Silence Therapeutics

Silence Therapeutics

Silence Therapeutics was founded in 1994 as a spinout from research into RNA interference, a field then in its earliest infancy. It originally listed on the London Stock Exchange's AIM market in 2005 before moving to the main market and, in 2020, securing a Nasdaq listing. Craig Tooman became CEO in 2021, replacing Mark Rothera, whose tenure had navigated a complex merger with InteRNA Technologies that consolidated the Berlin research site. The wealth origin is not a single-family source; the firm is a publicly traded clinical-stage company whose equity is held by institutional investors, not a family office. The firm's strategy is concentrated: develop short interfering RNA (siRNA) therapies that silence disease-causing genes in the liver. Its platform, mRNAi GOLD, uses GalNAc conjugation for targeted delivery to hepatocytes. The pipeline spans hematology and cardiovascular conditions. The lead asset, zerlasiran, is in Phase 3 for elevated lipoprotein(a) — a genetically-driven risk factor for atherosclerotic cardiovascular disease with no approved therapies. Silence out-licensed regional rights to zerlasiran to AstraZeneca for an upfront payment of $20 million in 2020, and to Hansoh Pharma for Greater China in 2021, each deal carrying milestone payments up to $1.3 billion and $1.3 billion respectively. Other disclosed programs include divesiran for polycythemia vera, a Phase 1/2 asset wholly owned, and an earlier-stage iron-chelation program targeting thalassemia and myelodysplastic syndromes. The geographic footprint is European R&D with an American capital base: the Berlin lab drives discovery science, while the London and New York listings fund it. Total deployment is not measured by AUM but by cash runway and R&D spend. As of its 2024 annual report, the firm held over £100 million in cash and equivalents, with a research and development burn rate of approximately £30 million annually. The team size is not publicly fixed in a single portrait, but operations span the London headquarters and the Berlin laboratory. In January 2025, Silence announced a $10 million equity investment from a leading institutional healthcare investor to extend the runway for divesiran's Phase 2 readout. This was not a fund close but a strategic equity placement — a signal that the firm finances itself through public-market raises and licensing deals rather than drawing from a single family's pool of capital. The genuine structural differentiator is Silence's embedded relationship with the largest pharma licensing machine in RNA therapies — AstraZeneca, which itself bet big on the modality through the Alexion acquisition. A small-cap biotech running a Phase 3 program with a top-10 pharma partner while holding full US rights to a wholly owned Phase 2 asset is a rare posture. This is not a family office; it's a publicly traded drug developer whose governance rests with a board and shareholders, not a family council. The company's survival has always depended on proving its siRNA chemistry can be industrialized against materially larger competitors like Alnylam — a pressure that shapes every budget decision and partnership term sheet.