By David Wallace
Silence Therapeutics reported that divesiran met the primary endpoint of the randomized Phase 2 SANRECO trial. Among 48 phlebotomy-dependent polycythemia vera patients, 88% of those receiving divesiran maintained hematocrit below 45% without phlebotomy during weeks 18 through 36, compared with 19% on placebo. The difference was statistically significant.
What the Phase 2 trial found
SANRECO randomized patients to subcutaneous divesiran at 6 mg/kg every six weeks, every 12 weeks, or placebo during a 36-week double-blind period. Response rates were 93.8% with every-six-week dosing and 81.3% with every-12-week dosing. Across weeks 0 through 36, divesiran-treated participants averaged 0.2 phlebotomies versus 2.1 with placebo. The company also reported improvements in hematocrit control, ferritin, and patient-reported MPN symptoms. Detailed data supporting those secondary findings have not yet been released. The company said divesiran was generally well tolerated. Injection-site reactions were infrequent and resolved on their own. Two grade 1, or mild, anemia events were reported.
How divesiran works
Divesiran is an investigational small interfering RNA, or siRNA, treatment. It lowers production of TMPRSS6 in the liver. That raises hepcidin, a hormone that regulates iron, and reduces the iron available to the bone marrow for making red blood cells. This process is intended to control the excess red-cell production that drives high hematocrit in polycythemia vera. The treatment may offer an infrequent injection schedule. These findings do not establish that divesiran affects the underlying MPN clone.
Why this matters for patients
Maintaining hematocrit below 45% is a central treatment goal in PV. The large difference from placebo makes these Phase 2 findings encouraging, especially the response seen with dosing every 12 weeks. The placebo-controlled portion is complete. Patients are continuing in double-blind and open-label extension periods. Silence plans to present full results at ASH 2026 and anticipates starting a Phase 3 trial of every-12-week dosing in the first half of 2027.
What we still do not know
These are company-reported topline data from only 48 patients. The release did not provide detailed tables for symptoms, ferritin, withdrawals, serious adverse events, durability beyond 36 weeks, or outcomes such as blood clots, disease progression, or survival. Stable standard-of-care therapy was permitted. Therefore, it is not possible to determine from this trial how divesiran would perform as a standalone treatment. Divesiran is not FDA approved. Fast Track and Orphan Drug designations do not mean approval. Larger Phase 3 results will be needed to confirm the benefit and better characterize long-term safety.
Key takeaway
Divesiran produced strong hematocrit control without phlebotomy in this Phase 2 trial. Every-12-week dosing could become a meaningful option if the results hold up in a larger study. For now, the findings are promising but preliminary.
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This article is for educational purposes and is not medical advice. Discuss treatment decisions with your healthcare team.
Editorial note: This article was organized with AI-assisted research, then reviewed, edited, and approved by David Wallace.
References
- SANRECO clinical trial record, NCT05499013. ClinicalTrials.gov.
- Phase 2 SANRECO topline results. Silence Therapeutics. August 10, 2026.
- SANRECO Phase 2 presentation. Silence Therapeutics. August 10, 2026.