Treatment of invasive fungal diseases in cancer patients-Revised 2019 Recommendations of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Oncology (DGHO)

BACKGROUND

Invasive fungal diseases remain a major cause of morbidity and mortality in cancer patients undergoing intensive cytotoxic therapy. The choice of the most appropriate antifungal treatment (AFT) depends on the fungal species suspected or identified, the patient's risk factors (eg length and depth of granulocytopenia) and the expected side effects.

OBJECTIVES

Since the last edition of recommendations for 'Treatment of invasive fungal infections in cancer patients' of the Infectious Diseases Working Party (AGIHO) of the German Society of Hematology and Medical Oncology (DGHO) in 2013, treatment strategies were gradually moving away from solely empirical therapy of presumed or possible invasive fungal diseases (IFDs) towards pre-emptive therapy of probable IFD.

METHODS

The guideline was prepared by German clinical experts for infections in cancer patients in a stepwise consensus process. MEDLINE was systematically searched for English-language publications from January 1975 up to September 2019 using the key terms such as 'invasive fungal infection' and/or 'invasive fungal disease' and at least one of the following: antifungal agents, cancer, haematological malignancy, antifungal therapy, neutropenia, granulocytopenia, mycoses, aspergillosis, candidosis and mucormycosis.

RESULTS

AFT of IFDs in cancer patients may include not only antifungal agents but also non-pharmacologic treatment. In addition, the armamentarium of antifungals for treatment of IFDs has been broadened (eg licensing of isavuconazole). Additional antifungals are currently under investigation or in clinical trials.

CONCLUSIONS

Here, updated recommendations for the treatment of proven or probable IFDs are given. All recommendations including the levels of evidence are summarised in tables to give the reader rapid access to key information.

The management of anti-infective agents in intensive care units: the potential role of a 'fast' pharmacology

INTRODUCTION

Patients in intensive care units (ICU) are often developing severe infections in which are associated with significant mortality rates. A number of novel technologies for the rapid microbiological diagnosis of these infections have been developed, introducing the era of 'fast microbiology.' Treatment of bacterial and fungal infections in ICU is however complicated by alterations in the pharmacokinetics of antimicrobial agents.

AREAS COVERED

We review novel pharmacologic tools that can be used to optimize anti-infective therapies and patient management in ICU. A MEDLINE Pubmed search for articles published from January 1995 to 2019 was completed matching the terms pharmacokinetics and pharmacology with antimicrobial agents and ICU or critically ill patients. Moreover, additional studies were identified from the reference list of retrieved articles.

EXPERT OPINION

Several tools are in development for the full automation of the analytical methods used for the quantification of antimicrobial concentrations within a few hours after sample collection. Ad hoc software with adaptive feedback is also available for appropriate dose adjustments based on both individual patient covariate data and therapeutic drug monitoring (TDM) data when available. The application of these technological improvements in the clinical practice should open the way to a 'fast pharmacology' at the bedside.

Administration and Dosing of Systemic Antifungal Agents in Pediatric Patients

Neonates and immunosuppressed/immunocompromised pediatric patients are at high risk of invasive fungal diseases. Appropriate antifungal selection and optimized dosing are imperative to the successful prevention and treatment of these life-threatening infections. Conventional amphotericin B was the mainstay of antifungal therapy for many decades, but dose-limiting nephrotoxicity and infusion-related adverse events impeded its use. Despite the development of several new antifungal classes and agents in the past 20 years, and their now routine use in at-risk pediatric populations, data to guide the optimal dosing of antifungals in children are limited. This paper reviews the spectra of activity for approved antifungal agents and summarizes the current literature specific to pediatric patients regarding pharmacokinetic/pharmacodynamic data, dosing, and therapeutic drug monitoring.

Diagnosis and Treatment of Acute Invasive Fungal Sinusitis in Cancer and Transplant Patients

PURPOSE OF REVIEW

Modern advances in oncologic and end-organ therapies have led to an increase in immunocompromised patients and a corresponding rise in acute invasive fungal sinusitis (AIFS). Here, we present a comprehensive medical and surgical approach to the diagnosis and management of immunocompromised cancer and transplant patients with AIFS.

RECENT FINDINGS

Aspergillus and Mucorales are the most common fungi to cause AIFS, though atypical fungal pathogens have been implicated particularly among patients on azole prophylaxis. Symptoms present in the majority of AIFS cases include fever, nasal congestion, and facial swelling. Nasal endoscopy and radiology are adjuncts to clinical exam with the gold standard diagnostic test still being histopathology, though molecular testing such as panfungal PCR is playing a larger role. The treatment of AIFS requires surgery, antifungal therapy, and reversal of immunosuppression. We recommend initiation of liposomal amphotericin B as an empiric therapy for AIFS, transitioned to targeted therapy when/if a fungal pathogen is identified. Goals of surgery include diagnostic sampling and debridement of necrotic tissue. Equally, if not more important, is reversal of underlying immune suppression. Immune-stimulating therapies hold promise for reducing mortality, but require additional study. Despite improvements in medical and surgical management of AIFS, mortality continues to approach 50%. Early diagnosis of this disease entity followed by aggressive surgical and medical management are important, including reversal of the underlying immunosuppression.

Impact of dose adaptations following voriconazole therapeutic drug monitoring in pediatric patients

Voriconazole is the mainstay of treatment for invasive aspergillosis in immunocompromised pediatric patients. Although Therapeutic Drug Monitoring (TDM) of voriconazole is recommended, it remains unknown if TDM-based dose adaptations result in target attainment. Patients <19 years from two pediatric hematologic-oncology wards were retrospectively identified based on unexplained high voriconazole trough concentrations (Cmin > 6 mg/l). Patient demographics, clinical characteristics, treatment, voriconazole dosing information, voriconazole Cmin before and after adjustment based on TDM were obtained. Twenty-one patients, median (range) age 7.0 (1.2-18.5) years, were identified in two centers. First Cmin (3.1 mg/l [0.1-13.5]) was obtained after 3 days (1-27) of treatment. The median of all Cmin (n = 485, median 11 per patient) was 2.16 mg/l (0.0 (undetectable)-28.0), with 24.1% of Cmin < 1 mg/l, 48.9% 1-4 mg/l, 9.3% 4-6 mg/l, and 17.7% > 6 mg/l. Intrapatient variability was large (94.1% for IV, 88.5% for PO). Dose increases at Cmin < 1 mg/l resulted in an increased Cmin in 76.4%, with 60% between 1 and 4 mg/l. Dose decreases at Cmin > 6 mg/l resulted in a decreased Cmin in 80%, with 51% between 1 and 4 mg/l. Overall, in 45% of the cases (33 out of 55 and 12 out of 45) therapeutic targets were attained after dose adjustment. Fifty-five percent of initial Cmin was outside the therapeutic target of 1-4 mg/l, with multiple dose adaptations required to achieve therapeutic concentrations. Only 60% and 51% of dose adaptations following sub- and supra-therapeutic Cmin, respectively, did result in target attainment. Intensive and continuous TDM of voriconazole is a prerequisite for ensuring adequate exposure in pediatric patients.

Therapeutic drug monitoring of systemic antifungal agents: a pragmatic approach for adult and pediatric patients

Introduction: Therapeutic drug monitoring (TDM) has been shown to optimize the management of invasive fungal infections (IFIs), particularly for select antifungal agents with a well-defined exposure-response relationship and an unpredictable pharmacokinetic profile or a narrow therapeutic index. Select triazoles (itraconazole, voriconazole, and posaconazole) and flucytosine fulfill these criteria, while the echinocandins, fluconazole, isavuconazole, and amphotericin B generally do not do so. Given the morbidity and mortality associated with IFIs and the challenges surrounding the use of currently available antifungal agents, TDM plays an important role in therapy.Areas covered: This review seeks to describe the rationale for TDM of antifungal agents, summarize their pharmacokinetic and pharmacodynamic properties, identify treatment goals for efficacy and safety, and provide recommendations for optimal dosing and therapeutic monitoring strategies.Expert opinion: Several new antifungal agents are currently in development, including compounds from existing antifungal classes with enhanced pharmacokinetic or safety profiles as well as agents with novel targets for the treatment of IFIs. Given the predictable pharmacokinetics of these newly developed agents, use of routine TDM is not anticipated. However, expanded knowledge of exposure-response relationships of these compounds may yield a role for TDM to improve outcomes for adult and pediatric patients.

Evaluation of CYP2C19 Genotype-Guided Voriconazole Prophylaxis After Allogeneic Hematopoietic Cell Transplant

There is a high risk of voriconazole failure in those with subtherapeutic drug concentrations, which is more common in CYP2C19 (cytochrome P450 2C19) rapid/ultrarapid metabolizers (RMs/UMs). We evaluated CYP2C19 genotype-guided voriconazole dosing on drug concentrations and clinical outcomes in adult allogeneic hematopoietic cell transplant recipients. Poor (PMs), intermediate (IMs), and normal metabolizers (NMs) received voriconazole 200 mg twice daily; RMs/UMs received 300 mg twice daily. Steady-state trough concentrations were obtained after 5 days, targeting 1.0-5.5 mg/L. Of 89 evaluable patients, 29% had subtherapeutic concentrations compared with 50% in historical controls (P < 0.001). Zero, 26%, 50%, and 16% of PMs, IMs, NMs, and RMs/UMs were subtherapeutic. Voriconazole success rate was 78% compared with 54% in historical controls (P < 0.001). No patients experienced an invasive fungal infection (IFI). Genotype-guided dosing resulted in $4,700 estimated per patient savings as compared with simulated controls. CYP2C19 genotype-guided voriconazole dosing reduced subtherapeutic drug concentrations and effectively prevented IFIs.

Candida infections in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the American Society of Transplantation Infectious Diseases Community of Practice provide recommendations for the diagnosis and management of Candida infections in solid organ transplant recipients. Candida infections manifest primarily as candidemia and invasive candidiasis and cause considerable morbidity and mortality. Early diagnosis and initiation of treatment are necessary to reduce mortality. For both candidemia and invasive candidiasis, an echinocandin is recommended for initial therapy. However, early transition to oral therapy is encouraged when patients are stable and the organism is susceptible. Candida prophylaxis should be targeted for high-risk patients in liver, small bowel, and pancreas transplant recipients. Future research should address which patient groups may benefit most from preventative antifungal therapy strategies.

Posaconazole therapeutic drug monitoring in clinical practice and longitudinal analysis of the effect of routine laboratory measurements on posaconazole concentrations

Posaconazole is indicated for prophylaxis and treatment of invasive aspergillosis. Therapeutic drug monitoring (TDM) of posaconazole is used to optimise drug exposure. The aim of this study was to analyse and describe the TDM practices and exposure of posaconazole tablets. Patients who received posaconazole for treatment or prophylaxis of fungal infections were included in the study. The following therapeutic window was defined: if concentration was low (<0.7 mg/L for prophylaxis or < 1.5 mg/L for treatment) or high (>3.75 mg/L), the hospital pharmacist provided the physician with dosage advice, which implementation to patient care was analysed. A longitudinal analysis was performed to analyse if different confounding variables had an effect on posaconazole concentrations. Forty-seven patients were enrolled resulting in 217 posaconazole trough concentrations. A median of 3 (IQR 1-7) samples was measured per patient. The median concentration was 1.7 mg/L (IQR 0.8-2.7) for prophylaxis and 1.76 mg/L (IQR 1.3-2.3) for treatment. Overall, 78 posaconazole concentrations were out of the therapeutic window. For 45 (54%) of these concentrations, a dosage change was recommended. In the longitudinal analysis, the laboratory markers and patient baseline variables did not have an effect on posaconazole concentrations. Adequate posaconazole exposure was shown in 64% (affected 28 patients) of the measured concentrations. TDM practice of posaconazole can be improved by increasing the implementation rate of dose recommendation by a multidisciplinary antifungal stewardship team.

ESCMID-ECMM guideline: diagnosis and management of invasive aspergillosis in neonates and children

SCOPE

Presenting symptoms, distributions and patterns of diseases and vulnerability to invasive aspergillosis (IA) are similar between children and adults. However, differences exist in the epidemiology and underlying conditions, the usefulness of newer diagnostic tools, the pharmacology of antifungal agents and in the evidence from interventional phase 3 clinical trials. Therefore, the European Society for Clinical Microbiology and Infectious Diseases (ESCMID) and the European Confederation of Medical Mycology (ECMM) have developed a paediatric-specific guideline for the diagnosis and management of IA in neonates and children.

METHODS

Review and discussion of the scientific literature and grading of the available quality of evidence was performed by the paediatric subgroup of the ESCMID-ECMM-European Respiratory Society (ERS) Aspergillus disease guideline working group, which was assigned the mandate for the development of neonatal- and paediatric-specific recommendations.

QUESTIONS

Questions addressed by the guideline included the epidemiology of IA in neonates and children; which paediatric patients may benefit from antifungal prophylaxis; how to diagnose IA in neonates and children; which antifungal agents are available for use in neonates and children; which antifungal agents are suitable for prophylaxis and treatment of IA in neonates and children; what is the role of therapeutic drug monitoring of azole antifungals; and which management strategies are suitable to be used in paediatric patients. This guideline provides recommendations for the diagnosis, prevention and treatment of IA in the paediatric population, including neonates. The aim of this guideline is to facilitate optimal management of neonates and children at risk for or diagnosed with IA.

Invasive Aspergillosis in solid-organ transplant recipients: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated AST-IDCOP guidelines provide information on epidemiology, diagnosis, and management of Aspergillus after organ transplantation. Aspergillus is the most common invasive mold infection in solid-organ transplant (SOT) recipients, and it is the most common invasive fungal infection among lung transplant recipients. Time from transplant to diagnosis of invasive aspergillosis (IA) is variable, but most cases present within the first year post-transplant, with shortest time to onset among liver and heart transplant recipients. The overall 12-week mortality of IA in SOT exceeds 20%; prognosis is worse among those with central nervous system involvement or disseminated disease. Bronchoalveolar lavage galactomannan is preferred for the diagnosis of IA in lung and non-lung transplant recipients, in combination with other diagnostic modalities (eg, chest CT scan, culture). Voriconazole remains the drug of choice to treat IA, with isavuconazole and lipid formulations of amphotericin B regarded as alternative agents. The role of combination antifungals for primary therapy of IA remains controversial. Either universal prophylaxis or preemptive therapy is recommended in lung transplant recipients, whereas targeted prophylaxis is favored in liver and heart transplant recipients. In these guidelines, we also discuss newer antifungals and diagnostic tests, antifungal susceptibility testing, and special patient populations.

Current Concepts and Future Directions in the Pharmacology and Treatment of Coccidioidomycosis

Coccidioidomycosis remains a significant clinical problem with substantial morbidity and mortality. The vast majority of infections are asymptomatic and the need for early primary therapy remains controversial. The use of triazole antifungals has improved tolerability of therapy but concerns about acute and long-term toxicities among available agents limit their use. In addition, recent findings of decreased in vitro fluconazole susceptibility to as many as 37% of Coccidioides spp. isolates raises concerns regarding optimal therapy for these infections as fluconazole is commonly used for therapy including central nervous system disease. Thus, new agents from novel antifungal classes are currently in preclinical and clinical development aimed at reducing toxicity and improving outcomes of these serious infections.

Clinical mycology in Latin America and the Caribbean: A snapshot of diagnostic and therapeutic capabilities

Despite the existence of endemic mycoses in Latin America and the Caribbean, in addition to a large population of patients at risk for invasive mycoses, the capability of medical centres to perform a proper diagnosis in mycology has not been studied in the region. Moreover, availability of antifungal drugs in the region is unknown. Here, we report the results of a survey involving 129 centres in 24 countries. Only 9% of centres would have the potential to apply for the minimum standards in mycology, as determined by the European Confederation of Medical Mycology. There is an urgent need to improve diagnostic conditions in Latin America and the Caribbean, as well as providing access to safer and more efficacious antifungal drugs.

A pharmacokinetic model for voriconazole in a highly diversified population of children and adolescents with cancer

BACKGROUND

The wide pharmacokinetic variability of voriconazole leads to uncertainty regarding adequate exposure.

OBJECTIVES

To create a pharmacokinetic model that could help to explain the variability.

METHODS

Retrospective review of paediatric patients with cancer. Models were built using Pmetrics.

RESULTS

We analysed 158 trough measurements in 55 patients; in 41.8%, the serum levels were between 1 and 6 mg/L on initial measurement. After the measurements, dosage adjustments were made in 42 (76.3%) patients, and the percentage of adequate levels rose to 54.5%. Fourteen deaths (25.4%) were attributed to invasive fungal diseases. The mean serum levels were higher in deceased patients (mean ± SD: 3.1 ± 3.2 mg/L vs 2.5 ± 3.6 mg/L in survivors; P = 0.018), but the median doses per kg were higher in survivors. Drug exposure was also higher in deceased patients (mean ± SD of AUC: 19.2 ± 8.1 vs 9.5 ± 19.1 in survivors; P = 0.005). No correlation was found between serum concentrations <1 mg/L and death attributable to fungal disease. Bioavailability was estimated in 50%. The maximum velocity of clearance was reduced in deceased patients.

CONCLUSIONS

Extremely ill patients can be poor metabolizers of voriconazole. Therapeutic monitoring promotes only a limited improvement in drug management.

Invasive Aspergillosis in Pediatric Leukemia Patients: Prevention and Treatment

The purpose of this article is to review and update the strategies for prevention and treatment of invasive aspergillosis (IA) in pediatric patients with leukemia and in patients with hematopoietic stem cell transplantation. The major risk factors associated with IA will be described since their recognition constitutes the first step of prevention. The latter is further analyzed into chemoprophylaxis and non-pharmacologic approaches. Triazoles are the mainstay of anti-fungal prophylaxis while the other measures revolve around reducing exposure to mold spores. Three levels of treatment have been identified: (a) empiric, (b) pre-emptive, and (c) targeted treatment. Empiric is initiated in febrile neutropenic patients and uses mainly caspofungin and liposomal amphotericin B (LAMB). Pre-emptive is a diagnostic driven approach attempting to reduce unnecessary use of anti-fungals. Treatment targeted at proven or probable IA is age-dependent, with voriconazole and LAMB being the cornerstones in >2yrs and <2yrs age groups, respectively.

High voriconazole target-site exposure after approved sequence dosing due to nonlinear pharmacokinetics assessed by long-term microdialysis

Voriconazole, a broad-spectrum antifungal drug used to prevent and treat invasive fungal infections, shows complex pharmacokinetics and is primarily metabolised by various CYP enzymes. An adequate unbound antibiotic concentration-time profile at the target-site of an infection is crucial for effective prophylaxis or therapy success. Therefore, the aim was to evaluate the pharmacokinetics of voriconazole after the approved sequence dosing in healthy volunteers in interstitial space fluid, assessed by microdialysis, and in plasma. Moreover, potential pharmacogenetic influences of CYP2C19 polymorphisms on pharmacokinetics were investigated. The prospective, open-labelled, uncontrolled long-term microdialysis study included 9 healthy male individuals receiving the approved sequence dosing regimen for voriconazole. Unbound voriconazole concentrations were sampled over 84 h in interstitial space fluid of subcutaneous adipose tissue and in plasma and subsequently quantified via high-performance liquid chromatography. For pharmacokinetic data analysis, non-compartmental analysis was used. High interindividual variability in voriconazole concentration-time profiles was detected although dosing was adapted to body weight for the first intravenous administrations. Due to nonlinear pharmacokinetics, target-site exposure of voriconazole in healthy volunteers was found to be highly comparable to plasma exposure, particularly after multiple dosing. Regarding the CYP2C19 genotype-predicted phenotype, the individuals revealed a broad spectrum, ranging from poor to rapid metaboliser status. A strong relation between CYP2C19 genotype-predicted phenotype and voriconazole clearance was identified.

Advances in antifungal drug measurement by liquid chromatography-mass spectrometry

Fungal infections, especially invasive types, have become a serious healthcare problem as the immunocompromised population increases. There are five main classes of antifungal drugs: polyenes, flucytosine, allylamines, azoles, and echinocandins. Therapeutic drug monitoring (TDM) is justified for flucytosine and triazoles due to their large inter- and intra-individual pharmacokinetic variability and their high tendency for drug-drug interactions. Available methods for measuring these drugs include bioassay, liquid chromatography and liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The LC-MS/MS approach is preferred due to its superior analytic sensitivity and specificity. In this review, we highlight TDM methods by LC-MS/MS for these antifungal drugs searchable in PubMed by December 1, 2018. LC-MS/MS methods that were developed for other purposes such as pharmacokinetics or toxicokinetics were also included. We have critically analyzed these methods with an emphasis on sensitivity, specificity, simplicity, throughput and robustness.

Pre-Existing Liver Disease and Toxicity of Antifungals

Pre-existing liver disease in patients with invasive fungal infections further complicates their management. Altered pharmacokinetics and tolerance issues of antifungal drugs are important concerns. Adjustment of the dosage of antifungal agents in these cases can be challenging given that current evidence to guide decision-making is limited. This comprehensive review aims to evaluate the existing evidence related to antifungal treatment in individuals with liver dysfunction. This article also provides suggestions for dosage adjustment of antifungal drugs in patients with varying degrees of hepatic impairment, after accounting for established or emerging pharmacokinetic–pharmacodynamic relationships with regard to antifungal drug efficacy in vivo.

Are In Vitro Susceptibilities to Azole Antifungals Predictive of Clinical Outcome in the Treatment of Candidemia?

The purpose of this review is to critically analyze published data evaluating the impact of azole pharmacokinetic and pharmacodynamic parameters, MICs, and Candida species on clinical outcomes in patients with candidemia. Clinical breakpoints (CBPs) for fluconazole and voriconazole, which are used to determine susceptibility, have been defined by the Clinical and Laboratory Standards Institute (CLSI) for Candida species. Studies evaluating the relationship between treatment efficacy and in vitro susceptibility, as well as the pharmacodynamic targets, have been conducted in patients treated with fluconazole for candidemia; however, for species other than Candida albicans and Candida glabrata, and for other forms of invasive candidiasis, data remain limited and randomized trials are not available. Limited data evaluating these relationships with voriconazole are available. While pharmacodynamic targets for posaconazole and isavuconazole have been proposed based upon studies conducted in murine models, CBPs have not been established by CLSI. Fluconazole remains an important antifungal agent for the treatment of candidemia, and data supporting its use based on in vitro susceptibility are growing, particularly for C. albicans and C. glabrata Further investigation is needed to establish the roles of voriconazole, posaconazole, and isavuconazole in the treatment of candidemia and for all agents in the treatment of other forms of invasive candidiasis.

Posaconazole versus voriconazole as antifungal prophylaxis during induction therapy for acute myelogenous leukemia or myelodysplastic syndrome

OBJECTIVE

Patients with acute myelogenous leukemia or myelodysplastic syndrome undergoing induction chemotherapy are at increased risk of invasive fungal infection due to prolonged, severe neutropenia. Due to this risk, national guidelines recommend invasive fungal infection prophylaxis in this population until the resolution of neutropenia. Although posaconazole has demonstrated superiority over fluconazole and itraconazole, there is limited evidence for voriconazole for invasive fungal infection prophylaxis in this population. Even less data are available comparing posaconazole and voriconazole directly. The study objective was to investigate the efficacy and safety of delayed-release posaconazole tablets versus voriconazole for primary invasive fungal infection prophylaxis. The primary outcome was rate of discontinuation of either agent. Secondary outcomes included specific rates of discontinuation due to adverse events and drug-drug interactions, rates of breakthrough invasive fungal infection, and 30-day and 100-day mortality rates.

METHODS

This was a retrospective cohort study of adult patients admitted to NYU Langone Health between 1 January 2014 and 31 August 2017 and initiated on invasive fungal infection prophylaxis during induction or reinduction chemotherapy for acute myelogenous leukemia or myelodysplastic syndrome.

RESULTS

In total, 77 patients were included in the study: 43 using posaconazole delayed-release tablets and 34 using oral voriconazole. In the posaconazole group, 30% of patients (n = 13) discontinued therapy for any reason compared with 35% (n = 12) of patients in the voriconazole group (p = 0.64). A higher percentage of patients in the voriconazole group discontinued due to adverse events (6 patients, 18% vs. 1 patient, 2%, p = 0.04). Mortality rates at 30 and 100 days were similar between both groups. No breakthrough invasive fungal infections was noted in either group.

CONCLUSION

Overall, discontinuations for any reason were similar in patients taking both posaconazole delayed-release and oral voriconazole. Both posaconazole delayed-release tablets and oral voriconazole appear to be effective at preventing invasive fungal infection in acute myelogenous leukemia and myelodysplastic syndrome patients undergoing induction chemotherapy, although posaconazole may be more tolerable.

Is It Time for Systematic Voriconazole Pharmacogenomic Investigation for Central Nervous System Aspergillosis?

Voriconazole is the standard treatment for invasive aspergillosis but requires therapeutic drug monitoring to optimize therapy. We report two cases of central nervous system aspergillosis treated with voriconazole. Because of low trough plasma concentrations, we identified gain-of-function mutations in CYP2C19 that were partially responsible for the therapeutic failure of voriconazole. We suggest that systematic voriconazole pharmacogenomic investigation of cerebral aspergillosis be performed to avoid effective therapy delay in this life-threatening disease.

Population pharmacokinetics of voriconazole and CYP2C19 polymorphisms for optimizing dosing regimens in renal transplant recipients

AIMS

The aims of the present study were to characterize the pharmacokinetics of voriconazole in renal transplant recipients and to identify factors significantly affecting pharmacokinetic parameters. We also aimed to explore the optimal dosing regimens for patients who developed invasive fungal infections.

METHODS

A total of 105 patients (342 concentrations) were included prospectively in a population pharmacokinetic analysis. Nonlinear mixed-effects models were developed using Phoenix NLME software. Dosing simulations were performed based on the final model.

RESULTS

A one-compartment model with first-order absorption and elimination was used to characterize voriconazole pharmacokinetics. Population estimates of clearance, volume of distribution and oral bioavailability were 2.88 l·h-1 , 169.3 l and 58%, respectively. The allele frequencies of cytochrome P450 gene (CYP) 2C19*2, *3 and *17 variants were 29.2%, 5.2% and 0.5%, respectively. CYP2C19 genotype had a significant effect on the clearance. Voriconazole trough concentrations in poor metabolizers were significantly higher than in intermediate metabolizers and extensive metabolizers alike. The volume of distribution increased with increased body weight. The oral bioavailability was substantially lower within 1 month after transplantation but increased with postoperative time. Dosing simulations indicated that during the early postoperative period, poor metabolizers could be treated with 150 mg intravenously or 250 mg orally twice daily; intermediate metabolizers with 200 mg intravenously or 350 mg orally twice daily; and extensive metabolizers with 300 mg intravenously twice daily.

CONCLUSIONS

Using a combination of CYP2C19 genotype and postoperative time to determine the initial voriconazole dosing regimens followed by therapeutic drug monitoring could help to advance individualized treatment in renal transplantation patients with invasive fungal infections.

Therapeutic drug monitoring and safety of voriconazole therapy in patients with Child-Pugh class B and C cirrhosis: A multicenter study

OBJECTIVES

The purpose of this study was to investigate the pharmacokinetic profile and safety of voriconazole treatment in patients with Child-Pugh class B and C cirrhosis.

METHODS

Liver cirrhosis patients who had received the recommended voriconazole maintenance dose (group A) or halved maintenance dose (group B), orally or intravenously, were included. Voriconazole-related adverse events (AEs) were defined according to the Common Terminology Criteria for Adverse Events.

RESULTS

A total of 110 trough plasma concentrations of voriconazole (C_min) were measured in 78 patients. There was a significant difference in voriconazole C_min between group A and group B (C_min, 6.95±3.42mg/l vs. 4.02±2.00mg/l; p<0.001). No significant difference in voriconazole C_min between Child-Pugh class B and C cirrhosis patients was observed in either of the two groups. The international normalized ratio and co-medication with a CYP2C19 inhibitor had a significant effect on voriconazole C_min in group B. The incidence of AEs in group A was 26.5% and in group B was 15.9%, and 87.5% of AEs developed within 7days after starting voriconazole treatment.

CONCLUSIONS

These results suggest that the recommended dose and halved maintenance dose may be inappropriate in patients with Child-Pugh class B and C cirrhosis due to the high C_min, and that voriconazole C_min should be monitored earlier to avoid AEs.

Utility of posaconazole therapeutic drug monitoring and assessment of plasma concentration threshold for effective prophylaxis of invasive fungal infections: a meta-analysis with trial sequential analysis

Background

Posaconazole therapeutic drug monitoring (TDM) is increasingly used in clinical practice. However, the utility of posaconazole TDM and the target of posaconazole plasma concentration for clinical successful prophylaxis remain uncertain and controversial. The aim of this study was to evaluate posaconazole exposure-response relationship and determine an optimum posaconazole concentration for prophylaxis against invasive fungal infections (IFIs).

Methods

Bibliographic databases were searched (from inception to September 2017) to select studies including the clinical outcomes below and above concentration cut-off value of 0.5 mg/L and 0.7 mg/L. The reliability of the results were evaluated with trial sequential analysis (TSA).

Results

Twenty-eight studies with 1930 patients included were analyzed. The results of our pooled analysis demonstrated that patients with posaconazole plasma concentrations over 0.5 mg/L were twice more likely to achieve successful responses compared with those with lower concentrations (odds ratio, OR = 1.98, 95% confidence interval, CI 1.09–3.58, P = 0.02) while the threshold, 0.7 mg/L showed no significant difference (OR = 1.84, 95% CI 0.94–3.63, P = 0.08). The TSA results showed that there was sufficient information to support these findings.

Conclusions

An optimal posaconazole concentration target of 0.5 mg/L is suggested to ensure the clinical prophylactic efficacy and may help reduce the dosage and dose-dependent toxicity comparing with the target of 0.7 mg/L.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3055-3) contains supplementary material, which is available to authorized users.

[CYP2C19 genetic polymorphism and monitoring voriconazole plasma concentrations in the treatment and prevention of invasive fungal disease for hematological patients]

Objective: To evaluate the effects of CYP2C19 genetic polymorphism on the plasma concentration of voriconazole in patients with hematological disease and the value of serial monitoring plasma concentrations in the treatment and prevention of invasive fungal disease (IFD). Methods: From January 2016 to December 2016, 65 hematological patients who received voriconazole intravenous administration for the treatment of invasive fungal disease were enrolled in this study. The population CYP2C19 polymorphism of voriconazole were performed using PCR-Pyrosequencing. The trough plasma concentrations of vriconazole (Ctrough) was detected by ultra performance liquid chromatography tandem mass spectrometry. Results: Based on the genotype analysis, 65 subjects were identified as extensive metabolizers' group (30 cases) and poor metabolizers' group (35 cases). The Ctrough of the 65 patients were detected for 169 times totally, and there was a significant difference of Ctrough values between the two groups [0.98(0.38-2.08) mg/L vs 2.19(1.53-4.27) mg/L, z=10.286, P<0.001]. The medium of Ctrough in 65 hematological patients were described. Lack of response to therapy was more frequent in patients with voriconazole levels <1.5 mg/L (50.0%) than in those with voriconazole levels >1.5 mg/L (20.5%) (P=0.052). And the risk of adverse events was more frequent in patients with voriconazole levels >5.5 mg/L (80.0%) than in those with voriconazole levels ≤5.5 mg/L (8.3%) (χ2=11.689, P=0.020). Conclusion: Patients with CYP2C19 wild-type phenotype are extensive metabolizers, their Ctrough of voriconazole are significantly lower than patients with CYP2C19 non-wild-type phenotype (poor metabolizers). Appropriate concentrations of vriconazole can improve the efficacy and safety during treatment.

Pharmacokinetic Modeling of Voriconazole To Develop an Alternative Dosing Regimen in Children

The pharmacokinetic variability of voriconazole (VCZ) in immunocompromised children is high, and adequate exposure, particularly in the first days of therapy, is uncertain. A population pharmacokinetic model was developed to explore VCZ exposure in plasma after alternative dosing regimens. Concentration data were obtained from a pediatric phase II study. Nonlinear mixed effects modeling was used to develop the model. Monte Carlo simulations were performed to test an array of three-times-daily (TID) intravenous dosing regimens in children 2 to 12 years of age. A two-compartment model with first-order absorption, nonlinear Michaelis-Menten elimination, and allometric scaling best described the data (maximal kinetic velocity for nonlinear Michaelis-Menten clearance [V_max] = 51.5 mg/h/70 kg, central volume of distribution [V₁] = 228 liters/70 kg, intercompartmental clearance [Q] = 21.9 liters/h/70 kg, peripheral volume of distribution [V₂] = 1,430 liters/70 kg, bioavailability [F] = 59.4%, K_m = fixed value of 1.15 mg/liter, absorption rate constant = fixed value of 1.19 h^-1). Interindividual variabilities for V_max, V₁, Q, and F were 63.6%, 45.4%, 67%, and 1.34% on a logit scale, respectively, and residual variability was 37.8% (proportional error) and 0.0049 mg/liter (additive error). Monte Carlo simulations of a regimen of 9 mg/kg of body weight TID simulated for 24, 48, and 72 h followed by 8 mg/kg two times daily (BID) resulted in improved early target attainment relative to that with the currently recommended BID dosing regimen but no increased rate of accumulation thereafter. Pharmacokinetic modeling suggests that intravenous TID dosing at 9 mg/kg per dose for up to 3 days may result in a substantially higher percentage of children 2 to 12 years of age with adequate exposure to VCZ early during treatment. Before implementation of this regimen in patients, however, validation of exposure, safety, and tolerability in a carefully designed clinical trial would be needed.

Impact of the CYP2C19 genotype on voriconazole exposure in adults with invasive fungal infections

OBJECTIVES

Voriconazole, a first-line agent for the treatment of invasive fungal infections (IFIs), is metabolized by CYP2C19. A significant proportion of patients fail to achieve therapeutic trough concentrations with standard weight-based voriconazole dosing, placing them at increased risk for treatment failure, which can be life threatening. We sought to test the association between the CYP2C19 genotype and subtherapeutic voriconazole concentrations in adults with IFIs.

PATIENT AND METHODS

Adults receiving weight-based voriconazole dosing for the treatment of IFIs were genotyped for the CYP2C19*2, *3, and *17 polymorphisms, and CYP2C19 metabolizer phenotypes were inferred. Steady-state voriconazole trough plasma concentrations and the prevalence of subtherapeutic troughs (<2 mg/l) were compared between patients with the CYP2C19*17/*17 (ultrarapid metabolizer, UM) or *1/*17 (rapid metabolizer, RM) genotype versus those with other genotypes. Logistic regression, adjusting for clinical factors, was performed to estimate the odds of subtherapeutic concentrations.

RESULTS

Of 70 patients included (mean age 52.5±18 years), 39% were RMs or UMs. Compared with patients with the other phenotypes, RMs/UMs had a lower steady-state trough concentration (4.26±2.2 vs. 2.86±2.3, P=0.0093) and a higher prevalence of subtherapeutic troughs (16 vs. 52%, P=0.0028), with an odds ratio of 5.6 (95% confidence interval: 1.64-19.24, P=0.0044).

CONCLUSION

Our findings indicate that adults with the CYP2C19 RM or UM phenotype are more likely to have subtherapeutic concentrations with weight-based voriconazole dosing. These results corroborate previous findings in children and support the potential clinical utility of CYP2C19 genotype-guided voriconazole dosing to avoid underexposure in RMs and UMs.

Voriconazole and posaconazole therapeutic drug monitoring: a retrospective study

Background

Therapeutic drug monitoring (TDM) aims to minimize the clinical impact of posaconazole and voriconazole pharmacokinetic variability. However, its benefits on clinical outcomes are still being defined. Additionally, TDM data are limited for posaconazole IV and delayed-release tablet formulations among specific patient populations, including critically ill. The aim of this study was to determine the percentage of therapeutic posaconazole and voriconazole drug levels across all formulations in a real-world clinical setting and elucidate factors affecting attainment of target concentrations.

Methods

This study was a retrospective cohort study conducted at the University of Colorado Hospital between September 2006 and June 2015 that evaluated patients who received posaconazole or voriconazole TDM as part of routine care.

Results

Voriconazole (n = 250) and posaconazole (n = 100) levels were analyzed from 151 patients. Of these, 54% of voriconazole and 69% of posaconazole levels were therapeutic. For posaconazole, 14/38 (37%), 28/29 (97%) and 27/33 (82%) levels were therapeutic for the oral suspension, IV, and delayed-release tablet, respectively. Intravenous and delayed-release tablet posaconazole were 20 fold (p < 0.01) and sevenfold (p = 0.002) more likely than the oral suspension to achieve a therapeutic level. Subsequent levels were more likely to be therapeutic after dose adjustments (OR 3.31; 95% CI 1.3–8.6; p = 0.02), regardless of timing of initial non-therapeutic level. In a multivariable logistic regression analysis, no characteristics were independently predictive of therapeutic voriconazole levels and only absence of H2RA/PPI use was independently predictive of therapeutic posaconazole levels. There was no correlation between survival and therapeutic drug levels for either voriconazole (p = 0.67) or posaconazole (p = 0.50).

Conclusions

A high percentage of drug levels did not achieve TDM targets for voriconazole and posaconazole oral suspension, supporting the need for routine TDM for those formulations. The utility of TDM for the IV and delayed-release tablet formulations of posaconazole is less apparent.

Therapeutic drug monitoring for invasive mould infections and disease: pharmacokinetic and pharmacodynamic considerations

Therapeutic drug monitoring (TDM) may be required to achieve optimal clinical outcomes in the setting of significant pharmacokinetic variability, a situation that applies to a number of anti-mould therapies. The majority of patients receiving itraconazole should routinely be managed with TDM. Voriconazole exhibits highly variable inter-individual pharmacokinetics, and a trough concentration of 1.0-5.5 mg/L is widely accepted although it is derived from relatively low-quality evidence. The case for TDM of posaconazole is currently in a state of flux following the introduction of a newer tablet formulation with improved oral bioavailability, but it may be indicated when used for either prophylaxis or treatment of established disease. The novel broad-spectrum azole drug isavuconazole does not currently appear to require TDM but 'real-world' data are awaited and TDM could be considered in selected clinical cases. For both polyene and echinocandin agents, there are insufficient data regarding the relationship between serum concentrations and therapeutic outcomes to support the routine use of TDM. A number of practical challenges to the implementation of TDM in the treatment of invasive mould infections remain unsolved. The delivery of TDM as a future standard of care will require real-time measurement of drug concentrations at the bedside and algorithms for dosage adjustment. Finally, measures of pharmacodynamic effect are required to deliver therapy that is truly individualized.

Voriconazole-induced QT prolongation among hemato-oncologic patients: clinical characteristics and risk factors

PURPOSE

The purpose of this study is to determine the rate of QTcP and associated risk factors in patients treated with voriconazole.

METHODS

We conducted a retrospective chart review of all patients treated with voriconazole in a large tertiary center between 2009 and 2015, using paired comparison of QTc intervals on and off voriconazole treatment, adjusted for comorbidities, electrolyte abnormalities, and concurrent medications.

RESULTS

Fifty-four patients were included, of whom 53 were diagnosed with oncologic/hemato-oncologic disease. Mean QTc during voriconazole therapy (448.0 ± 52.9 msec) was significantly longer compared to QTc off voriconazole (421.8 ± 42.2 msec; p = 0.002). QTcP ≥30 msec and ≥60 msec was demonstrated in 43% (23 patients) and 28% (15 patients), respectively. Multivariate analysis showed that QTcP was significantly associated with baseline QTc ≥ 450 msec (upper QTc quartile) (p < 0.01) and low serum potassium levels (p < 0.01). Contrarily, no significant association was found between mean voriconazole daily and cumulative dose and QTcP.

CONCLUSION

Our findings indicate that hemato-oncologic patients treated with voriconazole are at increased risk for QTcP, especially in the presence of baseline QTc ≥ 450 msec and low serum potassium levels.

New facets of antifungal therapy

Invasive fungal infections remain a major cause of morbidity and mortality in immunocompromised patients, and such infections are a substantial burden to healthcare systems around the world. However, the clinically available armamentarium for invasive fungal diseases is limited to 3 main classes (i.e., polyenes, triazoles, and echinocandins), and each has defined limitations related to spectrum of activity, development of resistance, and toxicity. Further, current antifungal therapies are hampered by limited clinical efficacy, high rates of toxicity, and significant variability in pharmacokinetic properties. New antifungal agents, new formulations, and novel combination regimens may improve the care of patients in the future by providing improved strategies to combat challenges associated with currently available antifungal agents. Likewise, therapeutic drug monitoring may be helpful, but its present use remains controversial due to the lack of available data. This article discusses new facets of antifungal therapy with a focus on new antifungal formulations and the synergistic effects between drugs used in combination therapy.

Development of a liquid chromatography tandem mass spectrometry method for the simultaneous measurement of voriconazole, posaconazole and itraconazole

Background Azole-based antifungals are the first-line therapy for some of the most common mycoses and are now also being used prophylactically to protect immunocompromised patients. However, due to variability in both their metabolism and bioavailability, therapeutic drug monitoring is essential to avoid toxicity but still gain maximum efficacy. Methods Following protein precipitation of serum with acetonitrile, 20  µL of extract was injected onto a 2.1 × 50 mm Waters Atlantis dC18 3  µm column. Detection was via a Waters Quattro Premier XE tandem mass spectrometer operating in ESI-positive mode. Multiple reaction monitoring (MRM) detected two product ions for each compound and one for each isotopically labelled internal standard. Ion suppression, linearity, stability, matrix effects, recovery, imprecision, lower limits of measuring interval and detection were all assessed. Results Optimal chromatographic separation was achieved using gradient elution over 8 minutes. Voriconazole, posaconazole and itraconazole eluted at 1.71, 2.73 and 3.41 min, respectively. The lower limits of measuring interval for all three compounds was 0.1 mg/L. The assay was linear to 10 mg/L for voriconazole (R²= 0.995) and 5 mg/L for posaconazole (R²= 0.990) and itraconazole (R²= 0.991). The assay was both highly accurate and precise with % bias of voriconazole, posaconazole and itraconazole, respectively, when compared with previous NEQAS samples. The intra-assay precision (CV%) was 1.6%, 2.5% and 1.9% for voriconazole, posaconazole and itraconazole, respectively, across the linear range. Conclusion A simple and robust method has been validated for azole antifungal therapeutic drug monitoring. This new assay will result in a greatly improved sample turnaround time and will therefore vastly increase the clinical utility of azole antifungal drug monitoring.

Clinical hepatotoxicity associated with antifungal agents

INTRODUCTION

Invasive fungal diseases (IFDs) are a leading cause of morbidity and mortality among immunocompromised patients with bone marrow failure syndromes, hematological malignancies, hematopoietic stem cell transplantation (HSCT), those admitted in intensive care units (ICUs) and those with prolonged febrile neutropenia. IFDs occur in a setting of multiple morbidities and are associated with case fatality rates between 30 and 70%. Along with the development of classes and compounds, the last two decades have seen substantial improvements in the prevention and management of these infections and an overall increased use of antifungal agents. Areas covered: All antifungal agents, including amphotericin B formulations, echinocandins and the triazoles, may cause hepatic toxicity that ranges from mild and asymptomatic abnormalities in liver function tests to substantial liver injury and fulminant hepatic failure. Expert opinion: The present article reviews incidence and severity of hepatotoxicity associated with different classes and agents to provide a better understanding of this specific end organ toxicity and safer use of antifungal agents A thorough understanding of the distribution, metabolism, elimination and drug-drug interactions of antifungal agents used for management of IFDs in combination with safety data from clinical trials, pharmacokinetic and pharmacodynamic studies may guide the use of antifungal treatment in patients at high risk for the development of hepatic dysfunction and in those with underlying liver damage due to cytotoxic therapy.

Isavuconazole for the treatment of invasive aspergillosis and mucormycosis: current evidence, safety, efficacy, and clinical recommendations

The majority of invasive mold infections diagnosed in immunocompromised cancer patients include invasive aspergillosis (IA) and mucormycosis. Despite timely and effective therapy, mortality remains considerable. Antifungal agents currently available for the management of these serious infections include triazoles, polyenes, and echinocandins. Until recently, posaconazole has been the only triazole with a broad spectrum of anti-mold activity against both Aspergillus sp. and mucorales. Other clinically available triazoles voriconazole and itraconazole, with poor activity against mucorales, have significant drug interactions in addition to a side effect profile inherent for all triazoles. Polyenes including lipid formulations pose a problem with infusion-related side effects, electrolyte imbalance, and nephrotoxicity. Echinocandins are ineffective against mucorales and are approved as salvage therapy for refractory IA. Given that all available antifungal agents have limitations, there has been an unmet need for a broad-spectrum anti-mold agent with a favorable profile. Following phase III clinical trials that started in 2006, isavuconazole (ISZ) seems to fit this profile. It is the first novel triazole agent recently approved by the United States Food and Drug Administration (FDA) for the treatment of both IA and mucormycosis. This review provides a brief overview of the salient features of ISZ, its favorable profile with regard to spectrum of antifungal activity, pharmacokinetic and pharmacodynamic parameters, drug interactions and tolerability, clinical efficacy, and side effects.

Experiment design for nonparametric models based on minimizing Bayes Risk: application to voriconazole¹

An experimental design approach is presented for individualized therapy in the special case where the prior information is specified by a nonparametric (NP) population model. Here, a NP model refers to a discrete probability model characterized by a finite set of support points and their associated weights. An important question arises as to how to best design experiments for this type of model. Many experimental design methods are based on Fisher information or other approaches originally developed for parametric models. While such approaches have been used with some success across various applications, it is interesting to note that they largely fail to address the fundamentally discrete nature of the NP model. Specifically, the problem of identifying an individual from a NP prior is more naturally treated as a problem of classification, i.e., to find a support point that best matches the patient's behavior. This paper studies the discrete nature of the NP experiment design problem from a classification point of view. Several new insights are provided including the use of Bayes Risk as an information measure, and new alternative methods for experiment design. One particular method, denoted as MMopt (multiple-model optimal), will be examined in detail and shown to require minimal computation while having distinct advantages compared to existing approaches. Several simulated examples, including a case study involving oral voriconazole in children, are given to demonstrate the usefulness of MMopt in pharmacokinetics applications.

Pediatric Invasive Aspergillosis

Invasive aspergillosis (IA) is a disease of increasing importance in pediatrics due to growth of the immunocompromised populations at risk and improvements in long-term survival for many of these groups. While general principles of diagnosis and therapy apply similarly across the age spectrum, there are unique considerations for clinicians who care for children and adolescents with IA. This review will highlight important differences in the epidemiology, clinical manifestations, diagnosis, and therapy of pediatric IA.

Allergic Bronchopulmonary Aspergillosis

Allergic bronchopulmonary aspergillosis (ABPA), a progressive fungal allergic lung disease, is a common complication of asthma or cystic fibrosis. Although ABPA has been recognized since the 1950s, recent research has underscored the importance of Th2 immune deviation and granulocyte activation in its pathogenesis. There is also strong evidence of widespread under-diagnosis due to the complexity and lack of standardization of diagnostic criteria. Treatment has long focused on downregulation of the inflammatory response with prolonged courses of oral glucocorticosteroids, but more recently concerns with steroid toxicity and availability of new treatment modalities has led to trials of oral azoles, inhaled amphotericin, pulse intravenous steroids, and subcutaneously-injected anti-IgE monoclonal antibody omalizumab, all of which show evidence of efficacy and reduced toxicity.