Invasive fusariosis in patients with leukaemia in the era of mould-active azoles: increasing incidence, frequent breakthrough infections and lack of improved outcomes.

OBJECTIVES: Historically, patients with leukaemia and invasive fusariosis (IF) have experienced poor outcomes in the setting of persistent immunosuppression. Herein, we retrospectively reviewed the incidence, presentation and outcomes of IF that are scarcely studied in contemporary cohorts of leukaemia patients. METHODS: We identified adult leukaemia patients with proven or probable IF at MD Anderson Cancer Center during 2009-21. Independent risk factors for 42 day mortality after IF diagnosis were determined using a multivariable logistic regression model. Combined with historical data, the annual IF incidence density over the past 23 years was estimated using Poisson regression analysis. RESULTS: Among 140 leukaemia patients with IF (114 proven), 118 patients (84%) had relapsed/refractory leukaemia and 124 (89%) had neutropenia at IF diagnosis. One hundred patients (71%) had pulmonary IF, 88 (63%) had disseminated IF and 48 (34%) had fungaemia. Coinfections were common (55%). Eighty-nine patients (64%) had breakthrough IF to mould-active triazoles. Most patients (84%) received combination antifungal therapy. Neutrophil recovery [adjusted OR (aOR), 0.04; 95% CI, 0.01-0.14; P < 0.0001], pulmonary IF (aOR, 3.28; 95% CI, 1.11-9.70; P = 0.032) and high SOFA score (aOR, 1.91 per 1-point increase; 95% CI, 1.47-2.50; P < 0.0001) were independent predictors of 42 day mortality outcomes. From 1998 to 2021, IF incidence density increased significantly at an annual ratio of 1.03 (95% CI, 1.01-1.06; P = 0.04). CONCLUSIONS: IF is predominantly seen in patients with relapsed/refractory leukaemia and increasingly seen as a breakthrough infection to mould-active triazoles. Despite frequent combination antifungal therapy, high mortality rates have persisted in patients with lasting neutropenia.

Triazole antifungal drug interactions-practical considerations for excellent prescribing.

Systemic antifungal therapy is critical for reducing the mortality from many invasive and chronic fungal infections. Triazole antifungals are the most frequently prescribed antifungals but require attention to dosing and drug interactions. Nearly 600 severe drug-drug interactions and over 1100 moderate interactions requiring dose modifications are described or anticipated with systemic antifungal agents (see https://www.aspergillus.org.uk/antifungal-drug-interactions/). In this article, we address the common and less common, but serious, drug interactions observed in clinical practice with triazole antifungals, including a group of drugs that cannot be prescribed with all or most triazole antifungals (ivabradine, ranolazine, eplerenone, fentanyl, apomorphine, quetiapine, bedaquiline, rifampicin, rifabutin, sirolimus, phenytoin and carbamazepine). We highlight interactions with drugs used in children and new agents introduced for the treatment of haematological malignancies or graft versus host disease (midostaurin, ibrutinib, ruxolitinib and venetoclax). We also summarize the multiple interactions between oral and inhaled corticosteroids and triazole antifungals, and the strategies needed to optimize the therapeutic benefits of triazole antifungal therapy while minimizing potential harm to patients.

Radiology-based diagnosis of fungal pulmonary infections in high-risk hematology patients: are we making progress?

PURPOSE OF REVIEW: In patients with hematological malignancies, high-resolution computed tomography (CT) is the recommended imaging approach for diagnosis, staging and monitoring of invasive fungal disease (IFD) but lacks specificity. We examined the status of current imaging modalities for IFD and possibilities for more effective applications of current technology for improving the specificity of IFD diagnosis. RECENT FINDINGS: Although CT imaging recommendations for IFD are largely unchanged in the last 20 years, improvements in CT scanner technology and image processing algorithms now allow for technically adequate examinations at much lower radiation doses. CT pulmonary angiography can improve both the sensitivity and specificity of CT imaging for angioinvasive molds in both neutropenic and nonneutropenic patients, through detection of the vessel occlusion sign (VOS). MRI-based approaches also show promise not only for early detection of small nodules and alveolar hemorrhage but can also be used to detect pulmonary vascular occlusion without radiation and iodinated contrast media. 18F-fluorodeoxyglucose (FDG) PET/computed tomography (FDG-PET/CT) is increasingly used to monitor long-term treatment response for IFD, but could become a more powerful diagnostic tool with the development of fungal-specific antibody imaging tracers. SUMMARY: High-risk hematology patients have a considerable medical need for more sensitive and specific imaging approaches for IFD. This need may be addressable, in part, by better exploiting recent progress in CT/MRI imaging technology and algorithms to improve the specificity of radiological diagnosis for IFD.

Investigational Antifungal Agents for Invasive Mycoses: A Clinical Perspective.

Treatment of invasive fungal infections (IFIs) remains challenging, because of the limitations of the current antifungal agents (ie, mode of administration, toxicity, and drug-drug interactions) and the emergence of resistant fungal pathogens. Therefore, there is an urgent need to expand our antifungal armamentarium. Several compounds are reaching the stage of phase II or III clinical assessment. These include new drugs within the existing antifungal classes or displaying similar mechanism of activity with improved pharmacologic properties (rezafungin and ibrexafungerp) or first-in-class drugs with novel mechanisms of action (olorofim and fosmanogepix). Although critical information regarding the performance of these agents in heavily immunosuppressed patients is pending, they may provide useful additions to current therapies in some clinical scenarios, including IFIs caused by azole-resistant Aspergillus or multiresistant fungal pathogens (eg, Candida auris, Lomentospora prolificans). However, their limited activity against Mucorales and some other opportunistic molds (eg, some Fusarium spp.) persists as a major unmet need.

Quandaries of deciding when to change first-line therapy in invasive pulmonary aspergillosis.

We read the excellent viewpoint by Slavin et al. (J Antimicrob Chemother 2022; 77: 16-23) that draws upon the experience of an advisory board of notable experts to comprehensively address many of the clinical factors that drive the need for changes in antifungal therapy for invasive aspergillosis (IA). As noted by the authors, there remains a paucity of quality data to support many of the decisions faced by clinicians managing patients with IA. However, we would like to highlight several other important issues, not fully addressed in that viewpoint, that play an important role in deciding when to change antifungal therapy for IA.

Machine learning-assisted directed protein evolution with combinatorial libraries.

To reduce experimental effort associated with directed protein evolution and to explore the sequence space encoded by mutating multiple positions simultaneously, we incorporate machine learning into the directed evolution workflow. Combinatorial sequence space can be quite expensive to sample experimentally, but machine-learning models trained on tested variants provide a fast method for testing sequence space computationally. We validated this approach on a large published empirical fitness landscape for human GB1 binding protein, demonstrating that machine learning-guided directed evolution finds variants with higher fitness than those found by other directed evolution approaches. We then provide an example application in evolving an enzyme to produce each of the two possible product enantiomers (i.e., stereodivergence) of a new-to-nature carbene Si-H insertion reaction. The approach predicted libraries enriched in functional enzymes and fixed seven mutations in two rounds of evolution to identify variants for selective catalysis with 93% and 79% ee (enantiomeric excess). By greatly increasing throughput with in silico modeling, machine learning enhances the quality and diversity of sequence solutions for a protein engineering problem.

Navigating the Uncertainties of COVID-19-Associated Aspergillosis: A Comparison With Influenza-Associated Aspergillosis.

Invasive pulmonary aspergillosis (IPA) is increasingly recognized as a life-threatening superinfection of severe respiratory viral infections, such as influenza. The pandemic of Coronavirus Disease 2019 (COVID-19) due to emerging SARS-CoV-2 rose concern about the eventuality of IPA complicating COVID-19 in intensive care unit patients. A variable incidence of such complication has been reported, which can be partly attributed to differences in diagnostic strategy and IPA definitions, and possibly local environmental/epidemiological factors. In this article, we discuss the similarities and differences between influenza-associated pulmonary aspergillosis (IAPA) and COVID-19-associated pulmonary aspergillosis (CAPA). Compared to IAPA, the majority of CAPA cases have been classified as putative rather than proven/probable IPA. Distinct physiopathology of influenza and COVID-19 may explain these discrepancies. Whether CAPA represents a distinct entity is still debatable and many questions remain unanswered, such as its actual incidence, the predisposing role of corticosteroids or immunomodulatory drugs, and the indications for antifungal therapy.

The Single-Component Flavin Reductase/Flavin-Dependent Halogenase AetF is a Versatile Catalyst for Selective Bromination and Iodination of Arenes and Olefins.

Flavin-dependent halogenases (FDHs) natively catalyze selective halogenation of electron rich aromatic and enolate groups. Nearly all FDHs reported to date require a separate flavin reductase to supply them with FADH2 , which complicates biocatalysis applications. In this study, we establish that the single component flavin reductase/flavin dependent halogenase AetF catalyzes halogenation of a diverse set of substrates using a commercially available glucose dehydrogenase to drive its halogenase activity. High site selectivity, activity on relatively unactivated substrates, and high enantioselectivity for atroposelective bromination and bromolactonization was demonstrated. Site-selective iodination and enantioselective cycloiodoetherification was also possible using AetF. The substrate and reaction scope of AetF suggest that it has the potential to greatly improve the utility of biocatalytic halogenation.

Epidemiology of Invasive Pulmonary Aspergillosis Among Intubated Patients With COVID-19: A Prospective Study.

BACKGROUND: We evaluated the incidence of invasive pulmonary aspergillosis among intubated patients with critical COVID-19 and evaluated different case definitions of invasive aspergillosis. METHODS: Prospective, multicenter study in adult patients with microbiologically confirmed COVID-19 receiving mechanical ventilation. All included participants underwent a screening protocol for invasive pulmonary aspergillosis with bronchoalveolar lavage galactomannan and cultures performed on admission at 7 days and in case of clinical deterioration. Cases were classified as coronavirus-associated pulmonary aspergillosis (CAPA) according to previous consensus definitions. The new definition was compared with putative invasive pulmonary aspergillosis (PIPA). RESULTS: 108 patients were enrolled. Probable CAPA was diagnosed in 30 (27.7%) patients after a median of 4 (2-8) days from intensive care unit (ICU) admission. Kaplan-Meier curves showed a significantly higher 30-day mortality rate from ICU admission among patients with either CAPA (44% vs 19%, P = .002) or PIPA (74% vs 26%, P < .001) when compared with patients not fulfilling criteria for aspergillosis. The association between CAPA (OR, 3.53; 95% CI, 1.29-9.67; P = .014) or PIPA (OR, 11.60; 95% CI, 3.24-41.29; P < .001) with 30-day mortality from ICU admission was confirmed, even after adjustment for confounders with a logistic regression model. Among patients with CAPA receiving voriconazole treatment (13 patients; 43%) a trend toward lower mortality (46% vs 59%; P = .30) and reduction in galactomannan index in consecutive samples were observed. CONCLUSIONS: We found a high incidence of CAPA among critically ill COVID-19 patients and its occurrence seems to change the natural course of disease.

Development of a Risk Prediction Model for Carbapenem-resistant Enterobacteriaceae Infection After Liver Transplantation: A Multinational Cohort Study.

BACKGROUND: Patients colonized with carbapenem-resistant Enterobacteriaceae (CRE) are at higher risk of developing CRE infection after liver transplantation (LT), with associated high morbidity and mortality. Prediction model for CRE infection after LT among carriers could be useful to target preventive strategies. METHODS: Multinational multicenter cohort study of consecutive adult patients underwent LT and colonized with CRE before or after LT, from January 2010 to December 2017. Risk factors for CRE infection were analyzed by univariate analysis and by Fine-Gray subdistribution hazard model, with death as competing event. A nomogram to predict 30- and 60-day CRE infection risk was created. RESULTS: A total of 840 LT recipients found to be colonized with CRE before (n = 203) or after (n = 637) LT were enrolled. CRE infection was diagnosed in 250 (29.7%) patients within 19 (interquartile range [IQR], 9-42) days after LT. Pre- and post-LT colonization, multisite post-LT colonization, prolonged mechanical ventilation, acute renal injury, and surgical reintervention were retained in the prediction model. Median 30- and 60-day predicted risk was 15% (IQR, 11-24) and 21% (IQR, 15-33), respectively. Discrimination and prediction accuracy for CRE infection was acceptable on derivation (area under the curve [AUC], 74.6; Brier index, 16.3) and bootstrapped validation dataset (AUC, 73.9; Brier index, 16.6). Decision-curve analysis suggested net benefit of model-directed intervention over default strategies (treat all, treat none) when CRE infection probability exceeded 10%. The risk prediction model is freely available as mobile application at https://idbologna.shinyapps.io/CREPostOLTPredictionModel/. CONCLUSIONS: Our clinical prediction tool could enable better targeting interventions for CRE infection after transplant.

Origin and Control of Chemoselectivity in Cytochrome c Catalyzed Carbene Transfer into Si-H and N-H bonds.

A cytochrome c heme protein was recently engineered to catalyze the formation of carbon-silicon bonds via carbene insertion into Si-H bonds, a reaction that was not previously known to be catalyzed by a protein. High chemoselectivity toward C-Si bond formation over competing C-N bond formation was achieved, although this trait was not screened for during directed evolution. Using computational and experimental tools, we now establish that activity and chemoselectivity are modulated by conformational dynamics of a protein loop that covers the substrate access to the iron-carbene active species. Mutagenesis of residues computationally predicted to control the loop conformation altered the protein's chemoselectivity from preferred silylation to preferred amination of a substrate containing both N-H and Si-H functionalities. We demonstrate that information on protein structure and conformational dynamics, combined with knowledge of mechanism, leads to understanding of how non-natural and selective chemical transformations can be introduced into the biological world.

Managing uncertainty in antifungal dosing: antibiograms, therapeutic drug monitoring and drug-drug interactions.

PURPOSE OF REVIEW: A number of pharmacokinetic and pharmacodynamic factors in critically ill or severely immunosuppressed patients influence the effectiveness of antifungal therapy making dosing less certain. Recent position papers from infectious diseases societies and working groups have proposed methods for dosage individualization of antibiotics in critically ill patients using a combination of population pharmacokinetic models, Monte-Carlo simulation and therapeutic drug monitoring (TDM) to guide dosing. In this review, we examine the current limitations and practical issues of adapting a pharmacometrics-guided dosing approaches to dosing of antifungals in critically ill or severely immunosuppressed populations. RECENT FINDINGS: We review the current status of antifungal susceptibility testing and challenges in incorporating TDM into Bayesian dose prediction models. We also discuss issues facing pharmacometrics dosage adjustment of newer targeted chemotherapies that exhibit severe pharmacokinetic drug-drug interactions with triazole antifungals. SUMMARY: Although knowledge of antifungal pharmacokinetic/pharmacodynamic is maturing, the practical application of these concepts towards point-of-care dosage individualization is still limited. User-friendly pharmacometric models are needed to improve the utility of TDM and management of a growing number of severe pharmacokinetic antifungal drug-drug interactions with targeted chemotherapies.

Breakthrough invasive fungal infection after liver transplantation in patients on targeted antifungal prophylaxis: A prospective multicentre study.

OBJECTIVE: To investigate the rate of and the risk factors for breakthrough-IFI (b-IFI) after orthotopic liver transplantation (OLT) according to the new definition proposed by Mycoses-Study-Group-Education-and-Research-Consortium (MSG-ERC) and the European-Confederation-of-Medical-Mycology (ECMM). METHODS: Multicenter prospective study of adult patients who underwent OLT at three Italian hospitals, from January 2015 to December 2018. Targeted antifungal prophylaxis (TAP) protocol was developed and shared among participating centers. Follow-up was 1-year after OLT. B-IFI was defined as infection occurring during exposure to antifungal prophylaxis. Risk factors for b-IFI were analyzed among patients exposed to prophylaxis by univariable analysis. RESULTS: We enrolled 485 OLT patients. Overall compliance to TAP protocol was 64.3%, 220 patients received antifungal prophylaxis, 172 according to TAP protocol. Twenty-nine patients were diagnosed of IFI within 1 year after OLT. Of them, 11 presented with b-IFI within 17 (IQR 11-33) and 16 (IQR 4-30) days from OLT and from antifungal onset, respectively. Then out of 11 patients with b-IFI were classified as having high risk of IFI and were receiving anti-mould prophylaxis, nine with echinocandins and one with polyenes. Comparison of patients with and without b-IFI showed significant differences for prior Candida colonization, need of renal replacement therapy after OLT, re-operation, and CMV infection (whole blood CMV-DNA >100 000 copies/mL). Although non-significant, a higher rate of b-IFI in patients on echinocandins was observed (8.2% vs 1.8%, P = .06). CONCLUSIONS: We observed 5% of b-IFI among OLT patients exposed to antifungal prophylaxis. The impact of echinocandins on b-IFI risk in this setting should be further explored.

Catalytic iron-carbene intermediate revealed in a cytochrome c carbene transferase.

Recently, heme proteins have been discovered and engineered by directed evolution to catalyze chemical transformations that are biochemically unprecedented. Many of these nonnatural enzyme-catalyzed reactions are assumed to proceed through a catalytic iron porphyrin carbene (IPC) intermediate, although this intermediate has never been observed in a protein. Using crystallographic, spectroscopic, and computational methods, we have captured and studied a catalytic IPC intermediate in the active site of an enzyme derived from thermostable Rhodothermus marinus (Rma) cytochrome c High-resolution crystal structures and computational methods reveal how directed evolution created an active site for carbene transfer in an electron transfer protein and how the laboratory-evolved enzyme achieves perfect carbene transfer stereoselectivity by holding the catalytic IPC in a single orientation. We also discovered that the IPC in Rma cytochrome c has a singlet ground electronic state and that the protein environment uses geometrical constraints and noncovalent interactions to influence different IPC electronic states. This information helps us to understand the impressive reactivity and selectivity of carbene transfer enzymes and offers insights that will guide and inspire future engineering efforts.

Core Recommendations for Antifungal Stewardship: A Statement of the Mycoses Study Group Education and Research Consortium.

In recent years, the global public health community has increasingly recognized the importance of antimicrobial stewardship (AMS) in the fight to improve outcomes, decrease costs, and curb increases in antimicrobial resistance around the world. However, the subject of antifungal stewardship (AFS) has received less attention. While the principles of AMS guidelines likely apply to stewarding of antifungal agents, there are additional considerations unique to AFS and the complex field of fungal infections that require specific recommendations. In this article, we review the literature on AMS best practices and discuss AFS through the lens of the global core elements of AMS. We offer recommendations for best practices in AFS based on a synthesis of this evidence by an interdisciplinary expert panel of members of the Mycoses Study Group Education and Research Consortium. We also discuss research directions in this rapidly evolving field. AFS is an emerging and important component of AMS, yet requires special considerations in certain areas such as expertise, education, interventions to optimize utilization, therapeutic drug monitoring, and data analysis and reporting.

How Long Do We Need to Treat an Invasive Mold Disease in Hematology Patients? Factors Influencing Duration of Therapy and Future Questions.

Treatment duration for invasive mold disease (IMD) in patients with hematological malignancy is not standardized and is a challenging subject in antifungal stewardship. Concerns for IMD relapse during subsequent reinduction or consolidation chemotherapy or graft versus host disease treatment in hematopoietic stem cell transplant recipients often results in prolonged or indefinite antifungal treatment. There are no validated criteria that predict when it is safe to stop antifungals. Decisions are individualized and depend on the offending fungus, site and extent of IMD, comorbidities, hematologic disease prognosis, and future plans for chemotherapy or transplantation. Recent studies suggest that FDG-PET/CT could help discriminate between active and residual fungal lesions to support decisions for safely stopping antifungals. Validation of noninvasive biomarkers for monitoring treatment response, tests for quantifying the "net state of immunosuppression," and genetic polymorphisms associated with poor fungal immunity could lead to a personalized assessment for the continued need for antifungal therapy.

Clinical Pharmacokinetics, Pharmacodynamics, Safety and Efficacy of Liposomal Amphotericin B.

Since its introduction in the 1990s, liposomal amphotericin B (LAmB) continues to be an important agent for the treatment of invasive fungal diseases caused by a wide variety of yeasts and molds. This liposomal formulation was developed to improve the tolerability of intravenous amphotericin B, while optimizing its clinical efficacy. Since then, numerous clinical studies have been conducted, collecting a comprehensive body of evidence on its efficacy, safety, and tolerability in the preclinical and clinical setting. Nevertheless, insights into the pharmacokinetics and pharmacodynamics of LAmB continue to evolve and can be utilized to develop strategies that optimize efficacy while maintaining the compound's safety. In this article, we review the clinical pharmacokinetics, pharmacodynamics, safety, and efficacy of LAmB in a wide variety of patient populations and in different indications, and provide an assessment of areas with a need for further clinical research.

Preclinical Safety, Tolerability, Pharmacokinetics, Pharmacodynamics, and Antifungal Activity of Liposomal Amphotericin B.

The improved safety profile and antifungal efficacy of liposomal amphotericin B (LAmB) compared to conventional amphotericin B deoxycholate (DAmB) is due to several factors including, its chemical composition, rigorous manufacturing standards, and ability to target and transit through the fungal cell wall. Numerous preclinical studies have shown that LAmB administered intravenously distributes to tissues frequently infected by fungi at levels above the minimum inhibitory concentration (MIC) for many fungi. These concentrations can be maintained from one day to a few weeks, depending upon the tissue. Tissue accumulation is dose-dependent with drug clearance occurring most rapidly from the brain and slowest from the liver and spleen. LAmB localizes in lung epithelial lining fluid, within liver and splenic macrophages and in kidney distal tubules. LAmB has been used successfully in therapeutic and prophylactic animal models to treat many different fungal pathogens, significantly increasing survival and reducing tissue fungal burden.

Extended Infusion of ß-Lactams for Bloodstream Infection in Patients With Liver Cirrhosis: An Observational Multicenter Study.

BACKGROUND: We analyzed the impact of continuous/extended infusion (C/EI) vs intermittent infusion of piperacillin-tazobactam (TZP) and carbapenems on 30-day mortality of patients with liver cirrhosis and bloodstream infection (BSI). METHODS: The BICRHOME study was a prospective, multicenter study that enrolled 312 cirrhotic patients with BSI. In this secondary analysis, we selected patients receiving TZP or carbapenems as adequate empirical treatment. The 30-day mortality of patients receiving C/EI or intermittent infusion of TZP or carbapenems was assessed with Kaplan-Meier curves, Cox-regression model, and estimation of the average treatment effect (ATE) using propensity score matching. RESULTS: Overall, 119 patients received TZP or carbapenems as empirical treatment. Patients who received C/EI had a significantly lower mortality rate (16% vs 36%, P = .047). In a Cox-regression model, the administration of C/EI was associated with a significantly lower mortality (hazard ratio [HR], 0.41; 95% confidence interval [CI], 0.11-0.936; P = .04) when adjusted for severity of illness and an ATE of 25.6% reduction in 30-day mortality risk (95% CI, 18.9-32.3; P < .0001) estimated with propensity score matching. A significant reduction in 30-day mortality was also observed in the subgroups of patients with sepsis (HR, 0.21; 95% CI, 0.06-0.74), acute-on-chronic liver failure (HR, 0.29; 95% CI, 0.03-0.99), and a model for end-stage liver disease score ≥25 (HR, 0.26; 95% CI, 0.08-0.92). At competing risk analysis, C/EI of beta-lactams was associated with significantly higher rates of hospital discharge (subdistribution hazard [95% CI], 1.62 [1.06-2.47]). CONCLUSIONS: C/EI of beta-lactams in cirrhotic patients with BSI may improve outcomes and facilitate earlier discharge.

Using State Transition Models to Explore How the Prevalence of Subtherapeutic Posaconazole Exposures Impacts the Clinical Utility of Therapeutic Drug Monitoring for Posaconazole Tablets and Oral Suspension.

Therapeutic drug monitoring (TDM) has been recommended in guidelines for patients receiving posaconazole oral suspension, but its utility in patients receiving posaconazole tablet, which has an improved bioavailability, remains unclear. We used state transition models with first-order Monte Carlo microsimulation to re-examine the posaconazole exposure-response relationships reported in two Phase III clinical trials (prophylaxis with posaconazole oral suspension - Models 1 & 2) and a third multicenter observational TDM study (Model 3). We simulated the impact of TDM-guided interventions to improve initial average posaconazole concentrations (Cavg) to reduce clinical failure (in Models 1 & 2) and breakthrough invasive fungal disease (bIFD) in Model 3. Simulations were then repeated using posaconazole tablet Cavg distributions in place of the oral suspension formulation. In all three models with posaconazole oral suspension, TDM interventions associated with maximal improvement in posaconazole Cavg reduced absolute rates of subtherapeutic exposures (Cavg < 700 ng/mL) by 25-49%. Predicted reductions in absolute clinical failure rates were 11% in Model 1 and 6.5% in Model 2, and a 12.6% reduction in bIFD in Model 3. With the tablet formulation, maximally-effective TDM interventions reduced subtherapeutic exposures by approximately 5% in all three models and absolute clinical failure rates by 3.9% in Model 1, and 1.6% in Model 2; and a 1.6% reduction in bIFD in Model 3. Our modeling suggests that routine TDM during prophylaxis with posaconazole tablets may have limited clinical utility unless populations with higher prevalence (>10%) of subtherapeutic exposures can be identified based on clinical risk factors.