By Kelly Cloonan

Shares of Intellia Therapeutics fell after the company reported a grade 4 adverse event in a study of nex-z, its treatment for hereditary ATTR amyloidosis with polyneuropathy.

The stock was down 24% to $7.32 on Thursday. Shares have declined 66% in the past 12 months.

An asymptomatic patient in the Phase 3 study who was dosed with the treatment had grade 4 liver transaminase elevations, based on laboratory tests, according to a filing with the Securities and Exchange Commission on Wednesday.

The effects appear to be resolving without hospitalization or medical intervention, the company said.

The development reinforces concerns around the potential for commercial uptake for nex-z, Wedbush Securities analysts said in a note. While other treatments, such as emerging therapies like Alnylam Pharmaceuticals' twice-yearly nucresiran, can be discontinued, changes from nex-z are potentially life-long, the analysts said.

Analysts at Oppenheimer said in a note they are not overly concerned by the safety findings. There are no signs of liver injury and similar transient liver enzyme elevations previously occurred around a similar timeline in the company's Phase 1 trial, they said.

In the over 200 patients dosed with nex-z in the study so far, adverse events are similar to those reported in the drug's Phase 1 study, the company said. That includes infusion-related reactions and asymptomatic liver transaminase elevations.

The study has enrolled approximately 365 out of an expected 765 patients so far, with enrollment expected to be complete by early 2027, the company said.

Write to Kelly Cloonan at kelly.cloonan@wsj.com

(END) Dow Jones Newswires

May 29, 2025 11:55 ET (15:55 GMT)

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