Prevention of Invasive Aspergillus Fungal Infections with the Suspension and Delayed-Release Tablet Formulations of Posaconazole in Patients with Haematologic Malignancies

Evaluation of Posaconazole Serum Concentrations Achieved With Delayed-release Tablets and Oral Suspension in Patients Undergoing Intensive Chemotherapy for Acute Myeloid Leukemia and Myelodysplastic Syndrome

Data on posaconazole serum levels of patients on prophylaxis with delayed-release tablets or oral suspension during intensive chemotherapy for acute myeloid leukemia and myelodysplastic syndrome are scarce. In this analysis, the proportion of patients with acute myeloid leukemia/myelodysplastic syndrome achieving posaconazole target concentrations with delayed-release tablets was higher than with oral suspension.

Invasive Pulmonary Aspergillosis

Invasive pulmonary aspergillosis is growing in incidence, as patients at risk are growing in diversity. Outside the classical context of neutropenia, new risk factors are emerging or newly identified, such as new anticancer drugs, viral pneumonias and hepatic dysfunctions. Clinical signs remain unspecific in these populations and the diagnostic work-up has considerably expanded. Computed tomography is key to assess the pulmonary lesions of aspergillosis, whose various features must be acknowledged. Positron-emission tomography can bring additional information for diagnosis and follow-up. The mycological argument for diagnosis is rarely fully conclusive, as biopsy from a sterile site is challenging in most clinical contexts. In patients with a risk and suggestive radiological findings, probable invasive aspergillosis is diagnosed through blood and bronchoalveolar lavage fluid samples by detecting galactomannan or DNA, or by direct microscopy and culture for the latter. Diagnosis is considered possible with mold infection in lack of mycological criterion. Nevertheless, the therapeutic decision should not be hindered by these research-oriented categories, that have been completed by better adapted ones in specific settings. Survival has been improved over the past decades with the development of relevant antifungals, including lipid formulations of amphotericin B and new azoles. New antifungals, including first-in-class molecules, are awaited.

Subtherapeutic concentrations of posaconazole tablet: determining risk factors and effectiveness of a standardized dose adjustment in hematology inpatients

Posaconazole is indicated for antifungal prophylaxis in hematology patients at high-risk of invasive fungal infections (IFI). Consensus guidelines recommend maintaining steady-state trough concentrations above 0.7 mg/L; however, upto one-third of patients return subtherapeutic concentrations which is associated with breakthrough IFI. This retrospective observational study of 496 concentrations from 90 hematology inpatients prescribed posaconazole tablet (PCZ-tab) between May 2017 and May 2019 identified 24% (n = 121) of posaconazole concentrations were subtherapeutic after the dosage of 300 mg daily. On multivariable analyses, diarrhea (p = 0.002), male gender (p = 0.018), and concurrent regular metoclopramide (p = 0.002) were significantly associated with subtherapeutic posaconazole concentrations. Eighty-nine percent of patients (n = 16) who underwent dose adjustment to 200 mg twice daily successfully achieved target posaconazole concentrations at first steady-state measurement. This study confirms that therapeutic drug monitoring of posaconazole remains necessary as subtherapeutic posaconazole concentrations are relatively common, and that dose adjustment of 200 mg twice daily, safely enabled achievement of therapeutic concentrations.

Antifungal Drugs TDM: Trends and Update

PURPOSE

The increasing burden of invasive fungal infections results in growing challenges to antifungal (AF) therapeutic drug monitoring (TDM). This review aims to provide an overview of recent advances in AF TDM.

METHODS

We conducted a PubMed search for articles during 2016-2020 using "TDM" or "pharmacokinetics" or "drug-drug-interaction" with "antifungal," consolidated for each AF. Selection was limited to English language articles with human data on drug exposure.

RESULTS

More than 1000 articles matched the search terms. We selected 566 publications. The latest findings tend to confirm previous observations in real-life clinical settings. The pharmacokinetic variability related to special populations is not specific but must be considered. AF benefit-to-risk ratio, drug-drug interaction (DDI) profiles, and minimal inhibitory concentrations for pathogens must be known to manage at-risk situations and patients. Itraconazole has replaced ketoconazole in healthy volunteers DDI studies. Physiologically based pharmacokinetic modeling is widely used to assess metabolic azole DDI. AF prophylactic use was studied more for Aspergillus spp. and Mucorales in oncohematology and solid organ transplantation than for Candida (already studied). Emergence of central nervous system infection and severe infections in immunocompetent individuals both merit special attention. TDM is more challenging for azoles than amphotericin B and echinocandins. Fewer TDM requirements exist for fluconazole and isavuconazole (ISZ); however, ISZ is frequently used in clinical situations in which TDM is recommended. Voriconazole remains the most challenging of the AF, with toxicity limiting high-dose treatments. Moreover, alternative treatments (posaconazole tablets, ISZ) are now available.

CONCLUSIONS

TDM seems to be crucial for curative and/or long-term maintenance treatment in highly variable patients. TDM poses fewer cost issues than the drugs themselves or subsequent treatment issues. The integration of clinical pharmacology into multidisciplinary management is now increasingly seen as a part of patient care.

Evaluating posaconazole, its pharmacology, efficacy and safety for the prophylaxis and treatment of fungal infections

INTRODUCTION

Invasive fungal diseases (IFDs) are a significant cause of morbidity and mortality among immunocompromised patients. Safe and effective antifungal medications used for prophylaxis and treatment are pivotal in their management. Posaconazole is a promising triazole antifungal agent.

AREAS COVERED

The authors discuss the pharmacological properties of posaconazole, including pharmacokinetics/pharmacodynamics, safety and tolerability profile, together with efficacy data for prophylaxis and treatment as well as its use in special populations based on current literature.

EXPERT OPINION

Posaconazole has a favorable safety and tolerability profile; however, caution is advised when co-administered with agents that are CYP3A4 inhibitors, because their concentration may significantly increase, and their levels should be closely monitored. It has an extended spectrum of activity against yeasts and filamentous fungi. It is successfully used as prophylaxis for patients with acute myeloid leukemia (AML)/myelodysplastic syndrome (MDS) and post-hematopoietic cell transplantation (HCT) with graft-versus-host disease (GVHD). It is the first line treatment for oropharyngeal candidiasis and is also used as a salvage treatment for refractory IFDs. Currently available formulations include the oral suspension, delayed-release tablets and solution for intravenous infusion, all with different PK/PD properties and indications. Its use in children and adolescents is currently being examined in Phase-II clinical trials.

Reducing infectious complications after allogeneic stem cell transplant

INTRODUCTION

Infections remain a significant problem, in patients undergoing an allogeneic hematopoietic stem-cell transplant (HSCT) and efforts have been made over the years, to reduce the incidence, morbidity and mortality of infectious complications.

AREAS COVERED

This manuscript is focused on the epidemiology, risk factors and prevention of infections after allogeneic HSCT. A systematic literature review was performed using the PubMed database, between November 2019 and January 2020, with the following MeSH terms: stem-cell transplantation, infection, fungal, bacterial, viral, prophylaxis, vaccines, prevention. The authors reviewed all the publications, and following a common revision, a summary report was made and results were divided in three sections: bacterial, fungal and viral infections.

EXPERT OPINION

Different infections occur in the early, intermediate and late post-transplant period, due to distinct risk factors. Improved diagnostic techniques, pre-emtive therapy and better prophylaxis of immunologic complications, have reduced the morbidity and mortality of infections. The role of the gut microbiota is under careful scrutiny and may further help us to identify high-risk patients.

Pharmacokinetics and Safety of Posaconazole Tablet Formulation in Chinese Participants at High Risk for Invasive Fungal Infection

INTRODUCTION

This study characterized the multidose pharmacokinetic (PK) characteristics of posaconazole tablets used as prophylactic antifungal therapy in Chinese patients with acute myelogenous leukemia (AML) at risk for invasive fungal infection (IFI).

METHODS

Participants in this open-label, single-arm, phase 1b study received posaconazole 300 mg twice daily on day 1 and then once daily for up to 28 days. In the intensive PK sampling subgroup, posaconazole was administered under fasting conditions on days 1 and 8, and blood samples were regularly collected over 24 h. Trough PK sampling was conducted in all participants on days 1, 2, 3, 8, 14, 21, and 28 without regard for food intake. Population PK characteristics were predicted using PK modeling. Primary endpoints were steady-state average concentration (C_avg) and percentage of participants with steady-state C_avg (predicted and observed) > 500 ng/ml. Treatment safety and efficacy were secondary endpoints.

RESULTS

Sixty-five adult Chinese participants were enrolled. On day 8, steady-state arithmetic mean C_avg was 1610 ng/ml (% coefficient of variation [%CV] 42.8%) in the intensive PK subgroup (n = 20). All participants achieved a steady-state C_avg > 500 ng/ml. Predicted C_avg (pC_avg) was 1770 ng/ml (%CV 33.7%) in the total population (n = 64); 92.2% of participants had pC_avg values ≥ 500 ng/ml (n = 59). The posaconazole tablet safety profile was consistent with that of the oral formulation, and the IFI rate was 3%.

CONCLUSION

In Chinese AML patients, the posaconazole 300-mg tablet provided PK data comparable with those of previous studies and was generally well tolerated and efficacious.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT02387983.

Efficacy of Posaconazole Prophylaxis for Fungal Disease in Hematology Patients Treated With Chemotherapy and Transplantation: An Open-Label, Prospective, Observational Study

Background

Posaconazole (PCZ) is used prophylactically to prevent invasive fungal infections (IFIs) in patients with hematological malignancies.

Objective

To evaluate the cut-off serum concentration of PCZ for successful IFI prophylaxis in Chinese subjects.

Patients and Methods

A total of 74 patients treated with induction chemotherapy (n = 10) and allogeneic hematopoietic stem cell transplantation (HSCT) (n = 64), who received PCZ prophylactically as an oral suspension for >7 days, were included in the study. Clinical, radiological, microbiological culture results, and treatment responses were analyzed and drug concentration assays performed.

Results

The overall incidence of possible, probable, and proven IFIs was 13.5% (10/74), with five patients in the chemotherapy group and five in the HSCT group. The PCZ serum concentration in most patients (54/63) was in the range of 0.25–1.0 μg/ml, and this concentration range was significantly associated with the success rate of PCZ prophylaxis. A cut-off value of 0.47 μg/ml can be considered as an evaluation index for PCZ prophylaxis. Taking a proton pump inhibitor (PPI) would reduce the PCZ blood concentration, but not affect the IFD breakthrough point. PCZ treatment for hematopoietic malignancy or HSCT patients with a serum concentration of PCZ < 0.47 μg/ml were risk factors for PCZ prophylaxis of IFIs, determined by univariable and multivariable regression analyses.

Conclusion

The serum concentration of PCZ was related to the incidence of IFIs and a serum concentration of >0.47 μg/ml is highly recommended to avoid IFIs after chemotherapy or HSCT.

Clinical Trial Registration

Chinese Clinical Trial Registry: ChiCTR1900026294.

Treatment by Posaconazole Tablets, Compared to Posaconazole Suspension, Does Not Reduce Variability of Posaconazole Trough Concentrations

The delayed-release tablet formulation of posaconazole (POS-tab) results in higher plasma POS trough concentrations (C_min) than the oral suspension (POS-susp), which raises the question of the utility of therapeutic drug monitoring (TDM). We aimed to compare the variability of the POS C_min for the two formulations and identify determinants of the POS-tab C_min and its variability. Demographic, biological, and clinical data from 77 allogeneic hematopoietic stem cell transplant patients (874 C_min) treated with POS-tab (n = 41), POS-susp (n = 29), or both (n = 7) from January 2015 to December 2016 were collected retrospectively. Interpatient and within-subject coefficients of variation (CVs) of the C_min adjusted to dose (D) were calculated for each formulation. Between-group comparisons were performed using a linear mixed effects model. The POS C_min was higher for the tablet than for the suspension (median [25th-75th percentile]: 1.8 [1.2-2.4] mg/liter versus 1.2 [0.7-1.6] mg/liter, P < 0.0001). Interpatient CVs for the tablet and suspension were 60.8 versus 63.5% (P = 0.7), whereas within-subject CVs were 39.7 and 44.9%, respectively (P = 0.3). Univariate analysis showed that age and treatment by POS-tab were significantly and positively associated with the POS C_min, whereas diarrhea was associated with a diminished POS C_min Multivariate analysis identified treatment with POS-tab and diarrhea as independent factors of the POS C_min, with a trend toward a lower impact of diarrhea during treatment with POS-tab (P = 0.07). Despite increased POS exposure with the tablet formulation, the variability of the POS C_min was not significantly lower than that of the suspension. This suggests that TDM may still be useful to optimize tablet POS therapy.

Clinical Pharmacokinetics of Second-Generation Triazoles for the Treatment of Invasive Aspergillosis and Candidiasis

Second-generation triazoles were developed in response to the quest for more efficacious and safer therapeutic options for the treatment of severe systemic aspergillosis and candidiasis. These agents include voriconazole, posaconazole, isavuconazole, and ravuconazole. The aim of this review was to present and compare the pharmacokinetic characteristics of second-generation triazoles for the treatment of invasive aspergillosis and candidiasis, emphasizing their clinical implications. The MEDLINE, Scopus, EBSCO, Google Scholar, and SCIndeks databases were searched using advanced search options, including the names of second-generation triazoles and pharmacokinetic terms as keywords. The intravenous administration of voriconazole, posaconazole, and isavuconazole results in stable pharmacokinetics of these drugs, with mostly predictable variations influenced by common and usually known factors in routine clinical settings. The high oral bioavailability of isavuconazole and, to some extent, voriconazole makes them suitable for intravenous-to-oral switch strategies. Except for intravenous voriconazole (due to the accumulation of the toxic vehicle hydroxypropyl betadex), dose reduction of second-generation triazoles is not needed in patients with renal failure; patients with hepatic insufficiency require dose reduction only in advanced disease stages. The introduction of therapeutic drug monitoring could aid attempts to optimize the blood concentrations of triazoles and other drugs that are known to or that possibly interact, thus increasing treatment efficacy and safety. There is a need for new studies that are designed to provide useful data on second-generation triazole pharmacokinetics, particularly in special circumstances such as central nervous system and ocular infections, infections in newborns and infants, and in subjects with genetic polymorphisms of metabolizing enzymes.

Breakthrough Invasive Mold Infections in the Hematology Patient: Current Concepts and Future Directions

Although the widespread use of mold-active agents (especially the new generation of triazoles) has resulted in reductions of documented invasive mold infections (IMIs) in patients with hematological malignancies and allogeneic hematopoietic stem cell transplantation (HSCT), a subset of such patients still develop breakthrough IMIs (bIMIs). There are no data from prospective randomized clinical trials to guide therapeutic decisions in the different scenarios of bIMIs. In this viewpoint, we present the current status of our understanding of the clinical, diagnostic, and treatment challenges of bIMIs in high-risk adult patients with hematological cancer and/or HSCT receiving mold-active antifungals and outline common clinical scenarios. As a rule, managing bIMIs demands an individualized treatment plan that takes into account the host, including comorbidities, certainty of diagnosis and site of bIMIs, local epidemiology, considerations for fungal resistance, and antifungal pharmacological properties. Finally, we highlight areas that require future investigation in this complex area of clinical mycology.