Sirius Therapeutics Announces Promising Phase I Clinical Data from Its Factor XI siRNA, a Long-Acting Next-Generation Anticoagulant for Thromboembolic Disorders

December 10, 2024, SAN DIEGO, CA & SHANGHAI - Sirius Therapeutics today announced promising preliminary data from its Phase 1 first-in-human clinical trial of SRSD107, a next generation siRNA therapeutics under clinical development for the prevention and treatment of thromboembolic disorders, such as myocardial infarction, ischemic stroke, and venous thromboembolism. The trial data were presented during a poster session at the 66th American Society of Hematology (ASH) Annual Meeting and Exposition, held in San Diego, CA.

SRSD107 is designed to inhibit Factor XI (FXI), a protein in the coagulation pathway that has shown potential to reduce thrombosis without significantly increasing the risk of bleeding, a major liability of current drugs.

“In this trial, SRSD107 was safe and well tolerated, with pharmacokinetic parameters consistent with a typical siRNA product,” said Dr. Patrick Yue, Sirius’ Chief Medical Officer. “We are encouraged by the marked, prolonged reduction in FXI antigen and activity, and increase in clotting, or thromboplastin time, that are consistent potent anticoagulation over sustained periods and reduced bleeding risk respectively. The trial provides a strong foundation for Phase 2 clinical studies.” 

Dr. Qunsheng Ji, Sirius Chief Executive Officer added that “presentation of these findings at ASH 2024 underscores Sirius Therapeutics' commitment to advancing innovative treatments for thromboembolic disorders.”

The study was a single-site, randomized double-blind, placebo controlled study to evaluate the safety, tolerability, pharmacokinetics (PK) and pharmacodynamics (PD) of subcutaneously administered SRSD107 in 40 healthy subjects. Five cohorts, each consisting of eight subjects evaluated eight doses of SRSD107, each receiving either a single SRSD107 dose or placebo. In the trial, SRSD107 was safe and well-tolerated. Significant changes from baseline in PD biomarkers were observed, with maximal reductions in FXI antigen and activity > 90% and an aPTT (thromboplastin time) increase of > 100% (i.e., an aPTT ratio > 2.0) at the highest doses tested. The pharmacodynamic effects were durable, with FXI antigen and activity levels remaining suppressed for more than 16 weeks after dosing.

The study is titled, “A Phase 1, Single Ascending Dose Study to Evaluate the Safety, Tolerability, Pharmacokinetics, and Pharmacodynamics of Subcutaneously Administered SRSD107 in Healthy Subjects. For more information on the study and our ongoing clinical trials, please visit Sirius Therapeutics' website (www.siriusrna.com) .

About Thromboembolic Disorders

Thrombosis, or blood clot formation, is the common underlying mechanism of most cases of myocardial infarction, ischemic stroke, and venous thromboembolism. According to a study in The Lancet of regional and global mortality rates, thromboembolic disorders are estimated to cause as many as 1 in 4 deaths worldwide.

About SRSD107

SRSD107 is a novel double-stranded small interfering ribonucleic acid (siRNA). Developed by Sirius Therapeutics, SRSD107 specifically targets human coagulation factor XI (FXI) mRNA and inhibits FXI protein expression, thereby blocking the intrinsic coagulation pathway and promoting anticoagulant/anti-thrombotic effects. SRSD107 has been engineered for the potential to enable once or twice-a-year dosing.

About Sirius Therapeutics

Sirius is an innovative, clinical stage biotech company developing next generation siRNA therapy for global markets. We are dedicated to translating siRNA technology into transformative medicine for patients with chronic diseases. Our most advanced products are SRSD107 for the treatment of thromboembolic disorders, and SRSD101 for the treatment of dyslipidemia. Founded in 2021 by a world-class leadership team and investors, Sirius has established an innovative discovery center in the United States and translational medicine center in China. Sirius has raised nearly US$100 million funding to date from OrbiMed, Creacion Ventures, Hankang Capital, Delos Capital, and the leadership team.