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World’s First In Vivo CRISPR Gene Therapy Posts Positive Phase III Data, on Track for Approval Next Year

Recently, Intellia Therapeutics announced positive top-line results from the global Phase III HAELO clinical trial of lonvoguran ziclumeran (lonvo-z), its investigational CRISPR-based in vivo gene therapy for hereditary angioedema (HAE). The therapy met its primary endpoint and all key secondary endpoints, with a favorable safety and tolerability profile. Building on this milestone, Intellia has initiated a rolling submission of its Biologics License Application (BLA) to the U.S. Food and Drug Administration (FDA) and plans to commercialize the therapy in the U.S. in the first half of 2027.

The Phase III HAELO trial enrolled 80 patients, 52 of whom received lonvo-z and 28 received placebo. During the 6-month efficacy assessment period, a single infusion of lonvo-z reduced HAE attack rates by 87% compared with placebo, meeting the trial’s primary endpoint. For the key secondary endpoint, 62% of patients in the lonvo-z group remained attack-free and required no rescue therapy during the 6 months, versus only 11% in the placebo group.

Industry analysts noted that the impressive clinical data positions lonvo-z as “a highly attractive one-time treatment option”. Currently approved therapies for HAE (such as Takeda’s Takhzyro and Ionis’ Dawnzera) require long-term continuous administration, whereas lonvo-z delivers durable efficacy with a single dose, showing strong differentiation. In terms of safety, the most common adverse reactions observed in the lonvo-z group were infusion-related reactions, headache and fatigue; all adverse events were mild to moderate with no serious adverse events reported.