Ionis Pharmaceuticals announced on November 12, 2026, 2-year data from the OASISplus study showing that donidalorsen (Dawnzera) kept hereditary angioedema (HAE) attack rates down, including in patients who switched from other long-term prophylactic therapies.¹ The data are being presented at the 2026 American College of Allergy, Asthma & Immunology (ACAAI) Annual Scientific Meeting in Phoenix, Arizona, which is running November 12–16.¹
Key facts
- Drug: donidalorsen (Dawnzera; Ionis Pharmaceuticals)
- Class: RNA-targeted medicine targeting plasma prekallikrein
- Indication: Prophylaxis of HAE attacks (patients 12 years of age and older)
- Trial: OASISplus (NCT05392114); open-label extension and switch cohorts
- OLE result: 95% attack rate reduction over 2 years (n=83)
- Switch result: 71% attack rate reduction vs prior prophylaxis (n=64)
- Dosing: Every 4 or 8 weeks; post hoc every-8-week effect consistent
- Retention: 84% (OLE) and 80% (switch) at 2 years
- Safety: No new signals; no serious TEAEs related to treatment
- Presentation: ACAAI 2026 Annual Scientific Meeting, Phoenix, Arizona
“These data demonstrate that DAWNZERA achieved durable efficacy and safety, not only when dosed every four weeks but also every eight weeks,” said Kenneth Newman, MD, senior vice president of clinical development at Ionis, in the release.¹
What did the 2-year data show?
The OASISplus open-label extension (OLE) cohort enrolled adult and adolescent patients continuing from the phase 3 OASIS-HAE pivotal trial. They received donidalorsen every 4 weeks or every 8 weeks.¹ After 2 years, 84% of patients remained in the study, and patients had a 95% overall reduction from baseline in HAE attack rates across both dosing groups (n=83).¹ At year 1, the peer-reviewed OLE analysis reported mean attack rate reductions from OASIS-HAE baseline of 94% with every-4-week dosing and 95% with every-8-week dosing.²
In the switch cohort, patients previously treated with lanadelumab, C1-esterase inhibitor, or berotralstat moved to donidalorsen using a predefined protocol.¹ After 2 years, 80% remained in the cohort, and the overall HAE attack rate was 71% lower than their baseline on prior prophylactic therapy (n=64).¹
A post hoc analysis found that patients who started the OLE on donidalorsen every 8 weeks kept a 95% overall attack rate reduction over 2 years, consistent with patients dosed every 4 weeks.¹
What was the long-term safety profile?
No new safety signals were seen across the analyses.¹ Most treatment-emergent adverse events (TEAEs) were mild or moderate, and there were no serious TEAEs related to donidalorsen.¹ In the year 1 OLE analysis, 27% of patients reported treatment-related TEAEs, none of them serious, and injection-site reactions were the most common.²
How does donidalorsen work?
Donidalorsen is an RNA-targeted medicine designed to target plasma prekallikrein, which plays an important role in activating inflammatory mediators linked to acute HAE attacks.¹ It is approved for prophylaxis to prevent HAE attacks in patients 12 years of age and older.¹ In the pivotal OASIS-HAE trial of 90 patients, the mean attack rate from week 1 to week 25 was 81% lower with every-4-week dosing and 55% lower with every-8-week dosing than with placebo.³
