Caspofungin for the treatment of fungal infections: a systematic review of randomized controlled trials

Exploring the frontiers of therapeutic breadth of antifungal peptides: A new avenue in antifungal drugs

The growing prevalence of fungal infections alongside rising resistance to antifungal drugs poses a significant challenge to public health safety. At the close of the 2000s, major pharmaceutical firms began to scale back on antimicrobial research due to repeated setbacks and diminished economic gains, leaving only smaller companies and research labs to pursue new antifungal solutions. Among various natural sources explored for novel antifungal compounds, antifungal peptides (AFPs) emerge as particularly promising. Despite their potential, AFPs receive less focus than their antibacterial counterparts. These peptides have been sourced extensively from nature, including plants, animals, insects, and especially bacteria and fungi. Furthermore, with advancements in recombinant biotechnology and computational biology, AFPs can also be synthesized in lab settings, facilitating peptide production. AFPs are noted for their wide-ranging efficacy, in vitro and in vivo safety, and ability to combat biofilms. They are distinguished by their high specificity, minimal toxicity to cells, and reduced likelihood of resistance development. This review aims to comprehensively cover AFPs, including their sources-both natural and synthetic-their antifungal and biofilm-fighting capabilities in laboratory and real-world settings, their action mechanisms, and the current status of AFP research.

ONE-SENTENCE SUMMARY

This comprehensive review of AFPs will be helpful for further research in antifungal research.

Meta-analysis of the safety of voriconazole in definitive, empirical, and prophylactic therapies for invasive fungal infections

Background

Voriconazole has been used in the treatment and prophylaxis of invasive fungal infections (IFIs) while its wide use was limited by some frequent adverse events, especially neurotoxicity, hepatotoxicity and even renal disruption. The aim of this study was to comprehensively compare voriconazole-induced toxicity, including tolerability, neurotoxicity, visual toxicity, hepatotoxicity and nephrotoxicity with the composite of other antifungals commonly used in clinic.

Methods

Bibliography databases were searched to select randomized controlled trials providing information about the incidence of toxicity referred above. A total of 4122 patients from 16 studies were included in the meta-analysis.

Results

Analysis of individual types of toxicity showed that there was a significant difference between voriconazole and the composite of other antifungal agents. The primary outcome, the tolerability of voriconazole was slightly inferior (OR = 1.71, 95% CI = 1.21–2.40, P = 0.002) and it is noteworthy that the probabilities of neurotoxicity and visual toxicity were around twice higher and six-fold for voriconazole compared with the counterpart (OR = 1.99, 95% CI = 1.05–3.75, P = 0.03 and OR = 6.50, 95% CI = 2.93–14.41, P < 0.00001, respectively). Hepatotoxicity was more common in voriconazole group (OR = 1.60, 95% CI = 1.17–2.19, P = 0.003) whereas its pooled risk of nephrotoxicity was about half of the composite of other five antifungal agents (OR = 0.46, 95% CI = 0.26–0.84, P = 0.01).

Conclusion

Our analysis has revealed differences in multiple types of toxicity induced by VRC versus other antifungals and quantified the corresponding pooled risks, which could provide an alternative for patients with a certain antifungal intolerance and help the clinician to select the optimal intervention.

Electronic supplementary material

The online version of this article (10.1186/s12879-017-2913-8) contains supplementary material, which is available to authorized users.

Clinical hepatotoxicity associated with antifungal agents

INTRODUCTION

Invasive fungal diseases (IFDs) are a leading cause of morbidity and mortality among immunocompromised patients with bone marrow failure syndromes, hematological malignancies, hematopoietic stem cell transplantation (HSCT), those admitted in intensive care units (ICUs) and those with prolonged febrile neutropenia. IFDs occur in a setting of multiple morbidities and are associated with case fatality rates between 30 and 70%. Along with the development of classes and compounds, the last two decades have seen substantial improvements in the prevention and management of these infections and an overall increased use of antifungal agents. Areas covered: All antifungal agents, including amphotericin B formulations, echinocandins and the triazoles, may cause hepatic toxicity that ranges from mild and asymptomatic abnormalities in liver function tests to substantial liver injury and fulminant hepatic failure. Expert opinion: The present article reviews incidence and severity of hepatotoxicity associated with different classes and agents to provide a better understanding of this specific end organ toxicity and safer use of antifungal agents A thorough understanding of the distribution, metabolism, elimination and drug-drug interactions of antifungal agents used for management of IFDs in combination with safety data from clinical trials, pharmacokinetic and pharmacodynamic studies may guide the use of antifungal treatment in patients at high risk for the development of hepatic dysfunction and in those with underlying liver damage due to cytotoxic therapy.

[The development of appropriate dosage of anti-bacterial and anti-fungal agents based on pharmacokinetics and pharmacodynamics]

An initial loading procedure has been recommended to enable teicoplanin to promptly reach an effective serum concentration for the treatment of methicillin-resistant Staphylococcus aureus (MRSA). The mean trough concentrations were 13.2 mg/L for patients with eradication of MRSA. I showed that the administration of ≥36 mg/kg during the first 3 days was effective in promptly obtaining a trough concentration target of ≥13 mg/L for the initial treatment of MRSA infections. The major adverse effect associated with linezolid treatment is reversible myelosuppression, primarily thrombocytopenia. I demonstrated that the incidence of linezolid-induced thrombocytopenia was higher among patients with renal failure than in patients with normal renal function. A statistically significant (p<0.01) and strong correlation (r=0.933) was observed between linezolid and creatinine clearance. A negative correlation (r=-0.567) was also shown between linezolid clearance and blood urea nitrogen. Voriconazole trough plasma concentration has been reported to correlate with hepatotoxicity. Logistic regression analysis revealed that the therapeutic range for the voriconazole trough concentration should be 2-4 mg/L. Nonlinear pharmacokinetic analysis suggested that voriconazole therapy should be initiated with a dose of 7.2-8.9 mg/kg/day for CYP2C19 wild type and 4.4-6.5 mg/kg/day for the non-wild type in patients. Anaemia and thrombocytopenia are major side effects of liposomal amphotericin B. I demonstrated that the doses of liposomal amphotericin B estimated to cause side effects of a low red blood cell count, anaemia and thrombocytopenia with 50% probability are 4.0, 3.3 and 3.0 mg/kg/day, respectively.

continuous versus conventional infusion of amphotericin B deoxycholate: a meta-analysis

Background

Treatment with Amphotericin B (AmB) deoxycholate, which is still used widely, particularly in low-resource countries, has been challenged due to nephrotoxicity. We sought to study whether continuous infusion of AmB deoxycholate reduces nephrotoxicity retaining, however, the effectiveness of the drug.

Methods

PubMed and Scopus databases were systematically searched to identify studies comparing the outcomes of patients receiving 24-h infusion of AmB (“continuous group”) and those receiving 2–6-h infusion of AmB (“conventional group”). Nephrotoxicity and all-cause mortality were the primary outcomes of the review, while treatment failure was the secondary outcome.

Results

Five studies met the inclusion criteria; one randomized controlled trial, two prospective cohort studies, and two retrospective cohort studies. The majority of patients were neutropenic with an underlying hematologic malignancy. All 5 studies (392 patients) provided data regarding the development of nephrotoxicity. A non-significant trend towards lower nephrotoxicity was observed for patients receiving continuous infusion of AmB compared with those receiving conventional infusion [RR = 0.61 (95% CI 0.36, 1.02)]. Four studies (365 patients) provided data regarding mortality; no relevant difference was detected between patients receiving continuous and those receiving conventional infusion of AmB [RR = 0.81 (95% CI 0.36, 1.83)]. Data on treatment failure of the two methods of administration was insufficient for meaningful conclusions.

Conclusion

The available evidence from mainly non-randomized studies suggests that continuous infusion of AmB deoxycholate might offer an advantage over the conventional infusion regarding the development of nephrotoxicity, without compromising patient survival. Further randomized studies are needed to investigate this issue.

Human monoclonal antibody-based therapy in the treatment of invasive candidiasis

Invasive candidiasis (IC) represents the leading fungal infection of humans causing life-threatening disease in immunosuppressed and neutropenic individuals including also the intensive care unit patients. Despite progress in recent years in drugs development for the treatment of IC, morbidity and mortality rates still remain very high. Historically, cell-mediated immunity and innate immunity are considered to be the most important lines of defense against candidiasis. Nevertheless recent evidence demonstrates that antibodies with defined specificities could act with different degrees showing protection against systemic and mucosal candidiasis. Mycograb is a human recombinant monoclonal antibody against heat shock protein 90 (Hsp90) that was revealed to have synergy when combined with fluconazole, caspofungin, and amphotericin B against a broad spectrum of Candida species. Furthermore, recent studies have established an important role for Hsp90 in mediating Candida resistance to echinocandins, giving to this antibody molecule even more attractive biological properties. In response to the failure of marketing authorization by the CHMP (Committee for Medicinal Products for Human Use) a new formulation of Mycograb, named Mycograb C28Y variant, with an amino acid substitution was developed in recent years. First data on Mycograb C28Y variant indicate that this monoclonal antibody lacked efficacy in a murine candidiasis model.

The antifungal occidiofungin triggers an apoptotic mechanism of cell death in yeast

Occidiofungin is a nonribosomally synthesized cyclic peptide having a base mass of 1200 Da. It is naturally produced by the soil bacterium Burkholderia contaminans MS14 and possesses potent broad-spectrum antifungal properties. The mechanism of action of occidiofungin is unknown. Viability, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), reactive oxygen species (ROS) detection, membrane and cell wall stability, and membrane mimetic assays were used to characterize the effect of occidiofungin on yeast cells. Confocal and electron microscopy experiments were used to visualize morphological changes within treated cells. TUNEL and ROS detection assays revealed an increase in fluorescence with increasing concentrations of the antifungal. Yeast cells appeared to shrink in size and showed the presence of 'dancing bodies' at low drug concentrations (1 μg/mL). A screen carried out on Saccharomyces cerevisiae gene deletion mutants in the apoptotic and autophagy pathways identified the apoptotic gene for YCA1, as having an important role in occidiofungin response as cells deleted for this gene exhibit a 2-fold increase in resistance. Results from our experiments demonstrate that the mechanism of action for occidiofungin in yeast is different from that of the common classes of antifungals used in the clinic, such as azoles, polyenes, and echinocandins. Our study also indicates that occidiofungin causes cell death in yeast through an apoptotic mechanism of action.

Antifungal therapy for newborn infants with invasive fungal infection

BACKGROUND

A variety of antifungal drugs, drug preparations and drug combinations are available to treat newborn infants with suspected or confirmed invasive fungal infection. There is a need to assess their relative merits.

OBJECTIVES

To assess the effect of treatment with different antifungal drugs, drug preparations or drug combinations on mortality and morbidity in newborn infants with suspected or confirmed invasive fungal infection.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group. This included searches of the Cochrane Central Register of Controlled Trials (The Cochrane Library, 2012, Issue 2), MEDLINE, EMBASE, CINAHL (to March 2012), conference proceedings and previous reviews.

SELECTION CRITERIA

Randomised and quasi-randomised control trials comparing one antifungal agent or combination of agents with another in newborn infants with suspected or confirmed invasive fungal infection.

DATA COLLECTION AND ANALYSIS

We extracted the data using the standard methods of the Cochrane Neonatal Review Group, with separate evaluation of trial quality and data extraction by each author, and synthesis of data using risk ratio and risk difference.

MAIN RESULTS

We identified only one small trial in which 24 newborn infants participated. This trial compared the use of fluconazole versus amphotericin B (plus 5-fluorocytosine if fungal meningitis present). The trial did not detect a statistically significant effect on mortality (risk ratio 0.73; 95% confidence interval 0.26 to 2.05).

AUTHORS' CONCLUSIONS

There are insufficient data to inform practice. Large randomised controlled trials are required to compare antifungal drugs, drug preparations or drug combinations for treating newborn infants with invasive fungal infection.

Safety analysis of liposomal amphotericin B in adult patients: anaemia, thrombocytopenia, nephrotoxicity, hepatotoxicity and hypokalaemia

Liposomal amphotericin B (L-AmB), which was developed to reduce side effects, has been shown to have a better safety profile than both the deoxycholate and lipid complex forms of amphotericin B; however, the frequency of major side effects is still unclear. Thus, the aim of the present study was to assess retrospectively the frequency of L-AmB-induced anaemia, thrombocytopenia, nephrotoxicity, hepatotoxicity and hypokalaemia as well as the relationship between daily dose of L-AmB and these side effects. A low red blood cell (RBC) count (post-/pre-treatment) and anaemia were observed in 7 and 10 of 21 adult patients, respectively. Thrombocytopenia was observed in 11 of 19 adult patients. Doses of L-AmB that are estimated to cause side effects of a low RBC count, anaemia and thrombocytopenia with 50% probability are 4.0, 3.3 and 3.0mg/kg/day, respectively. Nephrotoxicity was observed in 6 of 22 patients. Variations of total bilirubin, γ-glutamyl transpeptidase, aspartate aminotransferase and alanine aminotransferase used as indices of hepatotoxicity were observed in 6, 7, 8 and 8 of 22 patients, respectively. Hypokalaemia was observed in 4 of 9 patients; however, nephrotoxicity, hepatotoxicity and hypokalaemia were not caused in a dose-dependent manner. In conclusion, the present analyses showed that L-AmB dose-dependently induced anaemia and thrombocytopenia in adult patients. It is important to pay attention to causing anaemia and thrombocytopenia when patients are receiving L-AmB at doses of >3.3mg/kg/day and >3.0mg/kg/day, respectively.

Antifungal activity of amphotericin B conjugated to carbon nanotubes

Amphotericin B (AMB) has long been considered the most effective drug in the treatment of serious invasive fungal infections. There are, however, major limitations to its use, due to several adverse effects, including acute infusional reactions and, most relevant, a dose-dependent nephrotoxicity. At least some of these effects are attributed to the aggregation of AMB as a result of its poor water solubility. To overcome this problem, reformulated versions of the drug have been developed, including a micellar dispersion of AMB with sodium deoxycholate (AMBD), its encapsulation into liposomes, or its incorporation into lipidic complexes. The development of nanobiotechnologies provides novel potential drug delivery systems that make use of nanomaterials such as functionalized carbon nanotubes (f-CNTs), which are emerging as an innovative and efficient tool for the transport and cellular translocation of therapeutic molecules. In this study, we prepared two conjugates between f-CNTs and AMB. The antifungal activity of these conjugates was tested against a collection of reference and clinical fungal strains, in comparison to that of AMB alone or AMBD. Measured minimum inhibition concentration (MIC) values for f-CNT-AMB conjugates were either comparable to or better than those displayed by AMB and AMBD. Furthermore, AMBD-resistant Candida strains were found to be susceptible to f-CNT-AMB 1. Additional studies, aimed at understanding the mechanism of action of the conjugates, suggest a nonlytic mechanism, since the compounds show a major permeabilizing effect on the tested fungal strains only after extended incubation. Interestingly, the f-CNT-AMB 1 does not show any significant toxic effect on Jurkat cells at antifungal concentrations.

Susceptibility of Candida spp. clinical isolates to antimycotics and disinfectants

The incidence of candidiasis among immunocompromised patients and emergence of antimycotics resistant strains has increased significantly. The aims of this study were: to examine the in vitro activity of antimycotics and biocides against Candida clinical isolates; to detect cross-resistance of fungi to these preparations and to estimate whether disinfectants applied in hospital areas are active against clinical Candida isolates. In vitro susceptibility of 102 Candida isolates to eight antimycotics was examined by Etest and ATB Fungus. Sensitivity of these strains to four disinfectants and an antiseptic agent was tested according to EN 1275:2005. Amphotericin B, caspofungin and 5-fluorocytosine were the most effective antimycotics against all Candida isolates. Resistance to itraconazole and fluconazole was observed among C. krusei and C. glabrata. The MICs (Minimal Inhibitory Concentrations) for ketoconazole, voriconazole and posaconazole against Candida albicans ranged: 0.003 - >32 μg/ml and one strain was resistant to three agents tested. All analysed Candida strains were sensitive to biocides containing either chlorine, aldehyde, alcohol mixtures, glucoprotamin or chlorhexidine gluconate with isopropanol. Sensitivity to these agents was observed at concentrations lower than those concentrations recommended by manufacturers to achieve proper biocidal activity to those preparations. Our data suggest that these disinfectants can be effectively applied in clinical wards to prevent nosocomial Candida infections.

Systematic review and meta-analysis of the tolerability and hepatotoxicity of antifungals in empirical and definitive therapy for invasive fungal infection

To evaluate the tolerability and liver safety profiles of the systemic antifungal agents commonly used for the treatment of invasive fungal infection, we conducted a systematic review and meta-analysis of randomized controlled trials published before 31 August 2009. Two reviewers independently applied selection criteria, performed quality assessment, and extracted data. We used the beta-binomial model to account for variation across studies and the maximum likelihood method to estimate the pooled risks. We identified 39 studies with more than 8,000 enrolled patients for planned comparisons. The incidence rates of treatment discontinuation due to adverse reactions and liver injury associated with antifungal therapy ranged widely. The pooled risks of treatment discontinuation due to adverse reactions were above 10% for amphotericin B formulations and itraconazole, whereas they were 2.5% to 3.8% for fluconazole, caspofungin, and micafungin. We found that 1.5% of the patients stopped itraconazole treatment due to hepatotoxicity. Furthermore, 19.7% of voriconazole users and 17.4% of itraconazole users had elevated serum liver enzyme levels, although they did not require treatment discontinuation, whereas 2.0% or 9.3% of fluconazole and echinocandin users had elevated serum liver enzyme levels but did not require treatment discontinuation. The results were similar when we stratified the data by empirical or definitive antifungal therapy. Possible explanations for antifungal agent-related hepatotoxicity were confounded by antifungal prescription to patients with a high risk of liver injury, the increased chance of detection of hepatotoxicity due to prolonged treatment, or the pharmacological entity.

Invasive candidiasis in pediatric intensive care units

Candidemia and disseminated candidiasis are major causes of morbidity and mortality in hospitalized patients especially in the intensive care units (ICU). The incidence of invasive candidasis is on a steady rise because of increasing use of multiple antibiotics and invasive procedures carried out in the ICUs. Worldwide there is a shifting trend from C. albicans towards non albicans species, with an associated increase in mortality and antifungal resistance. In the ICU a predisposed host in one who is on broad spectrum antibiotics, parenteral nutrition, and central venous catheters. There are no pathognomonic signs or symptoms. The clinical clues are: unexplained fever or signs of severe sepsis or septic shock while on antibiotics, multiple, non-tender, nodular erythematous cutaneous lesions. The spectrum of infection with candida species range from superficial candidiasis of the skin and mucosa to more serious life threatening infections. Treatment of candidiasis involves removal of the most likely source of infection and drug therapy to speed up the clearance of infection. Amphotericin B remains the initial drug of first choice in hemodynamically unstable critically ill children in the wake of increasing resistance to azoles. Evaluation of newer antifungal agents and precise role of prophylactic therapy in ICU patients is needed.

Double-blind active-control trials: beware the comparator you keep

The indirect impact of the known comparator drug in double-blind comparative clinical trials of novel agents is underappreciated, despite its potentially pernicious effects. This hypothesis-generating analysis illustrates potential spillover effects of a comparator (amphotericin) in the evaluation of the first member (caspofungin) of a novel class (echinocandins) of antifungal drugs. Reported rates of drug-related fever in the first 3 studies of caspofungin for the treatment of mucosal candidiasis in patients with advanced human immunodeficiency virus infection were retrospectively analyzed. We compared patients who received 50 mg of caspofungin per day in a double-blind trial that used fluconazole as the comparator with patients who received the corresponding dosage in 2 similar earlier studies that used amphotericin as the comparator. With respect to the incidence of drug-related fever, the difference between the concurrent caspofungin and fluconazole groups was less than the difference between caspofungin groups from studies that used different comparators. In phase II/III blinded, active-control trials, the reporting of adverse experiences attributed to a first-in-class drug might be confounded to a variable degree by expectations regarding a well-known comparator.