2026 Eastern States Conference

Title: Impact of clozapine risk evaluation and mitigation strategy (REMS) removal on absolute neutrophil count (ANC) monitoring

Authors: Rhonda Moton (PharmD), Seema Ledan (PharmD), Jessica Ho (PharmD, BCPS, BCPP), Kristen Fink (PharmD, BCPS, BCACP, CDCES)

Learning objective: Audience members will be able to analyze the impact of the removal of the clozapine REMS program on monitoring practices of pharmacists and psychiatrists at a managed care institution

Self-Assessment Question:
True/False: Currently, clozapine therapy requires regular monitoring of a patient’s absolute neutrophil count (ANC) to ensure safe continuation of treatment.

Background: Clozapine treats resistant schizophrenia but is underused due to risks like agranulocytosis. After REMS ended in 2025, this study evaluates how its removal affected ANC monitoring over a 6-month period before and after REMS discontinuation.

Methods: Patients treated with clozapine from August 25, 2023 to August 25, 2025 were identified for evaluation. ANC data will be reviewed and compared across the six months before and after REMS discontinuation to determine any meaningful shifts in monitoring practices. The primary outcome is the frequency of ANC monitoring completed per patient over a 12-month period. Secondary outcomes include number of clozapine prescriptions not dispensed due to missing ANC values, the incidence and severity of neutropenia events, and rates of hospital, emergency department (ED), or urgent care visits related to psychosis. Additional measures include the number of new clozapine starts before and after REMS removal, as well as demographics, comorbidities, and encounter types gathered for context. Statistical analysis will use chi-square testing for the primary objective and descriptive methods for secondary outcomes. The project was reviewed and approved by Kaiser Permanente’s Institutional Review Board.

Results: Sixty-three clozapine patients were evaluated-59 pre-REMS and 58 post-REMS. All patients completed required ANC monitoring in both six-month periods, resulting in no variability and preventing chi-square analysis; thus, indicating no p-value. No prescriptions were denied for missing labs. Hematologic events were rare: one patient had mild neutropenia and another showed persistent neutrophilia. Fifty-nine patients started clozapine before REMS removal and four after. Pre-REMS, three patients required acute psychiatric care, while one post-REMS patient had increased psychiatric-related healthcare use, including multiple service encounters, follow-up visits, and additional outpatient visits to address ongoing symptoms.

Conclusion: Clozapine REMS discontinuation did not reduce adherence to ANC monitoring, which remained 100% in both pre- and post-REMS groups. No prescriptions were denied for missing labs, and hematologic events were rare. Few new clozapine starts occurred after REMS removal, suggesting institutional practices continued to support consistent monitoring. Larger studies with extended follow-up are needed to better evaluate potential long-term effects of REMS discontinuation more clearly.