Intellia’s one-time CRISPR therapy lonvo-z reduced hereditary angioedema attacks by 87% in the Phase 3 HAELO trial, with 62% of patients remaining attack-free and therapy-free.
Written By: Dr. Preethi Putti, PharmD
Reviewed By: Pharmacally Editorial Team
Intellia Therapeutics presented detailed Phase 3 results from the HAELO trial (NCT06634420) of lonvo-z (formerly NTLA-2002) at EAACI 2026, with the findings simultaneously published in the New England Journal of Medicine.
HAE is a rare genetic disorder characterized by recurrent and potentially life-threatening swelling attacks that often require lifelong prophylactic treatment. Lonvo-z works by permanently inactivating the KLKB1 gene, reducing production of plasma kallikrein, a validated driver of HAE attacks. If approved, the therapy could become the first one-time CRISPR-based treatment for the disease.
Phase 3 HAELO Results
The global HAELO study enrolled 80 patients, randomizing 52 to lonvo-z and 28 to placebo. During the efficacy evaluation period (weeks 5–28), lonvo-z reduced mean monthly HAE attack rates by 87% compared with placebo (p<0.0001). Notably, 62% of treated patients remained both attack-free and free from prophylactic therapy during the six-month evaluation period, compared with 11% in the placebo arm.
Lonvo-z also reduced attacks requiring on-demand treatment by 89% and moderate-to-severe attacks by 91% (p<0.0001). All treated patients experienced reductions in attack frequency, with consistent benefit across age groups and regardless of prior long-term prophylaxis use.
Additional analyses showed that plasma kallikrein levels declined rapidly, reaching a stable reduction by week 5 and remaining suppressed through the February 2026 data cutoff. Investigators also reported clinically meaningful attack-rate reductions across all evaluated patient subgroups.
Quality-of-Life Improvements
Patients receiving lonvo-z achieved a 23.5-point reduction in Angioedema Quality of Life (AE-QoL) scores from baseline, compared with a 6.5-point reduction in the placebo group. The between-group difference of 17 points exceeded the six-point threshold considered clinically meaningful, highlighting substantial improvements in daily disease burden and patient wellbeing.
Safety Profile
Safety findings remained favorable. The most common treatment-emergent adverse events included infusion-related reactions, headache, fatigue, back pain, and upper respiratory tract infections. All reported events were mild to moderate, and no serious adverse events occurred in the lonvo-z arm through week 28.
Clinical Implications
Intellia President and Chief Executive Officer John Leonard said the Phase 3 findings provide “the first definitive evidence that in vivo CRISPR gene editing can deliver meaningful clinical benefit in a late-stage trial.” He also noted that all treated patients remained free from long-term prophylactic therapy as of the data cutoff.
Danny Cohn, M.D., Ph.D., a HAELO principal investigator at Amsterdam University Medical Center, said the prospect of long-term freedom from attacks and chronic medication could significantly change the treatment landscape for people living with HAE.
Regulatory Pathway
Intellia initiated a rolling Biologics License Application submission to the U.S. Food and Drug Administration in April 2026. The company expects regulatory approval and a U.S. commercial launch in the first half of 2027. If approved, lonvo-z could become the first one-time CRISPR-based treatment for hereditary angioedema.
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About the Writer
Dr.Preethi Putti, PharmD (LinkedIn) is a pharmaceutical researcher with experience in healthcare and pharmaceutical market research and competitive intelligence. She specializes in analyzing drug pipelines, clinical data, and industry trends and translating complex scientific data into clear and structured medical content. Strong foundation in clinical research, data interpretation, and evidence-based healthcare analysis. Committed to advancing a global career in clinical research and healthcare innovation.