A Brain Imaging Study to Assess the Binding of MSP-2020 to Serotonin 5-HT2A Receptors in Healthy Male Adults

A Phase 1, Open-label, Positron Emission Tomography (PET) Trial to Measure Serotonin 5-HT2A Receptor Occupancy Following Single Oral Doses of MSP-2020 in Healthy Male Adults

This study is to see how well MSP-2020 attaches to specific targets in the brain called serotonin type 2A receptors (5-HT2AR). This study will also look at how much of the study drug (and its metabolite) is in the blood and how long the study drug stays in the blood, as well as the safety of MSP 2020.

Study Overview

• Status: Recruiting
• Conditions: Incomplete Response - Major Depressive Disorder (IR-MDD)
• Intervention / Treatment: Drug: MSP-2020

• Study Type: Interventional
• Enrollment (Estimated): 18
• Phase: Phase 1

Contacts and Locations

• Study Contact: Name: Otsuka Call Center; Phone Number: 844-687-8522; Email: Otsuka-ProfessionalServices@otsuka-us.com

Study Locations

• United Kingdom
  • London, United Kingdom
    • Recruiting
    • HMR Hammersmith Medicines Research Ltd.

Participation Criteria

Eligibility Criteria

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

Description

Inclusion Criteria

1. Able to stay in the CRU for up to 4 days.
2. Body mass index (BMI) between 18.0 to 32.0 kg/m2 (inclusive).
3. In good health as determined by: a. Medical history; b. Physical and neurological examination; c. Concomitant medications; d. ECG; e. Screening echocardiogram; f. Serum chemistry, urinalysis, haematology, coagulation, and serology (HIV screen, HBsAg, and anti-HCV) tests.

Exclusion Criteria

1. In first-degree relatives, a history of any schizophrenia-spectrum disorder, psychotic disorder, or bipolar and related disorders.
2. History of allergy to tracer [11C]CIMBI-36.
3. MRI incompatibility due to implants including but not limited to pacemaker, artificial joints, or non-removable body piercings, and/or other contraindications for MRI such as claustrophobia, metal objects/fragments, or fragments in the head or body that would present a risk during the MRI scanning procedure, or have worked with ferrous metals (eg, welding), or have motor problems that prevent the participant from lying still for the MRI.
4. Pathological MRI findings that would preclude from trial participation.
5. History of prior radiation exposure for research purposes such that participation in this trial would result in an ionising radiation exposure of > 10 mSv within a year (12 months) of the first PET scan that would cause the participant to exceed the yearly dose limit.
6. Have a negative modified Allen test at screening.
7. Contraindications to radial arterial cannula (including but not limited to cellulitis or other infections over the radial artery, absence of palpable radial artery pulse, or a clinically significant abnormal coagulation profile).
8. Clinically significant abnormality in past medical history, or at the screening physical examination, that in the investigator's or sponsor's opinion may place the participant at risk or interfere with outcome variables including absorption, distribution, metabolism, and excretion of drug. This includes, but is not limited to, history of or concurrent cardiac, hepatic, renal, neurologic, endocrine, gastrointestinal, respiratory, haematologic, dermatologic, and immunologic disease.
9. History of alcohol and/or substance use disorder within the last 24 months according to the Diagnostic Statistical Manual of Mental Disorders and in past medical history or in the investigator's opinion, or intake of > 21 units of alcohol weekly, and the inability to refrain from alcohol use from 48 hours before screening and within 72 hours prior to dosing until discharge from the CRU on Day 2. One unit is equivalent to 1 (25 mL) measure of 40% spirits. For reference, one 330 mL bottle of 5% beer contains 1.7 units and a standard (175 mL) glass of 12% wine contains 2.1 units.

Note: Other protocol-specified Inclusion/Exclusion criteria may apply.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Sequential Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: MSP-2020 Oral Administration; Participants will receive a single dose of MSP-2020 on Day 1.	Drug: MSP-2020; capsule

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Percent Change in Specific Binding of [11C]CIMBI-36 from Baseline and EC50 Using Cortical Regions [11C]CIMBI-36 BPND	Up to Day 2
PK Plasma Concentration of MSP-2020 and its Metabolite	Up to Day 2
Maximum (peak) Plasma Concentration of MSP-2020 and its Metabolite	Up to Day 2
Time to Maximum (peak) Plasma Concentration of MSP-2020 and its Metabolite	Up to Day 2
Half-life (t1/2) of MSP-2020 and its metabolite	Up to Day 2
Area under the concentration-time curve (AUCt) of MSP-2020 and its metabolite	Up to Day 2

Secondary Outcome Measures

Outcome Measure	Time Frame
Concentration of the metabolite at which 50% of the 5-HT2A receptors are occupied, as measured by PET imaging	Up to Day 2
Number of Participants With Adverse Events (AEs)	Up to Day 15
Number of Participants With Potentially Clinically Significant Changes in Vital Signs	Up to Day 2
Number of Participants With Potentially Clinically Significant Changes in Electrocardiogram (ECG)	Up to Day 2
Number of Participants With Potentially Clinically Significant Changes in Laboratory Tests	Up to Day 15
Number of Participants With Potentially Clinically Significant Changes in Physical and Neurological Examinations	Up to Day 15
Number of Participants With Suicidality on Columbia-Suicide Severity Rating Scale (C-SSRS)	Up to Day 15
Change from baseline in relevant scales	Up to Day 2

Collaborators and Investigators

• Sponsor: Otsuka Pharmaceutical Development & Commercialization, Inc.

Study record dates

Study Major Dates

• Study Start (Actual): January 15, 2026
• Primary Completion (Estimated): January 29, 2027
• Study Completion (Estimated): February 11, 2027

Study Registration Dates

• First Submitted: December 19, 2025
• First Submitted That Met QC Criteria: January 6, 2026
• First Posted (Actual): January 9, 2026

Study Record Updates

• Last Update Posted (Actual): February 27, 2026
• Last Update Submitted That Met QC Criteria: February 25, 2026
• Last Verified: February 1, 2026

More Information

Terms related to this study

• Other Study ID Numbers: 358-201-00002

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Anonymized individual participant data (IPD) that underlie the results of this study will be shared with researchers to achieve aims pre-specified in a methodologically sound research proposal. Small studies with less than 25 participants are excluded from data sharing.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No