Sirius Therapeutics & CRISPR Partner on $895M+ FXI siRNA Therapy Deal

Over $895 Million! Sirius Therapeutics FXI siRNA Overseas Licensing Agreement

Today (May 20, 2025), Sirius Therapeutics announced a strategic partnership with CRISPR Therapeutics, combining their complementary capabilities in research, development, and commercialization to jointly develop and commercialize the next-generation long-acting Factor XI (FXI) targeted small interfering RNA (siRNA) therapy SRSD107 for the treatment of thrombosis and thromboembolic diseases.

According to the terms of the agreement, Sirius Therapeutics will receive $95 million in cash and cash equivalents from CRISPR Therapeutics (NASDAQ: CRSP) as an upfront payment and is eligible to receive over $800 million in upfront and milestone payments.

The two parties will advance SRSD107’s development under a 50:50 cost and profit-sharing model. Per the agreement, CRISPR will be responsible for commercialization of the product in the United States, while Sirius Therapeutics will manage the Greater China market. In addition, CRISPR Therapeutics has the right to nominate up to two siRNA targets and may choose to lead subsequent clinical development and commercialization. Sirius Therapeutics will be eligible for milestone payments linked to project progress, contingent incentive payments, and tiered royalty revenues based on sales.

SRSD107 is a next-generation long-acting siRNA therapy designed to selectively inhibit coagulation factor XI (FXI). The FXI target plays a key role in pathological thrombosis formation but has minimal impact on normal hemostasis. By targeting FXI, SRSD107 aims to reduce thrombotic events while significantly lowering bleeding risk, demonstrating therapeutic advantages distinct from Factor Xa (FXa) inhibitors. Potential indications for SRSD107 are broad and include atrial fibrillation, venous thromboembolism (VTE), cancer-associated thrombosis, end-stage renal disease patients undergoing hemodialysis, and major orthopedic surgery patients whose existing treatments are limited due to bleeding risk.

Currently, SRSD107 has completed two Phase 1 clinical trials showing safety and good tolerability after single dosing. The related results were presented at the 2025 American College of Cardiology (ACC) Annual Meeting and the 2024 American Society of Hematology (ASH) Annual Meeting. A Phase 2 clinical trial of SRSD107 is launching to evaluate its safety and efficacy in preventing venous thromboembolism (VTE) in patients undergoing knee replacement surgery. This study will provide clinical scientific evidence for confirming its anticoagulant clinical benefit and dosage selection for subsequent pivotal trials.

Dr. Qunsheng Ji, Executive Director and CEO of Sirius Therapeutics, stated: “We are very pleased to enter into this collaboration with CRISPR. CRISPR Therapeutics is a globally recognized leader in gene therapy development. There remains a large unmet medical need in thrombotic diseases, and the encouraging Phase 1 clinical data of SRSD107 further validates its potential as the best-in-class targeted coagulation factor XI (FXI) therapy. Sirius Therapeutics is committed to delivering innovative treatment solutions to patients worldwide. This collaboration will leverage our respective strengths to jointly accelerate the global development and clinical translation of next-generation siRNA therapies.”

Dr. Samarth Kulkarni, Chairman and CEO of CRISPR Therapeutics, said: “We are excited to partner with Sirius Therapeutics and, building on the recent encouraging topline data from the CTX310 program targeting ANGPTL3, further expand our cardiovascular disease pipeline. Factor XI is an innovative and highly attractive target, showing tremendous potential in treating thrombotic diseases affecting millions globally. SRSD107 is expected to become best-in-class, offering major clinical breakthroughs with lower dosing frequency and better clinical outcomes. Sirius Therapeutics’ cutting-edge siRNA platform technology highly complements our existing R&D capabilities, enriching our therapeutic technology platform and helping us develop a broader portfolio of transformative gene therapies.”

About Sirius Therapeutics

Sirius Therapeutics is a clinical-stage biotechnology company committed to human health and wellbeing, leading the development of disruptive siRNA therapies for chronic disease prevention and treatment. Current clinical-stage products include SRSD107 for thromboembolic diseases, SRSD216 for lipoprotein(a), and SRSD101 for dyslipidemia. Founded in 2021, the company is incubated by an internationally excellent management team and globally renowned healthcare investment institutions. Sirius Therapeutics adopts an international strategy, pooling talent and resources from China and the US in the oligonucleotide therapy field, with the US as the source innovation discovery center and China as the global translational medicine center. Utilizing its core oligonucleotide drug development platform, the company has developed multiple differentiated product pipelines with first-in-class or best-in-class potential and global competitive advantages. It has raised nearly $150 million in financing to date.

About CRISPR Therapeutics

Founded over a decade ago, CRISPR Therapeutics has evolved from a research-driven company focused on advancing gene editing programs to an industry leader that celebrated the historic approval of the world’s first CRISPR gene therapy. The company has a diversified pipeline covering broad disease areas including hemoglobinopathies, oncology, regenerative medicine, cardiovascular diseases, autoimmune diseases, and rare diseases. In 2018, CRISPR Therapeutics advanced the first CRISPR/Cas9 gene editing therapy into clinical trials for sickle cell disease and transfusion-dependent β-thalassemia. Since late 2023, CASGEVY® (exagamglogene autotemcel [exa-cel]) has been approved in multiple countries to treat eligible patients with sickle cell disease or transfusion-dependent β-thalassemia. The Nobel Prize-winning CRISPR technology has revolutionized biomedical research, representing a clinically validated powerful approach with the potential to create a new class of transformative medicines. To accelerate and expand its efforts, CRISPR Therapeutics has established strategic partnerships with leading companies such as Vertex Pharmaceuticals. Headquartered in Zug, Switzerland, CRISPR Therapeutics AG’s wholly owned subsidiary CRISPR Therapeutics, Inc. is located in the US, with R&D operations in Boston, Massachusetts, and San Francisco, California.