Cambridge, Mass. — Intellia Therapeutics, Inc. said it reported additional positive results from the global Phase 3 HAELO clinical trial of lonvoguran ziclumeran, or lonvo-z, in patients with hereditary angioedema.
The data were presented in a late-breaking oral session at the European Academy of Allergy & Clinical Immunology Annual Congress 2026 in Istanbul, Türkiye, and were simultaneously published in the New England Journal of Medicine.
Lonvo-z, formerly known as NTLA-2002, is an investigational in vivo CRISPR gene editing therapy being developed as a potential one-time treatment for hereditary angioedema, a rare genetic disease marked by severe, recurring and unpredictable inflammatory attacks that can be painful, debilitating and life-threatening.
As previously announced, HAELO met its primary endpoint, showing an 87% reduction in mean monthly attacks in the lonvo-z arm compared with placebo during the efficacy evaluation period from weeks five to 28. In addition, 62% of patients who received lonvo-z were entirely attack free and therapy free during the six-month efficacy evaluation period, compared with 11% of patients in the placebo arm.
Intellia also reported that lonvo-z reduced the monthly rate of attacks requiring on-demand treatment by 89% compared with placebo and reduced the monthly rate of moderate or severe attacks by 91%. Patients who received lonvo-z also showed a greater improvement in Angioedema Quality of Life scores compared with placebo.
The company said lonvo-z demonstrated favorable safety and tolerability. The most common treatment-emergent adverse events during the primary observation period that occurred more often with lonvo-z than placebo were infusion-related reaction, headache, fatigue, back pain and upper respiratory tract infection. All reported treatment-emergent adverse events were mild or moderate, and no serious adverse events were observed in the lonvo-z arm.
“These are the first Phase 3 results to deliver on the much-heralded promise of in vivo CRISPR gene editing,” said John Leonard, M.D., Intellia President and Chief Executive Officer. “Regardless of age or prior use of long-term prophylaxis therapies, it was observed that a single lonvo-z treatment significantly reduced HAE attacks for all patients during the efficacy evaluation period, with all patients remaining LTP free as of the data cutoff. We thank the many patients, physicians and caregivers who participated in HAELO and are excited to be advancing this highly differentiated candidate toward a potential approval.”
Danny Cohn, M.D., Ph.D., internist in the Department of Vascular Medicine at Amsterdam Cardiovascular Sciences, Amsterdam University Medical Center, and a HAELO principal investigator, said the findings could represent an important advance for patients.
“As a clinician who has witnessed patients struggle with the unpredictability and emotional toll of HAE, the prospect of offering lasting freedom from attacks and chronic medication with a one-time treatment is incredibly exciting. These results give me confidence that many patients will soon have the potential to enjoy a normal life,” Cohn said.
The presentation and publication also included supplemental demographics, data and analyses. Intellia said the data showed mean monthly attack rates among patients receiving lonvo-z remained well below prescreening rates through the Feb. 10, 2026, data cutoff, while patients had previously been receiving standard-of-care therapy. The company also said all patients in the lonvo-z arm experienced attack-rate reductions from baseline during weeks five to 28, with meaningful reductions observed across evaluated subgroups.
A rolling biologics license application submission for lonvo-z was initiated with the U.S. Food and Drug Administration in April. Intellia said it continues to anticipate regulatory approval and a U.S. launch in the first half of 2027.
Lonvo-z is designed to permanently lower kallikrein by inactivating the kallikrein B1 gene with a single dose. The therapy has received Orphan Drug and RMAT designations from the FDA, an Innovation Passport from the U.K. Medicines and Healthcare products Regulatory Agency, PRIME designation from the European Medicines Agency and Orphan Drug Designation from the European Commission.
