Silence Therapeutics reported positive Phase II results for divesiran, an siRNA therapy targeting TMPRSS6 in polycythemia vera (PV). In the SANRECO trial (NCT05499013), divesiran met its primary endpoint with an 88% response rate versus 19% in placebo-controlled groups, positioning the treatment as a hematocrit-control alternative to frequent phlebotomies. The company said divesiran kept hematocrit under control in nearly 90% of treated patients and reduced the need for phlebotomy, with patients reaching a total of 36 weeks without phlebotomy and dosing intervals reported as infrequent as every three months. PV is characterized by overproduction of red blood cells that increases thrombosis risk. Mechanistically, Silence described the siRNA as a “dimmer switch” at the mRNA level, silencing TMPRSS6 to shift iron balance and red blood cell production. The trial readout strengthens the pipeline case for gene-silencing approaches in hematology where treatment burden is a key factor.