FDA Fully Lifts Clinical Hold on Intellia Therapeutics' CRISPR Gene Therapy Trials for ATTR Amyloidosis
The FDA fully lifted the clinical hold on Intellia's Magnitude phase 3 trial of nexiguran ziclumeran (nex-z) for transthyretin amyloidosis with cardiomyopathy (ATTR-CM) on March 2, 2026.
The hold was imposed in October 2025 after a patient in the Magnitude trial experienced serious liver toxicity (elevated liver enzymes) leading to death.
The hold on the related Magnitude-2 trial for hereditary transthyretin amyloidosis with polyneuropathy (ATTRv-PN) was lifted earlier in January 2026.
New safety measures include excluding patients with certain liver issues, heart ejection fraction <25%, or recent cardiovascular instability; enhanced liver enzyme monitoring; and guidance on short-term steroid treatments.
Nex-z is a one-time CRISPR/Cas9-based therapy, partnered with Regeneron, designed to inactivate the TTR gene to treat ATTR conditions.
Analysts view the safety adjustments as modest with minimal timeline disruption, but note uncertainty around the liver toxicity cause may affect adoption.