Breakthrough Tracker record
A one-time in-vivo CRISPR treatment cut hereditary-angioedema attacks by 87% in a phase 3 trial
In the randomized phase 3 HAELO trial, 80 participants received one 50-mg intravenous dose of lonvoguran ziclumeran or placebo. From weeks 5 through 28, mean monthly attack rates were 0.26 versus 2.10, an estimated 87% relative reduction.
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- Stable ID
science-2026-hae-in-vivo-crispr-phase-3- Revision
science-2026-hae-in-vivo-crispr-phase-3.v1- Field
- Medicine · In-vivo genome editing
- Evidence
- Tier 1 · Peer reviewed: Yes
- Record state
- Current · Peer-reviewed phase 3 result
- Last checked
AI role
No substantive AI role was reported.
Record details
- Problem or result
- Hereditary angioedema causes unpredictable, potentially life-threatening swelling attacks and usually requires continuing preventive treatment.
- Authors
- Danny M. Cohn et al.; HAELO Investigators
- Institutions
- International HAELO clinical sites; Intellia Therapeutics
- Result date
- June 13, 2026
Why it matters
It is the first placebo-controlled phase 3 result to show a large clinical benefit from a single systemic CRISPR treatment that edits cells inside the body.
Limits
The treatment remains investigational, the rare-disease cohort was small, and median follow-up was about 7.5 months. Long-term durability, off-target editing, late adverse effects and permanent kallikrein-suppression risks remain unresolved; Intellia funded the study.
Sources
- Primary: NEJM primary paper
- Primary: ClinicalTrials.gov HAELO record
Correction and revision history
- 2026-06-13 — Phase 3 results published online in the New England Journal of Medicine.
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