Complications of clozapine cessation in the context of chemotherapy-related neutropenia-a case report.
- 1Department of Psychological Medicine, St James Hospital, Dublin, Ireland.
- 2St Patrick's University Hospital, Dublin, Ireland.
- 3Department of Oncology, St James Hospital, Dublin, Ireland.
Abstract
Background
Clozapine is the gold standard for treatment-resistant schizophrenia (TRS). It requires strict monitoring of full blood count (FBC), due to the risk of neutropenia and agranulocytosis.Case history
AB is a woman in her mid-40s with TRS, diagnosed with invasive ductal carcinoma of the right breast. She was commenced on a chemotherapy regimen of docetaxel, carboplatin, trastuzumab, and pertuzumab. Four days after the initial infusion, AB developed neutropenia with an absolute neutrophil count of 0.2 × 10⁹/L. In accordance with local protocols and discussion with the Clozapine Patient Monitoring Service (CPMS), clozapine was immediately discontinued. Two weeks after clozapine cessation, AB displayed catatonic symptoms characterised by mutism, posturing, and automatic obedience, scoring 27 on the Bush-Francis Catatonia Rating Scale (BFCRS). A positive lorazepam challenge confirmed the diagnosis of clozapine-withdrawal catatonia. Despite regular high-dose benzodiazepines and treatment with antipsychotics, AB's presentation continued to deteriorate, characterised by prominent delusions and hallucinations, impeding oncological treatment. AB was seen extensively by liaison psychiatry and treated with high-dose typical and atypical antipsychotics; however, she failed to respond adequately to treatment. Given AB's extensive previous history of management on clozapine without previous haematological disturbance and ongoing decline in mental state, coupled with the timeline of symptoms 4 days after the administration of chemotherapy agents associated with neutropenia, namely, carboplatin, the decision was taken to reinstate clozapine. Following titration of clozapine and transfer to a specialist psychiatric unit, AB's symptoms resolved rapidly, allowing for the successful completion of chemotherapy. Carboplatin was omitted in subsequent cycles, with no further episodes of neutropenia.Discussion
This case highlights the diagnostic challenge of neutropenia in psychiatric patients on clozapine, who are also undergoing treatment for comorbid medical conditions. The presence of neutropenia in clozapine patients may lead to diagnostic overshadowing and delay the diagnosis of the underlying cause of neutropenia, resulting in delays to treatment as well as unnecessary cessation of clozapine and risk of relapse. Furthermore, this case highlights the risk of catatonia associated with the withdrawal of clozapine and the importance of its rapid identification and management.Conclusions
Clinicians should consider differing aetiologies of neutropenia in clozapine patients, especially those undergoing chemotherapy. Furthermore, clinicians should be skilled in recognising catatonia and initiating prompt treatment.
Related
- Unravelling the mechanisms of clozapine-induced neutropenia in treatment-resistant schizophrenia using cellular genomics
- Phlegmonous Gastritis in Chemotherapy-related Neutropenia with Endoscopic Findings that Prompted Early Therapeutic Intervention
- A phase 3 trial of GB-K02 pegfilgrastim biosimilar for preventing chemotherapy-induced neutropenia in breast cancer
- Smoking Cessation Duration and Diabetic Microvascular Complications
- Neoadjuvant Chemotherapy and Perioperative Complications Associated with Pulmonary Toxicity.
BibTeX
@article{sweeney2026complications,
title = {{Complications of clozapine cessation in the context of chemotherapy-related neutropenia-a case report.}},
author = {Colm Sweeney and Gavin Rush and Sarah O'Dwyer and Colm Mac Eochagain and Róisín Plunkett},
journal = {Frontiers in oncology},
year = {2026},
month = oct,
doi = {10.3389/fonc.2026.1863699},
url = {https://europepmc.org/article/MED/42903121},
note = {CC BY},
}
RIS
TY - JOUR
TI - Complications of clozapine cessation in the context of chemotherapy-related neutropenia-a case report.
AU - Colm Sweeney
AU - Gavin Rush
AU - Sarah O'Dwyer
AU - Colm Mac Eochagain
AU - Róisín Plunkett
PY - 2026
DA - 2026/10/06
JO - Frontiers in oncology
DO - 10.3389/fonc.2026.1863699
UR - https://europepmc.org/article/MED/42903121
AB - Background Clozapine is the gold standard for treatment-resistant schizophrenia (TRS). It requires strict monitoring of full blood count (FBC), due to the risk of neutropenia and agranulocytosis.Case history AB is a woman in her mid-40s with TRS, diagnosed with invasive ductal carcinoma of the right breast. She was commenced on a chemotherapy regimen of docetaxel, carboplatin, trastuzumab, and pertuzumab. Four days after the initial infusion, AB developed neutropenia with an absolute neutrophil count of 0.2 × 10⁹/L. In accordance with local protocols and discussion with the Clozapine Patient Monitoring Service (CPMS), clozapine was immediately discontinued. Two weeks after clozapine cessation, AB displayed catatonic symptoms characterised by mutism, posturing, and automatic obedience, scoring 27 on the Bush-Francis Catatonia Rating Scale (BFCRS). A positive lorazepam challenge confirmed the diagnosis of clozapine-withdrawal catatonia. Despite regular high-dose benzodiazepines and treatment with antipsychotics, AB's presentation continued to deteriorate, characterised by prominent delusions and hallucinations, impeding oncological treatment. AB was seen extensively by liaison psychiatry and treated with high-dose typical and atypical antipsychotics; however, she failed to respond adequately to treatment. Given AB's extensive previous history of management on clozapine without previous haematological disturbance and ongoing decline in mental state, coupled with the timeline of symptoms 4 days after the administration of chemotherapy agents associated with neutropenia, namely, carboplatin, the decision was taken to reinstate clozapine. Following titration of clozapine and transfer to a specialist psychiatric unit, AB's symptoms resolved rapidly, allowing for the successful completion of chemotherapy. Carboplatin was omitted in subsequent cycles, with no further episodes of neutropenia.Discussion This case highlights the diagnostic challenge of neutropenia in psychiatric patients on clozapine, who are also undergoing treatment for comorbid medical conditions. The presence of neutropenia in clozapine patients may lead to diagnostic overshadowing and delay the diagnosis of the underlying cause of neutropenia, resulting in delays to treatment as well as unnecessary cessation of clozapine and risk of relapse. Furthermore, this case highlights the risk of catatonia associated with the withdrawal of clozapine and the importance of its rapid identification and management.Conclusions Clinicians should consider differing aetiologies of neutropenia in clozapine patients, especially those undergoing chemotherapy. Furthermore, clinicians should be skilled in recognising catatonia and initiating prompt treatment.
SN - 2234-943X
ER -