Isavuconazole: A New Broad-Spectrum Triazole Antifungal Agent

Gastric Mucormycosis in a Liver and Kidney Transplant Recipient: Case Report and Concise Review of Literature

Mucormycosis is an uncommonly encountered fungal infection in solid organ transplantation. The infection is severe and often results in a fatal outcome. The most common presentations are rhino-sino-orbital and pulmonary disease. We describe a rare case of gastric mucormycosis in a patient with a combined liver-kidney transplant affected by glycogen storage disease type Ia. A 42-year-old female patient presented with gastric pain and melena 26 days after transplantation. Evaluation with upper endoscopy showed two bleeding gastric ulcers. Histological examination of gastric specimens revealed fungal hyphae with evidence of Mucormycetes at subsequent molecular analysis. Immunosuppressive therapy was reduced and antifungal therapy consisting of liposomal amphotericin B and posaconazole was promptly introduced. Gastrointestinal side effects of posaconazole and acute T-cell rejection of renal graft complicated management of the case. A prolonged course of daily injections of amphotericin B together with a slight increase of immunosuppression favored successful treatment of mucormycosis as well as of graft rejection. At 2-year follow-up, the woman was found to have maintained normal renal and liver function. We conclude that judicious personalization of antimicrobial and antirejection therapy should be considered to resolve every life-threatening case of mucormycosis in solid organ transplantation.

Hyperbaric Oxygen Reduces Aspergillus fumigatus Proliferation In Vitro and Influences In Vivo Disease Outcomes

Recent estimates suggest that more than 3 million people have chronic or invasive fungal infections, causing more than 600,000 deaths every year. Aspergillus fumigatus causes invasive pulmonary aspergillosis (IPA) in patients with compromised immune systems and is a primary contributor to increases in human fungal infections. Thus, the development of new clinical modalities as stand-alone or adjunctive therapy for improving IPA patient outcomes is critically needed. Here we tested the in vitro and in vivo impacts of hyperbaric oxygen (HBO) (100% oxygen, >1 atmosphere absolute [ATA]) on A. fumigatus proliferation and murine IPA outcomes. Our findings indicate that HBO reduces established fungal biofilm proliferation in vitro by over 50%. The effect of HBO under the treatment conditions was transient and fungistatic, with A. fumigatus metabolic activity rebounding within 6 h of HBO treatment being removed. In vivo, daily HBO provides a dose-dependent but modest improvement in murine IPA disease outcomes as measured by survival analysis. Intriguingly, no synergy was observed between subtherapeutic voriconazole or amphotericin B and HBO in vitro or in vivo with daily HBO dosing, though the loss of fungal superoxide dismutase genes enhanced HBO antifungal activity. Further studies are needed to optimize the HBO treatment regimen and better understand the effects of HBO on both the host and the pathogen during a pulmonary invasive fungal infection.

Antifungal Resistance in Dermatology

Cutaneous fungal infections affect more than one-fourth of world's population. The pathogenesis and severity of fungal infection depend on various immunological and nonimmunological factors. The rampant use of antifungal therapy in immunocompromised individuals marked the onset of antifungal drug resistance. Fungal resistance can be microbiological or clinical. Microbiological resistance depends on various fungal factors which have established due to genetic alteration in the fungi. Clinical resistance is due to host- or drug-related factors. All these factors may cause fungal resistance individually or in tandem. In addition to standardized susceptibility testing and appropriate drug dosing, one of the ways to avoid resistance is the use of combinational antifungal therapy. Combination therapy also offers advantages in increased synergistic action with enhanced spectrum activity. Newer insights into mechanisms of drug resistance will help in the development of appropriate antifungal therapy.

In Vitro Combination of Isavuconazole with Echinocandins against Azole-Susceptible and -Resistant Aspergillus spp

In vitro combinations of isavuconazole with echinocandins were evaluated against 30 Aspergillus strains with a two-dimensional checkerboard microdilution method and an agar-based diffusion method. With the checkerboard method, the three combinations showed indifferent interactions for all strains. With the agar-based method, indifferent interactions were found for all strains for isavuconazole-micafungin and isavuconazole-anidulafungin. For the isavuconazole-caspofungin combination, indifference was found in 24/30 strains, synergism in 4/30 strains, and antagonism in 2/30 strains.

Challenges and Solution of Invasive Aspergillosis in Non-neutropenic Patients: A Review

Invasive aspergillosis (IA) is a serious opportunistic infection, which has increasingly been recognized as an emerging disease of non-neutropenic patients. In this group of patients, the diagnosis of IA can be challenging owing to the lack of specificity of symptoms, the difficulty in discriminating colonization from infection, and the lower sensitivity of microbiological and radiological tests compared with immunocompromised patients. The aim of this article is to present to clinicians a critical review on the management of IA in non-neutropenic patients.

Antifungal Drugs in Newborns and Children

Invasive fungal infections are a significant cause of morbidity and mortality in infants and children. Early diagnosis is critical, and treatment with the appropriate drug and dose should be initiated promptly. Although an increasing number of studies have examined dosing of antifungals in this population, pediatric safety and efficacy data are lacking.

Tissue Distribution and Elimination of Isavuconazole following Single and Repeat Oral-Dose Administration of Isavuconazonium Sulfate to Rats

Quantitative whole-body autoradiography was used to assess the distribution and tissue penetration of isavuconazole in rats following single and repeated oral-dose administration of radiolabeled isavuconazonium sulfate, the prodrug of isavuconazole. Following a single-dose administration of radiolabeled isavuconazonium sulfate (labeled on the active moiety), radioactivity was detectable within 1 h postdose in 56 of 65 tissue/fluid specimens. The highest maximum concentrations (C_max) were observed in bile and liver (66.6 and 24.7 μg eq/g, respectively). The lowest C_max values were in bone and eye lens (0.070 and 0.077 μg eq/g, respectively). By 144 h postdose, radioactivity was undetectable in all tissues/fluids except liver (undetectable at 336 h) and adrenal gland tissues (undetectable at 672 h). Following daily administration for up to 21 days, 1-h-postdose C_max values were the highest on or before day 14 in all except seven tissues/fluids, of which only rectum mucosa and small intestine mucosa had C_max values >25% higher than all other 1-h-postdose values. For 24-h-postdose C_max values, only large intestine, large intestine mucosa, and urine had the highest C_max values at day 21. The penetration of single oral doses of unlabeled isavuconazole (25 mg/kg of body weight isavuconazonium sulfate) and voriconazole (50 mg/kg) into rat brain (assessed using liquid chromatography-tandem mass spectrometry) was also compared. Brain concentration/plasma concentration ratios reached approximately 1.8:1 and 2:1, respectively. These data suggest that isavuconazole penetrates most tissues rapidly, reaches a steady state in most or all tissues/fluids within 14 days, does not accumulate in tissues/fluids over time, and achieves potentially efficacious concentrations in the brain.

Destination of aminoglycoside antibiotics in the 'post-antibiotic era'

Aminoglycoside antibiotics (AGAs) were developed at the dawn of the antibiotics era and have significantly aided in the treatment of infectious diseases. Aminoglycosides have become one of the four major types of antibiotics in use today and, fortunately, still have an important role in the clinical treatment of severe bacterial infections. In this review, the current usage, modes of action and side effects of AGAs, along with the most common bacterial resistance mechanisms, are outlined. Finally, the recent development situation and possibility of new AGAs in the 'post-antibiotic era' are considered.The Journal of Antibiotics advance online publication, 25 October 2017; doi:10.1038/ja.2017.117.

Azole-Resistant Aspergillosis: Epidemiology, Molecular Mechanisms, and Treatment

Aspergillus fumigatus remains the most common species in all pulmonary syndromes, followed by Aspergillus flavus which is a common cause of allergic rhinosinusitis, postoperative aspergillosis and fungal keratitis. The manifestations of Aspergillus infections include invasive aspergillosis, chronic pulmonary aspergillosis and bronchitis. Allergic manifestations of inhaled Aspergillus include allergic bronchopulmonary aspergillosis and severe asthma with fungal sensitization. Triazoles are the mainstay of therapy against Aspergillus infections for treatment and prophylaxis. Lately, increased azole resistance in A. fumigatus has become a significant challenge in effective management of aspergillosis. Earlier studies have brought to light the contribution of non-cyp51 mutations along with alterations in cyp51A gene resulting in azole-resistant phenotypes of A. fumigatus. This review highlights the magnitude of azole-resistant aspergillosis and resistance mechanisms implicated in the development of azole-resistant A. fumigatus and address the therapeutic options available.

Green ultrasound-assisted three-component click synthesis of novel 1H-1,2,3-triazole carrying benzothiazoles and fluorinated-1,2,4-triazole conjugates and their antimicrobial evaluation

The present study describes an efficient and ecofriendly, ultrasound, one-pot click cycloaddition approach for the construction of a novel series of 1,4-disubstituted-1,2,3-triazoles tethered with fluorinated 1,2,4-triazole-benzothiazole molecular conjugates. It involved three-component condensation of the appropriate bromoacetamide benzothiazole, sodium azide and 4-alkyl/aryl-5-(2-fluorophenyl)-3-(prop-2-ynylthio)-1,2,4-triazoles 4a-e through a Cu(I)-catalyzed 1,3-dipolar cycloaddition reaction. This approach involves in situ generation of azidoacetamide benzothiazole, followed by condensation with terminal alkynes in the presence of CuSO4/Na-ascorbate in aqueous DMSO under both conventional and ultrasound conditions. Some of the designed 1,2,3-triazole conjugates 6a-o were recognized for their antimicrobial activity against some bacterial and fungal pathogenic strains.

Combination Therapy with Isavuconazole and Micafungin for Treatment of Experimental Invasive Pulmonary Aspergillosis

Invasive pulmonary aspergillosis (IPA) is an important cause of morbidity and mortality in immunocompromised patients. We hypothesized that simultaneous inhibition of biosynthesis of ergosterol in the fungal cell membrane and (1→3)-β-d-glucan in the cell wall, respectively, by the antifungal triazole isavuconazole (ISA) and the echinocandin micafungin (MFG) may result in improved outcomes in experimental IPA in persistently neutropenic rabbits. Treatments included ISA at 20 mg/kg of body weight/day (ISA20), 40 mg/kg/day (ISA40), and 60 mg/kg/day (ISA60); MFG at 2 mg/kg/day (MFG2); combinations of ISA20 and MFG2, ISA40 and MFG2, and ISA60 and MFG2; and no treatment (untreated controls [UC]). The galactomannan index (GMI) and (1→3)-β-d-glucan levels in serum were measured. The residual fungal burden (number of CFU per gram) was significantly reduced in ISA20-, ISA40-, ISA60-, ISA20-MFG2-, ISA40-MFG2-, and ISA60-MFG2-treated rabbits compared with that in MFG2-treated or UC rabbits (P < 0.01). Measures of organism-mediated pulmonary injury, lung weights, and pulmonary infarct score were lower in ISA40-MFG2-treated rabbits than in rabbits treated with ISA40 or MFG2 alone (P < 0.01). Survival was prolonged in ISA40-MFG2-treated rabbits in comparison to those treated with ISA40 or MFG2 alone (P < 0.01). These outcome variables correlated directly with significant declines in GMI and serum (1→3)-β-d-glucan levels during therapy. The GMI correlated with measures of organism-mediated pulmonary injury, lung weights (r = 0.764; P < 0.001), and pulmonary infarct score (r = 0.911; P < 0.001). In summary, rabbits receiving combination therapy with isavuconazole and micafungin demonstrated a significant dose-dependent reduction in the residual fungal burden, decreased pulmonary injury, prolonged survival, a lower GMI, and lower serum (1→3)-β-d-glucan levels in comparison to rabbits receiving isavuconazole or micafungin as a single agent.

Two Phase 1, Open-Label, Mass Balance Studies to Determine the Pharmacokinetics of 14 C-Labeled Isavuconazonium Sulfate in Healthy Male Volunteers

Isavuconazonium sulfate is the water‐soluble prodrug of the active triazole isavuconazole. Two phase 1 studies were conducted to identify the metabolic profile and mass balance of isavuconazole and BAL8728 (inactive cleavage product). Seven subjects in study 1 (isavuconazole mass balance) received a single oral dose of [cyano‐¹⁴C]isavuconazonium sulfate corresponding to 200 mg isavuconazole. Six subjects in study 2 (BAL8728 mass balance) received a single intravenous dose of [pyridinylmethyl‐¹⁴C]isavuconazonium sulfate corresponding to 75 mg BAL8728. Pharmacokinetic parameters of radioactivity in whole blood and plasma and of isavuconazole and BAL8728 in plasma were assessed. Radioactivity ratio of blood/plasma, percentage of dose, and cumulative percentage of radioactive dose recovered in urine and feces for isavuconazole and BAL8728 were assessed. Metabolic profiling was carried out by high‐performance liquid chromatography and mass spectrometry. Mean plasma isavuconazole pharmacokinetic parameters included apparent clearance (2.3 ± 0.7 L/h), apparent volume of distribution (301.8 ± 105.7 L), and terminal elimination half‐life (99.9 ± 44.6 hours). In study 1, isavuconazole‐derived radioactivity was recovered approximately equally in urine and feces (46.1% and 45.5%, respectively). In study 2, BAL8728‐derived radioactivity was predominantly recovered in urine (96.0%). Isavuconazole (study 1) and M4 (cleavage metabolite of BAL8728; study 2) were the predominant circulating components of radioactivity in plasma.

Gastroesophageal Reflux Disease and Pulmonary Diseases Associated with Aspergillosis: Is There a Connection?

INTRODUCTION

We studied the relationship between GORD and allergic bronchopulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis (CPA), or Aspergillus bronchitis.

BACKGROUND

Gastroesophageal reflux disease (GORD) is well known to initiate or exacerbate pulmonary inflammatory conditions, inducing bronchial asthma and chronic obstructive lung disease.

METHODS

We reviewed four patients referred with elevated Aspergillus serology markers and marked pulmonary symptoms for ABPA, CPA, and Aspergillus bronchitis, and discussed the underlying pathophysiological relationship with GORD. Data were collected retrospectively from medical records included age, gender, predisposing factors for ABPA, chronic pulmonary aspergillosis, or Aspergillus bronchitis; presence of nocturnal reflux, nausea, epigastric pain, Medical Research Council dyspnea scale score, pH manometry data, endoscopic results (ulcers, Barrett's esophagus), treatment of GORD [proton-pump inhibitors (PPIs), surgical operation]; history of smoking, alcohol consumption; concomitant COPD; serological markers (anti-Aspergillus IgG, anti-Aspergillus IgE), and antifungal treatment.

RESULTS

Four patients with GORD were studied; following PPIs administration two achieved clinical improvement. One had ABPA, one CPA, and two had Aspergillus bronchitis; median age was 57 years [range 39-71]; males-to-females ratio was 1:3. Serological markers for aspergillosis were: median total IgE antibodies 573 KIU/L [range 13.1-850], median Aspergillus IgE-specific antibodies 1.2 kAU/L [range <0.4-24.7], and median Aspergillus IgG titers 71 mg/L [range 20-119]. Aspergillus fumigatus grew in one sputum sample.

CONCLUSION

Clinicians caring for patients with gastroesophageal reflux disease presenting with elevated Aspergillus IgG or IgE antibodies should maintain a high index of suspicion for this association and proceed to appropriate evaluations, including laryngoscopy and endoscopy, initiating specific PPI-directed therapy when indicated.

Pharmacokinetics of antifungal drugs: practical implications for optimized treatment of patients

Introduction

Because of the high mortality of invasive fungal infections (IFIs), appropriate exposure to antifungals appears to be crucial for therapeutic efficacy and safety.

Materials and methods

This review summarises published pharmacokinetic data on systemically administered antifungals focusing on co-morbidities, target-site penetration, and combination antifungal therapy.

Conclusions and discussion

Amphotericin B is eliminated unchanged via urine and faeces. Flucytosine and fluconazole display low protein binding and are eliminated by the kidney. Itraconazole, voriconazole, posaconazole and isavuconazole are metabolised in the liver. Azoles are substrates and inhibitors of cytochrome P450 (CYP) isoenzymes and are therefore involved in numerous drug–drug interactions. Anidulafungin is spontaneously degraded in the plasma. Caspofungin and micafungin undergo enzymatic metabolism in the liver, which is independent of CYP. Although several drug–drug interactions occur during caspofungin and micafungin treatment, echinocandins display a lower potential for drug–drug interactions. Flucytosine and azoles penetrate into most of relevant tissues. Amphotericin B accumulates in the liver and in the spleen. Its concentrations in lung and kidney are intermediate and relatively low myocardium and brain. Tissue distribution of echinocandins is similar to that of amphotericin. Combination antifungal therapy is established for cryptococcosis but controversial in other IFIs such as invasive aspergillosis and mucormycosis.

New pharmacological opportunities for the treatment of invasive mould diseases

Recently, several randomized studies have been published that will shape treatment decisions in the prevention and management of invasive mould infections. Liposomal amphotericin B is an option for empirical or targeted treatment of invasive aspergillosis or mucormycosis, but for prophylaxis therapy, the triazole class now predominates. The triazole voriconazole is currently regarded as a drug of choice for the treatment of proven or probable invasive aspergillosis, and has shown significantly higher response rates than amphotericin B deoxycholate in this setting, with fewer severe drug-related adverse events. Isavuconazole, the newest triazole agent, offers the advantages of once-daily dosing, a wider spectrum of antifungal activity than voriconazole, predictable pharmacokinetics and fewer CYP enzyme-mediated drug interactions. A recent large randomized clinical trial showed mortality to be similar under isavuconazole or voriconazole in patients with invasive mould disease, with fewer drug-related adverse events in isavuconazole-treated patients. Another study has indicated that isavuconazole is also effective in mucormycosis infections but patient numbers were small and confirmation is awaited. Experimental studies combining different drug classes with antimould activity have been promising, but the clinical database is limited. A large randomized trial of combination therapy compared voriconazole plus the echinocandin anidulafungin versus voriconazole monotherapy in patients with invasive aspergillosis. Results showed the overall response rate to be similar, but combination therapy improved survival for the subpopulation of patients in whom the diagnosis was confirmed by serum and/or bronchoalveolar lavage fluid galactomannan positivity. This active field of research is likely to continue evolving rapidly in the coming years.

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.

Special considerations for the diagnosis and treatment of invasive pulmonary aspergillosis

INTRODUCTION

The diagnosis and treatment of invasive pulmonary aspergillosis (IPA) are ongoing challenges in clinical practice. While important advances have recently been made, including enhanced diagnostic modalities as well as novel therapeutic and prophylactic options, more effective options are urgently needed as the population of immunocompromised patients continues to expand. Areas covered: In this paper, we review novel approaches to diagnosis of IPA, including multiplex PCR, Matrix Assisted Laser Desorption/Ionization-Time of Flight Mass Spectrometry and provide a detailed review of the extended-spectrum triazole isavuconazole, which was approved in 2015 to treat IPA. Expert commentary: We explore burgeoning approaches to diagnosis, including the lateral flow assay, volatile organic compounds, and artificial olfactory technology, as well as novel antifungal agents to treat IPA such as SCY-078 and F901318.

Overview of Treatment Approaches for Fungal Infections

Invasive fungal diseases cause high morbidity and mortality in an immunocompromised host. Antifungals are the drugs of choice and can be divided into 4 main groups: polyenes, azoles, echinocandins, and pyrimidine analogues. Each class has its specific mechanism of action, spectrum of activity, and pharmacokinetic and side effects. It is important to understand the precise use of the established and new antifungal agents to successfully manage these complex infections in an already tenuous and frail host. This article discusses the main characteristics, clinical uses, and secondary effects of the main antifungals used in clinical practice.

Susceptibility Testing of Common and Uncommon Aspergillus Species against Posaconazole and Other Mold-Active Antifungal Azoles Using the Sensititre Method

We tested 59 common and 27 uncommon Aspergillus species isolates for susceptibility to the mold-active azole antifungal agents itraconazole, voriconazole, and posaconazole using the Sensititre method. The overall essential agreement with the CLSI reference method was 96.5% for itraconazole and posaconazole and was 100% for voriconazole. By the Sensititre method as well as the CLSI reference method, all of 10 A. fumigatus isolates with a cyp51 mutant genotype were classified as being non-wild-type isolates (MIC > epidemiological cutoff value [ECV]) with respect to triazole susceptibility.

Triazole Resistance in Aspergillus Species: An Emerging Problem

Aspergillus species are ubiquitous fungal saprophytes found in diverse ecological niches worldwide. Among them, Aspergillus fumigatus is the most prevalent and is largely responsible for the increased incidence of invasive aspergillosis with high mortality rates in some immunocompromised hosts. Azoles are the first-line drugs in treating diseases caused by Aspergillus spp. However, increasing reports in A. fumigatus azole resistance, both in the clinical setting and in the environment, are threatening the effectiveness of clinical and agricultural azole drugs. The azole target is the 14-α sterol demethylase encoded by cyp51A gene and the main mechanisms of resistance involve the integration of tandem repeats in its promoter and/or single point mutations in this gene. In A. fumigatus, azole resistance can emerge in two different scenarios: a medical route in which azole resistance is generated during long periods of azole treatment in the clinical setting and a route of resistance derived from environmental origin due to extended use of demethylation inhibitors in agriculture. The understanding of A. fumigatus azole resistance development and its evolution is needed in order to prevent or minimize its impact. In this article, we review the current situation of azole resistance epidemiology and the predominant molecular mechanisms described based on the resistance acquisition routes. In addition, the clinical implications of A. fumigatus azole resistance and future research are discussed.

Antifungal drug testing by combining minimal inhibitory concentration testing with target identification by gas chromatography-mass spectrometry

Fungal infections and their increasing resistance to antibiotics are an emerging threat to public health. Novel antifungal drugs, as well technologies that can help us bolster the antimicrobial pipeline and understand resistance mechanisms, are needed. The ergosterol biosynthetic pathway is one potential target for antifungal drugs. Here we describe how antifungal susceptibility testing can be combined with target identification in distal ergosterol biosynthesis by means of gas chromatography-mass spectrometry. The fungi are treated with sublethal doses of active components that block ergosterol biosynthesis, and the ergosterol biosynthesis intermediates are analyzed in a targeted metabolomics manner after derivatization (trimethylsilylation). Drug treatment results in distinct sterol patterns that are characteristic of the affected enzyme. Sterol identification based on relative retention times and electron ionization (EI) mass spectra, as well as semiquantitative assessment of ergosterol intermediates, is described. The protocol is applicable to yeasts and molds. The overall analysis time from incubation to test result is not more than 3 d. The assay can be used to determine whether an antifungal compound of interest targets sterol biosynthesis, and, if so, to determine which enzyme in the pathway it targets.

Phase I trial to investigate the effect of renal impairment on isavuconazole pharmacokinetics

Purpose

The purpose of the study is to evaluate the effect of renal impairment (RI) and end-stage renal disease (ESRD) on the pharmacokinetics (PK) of isavuconazole and the inactive cleavage product, BAL8728.

Methods

A single intravenous dose of the prodrug isavuconazonium sulfate (372 mg, equivalent to 200 mg isavuconazole and 75 mg of BAL8728 cleavage product) was administered to healthy controls (parts 1 and 2) and participants with mild, moderate, or severe RI (part 2) or ESRD (part 1); ESRD participants received two doses of 200 mg isavuconazole, 1 h post-dialysis (day 1) and prior to dialysis (day 15). Plasma PK parameters for isavuconazole included maximum concentration (C_max), area under the concentration–time curve (AUC) from time of dose to 72 h (AUC₇₂), AUC extrapolated to infinity (AUC_∞), AUC to last measurable concentration (AUC_last), half-life (t_½ h), volume of distribution (V_z), and total clearance (CL), for the healthy control group versus those with mild, moderate, or severe RI or ESRD.

Results

Isavuconazole C_max values were 4% higher in mild RI and 7, 14, and 21% lower in participants with moderate RI, severe RI, or ESRD versus the healthy control group, respectively. When hemodialysis occurred post-dose (day 15), participants with ESRD had a 30% increase in AUC₇₂ for isavuconazole in parallel with reduction of extracellular volume induced by dialysis. Exposure (AUC_∞ and AUC_last) was not significantly different for participants with mild, moderate, or severe RI versus healthy controls although there was considerable variability. The t_1/2 (day 1) was 125.5 ± 63.6 h (healthy control group), 204.5 ± 82.6 h (ESRD group) in part 1, and 140.5 ± 77.7 h (healthy control group), 117.0 ± 66.2 h (mild RI), 158.5 ± 56.4 h (moderate RI), and 145.8 ± 65.8 L/h (severe RI) in part 2. CL was 2.4 ± 0.8 L/h (healthy control group) and 2.9 ± 1.3 L/h (ESRD group) in part 1 and 2.4 ± 1.2 L/h (healthy control group), 2.5 ± 1.0 L/h (mild RI), 2.2 ± 0.8 L/h (moderate RI), and 2.4 ± 0.8 L/h (severe RI) in part 2. The V_z was 382.6 ± 150.6 L in the healthy control group and 735.6 ± 277.3 L in ESRD patients on day 1 in part 1 of the study. In part 2 of the study, V_z was 410.8 ± 89.7 L in the healthy control group, 341.6 ± 72.3 L in mild RI, 509.1 ± 262.2 L in moderate RI, and 439.4 L in severe RI.

Conclusions

Based on the findings of this study, dose adjustments of isavuconazole are unlikely to be required in individuals with RI or in those with ESRD who receive hemodialysis.

Electronic supplementary material

The online version of this article (doi:10.1007/s00228-017-2213-7) contains supplementary material, which is available to authorized users.

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.

An update on the safety and interactions of antifungal drugs in stem cell transplant recipients

INTRODUCTION

Invasive fungal diseases (IFDs) are a major cause of morbidity and mortality in patients undergoing allogeneic hematopoietic stem cell transplant (HSCT). Improvement in the management of IFDs have been achieved with the availability of new effective and safe antifungal drugs, however, many of these newer treatments have some limitations in their variable toxicity and unique predisposition for pharmacokinetic drug-drug interactions. Areas covered: This article is an update of a previous review published in this journal evaluating the safety profile of the antifungal drugs. Interesting new features include the availability of the new drug isavuconazole and the new tablet and intravenous formulations of posaconazole. Different dosages and new ways of administration of liposomal Amphotericin B (L-AmB) and echinocandins may be considered in the HSCT practice. Expert opinion: Nephrotoxicity continues to be a clinically relevant and frequent side effect of L-AmB which may cause a reduced clearance of other renally eliminated drugs frequently used in HSCT patients. Echinocandins are favorable therapeutic options in view of their low toxicity and uncommon drug-drug interactions. Important limitations of triazoles are represented by hepatic toxicity and certain side effects particularly after prolonged treatments. The new triazole isavuconazole and the new tablet formulation of posaconazole will be probably increasingly used in the HSCT setting not only due to their efficacy but in particular for their interesting toxicity profile and pharmacokinetic characteristics. The knowledge of these pharmacological findings is crucial in the daily care of allogeneic HSCT patients.

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.

Fungal skin and soft tissue infections

PURPOSE OF REVIEW

Cutaneous and subcutaneous mycoses are a source of significant morbidity both in immunocompetent and immunocompromised patients. We here review the latest findings in terms of genetic predisposition, epidemiology, clinical manifestations, and therapeutic strategies in these diseases.

RECENT FINDINGS

A growing number of fungal skin and soft tissue infections are reported worldwide. In immunocompromised patients, these infections are often associated with disseminated disease. Skin and soft tissue biopsies usually allow mycological identification. Although tissue culture remains the gold standard, molecular biology is increasingly used and sometimes mandatory for accurate diagnosis. Advances in therapeutics have improved outcome and lowered dissemination risk in patients.

SUMMARY

Cutaneous and subcutaneous mycoses are an evolving field. Clinicians all over the world should be aware of the common manifestations of these diseases - infectious diseases - as they are increasingly reported and may lead to or be associated with dissemination.

Invasive Aspergillosis: Current Strategies for Diagnosis and Management

Aspergillosis remains a significant cause of morbidity and mortality in the immunocompromised population. The spectrum of disease is broad, ranging from severe and rapidly fatal infection to noninvasive disease. The diversity of patients and risk factors complicates diagnostic and therapeutic decision-making. Invasive procedures are often precluded by host status; noninvasive diagnostic tests vary in their sensitivity and specificity. Advancements in understanding the pathophysiology of invasive aspergillosis and host genetics in differential risk have also occurred. Future work may assist in therapeutic decision-making and patient prognosis. Voriconazole remains the preferred agent for treatment. Additional alternatives have emerged.

In Vitro Activity of Isavuconazole against Rasamsonia Species

The in vitro susceptibilities to the novel triazole isavuconazole and six other antifungal agents of a large collection of Rasamsonia isolates (n = 47) belonging to seven species were determined. Isavuconazole and voriconazole had no in vitro activity (MIC, >32 mg/liter) against isolates of the Rasamsonia argillacea species complex. The echinocandins were the most potent antifungal drugs against all of the isolates tested (minimum effective concentration, ≤0.19 mg/liter).

Regulatory Pathways for New Antimicrobial Agents: Trade-offs to Keep the Perfect From Being the Enemy of the Good

In 2002, Shlaes and Moellering warned that pharmaceutical companies were abandoning antibiotic research and development due to changing regulatory standards regarding noninferiority (NI) clinical trials. NI trials are subject to unique biases that may yield false-positive conclusions. The US Food and Drug Administration (FDA) developed guidance to ensure that NI results truly reflect drug efficacy. These changes, intended to reduce uncertainty in trial results, have shaped trial enrollment and conduct in ways that now require reflection.

Antifungal Drugs: The Current Armamentarium and Development of New Agents

Invasive fungal infections are becoming an increasingly important cause of human mortality and morbidity, particularly for immunocompromised populations. The fungal pathogens Candida albicans , Cryptococcus neoformans , and Aspergillus fumigatus collectively contribute to over 1 million human deaths annually. Hence, the importance of safe and effective antifungal therapeutics for the practice of modern medicine has never been greater. Given that fungi are eukaryotes like their human host, the number of unique molecular targets that can be exploited for drug development remains limited. Only three classes of molecules are currently approved for the treatment of invasive mycoses. The efficacy of these agents is compromised by host toxicity, fungistatic activity, or the emergence of drug resistance in pathogen populations. Here we describe our current arsenal of antifungals and highlight current strategies that are being employed to improve the therapeutic safety and efficacy of these drugs. We discuss state-of-the-art approaches to discover novel chemical matter with antifungal activity and highlight some of the most promising new targets for antifungal drug development. We feature the benefits of combination therapy as a strategy to expand our current repertoire of antifungals and discuss the antifungal combinations that have shown the greatest potential for clinical development. Despite the paucity of new classes of antifungals that have come to market in recent years, it is clear that by leveraging innovative approaches to drug discovery and cultivating collaborations between academia and industry, there is great potential to bolster the antifungal armamentarium.

Delaying diagnostic procedure significantly increases mortality in patients with invasive mucormycosis

Invasive mucormycosis is an uncommon but increasing life-threatening fungal infection. The present study investigated clinical characteristics and mortality among patients diagnosed as invasive mucormycosis infection. We retrospectively reviewed a total of 24 histologically proven cases of invasive mucormycosis at two tertiary care referral hospitals between November 2005 and February 2014. Overall survival was 50% (n = 12). The time between onset of symptom and diagnostic procedure proved to be associated with mortality (P = 0.009). In addition, preexisting renal failure and thrombocytopenia demonstrated trends toward a poor outcome in our study (P = 0.089 and 0.065, respectively). On multivariate regression analysis, delayed diagnostic procedure (more than 16 days after the onset of symptoms) was an independent predictor of mortality (OR= 12.34, 95% CI, 1.43-10.64; P = 0.022). Mucormycosis is a destructive fungal infection that is associated with high mortality rates, ranging from 40% to 100% depending on the form of disease. When a clinician suspects invasive mucormycosis infection, an early diagnostic procedure performed within 16 days from the onset of symptom and early initiation of antifungal therapy will lead to successful management of this highly fatal disease.

Cutaneous mucormycosis in advanced HIV disease

Angionvasive mucormycosis is an emerging fungal disease known to affect mainly diabetics or subjects with profound neutropenia. Infection usually occurs through the inhalation route, but cutaneous inoculation may occur after trauma or burns. However, mucormycosis remains unusual in HIV infection. We report a fatal case of cutaneous mucormycosis due to Rhizopus arrhizus involving the scalp following herpes zoster infection. The patient was a 42-year-old man with advanced AIDS failing on salvage antiretroviral therapy. The fungus was diagnosed on the basis of histopathology and culture. Our case emphasizes the need to consider mucormycosis in the differential diagnosis of necrotic cutaneous lesions in patients with late-stage HIV disease.

Pharmacokinetic Evaluation of CYP3A4-Mediated Drug-Drug Interactions of Isavuconazole With Rifampin, Ketoconazole, Midazolam, and Ethinyl Estradiol/Norethindrone in Healthy Adults

This report describes the phase 1 trials that evaluated the metabolism of the novel triazole antifungal isavuconazole by cytochrome P450 3A4 (CYP3A4) and isavuconazole's effects on CYP3A4‐mediated metabolism in healthy adults. Coadministration of oral isavuconazole (100 mg once daily) with oral rifampin (600 mg once daily; CYP3A4 inducer) decreased isavuconazole area under the concentration‐time curve (AUC_τ) during a dosing interval by 90% and maximum concentration (C_max) by 75%. Conversely, coadministration of isavuconazole (200 mg single dose) with oral ketoconazole (200 mg twice daily; CYP3A4 inhibitor) increased isavuconazole AUC from time 0 to infinity (AUC_0‐∞) and C_max by 422% and 9%, respectively. Isavuconazole was coadministered (200 mg 3 times daily for 2 days, then 200 mg once daily) with single doses of oral midazolam (3 mg; CYP3A4 substrate) or ethinyl estradiol/norethindrone (35 μg/1 mg; CYP3A4 substrate). Following coadministration, AUC_0‐∞ increased 103% for midazolam, 8% for ethinyl estradiol, and 16% for norethindrone; C_max increased by 72%, 14%, and 6%, respectively. Most adverse events were mild to moderate in intensity; there were no deaths, and serious adverse events and adverse events leading to study discontinuation were rare. These results indicate that isavuconazole is a sensitive substrate and moderate inhibitor of CYP3A4.