GENEVA, Switzerland — October 8, 2026
Addex Therapeutics announced that its spin-out company, Neurosterix, has completed Phase 1 clinical studies of NTX-253, an investigational oral therapy being developed for schizophrenia. Neurosterix plans to advance the candidate into Phase 2 clinical development in patients with the psychiatric disorder. Addex retains a 20% equity interest in Neurosterix, giving it continued exposure to the program’s development progress. Completion of Phase 1 marks an important milestone for the candidate, providing initial clinical safety and pharmacokinetic information to support planning for the next stage of evaluation.
Clinical Studies Assessed Safety and Pharmacokinetics
The Phase 1 program used a multipart, ascending-dose design to characterize NTX-253 and inform subsequent clinical development. It included single ascending dose (SAD) and multiple ascending dose (MAD) components, with studies involving healthy volunteers and stable patients with schizophrenia. Additional assessments included a food-effect evaluation and measurement of drug exposure in cerebrospinal fluid (CSF), supporting the investigation of the candidate’s pharmacokinetic properties and central nervous system exposure. Addex said the studies generated important safety and pharmacokinetic data. Detailed clinical results, including specific adverse events, dose levels and pharmacokinetic measurements, were not disclosed in the announcement.
NTX-253 Targets the Muscarinic M4 Receptor
NTX-253 is an investigational positive allosteric modulator (PAM) of the muscarinic M4 receptor, a target involved in regulating neurotransmitter signaling associated with schizophrenia. Rather than directly blocking dopamine receptors, the compound is designed to enhance the receptor’s response to its natural signaling molecule. This mechanism may offer a different approach to managing psychosis symptoms compared with conventional dopamine-antagonist treatments, which can be associated with movement-related and metabolic adverse effects. Neurosterix describes NTX-253 as a potent, selective oral M4 PAM, with preclinical studies showing antipsychotic-like activity. However, its potential clinical benefits and safety in patients must be established through further controlled studies.
Advertisement
Neurosterix Advances Its Neurology Pipeline
Neurosterix was spun out of Addex in April 2024 following a $65 million Series A financing led by funds affiliated with Perceptive Advisors. Addex’s retained 20% equity interest links the Swiss-listed company to the spin-out’s progress as it advances its portfolio of allosteric modulators for neurological and psychiatric conditions. In addition to NTX-253 for schizophrenia, Neurosterix is developing programs targeting other neuropsychiatric disorders, including an mGlu7 negative allosteric modulator for mood disorders. Addex continues to pursue its own pipeline, including dipraglurant, an mGlu5 negative allosteric modulator, and programs targeting GABA-B receptors. The planned Phase 2 transition for NTX-253 represents the next development step, although no specific trial start date or detailed Phase 2 design was provided.
Source::Addex Therapeutics, press release
