Serious adverse events occurred in the phase III clinical trial of Nex-Z. Intellia's (NTLA.US) stock price plummeted over 40%.

Intellia Therapeutics (NTLA.US) saw its stock price plummet by 47.6% at one point in Monday's trading session, closing down 42.23%, after halting dosing in two Phase III clinical trials for nexiguran ziclumeran (referred to as nex-z). The dosing halt was prompted by a serious adverse event reported in the MAGNITUDE trial: a patient was hospitalized due to Grade 4 elevation of liver transaminases and total bilirubin. The trial was evaluating the efficacy and safety of nex-z in treating transthyretin amyloid cardiomyopathy (ATTR-CM). Another trial that was paused is MAGNITUDE-2, focusing on transthyretin amyloid polyneuropathy (ATTR-PN). Patient enrollment for both trials has been suspended. As of now, the MAGNITUDE trial has enrolled 650 patients, while the MAGNITUDE-2 trial has enrolled 47 patients. It is estimated that over 450 patients have received nex-z dosing as part of the treatment.