Sirius Therapeutics Announces First Patient Dosed in Phase 2 Trial of SRSD216 for siRNA Therapy for Hyperlipoproteinemia(a)

SAN DIEGO and SHANGHAI December 31, 2025 - Sirius Therapeutics, a clinical stage biotech company developing innovative small interfering RNA (siRNA) therapies for global markets today announced that the first patient has been dosed in a Phase 2 clinical trial of SRSD216, a novel small interfering RNA (siRNA) therapeutic for hyperlipoproteinemia(a), or elevated levels of lipoprotein(a). This milestone marks a significant step towards addressing a significant unmet medical need for patients with elevated Lp(a).

“Dosing the first patient in our Phase 2 trial for SRSD216 brings us one step closer to providing treatment to a large global population, with no existing approved drugs on the market targeting the reduction of Lp(a),” said Dr. Patrick Yue, M.D., Chief Medical Officer of Sirius Therapeutics. “This study will evaluate patients with elevated lipoprotein(a), a risk factor for ASCVD, building on encouraging preliminary results from our ongoing Phase 1 trial.”

“We continue to advance our commitment to exploring siRNA's potential as a novel approach for treating chronic diseases,” stated Dr. Qunsheng Ji, Sirius’s CEO. “This milestone in SRSD216 marks significant progress in our cardiometabolic disease franchise, our second of three franchises anchoring Sirius’s pipeline.”

The ongoing Phase 2 clinical trial is a randomized, double-blind, placebo-controlled design, which will enroll approximately 60 subjects in China and the United States. Eligible subjects must have Lp(a) levels above 150 nmol/L. Subjects will be administered one of three doses of SRSD216: 100 mg, 300 mg, and 600 mg. The primary endpoint is the safety of SRSD216, while the secondary endpoints include PK parameters of SRSD216, and the change in Lp(a) from baseline.

About ASCVD and hyperlipoproteinemia(a)

Atherosclerotic cardiovascular disease (ASCVD) is the most common cause of death worldwide. Dyslipidemia is regarded as a key contributor to the development of ASCVD. While low-density lipoprotein cholesterol (LDL-c) has been considered the primary lipid indicator and target for intervention for decades, numerous studies have identified lipoprotein(a) [Lp(a)] as an independent risk factor for ASCVD. Moreover, Lp(a) is not modified by age, diet, or exercise and currently available pharmacotherapies for dyslipidemia have only modest effects on Lp(a), highlighting a significant clinical unmet need for agents that directly target Lp(a).

About SRSD216
SRSD216 is a double-stranded small interfering ribonucleic acid (siRNA) that specifically modulates the LPA gene, decreasing hepatic Apo(a) production and reducing circulating Lp(a) levels. In pre-clinical studies, analysis has demonstrated high target specificity and clean safety profile. In a Phase 1 study, 3-month interim readouts indicated dose-dependent activity, up to 95% reduction in Lp(a) levels, with reductions persisting for at least 12 weeks and no meaningful safety findings reported after a single subcutaneous dose. Subjects remain in the follow-up period, with data collection ongoing.

About Sirius Therapeutics

Sirius is a global, clinical-stage biotech company developing innovative siRNA therapies focusing on the treatment of chronic diseases. The Company’s pipeline is centered around three key franchises with mega blockbuster potential: coagulation disorders, cardiometabolic diseases, and obesity. Sirius’ most advanced investigational programs include SRSD107, a FXI inhibitor targeting the anticoagulation market, SRSD216, an inhibitor of Lp(a) synthesis intended to address atherosclerotic cardiovascular disease, and SRSD384, an INHBE inhibitor for managing obesity.

Founded in 2021 by a world-class leadership team and investors, Sirius has established an innovation center in the United States and a translational medicine center in China. Sirius has raised nearly US$150 million in funding to date from OrbiMed, Creacion Ventures, Hankang Capital, Delos Capital, and BioTrack Capital.

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