FDA grants lonvo-z priority review

Lonvo-z is designed to inactivate the kallikrein B1 gene, KLKB1, permanently lowering kallikrein production and thereby preventing the inflammatory swelling attacks characteristic of hereditary angioedema. If approved, it could become the first authorised in vivo CRISPR-Cas therapy and the first one-time treatment for the disorder.

The application is supported by Intellia’s global HAELO trial, which enrolled 80 adults and adolescents aged at least 16 years with type 1 or type 2 hereditary angioedema. Participants received either a single 50 mg dose of lonvo-z or placebo.

Between weeks five and 28, lonvo-z reduced the mean monthly attack rate by 87%. During the six-month evaluation period, 62% of treated participants remained free from both attacks and hereditary angioedema therapy, compared with 11% in the placebo group.

Reported adverse events were mild or moderate, with no serious adverse events in the lonvo-z arm through week 28. Longer-term efficacy and safety remain under evaluation. The FDA’s target date for deciding on the application is 10 March 2027.

The news was reported in a press release by Intellia Therapeutics on 8 September 2026.