Add-on filgrastim during clozapine rechallenge in patients with a history of clozapine-related granulocytopenia/agranulocytosis

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.

Clozapine Rechallenge After Major Adverse Effects: Clinical Guidelines Based on 259 Cases

BACKGROUND

Clozapine is widely prescribed for treatment-refractory schizophrenia, but its use is limited by many potentially life-threatening adverse effects. The risk of rechallenge after these complications has never been comprehensively assessed in controlled studies. Thus, clinical guidelines must rely on the published case reports. The number of such reports is likely to increase over time, and updated analyses of larger samples are needed, as they may lead to changes in clinical guidelines.

STUDY QUESTIONS

How safe is the clozapine rechallenge after life-threatening adverse effects?

STUDY DESIGN

The published case reports of clozapine rechallenge were identified in a MEDLINE search. We added 121 cases reported from 2012 through 2017 to the 138 cases reported from 1972 through 2011 analyzed by us in a previous publication. The 95% confidence intervals (CIs) of the successful rechallenge rate were calculated for each adverse effect with at least 5 published case reports. The rechallenge was considered a valid clinical option when the lower end of the CI range was at least 50%.

RESULTS

A successful outcome was documented in 128/203 patients rechallenged after neutropenia (63.0%, CI, 56.0%-69.6%), 3/17 after agranulocytosis (17.7%, CI, 4.7%-44.2%), 11/17 after myocarditis (64.7%, CI, 38.6%-84.7%), and 7/7 after neuroleptic malignant syndrome (100%, CI, 56.1%-100%). Among the 15 patients with other clozapine-induced adverse effects, the rechallenge was successful in those with eosinophilia, cardiac complications other than myocarditis (QTc prolongation, pericarditis, cardiomyopathy, and atrial flutter), and gastrointestinal hypomotility. The rechallenge failed in patients who had developed pancreatitis or renal insufficiency.

CONCLUSION

Clozapine rechallenge is a reasonable clinical option after return to baseline for patients who had developed neutropenia and neuroleptic malignant syndrome, but not after agranulocytosis or myocarditis. Data are insufficient to formulate rechallenge guidelines for any other clozapine-related adverse effects.

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.

Safety of antipsychotics for the treatment of schizophrenia: a focus on the adverse effects of clozapine

Clozapine, a dibenzodiazepine developed in 1961, is a multireceptorial atypical antipsychotic approved for the treatment of resistant schizophrenia. Since its introduction, it has remained the drug of choice in treatment-resistant schizophrenia, despite a wide range of adverse effects, as it is a very effective drug in everyday clinical practice. However, clozapine is not considered as a top-of-the-line treatment because it may often be difficult for some patients to tolerate as some adverse effects can be particularly bothersome (i.e. sedation, weight gain, sialorrhea etc.) and it has some other potentially dangerous and life-threatening side effects (i.e. myocarditis, seizures, agranulocytosis or granulocytopenia, gastrointestinal hypomotility etc.). As poor treatment adherence in patients with resistant schizophrenia may increase the risk of a psychotic relapse, which may further lead to impaired social and cognitive functioning, psychiatric hospitalizations and increased treatment costs, clozapine adverse effects are a common reason for discontinuing this medication. Therefore, every effort should be made to monitor and minimize these adverse effects in order to improve their early detection and management. The aim of this paper is to briefly summarize and provide an update on major clozapine adverse effects, especially focusing on those that are severe and potentially life threatening, even if most of the latter are relatively uncommon.

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.

Medical management of patients on clozapine: A guide for internists

Clozapine was approved by the US Food and Drug Administration in 1989 for the management of treatment-resistant schizophrenia, and has since proven to reduce symptom burden and suicide risk, increase quality of life, and reduce substance use in individuals with psychotic disorders. Nevertheless, clozapine's psychiatric benefits have been matched by its adverse effect profile. Because they are likely to encounter medical complications of clozapine during admissions or consultations for other services, hospitalists are compelled to maintain an appreciation for these iatrogenic conditions. The authors outline common (eg, constipation, sialorrhea, weight gain) and serious (eg, agranulocytosis, seizures, myocarditis) medical complications of clozapine treatment, with internist-targeted recommendations for management, including indications for clozapine discontinuation.

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

BACKGROUND

The current guidelines dictate that clozapine should be stopped following the emergence of neutropenia. Various alternative approaches have been tried in the past, among them one rarely used alternative being to continue treatment with clozapine with coprescription of granulocyte colony-stimulating factor (G-CSF).

AIM AND METHOD

In this case series we aim to describe the treatment and progress of a number of patients in a secure psychiatric hospital in the UK. These patients were restarted on clozapine in combination with G-CSF, in spite of previous neutropenia associated with clozapine treatment.

DISCUSSION AND CONCLUSION

We hope that this case series will raise the profile of a potentially effective alternative to discontinuing clozapine after neutropenia.

Add-on filgrastim during clozapine rechallenge unsuccessful in preventing agranulocytosis

Granulocyte colony-stimulating factor agents such as filgrastim can be administered in order to reduce the duration of clozapine-induced agranulocytosis. Successful long-term combination treatment with filgrastim and clozapine in patients with previous clozapine-induced agranulocytosis has been described in several cases. We describe a patient with schizophrenia who developed agranulocytosis during treatment with clozapine and who did not respond to other antipsychotics. Add-on treatment with filgrastim during a clozapine rechallenge did not prevent the reoccurrence of agranulocytosis, and clozapine treatment had to be discontinued. Our case suggests that add-on filgrastim is a therapeutic option when clozapine is rechallenged, but physicians should be aware of the potential dangers especially severe clozapine-induced agranulocytosis.

Granulocyte colony stimulating factor (G-CSF) can allow treatment with clozapine in a patient with severe benign ethnic neutropaenia (BEN): a case report

Clozapine is the treatment of choice for treatment-resistant schizophrenia, but it is associated with a risk of neutropaenia and agranulocytosis. Clozapine use is regulated by mandatory blood monitoring in the UK, requiring cessation of treatment should the absolute neutrophil count (ANC) drop below specified values. Benign reductions in the ANC in non-white populations are common, and this can preclude a patient from receiving treatment with clozapine. A diagnosis of benign ethnic neutropaenia can reduce these treatment restrictions (UK specific), but the degree of neutropaenia can be significant enough to still prevent treatment. In this report, we show that response to granulocyte colony stimulating factor (G-CSF) may be quite variable and difficult to predict, but with careful monitoring it can be used to increase the ANC count and allow continued treatment with clozapine.

When can patients with potentially life-threatening adverse effects be rechallenged with clozapine? A systematic review of the published literature

BACKGROUND

Clozapine is widely prescribed for treatment refractory patients with schizophrenia, but its use is limited by potentially life threatening adverse effects. Rechallenge after these complications has been occasionally attempted in patients with severe psychotic symptoms.

OBJECTIVE

To review the outcome of clozapine rechallenge after potentially life threatening adverse effects.

METHODS

Electronic, all-language, literature search (1972-2011) followed by demographic and clinical data extraction. The outcome of rechallenge was considered favorable when the lower bound of the 95% confidence interval (CI) of the proportion of patients who could continue clozapine was >50%.

RESULTS

Altogether, 138 patients (mean age: 36.3years, 65.7% male, 57.6% Caucasian, virtually all with schizophrenia spectrum diagnosis) underwent clozapine rechallenge after developing neutropenia (n=112), agranulocytosis (n=15), neuroleptic malignant syndrome (NMS) (n=5), myocarditis (n=4), pericarditis (n=1) and lupus erythematosus (n=1). Rechallenge strategies were heterogeneous and not systematically evaluated. Clozapine rechallenge was successful in 78/112 patients (69.6%, CI: 60.6-77.4) after neutropenia, 3/15 (20%, CI: 7.1-45.2) after agranulocytosis, 5/5 (100%, CI: 56-100) after NMS, 3/4 (75%, CI: 30-95) after myocarditis, 1/1 after pericarditis, and 0/1 after clozapine-induced lupus. Successfully rechallenged patients were followed for 16-96weeks. None of the rechallenged patients died.

CONCLUSIONS

Although controlled studies are clearly needed, using a priori, confidence interval-based criteria, case reports/series suggest that in refractory patients who benefited from clozapine, careful rechallenge can be considered after neutropenia and NMS, but not after agranulocytosis and myocarditis.

Haematological toxicity of clozapine and some other drugs used in psychiatry

OBJECTIVE

To review recent work on the haematological toxicity of clozapine and some other drugs used in psychiatry concerning especially (i) the mechanism of antipsychotic-induced neutropenia/agranulocytosis, (ii) criteria for clozapine prescribing in benign ethnic neutropenia, (iii) options in the event of worrying falls in white cell count (WCC), including measures to boost WCC with or without continued clozapine administration, (iv) criteria for clozapine rechallenge in the event that treatment was suspended because of a fall in WCC and (v) safety concerns regarding clozapine in children/adolescents.

CONCLUSIONS

There remain several difficult areas, including the criteria for clozapine rechallenge. Experience has emphasised (i) the role of appropriate timing of WCC sample collection to ensure that clozapine is not withdrawn unnecessarily and (ii) the success of agents such as filgrastim in promoting rapid production of granulocytes if the situation so demands. On the other hand, the use of lithium to promote a leucocytosis has taken hold without a clear risk: benefit analysis. Be this as it may, should patients decide that they no longer wish to undergo WCC monitoring after 12 months on clozapine, cessation of monitoring is probably preferable to stopping the drug since overall mortality is decreased in patients treated with clozapine.