Full Phase III data for lonvoguran ziclumeran (lonvo-z) — published simultaneously in the New England Journal of Medicine and presented at the European Academy of Allergy & Clinical Immunology Annual Congress — show that a single infusion reduced moderate and severe hereditary angioedema attacks by 91% over six months, reinforcing the case for lonvo-z as the first in vivo CRISPR therapy to reach a regulatory filing. For the Massachusetts-based Intellia Therapeutics (Nasdaq: NTLA), the data matter beyond HAE: they represent the first complete Phase III dataset for any in vivo gene editing candidate, arriving as the company advances a rolling biologics license application (BLA) with the US FDA and targets a US commercial launch in the first half of 2027.
The HAELO trial is a randomized, double-blind, placebo-controlled Phase III study that enrolled 80 adults and adolescents with Type I or Type II HAE, with 52 receiving a single 50 mg infusion of lonvo-z and 28 receiving placebo. The primary endpoint — previously reported — showed an 87% reduction in mean monthly attack rate during the six-month efficacy evaluation period (weeks 5–28), with a rate of 0.26 in the lonvo-z arm versus 2.10 in the placebo arm (p<0.0001). The data presented at EAACI filled in the remaining key secondary endpoints: attacks requiring on-demand treatment fell 89% (p<0.0001); moderate and severe attacks fell 91% (p<0.0001); and the validated Angioedema Quality of Life score improved by 17 points in the lonvo-z arm versus placebo (p<0.0001), far exceeding the 6-point threshold considered clinically meaningful. A total 62% of lonvo-z patients were entirely attack-free and free from long-term prophylaxis for the full six-month period, compared with 11% on placebo. Notably, 20% of enrolled patients had reported zero attacks as their best-ever response to prior prophylactic therapy — yet all patients in the lonvo-z arm experienced attack-rate reductions from baseline. All adverse events were mild or moderate; no serious adverse events were reported in the lonvo-z arm.
Competitive context