Therapy Of Invasive Fungal Infections Research Articles

Isavuconazole off-label use as an empirical treatment of invasive fungal infections

Given its good tolerance and broad-spectrum, isavuconazole is increasingly used off-label as an empirical therapy of invasive fungal infections. We retrospectively reviewed isavuconazole empirical treatment during a 12-month period in four hospitals. During isavuconazole treatment (n=27), none of the patients had a mycological evidence for fungal infection, but 19% (5/27) developed liver test abnormalities without leading to isavuconazole discontinuation. Isavuconazole could be considered as an off-label empirical therapy only if patients cannot receive caspofungin or liposomal amphotericin B.

A secondary mechanism of action for triazole antifungals in Aspergillus fumigatus mediated by hmg1.

Triazole antifungals function as ergosterol biosynthesis inhibitors and are frontline therapy for invasive fungal infections, such as invasive aspergillosis. The primary mechanism of action of triazoles is through the specific inhibition of a cytochrome P450 14-α-sterol demethylase enzyme, Cyp51A/B, resulting in depletion of cellular ergosterol. Here, we uncover a clinically relevant secondary mechanism of action for triazoles within the ergosterol biosynthesis pathway. We provide evidence that triazole-mediated inhibition of Cyp51A/B activity generates sterol intermediate perturbations that are likely decoded by the sterol sensing functions of HMG-CoA reductase and Insulin-Induced Gene orthologs as increased pathway activity. This, in turn, results in negative feedback regulation of HMG-CoA reductase, the rate-limiting step of sterol biosynthesis. We also provide evidence that HMG-CoA reductase sterol sensing domain mutations previously identified as generating resistance in clinical isolates of Aspergillus fumigatus partially disrupt this triazole-induced feedback. Therefore, our data point to a secondary mechanism of action for the triazoles: induction of HMG-CoA reductase negative feedback for downregulation of ergosterol biosynthesis pathway activity. Abrogation of this feedback through acquired mutations in the HMG-CoA reductase sterol sensing domain diminishes triazole antifungal activity against fungal pathogens and underpins HMG-CoA reductase-mediated resistance.

A Practical Guide to Antifungal Susceptibility Testing.

We review antifungal susceptibility testing and the development of clinical breakpoints, and detail an approach to using antifungal susceptibility results when breakpoints have not been defined. This information may prove helpful when selecting therapy for invasive fungal infections in children.

Comparing the Real-World Use of Isavuconazole to Other Anti-Fungal Therapy for Invasive Fungal Infections in Patients with and without Underlying Disparities: A Multi-Center Retrospective Study

Invasive fungal infections (IFIs) are a major cause of morbidity and mortality among immunocompromised patients with underlying malignancies and prior transplants. FDA approved Isavuconazole as a primary therapy for Invasive Aspergillosis (IA) and Mucormycosis. This study aims to compare the real-world clinical outcomes and safety of isavuconazole to voriconazole and an amphotericin B-based regimen in patients with underlying malignancies and a transplant. In addition, the response to anti-fungal therapy and the outcome were compared among patients with a disparity (elderly, obese patients, patients with renal insufficiency and diabetes mellitus) versus those with no disparity. We performed a multicenter retrospective study, including patients with cancer diagnosed with an invasive fungal infection, and treated primarily with isavuconazole, voriconazole or amphotericin B. Clinical, radiologic findings, response to therapy and therapy related adverse events were evaluated during 12 weeks of follow-up. We included 112 patients aged 14 to 77 years, and most of the IFIs were classified into definite (29) or probable (51). Most cases were invasive aspergillosis (79%), followed by fusariosis (8%). Amphotericin B were used more frequently as primary therapy (38%) than isavuconazole (30%) or voriconazole (31%). Twenty one percent of the patients presented adverse events related to primary therapy, with patients receiving isavuconazole presenting less adverse events when compared to voriconazole and amphotericin (p < 0.001; p = 0.019). Favorable response to primary therapy during 12 weeks of follow-up were similar when comparing amphotericin B, isavuconazole or voriconazole use. By univariate analysis, the overall cause of mortality at 12 weeks was higher in patients receiving amphotericin B as primary therapy. However, by multivariate analysis, Fusarium infection, invasive pulmonary infection or sinus infection were the only independent risk factors associated with mortality. In the treatment of IFI for patients with underlying malignancy or a transplant, Isavuconazole was associated with the best safety profile compared to voriconazole or amphotericin B-based regimen. Regardless of the type of anti-fungal therapy used, invasive Fusarium infections and invasive pulmonary or sinus infections were the only risk factors associated with poor outcomes. Disparity criteria did not affect the response to anti-fungal therapy and overall outcome, including mortality.

Indications that the Antimycotic Drug Amphotericin B Enhances the Impact of Platelets on Aspergillus.

ABSTRACTPlatelets are currently thought to harbor antimicrobial functions and might therefore play a crucial role in infections, e.g., those caused by Aspergillus or mucormycetes. The incidence of invasive fungal infections is increasing, particularly during the coronavirus disease 2019 (COVID-19) pandemic, and such infections continue to be life-threatening in immunocompromised patients. For this reason, the interaction of antimycotics with platelets is a key issue to evaluate modern therapeutic regimens. Amphotericin B (AmB) is widely used for the therapy of invasive fungal infections either as deoxycholate (AmB-D) or as a liposomal formulation (L-AmB). We showed that AmB strongly activates platelets within a few minutes. AmB concentrations commonly measured in the blood of patients were sufficient to stimulate platelets, indicating that this effect is highly relevant in vivo. The stimulating effect was corroborated by a broad spectrum of platelet activation parameters, including degranulation, aggregation, budding of microparticles, morphological changes, and enhanced adherence to fungal hyphae. Comparison between the deoxycholate and the liposomal formulation excluded the possibility that the liposomal part of L-Amb is responsible for these effects, as no difference was visible. The induction of platelet activation and alteration by L-AmB resulted in the activation of other parts of innate immunity, such as stimulation of the complement cascade and interaction with granulocytes. These mechanisms might substantially fuel the antifungal immune reaction in invasive mycoses. On the other hand, thrombosis and excessive inflammatory processes might occur via these mechanisms. Furthermore, the viability of L-AmB-activated platelets was consequently decreased, a process that might contribute to thrombocytopenia in patients.

Antifungal combination therapy for invasive fungal infections in a paediatric oncology and haematology department: A retrospective analysis of practice.

Invasive fungal infections (IFI) are an important cause of morbidity and mortality in children with leukaemia. International guidelines recommend a monotherapy for most IFI. The use of antifungal combination therapy (ACT) has been reported, but clinical data supporting these combinations are scarce, particularly in paediatrics. To describe, among patients treated in our department, the situations in which an ACT was used. Between January 2017 and December 2020, 239 patients (406 hospital stays) benefited from systemic antifungals. Among them, ACT was prescribed for 14 (5.9%) patients (13 leukaemia, 1 aplastic anaemia) corresponding to 16 (3.9%) hospital stays. IFI cases treated with ACT were mainly proven (n=9) or probable (n=4). Seven cases required admission to the intensive care unit. The most commonly used antifungal agents were liposomal amphotericin B (n=13), caspofungin (n=12) and voriconazole (n=9). In 13 cases, monotherapy was prescribed as first-line therapy and changed to an ACT for an uncontrolled infection. But in 3 cases, the ACT was started immediately. The response at 12 weeks after diagnosis of proven/probable IFI was successful in 12 cases (92.3%). The only IFI-related death was attributed to disseminated mucormycosis. ACT were generally well tolerated. In 4 cases, adverse events led to the discontinuation of the offending antifungal agent. This retrospective analysis of practices shows that the use of ACT in our paediatric haemato-oncology department is rare, and concerns the most severe cases and/or those not responding to the first line treatment. In most cases, ACT was efficient and well tolerated.

Real-World Use of Isavuconazole as Primary Therapy for Invasive Fungal Infections in High-Risk Patients with Hematologic Malignancy or Stem Cell Transplant.

(1) Introduction: Invasive fungal infections (IFIs) are a major cause of morbidity and mortality among immunocompromised patients with hematologic malignancies (HM) and stem cell transplants (SCT). Isavuconazole was approved by FDA as a primary therapy for Invasive Aspergillosis (IA) and Mucormycosis. The aim of this study is to look at the real-world use of Isavuconazole in patients with HM and evaluate their clinical outcomes and safety. (2) Methods: We conducted a retrospective study of HM patients at MD Anderson Cancer Center who had definite, probable or possible mold infections between 1 April 2016 and 31 January 2020 and were treated with Isavuconazole for a period of at least 7 days. Clinical and radiological findings were assessed at baseline and at 6 and 12 weeks of follow up. (3) Results: We included 200 HM patients with IFIs that were classified as definite (11), probable (63) and possible (126). Aspergillus spp was the most commonly isolated pathogen. The majority of patients (59%) received prophylaxis with anti-mold therapy and Isavuconazole was used as a primary therapy in 43% of patients, and as salvage therapy in 58%. The switch to Isavuconazole was driven by the failure of the primary therapy in 66% of the cases and by adverse effects in 29%. Isavuconazole was used as monotherapy in 30% of the cases and in combination in 70%. Adverse events possibly related to Isavuconazole were reported in eight patients (4%) leading to drug discontinuation. Moreover, a favorable response with Isavuconazole was observed in 40% at 6 weeks and in 60% at 12 weeks. There was no significant difference between isavuconazole monotherapy and combination therapy (p = 0.16 at 6 weeks and p = 0.06 at 12 weeks). Finally, there was no significant difference in outcome when Isavuconazole was used after failure of other anti-mold prophylaxis or treatment versus when used de novo as an anti-mold therapy (p = 0.68 at 6 weeks and p = 0.25 at 12 weeks). (4) Conclusions: Whether used as first-line therapy or after the failure of other azole and non-azole prophylaxis or therapies, isavuconazole seems to have a promising clinical response and a good safety profile as an antifungal therapy in high-risk cancer patients with hematologic malignancies. Moreover, combination therapy did not improve the outcome compared to Isavuconazole therapy.

Efficacy and Safety of Combination Antifungal Therapy in Empirical, Proactive and Target Therapy of Invasive Fungal Infections in Intensive Care Units

Efficacy and Safety of Combination Antifungal Therapy in Empirical, Proactive and Target Therapy of Invasive Fungal Infections in Intensive Care Units

Development of a Method of Measuring β-D-Glucan and Its Use in Preemptive Therapy for Invasive Fungal Infections

Invasive fungal infections (IFIs) are serious infections that develop in conjunction with neutropenia after chemotherapy for acute leukemia or with hematopoietic stem cell transplantation. Conventionally, empirical antifungal therapy was recommended to treat IFIs for patient safety despite a lack of evidence of fungal infections. However, many studies have indicated that antifungals were not necessary for over half of patients, and several detriments of empirical therapy were noted, e.g., antifungals caused adverse reactions, an increase in drug-resistant fungi was a possibility, and medical costs soared. β-D-glucan (BDG) is a component of clinically important fungi such as Aspergillus and Candida. The G-test was developed in Japan as a way to measure BDG in serum using a coagulation factor from the blood of the horseshoe crab. Pre-emptive antifungal therapy based upon serodiagnosis with a BDG or galactomannan assay and CT imaging has been introduced. With pre-emptive antifungal therapy, the prognosis is equivalent to that with empirical therapy, and the dose of the antifungal has been successfully reduced. Measurement of BDG has been adopted widely as a method of diagnosing IFIs and is listed in the key guidelines for fungal infections and febrile neutropenia.

1182. The Real-World Use of Isavuconazole as Primary or salvage Therapy of Invasive Fungal infections in High-Risk Patients with Hematologic Malignancy or Stem Cell Transplant

BackgroundInvasive fungal infections (IFIs) are a major cause of morbidity and mortality among immunocompromised patients with hematologic malignancies (HM) and stem cell transplants (SCT). Isavuconazole was approved by FDA as a primary therapy for Invasive Aspergillosis (IA) and Mucormycosis. The aim of this study is to look at the real-world use of Isavuconazole in patients with HM and evaluate their clinical outcomes and safety.MethodsWe conducted a retrospective study of 200 HM patients at MD Anderson Cancer Center who had definite, probable or possible mold infections between April 2016 and January 2020 and were treated with Isavuconazole for a period of at least 7 days. Clinical and radiological findings were assessed at baseline and at 6 and 12 weeks of follow up.ResultsHM patients with IFIs were classified as definite (11), probable (66) and possible (123). IA was the most commonly isolated pathogen followed by mucor and candida. The majority of patients (65%) received prophylaxis with anti-mold therapy, 73% consisted of azoles and 22% of echinocandins. Isavuconazole was used as a primary therapy in 57.5% of patients, and as salvage therapy in 42.5%. The switch to Isavuconazole was driven by failure of the primary therapy in 50% of the cases and by adverse effects in 28%. These included elevated liver function tests (LFTs), subtherapeutic voriconazole levels and prolonged QT. Isavuconazole was used as monotherapy in 30% of the cases and combination in 70% mostly with a polyene (54%) and/or an echinocandin (27%). A favorable response with Isavuconazole was observed in 57% at 6 weeks of therapy. Adverse events possibly related to Isavuconazole were reported in 6 patients (3%) leading to drug discontinuation. These included 5 elevated transaminases and 1 nausea. All-cause mortality was reported in 46% of patients and IFI-attributable mortality in 25%.ConclusionSelecting Isavuconazole therapy was mainly driven by failure of other antifungal agents or adverse events to other antifungals such as increased LFTs, subtherapeutic voriconazole levels or prolonged QT. Isavuconazole seems to have a promising clinical response and a good safety profile as an antifungal therapy in high risk cancer patients with HM.Disclosures Issam I. Raad, MD, Citius (Other Financial or Material Support, Ownership interest)Cook Medical (Grant/Research Support)Inventive Protocol (Other Financial or Material Support, Ownership interest)Novel Anti-Infective Technologies (Shareholder, Other Financial or Material Support, Ownership interest)

Combination Therapy for Invasive Fungal Infections

The purpose of this review is to summarize and evaluate relevant literature on combination antifungal therapy for invasive fungal infections (IFIs). Cryptococcal meningitis has the largest body and highest quality in support of combination therapy with amphotericin B and flucytosine. More recent data in treatment of invasive aspergillosis suggest combination therapy with voriconazole and echinocandins may be effective in select patients. Quality studies are needed to define combination therapy in rare mold infections. Multiple strategies have been employed to optimize treatment of the growing incidence of IFIs. With exceptions as noted above, justification for the use of combination antifungal therapy is most often based on uncontrolled and/or underpowered studies, in vitro data, and case reports.

Synthesis of novel papulacandin D analogs and evaluation of their antifungal potential

Systemic fungal infections are a growing problem in contemporary medicine and few drugs are licensed for therapy of invasive fungal infections. Differences between fungi and humans, like the presence of a cell wall in fungal cells, can be explored for designing new drugs. (1,3)-β-D-glucan synthase, an enzyme that catalyzes the synthesis of (1,3)-β-D-glucan, a structural and essential component of the fungal cell wall, is absent in mammals and this makes it an excellent target for the development of new antifungal agents. Papulacandins are a family of natural antifungal agents targeting (1,3)-β-D-glucan synthase. In this study we describe the synthesis and biological evaluation of two new Papulacandin analogs as potential (1,3)-β-D-glucan synthase inhibitors.

Risk Factors Associated With Invasive Fungal Infections in Kidney Transplant Patients

BackgroundKidney transplant recipients are at increased risk for developing invasive fungal infections (IFI). We queried the United States Renal Data System (USRDS) for risk factors for IFI in these patients. MethodsPatients who underwent a kidney transplant between 2005 and 2008 were queried for an IFI diagnosis using ICD-9 codes. An IFI was defined as at least one documented diagnosis from one of the following: (1) Candida (candidemia); (2) Histoplasmosis; (3) Aspergillosis; (4) Cryptococcosis; (5) “Other” mycoses. Potential risk factors included demographics, certain comorbidities and immunosuppressive medications. To examine the relative risk (RR), simple bivariate models were used, followed by a comprehensive full model to estimate the adjusted RR (aRR). ResultsOf 57,188 kidney transplant patients, 1,218 had 1,343 IFI diagnoses, with a median time to infection of 495 days. “Other” mycoses accounted for the most IFI diagnoses (37%), followed by aspergillosis (22%). The risk for any IFI was increased with age ≥65 years. Diabetes (aRR = 1.71), bacterial pneumonia (aRR = 1.62) and UTI (aRR = 1.34) were the top 3 clinical risk factors for infection. Each of the IFI groups was also associated with individual risk factors. Therapy with mycophenolate mofetil was associated with a decreased risk of candidemia. ConclusionsRisk factors for IFI in renal transplant patients include demographic, medication-associated and clinical data, as well as organism-specific factors. These results offer an extensive clinical profile of risk for IFI, and may thus help inform the diagnosis and presumptive therapy of invasive fungal infections in renal transplant recipients.

Biosynthesis of pneumocandin lipopeptides and perspectives for its production and related echinocandins

Fungal diseases are a global public health problem. Invasive fungal infections pose a serious threat to patients with compromised immune systems, such as those undergoing organ or bone marrow transplants, cancer, or HIV/AIDS. Pneumocandins are antifungal lipohexapeptides of the echinocandin family that noncompetitively inhibit of 1,3-β-glucan synthase of fungal cell wall and provide the precursor for the semisynthesis of caspofungin, which is widely used as first-line therapy for invasive fungal infections. Recently, the biosynthetic steps leading to formation of pneumocandin B0 and echinocandin B have been elucidated, and thus, provide a framework and attractive model for further design new antifungal therapeutics around natural variations in echinocandin structural diversities via genetic and chemical tools. In this article, we analyze the biosynthetic pathway of pneumocandins and other echinocandins, provide an update on the array of pneumocandin analogues generated by genetic manipulation, and summarize advances in the enhancement of pneumocandin B0 production by random mutagenesis and fermentation optimization. We also give offer advice on the development of improved pneumocandin drug candidates and more efficient production of pneumocandin B0.

A Class 1 Histone Deacetylase with Potential as an Antifungal Target.

ABSTRACTHistone deacetylases (HDACs) remove acetyl moieties from lysine residues at histone tails and nuclear regulatory proteins and thus significantly impact chromatin remodeling and transcriptional regulation in eukaryotes. In recent years, HDACs of filamentous fungi were found to be decisive regulators of genes involved in pathogenicity and the production of important fungal metabolites such as antibiotics and toxins. Here we present proof that one of these enzymes, the class 1 type HDAC RpdA, is of vital importance for the opportunistic human pathogen Aspergillus fumigatus. Recombinant expression of inactivated RpdA shows that loss of catalytic activity is responsible for the lethal phenotype of Aspergillus RpdA null mutants. Furthermore, we demonstrate that a fungus-specific C-terminal region of only a few acidic amino acids is required for both the nuclear localization and catalytic activity of the enzyme in the model organism Aspergillus nidulans. Since strains with single or multiple deletions of other classical HDACs revealed no or only moderate growth deficiencies, it is highly probable that the significant delay of germination and the growth defects observed in strains growing under the HDAC inhibitor trichostatin A are caused primarily by inhibition of catalytic RpdA activity. Indeed, even at low nanomolar concentrations of the inhibitor, the catalytic activity of purified RpdA is considerably diminished. Considering these results, RpdA with its fungus-specific motif represents a promising target for novel HDAC inhibitors that, in addition to their increasing impact as anticancer drugs, might gain in importance as antifungals against life-threatening invasive infections, apart from or in combination with classical antifungal therapy regimes.

Terapia inwazyjnych grzybic układowych w świetle międzynarodowych rekomendacji

Terapia inwazyjnych grzybic układowych w świetle międzynarodowych rekomendacji

An Automated High-Throughput Cell-Based Multiplexed Flow Cytometry Assay to Identify Novel Compounds to Target Candida albicans Virulence-Related Proteins

Although three major classes of systemic antifungal agents are clinically available, each is characterized by important limitations. Thus, there has been considerable ongoing effort to develop novel and repurposed agents for the therapy of invasive fungal infections. In an effort to address these needs, we developed a novel high-throughput, multiplexed screening method that utilizes small molecules to probe candidate drug targets in the opportunistic fungal pathogen Candida albicans. This method is amenable to high-throughput automated screening and is based upon detection of changes in GFP levels of individually tagged target proteins. We first selected four GFP-tagged membrane-bound proteins associated with virulence or antifungal drug resistance in C. albicans. We demonstrated proof-of-principle that modulation of fluorescence intensity can be used to assay the expression of specific GFP-tagged target proteins to inhibitors (and inducers), and this change is measurable within the HyperCyt automated flow cytometry sampling system. Next, we generated a multiplex of differentially color-coded C. albicans strains bearing C-terminal GFP-tags of each gene encoding candidate drug targets incubated in the presence of small molecules from the Prestwick Chemical Library in 384-well microtiter plate format. Following incubation, cells were sampled through the HyperCyt system and modulation of protein levels, as indicated by changes in GFP-levels of each strain, was used to identify compounds of interest. The hit rate for both inducers and inhibitors identified in the primary screen did not exceed 1% of the total number of compounds in the small-molecule library that was probed, as would be expected from a robust target-specific, high-throughput screening campaign. Secondary assays for virulence characteristics based on null mutant strains were then used to further validate specificity. In all, this study presents a method for the identification and verification of new antifungal drugs targeted to fungal virulence proteins using C. albicans as a model fungal pathogen.

Early empiric therapy for invasive fungal infection in the ICU

The risk of infection increases with the length of stay in the intensive care unit (ICU). Invasive fungal infections (IFI) are now responsible for a sizeable proportion of ICU infections. Candida spp. are a particular problem in the ICU, where they are not only among the most common pathogens responsible for blood stream infections (BSI), but also associated with an unexpectedly high rate of mortality. Central venous catheters, total parenteral nutrition, and increasingly, surgery, are common sources of Candida BSI. While C. albicans remains the most common species implicated in candidemia, C. glabrata, C. parapsilosis, C. tropicalis, C. krusei, and other non-albicans species are often responsible for infection, especially among older patients (e.g., > 60 years). Risk scores and prediction rules for Candida BSI are helpful, but not straightforward to apply. There is also uncertainty around the appropriate length of therapy for deep-seated Candida infections (e. g., intra-abdominal infections). Despite predictive, diagnostic, and treatment uncertainties, correct assessment of patient risk factors for nosocomial Candida infection is crucial to avoiding the poor outcomes associated with delayed or inappropriate initial therapy. The reality is that many ICU patients with Candida IFI are treated late or with fluconazole despite guidelines that an echinocandin be used as initial therapy for critically ill patients. Furthermore, not all echinocandins are equally effective, particularly when it comes to non-albicans Candida infections. The problem of antifungal agents not being interchangeable extends to treatment of invasive aspergillosis, where selecting an agent such as voriconazole gives rise to concerns about drug interactions and the need for therapeutic drug monitoring. Given the increasing problem of candidemia in the ICU and the shift to non-albicans species, especially in older patients, early empiric therapy with an echinocandin is essential, as is consideration of surgical co-intervention when urgent measures are needed. Early empiric therapy with the appropriate echinocandin and source control are the cornerstones of effective treatment for Candida BSI.

Combination antifungal therapy for invasive fungal infections in children and adults

Although therapeutic first-line approaches have been established in severely immunosuppressed patients with a high risk of invasive fungal infections, treatment modalities for cases with unsatisfactory outcome have not been well defined, especially for the pediatric age gap. Therapy with coadministration of two or three antifungals has been applied by clinicians in difficult-to-treat infections, which still have no support from randomized, controlled clinical trials. The most prevailing reason for a combination regimen is to broaden the antimycotic spectrum, which may even result in antagonistic interaction. The experience and recommendations of combinational antifungal therapy for cryptococcal infections, systemic candidiasis, invasive aspergillosis and other rare mold infections have been presented in this review, giving some information on mechanism of action and principles in combined use of mycotic anti-infectives. Most experience of combination therapy approaches are in adult patients; but in fact, there is no conclusive data documenting definite benefits of this approach, either in adults or children.

Posaconazole Prophylaxis in Patients Undergoing Chemotherapy for Acute Myeloid Leukemia: A Single Center Experience of Therapeutic Drug Monitoring.

AbstractAbstract 2595▪▪This icon denotes a clinically relevant abstract Background:Posaconazole is indicated for prophylaxis and salvage therapy of invasive fungal infections. Based on pharmacokinetic-pharmacodynamic data, a minimum serum concentration higher than 0.5 mg/L and 1.0 mg/L has been proposed for prophylaxis and therapy, respectively. While therapeutic drug monitoring (TDM) of plasma concentrations is widely accepted for triazole antifungal agents such as voriconazole, the utility of TDM for posaconazole is controversial due to debate over the relationship between posaconazole exposure in plasma and clinical response to therapy. In fact only few reports correlate posaconazole plasma concentrations (PPCs) with breakthrough infection. Methods:In this retrospective single center study we evaluated the correlation of PPCs with breakthrough invasive mould infections (IMIs) in 50 patients with acute myeloid leukaemia (AML) who underwent chemoterapy (induction or salvage therapy) between July 2009 and March 2012. To measure the posaconazole concentration in human plasma, we developed and validated a rapid and simple high-performance liquid chromatography method. The method involved a solid-phase extraction of posaconazole using Oasis HLB cartridges, a reversed-phase liquid chromatography on an XTerra RP18 column with a mobile phase consisting of acetonitrile/ammonium acetate and ultraviolet detection.Patient characteristics and microbiological data such galactomannan detection and TDM were collected retrospectively.A total of 454 PPCs were measured before and 4 hours after administration in 50 patients with AML receiving posaconazole prophylaxis at dose of 200 mg 3 times/day. When plasma levels were below 0.5 mg/L, the dose was increased to 200 mg 4 times/day. Results:Average levels below the target of 0.5 μg/mL were detected in 38 (76%) out of 50 cases; 5 out of 38 cases showed plasma concentrations <0.20 μg/mL. Six patients (12%) receiving PCZ prophylaxis met the criteria of breakthrough infection (5 possible and 1 probable). Noteworthy, none of these patients achieved a complete remission after chemotherapy. Prior to development of IMIs, PPCs were below the target in 4 out of 6 (66%) cases experiencing breakthrough infection (between 0.2 and 0.5 μg/mL). Interestingly, only one patient had galactomannan positivity in the bronchoalveolar lavage fluid whereas none of the cases had serum galactomannan. Furthermore, out of 13 patients with resistant disease who did not develop IMIs, 8 (62%) presented PCPs < 0.5 μg/mL. Conclusions:Our data demonstrate that low PPCs are common in patients receiving posaconazole prophylaxis during chemotherapy for AML. However, in spite of low PPCs, the rate of IMIs was low. This is possibly due to the good lung bioavailability of the drug, despite the presence of low drug serum levels. In addition, our data seems to confirm that refractory disease is a strong risk factor for the development of IMIs. Even in this high risk group, low PPCs did not correlate with high IMIs' incidence. A prospective evaluation of TDM of posaconazole is needed. Disclosures:No relevant conflicts of interest to declare.