Single and Multiple Ascending Doses of NTX-253 in Healthy Participants and Participants With Stable Schizophrenia

A First in Human, Phase 1/1b Study of Single and Multiple Ascending Dosing Administration of NTX110253 in Healthy Participants and Participants With Stable Schizophrenia

This study will assess the safety, tolerability, and pharmacokinetics of NTX-253 following oral administration in both healthy adult participants as well as adult participants with stable schizophrenia.

Study Overview

• Status: Recruiting
• Conditions: Healthy Participants; Schizophrenia Diagnosis
• Intervention / Treatment: Drug: Placebo; Drug: NTX-253

Detailed Description

This study will assess the safety, tolerability, and pharmacokinetics of NTX-253 following oral administration in both healthy adult participants as well as adult participants with stable schizophrenia. NTX-253 is an investigational drug being developed for the treatment of schizophrenia. The study will consist of a single ascending dose (SAD - Part 1a) phase which will include a food effect cohort, and a cerebrospinal fluid (CSF - Part 1b) cohort in healthy volunteers. Participants will receive a single dose of either oral NTX-253 or placebo. The multiple ascending dose (MAD - Part 2) phase will follow. In Part 2, participants will be dosed for 10 consecutive days with either NTX-253 or placebo. Each phase will include sequential escalating doses in healthy volunteers. Two cohorts in the MAD phase will include stable schizophrenic adult participants who have had antipsychotic medication withdrawn for up to 8 days prior to dosing with NTX-253.

• Study Type: Interventional
• Enrollment (Estimated): 73
• Phase: Early Phase 1

Contacts and Locations

• Study Contact: Name: Doug Feltner, Chief Medical Officer, MD; Phone Number: +41 22 884 15 55; Email: doug.feltner@neurosterix.com
• Study Contact Backup: Name: Lisa Corey; Phone Number: +41 22 884 15 55; Email: lisa.corey@neurosterix.com

Study Locations

• United States
  • California
    • Los Alamitos, California, United States, 90720
      • Recruiting
      • Collaborative Neuroscience Research, LLC - CenExel
      • Contact: Recruitment; Phone Number: 866-787-4257; Email: alamitors.info@CenExel.com

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Primary Inclusion Criteria:

• Male or non-pregnant, non-lactating female participants, ages 18-55 who are not of childbearing potential, with a truly abstinent lifestyle, or agrees to use medically acceptable forms of birth control
• Part 1 a/b, Part 2 Cohort 7 only: Body mass index (BMI) within the range ≥18.0 to ≤30.0 kg/m2
• Participants in the food effect cohort must be willing to eat a single high fat breakfast
• (Part 2 only): Stable schizophrenia participants (schizophrenia cohorts only)
• Body mass index (BMI) within the range ≥17.5 to ≤36.0 kg/m2
• Positive and Negative Syndrome Scale (PANSS) total score <80 at screening

Primary Exclusion Criteria:

• (Part 1a/b, Part 2 Healthy): History of or current clinically significant medical or mental illness
• Cancer diagnosis/treatment in the past 7 years
• Acute or chronic gastrointestinal conditions that would interfere with drug tolerance or absorption
• Any clinically significant, abnormal 12 lead ECG
• Part 2: Any primary DSM-5TR disorder other than schizophrenia
• Participants with schizophrenia who are considered resistant/refractory to antipsychotic treatment by history; history of clozapine use.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Double

Number of Arms

5

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: NTX-253 Part 1a; Participants will be assigned to receive one of multiple single ascending daily oral doses of NTX-253	Drug: NTX-253; Oral Capsule
Experimental: Placebo Part 1a; Participants will be assigned to receive one of multiple single ascending daily oral doses of placebo	Drug: Placebo; Oral capsule
Experimental: NTX-253 Part 1b; Participants will receive the maximum tolerated single oral dose of NTX-253	Drug: NTX-253; Oral Capsule
Experimental: NTX-253 Part 2; Participants will be assigned to receive one of multiple ascending oral daily doses of NTX-253 for 10 days	Drug: NTX-253; Oral Capsule
Experimental: Placebo Part 2; Participants will be assigned to receive one of multiple ascending daily oral doses of placebo for 10 days	Drug: Placebo; Oral capsule

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Number of reported Adverse Events	Safety and tolerability will be assessed by the incidence and severity of treatment-emergent adverse events.	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Number of Adverse Events of Special Interest (AESI)	Safety and tolerability will be assessed by the incidence and severity of AESIs.	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Number of dose limiting treatment emergent adverse events (TEAE)	Safety and tolerability will be assessed by the incidence and severity of serious or dose limiting TEAEs.	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Vital Signs: Change in blood pressure	Blood pressure measurements	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Vital Signs: Change in temperature	Oral temperature measurement	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Vital Signs: Change in respiratory rate	Respiratory rate (number of breaths per minute) measurements	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Vital Signs: Change in heart rate	Pulse measurements.	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Change in physical examination	Investigator will perform complete physical exam and document any clinically significant conditions.	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).
Clinical Laboratory Tests	Hematology, serum chemistry, urinalysis, and coagulation tests.	From baseline until Day 8 after a single dose, Day 17 (healthy volunteers) or Day 35 (participants with stable schizophrenia).

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Maximum observed plasma concentration (Cmax) [Pharmacokinetics]	Samples will be collected periodically until: 72 hours after a single dose with optional samples collected at 96, 120, 144, and 168 post-dose.; 72 hours after multiple doses with optional samples collected at 96, 120, 144, and 168 hours after the last dose.	From baseline until up to 168 hours after a single dose, or until up to 168 hours after the last dose in the multiple dose cohorts.
Time of Cmax (tmax) [Pharmacokinetics]	Samples will be collected periodically until: 72 hours after a single dose with optional samples collected at 96, 120, 144, and 168 post-dose.; 72 hours after multiple doses with optional samples collected at 96, 120, 144, and 168 hours after the last dose.	From baseline until up to 168 hours after a single dose, or until up to 168 hours after the last dose in the multiple dose cohorts.
Apparent terminal half-life (t1/2)	Samples will be collected periodically until: 72 hours after a single dose with optional samples collected at 96, 120, 144, and 168 post-dose.; 72 hours after multiple doses with optional samples collected at 96, 120, 144, and 168 hours after the last dose.	From baseline until up to 168 hours after a single dose, or until up to 168 hours after the last dose in the multiple dose cohorts.
Amount of unchanged drug excreted in urine (Ae) [urinary excretion)	Samples will be collected in select cohorts from baseline until 72 hours after a single dose, or at baseline and on the last dosing day after multiple dose administrations.	From baseline until 72 hours after a single dose, or until the last dosing on Day 10 in the multiple dose cohort.
Percent of dose excreted as unchanged drug in urine (Ae%) [urinary excretion]	Samples will be collected in select cohorts from baseline until 72 hours after a single dose, or at baseline and on the last dosing day after multiple dose administrations.	From baseline until 72 hours after a single dose, or until the last dosing on Day 10 in the multiple dose cohort.
Renal clearance (Clr) [urinary excretion]	Samples will be collected in select cohorts from baseline until 72 hours after a single dose, or at baseline and on the last dosing day after multiple dose administrations.	From baseline until 72 hours after a single dose, or until the last dosing on Day 10 in the multiple dose cohort.
Maximum observed CSF concentration (Cmax, CSF) [Pharmacokinetics]	CSF samples will be collected at periodic intervals until 12 hours after a single dose in a single dose CSF cohort.	From baseline until 12 hours after a single dose.
Time corresponding to Cmax (Tmax, CSF) [Pharmacokinetics]	CSF samples will be collected at periodic intervals until 12 hours after a single dose in a single dose CSF cohort.	From baseline until 12 hours after a single dose.
QT/QTc potential interval prolongation and plasma concentration	Electrocardiograms (ECGs) will be collected to assess the potential for QT/QTc interval prolongation and ΔQTc as measured by: • Change from baseline in cardiac measurements	From baseline until 72 hours post-dose in the single dose cohorts, then from baseline until Day 13 in the multiple dose cohorts.

Collaborators and Investigators

• Sponsor: Neurosterix
• Investigators: Study Director: Doug Feltner, MD, Neurosterix

Study record dates

Study Major Dates

• Study Start (Actual): October 3, 2025
• Primary Completion (Estimated): May 1, 2026
• Study Completion (Estimated): May 1, 2026

Study Registration Dates

• First Submitted: November 14, 2025
• First Submitted That Met QC Criteria: January 7, 2026
• First Posted (Actual): January 15, 2026

Study Record Updates

• Last Update Posted (Actual): January 15, 2026
• Last Update Submitted That Met QC Criteria: January 7, 2026
• Last Verified: January 1, 2026

More Information

Terms related to this study

• Keywords: Safety; Schizophrenia; Pharmacokinetics; Food effect; Phase 1; Multiple ascending dose; Healthy volunteer; Single ascending dose
• Additional Relevant MeSH Terms: Schizophrenia Spectrum and Other Psychotic Disorders; Mental Disorders; Schizophrenia
• Other Study ID Numbers: NTX-0253-101

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: Yes
• Studies a U.S. FDA-regulated device product: No