Intellia Therapeutics' One-Time HAE Therapy Cuts Attacks 87% in Trial as FDA Decision Nears

Key Points

• Lonvo-z reduced HAE attacks by 87% versus placebo in the Phase 3 HAELO trial, and 62% of treated participants were attack-free during the efficacy period. Longer-term data showed attack rates remained below 0.5 per month through year four, with participants off preventive therapy at latest follow-up.
• The FDA accepted Intellia’s application for priority review and set a March 10, 2027 decision date; the agency does not currently plan an advisory committee meeting.
• If approved, Intellia expects initial patients to be treated in the second quarter after launch and a full commercial ramp by month 12. The company has not disclosed pricing and expects insurers may require step therapy.

Intellia Therapeutics NASDAQ: NTLA presented additional clinical data and outlined launch plans for lonvo-z, its investigational one-time gene-editing treatment for hereditary angioedema, as the company awaits a U.S. regulatory decision.

The Food and Drug Administration has accepted Intellia’s biologics license application for priority review and set a March 10, 2027, action date, President and CEO John Leonard said at the company’s investor event. The agency does not currently plan to hold an advisory committee meeting on the application, he said.

Hereditary angioedema, or HAE, is a rare genetic condition that causes unpredictable, painful and potentially life-threatening swelling attacks. Current treatment includes long-term preventive medications and drugs taken as needed during attacks, according to Dr. Marc Riedl, professor of medicine and clinical director of the HAEA Angioedema Center at UC San Diego.

Clinical Data Show Reduced Attacks

Chief Medical Officer Dr. Jing Marantz said lonvo-z is designed to permanently inactivate the KLKB1 gene, reducing production of proteins involved in the pathway that causes swelling. In the placebo-controlled Phase 3 HAELO trial, the treatment produced an 87% mean reduction in attacks compared with placebo, and 62% of treated participants were attack-free during the efficacy observation period.

Among 35 participants assigned to lonvo-z who had been taking long-term preventive treatment before screening, the attack rate fell 81% during weeks five through 28 after dosing, compared with their reported rate while on prior treatment. In that group, 63% were attack-free during the observation period, while 20% had reported complete attack control as their best response to prior preventive therapy, Marantz said.

An integrated analysis covered 93 participants who received the proposed commercial dose across Phase 1, 2 and 3 studies, with up to four years of follow-up for some. Marantz said average attack rates fell from more than three per month at baseline to below 0.5 by month two and remained below that level through year four. All 93 participants were off long-term preventive therapy at their latest follow-up.

Most reported adverse events, including infusion-related reactions, headache and fatigue, occurred within the first month after treatment, Marantz said. She said no long-term risks had been observed through the data cutoff.

Patient Experience and Treatment Burden

Riedl said some patients do well on current medications, while others continue to experience attacks, anxiety and difficulties maintaining insurance coverage. He said physicians and patients typically decide on treatment together.

Dr. Danny Cohn, an internist at Amsterdam University Medical Center, described interviews with 23 participants from earlier lonvo-z trials. All 23 considered their HAE well-controlled after treatment, compared with 48% who said it was well-controlled beforehand. Median follow-up at the time of the interviews was nearly 2.5 years, he said.

Riedl cautioned during the question-and-answer session that some patients may want to see more information about safety and durability before deciding on treatment. He also said he would want patients to retain access to rescue medication in case of breakthrough attacks.

Launch and Access Plans

Senior Vice President of Commercial Maria Natale said Intellia estimates that about 7,500 people in the U.S. are treated for type 1 or type 2 HAE. In company research involving more than 150 health care professionals, 88% said they would prescribe a one-time treatment with lonvo-z’s profile to at least one patient. In a separate survey of more than 150 patients, 83% said they were likely to ask their physician about it.

Intellia has not disclosed a price. Natale said the company expects insurers to use step-therapy requirements, which could require some patients to try a preventive medication before accessing lonvo-z.

If the treatment is approved, Intellia expects the first wave of patients to be treated in the second quarter after launch, with revenue recognition beginning during that period. The company is preparing a network of authorized treatment centers and expects to reach a full commercial ramp by month 12, Natale said. Leonard declined to predict the shape of the sales curve beyond that point.

About Intellia Therapeutics (NASDAQ:NTLA)

Intellia Therapeutics, Inc. is a clinical-stage biotechnology company focused on developing genome-editing treatments for serious diseases. Founded in 2014 and headquartered in Cambridge, Massachusetts, the company uses CRISPR/Cas9 technology to make targeted changes to DNA. Its research includes in vivo therapies, which are designed to edit genes inside a patient's body, and ex vivo approaches, which involve modifying cells outside the body before they are returned to the patient. Intellia's investigational programs have included treatments for transthyretin amyloidosis and hereditary angioedema.

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