Otsuka Pharmaceutical Co., Ltd. (Otsuka) announces that on November 14 the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) issued a positive opinion recommending granting of marketing authorization of the drug candidate donidalorsen (generic name) for the routine prevention of recurrent attacks of HAE in adults and adolescents aged 12 years and older. Following this CHMP recommendation, a final decision on approval is expected from the European Commission (EC) within 67 days.

Donidalorsen was developed by Ionis Pharmaceuticals, Inc. (Ionis), a leader in RNA-targeted medicines based in Carlsbad, California, as a prophylaxis to prevent attacks of HAE. Otsuka submitted a Marketing Authorization Application (MAA) to the EMA for donidalorsen, targeting the prevention of recurrent HAE attacks in adults and adolescents aged 12 years and older, and the application was accepted in December 2024.

HAE is a rare, chronic and potentially life-threatening genetic condition that involves recurrent, unpredictable attacks of swelling episodes that can affect the extremities, face, abdomen, genitals and even the larynx, posing serious risk for patients. Edema of the GI tract and larynx can cause abdominal pain and breathlessness, and in severe cases, may be life-threatening. This disease is rare, occurring in approximately 1 in 50,000 people globally*, and is thought to have no racial predilection; approximately 75 percent of cases are familial. (Guideline for HAE 2023 by the Japanese Association for Complement Research.)

Donidalorsen is an RNA-targeted treatment designed to precisely target and reduce the production of prekallikrein (PKK) in the liver, interrupting the pathway that leads to HAE attacks. In the Phase 3 OASIS-HAE and OASISplus studies, donidalorsen delivered positive data across multiple measures of disease including significant and sustained reduction in mean monthly HAE attack rate, including when self-administered via autoinjector.

Otsuka entered into a licensing agreement with Ionis in December 2023 in which Otsuka acquired exclusive rights to commercialize donidalorsen in Europe. Subsequently, in June 2024, Otsuka acquired exclusive commercial rights covering the Asia-Pacific region, including Japan.

Otsuka remains committed to delivering donidalorsen to HAE patients in Europe and Asia, aiming to help address unmet medical needs.

About Otsuka
Otsuka Pharmaceutical Co., Ltd. is a total healthcare company that focuses on each individual's potential to enhance their well-being. Our medical-related business provides treatments and diagnostics for both physical and mental health. Our nutraceutical business supports daily health maintenance and improvement. Otsuka's unique products and services are based on scientific evidence, under the guidance of our corporate philosophy: Otsuka-people creating new products for better health worldwide. For further information, please visit www.otsuka.co.jp/en/