Health Canada Approves DAWNZERA® (donidalorsen) for the Prevention of Hereditary Angioedema Attacks

Approval marks CELYSTRA Pharma's second product approved by Health Canada in nine months and brings a new treatment option for Canadians living with hereditary angioedema

MONTREAL, Sept. 30, 2026 /CNW/ -- CELYSTRA Pharma today announced that Health Canada has approved DAWNZERA^TM (donidalorsen) for the prevention of attacks of hereditary angioedema (HAE) in adult and pediatric patients 12 years of age and older.

The approval marks CELYSTRA's second Health Canada approval in nine months. The company's first product, TRYNGOLZA^® (olezarsen), was approved for the treatment of familial chylomicronemia syndrome (FCS). CELYSTRA licensed the Canadian rights to DAWNZERA and TRYNGOLZA from Ionis Pharmaceuticals.

HAE is a rare and potentially life-threatening genetic condition estimated to affect approximately 1 in 50,000 people. It is characterized by recurrent attacks of severe swelling (angioedema) in various parts of the body, including the hands, feet, genitals, abdomen, face and throat. Because attacks can occur unpredictably, HAE can have a significant impact on daily life.

"Hereditary angioedema can be a challenging disease to live with. Attacks are often unpredictable, can be extremely painful and, in some cases, life-threatening," said Dr. Stephen Betschel, Staff Clinical Immunologist and Allergist at Unity Health, St. Michael's Hospital, Toronto, and Chair of the Canadian Hereditary Angioedema Network. "Preventing attacks is a key part of managing HAE. The approval of DAWNZERA gives physicians and their patients another important option for preventing attacks and managing HAE over the long term."

A New Option for the Prevention of HAE Attacks

DAWNZERA is an RNA-targeted medicine designed to reduce the production of plasma prekallikrein (PKK), which plays an important role in activating inflammatory mediators associated with acute attacks of HAE.

DAWNZERA 80 mg is self-administered by subcutaneous injection once every four weeks (Q4W) or eight weeks (Q8W) using a single dose pre-filled autoinjector.

Health Canada's approval was supported by the pivotal OASIS-HAE Phase 3 study and its open-label extension, OASISplus-HAE.

OASIS-HAE was a global, multicentre, randomized, double-blind, placebo-controlled Phase 3 study in patients with HAE. The study met its primary endpoint, with DAWNZERA Q4W significantly reducing the monthly HAE attack rate by 81% compared with placebo over 24 weeks. From the second dose, the reduction was 87%, a key secondary endpoint. DAWNZERA Q4W also reduced moderate-to-severe HAE attacks by approximately 90% over 24 weeks when measured from the second dose.

The ongoing OASISplus open-label extension (OLE) study provides additional longer-term data. In the OLE, DAWNZERA Q8W demonstrated a similar effect to Q4W over time, with a 94% total mean attack rate reduction from baseline across both dosing groups after one year.

OASISplus also included a switch cohort of patients who were previously treated with another prophylactic HAE medication (lanadelumab, berotralstat or C1-esterase inhibitor). Published data from the switch cohort indicate that patients who switched to donidalorsen from prior prophylactic treatments showed a 62% further reduction in mean monthly HAE attack rate from baseline, and 84% of patients surveyed reported a preference for donidalorsen.

"Hereditary angioedema can affect many aspects of daily life, and not knowing when an attack may occur can be difficult for patients and their families," said Michelle Cooper, President and Ontario Regional Director, HAE Canada Board of Directors. "We welcome the approval of DAWNZERA as another treatment option for Canadians living with HAE. Access to new therapies remains an important priority for the HAE community. This approval gives eligible patients another option to discuss with their healthcare providers."

Next Steps for Patient Access

CELYSTRA Pharma has initiated the reimbursement process with Canada's Drug Agency (CDA). In Québec, the company has also initiated the evaluation process with the Institut national d'excellence en santé et en services sociaux (INESSS), which makes recommendations to the government regarding coverage under Québec's public drug plan.

Two Health Canada Approvals in Nine Months

The approval of DAWNZERA follows Health Canada's approval of TRYNGOLZA^® (olezarsen) for familial chylomicronemia syndrome (FCS), giving CELYSTRA two approved products in nine months.

"CELYSTRA was founded to bring innovative therapies developed internationally to Canadian patients living with rare diseases," said Paul Lévesque, President and Chief Executive Officer of CELYSTRA Pharma. "Two Health Canada approvals in nine months represent an important milestone for CELYSTRA. With DAWNZERA, we are continuing to bring new treatment options to Canadians living with rare diseases. Our next priority is to work with healthcare professionals, governments and the HAE community to help expand access for patients across Canada."

DAWNZERA is expected to become commercially available in Canada in the coming months.

About Hereditary Angioedema (HAE)

Hereditary angioedema (HAE) is a rare and potentially life-threatening genetic condition characterized by recurrent attacks of severe swelling (angioedema) in various parts of the body, including the hands, feet, genitals, abdomen, face and throat. HAE attacks can result in significant functional impairment and reduced health-related quality of life and, in the case of laryngeal attacks, can be life-threatening.

About DAWNZERA^TM (donidalorsen)

DAWNZERA^TM (donidalorsen) is approved by Health Canada for the prevention of attacks of hereditary angioedema (HAE) in adult and pediatric patients 12 years of age and older. DAWNZERA is not intended for acute treatment of HAE attacks.

DAWNZERA is an RNA-targeted medicine designed to reduce the production of plasma prekallikrein (PKK), which plays an important role in activating inflammatory mediators associated with acute attacks of HAE.

DAWNZERA 80 mg is self-administered by subcutaneous injection once every four weeks (Q4W) or eight weeks (Q8W) using a single-dose, pre-filled autoinjector.

In Canada, DAWNZERA is marketed by CELYSTRA Pharma under licence from Ionis Pharmaceuticals.

Important Safety Information

For complete safety and prescribing information, please consult the DAWNZERA Product Monograph at https://www.celystrapharma.com/en/products/.

About CELYSTRA

CELYSTRA is a Québec-based Canadian biopharmaceutical company focused on identifying, acquiring and commercializing innovative therapies developed internationally. The company is committed to bringing these treatments to underserved patient populations in Canada and improving access to medicines that address unmet medical needs. See: www.celystrapharma.com

SOURCE CELYSTRA Pharma

Media contact: Serge Vallières, PRP, Senior Director, Corporate communications, NATIONAL Public Relations, Cell: [phone], [email protected]