Intellia pauses gene therapy trials after patient suffers liver injury, shares slide

By Padmanabhan Ananthan

Oct 27 (Reuters) - Intellia Therapeutics NTLA.O has temporarily stopped dosing and patient screening in two late-stage studies of its gene therapy after a participant developed serious liver injury, the company said on Monday, sending its shares down over 46% in morning trading.

The patient, who received Nexiguran ziclumeran (nex-z), showed sharp spikes in liver enzymes and elevated bilirubin, triggering a protocol-defined safety pause, the company said. The individual has been hospitalized and is under medical care.

Nex-z is being studied as a potential one-time treatment for transthyretin amyloidosis with cardiomyopathy (ATTR-CM), a rare and deadly heart disease in which faulty transthyretin proteins accumulate in the heart and can cause the organ to fail.

The development marks a setback for the company, which is developing treatments based on the CRISPR technology. Nex-z works by turning off the gene responsible for producing the transthyretin protein.

"Looking ahead, we continue to anticipate that safety concerns surrounding Intellia's programs will represent a mounting headwind for their pipeline, given the availability of alternative treatments that produce a similar clinical effect, and that this dynamic will stunt investor enthusiasm for this story," Baird analyst Jack Allen said.

Intellia said it is consulting outside experts, weighing risk‑reduction steps and speaking with regulators about a plan to restart enrollment "as soon as appropriate."

"We are actively engaging with the agency... we have not heard that a (clinical) hold is in the works," said CEO John Leonard on a conference call.

"Despite this recent event, we continue to believe in nex-z's potential to address important unmet needs for patients with ATTR amyloidosis", he added, saying that the company will share long-term data from an early-stage trial in early November.

The current treatment landscape for ATTR-CM includes Alnylam Pharmaceuticals' ALNY.O injectable drug Amvuttra, Pfizer's PFE.N blockbuster Vyndaqel and BridgeBio Pharma's BBIO.O Attruby.