Intellia Therapeutics Announces Positive Long-Term Data from Ongoing Phase 1 Study of NTLA-2002, an Investigational In Vivo CRISPR Gene Editing Treatment for Hereditary Angioedema (HAE)

• Extended follow-up data reaching over two years in the earliest patients dosed reinforce the potential of NTLA-2002 to be a functional cure for people living with hereditary angioedema (HAE)
• Eight of 10 patients remain completely attack-free following the 16-week primary observation period through the latest follow-up, including patients with the most severe disease
• Single dose of NTLA-2002 led to a 98% mean reduction in monthly HAE attack rate, with an average follow-up of over 20 months across all patients
• 100% of patients who discontinued prophylaxis treatment after NTLA-2002 remain free of chronic prophylaxis treatment
• Favorable safety and tolerability profile observed at all dose levels
• Intellia to host investor webcast on Monday, June 3, at 8 a.m. ET

CAMBRIDGE, Mass., June 02, 2024 – Intellia Therapeutics, Inc. (NASDAQ:NTLA), a leading clinical-stage genome editing company focused on revolutionizing medicine with CRISPR-based therapies, today announced long-term data from the Phase 1 portion of the ongoing Phase 1/2 study of NTLA-2002. NTLA-2002 is an investigational in vivo CRISPR-based gene editing therapy in development as a single-dose treatment for hereditary angioedema (HAE), a rare genetic condition that leads to potentially life-threatening swelling attacks. The data were shared in an oral presentation at the European Academy of Allergy and Clinical Immunology (EAACI) Congress 2024, being held May 31 – June 3 in Valencia, Spain.

“These unprecedented data strengthen our view that NTLA-2002 could be a groundbreaking treatment for people living with hereditary angioedema,” said Intellia President and Chief Executive Officer John Leonard, M.D. “After a single dose of our investigational in vivo CRISPR-based therapy, patients experienced durable elimination of their attacks. We are thrilled to see that the majority of patients have been attack free for over 18 months or longer. These remarkable attack rate reductions have been consistent, even in patients with the most severe symptoms. At the same time, the data from these 10 patients continue to demonstrate a very favorable safety profile. These long-term data provide strong evidence that NTLA-2002 could be a one-time, potential functional cure for this debilitating and life-threatening disease.”

In the Phase 1 portion of the study, single doses of 25 mg (N=3), 50 mg (N=4) and 75 mg (N=3) of NTLA-2002 were administered via intravenous infusion, and HAE attacks and plasma kallikrein protein levels were measured for each patient. The first analysis of HAE attack rates occurred at the end of the pre-specified 16-week primary observation period. HAE attacks and plasma kallikrein protein levels will continue to be assessed through the remainder of the two-year follow-up period.

HAE Attack Rate Reduction¹

¹ Investigator confirmed monthly HAE attack rate % reduction from baseline.
² On-study period is defined as the time from the dosing of NTLA-2002 through the last assessment of HAE attacks as of the data cut-off date of February 12, 2024.

Across all patients, a 98% mean reduction in monthly attack rate and a 99% mean reduction in moderate to severe attacks were observed after a single dose of NTLA-2002 through the latest follow-up. The median duration of follow-up was 20.1 months. At each dose level tested, a robust level of HAE attack rate reduction was achieved and long lasting. The longest attack-free interval for an individual patient post-infusion is over 26 months and ongoing. Additionally, the reduction in HAE attacks has been persistent in patients with the most severe HAE symptoms. The two patients with the highest historic monthly HAE attack rates at the start of the study (16.8 and 14.0 attacks per month, respectively) were attack-free by the end of the 16-week primary observation period and have remained free of attacks through the latest follow-up. The longest attack-free duration amongst these two patients is 23.5 months and ongoing. Further, 100% of patients who discontinued prophylaxis treatment after NTLA-2002 remain free of chronic prophylaxis treatment.

Eight of 10 patients had no attacks following the 16-week primary observation period. These patients have experienced ongoing attack-free durations of greater than 18 months. Of the two patients who had any attacks, one had a mild attack that did not require treatment and a single patient experienced a moderate attack. Amongst these two patients, their mean reduction in monthly HAE attack rate was 97% after a single dose of NTLA-2002 through the latest follow-up.

Plasma Kallikrein Reduction
As previously reported, administration of NTLA-2002 led to dose-dependent, robust and durable reductions in plasma kallikrein. Mean reduction in plasma kallikrein levels from baseline through latest assessment was 60% (25 mg, 88 weeks), 88% (50 mg, 72 weeks), and 95% (75 mg, 88 weeks).

Safety
At all three dose levels, NTLA-2002 was well-tolerated, and the majority of adverse events were mild in severity. Consistent with previously reported results, the most frequent adverse events were infusion-related reactions and fatigue, which were mostly Grade 1 and resolved within two days. There have been no dose-limiting toxicities, no serious adverse events and no adverse events of Grade 3 or higher observed to date. No clinically significant laboratory abnormalities were observed in any patient. Following completion of the
Phase 1 study, patients dosed with NTLA-2002 may be enrolled in a follow-up study to monitor long-term safety and efficacy of the drug.

NTLA-2002 Clinical Development Plans
As previously announced, Intellia completed enrollment of the randomized, placebo-controlled Phase 2 study further evaluating the 25 mg and 50 mg doses and plans to report topline results mid-year with detailed results expected to be presented at a medical meeting later in the year. The Company expects to begin a pivotal, Phase 3 trial of NTLA-2002 in the second half of 2024, subject to regulatory feedback.

Intellia Therapeutics Investor Webcast Information
Intellia will host a live webcast, Monday, June 3, 2024, at 8:00 a.m. ET to discuss the data presented at EAACI. Joining the Intellia management team will be Hilary Longhurst, M.D., Ph.D., FRCP, FRCPath, Senior Medical Officer at Auckland District Health Board and Honorary Associate Professor at University of Auckland, New Zealand, the trial’s principal investigator in New Zealand, to review the new data.

To join the webcast, please visit this link, or the Events and Presentations page of the Investors & Media section of the company’s website at www.intelliatx.com. A replay of the webcast will be available on Intellia’s website for at least 30 days following the call.