An Exploratory Analysis of Immune and Inflammatory Response Associated With Clozapine

February 23, 2026 updated by: Walter Stearns, Ohio State University

An Exploratory Analysis of Immune and Inflammatory Response Associated With Clozapine Versus Non-Clozapine Antipsychotics in Individuals With Treatment-resistant Schizophrenia

The specific aim of this protocol is to compare Clozapine treatment vs Non-Clozapine antipsychotic treatment in a population of treatment-refractory individuals with schizophrenia. Specifically, it is to test if Clozapine leads to a decrease in levels of inflammatory markers, namely interleukin-6 but with an exploratory view of other markers. Clozapine has superior efficacy and is the only medication approved for treatment-refractory schizophrenia in addition to decreasing the risk of suicidal behavior as well. It is unclear why Clozapine has increased efficacy from a mechanistic viewpoint. We will look at the role of inflammatory markers and assess them 1x along with rating scales for psychosis and suicidality, the other entities which Clozapine has been shown to improve.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Terminated

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

This study is designed to investigate if treatment with the antipsychotic Clozapine is associated with changes in various immune and inflammatory biomarkers when compared to treatment with non-Clozapine antipsychotic treatments. Clozapine is a uniquely efficacious treatment of psychotic disorders, the only effective agent in approximately 30-40% of individuals with treatment refractory symptoms. Clozapine, unlike other antipsychotic drugs, often precipitates a unique, multi-systemic inflammatory response most widely recognized in the cardiovascular system but also likely the central nervous system (CNS) which is tied into its unique side effect profile but might also account for its increased efficacy. Schizophrenia spectrum disorders affect about 1% of the population with around 30-40% of those diagnosed with symptoms refractory to standard, non-Clozapine antipsychotic treatment. We will measure various inflammatory markers 1x for patients who are stable outpatients. Participants will be patients with treatment-resistant schizophrenia on clozapine treatment for at least 6 months referred from OSU's outpatient clinic with a comparator group also referred from Ohio State University, having shown treatment resistant symptoms but with provider/patient electing not to use clozapine for clinically relevant reasons and have been on antipsychotic medication for at least 6 months. The study includes 1 visit including symptom rating scale assessments and laboratory draw for collection of serum samples and the visit also having more diagnostic assessments to assure proper enrollment. If the study results are positive meaning there is a difference between the two groups, it would help elucidate the potential mechanisms by which Clozapine works and demonstrates increased efficacy for those with treatment-refractory schizophrenia, a severely debilitating, life long illness with marked disability. This would also allow for further studies to explore this mechanism and the role of inflammation and the immune system as well.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Actual)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
5

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Contact Backup

Study Locations

  • United States
    • Ohio
      • Columbus, Ohio, United States, 43210
        • Ohio State University Harding Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

18 years to 40 years (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • All participants:

    • Between 18 and 65 years of age
    • Physically healthy (no clinically significant unstable medical condition as confirmed by medical history and physical examination)
    • Able to give informed consent
    • Treatment-Refractory Schizophrenia

Clozapine treatment group (n = 30) Individuals treated with Clozapine consistently for a minimum of 6 months

Non-Clozapine treatment group Continued treatment with non-Clozapine antipsychotic but would be eligible for Clozapine with the provider/patient electing to not pursue such for clinical reasons, consistently treated for at least 6 months

Exclusion Criteria:

  • Clinically significant medical condition; cardiovascular, pulmonary, endocrine, or renal condition requiring in depth medical treatment
  • Active or recent (within 4 weeks) bacterial or viral infection
  • Chronic viral infection (hepatitis, HIV)
  • History of autoimmune, or chronic inflammatory condition
  • Current treatment with lithium
  • Treatment with Clozapine in the past 6 months
  • Current treatment with immunomodulatory or anti-inflammatory therapy
  • Vaccination within the past 3 months
  • Current alcohol or substance use disorder of moderate or severe severity
  • Intellectual disability (i.e. intelligence quotient <70)
  • Unwilling or unable to sign informed consent document
  • Pregnancy
  • Any patient deemed ineligible by PI discretion

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Diagnostic
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Experimental: Clozapine Arm
Patients will be on Clozapine for at least 6 months
Drug: Clozapine
We will assess inflammatory/immune marker labs
Active Comparator: Non-Clozapine arm
Patients will be on non-Clozapine antipsychotic for at least 6 months
Drug: Antipsychotics,Other (non-Clozapine)
We will assess monitor inflammatory/immune marker lab
Other Names:
  • Including Olanzapine, Risperidone, Paliperidone, Quetiapine, Aripiprazole, Ziprasidone, Lurasidone, Cariprazine, and all Typical antipsychotics

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Interleukin-6 (IL-6)
Time Frame: Up to 1 year
Comparison in interleukin-6 between Clozapine and non-Clozapine group
Up to 1 year

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Other immune/cardiac markers
Time Frame: Up to 1 year
Comparison in hsCRP, interleukin-1β, interferon-γ, transforming growth factor-β, tumor necrosis factor between Clozapine and non-Clozapine group
Up to 1 year
Positive and Negative Syndrome symptom Scale
Time Frame: Up to 1 year
Comparison in psychosis rating scales (PANSS) between Clozapine and non-Clozapine group. Higher scores indicate more severe symptoms of psychosis. Score from 30-210
Up to 1 year
Self-injurious Thoughts and Behaviors Interviews
Time Frame: Up to 1 year
Comparison between Clozapine and non-Clozapine group in Suicidality rating scales. Scores on rating will be binary (yes/no) for suicidal ideation and also suicide attempts.
Up to 1 year

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
Ohio State University

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
August 16, 2023

Primary Completion (Actual)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
January 23, 2026

Study Completion (Actual)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
January 23, 2026

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
January 20, 2023

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 22, 2023

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
February 23, 2023

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 25, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 23, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2021H0388

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

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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