CRSP & Sirius Begin Dosing in Thromboembolic Disorder Study in EU

CRISPR Therapeutics (CRSP) and Sirius Therapeutics have commenced dosing the first patient in a Phase II study in Europe for SRSD107, a novel siRNA therapy targeting Factor XI for the prevention of venous thromboembolism in patients undergoing total knee arthroplasty. This strategic collaboration diversifies CRSP's pipeline into RNA therapeutics beyond its gene therapy focus, contributing to the company's 57.7% year-to-date stock rally. The development follows strong momentum in sales of CRSP's Casgevy gene therapy, which recorded $30.4 million in product revenues during Q2 2025.

Analysis

CRISPR Therapeutics (CRSP) is executing a significant strategic pivot by advancing its pipeline beyond gene therapies into RNA therapeutics. The initiation of a Phase II study for SRSD107, an siRNA therapy for thromboembolic disorders developed with Sirius Therapeutics, marks a critical milestone in this diversification. This move is supported by a 50/50 cost- and profit-sharing agreement, which mitigates financial risk while retaining substantial commercial rights in the U.S. market. This pipeline expansion is occurring alongside positive commercial momentum from its first approved product, the gene therapy Casgevy, co-developed with Vertex. Casgevy sales are accelerating, with Q2 2025 product revenues reaching $30.4 million, more than doubling the $14.2 million from the previous quarter. The market has responded favorably to this dual-pronged strategy of commercial execution and pipeline diversification, evidenced by CRISPR's 57.7% year-to-date share price rally, which substantially outpaces the broader industry's 3.5% rise.

Key Decisions for Investors

• Investors should view the initiation of the SRSD107 Phase II trial as a key de-risking event that validates the company's strategic expansion into siRNA, potentially justifying a more bullish outlook than the current Zacks Rank #3 (Hold) suggests.
• Monitor the commercial ramp-up of Casgevy in upcoming quarters, as continued sales acceleration is crucial for funding the broader pipeline, including the SRSD107 program and next-generation CAR-T candidates.
• While CRSP's stock has performed strongly, the article highlights better-ranked peers like Akero Therapeutics (AKRO) and Adaptive Biotechnologies (ADPT), suggesting investors could consider these names for alternative or supplementary exposure to the high-growth biotech sector.
• The 50/50 partnership structure for SRSD107 warrants attention; while it shares development costs, it also caps the profit potential, a factor to model into long-term valuation scenarios for CRISPR's RNAi platform.