Continuing clozapine with granulocyte colony-stimulating factor in patients with neutropenia

Clozapine rechallenge or continuation despite neutropenia or agranulocytosis using colony-stimulating factor: A systematic review

OBJECTIVES

Rechallenge/continuation of clozapine in association with colony-stimulating factors (CSFs) following neutropenia/agranulocytosis has been reported, but many questions remain unanswered about efficacy and safety. This systematic review aims to assess the efficacy and safety of rechallenging/continuing clozapine in patients following neutropenia/agranulocytosis using CSFs.

METHODS

MEDLINE, Embase, PsycInfo, and Web of Science databases were searched from inception date to July 31, 2022. Articles screening and data extraction were realized independently by two reviewers, according to Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 systematic review guidance. Included articles had to report on at least one case where clozapine was rechallenged/continued using CSFs despite previous neutropenia/agranulocytosis.

RESULTS

Eight hundred forty articles were retrieved; 34 articles met the inclusion criteria, totaling 59 individual cases. Clozapine was successfully rechallenged/continued in 76% of patients for an average follow-up period of 1.9 years. There was a trend toward better efficacy reported in case reports/series, compared with consecutive case series (overall success rates of 84% and 60%, respectively, p-value = 0.065). Two administration strategies were identified, "as-needed" and prophylactic, both yielding similar success rates (81% and 80%, respectively). Only mild and transient adverse events were documented.

CONCLUSIONS

Although limited by the relatively small number of published cases, factors such as time of onset to first neutropenia and severity of the episode did not seem to impact the outcome of a subsequent clozapine rechallenge using CSFs. While the efficacy of this strategy remains to be further adequately evaluated in more rigorous study designs, its long-term innocuity warrants considering its use more proactively in the management of clozapine hematological adverse events as to maintain this treatment for as many individuals as possible.

Clozapine re-challenge and initiation following neutropenia: a review and case series of 14 patients in a high-secure forensic hospital

OBJECTIVE

Clozapine remains the most effective intervention for treatment resistant schizophrenia; however, its use is prohibited following neutropenias. We review neutrophil biology as applied to clozapine and describe the strategies to initiate clozapine following neutropenia used in a case series of 14 consecutive patients rechallenged in a United Kingdom (UK) high-secure psychiatric hospital. We examine outcomes including the use of seclusion and transfer.

METHODS

A case series of 14 male patients with treatment resistant schizophrenia treated with clozapine despite previous episodes of neutropenia between 2006 and 2015 is presented. Data were collected during 2015 and 2019. Using this routinely collected clinical data, we describe the patient characteristics, causes of neutropenia, the strategies used for rechallenging with clozapine and clinical outcomes.

RESULTS

Previous neutropenias were the result of benign ethnic neutropenia, clozapine, other medications and autoimmune-related. Our risk mitigation strategies included: granulocyte-colony stimulating factor (G-CSF), lithium and watch-and-wait. There were no serious adverse events; at follow up half of the patient's had improved sufficiently to transfer them to conditions of lesser security. There were dramatic reductions in the use of seclusion.

CONCLUSION

Even in this extreme group, clozapine can be safely and effectively re/initiated following neutropenias, resulting in marked benefits for patients. This requires careful planning based on an understanding of neutrophil biology and the aetiology of the specific episode of neutropenia.

Clozapine rechallenge and initiation despite neutropenia- a practical, step-by-step guide

Clozapine remains the only drug treatment likely to benefit patients with treatment resistant schizophrenia. Its use is complicated by an increased risk of neutropenia and so there are stringent monitoring requirements and restrictions in those with previous neutropenia from any cause or from clozapine in particular. Despite these difficulties clozapine may yet be used following neutropenia, albeit with caution. Having had involvement with 14 cases of clozapine use in these circumstances we set out our approach to the assessment of risks and benefits, risk mitigation and monitoring with a practical guide.

Need to bleed? Clozapine haematological monitoring approaches a time for change

Regular haematological monitoring during clozapine treatment reduces the risk of complications and death from clozapine-related blood dyscrasias. However, many patients in the course of clozapine treatment develop neutropenia unrelated to drug treatment which leads to treatment discontinuation. The minimum haematological threshold allowed for the continuation of clozapine treatment was recently lowered in the US, but not in the UK. In this case series, we present four cases where lowering the haematological cut-off to that used in the US, allowed treatment continuation. Lowering the current UK threshold for clozapine cessation could avoid unnecessary interruptions in treatment with minimal impact on safety.

Re-titration rates after clozapine-induced neutropenia or agranulocytosis: A case report and literature review

Clozapine-induced neutropenia occurs in 3-5% of individuals treated with clozapine. Current US guidelines require interruption of clozapine when the absolute neutrophil count (ANC) drops below 1000 cells/mm3. There is minimal available guidance for what dosing schedule to use when restarting clozapine after an episode of neutropenia. Here, we present a case of a 50-year-old Caucasian female with a history of schizoaffective disorder who was successfully rechallenged on clozapine one month after developing clozapine-induced neutropenia (ANC 600 cells/mm3). To understand published re-titration rates of clozapine after neutropenia, we conducted a literature review using a using the PubMed database and found only seven case reports that unambiguously reported a clozapine dosing schedule during re-challenge. All were successful except one, a case of clozapine rechallenge after agranulocytosis. Including this case presentation, six out of eight cases restarted clozapine more cautiously than recommended by the US guidelines for a new clozapine initiation. We cannot comment what role a slower or more rapid titration plays in a successful rechallenge after neutropenia with the available evidence. We encourage researchers to publish their dosing schedule in detail after an episode of neutropenia or agranulocytosis.

The Use of Granulocyte Colony-Stimulating Factor in Clozapine Rechallenge: A Systematic Review

PURPOSE/BACKGROUND

Clozapine is associated with hematological abnormalities, with neutropenia and agranulocytosis of most concern. Granulocyte colony-stimulating factor (G-CSF) has been used to support clozapine rechallenge after neutropenia with the aim of maintaining the neutrophil count. This study aims to explore the practice, use, safety, and efficacy of G-CSF in this context.

METHODS/PROCEDURES

We conducted a systematic review to identify all studies investigating or describing G-CSF as a prophylaxis to enable continued clozapine treatment during a rechallenge.

FINDINGS/RESULTS

We identified 32 reports of patients who received G-CSF either regularly (n = 23) or as required (n = 9) to support clozapine rechallenge after an episode of neutropenia necessitating discontinuation of clozapine. Seventy-five percent (n = 24) of published cases remained on clozapine with the use of continual prophylactic G-CSF or after single G-CSF administrations (n = 8). Seventy percent (n = 16) of patients in receipt of continual prophylactic G-CSF were successfully maintained on clozapine. However, 1 of the 3 episodes of rechallenge in those with a history of severe agranulocytosis (absolute neutrophil count <0.1 × 10/L) had a recurrence of agranulocytosis at week 9.

IMPLICATIONS/CONCLUSIONS

Our findings suggest that G-CSF can sometimes be safely used to support the maintenance of normal neutrophil counts and clozapine use after neutropenia. Publication bias is an important limitation, however. Also, few reports clearly documented the presence or absence of an independent nonclozapine cause of the index neutropenia, which may have increased success rates. Furthermore, adverse events were not systematically recorded. Prospective studies are needed to determine safety because if agranulocytosis occurs on clozapine while supported by G-CSF, there is no obvious alternate rescue therapy to promote granulopoiesis. From the available data, it is not possible to recommend this course of action for someone with a true clozapine agranulocytosis.

Use of granulocyte-colony stimulating factor to prevent recurrent clozapine-induced neutropenia on drug rechallenge: A systematic review of the literature and clinical recommendations

BACKGROUND

Clozapine is the most effective medication for treatment-refractory schizophrenia; however, its use is contraindicated in people who have had previous clozapine-induced neutropenia. Co-prescription of granulocyte-colony stimulating factor may prevent recurrent neutropenia and allow continuation or rechallenge of clozapine.

OBJECTIVE AND METHODS

Systematic review of literature reporting the use of granulocyte-colony stimulating factor to allow rechallenge or continuation of clozapine in people with previous episodes of clozapine-induced neutropenia. The efficacy of granulocyte-colony stimulating factor and predictors of successful rechallenge will be determined to elucidate whether evidence-based recommendations can be made regarding the use of granulocyte-colony stimulating factor in this context.

RESULTS

A total of 17 articles were identified that reported on clozapine rechallenge with granulocyte-colony stimulating factor support. In all, 76% of cases were able to continue clozapine at median follow-up of 12 months. There were no clear clinical or laboratory predictors of successful rechallenge; however, initial neutropenia was more severe in successful cases compared to unsuccessful cases. Cases co-prescribed lithium had lower success rates of rechallenge (60%) compared to those who were not prescribed lithium (81%). The most commonly reported rechallenge strategy was use of filgrastim 150-480 µg between daily to three times a week. There were no medication-specific side effects of granulocyte-colony stimulating factor reported apart from euphoria in one case. Three cases who failed granulocyte-colony stimulating factor had bacterial infection at time of recurrent neutropenia. No deaths were reported.

CONCLUSION

Preliminary data suggest granulocyte-colony stimulating factor is safe and effective in facilitating rechallenge with clozapine. Clinical recommendations for use are discussed.

[Clozapine rechallenge after neutropenia in resistant schizophrenia: A review]

INTRODUCTION

Clozapine is an atypical antipsychotic known for its efficacy in refractory schizophrenia. One of the adverse effects is neutropenia. This dysplasia is a rare but major side effect which leads to a discontinuation and constitutes further contraindication. Thereafter, therapeutic options decrease dramatically. Mechanisms involved are not well known at this time and can be combined. A toxic hypothesis may be more likely than an immune-allergic one.

METHODS

We have reviewed publications on Medline describing procedures that allowed clozapine rechallenge after blood dyscrasia in refractory schizophrenia. Three different procedures were found: simple rechallenge, rechallenge with lithium and rechallenge with Granulocyte - colony stimulating factor (G-CSF). Rechallenge could be simple or multiple.

RESULTS

These past years, clozapine have been rechallenged successfully after neutropenia thanks to different procedures, the different options being simple rechallenge, rechallenge with lithium and/or rechallenge with G-CSF. Lithium as G-CSF are used to increase neutrophil blood rate and prevent neutropenia recurrence after clozapine rechallenge. G-CSF was first used within the context of chemotherapy and extends now to clozapine-induced neutropenia. Both for lithium and G-CSF, numerous procedures are reviewed and cannot be compared.

DISCUSSION

Publications are limited but increasing, and they point out that a careful rechallenge can be successful. However, interesting data can be extracted. First, clozapine is more likely to be incriminated in neutropenia when patients receive many drugs, but a careful study could prevent some discontinuation. Indeed, other drugs or a hematologic disease could be involved. Moreover, several contributing factors have been found such as HLA group and drug interaction. Ethnic origin also affects neutrophil rate. That is why, in Great Britain, a subgroup of patients "benign ethnic neutropenia" has been introduced to enlarge threshold and allow these patients to access clozapine despite lower blood counts. Then, rechallenge choice has to be done on a case-by-case basis and only after considering the benefits and risks of such a treatment. Most of the time, clinical advice of rechallenge arises from the inefficiency of other antipsychotics and even sismotherapy failure. Patients and sometimes families have to be informed and give their consent. Preventive measures have been found such as taking a hematologic recommendation and doing twice-a-week blood sample monitoring. With regards lithium and G-CSF, some efficient doses are assumed (lithium: 0,4-1,1 mEq/L and G-CSF>0,3 mg/week). Lithium as G-CSF may have other adverse effects which need to be considered. There is no successful rechallenge reported after agranulocytosis. Some publications highlight that if neutropenia occurs on rechallenge, it will do so more quickly and more severe than at the time of initial trial of clozapine.

CONCLUSION

There is emerging evidence of successful clozapine rechallenging. However, further investigations are required as randomized controlled trials to reassess guidelines and establish the safety and effectiveness of the different procedures. Because of the practical and ethical difficulties of designing such studies, referral hospitals could be elected, and common background writing proposed in order to ease data comparison.

Continuing clozapine treatment with lithium in schizophrenic patients with neutropenia or leukopenia: brief review of literature with case reports

OBJECTIVE

Clozapine is a second-generation antipsychotic used for treatment-resistant schizophrenia. Despite its effectiveness, clozapine is largely underused due to serious side effects such as leukopenia or neutropenia. We aimed to review whether to continue, discontinue or rechallenge clozapine treatment after such haematological side effects.

METHODS

We reviewed and summarized the literature on the use of clozapine, how to deal with its side effects, and suitable options in case of any haematological problems. Then, we described several cases successfully treated with clozapine and lithium after development of neutropenia or leukopenia.

RESULTS

We present three patients with treatment-resistant schizophrenia. While they had demonstrated poor response to multiple antipsychotic trials, clozapine was started. Clozapine induced neutropenia; or leukopenia developed in some cases that was successfully reversed after lithium onset. Increased serious side effects related with coprescription of lithium and clozapine were not observed.

CONCLUSION

Lithium increases neutrophil and total white blood cell count as a side effect that may be useful in patients who develop neutropenia or leukopenia while being treated with clozapine.

Effect of Adenine on Clozapine-induced Neutropenia in Patients with Schizophrenia: A Preliminary Study

Objective

This study examined the utility of adenine for preventing clozapine-induced neutropenia.

Methods

This retrospective study examined the effect of adenine on clozapine-induced neutropenia in patients with treatment-resistant schizophrenia and was conducted at Okehazama Hospital in Japan from July 2010 to June 2013. Adenine was available for use from June 2011 onwards. Twenty-one patients started receiving clozapine treatment from July 2010 to April 2011 (the pre-adenine adoption group), and 47 patients started receiving it from May 2011 to June 2013 (the post-adenine adoption group). The effects of adenine were assessed based on changes in the patients’ leukocyte counts and the frequency of treatment discontinuation due to clozapine-induced neutropenia.

Results

Sixty-eight patients were treated with clozapine from July 2010 to June 2013. Of the 21 patients in the pre-adenine adoption group, 4 discontinued treatment due to clozapine-induced neutropenia, whereas only 2 of the 47 patients in the post-adenine adoption group discontinued treatment. The frequency of treatment discontinuation due to clozapine-induced neutropenia was significantly lower in post-adenine adoption group than in the pre-adenine adoption group (p=0.047).

Conclusion

Adenine decreased the frequency of treatment discontinuation due to clozapine-induced neutropenia. Our data suggest that combined treatment with clozapine and adenine is a safe and effective strategy against treatment-resistant schizophrenia.

Clozapine promotes the proliferation of granulocyte progenitors in the bone marrow leading to increased granulopoiesis and neutrophilia in rats

Clozapine is an atypical antipsychotic that is limited in its use due to the risk of idiosyncratic agranulocytosis. The bone marrow is suspected to be the site of the reaction, and indirect measurements in patients suggest that neutrophil production and maturation are altered in the marrow by clozapine. Specifically, the majority of patients have elevated neutrophil counts at the start of treatment, often paired with increased serum granulocyte-colony stimulating factor (G-CSF). Employing a rat model of clozapine treatment, we set out to determine if the neutrophilia observed at the start of treatment is characteristic of G-CSF-associated bone marrow stimulation. Female Sprague-Dawley rats were treated with 30 mg/kg/day of clozapine for 10 days, and sustained neutrophilia was evident after 1 week of treatment paired with spikes in G-CSF. Within the bone marrow, clozapine was found to induce proliferation of the granulocyte progenitor colonies as measured by a methylcellulose assay. This led to elevated granulopoiesis observed by H&E and myeloperoxidase staining of bone marrow slices. Increased release of neutrophils from the marrow to the circulation was measured through 5-bromo-2'-deoxyuridine labeling in vivo, and these neutrophils appeared to be less mature based on (a) a decrease in the nuclear lobe count and (b) increased expression of surface CD62L. Furthermore, faster transit of the neutrophils through the marrow was suggested by a shift toward elevated numbers of neutrophils in the bone marrow maturation pool and increased CD11b and CD18 staining on the less mature neutrophils residing in the marrow. Taken together, these data indicate that clozapine stimulates the bone marrow to produce more neutrophils in a manner that is characteristic of endogenous G-CSF stimulation, and it is consistent with the inflammatory response observed in patients treated with clozapine.

Management and prevention of agranulocytosis in patients receiving clozapine

Clozapine is an antipsychotic associated with superior efficacy compared to other atypical antipsychotics in the treatment of schizophrenia. However, clozapine use is limited due to its association with a rare but potentially fatal adverse effect, agranulocytosis. Patients receiving clozapine therapy require frequent monitoring of white blood cell (WBC) and absolute neutrophil counts (ANC). This article reviews the monitoring parameters for patients receiving clozapine therapy, and the management and prevention of clozapine-associated agranulocytosis.