Carlsbad, California, 14 November 2025 – Ionis Pharmaceuticals, Inc. and Otsuka Pharmaceutical Co., Ltd. announced that the Committee for Medicinal Products for Human Use (CHMP) has issued a positive opinion recommending approval of DAWNZERA™ (donidalorsen) for the routine prevention of recurrent hereditary angioedema (HAE) attacks in adults and adolescents aged 12 years and older. The opinion now moves to the European Commission (EC) for a final decision, expected in Q1 2026. The recommendation is supported by extensive Phase 3 clinical data demonstrating significant and sustained reductions in HAE attack rates, including when DAWNZERA was self-administered via autoinjector.
Science Significance
DAWNZERA (donidalorsen) represents a next-generation RNA-targeted therapy that silences production of plasma prekallikrein (PKK), a key mediator that triggers the inflammatory cascade underlying HAE attacks. By reducing PKK levels, DAWNZERA directly interrupts the biochemical pathway responsible for episodic, often severe swelling in patients with hereditary angioedema. The CHMP’s positive opinion was based on the OASIS-HAE and OASISplus Phase 3 studies, which showed robust and durable reductions in mean monthly HAE attack rates. Patients treated with DAWNZERA demonstrated significant improvements across multiple clinical endpoints, including attack frequency, severity, and consistency of response over time.
Importantly, the therapy-maintained efficacy even when administered via autoinjector, highlighting its suitability for real-world preventive care. As an RNA-targeted inhibitor of PKK, DAWNZERA introduces a mechanism distinct from C1 esterase inhibitors and kallikrein monoclonal antibodies, marking scientific progress toward more precise and durable preventive HAE treatments.
Regulatory Significance
A CHMP positive opinion signals strong regulatory momentum across the EU framework. For a rare and potentially life-threatening condition such as HAE, regulatory endorsement is a critical milestone, reflecting both clinical evidence strength and unmet medical need. DAWNZERA already received U.S. FDA approval in August 2025 for prophylaxis in patients aged 12 and older, providing an important global regulatory foundation. If approved by the European Commission, DAWNZERA would join a limited number of preventive HAE therapies available to European patients and could become a differentiated option with RNA-targeted precision and flexible self-administration. The positive opinion also reflects the CHMP’s recognition of DAWNZERA’s acceptable safety profile, with most adverse events limited to injection site reactions, upper respiratory infections, urinary tract infections, and abdominal discomfort.
Business Significance
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This milestone strengthens Ionis Pharmaceuticals’ expansion into commercial RNA medicines beyond neurology and cardiometabolic diseases, reinforcing its leadership in RNA-based innovation.
For Otsuka, which holds exclusive rights in Europe and Asia Pacific, the CHMP decision positions DAWNZERA as a strategic anchor therapy in its immunology and rare disease portfolio. A positive EC decision would unlock a major market opportunity in Europe, where demand for effective preventive HAE therapies continues to rise. As a self-injectable, RNA-targeted prophylaxis, DAWNZERA may deliver both medical and commercial advantages through improved patient adherence and reduced treatment burden versus alternatives requiring frequent dosing. Ionis CEO Brett P. Monia, Ph.D., emphasized that the CHMP opinion “reflects the robust clinical evidence supporting DAWNZERA and its potential to deliver a meaningful benefit to people living with HAE in the EU,” highlighting the partnership’s commitment to broad patient access.
Patients’ Significance
HAE is a rare genetic disorder marked by unpredictable, severe swelling episodes affecting the limbs, abdomen, face, and airway. Attack severity varies widely, and laryngeal involvement can be life-threatening. With HAE affecting about 1 in 50,000 people worldwide, access to reliable preventive therapies is essential for reducing morbidity and preventing emergency hospitalizations. DAWNZERA offers a promising new option with: Significant and sustained attack reduction, Convenient self-administration via autoinjector, Once-monthly RNA-targeted mechanism designed for durable physiological impact. For adolescents and adults increasingly seeking independence and stability, DAWNZERA could meaningfully reshape quality-of-life outcomes, daily functioning, and long-term disease control.
Policy Significance
The CHMP’s endorsement underscores the importance of innovation in rare disease medicine and highlights Europe’s ongoing commitment to expanding therapeutic access for underserved patient populations. RNA-based therapies, such as donidalorsen, align with broader policy goals encouraging advanced biologic and nucleic acid technologies, especially when supported by strong real-world usability such as autoinjector compatibility. As healthcare systems seek cost-effective prevention strategies, DAWNZERA’s potential to reduce emergency interventions and hospitalization may support favorable reimbursement decisions. The EC’s forthcoming judgment will be a key indicator of Europe’s readiness to incorporate RNA-targeted preventive therapies into standard HAE management.
Transaction Highlights
The regulatory advancement is grounded in a comprehensive clinical program that evaluated DAWNZERA across multiple global Phase 3 studies. In the OASIS-HAE trial, donidalorsen produced significant reductions in mean monthly HAE attack rates, demonstrating consistent effectiveness across diverse patient profiles. The OASISplus extension study reinforced the durability of response, showing sustained prevention with long-term administration. The studies also confirmed that DAWNZERA maintained efficacy and safety when self-delivered via an autoinjector, supporting its real-world practicality. The CHMP’s positive opinion follows the therapy’s U.S. FDA approval in August 2025, marking a coordinated global regulatory trajectory. Otsuka holds exclusive regional rights to commercialize the therapy across Europe and Asia Pacific, ensuring broad distribution capacity upon approval. As the EC decision approaches, DAWNZERA stands positioned to become one of the most impactful RNA-targeted medicines introduced into the HAE market.
Source: Ionis Pharmaceuticals, Inc. Press Release
