Sirius Therapeutics-B Files for Hong Kong IPO with Differentiated siRNA Pipeline and Strategic CRISPR Collaboration

On September 28, 2025, Sirius Therapeutics' Hong Kong IPO application was accepted, and the prospectus was officially disclosed.Hankang Capital led the Series B financing of Sirius Therapeutics in 2023 and continued to increase its investment in subsequent rounds.

Sirius Therapeutics, founded in 2021, is committed to fully leveraging the clinical and commercial value of siRNA therapies. Sirius Therapeutics has established a rich and highly differentiated product pipeline, with three final-stage products: FXI siRNA, Lp(a) siRNA, and INHBE siRNA, targeting coagulation disorders, cardiometabolic diseases, and obesity, respectively, all of which hold significant market potential. The lead candidate, FXI siRNA, is currently in Phase II clinical trials in Europe and has entered into a licensing and co-development agreement with CRISPR Therapeutics.

Sirius Therapeutics FXI siRNA and CRISPR Therapeutics adopt a 50:50 co-development model, receiving $25 million in cash, $70 million in equity, and $800 million in milestone payments.

Since its establishment, Sirius Therapeutics has undergone three rounds of financing and completed a $47.5 million Series B2 financing in May 2025, with a pre-investment valuation of $205 million.Post-investment valuation of $252.5 million.

The latest equity structure of Sirius Therapeutics is as follows:

Sirius Therapeutics' FXI siRNA administration can achieve sustained suppression of FXI for up to 6 months.

Sirius Therapeutics' Lp(a) siRNA is currently in Phase II clinical trials. Phase I clinical data showed that the 300mg and 600mg dose groups achieved over 95% inhibition 43 days after dosing, with sustained inhibition lasting at least 12 weeks. Follow-up is still ongoing, with the potential for a single injection every six months or even once a year.

Sirius Therapeutics' PEPR technology platform uses proprietary chemical modification technology, which, when applied to AGT, produces a stronger and more durable knockdown effect on the target protein. The parent sequence without this chemical modification is equivalent to Zilebesiran.

Summary

Small nucleic acids have become another important drug modality beyond antibodies and small molecules, expanding from genetic diseases to common conditions such as cardiovascular diseases, and further to super-indications like obesity. Extrahepatic delivery has facilitated the expansion of small nucleic acids into more therapeutic areas. Sirius Therapeutics has established an siRNA technology platform with significant advantages and, based on this, developed a pipeline with differentiated competitive strengths. The lead program has advanced to Phase II clinical trials, and a co-development cooperation agreement has been reached with CRISPR Therapeutics, retaining half of the market rights in developed countries such as Europe and the United States. It is expected to become a new benchmark for going global in the small nucleic acid field.