Addex Spin-Out Neurosterix Begins Phase 1 Trial of Novel Schizophrenia Drug NTX-253

Addex Spin-Out Neurosterix Begins Phase 1 Trial of Novel Schizophrenia Drug NTX-253

By, Admin 9 January 2026

Addex Therapeutics has reached a key clinical milestone in schizophrenia drug development. Its spin-out company, Neurosterix, has initiated a Phase 1 clinical trial of NTX-253, a next-generation oral therapy targeting the muscarinic M4 receptor.

What Is NTX-253?

NTX-253 is a potent, selective, orally available positive allosteric modulator (PAM) of the muscarinic M4 receptor. Unlike traditional antipsychotics, it does not directly block dopamine receptors.

Instead, it:

  • Fine-tunes muscarinic signalling
  • Indirectly modulates dopamine pathways
  • Aims to reduce psychosis with fewer side effects

This represents a novel mechanism in schizophrenia treatment.

Phase 1 Study: What’s Being Evaluated

The Phase 1 study is being conducted in healthy volunteers.

Its primary objectives include:

  • Safety and tolerability
  • Pharmacokinetics (how the drug behaves in the body)
  • Pharmacodynamics (biological effects of the drug)

This is NTX-253’s first-in-human clinical evaluation.

Why Target the M4 Muscarinic Receptor?

The M4 receptor is a validated target in schizophrenia research.

Current antipsychotics:

  • Primarily block dopamine receptors
  • Often cause metabolic, cognitive, and motor side effects

M4 PAMs offer a different path.

Research suggests they can:

  • Reduce psychotic symptoms
  • Avoid movement disorders
  • Minimise metabolic complications

All without peripheral muscarinic side effects seen with direct agonists.

Preclinical Data Supports Clinical Advancement

NTX-253 showed strong promise in preclinical studies.

Key findings included:

  • Robust antipsychotic-like activity
  • Favourable safety profile
  • Reversal of dopamine-driven behaviours in animal models

These results supported progression into human trials.

Strategic Importance for Addex and Neurosterix

Neurosterix was spun out of Addex in April 2024.

Key background details:

  • Raised $65 million in Series A financing
  • Funding led by affiliates of Perceptive Advisors
  • Addex retains a 20% equity stake

According to Addex CEO Tim Dyer, NTX-253 represents a differentiated therapeutic approach with potential safety and efficacy advantages.

How This Fits Into Addex’s Broader Pipeline?

Addex continues to focus on allosteric modulators for neurological disorders.

Its lead program:

  • Dipraglurant, an mGlu5 negative allosteric modulator
  • Being evaluated for brain injury recovery
  • Including post-stroke and traumatic brain injury

The Neurosterix spin-out allows sharper focus on schizophrenia.

The Bigger Picture

Schizophrenia treatment has seen limited mechanistic innovation for decades. NTX-253 signals:

  • A move beyond dopamine-centric drugs
  • Growing interest in muscarinic modulation
  • Renewed momentum in CNS drug innovation

If successful, M4 PAMs could reshape the antipsychotic landscape.

Bottom Line

Neurosterix’s Phase 1 start is more than a routine trial update.

It reflects:

  • Confidence in M4-based schizophrenia therapies
  • Smart portfolio separation by Addex
  • A serious attempt to improve safety and outcomes in psychiatric care

NTX-253 is now officially in the clinic—and worth watching closely.

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