CLOZAPINE Response in Biotype-1 Study

This study is looking for people aged 18-60 with schizophrenia, schizoaffective disorder, or bipolar 1 disorder to see how clozapine works for them. Researchers want to understand if people with a specific brain activity pattern (called Biotype 1) respond better to clozapine compared to another medication, risperidone. They will measure changes in your symptoms using a scale called the PANSS total score at weeks 4, 10, and 18. The study is currently unclear about its recruitment status, but plans to enroll 524 participants.

Study design: This is a multisite, randomized, double-blinded study comparing clozapine and risperidone. It plans to enroll 524 participants.
What's involved: Not specified in the trial record.
Compensation: Not stated in the trial record.
Follow-up: Your symptoms will be measured at Week 4, Week 10, and Week 18.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

CLOZAPINE Response in Biotype-1

Recruiting

PHASE4Ages 18–60InterventionalTreatment

University of Texas Southwestern Medical Center

~524 participants

Updated 2026-05-11 on ClinicalTrials.gov

What's tested:clozapinerisperidone

At a glance

Recruiting sites

5 of 5 listed sites are recruiting right now

RecruitingSuspended, closed, or not yet open

What they're measuring

Change in the PANSS total score

Measured over Week 4, Week 10 and Week 18

Conditions

Schizophrenia

Schizoaffective Disorder

Bipolar 1 Disorder

Where it's being run

5 sites across 5 states

Connecticut1

Georgia1

Illinois1

Massachusetts1

Texas1

Study leadership

Carol Tamminga, M.D. · PRINCIPAL_INVESTIGATOR · University of Texas Southwestern Medical Center

Who to contact

Asha Philip

[email protected]

214-648-5276 · ext. 85276

Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

18-60y/o; males and females; all races and ethnicities; able to provide written informed consent; able to read, speak, and understand English; medically stable; meeting DSM-IV (SCID-based) criteria for schizophrenia, schizoaffective disorder, or bipolar I disorder with psychotic features (we will use DSM-IV to be consistent with prior B-SNIP samples); PANSS total score of ≥70 and at least one item scored ≥5 or two items scored ≥4 on PANSS Positive Subscale; normal baseline values for absolute neutrophil count (ANC above 1500/mm3)

Exclusion

premorbid intellectual ability estimate below 70 (WRAT-4, Word Reading subtest, age-corrected standardized score); comorbid DSM-IV diagnosis of alcohol or substance abuse in prior 1 month or substance dependence in prior 3 months; neurological (e.g., seizure disorder, stroke, traumatic brain injury with a loss of consciousness ≥ 30min) or severe medical condition (e.g., decompensated cardiovascular disorder, AIDS) that may affect central nervous system function; concomitant medications known to affect EEG properties (i.e., lithium, anticonvulsants, benzodiazepines) or strong CYP 1A2 inhibitors (e.g., ciprofloxacin, enoxacin) or strong CYP 3A4 inducers (e.g., phenytoin, carbamazepine, phenobarbital, rifampin) which cannot be safely discontinued; vulnerable populations (e.g., pregnant, nursing, incarcerated); unwilling to use reliable means of contraception; history of neuroleptic malignant syndrome; prior treatment with clozapine, prior treatment with long-acting injectable antipsychotics that are 1-month formulations within the past 3 months and for 3-month formulations within the past 6 months; intolerable side effects to either clozapine or risperidone in lifetime, or a previously failed trial of either clozapine or risperidone at adequate doses in lifetime; history of drug reaction with eosinophilia and systemic symptoms syndrome (DRESS), also known as drug-induced hypersensitivity syndrome (DIHS); high risk for suicide defined as more than 1 attempt in past 12 months that required medical attention, any attempt in the past 3 months or current suicidal ideation with plan and intent such that outpatient care is precluded; current homicidal ideation with plan and intent such that outpatient care is precluded.

What this trial measures

Change in the PANSS total scoreWeek 4, Week 10 and Week 18
The change in the PANSS total score from the clinical trial baseline (W4) to the end of treatment (W18) will be a primary outcome measure. We predict that B1/clozapine will show a significantly larger change in the PANSS score from W4 to W18, compared to B1/risperidone, B2/clozapine and B2/risperidone. We will also examine the patterns of change in the PANSS score during the 'stable treatment' phase (W10-W18), across the same study groups. A mixed-effect repeated-measures ANCOVA \[2(Biotypes) × 2(clozapine/risperidone) × 2(time points\] will be used. We also predict that the reduction in the PANSS scores will correlate with increased IEA in B1/clozapine but not in B1/risperidone, B2/clozapine or B2/risperidone. Multivariate prediction models will be used.

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