Intellia Therapeutics, Inc. and Regeneron Pharmaceuticals, Inc. announced positive interim results from an ongoing Phase 1 clinical trial of NTLA-2001, an investigational, in vivo CRISPR/Cas9 genome editing therapy in development as a single-dose treatment for transthyretin (ATTR) amyloidosis. The interim data include 12 adult patients with ATTR amyloidosis with cardiomyopathy (ATTR-CM) with New York Heart Association (NYHA) Class I – III heart failure. Single doses of 0.7 mg/kg and 1.0 mg/kg of NTLA-2001 were administered via intravenous infusion, and the change from baseline in serum transthyretin (TTR) protein concentration was measured for each patient.

These profound reductions in serum TTR were sustained throughout the observation period, with patient follow-up ranging from two to six months as of the data cut-off date of July 1, 2022. These data support NTLA-2001's potential as a one-time treatment to permanently inactivate the TTR gene and reduce the disease-causing protein in people with ATTR-CM. At both dose levels, NTLA-2001 was generally well tolerated.

Two of 12 patients reported transient infusion reactions, which was the only observed treatment-related adverse event. One patient in the 0.7 mg/kg dose NYHA Class III cohort experienced a Grade 3 infusion-related reaction, which resolved without clinical consequence. Per the study protocol, this group was subsequently expanded from three to six patients to further characterize safety at this dose level.

No additional patients in the 0.7 mg/kg dose NYHA Class III cohort reported a treatment-related adverse event. No clinically significant liver findings were observed at either dose level. The Phase 1 study, run by Intellia as the program's development and commercialization lead as part of a multi-target collaboration with Regeneron, is evaluating NTLA-2001 in patients with either ATTR-CM or hereditary ATTR amyloidosis with polyneuropathy (ATTRv-PN).

A protocol amendment has been submitted to evaluate a fixed dose corresponding to 0.7 mg/kg in the dose-expansion portion, with enrollment across both arms expected to be completed by the end of 2022, subject to regulatory feedback. Based on Nobel Prize-winning CRISPR/Cas9 technology, NTLA-2001 could potentially be the first single-dose treatment for ATTR amyloidosis. NTLA-2001 is the first investigational CRISPR therapy candidate to be administered systemically, or through a vein, to edit genes inside the human body.

Intellia's proprietary non-viral platform deploys lipid nanoparticles to deliver to the liver a two-part genome editing system: guide RNA specific to the disease-causing gene and messenger RNA that encodes the Cas9 enzyme, which carries out the precision editing. Robust preclinical data, showing deep and long-lasting transthyretin (TTR) reduction following in vivo inactivation of the target gene, supports NTLA-2001's potential as a single-administration therapeutic. Intellia leads development and commercialization of NTLA-2001 as part of a multi-target discovery, development and commercialization collaboration with Regeneron.

The global Phase 1 trial is an open-label, multi-center, two-part study of NTLA-2001 in adults with hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) or transthyretin amyloidosis with cardiomyopathy (ATTR-CM). Transthyretin amyloidosis, or ATTR amyloidosis, is a rare, progressive and fatal disease. Hereditary ATTR (ATTRv) amyloidosis occurs when a person is born with mutations in the TTR gene, which causes the liver to produce structurally abnormal transthyretin (TTR) protein with a propensity to misfold.

These damaged proteins build up as amyloid in the body, causing serious complications in multiple tissues, including the heart, nerves and digestive system. ATTRv amyloidosis predominantly manifests as polyneuropathy (ATTRv-PN), which can lead to nerve damage, or cardiomyopathy (ATTRv-CM), which can lead to heart failure. Some individuals without the genetic mutation produce non-mutated, or wild-type TTR proteins that become unstable over time, misfolding and aggregating in disease-causing amyloid deposits.

This condition, called wild-type ATTR (ATTRwt) amyloidosis, primarily affects the heart. There are an estimated 50,000 people worldwide living with ATTRv amyloidosis and between 200,000 and 500,000 people with ATTRwt amyloidosis.