The Overview
Newron Pharmaceuticals announced an update on the FDA clinical hold for its Phase 3 ENIGMA-TRS 2 study of evenamide in the U.S., following written communication from the agency. The FDA's concern relates to the known risk of sodium channel blockers triggering arrhythmias and potential safety signals from four deaths among evenamide-treated patients across all studies, compared to one in placebo. Newron is thoroughly reviewing the feedback and safety data, intending to respond soon. Meanwhile, enrollment for ENIGMA-TRS 1 is expected to complete by mid-October 2026, with topline 12-week data anticipated in Q1 2027, and ENIGMA-TRS 2 enrollment continues outside the U.S.
Knolens Analysis
At a Glance
| Indication | Treatment-resistant schizophrenia |
| Drug | evenamide |
| Mechanism of Action | glutamate modulator, selective voltage-gated sodium channel blocker |
| Company | Newron Pharmaceuticals S.p.A. |
| Trial Phase | Phase 3 |
| Trial Acronym | ENIGMA-TRS |
| Category | Clinical Trial Event |
| Sub Category | Trial Halted / Terminated |
| Therapeutic Area | Neuroscience |
| Regulatory Agency | U.S. Food and Drug Administration (FDA) |
| Study Status | Clinical Hold (U.S. study centers for ENIGMA-TRS 2), Enrollment continuing (ENIGMA-TRS 1, ENIGMA-TRS 2 outside U.S.) |
| Enrollment Completion (ENIGMA-TRS 1) | mid-October 2026 |
| Topline Data Expectation (ENIGMA-TRS 1) | Q1 2027 |
| Number of Deaths (evenamide) | 4 |
| Number of Deaths (placebo) | 1 |
| Mortality Rate (evenamide) | 1.31 per 100 patient-years |
| Mortality Rate (placebo) | 1.81 per 100 patient-years |
| Patient Population (ENIGMA-TRS 1) | at least 600 patients |
| Patient Population (ENIGMA-TRS 2) | at least 400 patients |
| Primary Efficacy Endpoint (ENIGMA-TRS 1) | change from baseline in the Positive and Negative Syndrome Scale (PANSS) scores at 12 weeks |
FDA Clinical Hold Update on Evenamide's ENIGMA-TRS Program
Newron Pharmaceuticals announced an update on the FDA clinical hold for its Phase 3 ENIGMA-TRS 2 study of evenamide in the U.S., following written communication from the agency. The FDA's concern relates to the known risk of sodium channel blockers triggering arrhythmias and potential safety signals from four deaths among evenamide-treated patients across all studies, compared to one in placebo. Newron is thoroughly reviewing the feedback and safety data, intending to respond soon. Meanwhile, enrollment for ENIGMA-TRS 1 is expected to complete by mid-October 2026, with topline 12-week data anticipated in Q1 2027, and ENIGMA-TRS 2 enrollment continues outside the U.S.
- The FDA's clinical hold on the U.S. arm of the ENIGMA-TRS 2 study stems from concerns about the class risk of sodium channel blockers, which evenamide is, potentially causing arrhythmias and serious cardiovascular events or seizures. The agency noted four deaths in evenamide-treated patients versus one in placebo, characterizing this as a potential safety signal due to a possible fatal arrhythmic mechanism that could not be definitively excluded.
- Newron is reviewing extensive safety data, including over 10,000 ECGs from approximately 700 evenamide-treated subjects, and has not observed a pattern of cardiac abnormalities or arrhythmias. The company highlights a lower mortality rate adjusted for treatment duration (1.31 per 100 patient-years for evenamide vs. 1.81 per 100 patient-years for placebo) and plans to evaluate additional cardiac screening and monitoring measures as part of its response to the FDA.
- Despite the U.S. clinical hold on ENIGMA-TRS 2, the overall Phase 3 program is advancing. ENIGMA-TRS 1, an international 52-week study for treatment-resistant schizophrenia, is on track to complete enrollment of at least 600 patients by mid-October 2026, with primary 12-week efficacy data (PANSS scores) expected in Q1 2027. Enrollment for ENIGMA-TRS 2 continues in non-U.S. regions.
Frequently Asked Questions
What is evenamide's proposed mechanism of action in schizophrenia?
Evenamide is a novel investigational agent that acts as a selective modulator of the glutamatergic system. Specifically, it functions as a partial agonist at the glycine site of the N-methyl-D-aspartate (NMDA) receptor. This mechanism aims to restore glutamatergic hypofunction, which is implicated in the pathophysiology of schizophrenia, particularly in cognitive and negative symptoms.
How does evenamide aim to address the unmet needs in treatment-resistant schizophrenia?
Treatment-resistant schizophrenia (TRS) presents significant challenges due to inadequate response to standard antipsychotics. Evenamide targets the glutamatergic system, offering a distinct approach from dopamine D2 receptor antagonism, which is the primary mechanism of most current treatments. This novel mechanism may provide efficacy in patients who have not responded to conventional therapies, potentially improving both positive and negative symptoms.
What are the potential clinical benefits of evenamide for patients with treatment-resistant schizophrenia?
Evenamide's unique mechanism of action suggests potential for broad efficacy across various symptom domains in treatment-resistant schizophrenia. Beyond positive symptoms, it may offer improvements in negative symptoms and cognitive deficits, which are often poorly addressed by existing treatments. Its distinct pharmacological profile could lead to a more favorable tolerability profile compared to some current options.
What considerations are important when evaluating novel agents like evenamide for treatment-resistant schizophrenia?
When evaluating novel agents for treatment-resistant schizophrenia, clinicians and strategists consider several factors beyond efficacy, including safety and tolerability profiles. The potential for drug-drug interactions, impact on metabolic parameters, and the overall burden of treatment are crucial. Understanding how a new agent integrates into existing treatment algorithms and its potential to improve long-term functional outcomes is also paramount.
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