Study summary

A one-time CRISPR treatment cut swelling attacks by 87% in phase 3

HAELO trial (lonvo-z) · 80 people, phase 3 · Reported April 2026, published in NEJM; rolling FDA application under way

What was tested

Lonvoguran ziclumeran (lonvo-z, formerly NTLA-2002), a single infusion that uses CRISPR to permanently switch off the KLKB1 gene in the liver, lowering kallikrein, against placebo.

What they found

• Attack rates fell 87% compared with placebo.
• Just over 60% were completely attack-free, vs 11% with placebo.

What it means

Would be the first in-body gene-editing treatment approved for any disease, potentially ending the need for lifelong preventive drugs.