Intellia starts FDA submission for in vivo Crispr therapy lonvo-z as one-time angioedema treatment

Intellia Therapeutics has initiated a rolling submission of a Biologics License Application (BLA) to the US FDA for lonvoguran ziclumeran, known as lonvo-z, seeking approval as a one-time treatment for hereditary angioedema (HAE). The filing represents what Intellia describes as the first BLA submission for an in vivo CRISPR-based gene editing therapy across any indication.

The rolling BLA, enabled by the Regenerative Medicine Advanced Therapy (RMAT) designation the FDA previously granted to lonvo-z, allows Intellia to submit completed sections of the application on an ongoing basis rather than as a single package. Intellia said it anticipates completing the full submission in the second half of 2026. If the FDA accepts the filing, the agency will determine whether to grant priority review and assign a target action date. The company said it plans a commercial launch in Q1 or Q2 of 2027, contingent on approval.

The BLA is supported in part by data from the Phase III HAELO clinical trial, for which Intellia simultaneously reported positive topline results on April 27, 2026. The company said the trial met its primary endpoint and all key secondary endpoints, with a single dose of lonvo-z producing freedom from both HAE attacks and the need for ongoing therapy in most patients during the six-month primary observation period. The trial examined lonvo-z in patients with HAE, a rare genetic disease affecting an estimated one in 50,000 people, characterized by unpredictable and potentially life-threatening swelling episodes driven by excess bradykinin production.

Lonvo-z is designed to inactivate the kallikrein B1 gene (KLKB1) in hepatocytes, permanently reducing kallikrein and bradykinin levels following a single outpatient administration. The approach is mechanistically distinct from all currently approved HAE therapies, which require chronic dosing — whether subcutaneous injections every two to four weeks, daily oral tablets, or twice-weekly infusions. The HAE treatment landscape expanded considerably in 2025 with three new FDA approvals: garadacimab (Andembry), which targets Factor XIIa; sebetralstat (Ekterly), the first oral on-demand therapy targeting plasma kallikrein; and donidalorsen, an antisense oligonucleotide that reduces prekallikrein synthesis. Each of these, however, requires indefinite administration. Lonvo-z, if approved, would be the first therapy in HAE designed to eliminate the need for ongoing treatment after a single dose.

The filing also positions lonvo-z within a broader question in gene medicine: whether in vivo CRISPR editing can translate from early clinical data into a regulatory approval. Intellia participated in the FDA's Chemistry, Manufacturing, and Controls Development and Readiness Pilot program, which facilitates ongoing dialogue between sponsors and FDA review staff on manufacturing strategy — a pathway the company said was intended to support submission readiness and earlier patient access.

The unmet need lonvo-z targets is well-documented. Despite an expanding set of approved prophylactic agents, breakthrough attacks persist in a proportion of HAE patients on long-term prophylaxis, and chronic treatment burden — including injection fatigue and adherence demands — remains a recognized limitation. The HAELO trial results, if confirmed in the full dataset, would represent the first clinical evidence that permanent KLKB1 inactivation via CRISPR can sustain attack freedom over a defined observation period in HAE patients.

The submission follows the first wave of CRISPR medicine approvals, led by Casgevy (exagamglogene autotemcel) from Vertex Pharmaceuticals and CRISPR Therapeutics, an ex vivo CRISPR/Cas9-edited autologous cell therapy approved for sickle cell disease and transfusion-dependent beta thalassemia in 2023. Unlike Casgevy, which involves editing a patient’s cells outside the body before reinfusion, lonvo-z is delivered in vivo and is intended to edit hepatocytes directly after a single outpatient administration. That distinction makes the filing a potentially important regulatory test case for systemic, in vivo CRISPR therapeutics, rather than for CRISPR gene editing as a category overall.

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