Lonvo-z Advances Toward Approval as First In Vivo CRISPR Therapy for Hereditary Angioedema

Intellia Therapeutics has initiated a rolling biologics license application (BLA) submission to the FDA for lonvoguran ziclumeran (lonvo-z), an investigational one-time CRISPR-based gene editing therapy for hereditary angioedema (HAE), following phase 3 data showing substantial reductions in attack rates and treatment burden.¹

The application is supported by topline results from the global phase 3 HAELO trial, which met its primary and all key secondary endpoints, marking what could become the first regulatory submission for an in vivo CRISPR-based therapy.²

“If approved, lonvo-z will become the world’s first in vivo CRISPR-based gene editing therapy,” said John Leonard, MD, president and chief executive officer of Intellia, in a statement.¹

“The promising results from HAELO reinforce our conviction that lonvo-z could revolutionize how HAE is treated for many patients, with the potential to free most of them from both attacks and the need for ongoing therapy with just one dose.”²

HAE is a rare genetic disorder characterized by recurrent, unpredictable swelling attacks driven by dysregulation of the kallikrein-kinin pathway. Despite the availability of prophylactic and on-demand therapies, many patients continue to experience breakthrough attacks and must adhere to chronic treatment regimens, often requiring frequent injections or infusions.¹

Lonvo-z is designed to address this unmet need through a one-time, in vivo CRISPR/Cas9 gene editing approach that inactivates the KLKB1 gene, leading to sustained reductions in kallikrein and downstream bradykinin production.¹ By targeting the underlying disease biology, the therapy aims to provide durable control of attacks without the need for ongoing treatment.

Phase 3 HAELO Data Demonstrate Significant Reduction in Attacks

The phase 3 HAELO study, a randomized, double-blind, placebo-controlled trial, enrolled 80 patients with type I or II HAE, with 52 receiving lonvo-z and 28 assigned to placebo.² Nearly half of participants were enrolled in the United States, and 71% were receiving long-term prophylaxis prior to study entry.

During the 6-month primary efficacy period, treatment with lonvo-z resulted in an 87% reduction in HAE attacks compared with placebo, with mean monthly attack rates of 0.26 versus 2.10, respectively (P < .0001). In addition to meeting the primary endpoint, the trial achieved all key secondary endpoints. Notably, 62% of patients treated with lonvo-z were both attack-free and off long-term prophylaxis during the evaluation period, compared with 11% of patients in the placebo group (P < .0001).²

Safety findings were favorable, with treatment-emergent adverse events primarily consisting of mild to moderate infusion-related reactions, headache, and fatigue. No serious adverse events were reported in the treatment arm during the primary observation period.

“The results we are seeing from lonvo-z demonstrate its potential to eliminate the need for chronic medication and related challenges,” Aleena Banerji, MD, a principal investigator on the study, said in a statement.² “If approved as a one-time treatment, I would expect lonvo-z to be an appealing option for many patients.”

Durability Data Further Support One-Time Treatment Approach

These phase 3 findings build on earlier clinical data demonstrating sustained efficacy following a single dose. In a phase 1/2 study published in the Journal of Allergy and Clinical Immunology, lonvo-z achieved a 95% mean reduction in monthly attack rates, with 93% of patients remaining both attack-free and off long-term prophylaxis at follow-up.

Patients in that study maintained these benefits for a median of approximately 10 months, with some individuals followed for up to 2 years, suggesting durable disease control after a single administration. The safety profile remained consistent across cohorts, with predominantly mild adverse events such as infusion-related reactions, fatigue, and headache.³

Regulatory Pathway and Broader Implications

Lonvo-z has received multiple regulatory designations, including Regenerative Medicine Advanced Therapy (RMAT), Orphan Drug designation in the United States and Europe, and PRIME designation from the European Medicines Agency.¹ The RMAT designation allows for a rolling BLA submission, enabling ongoing dialogue with the FDA and potential acceleration of the review process.

Intellia expects to complete the BLA submission in the second half of 2026, with a potential U.S. launch anticipated in the first half of 2027 if approved.¹

From a broader clinical perspective, the development of lonvo-z represents a potential paradigm shift in the management of HAE. While kallikrein inhibition is an established therapeutic strategy, current agents require chronic administration and ongoing adherence. A one-time gene editing approach could fundamentally change long-term disease management, particularly if durability and safety are confirmed in longer-term follow-up.

If approved, lonvo-z would represent not only a new treatment option for HAE but also a landmark advancement for in vivo gene editing, potentially opening the door for similar approaches across a range of genetic and immunologic disorders.

REFERENCES
1. Intellia Therapeutics. Intellia initiates rolling biologics license application for lonvoguran ziclumeran in hereditary angioedema. News release. April 27, 2026. https://ir.intelliatx.com/news-releases/news-release-details/intellia-therapeutics-initiates-rolling-submission-biologics
2. Intellia Therapeutics. Positive phase 3 HAELO results for lonvoguran ziclumeran in hereditary angioedema. News release. April 27, 2026. https://ir.intelliatx.com/news-releases/news-release-details/intellia-therapeutics-reports-positive-phase-3-results
3. Magerl M, Gurugama P, Katelaris C, et al. Long-term durability and safety of lonvoguran ziclumeran in patients with hereditary angioedema. J Allergy Clin Immunol. 2025;157(2).