gene involved in regulating iron metabolism. The aim is to limit the excessive production of red blood cells and reduce the need for regular bloodletting. In a Phase II trial, the active substance achieved a response rate of 88 per cent compared with 19 per cent for the placebo. In future, treatment could be administered via an injection every three months. A Phase III trial, relevant for regulatory approval, is set to determine whether the results seen so far can be confirmed in larger patient groups. With this acquisition, Merck is continuing its expansion in the specialised medicines sector. Back in 2025, the group had already acquired the US company SpringWorks Therapeutics, thereby expanding its portfolio for rare tumour diseases. In addition to Divesiran, Silence Therapeutics brings further development programmes and its own platform for targeted gene regulation. The British company employs around 80 staff in the UK, the US and Germany. The loan-financed transaction is scheduled to be completed in the first quarter of 2027. This is subject to, amongst other things, shareholder approval and the necessary regulatory approvals. For Merck, the acquisition opens up the opportunity to complement its drug development with RNA-based therapeutic approaches and to further expand its business in the field of rare diseases.
News from “Merck KGaA” dated 19 October 2026