Role of isavuconazole in the treatment of invasive fungal infections

Therapeutic drug monitoring-guided high-dose isavuconazole therapy for invasive pulmonary aspergillosis in a patient on extracorporeal membrane oxygenation support

We review the case of a 58-year-old female on extracorporeal membrane oxygenation (ECMO) support diagnosed with invasive pulmonary aspergillosis (IPA). Intravenous isavuconazole was started, requiring dose escalation to achieve isavuconazole trough concentration (ISA-Cmin) within the therapeutic range (2.5-5.0 μg/mL). For more than 4 months, she maintained a dose of 200 mg q12h, with a median ISA-Cmin of 3.4 (interquartile range [IQR]: 3.1-4.9) µg/mL. Throughout this interval, 17 assessments of ISA-Cmin were performed (weekly). Of these, 82% (14/17) were within the therapeutic range, with an intra-individual variability of 36.8%. Although no signs of hepatotoxicity were observed, she experienced short-term gastrointestinal adverse events related to potential isavuconazole over-exposure (ISA-Cmin > 5.0 μg/mL). ECMO circuit changes did not appear to affect ISA-Cmin. She was not obese (IMC ≈ 25 kg/m2) and did not require other extracorporeal therapy, but hypoalbuminemia may have contributed to an increase in unbound isavuconazole fraction and consequently its clearance.

Search for novel Plasmodium falciparum PfATP4 inhibitors from the MMV Pandemic Response Box through a virtual screening approach

Owing to its life cycle involving multiple hosts and species-specific biological complexities, a vaccine against Plasmodium, the causative agent of Malaria remains elusive. This makes chemotherapy the only viable means to address the clinical manifestations and spread of this deadly disease. However, rapid surge in antimalarial resistance poses significant challenges to our efforts to eliminate Malaria since the best drug available to-date; Artemisinin and its combinations are also rapidly losing efficacy. Sodium ATPase (PfATP4) of Plasmodium has been recently explored as a suitable target for new antimalarials such as Cipargamin. Prior studies showed that multiple compounds from the Medicines for Malaria Venture (MMV) chemical libraries were efficient PfATP4 inhibitors. In this context, we undertook a structure- based virtual screening approach combined to Molecular Dynamic (MD) simulations to evaluate whether new molecules with binding affinity towards PfATP4 could be identified from the Pandemic Response Box (PRB), a 400-compound library of small molecules launched in 2019 by MMV. Our analysis identified new molecules from the PRB library that showed affinity for distinct binding sites including the previously known G358 site, several of which are clinically used anti-bacterial (MMV1634383, MMV1634402), antiviral (MMV010036, MMV394033) or antifungal (MMV1634494) agents. Therefore, this study highlights the possibility of exploiting PRB molecules against Malaria through abrogation of PfATP4 activity.Communicated by Ramaswamy H. Sarma.

Genomic and computational-aided integrative drug repositioning strategy for EGFR and ROS1 mutated NSCLC

Non-small cell lung cancer (NSCLC) has been marked as the major cause of death in lung cancer patients. Due to tumor heterogeneity, mutation burden, and emerging resistance against the available therapies in NSCLC, it has been posing potential challenges in the therapy development. Hence, identification of cancer-driving mutations and their effective inhibition have been advocated as a potential approach in NSCLC treatment. Thereof, this study aims to employ the genomic and computational-aided integrative drug repositioning strategy to identify the potential mutations in the selected molecular targets and repurpose FDA-approved drugs against them. Accordingly, molecular targets and their mutations, i.e., EGFR (V843L, L858R, L861Q, and P1019L) and ROS1 (G1969E, F2046Y, Y2092C, and V2144I), were identified based on TCGA dataset analysis. Following, virtual screening and redocking analysis, Elbasvir, Ledipasvir, and Lomitapide drugs for EGFR mutants (>-10.8 kcal/mol) while Indinavir, Ledipasvir, Lomitapide, Monteleukast, and Isavuconazonium for ROS1 mutants (>-8.8 kcal/mol) were found as putative inhibitors. Furthermore, classical molecular dynamics simulation and endpoint binding energy calculation support the considerable stability of the selected docked complexes aided by substantial hydrogen bonding and hydrophobic interactions in comparison to the respective control complexes. Conclusively, the repositioned FDA-approved drugs might be beneficial alone or in synergy to overcome acquired resistance to EGFR and ROS1-positive lung cancers.

A Silent Threat Unveiled: Invasive Fungal Sinusitis in a High-Risk Hematologic Malignancy Patient

Invasive fungal sinusitis (IFS) poses a fatal threat to patients with hematological malignancies or a history of allogeneic hematopoietic stem cell transplant (HSCT). While invasive aspergillosis, a subtype of IFS, remains rare in immunocompetent individuals, allogeneic HSCT recipients face a notable surge in incidence. Despite the rapid onset and progression of IFS, its clinical presentation is subtle, contributing to heightened mortality rates. Prompt surgical debridement and systemic antifungal therapy are required to yield positive results. Examining IFS cases in HSCT recipients is vital, providing insights into its clinical course, prevention strategies, and improved evaluation. We present a rare presentation of IFS with Aspergillus niger in a relapsed acute myeloid leukemia patient post-HSCT. Two weeks after chemotherapy, the patient developed headaches and blood-tinged sinus drainage in the setting of pancytopenia. Radiologic and pathological findings confirmed the diagnosis of IFS, necessitating weeks of intensive anti-fungal therapy. Despite the initial positive response, the disease ultimately progressed to a fatal outcome. This case emphasizes that early detection is required for a favorable treatment response. Furthermore, it underscores the importance of heightened clinical suspicion, risk stratification, multidisciplinary care, and ongoing research for optimal management of IFS in allogeneic HSCT recipients.

Coadministration of isavuconazole and sirolimus in allogeneic hematopoietic stem cell transplant recipients

Background

Invasive fungal infections (IFIs) represent a major cause of morbidity among allogeneic hematopoietic stem cell transplantation (allo-HSCT). Isavuconazole (ISA) is a broad-spectrum triazole with favorable safety profile.

Objectives and design

Herein, we evaluate the real life coadministration of ISA and sirolimus in allo-HSCT recipients in a single-center retrospective analysis, describing clinical efficacy, safety, and therapeutic drug monitoring (TDM) of both drugs.

Methods

All consecutive allo-HSCT recipients who received the coadministration of ISA and sirolimus for at least 2 weeks between July 2017 and December 2022 were included in this retrospective analysis. TDM was longitudinally performed during treatment. IFIs were classified according to the revised European Organization for Research and Treatment of Cancer/Mycoses Study Group consensus criteria.

Results

A total of 51 recipients were included in the analysis. A total of 17 patients received ISA as continuous antifungal treatment for IFI diagnosed before transplant: one patient experienced a probable invasive pulmonary aspergillosis, and one patient switched from ISA to liposomal amphotericin B for a possible IFI. A total of 34 patients started ISA as antifungal therapy for IFI diagnosed after transplant. Sixteen of 34 were treated for a proven/probable breakthrough IFI during mold-active prophylaxis: 6/16 patients died for IFI after a median of 51 days of ISA. Eighteen of 34 started ISA as empirical therapy for a possible IFI: 15/18 patients were alive with resolution of infection after 6 weeks, 1 died for disease progression, and 2 had empirically changed antifungal therapy due to pneumonia progression. Clinical and radiological response rate was 68% after 90 days from IFI diagnosis. No toxicities related to drug-drug interaction have been registered in patients reaching concomitant therapeutic levels of ISA and sirolimus.

Conclusion

The coadministration of ISA and sirolimus was safe and feasible in this cohort, confirming favorable clinical efficacy in patients with multiple-drug coadministration.

Pharmacoeconomic evaluation of isavuconazole, posaconazole, and voriconazole for the treatment of invasive mold diseases in hematological patients: initial therapy prior to pathogen differential diagnosis in China

Background

Invasive mold diseases (IMD) is associated with high mortality and a substantial economic burden. For high-risk patients, fever drive or diagnostic drive therapy is usually initiated prior to the differential diagnosis of the pathogen. This study evaluated the cost-effectiveness of isavuconazole, posaconazole, vs. voriconazole in the treatment of IMD from the perspective of the Chinese healthcare system, informing healthcare decision-making and resource allocation.

Methods

A decision analytic model was constructed using TreeAge Pro 2011 software to evaluate the cost-effectiveness of the entire disease course. We assumed that the prevalence of mucormycosis in the patients entering the model was 7.8%. Efficacy, cost, adverse events, and other data included in the model were mainly derived from clinical studies, published literature, and publicly available databases. The primary outcomes of the model output were total cost, quality-adjusted life years (QALYs), life years (Lys), and incremental cost-effectiveness ratio (ICER). The willing-to-pay (WTP) threshold was defined as one to three times China's GDP per capita in 2022. One-way sensitivity analysis and probability sensitivity analysis were used to determine the robustness of the model. At the same time, the cost-effectiveness of three triazole antifungal agents under a broader range of mucormycosis prevalence, when voriconazole was covered by medical insurance reimbursement, and after the price reduction of posaconazole was discussed.

Results

Compared with voriconazole, isavuconazole provided an additional 0.38 Lys (9.29 vs. 8.91 LYs) and 0.31 QALYs (7.62 vs. 7.31 QALYs); ICER was $15,702.46/QALY, well-below the WTP threshold ($38,223/QALY). However, posaconazole did not provide a significant economic advantage over voriconazole (9.40 vs. 9.36 Lys; 7.71 vs. 7.68 QALYs; ICER $64,466.57/QALY). One-way sensitivity analysis found that ICER was highly sensitive to the mortality of patients with invasive aspergillus infection. In the probabilistic sensitivity analysis, when the WTP threshold was $38,223/QALY, the probability of isavuconazole being cost-effective was 72.9%. The scenario analysis results indicated that posaconazole would become cost-effective when the price was reduced by 15% or the prevalence of mucormycosis was 14%.

Conclusions

Isavuconazole represents a cost-effective initial option for treating IMD in high-risk hematological patients prior to the differential diagnosis of pathogens. It will also be economical when a 15% reduction in posaconazole cost is achieved.

Breakthrough invasive fungal infections on isavuconazole prophylaxis in hematologic malignancy & hematopoietic stem cell transplant patients

BACKGROUND

Isavuconazole (ISA) is a newer antifungal used in patients with history of hematologic malignancies and hematopoietic transplant and cellular therapies (HM/TCT). Although it has a more favorable side-effect profile, breakthrough invasive fungal infections (bIFIs) while on ISA have been reported.

METHODS

In this single-center retrospective study evaluating HM/TCT patients who received prophylactic ISA for ≥7 days, we evaluated the incidence and potential risk factors for bIFIs.

RESULTS

We evaluated 106 patients who received prophylactic ISA. The patients were predominantly male (60.4%) with median age of 65 (range: 21-91) years. Acute myeloid leukemia (48/106, 45.3%) was the most common HM, with majority having relapsed and/or refractory disease (43/106, 40.6%) or receiving ongoing therapy (38/106, 35.8%). Nineteen patients (17.9%) developed bIFIs-nine proven [Fusarium (3), Candida (2), Mucorales plus Aspergillus (2), Mucorales (1), Colletotrichum (1)], four probable invasive pulmonary Aspergillus, and six possible infections. Twelve patients were neutropenic for a median of 28 (8-253) days prior to bIFI diagnosis. ISA levels checked within 7 days of bIFI diagnosis (median: 3.65 μg/mL) were comparable to industry-sponsored clinical trials. All-cause mortality among the bIFI cases was 47.4% (9/19).We also noted clinically significant cytomegalovirus co-infection in 5.3% (1/19). On univariate analysis, there were no significant differences in baseline comorbidities and potential risk factors between the two groups.

CONCLUSION

ISA prophylaxis was associated with a significant cumulative incidence of bIFIs. Despite the appealing side-effect and drug-interaction profile of ISA, clinicians must be vigilant about the potential risk for bIFIs.

Invasive Pulmonary Aspergillosis in Coronavirus Disease 2019 Patients Lights and Shadows in the Current Landscape

Invasive pulmonary aspergillosis (IPA) presents a known risk to critically ill patients with SARS-CoV-2; quantifying the global burden of IPA in SARS-CoV-2 is extremely challenging. The true incidence of COVID-19-associated pulmonary aspergillosis (CAPA) and the impact on mortality is difficult to define because of indiscriminate clinical signs, low culture sensitivity and specificity and variability in clinical practice between centers. While positive cultures of upper airway samples are considered indicative for the diagnosis of probable CAPA, conventional microscopic examination and qualitative culture of respiratory tract samples have quite low sensitivity and specificity. Thus, the diagnosis should be confirmed with serum and BAL GM test or positive BAL culture to mitigate the risk of overdiagnosis and over-treatment. Bronchoscopy has a limited role in these patients and should only be considered when diagnosis confirmation would significantly change clinical management. Varying diagnostic performance, availability, and time-to-results turnaround time are important limitations of currently approved biomarkers and molecular assays for the diagnosis of IA. The use of CT scans for diagnostic purposes is controversial due to practical concerns and the complex character of lesions presented in SARS-CoV-2 patients. The key objective of management is to improve survival by avoiding misdiagnosis and by initiating early, targeted antifungal treatment. The main factors that should be considered upon selection of treatment options include the severity of the infection, concomitant renal or hepatic injury, possible drug interactions, requirement for therapeutic drug monitoring, and cost of therapy. The optimal duration of antifungal therapy for CAPA is still under debate.

Studies on the inhibitory effect of isavuconazole on flumatinib metabolism in vitro and in vivo

As the validated agent for the treatment of chronic myelogenous leukemia (CML), flumatinib is a novel oral tyrosine kinase inhibitor (TKI) with higher potency and selectivity for BCR-ABL1 kinase compared to imatinib. Many patients experience aspergillosis infection and they may start using isavuconazole, which is an inhibitor of CYP3A4. However, there is no study on their interaction in vitro and in vivo. In the present study, the concentrations of flumatinib and its major metabolite M1 were rapidly determined using an stable ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method. The half-maximal inhibitory concentration (IC₅₀) was 6.66 μM in human liver microsomes (HLM), while 0.62 μM in rat liver microsomes (RLM) and 2.90 μM in recombinant human CYP3A4 (rCYP3A4). Furthermore, the mechanisms of inhibition of flumatinib in human liver microsomes, rat liver microsomes and rCYP3A4 by isavuconazole were mixed. Moreover, ketoconazole, posaconazole, and isavuconazole showed more potent inhibitory effects than itraconazole, fluconazole, and voriconazole on HLM-mediated flumatinib metabolism. In pharmacokinetic experiments of rats, it was observed that isavuconazole could greatly change the pharmacokinetic parameters of flumatinib, including AUC_(0-t), AUC_(0-∞), C_max and CLz/F, but had no effect on the metabolism of M1. According to the results of in vitro and in vivo studies, the metabolism of flumatinib was inhibited by isavuconazole, suggesting that isavuconazole may raise the plasma concentration of flumatinib. Thus, it is important to take special care of the interactions between flumatinib and isavuconazole in clinical applications.

Aspergillus Endophthalmitis: Epidemiology, Pathobiology, and Current Treatments

Fungal endophthalmitis is one of the leading causes of vision loss worldwide. Post-operative and traumatic injuries are major contributing factors resulting in ocular fungal infections in healthy and, more importantly, immunocompromised individuals. Among the fungal pathogens, the Aspergillus species, Aspergillus fumigatus, continues to be more prevalent in fungal endophthalmitis patients. However, due to overlapping clinical symptoms with other endophthalmitis etiology, fungal endophthalmitis pose a challenge in its diagnosis and treatment. Hence, it is critical to understand its pathobiology to develop and deploy proper therapeutic interventions for combating Aspergillus infections. This review highlights the different modes of Aspergillus transmission and the host immune response during endophthalmitis. Additionally, we discuss recent advancements in the diagnosis of fungal endophthalmitis. Finally, we comprehensively summarize various antifungal regimens and surgical options for the treatment of Aspergillus endophthalmitis.

Multicenter Registry of Patients Receiving Systemic Mold-Active Triazoles for the Management of Invasive Fungal Infections

Introduction

‘Real-world’ data for mold-active triazoles (MATs) in the treatment of invasive fungal infections (IFIs) are lacking. This study evaluated usage of MATs in a disease registry for the management of IFIs.

Methods

Data were collected for this multicenter, observational, prospective study from 55 US centers, between March 2017 and April 2020. Eligible patients received isavuconazole, posaconazole, or voriconazole as MAT monotherapy (one MAT) or multiple/sequenced MAT therapy (more than one MAT) for prophylaxis or treatment. Patients were enrolled within 60 days of MAT initiation. The primary objective was to characterize patients receiving a MAT and their patterns of therapy. The full analysis set (FAS) included eligible patients for the relevant enrollment protocol, and the safety analysis set (SAF) included patients who received ≥ 1 MAT dose.

Results

Overall, 2009 patients were enrolled in the SAF. The FAS comprised 1993 patients (510 isavuconazole; 540 posaconazole; 491 voriconazole; 452 multiple/sequenced MAT therapies); 816 and 1177 received treatment and prophylaxis at study index/enrollment, respectively. Around half (57.8%) of patients were male, and median age was 59 years. Among patients with IFIs during the study, the most common pathogens were Aspergillus fumigatus in the isavuconazole (18.2% [10/55]) and voriconazole (25.5% [12/47]) groups and Candida glabrata in the posaconazole group (20.9% [9/43]); the lungs were the most common infection site (58.2% [166/285]). Most patients were maintained on MAT monotherapy (77.3% [1541/1993]), and 79.4% (1520/1915) completed their MAT therapies. A complete/partial clinical response was reported in 59.1% (591/1001) of patients with a clinical response assessment. Breakthrough IFIs were reported in 7.1% (73/1030) of prophylaxis patients. Adverse drug reactions (ADRs) were reported in 14.7% (296/2009) of patients (3.9% [20/514] isavuconazole; 11.3% [62/547] posaconazole; 14.2% [70/494] voriconazole).

Conclusions

In this ‘real-world’ study, most patients remained on their initial therapy and completed their MAT therapy. Over half of patients receiving MATs for IFIs had a successful response, and most receiving prophylaxis did not develop breakthrough IFIs. ADRs were uncommon.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-022-00661-5.

Pharmacokinetics of isavuconazole in healthy cats after oral and intravenous administration

Background

Isavuconazole is a triazole antifungal drug that has shown good efficacy in human patients. Absorption and pharmacokinetics have not been evaluated in cats.

Objectives

To determine the pharmacokinetics of isavuconazole in cats given a single IV or PO dose.

Animals

Eight healthy, adult research cats.

Methods

Four cats received 100 mg capsules of isavuconazole PO. Four cats received 5 mg/kg isavuconazole solution IV. Serum was collected at predetermined intervals for analysis using ultra‐high performance liquid chromatography‐tandem mass spectrometry. Data were analyzed using a 2‐compartment uniform weighting pharmacokinetic analysis with lag time for PO administration and a 2 compartment, 1/y² weighting for IV administration. Predicted 24 and 48‐hour dosing intervals of 100 mg isavuconazole administered PO were modeled and in vitro plasma protein binding was assessed.

Results

Both PO and IV drug administration resulted in high serum concentrations. Intravenous and PO formulations of isavuconazole appear to be able to be used interchangeably. Peak serum isavuconazole concentrations occurred 5 ± 3.8 hours after PO administration with an elimination rate half‐life of 66.2 ± 55.3 hours. Intersubject variability was apparent in both the PO and IV groups. Two cats vomited 6 to 8 hours after PO administration. No adverse effects were observed in the IV group. Oral bioavailability was estimated to be approximately 88%. Serum protein binding was calculated to be approximately 99.0% ± 0.03%.

Conclusions and Clinical Importance

Isavuconazole might prove to be useful in cats with fungal disease given its favorable pharmacokinetics. Additional studies on safety, efficacy, and tolerability of long‐term isavuconazole use are needed.

The Overview on the Pharmacokinetic and Pharmacodynamic Interactions of Triazoles

Second generation triazoles are widely used as first-line drugs for the treatment of invasive fungal infections, including aspergillosis and candidiasis. This class, along with itraconazole, voriconazole, posaconazole, and isavuconazole, is characterized by a broad range of activity, however, individual drugs vary considerably in safety, tolerability, pharmacokinetics profiles, and interactions with concomitant medications. The interaction may be encountered on the absorption, distribution, metabolism, and elimination (ADME) step. All triazoles as inhibitors or substrates of CYP isoenzymes can often interact with many drugs, which may result in the change of the activity of the drug and cause serious side effects. Drugs of this class should be used with caution with other agents, and an understanding of their pharmacokinetic profile, safety, and drug-drug interaction profiles is important to provide effective antifungal therapy. The manuscript reviews significant drug interactions of azoles with other medications, as well as with food. The PubMed and Google Scholar bases were searched to collect the literature data. The interactions with anticonvulsants, antibiotics, statins, kinase inhibitors, proton pump inhibitors, non-nucleoside reverse transcriptase inhibitors, opioid analgesics, benzodiazepines, cardiac glycosides, nonsteroidal anti-inflammatory drugs, immunosuppressants, antipsychotics, corticosteroids, biguanides, and anticoagulants are presented. We also paid attention to possible interactions with drugs during experimental therapies for the treatment of COVID-19.

Successful long-term therapy of mucormycosis with isavuconazole

We present a case of a 55-year-old poorly controlled diabetic who presented to the hospital with facial pain, ophthalmoplegia, vision changes, and diabetic ketoacidosis and was diagnosed with rhinocerebral mucormycosis due to Rhizopus microsporus. He was started on liposomal amphotericin B and micafungin and went for nasal endoscopy and debridement, but the infection had progressed through the base of the skull and he received the maximum tolerated debridement. Posaconazole was added and discontinued due to elevated liver chemistry tests and was replaced with oral isavuconazole. After 6 weeks of therapy with liposomal amphotericin B and isavuconazole, he was switched to oral isavuconazole monotherapy. He underwent 30 sessions of hyperbaric oxygen therapy. Imaging showed improvement with subsequent biopsies that were negative for mucormycosis. At 13 months of therapy, his monotherapy was discontinued. He continues to have long-term sequelae including left facial droop and inability to close his left eye.

Antifungal agents and the kidney: pharmacokinetics, clinical nephrotoxicity, and interactions

INTRODUCTION

Invasive fungal infections continue to be important causes of morbidity and mortality in severely ill and immunocompromised patient populations. The past three decades have seen a considerable expansion in antifungal drug research, resulting in the clinical development of different classes of antifungal agents with different pharmacologic properties. Among drug-specific characteristics of antifungal agents, renal disposition and nephrotoxicity are important clinical considerations as many patients requiring antifungal therapy have compromised organ functions or are receiving other potentially nephrotoxic medications.

AREAS COVERED

The present article reviews incidence, severity and mechanisms of nephrotoxicity associated with antifungal agents used for prevention and treatment of invasive fungal diseases by discussing distribution, metabolism, elimination and drug-related adverse events in the context of safety data from phase II and III clinical studies.

EXPERT OPINION

Based on the available data amphotericin B deoxycholate has the highest relative potential for nephrotoxicity, followed by the lipid formulations of amphotericin B, and, to a much lesser extent and by indirect mechanisms, the antifungal triazoles.

A Canker Barking at the Wrong Knee: Thyronectria austroamericana Septic Arthritis

The mold Thyronectria austroamericana is a plant pathogen that causes canker in honey locust trees. We describe the first case of this mold causing septic arthritis in humans.

Pharmacokinetics and Bioequivalence of Isavuconazole Administered as Isavuconazonium Sulfate Intravenous Solution via Nasogastric Tube or Orally in Healthy Subjects

For critically ill patients with invasive fungal infections, a nasogastric (NG) tube can be an alternative route for administration of isavuconazonium sulfate (ISAVUSULF). This was a randomized, open-label, 2-period, 2-sequence single-dose crossover study comparing single doses of 372 mg ISAVUSULF intravenous (i.v.) solution via NG tube (test formulation) to 372-mg ISAVUSULF capsules for oral administration (reference formulation) in healthy male and female subjects. A single dose of ISAVUSULF was administered under fasting conditions on day 1 of each period, with a washout of 30 days between periods. Pharmacokinetic (PK) samples were collected predose through day 21. Standard safety and tolerability assessments were conducted in each period. The analysis of variance estimate of the study population demonstrates that the isavuconazole i.v. NG tube administration geometric least-squares (LS) mean values of the observed maximum concentration (C_max), area under the plasma concentration-time curve (AUC) to the last measurable concentration (AUC_last), AUC to time infinity (AUC_inf), and AUC from start of dosing to 72 h (AUC₇₂) were 105.3%, 97.6%, 99.3%, and 97.8%, respectively, of the corresponding oral-administration values. The geometric LS mean ratio and 90% confidence intervals for the PK parameters were completely contained within the prespecified limits of 80% to 125%. There were no deaths or serious adverse events that led to the withdrawal of treatment during the study. The study met its primary endpoint of bioequivalence between the two routes of administration. Both routes of administration were well tolerated.

Invasive aspergillosis in solid organ transplantation: Diagnostic challenges and differences in outcome in a Spanish national cohort (Diaspersot study)

BACKGROUND

The diagnosis of invasive aspergillosis (IA) can be problematic in solid organ transplantation (SOT). The prognosis greatly varies according to the type of transplant, and the impact of prophylaxis is not well defined.

PATIENTS AND METHODS

The Diaspersot cohort analyses the impact of IA in SOT in Spain during the last 10 years. Proven and probable/putative IA was included.

RESULTS

We analysed 126 cases of IA. The incidences of IA were as follows: 6.5%, 2.9%, 1.8% and 0.6% for lung, heart, liver and kidney transplantation, respectively. EORTC/MSG criteria confirmed only 49.7% of episodes. Tree-in-bud sign or ground-glass infiltrates were present in 56.3% of patients, while serum galactomannan (optical density index >0.5) was positive in 50.6%. A total of 41.3% received combined antifungal therapy. Overall mortality at 3 months was significantly lower (p < 0.001) in lung transplant recipients (14.8%) than in all other transplants [globally: 48.6%; kidney 52.0%, liver 58.3%, heart 31.2%, and combined 42.9%]. Fifty-four percent of episodes occurred despite the receipt of antifungal prophylaxis, and in 10%, IA occurred during prophylaxis (breakthrough infection), with both nebulised amphotericin (in lung transplant recipients) and candins (in the rest).

CONCLUSIONS

Invasive aspergillosis diagnostic criteria, applied to SOT patients, may differ from those established for haematological patients. IA in lung transplants has a higher incidence, but is associated with a better prognosis than other transplants. Combination therapy is frequently used for IA in SOT. Prophylactic measures require optimisation of its use within this population.

Successful treatment of Rhizopus arrhizus rhino-orbital-cerebral mucormycosis with isavuconazole salvage therapy following extensive debridement

A 61-year old lady with poorly-controlled type 2 diabetes mellitus was diagnosed with rhino-orbital-cerebral mucormycosis following presentation with sinusitis, ophthalmoplegia, proptosis and facial numbness. She was treated successfully with aggressive surgical intervention including orbital exenteration, accompanied by anti-fungal therapy with liposomal amphotericin B and posaconazole, followed by isavuconazole as salvage therapy. We discuss the challenges around optimising antifungal therapy of this lethal infection in the context of hepatic and renal toxicity.

Dissection of the Activity of Agricultural Fungicides against Clinical Aspergillus Isolates with and without Environmentally and Medically Induced Azole Resistance

Azole resistance is an emerging problem in patients with aspergillosis. The role of fungicides for resistance development and occurrence is not fully elucidated. EUCAST reference MICs of 17 fungicides (11 azoles and 6 others), five azole fungicide metabolites and four medical triazoles were examined against two reference and 28 clinical isolates of A. fumigatus, A. flavus and A. terreus with (n = 12) and without (n = 16) resistance mutations. Eight/11 azole fungicides were active against wild-type A. fumigatus, A. flavus and A. terreus, including four (metconazole, prothioconazole-desthio, prochloraz and imazalil) with low MIC₅₀ (≤2 mg/L) against all three species and epoxiconazole, propiconazole, tebuconazole and difenoconazole also against wild-type A. terreus. Mefentrifluconazole, azole metabolites and non-azole fungicides MICs were >16 mg/L against A. fumigatus although partial growth inhibition was found with mefentrifluconazole. Moreover, mefentrifluconazole and axozystrobin were active against wild-type A. terreus. Increased MICs (≥3 dilutions) were found for TR₃₄/L98H, TR₃₄⁽³⁾/L98H, TR₄₆/Y121F/T289A and G432S compared to wild-type A. fumigatus for epoxiconazole, propiconazole, tebuconazole, difenoconazole, prochloraz, imazalil and metconazole (except G432S), and for prothioconazole-desthio against TR₄₆/Y121F/T289A, specifically. Increased MICs were found in A. fumigatus harbouring G54R, M220K and M220R alterations for five, one and one azole fungicides, respectively, compared to MICs against wild-type A. fumigatus. Similarly, increased MICs wer found for A. terreus with G51A, M217I and Y491H alterations for five, six and two azole fungicides, respectively. Azole fungicides showed activity against wild-type A. fumigatus, A. terreus and A. flavus, but not against all mutant isolates, suggesting the environmental route of azole resistance may have a role for all three species.

Isavuconazole: Mechanism of Action, Clinical Efficacy, and Resistance

Increasing incidence of invasive fungal infections combined with a growing population of immunocompromised hosts has created a rising need for antifungal agents. Isavuconazole, a second-generation broad-spectrum triazole with activity against yeasts, dimorphic fungi, and molds, has a favorable safety profile and predictable pharmacokinetics. Patients typically tolerate isavuconazole well with fewer drug-drug interactions. Clinical trials have found it to be noninferior to voriconazole for invasive aspergillosis, an alternative therapy for salvage treatment of mucormycosis, and suitable for stepdown therapy with invasive candidiasis. Cross-resistance with other triazoles is common. More studies are needed to determine the role of isavuconazole in anti-mold prophylaxis in high-risk patients.

In Vitro Activities of Ravuconazole and Isavuconazole against Dematiaceous Fungi

The in vitro activities of 11 antifungals against 84 dematiaceous fungi were tested. For most tested fungal species, the MIC values of ravuconazole and isavuconazole were lower than those obtained with itraconazole, voriconazole, and posaconazole. Ravuconazole and isavuconazole appear to be more efficient against most dematiaceous fungal infections than the other triazoles. However, some pigmented fungi, such as Bipolaris spicifera and Veronaea botryosa, remain more susceptible to other triazoles or to echinocandins.

A Collaborative Tale of Diagnosing and Treating Chronic Pulmonary Aspergillosis, from the Perspectives of Clinical Microbiologists, Surgical Pathologists, and Infectious Disease Clinicians

Chronic pulmonary aspergillosis (CPA) refers to a spectrum of Aspergillus-mediated disease that is associated with high morbidity and mortality, with its true prevalence vastly underestimated. The diagnosis of CPA includes characteristic radiographical findings in conjunction with persistent and systemic symptoms present for at least three months, and evidence of Aspergillus infection. Traditionally, Aspergillus infection has been confirmed through histopathology and microbiological studies, including fungal culture and serology, but these methodologies have limitations that are discussed in this review. The treatment of CPA requires an individualized approach and consideration of both medical and surgical options. Most Aspergillus species are considered susceptible to mold-active triazoles, echinocandins, and amphotericin B; however, antifungal resistance is emerging and well documented, demonstrating the need for novel therapies and antifungal susceptibility testing that correlates with clinical response. Here, we describe the clinical presentation, diagnosis, and treatment of CPA, with an emphasis on the strengths and pitfalls of diagnostic and treatment approaches, as well as future directions, including whole genome sequencing and metagenomic sequencing. The advancement of molecular technology enables rapid and precise species level identification, and the determination of molecular mechanisms of resistance, bridging the clinical infectious disease, anatomical pathology, microbiology, and molecular biology disciplines.

Candidiasis and Mechanisms of Antifungal Resistance

Candidiasis can be present as a cutaneous, mucosal or deep-seated organ infection, which is caused by more than 20 types of Candida sp., with C. albicans being the most common. These are pathogenic yeast and are usually present in the normal microbiome. High-risk individuals are patients of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS), organ transplant, and diabetes. During infection, pathogens can adhere to complement receptors and various extracellular matrix proteins in the oral and vaginal cavity. Oral and vaginal Candidiasis results from the overgrowth of Candida sp. in the hosts, causing penetration of the oral and vaginal tissues. Symptoms include white patches in the mouth, tongue, throat, and itchiness or burning of genitalia. Diagnosis involves visual examination, microscopic analysis, or culturing. These infections are treated with a variety of antifungals that target different biosynthetic pathways of the pathogen. For example, echinochandins target cell wall biosynthesis, while allylamines, azoles, and morpholines target ergosterol biosynthesis, and 5-Flucytosine (5FC) targets nucleic acid biosynthesis. Azoles are commonly used in therapeutics, however, because of its fungistatic nature, Candida sp. evolve azole resistance. Besides azoles, Candida sp. also acquire resistance to polyenes, echinochandins, and 5FC. This review discusses, in detail, the drug resistance mechanisms adapted by Candida sp.

Review of methods and antimicrobial agents for susceptibility testing against Pythium insidiosum

Pythiosis is a life-threatening infectious disease of humans and animals caused by the oomycete microorganism Pythium insidiosum. The disease has been increasingly diagnosed worldwide. P. insidiosum inhabits freshwater and presents in two forms: mycelium and zoospore. Clinical manifestations of pythiosis include an infection of the artery, eye, skin, or gastrointestinal tract. The management of pythiosis is problematic due to the lack of effective treatment. Many patients die from an uncontrolled infection. The drug susceptibility testing provides clinically-useful information that could lead to proper drug selection against P. insidiosum. Currently, no standard CLSI protocol for the drug susceptibility of P. insidiosum is available. This review aims at describing methods and antimicrobial agents for susceptibility testing against P. insidiosum. Several in-house in vitro susceptibility methods (i.e., broth microdilution method, radial growth method, and agar diffusion method) have been established for P. insidiosum. Either mycelium or zoospore can be an inoculum. Rabbit is the commonly-used model of pythiosis for in vivo drug susceptibility testing. Based on the susceptibility results (i.e., minimal inhibitory concentration and inhibition zone), several antibacterial and antifungal drugs, alone or combination, exhibited an in vitro or in vivo effect against P. insidiosum. Some distinct compounds, antiseptic agents, essential oils, and plant extracts, also show anti-P. insidiosum activities. Successfully medical treatment, guided by the drug susceptibility data, has been reported in some pythiosis patients. Future studies should emphasize finding a novel and effective anti-P. insidiosum drug, standardizing in vitro susceptibility method and correlating drug susceptibility data and clinical outcome of pythiosis patients for a better interpretation of the susceptibility results.

Multilocus sequence typing of azole-resistant Candida auris strains, South Africa

Background

Candida auris is an emerging multidrug-resistant fungal pathogen associated with high mortality.

Methods

We investigated the genetic relatedness of clinical C. auris isolates from patients admitted to either public- or private-sector hospitals, which were submitted to a reference laboratory from 2012 to 2015. Patient demographics and clinical details were recorded. We performed antifungal susceptibility testing, sequencing of the hotspot 1 and 2 regions of the FKS1 and FKS2 genes for all isolates with an echinocandin minimum inhibitory concentration (MIC) of ≥1 µg/mL and cluster analysis using multilocus sequence typing.

Results

Eighty-five isolates were confirmed as C. auris. The median patient age was 59 years [inter-quartile range (IQR): 48–68 years], with male patients accounting for 68% of cases. Specimen types included urine (29%), blood (27%), central venous catheter tips (25%), irrigation fluid (7%), tissue (5%), respiratory tract specimens (4%) and other (3%). Ninety-seven per cent of isolates were resistant to fluconazole, 7% were resistant to both fluconazole and voriconazole, 8% were resistant to both fluconazole and echinocandins (considered multidrug resistant) and all were susceptible to amphotericin B. Of the 15 randomly selected fluconazole-resistant isolates, 14 isolates had an isavuconazole MIC ≤ 1 µg/mL. No FKS mutations were detected. Multilocus sequence typing (MLST) analysis grouped isolates into two clusters: cluster 1 and cluster 2 comprising 83 and 2 isolates, respectively.

Conclusions

Azole-resistant C. auris strains circulating in South African hospitals were related by MLST, but the possibility of nosocomial transmission should be explored using a more discriminatory technique, for example, whole genome sequencing.

A Single-Center, Open-Label Trial of Isavuconazole Prophylaxis against Invasive Fungal Infection in Patients Undergoing Allogeneic Hematopoietic Cell Transplantation

Isavuconazole is a broad-spectrum triazole approved for treatment of invasive fungal infections (IFIs). In this open-label, single-arm study, we evaluated isavuconazole for antifungal prophylaxis after allogeneic hematopoietic cell transplantation (HCT). Adult patients admitted for first HCT received micafungin 150 mg i.v. daily from admission through day +7 (D+7) post-transplantation (±2 days) followed by isavuconazole prophylaxis (i.v./p.o. 372 mg every 8 hours for 6 doses and then 372 mg daily) through maximum D+98 post-HCT. Patients were followed through D+182. The primary endpoint was prophylaxis failure, defined as discontinuation of prophylaxis for proven/probable IFI; systemic antifungal therapy for >14 days for suspected IFI; toxicity leading to discontinuation; or an adverse event. Between June 2017 and October 2018, 99 patients were enrolled in the study, of whom 95 were included in our analysis. The median patient age was 57 years (interquartile range [IQR], 50 to 66 years). Sixty-four (67%) patients received peripheral blood, 17(18%) received bone marrow, and 14 (15%) received a cord blood allograft for acute leukemia (55%), lymphoma (17%), myelodysplastic syndrome (16%), or another hematologic disease (14%). One-third (n = 31; 33%) of patients underwent CD34⁺-selected HCT. Isavuconazole prophylaxis was given for a median of 90 days (IQR, 87 to 91 days). Ten patients (10.7%) met the primary endpoint. Candidemia occurred in 3 patients (3.1%), 1 of whom had grade III skin acute graft-versus-host disease (GVHD). Toxicity leading to discontinuation occurred in 7 patients (7.4%). The most common toxicity was liver function abnormalities in 5 patients, including grade 1 transaminitis in 2 patients and grade 3 hyperbilirubinemia in 3 patients. Four patients (4.2%) had early discontinuation of isavuconazole for reasons not meeting the primary study endpoint. Six patients died during the study period, including 3 during prophylaxis and 3 during follow-up. No deaths were attributed to isavuconazole. The majority (85%) of allogeneic HCT recipients completed isavuconazole prophylaxis according to protocol. The rate of breakthrough candidemia was 3.1%, and there were no invasive mold infections. Our data support the utility of isavuconazole for antifungal prophylaxis after HCT.

Isavuconazole in Hematological Patients: Results of a Real-Life Multicentre Observational Seifem Study

Invasive fungal diseases (IFDs) remain a major clinical issue in patients with hematological malignancies (HMs). To confirm the efficacy and safety of the new azole isavuconazole (ISV) in a clinical care setting, we planned a multicenter retrospective study; we collected data on all possible/probable/proven IFDs in patients with HMs treated with ISV in 17 centers. Between July 2016 and November 2018, 128 patients were enrolled, and 122 were fully evaluable. ISV was employed as the 1st line therapy in 43 (35%) patients and as a subsequent therapy in 79 (65%) patients. The response rate was 82/122 patients (67.2%); it was similar when using ISV as a 1st or 2nd line treatment (60.5% vs 70.9%, respectively; p = 0.24). In multivariate analysis, both female sex (OR: 2.992; CI: 1.22-7.34) and induction phase of treatment (OR: 3.953; CI: 1.085-14.403) were predictive of a favorable response. At a median follow-up of 5 months, 43 (35.2%) patients were dead; the 1-year overall survival (OS) was 49.9%. In multivariate analysis, the response to ISV (OR: 0.103; CI: 0.041-0.262) and IFD refractoriness to previous antifungals (OR: 3.413; CI: 1.318-8.838) were statistically significant for OS. Adverse events (AEs) were reported in 15/122 patients (12.3%); grade 3-4 AEs were reported in 5 (4%) and led to ISV discontinuation. Our study confirms the safety and tolerability of ISV, also in diseases other than acute leukemia. Phase of hematological disease, gender and refractoriness to previous antifungals are the main predictive factors for the aforementioned response and outcome.

Invasive fungal wound infection in an otherwise healthy trauma patient (Mucor Trauma)

Background

Mucor fungi are found ubiquitously in the environment and rarely cause infections in humans. Mucormycosis is typically seen in immunocompromised patients, but has been increasingly documented in previously healthy trauma patients. Mortality due to these infections can be high due to delayed diagnosis from a subtle clinical presentation and spread of infection by angioinvasion. Early recognition and prompt treatment is critical for survival. We describe a case of invasive mucormycosis in a previously healthy trauma patient treated at a Level 1 trauma center.

Case report

A 22-year-old male presented to the hospital after being involved in a motor vehicle accident. He sustained multiple traumatic injuries and developed multi-system organ failure within 48 hours of admission. He developed invasive, soft tissue mucormycosis (Rhizopus sp) at the laparotomy site, requiring multiple surgical debridements and prompt antifungal therapy. The fungus was also cultured from respiratory secretions and likely associated with his abdominal infection. We suspect the patient was predisposed to an invasive fungal infection in the setting of multi-system organ failure and multiple blood transfusions. The patient ultimately did well and continued to improve on follow up in the outpatient setting.

Conclusions

Mucormycosis is a rare infection that has been increasingly documented in trauma patients. Early recognition together with prompt debridement and antifungal therapy is key to successful management. Understanding risk factors for post-traumatic mucormycosis should raise our index of suspicion and prompt early diagnosis and initiation of treatment. Aggressive debridement is a critical component of appropriate management due to the angioinvasive spread of the mucor fungi. This means frequent debridement beyond the demarcation of gangrenous tissue. The management of our patient demonstrates the importance of early recognition of the clinical presentation, prompt initiation of antifungal therapy, and aggressive debridement of the wound.

Considerations for Medications Commonly Utilized in the Oncology Population in the Intensive Care Unit

An increasing number of oncologic patients are presenting to the intensive care unit with complications from both their chronic disease states and cancer therapies due to improved survival rates. The management of these patients is complex due to immunosuppression (from the malignancy and/or treatment), metabolic complications, and diverse medication regimens with the potential for significant drug-drug interactions and overlapping adverse effects. This chapter will provide clinicians with an overview of non-chemotherapy medications frequently encountered in the critically ill oncologic patient, with a focus on practical considerations.

Successful eradication of chronic symptomatic Candida krusei urinary tract infection with increased dose micafungin in a liver and kidney transplant recipient: Case report and review of the literature

Treatment of symptomatic candiduria is notoriously challenging because of the limited repository of antifungals that achieve adequate urinary concentrations. Fluconazole, amphotericin B-based products, and flucytosine are established treatment options for most Candida species. Candida krusei exhibits intrinsic resistance to fluconazole and decreased susceptibility to amphotericin B and flucytosine. In transplant patients, both amphotericin B-based products and flucytosine are less desirable because of their toxicities. Other triazole antifungals are unappealing because they do not achieve adequate urinary concentrations, have multiple toxicities, and interact with transplant-related immunosuppressive medications. Echinocandins are well-tolerated but have been traditionally deferred in the treatment of symptomatic funguria because of their poor urinary concentrations but there is a small but emerging body of literature supporting their use. Here, we present a case of successful eradication of chronic symptomatic C krusei urinary tract infection with micafungin 150 milligrams daily in a liver and kidney transplant recipient, and we review the literature on treatment of symptomatic candiduria.

Drugs in Clinical Development for Fungal Infections

Despite increasing rates of invasive fungal infections being reported globally, only a single antifungal drug has been approved during the last decade. Resistance, toxicity, drug interactions and restricted routes of administration remain unresolved issues. This review focuses on new antifungal compounds which are currently in various clinical phases of development. We discuss two azoles with a tetrazole moiety that allows selective activity against the fungal CYP: VT-1161 for Candida infections and VT-1129 for cryptococcal meningoencephalitis. We also discuss two glucan synthesis inhibitors: CD101, an echinocandin with an increased half-life, and SCY-078 with oral bioavailability and increased activity against echinocandin-resistant isolates. Among the polyenes, we discuss MAT023, an encochleated amphotericin B formulation that allows oral administration. Two novel classes of antifungal drugs are also described: glycosylphosphatidylinositol inhibitors, and the leading drug APX001, which disrupt the integrity of the fungal wall; and the orotomides, inhibitors of pyrimidine synthesis with the leading drug F901318. Finally, a chitin synthesis inhibitor and progress on human monoclonal antifungal antibodies are discussed.

Pre-Existing Liver Disease and Toxicity of Antifungals

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

Successful treatment of invasive mucormycosis with isavuconazole in pediatric patients

BACKGROUND

Invasive mold infections (IMIs) are a leading cause of mortality among immunocompromised patients. Isavuconazole is a new drug that shows promise in the adult population for the treatment of IMIs. No data regarding the use of isavuconazole in pediatric patients have been published.

METHODS

Patients with a diagnosis of IMI from our pediatric hemato-oncology division, treated with isavuconazole between 2010 and 2016, were identified using the hospital's computerized database. Data including demographics, clinical course, and outcome were collected. Pharmacokinetic samples were obtained from two younger patients to guide dosing.

RESULTS

In total, three patients (4.5, 5, and 19 years of age) with invasive mucormycosis who were treated with isavuconazole were identified. All patients were treated with isavuconazole as a second line therapy and experienced improvement following the initiation of this treatment.

CONCLUSIONS

Based on our limited clinical experience, isavuconazole may be a safe and effective treatment option for children and adolescents afflicted by IMI. Prospective clinical trials should be performed in order to evaluate the pharmakokinetics and safety of isavuconazole in the pediatric population.

In Vitro Activity of Isavuconazole against Opportunistic Fungal Pathogens from Two Mycology Reference Laboratories

Monitoring antifungal susceptibility patterns for new and established antifungal agents seems prudent given the increasing prevalence of uncommon species associated with higher antifungal resistance. We evaluated the activity of isavuconazole against 4,856 invasive yeasts and molds collected worldwide. The 4,856 clinical fungal isolates, including 2,351 Candida species isolates, 97 non-Candida yeasts, 1,972 Aspergillus species isolates, and 361 non-Aspergillus molds, including 292 Mucorales isolates collected in 2015 to 2016, were tested using CLSI methods. The MIC values for isavuconazole versus Aspergillus ranged from 0.06 to ≥16 μg/ml. The modal MIC for isavuconazole was 0.5 μg/ml (range, 0.25 [A. nidulans and A. terreus species complex] to 4 μg/ml [A. calidoustus and A. tubingensis]). Eight A. fumigatus isolates had elevated isavuconazole MIC values at ≥8 μg/ml (non-wild type). Isavuconazole showed comparable activity to itraconazole against the Mucorales The lowest modal isavuconazole MIC values were seen for Rhizopus spp., R. arrhizus var. arrhizus, and R. microsporus (all 1 μg/ml). Candida species isolates were inhibited by ≤0.25 μg/ml of isavuconazole (range, 96.1% [C. lusitaniae] to 100.0% [C. albicans, C. dubliniensis, C. kefyr, and C. orthopsilosis]). MIC values were ≤1 μg/ml for 95.5% of C. glabrata isolates and 100.0% of C. krusei isolates. Isavuconazole was active against the non-Candida yeasts, including Cryptococcus neoformans (100.0% at ≤0.5 μg/ml). Isavuconazole exhibited excellent activity against most species of Candida and Aspergillus Isavuconazole was comparable to posaconazole and voriconazole against the less common yeasts and molds. Isavuconazole was generally less active than posaconazole and more active than voriconazole against the 292 Mucorales isolates. We confirm the potentially useful activity of isavuconazole against species of Rhizopus as determined by CLSI methods.

Crystal Structure of the New Investigational Drug Candidate VT-1598 in Complex with Aspergillus fumigatus Sterol 14α-Demethylase Provides Insights into Its Broad-Spectrum Antifungal Activity

Within the past few decades, the incidence and complexity of human fungal infections have increased, and therefore, the need for safer and more efficient, broad-spectrum antifungal agents is high. In the study described here, we characterized the new tetrazole-based drug candidate VT-1598 as an inhibitor of sterol 14α-demethylase (CYP51B) from the filamentous fungus Aspergillus fumigatus VT-1598 displayed a high affinity of binding to the enzyme in solution (dissociation constant, 13 ± 1 nM) and in the reconstituted enzymatic reaction was revealed to have an inhibitory potency stronger than the potencies of all other simultaneously tested antifungal drugs, including fluconazole, voriconazole, ketoconazole, and posaconazole. The X-ray structure of the VT-1598/A. fumigatus CYP51 complex was determined and depicts the distinctive binding mode of the inhibitor in the enzyme active site, suggesting the molecular basis of the improved drug potency and broad-spectrum antifungal activity. These data show the formation of an optimized hydrogen bond between the phenoxymethyl oxygen of VT-1598 and the imidazole ring nitrogen of His374, the CYP51 residue that is highly conserved across fungal pathogens and fungus specific. Comparative structural analysis of A. fumigatus CYP51/voriconazole and Candida albicans CYP51/VT-1161 complexes supports the role of H bonding in fungal CYP51/inhibitor complexes and emphasizes the importance of an optimal distance between this interaction and the inhibitor-heme iron interaction. Cellular experiments using two A. fumigatus strains (strains 32820 and 1022) displayed a direct correlation between the effects of the drugs on CYP51B activity and fungal growth inhibition, indicating the noteworthy anti-A. fumigatus potency of VT-1598 and confirming its promise as a broad-spectrum antifungal agent.

Drug development challenges and strategies to address emerging and resistant fungal pathogens

INTRODUCTION

Invasive fungal infections represent an expanding threat to public health. The recent emergence of Candida auris, which is often resistant to existing antifungal agents and is associated with a high mortality rate, underscores the urgent need for novel drug development strategies. Areas covered: In this paper, we examine both challenges and opportunities associated with antifungal drug development and explore potential avenues to accelerate the development pipeline, including data sharing, surrogate endpoints, and the role of historical controls in clinical trials. Expert commentary: We review important lessons learned from the study of other rare diseases, including mitochondrial storage diseases and certain forms of cancer that may inform strategies to develop new antifungal agents while highlighting promising new compounds such as SCY-078 for the treatment of invasive fungal infections.

Combination therapy for the treatment of pulmonary mold infections

INTRODUCTION

Pulmonary mold infections are caused by ubiquitous organisms found in soil, water, and decaying vegetation, including Aspergillus spp., the Mucormycetes, hyaline molds, and dematiaceous (black) molds. Areas covered: These infections are often a challenge to diagnose and even more difficult to treat. Recently, antifungal combination therapy has emerged as a promising strategy to treat some forms of invasive mycoses, including pulmonary mold infections. Historically, this approach has been limited due to non-uniform interpretation criteria, variations in pharmacodynamic/pharmacokinetic properties of antifungals used in combination, and an inability to predict clinical success based on in vitro data and animal models. However, recent advances have helped mitigate some of these challenges. Expert commentary: In this paper, we explore what is known about the antifungal combination therapy in the treatment of pulmonary mold infections and explore how it may impact clinical practice. We pay particular attention to novel combinations and the challenges associated with the development of new antifungal agents.

Structural analyses of Candida albicans sterol 14α-demethylase complexed with azole drugs address the molecular basis of azole-mediated inhibition of fungal sterol biosynthesis

With some advances in modern medicine (such as cancer chemotherapy, broad exposure to antibiotics, and immunosuppression), the incidence of opportunistic fungal pathogens such as Candida albicans has increased. Cases of drug resistance among these pathogens have become more frequent, requiring the development of new drugs and a better understanding of the targeted enzymes. Sterol 14α-demethylase (CYP51) is a cytochrome P450 enzyme required for biosynthesis of sterols in eukaryotic cells and is the major target of clinical drugs for managing fungal pathogens, but some of the CYP51 key features important for rational drug design have remained obscure. We report the catalytic properties, ligand-binding profiles, and inhibition of enzymatic activity of C. albicans CYP51 by clinical antifungal drugs that are used systemically (fluconazole, voriconazole, ketoconazole, itraconazole, and posaconazole) and topically (miconazole and clotrimazole) and by a tetrazole-based drug candidate, VT-1161 (oteseconazole: (R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(1H-tetrazol-1-yl)-1-(5-(4-(2,2,2-trifluoroethoxy)phenyl)pyridin-2-yl)propan-2-ol). Among the compounds tested, the first-line drug fluconazole was the weakest inhibitor, whereas posaconazole and VT-1161 were the strongest CYP51 inhibitors. We determined the X-ray structures of C. albicans CYP51 complexes with posaconazole and VT-1161, providing a molecular mechanism for the potencies of these drugs, including the activity of VT-1161 against Candida krusei and Candida glabrata, pathogens that are intrinsically resistant to fluconazole. Our comparative structural analysis outlines phylum-specific CYP51 features that could direct future rational development of more efficient broad-spectrum antifungals.

Diagnosis, classification, and therapeutic interventions for sinopulmonary Aspergillosis

INTRODUCTION

Sinopulmonary aspergillosis represents a diverse collection of allergic, invasive, and chronic sinus and respiratory conditions. These diseases can affect patients with and without immune impairment and in some cases may be life-threatening. Areas covered: We review the diagnosis, classification, and therapeutic options available to treat sinopulmonary aspergillosis and look ahead to emerging diagnostic and therapeutic options that may soon play an important role in clinical practice. Expert commentary: Histopathology and tissue culture remain the gold standard for the diagnosis of invasive sinopulmonary aspergillosis, but several new molecular detection methods have recently emerged, including various PCR-based platforms, MALDI-TOF, and lateral flow assays. We examine these methodologies as well as the barriers associated with the standardization, validation, and implementation. We also explore the pipeline of antifungal agents in development to treat sinopulmonary aspergillosis.