Silence Therapeutics reported positive Phase II results for divesiran, an siRNA designed for polycythemia vera (PV), a rare blood cancer with burdensome phlebotomy requirements. In the SANRECO trial (NCT05499013), divesiran met its primary endpoint with an 88% response rate versus 19% in placebo-controlled groups. Company commentary in the report attributes the efficacy to TMPRSS6 silencing, a gene regulators use to control iron balance and red blood cell production. The program’s clinical framing centers on steadier hematocrit control—measured as percent of red blood cells—while reducing how often patients need phlebotomy. The release also highlights durability in trial follow-up, including a reported total of 36 weeks without requiring phlebotomy for patients on divesiran and dosing intervals as infrequent as every three months. The company links hematocrit control to lower risk of thrombotic events, a major driver of morbidity and mortality in PV. Operationally, the results support moving toward later-stage evaluation of an siRNA approach in PV where the standard-of-care remains driven largely by phlebotomy and symptom management. If the signal holds up in larger studies, divesiran could challenge current hematocrit management paradigms with longer dosing intervals and mechanism-based control.