CONFIDENTIAL *** Intellia Therapeutics Reports Positive Phase 3 Results in Hereditary (Form 8-K)

*** CONFIDENTIAL ***

Intellia Therapeutics Reports Positive Phase 3 Results in Hereditary

Angioedema, Marking a Global First for In Vivo Gene Editing

CAMBRIDGE, Mass., April 27, 2026 - Intellia Therapeutics, Inc. (Nasdaq: NTLA), a leading biopharmaceutical company focused on revolutionizing medicine leveraging CRISPR gene editing and other core technologies, today announced positive topline results from the global Phase 3 HAELO clinical trial of lonvo-z (formerly known as NTLA-2002) in hereditary angioedema (HAE). HAE is a rare genetic condition in which patients experience recurrent and potentially life-threatening swelling (angioedema) attacks in various parts of their body, including the face, upper airway, abdomen and extremities due to an overproduction of bradykinin. Designed as a one-time treatment that is administered in an outpatient setting, lonvo-z is an in vivo CRISPR gene editing candidate that is intended to inactivate the kallikrein B1 (KLKB1) gene to permanently lower kallikrein and bradykinin levels.

Intellia separately announced today that it has initiated a rolling BLA submission to the FDA to seek regulatory approval. The company is preparing for a potential U.S. launch of lonvo-z in the first half of 2027.

"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," said John Leonard, M.D., Intellia President and Chief Executive Officer. "For those patients who have spent years battling unpredictable breakthrough swelling attacks, anxiety about their next attack or the many burdens associated with chronic prophylactic treatment, lonvo-z represents a potential paradigm shift in treatment. These data affirm lonvo-z's potential, with one dose, to offer prolonged freedom from both attacks and the need for ongoing therapy."

"We extend our deep gratitude to the many patients, caregivers and clinicians who have helped advance gene editing science by participating in our clinical trials. It is because of their contribution that we are advancing toward our first potential approval, with the goal of making lonvo-z available to U.S. patients in the first half of 2027," Dr. Leonard concluded.

HAELO Topline Results

HAELO is a randomized, double-blind, placebo-controlled Phase 3 trial designed to evaluate the efficacy and safety of a one-time 50 milligram dose of lonvo-z in adults and adolescents aged 16 years and older with Type I or Type II HAE. Key endpoints of the trial focused on the number of HAE attacks experienced by patients, quality of life, safety and tolerability.

A total of 80 patients were enrolled, with 52 receiving lonvo-z and 28 receiving placebo. Of the total population, 49% of patients were enrolled in the United States and 71% were on long-term prophylaxis (LTP) therapy at study entry. Patients on LTP were required to discontinue those therapies in the weeks prior to dosing.

Key findings from HAELO include:

Additional clinical data from HAELO will be presented at the 2026 European Academy of Allergy and Clinical Immunology Congress (EAACI), taking place June 12-15 in Istanbul, Türkiye (abstract #100217).

"Despite the availability of several HAE treatments, many patients continue to experience significant burdens related to the disease, including breakthrough attacks and challenges associated with chronic treatment," said Aleena Banerji, M.D., Professor at Harvard Medical School, Director of Clinical Care, Center for Drug and Vaccine Allergy at Massachusetts General Hospital, and a HAELO principal investigator. "The results we are seeing from lonvo-z demonstrate its potential to eliminate the need for chronic medication and related challenges. If approved as a one-time treatment, I would expect lonvo-z to be an appealing option for many patients."

Webcast Information

The company will host a conference call and webcast today at 8:00 a.m. ET to discuss the topline results. To join the webcast, please visit the Events page of the Investors & Media section on Intellia's website at intelliatx.com. A replay of the webcast will be available for approximately 90 days.

About Lonvo-z

Based on Nobel Prize-winning CRISPR/Cas9 technology, lonvo-z has the potential to become the first one-time treatment for hereditary angioedema (HAE). Lonvo-z is an in vivo CRISPR gene editing candidate that is intended to permanently lower kallikrein by inactivating the kallikrein B1 (KLKB1) gene with a single dose. Lonvo-z has received five notable regulatory designations: Orphan Drug and RMAT Designation by the U.S. Food and Drug Administration (FDA), the Innovation Passport by the U.K. Medicines and Healthcare products Regulatory Agency (MHRA), Priority Medicines (PRIME) Designation by the European Medicines Agency, as well as Orphan Drug Designation (ODD) by the European Commission.

About Hereditary Angioedema

Hereditary angioedema (HAE) is a rare, genetic disease characterized by severe, recurring and unpredictable inflammatory attacks in various organs and tissues of the body, which can be painful, debilitating and life-threatening. It is estimated that one in 50,000 people are affected by HAE. There are preventative and on-demand treatment options to help manage the condition, including long- and short-term prophylaxis used to prevent swelling attacks. Current treatment options often include lifelong therapies, which may require chronic intravenous (IV) or subcutaneous (SC) administration as often as twice per week or daily oral administration to ensure constant pathway suppression for disease control. Despite chronic administration, breakthrough attacks still occur. Kallikrein inhibition is a clinically validated strategy for the preventive treatment of HAE attacks.

About Intellia Therapeutics

Intellia Therapeutics, Inc. (Nasdaq: NTLA) is a leading clinical-stage biopharmaceutical company focused on revolutionizing medicine leveraging CRISPR gene editing and other core technologies. The company's mission is to transform the lives of people with severe diseases by developing and commercializing potentially curative treatments. With deep scientific, technical and clinical development experience, Intellia aims to reset the standard for medicine by durably treating the root causes of disease. Learn more at intelliatx.com and follow us @intelliatx.