Intellia’s In-Vivo CRISPR Therapy Shows 87% Reduction in Hereditary Angioedema Attacks

Intellia Therapeutics reported that a 50-mg infusion of lonvoguran ziclumeran (lonvo-z) met the primary endpoint of the Phase 3 HAELO trial, cutting hereditary angioedema attacks by 87 % versus placebo over a six-month efficacy window.

BioPharmaDive

HAE is an autosomal-dominant disorder affecting ~1 in 50,000 people, causing unpredictable swelling due to excess bradykinin. Lonvo-z employs CRISPR/Cas9 to inactivate the KLKB1 gene in liver cells, delivering the first in-vivo gene-editing therapy for any disease.

Pharmaphorum

Eighty patients (52 lonvo-z, 28 placebo) were enrolled; 49 % were U.S. participants and 71 % entered on long-term prophylaxis, discontinued before dosing. Mean monthly attacks fell to 0.26 in the treatment arm versus 2.10 in placebo (p < 0.0001). Sixty-two percent of treated patients were attack-free and off all prophylaxis for six months, compared with 11 % of controls.

Intellia Therapeutics Reports Positive Phase 3 Results in Hereditary Angioedema, Marking a Global First for In Vivo Gene Editing

CEO John Leonard called the results a “profound milestone” for Intellia, CRISPR and the HAE community, emphasizing the prospect of freeing patients from chronic prophylaxis. Investigator Aleena Banerji noted the therapy’s potential to eliminate ongoing medication. Intellia has filed a rolling BLA and holds orphan-drug, RMAT and PRIME designations, targeting U.S. launch in 2027.

Pharmaphorum

Analysts caution that the HAE market already hosts several approved prophylactics, limiting lonvo-z’s sales upside; peak revenue is projected near $500 million. Safety concerns persist, especially regarding off-target edits and long-term durability, echoing past gene-therapy setbacks.

BioPharmaDive

The six-month data show no serious adverse events, but durability beyond this period and the effect of stopping prior prophylaxis remain unreported, leaving long-term efficacy uncertain.

Intellia Therapeutics Reports Positive Phase 3 Results in Hereditary Angioedema, Marking a Global First for In Vivo Gene Editing

• “When you think about where we started with Crispr, just 12 years ago with some of the fundamental insights, I think there was a lot of talk about what might be possible, and we've had reports along the way in terms of milestones, but this is the first Phase 3 data in any indication with in vivo Crispr where you're actually changing a gene that causes disease,” — John Leonard, Intellia Therapeutics

CNBC

• “As the first Phase 3 data reported for an in vivo gene editing therapy, today’s HAELO results represent a profound milestone for Intellia, the broader CRISPR and precision medicine fields and, most importantly, the HAE community,” — John Leonard, Intellia Therapeutics

Intellia Therapeutics Reports Positive Phase 3 Results in Hereditary Angioedema, Marking a Global First for In Vivo Gene Editing

• “The results we are seeing from lonvo-z demonstrate its potential to eliminate the need for chronic medication and related challenges.” — Aleena Banerji, Harvard Medical School

Pharmaphorum

• “This “clean safety” addresses a key concern among investors on the program and company “as a whole,” wrote Leerink Partners analyst Mani Foroohar.” — Mani Foroohar, Leerink Partners

BioPharmaDive

Intellia has initiated a rolling biologics license application with the FDA, aiming to complete filing in the second half of 2026 and seek approval for a U.S. launch in early 2027. Additional data will be presented at the EAACI Congress in Istanbul (June 12-15, 2026).

Intellia Therapeutics Reports Positive Phase 3 Results in Hereditary Angioedema, Marking a Global First for In Vivo Gene Editing