Biomarker and Safety Study of Clozapine in Patients With Benign Ethnic Neutropenia (BEN)

Not Applicable

Completed

Conditions: Schizophrenia

Interventions: Drug: Clozapine

Registration Number: NCT02404155

Lead Sponsor: University of Maryland, Baltimore

Brief Summary: Clozapine (CLZ) is the most effective antipsychotic for treatment-refractory schizophrenia (SZ). Despite the overwhelming evidence of superior efficacy, CLZ is infrequently prescribed in the US, at a considerably lower rate than the estimated prevalence of treatment-resistant SZ, especially for African-Americans (AA). Recent evidence suggests that low Absolute Neutrophil Counts (ANC), either at baseline or during treatment are a significant barrier to CLZ use in AA patients in the US, where guidelines mandate CLZ discontinuation if ANC drops below 1500 cells/mm3. The investigators group has found that discontinuation of CLZ in AA patients is over twice that in European-American (EA) patients (N\~400; 42% vs.19%, P=0.041) and initiation rates are 50% lower. In a Statewide study (N=1875), the investigators reported that discontinuation was more frequently due to neutropenia in the AA sample, though no AA had developed agranulocytosis (8 cases in EA). Benign Ethnic Neutropenia (BEN) in people of African ancestry, including AAs, identifies a group (50% of AA) with low ANCs but no increased risk of agranulocytosis or infection. Low baseline or in-treatment fluctuations requiring CLZ discontinuation under current prescribing guidelines are common in CLZ-treated persons with BEN. In the investigators recent pilot study of N=12 AA patients with BEN, treatment was safely and successfully continued with CLZ despite low baseline ANC (outside current guidelines). Recent evidence implicates a polymorphism in the Duffy Antigen Receptor Chemokine (DARC) gene in the pathophysiology of BEN. In homozygotes (FY-/-) for the DARC null allele, mean within-subject neutrophil counts are reduced, resulting in sporadic ANC \<1500 cells/mm3 in 10-15% of people with the allele. In population studies, the FY-/- genotype is found in 0.01% of EAs, 99.3% of sub-Saharan Africans (SSA), and 68% of AAs. Further, a missense DARC mutation has been reported to interact with the DARC FY-/- in determining low WBC in AAs. Normal patterns of week-to-week fluctuation in ANC levels in individuals of African ancestry with BEN and the DARC null genotype are not known, and no published research has examined variation in ANC in African ancestry CLZ-treated SZ patients with BEN and the DARC null genotype (FY-/-). Such data are also lacking on individuals with BEN without the DARC null genotype. Conducting such research will generate genetic marker and safety data that could be used to expand access to CLZ for AA patients who otherwise are eligible to receive this superior treatment option.

Detailed Description: Not available

Recruitment & Eligibility

Status: COMPLETED

Sex: All

Target Recruitment: 274

Inclusion Criteria

Not provided

Exclusion Criteria

Not provided

Study & Design

Study Type: INTERVENTIONAL

Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
Clozapine	Clozapine	-

Primary Outcome Measures

Name	Time	Method
Change in White Blood Cell (WBC) (mm3) and Absolute Neutrophil Counts (ANC) (mm3) in Persons According to Presence of the DARC Null Allele.	24 week period baseline and endpoint
Number of Episodes of Agranulocytosis (Count).	6 months

Secondary Outcome Measures