Hereditary angioedema (HAE) patients receiving a single infusion of the investigational CRISPR-based gene-editing therapy lonvoguran ziclumeran (lonvo-z) experienced an 87% reduction in mean monthly attack rates compared with placebo over a six-month evaluation period, Intellia Therapeutics reported at the European Academy of Allergy and Clinical Immunology (EAACI) Annual Congress 2026 in Istanbul on June 13, 2026. The results were simultaneously published in the New England Journal of Medicine (DOI: 10.1056/NEJMoa2600931).

About the therapy

Lonvo-z (INN: lonvoguran ziclumeran) is an investigational in vivo gene-editing treatment based on CRISPR/Cas9 technology designed to permanently silence the KLKB1 gene, which encodes plasma kallikrein B1. By reducing kallikrein activity and downstream bradykinin production, the single-dose treatment aims to address the root cause of HAE attacks. Lonvo-z has not been approved by any regulatory agency.

Trial design

The Phase 3 HAELO trial enrolled 80 patients with Type 1 or Type 2 HAE, randomised 2:1 to receive a single intravenous dose of lonvo-z (n=52) or placebo (n=28). The primary efficacy evaluation period ran from week 5 through week 28 post-dose.

Efficacy (all figures per the company)

  • Mean monthly attack rate: 0.26 (lonvo-z) vs. 2.10 (placebo) — 87% reduction (95% CI: −93% to −78%; P<0.001)
  • Attack-free patients: 62% (lonvo-z) vs. 11% (placebo) — odds ratio 12.8 (95% CI: 3.5–47.6; P<0.0001)
  • Reduction in attacks requiring on-demand treatment: 89%, the company said
  • Reduction in moderate-to-severe attacks: 91%, the company said

These figures are derived from Intellia’s press release and have not been independently verified by this publication from the primary NEJM paper; readers should refer to the published manuscript for the complete data.

Safety (per the company)

All treatment-emergent adverse events were mild to moderate in severity; no serious adverse events were observed.

Regulatory status

Lonvo-z holds Orphan Drug and Regenerative Medicine Advanced Therapy (RMAT) designations from the FDA. A rolling Biologics License Application (BLA) has been initiated, the company said, with target BLA submission completion in 2H 2026 and potential US launch in 1H 2027 — timelines that are subject to regulatory review and not guaranteed.

Lonvo-z is an investigational therapy that has not been approved by the FDA or any other regulatory agency. This article does not constitute an endorsement of this therapy or a recommendation to seek or alter treatment.