Newron Pharmaceuticals said the U.S. Food and Drug Administration (FDA) has identified four deaths among patients treated with its experimental schizophrenia drug evenamide in feedback provided after the agency’s earlier decision to place a clinical hold on the treatment’s U.S. trial.
According to the company, the FDA noted four deaths among patients who received evenamide across all studies, compared with one death among patients who received a placebo. The agency characterized the four deaths as a potential safety signal because a fatal arrhythmic mechanism could not be definitively excluded.
The FDA also raised concerns related to evenamide’s action as a selective voltage-gated sodium channel blocker. Newron said certain sodium channel blockers may cause irregular heart rhythms that can lead to serious cardiovascular events or seizures.
Clinical Hold Remains in Place
The FDA feedback follows the agency’s earlier decision to halt enrollment of new patients in the Phase 3 ENIGMA-TRS 2 study in the United States after a patient’s sudden death at a trial site outside the U.S.
Newron previously said the death was unrelated to evenamide. The clinical hold remains in place, while enrollment in the study continues outside the United States.
The company said no U.S. patients in ENIGMA-TRS 2 have received evenamide.
Evenamide is being studied in patients with treatment-resistant schizophrenia, a mental illness that affects thinking, emotions, and perception of reality.
Details of the Deaths
Newron reported that four deaths have occurred among patients receiving evenamide across all clinical studies conducted to date, representing an incidence of 0.56%. One death occurred among patients receiving placebo, representing an incidence of 0.27%.
Investigators determined that three of the four deaths among patients receiving evenamide were unrelated to treatment. One death was considered possibly related because two autopsies did not identify a definitive cause of death.
The company said the FDA regarded the four deaths as a potential safety signal because a fatal arrhythmic mechanism could not be conclusively ruled out.
Review of Safety Information
Newron said it is reviewing the FDA’s feedback and safety information collected across the evenamide development program. The company is also evaluating additional cardiac screening and monitoring measures.
According to Newron, it has not identified a pattern of cardiac abnormalities or arrhythmias in its preclinical and clinical safety data. The safety information reviewed includes more than 10,000 ECGs from approximately 700 patients treated with evenamide and more than 5,000 ECGs from over 700 patients with schizophrenia.
The company said it intends to submit a response after completing its review of the FDA’s feedback and available data.
Ongoing Phase 3 Program
The evenamide development program includes the Phase 3 ENIGMA-TRS 1 and ENIGMA-TRS 2 studies. ENIGMA-TRS 1 is a 52-week international study expected to enroll at least 600 patients across 20 countries. ENIGMA-TRS 2 is a 12-week study taking place in the United States and other selected countries.
Commenting on the program, Chief Medical Officer Ravi Anand said, “We remain confident in the ENIGMA-TRS studies and encouraged by the program’s progress.”
Shares of the Switzerland-listed company fell 5.7% in afternoon trading following the FDA’s safety-related feedback.
Newron Pharmaceuticals is facing renewed regulatory scrutiny after the U.S. Food and Drug Administration (FDA) identified four deaths among patients who received its investigational schizophrenia treatment, evenamide. The update, announced on October 8, 2026, follows an earlier FDA decision to suspend new patient enrollment at U.S. sites in the company’s Phase 3 ENIGMA-TRS 2 clinical trial.
Newron confirmed that it has received written feedback from the FDA and is reviewing the agency’s concerns alongside available safety data. The U.S. clinical hold remains in place while the company prepares its response. Enrollment in the study continues outside the United States.
The development raises important questions about the safety assessment of experimental medicines and the evidence required before late-stage clinical trials can proceed without restrictions.
Four Deaths Identified Across Newron Clinical Studies
According to Newron, the FDA identified four deaths among patients treated with evenamide across its clinical studies, compared with one death among patients who received a placebo.
