biology · eu
Phase 3 Trial of In Vivo CRISPR Therapy Reports Positive Results, With Sharp Drop in Hereditary Angioedema Attacks
lonvoguran ziclumeran reduced attack rates versus placebo in an international, double-blind phase 3 trial; the study has been published in NEJM, but long-term efficacy, rare risks, and regulatory review still require further confirmation.
Amsterdam University Medical Center said in a release via EurekAlert that a phase 3 clinical trial of an in vivo CRISPR gene-editing therapy for hereditary angioedema produced positive results. The therapy, lonvoguran ziclumeran, is administered as a single intravenous infusion, and the research team said this is the first completed large-scale, double-blind, international phase 3 trial of an in vivo CRISPR treatment.
According to the release, the trial enrolled 80 patients with hereditary angioedema, who were randomly assigned to receive the CRISPR therapy or placebo. The primary evaluation period ran from week 5 to week 28 after dosing, during which the treatment group had 87% fewer attacks than the placebo group. The results were published in the New England Journal of Medicine (NEJM) on June 13, 2026, and presented at the European Academy of Allergy and Clinical Immunology annual meeting.
Hereditary angioedema is a rare disease in which patients experience recurrent swelling that can affect the skin, gastrointestinal tract, or airways; if it involves the throat, it may pose an acute danger. Existing treatments can be used for prevention or management of acute attacks, but patients may still face the burdens of long-term medication, sudden attacks, and reduced quality of life.
The release showed that among patients who received lonvoguran ziclumeran, 62% had no further attacks without maintenance treatment; the proportion in the placebo group was 11%. Secondary endpoints also favored the treatment group, including an 89% reduction in the need for on-demand medication, a 91% reduction in moderate-to-severe attacks, and a greater improvement in quality-of-life scores than in the placebo group.
On safety, Amsterdam University Medical Center said the treatment was generally well tolerated. Common adverse reactions included mild infusion-related reactions, headache, fatigue, and back pain, all of which resolved quickly; no serious adverse events were reported in the treatment group. However, currently public information comes mainly from an institutional press release and summary trial descriptions, and the population composition, follow-up duration, statistical methods, and adverse-event details in the full paper still need to be examined.
If these results are accepted by regulators, they could become an important milestone for bringing in vivo CRISPR therapies to market. What still requires cautious assessment is that the main observation period in the phase 3 trial was less than half a year, and the durability of gene-editing treatment, extremely rare side effects, responses across different patient populations, and how post-marketing monitoring will be conducted will all be key points for subsequent evaluation.