A randomized, double blind, comparative trial of micafungin (FK463) vs. fluconazole for the treatment of oesophageal candidiasis

Echinocandins: The Newest Class of Antifungals

Objective:

To review the mechanism of action, antifungal spectrum of activity, pharmacodynamics, pharmacokinetics, clinical efficacy, and safety of the echinocandins.

Data Sources:

A MEDLINE search (1982–May 2009) was conducted for articles published in the English language using the key words caspofungin, micafungin, anidulafungin, and echinocandins.

Study Selection and Data Extraction:

Medicinal chemistry, in vitro, and animal studies, as well as human trials were reviewed for information on the pharmacodynamics, pharmacokinetics, efficacy, and safety of each echinocandin. Clinical trials were reviewed and included to compare and contrast the available echinocandins.

Data Synthesis:

Three echinocandin antifungal agents are currently approved for use in the US: caspofungin, micafungin, and anidulafungin. The echinocandins have a unique mechanism of action, inhibiting β-(1,3)-d-glucan synthase, an enzyme that is necessary for the synthesis of an essential component of the cell wall of several fungi. The echinocandins display fungistatic activity against Aspergillus spp. and fungicidal activity against most Candida spp., including strains that are fluconazole-resistant. The echinocandins have been shown to be efficacious for the treatment of esophageal candidiasis, candidemia, and invasive candidiasis. In addition, caspofungin has demonstrated efficacy as empiric treatment of febrile neutropenia and salvage therapy for the treatment of invasive aspergillosis, and it is the only echinocandin approved for use in pediatric patients. Micafungin is the only echinocandin approved for use as prophylaxis against Candida infections in patients undergoing hematopoietic stem cell transplantation. Overall, resistance to echinocandins is still rare, and all agents are well tolerated, with similar adverse effect profiles and few drug–drug interactions.

Conclusions:

Echinocandins, the newest addition to the arsenal of antifungals, offer potential advantages over other classes of agents. Clinicians should assess their distinguishing characteristics, including route of metabolism, drug interaction profile, and approved indications for use, when determining which agent to include on a formulary.

Pharmacotherapy of Candida Infections with Echinocandins

The classic recommended antifungal agents for the treatment of invasive Candida infections were amphotericin B, a lipid formulation of amphotericin B and fluconazole in both neutropenic or nonneutropenic patients as either primary or alternative therapies. Voriconazole has been recommended when additional coverage for filamentous fungi is needed (e.g. neutropenic patients). More recently and based on well designed comparative clinical trials, the three echinocandins, caspofungin, anidulafungin and micafungin have been added as primary or alternative therapies especially for critically ill or neutropenic patients. In general, the echinocandins are most useful when patients have previously been exposed to an azole or are unstable.

Micafungin: a sulfated echinocandin

Micafungin is the second approved antifungal agent in the echinocandin series and is now used worldwide in chemotherapy for life-threatening fungal infections. It is water-soluble and is semi-synthesized from the acylated cyclic hexapeptide FR901379, a natural product from the fungus Coleophoma empetri F-11899, through enzymatic deacylation of FR901379, followed by chemical reacylation with the optimized N-acyl side chain. The water solubility of micafungin is ascribed to a sulfate moiety in the molecule. This feature differentiates micafungin from other echinocandin members. Micafungin is a potent inhibitor of 1,3-beta-glucan synthase, an enzyme necessary for cell-wall synthesis of several fungal pathogens.

Micafungin activity against Candida albicans with diverse azole resistance phenotypes

OBJECTIVES

The purpose of this study was to investigate whether mechanisms of azole resistance in Candida albicans contribute to reduced micafungin activity in vitro.

METHODS

MICs were determined for a collection of strains with well-characterized mechanisms of azole resistance obtained from systemic, oral and vaginal infections. This collection of strains includes those with resistance-associated phenotypes. All known molecular mechanisms of azole resistance are included in this set of isolates (alone or in combination). Micafungin activity was further investigated for a subset of isolates by agar dilution.

RESULTS

There was no correlation between any of the azole resistance mechanisms or resistance phenotypes and micafungin activity as determined by MIC, even in isolates with cross-resistance to multiple azole drugs. Overexpression of the ABC transporter CDR2 has been suggested to contribute to reduced echinocandin activity in agar dilution studies. By broth microdilution, there was no difference in MIC between the pump overexpressors and the collection as a whole. However, azole-resistant isolates from matched strains exhibited a small increase in their micafungin MICs relative to their susceptible controls. By agar dilution analysis, multiple CDR2-overexpressing strains exhibited reduced growth in the presence of micafungin relative to the laboratory strain SC5314.

CONCLUSIONS

Azole resistance mechanisms do not contribute to increased micafungin MIC as determined by broth microdilution. However, within sets of matched isolates, strains overexpressing CDR2 had a slight increase in micafungin MIC. Changes in micafungin susceptibility are associated with CDR2 overexpression in agar dilution tests.

Management of fungal infections following allogeneic stem cell transplantation

Fungal infection remains an important complication in allogeneic stem cell transplantation (allo-SCT). Since the prognosis of fungal infection is poor, prophylaxis is critical for its management; owing to recent progression in allo-SCT management and widespread use of reduced-intensity regimens, the strategy of infectious prophylaxis has also changed. Various antifungals have recently been developed and applied to clinical use. A major change in antifungal management will probably occur in the next few years.

Correlation of MIC with outcome for Candida species tested against caspofungin, anidulafungin, and micafungin: analysis and proposal for interpretive MIC breakpoints

The CLSI Antifungal Subcommittee followed the M23-A2 "blueprint" to develop interpretive MIC breakpoints for anidulafungin, caspofungin, and micafungin against Candida species. MICs of < or = 2 microg/ml for all three echinocandins encompass 98.8 to 100% of all clinical isolates of Candida spp. without bisecting any species group and represent a concentration that is easily maintained throughout the dosing period. Data from phase III clinical trials demonstrate that the standard dosing regimens for each of these agents may be used to treat infections due to Candida spp. for which MICs are as high as 2 microg/ml. An MIC predictive of resistance to these agents cannot be defined based on the data from clinical trials due to the paucity of isolates for which MICs exceed 2 microg/ml. The clinical data set included only three isolates from patients treated with an echinocandin (caspofungin) for which the MICs were > 2 microg/ml (two C. parapsilosis isolates at 4 microg/ml and one C. rugosa isolate at 8 microg/ml). Based on these data, the CLSI subcommittee has decided to recommend a "susceptible only" breakpoint MIC of < or = 2 microg/ml due to the lack of echinocandin resistance in the population of Candida isolates thus far. Isolates for which MICs exceed 2 microg/ml should be designated "nonsusceptible" (NS). For strains yielding results suggestive of an NS category, the organism identification and antimicrobial-susceptibility test results should be confirmed. Subsequently, the isolates should be submitted to a reference laboratory that will confirm the results by using a CLSI reference dilution method.

Micafungin for the prophylaxis and treatment of Candida infections

Invasive fungal infection is a significant cause of morbidity and mortality worldwide. The incidence of these infections is steadily increasing. In addition, strains resistant to many commonly used antifungal agents are becoming more prevalent. Many new antifungals have become commercially available in recent years, which have vastly improved the ability to treat these infections effectively. Micafungin is one of three commercially available echinocandins available for use in the USA. This class of agents possess a unique mechanism of action that helps to reduce toxicity while maintaining potent antifungal activity. Micafungin is currently approved for the treatment of esophageal candidiasis in adults and is the only in its class approved for the prophylaxis of Candida infection in patients who have undergone hematopoietic stem cell transplantation. It was also recently approved in the USA for the treatment of candidemia and other forms of invasive candiaisis (acute disseminated candiaisis, Candida peritonitis and abscess). In general, micafungin is well tolerated and has favorable safety and drug-interaction profiles.

Advances in antifungal therapy

The prevalence of invasive fungal infections (IFIs) has increased over the past three decades owing to the increasing numbers of immunocompromised hosts. These infections are associated with significant morbidity and mortality. Recent significant advances in antifungal therapy include the broad-spectrum triazoles (voriconazole and posaconazole) and a new class of antifungals, the echinocandins (caspofungin, micafungin, and anidulafungin). New treatment strategies, such as combination therapy and pre-emptive therapy, are being investigated. There have also been significant improvements in diagnostics; the galactomannan enzyme immunoassay and the beta-glucan test are now part of the EORTC/MSG criteria for diagnosis of IFI. Despite these advances, there remain a number of unanswered questions regarding optimal management of serious fungal infections, and research continues to discover and develop new therapies and evaluate new management strategies.

Early clinical experience with anidulafungin at a large tertiary care medical center

STUDY OBJECTIVE

To evaluate early clinical experience with anidulafungin.

DESIGN

Retrospective cohort study.

SETTING

Large, university-affiliated, tertiary care medical center.

PATIENTS

All patients receiving anidulafungin between July 15, 2006, and January 15, 2007.

MEASUREMENTS AND MAIN RESULTS

Thirty-five patients received at least one dose of anidulafungin. Safety and tolerability were evaluated in all patients; efficacy outcomes were assessed in 13 patients who had a documented fungal infection and received anidulafungin for a minimum of 5 days. Common conditions at baseline were hepatic dysfunction (25 patients [71%]), severe sepsis (17 patients [49%]), and solid organ or hematopoietic stem cell transplantation (10 patients [29%]). Eight patients (23%) were receiving drugs with the potential to interact with echinocandins other than anidulafungin. Seventeen (49%) of the 35 patients received anidulafungin as empiric antifungal therapy. Anidulafungin was used to treat invasive candidiasis in seven patients (20%) and candidemia in 10 patients (29%); Candida albicans or Candida glabrata was isolated most frequently in these two infections combined (7 isolates each [41%]/17 infections). A favorable efficacy outcome was noted in 10 (77%) of 13 evaluable patients. One patient developed breakthrough Candida parapsilosis fungemia while receiving anidulafungin. Overall, anidulafungin was well tolerated, with only one patient having an infusion- related reaction. Anidulafungin was also well tolerated among patients receiving concomitant metronidazole.

CONCLUSION

Anidulafungin was well tolerated and produced favorable outcomes in the majority of the patients evaluated. The availability of anidulafungin makes it a feasible option for antifungal therapy, particularly in patients who have hepatic dysfunction and in those who are receiving drugs than can interact with other echinocandins.

Oesophageal candidiasis in elderly patients: risk factors, prevention and management

This article reviews risk factors, prevention and management of oesophageal candidiasis (OC) in the elderly. Putative risk factors for OC in the elderly include old age itself, malignant disease, antibacterial and corticosteroid use, chronic obstructive pulmonary disease, acid suppression treatment, oesophageal dysmotility and other local factors, diabetes mellitus and HIV/AIDS. We have found evidence for a risk association between OC in the elderly and malignant disease (both haematological and non-haematological), antibacterial therapy and corticosteroid (including inhaled corticosteroids) use. We also found evidence of an association between OC in the elderly and oesophageal dysmotility or HIV/AIDS, but little direct evidence of an association between diabetes or old age per se. The literature on OC in the elderly is not large. The published series evaluating OC in this age group are small in size, often do not contain controls and mostly contain only limited information about the age of the patients. Prevention of OC is mainly the avoidance of exposure to the risk factors wherever possible. Specific measures such as highly active antiretroviral therapy in AIDS, prophylactic fluconazole when receiving chemotherapy for malignancy, using spacing devices, mouth rinsing soon after inhalation of corticosteroids and avoiding the use of cortiocosteroids just before bedtime are useful. OC is often responsive to a 2- to 3-week course of oral fluconazole, but resistance may be encountered in AIDS or in the presence of uncorrected anatomical factors in the oesophagus. Itraconazole solution, voriconazole or caspofungin may be used in refractory cases. Use of amphotericin B is restricted because of its narrow therapeutic index.

Current options in antifungal pharmacotherapy

Infections caused by yeasts and molds continue to be associated with high rates of morbidity and mortality in both immunocompromised and immunocompetent patients. Many antifungal drugs have been developed over the past 15 years to aid in the management of these infections. However, treatment is still not optimal, as the epidemiology of the fungal infections continues to change and the available antifungal agents have varying toxicities and drug-interaction potential. Several investigational antifungal drugs, as well as nonantifungal drugs, show promise for the management of these infections.

Micafungin sodium, the second of the echinocandin class of antifungals: theory and practice

Micafungin is a new drug in the echinocandin class and is currently being investigated in Phase III clinical trials. Like other echinocandins, it inhibits 1,3-beta-D-glucan synthesis, thus achieving fungicidal activity against virtually all Candida spp., including those resistant to fluconazole, and fungistatic activity against Aspergillus spp. Micafungin sodium is available for intravenous administration only. It has a favorable safety and drug-drug interaction profile. Micafungin has been approved by the US FDA for treatment of esophageal candidiasis and for antifungal prophylaxis during the pre-engraftment phase in patients undergoing hematopoietic stem cell transplantation. Considering the competitive pricing as well as the good tolerability and efficacy, at present micafungin seems to be another choice for both of these indications. Current research has proven micafungin sodium to add a rational and effective option to the antifungal armamentarium, especially in esophageal candidiasis refractory to fluconazole treatment, in those intolerant to triazoles or in patients needing concomitant therapy interacting with triazoles. In addition to the current indications, recent uncontrolled clinical trials have demonstrated a marked success in the treatment of candidemia and invasive candidiasis. Results from in vitro studies, animal models, small clinical trials, as well as the obvious comparison with the more established caspofungin, hint at possible future indications such as invasive aspergillosis and empirical antifungal therapy. However, preclinical data on micafungin is inconsistent and published well-designed clinical studies are scarce. More controlled and sufficiently scaled trials are imperative in order to establish micafungin as a reliable and safe option in clinical practice.

Recent advances in antifungal chemotherapy

For over 50 years, amphotericin B deoxycholate (AmBD) has been the 'gold standard' in antifungal chemotherapy, despite its frequent toxicities. However, improved treatment options for invasive fungal infections (IFIs) have been developed during the last 15 years. Newer antifungal agents, including less toxic lipid preparations of AmBD, triazoles and the echinocandins, have been added to our armamentarium against IFIs. Some of these newer drugs can now replace AmBD as primary therapy (e.g. caspofungin for candidiasis, voriconazole for aspergillosis), whilst others offer new therapeutic options for difficult-to-treat IFIs (e.g. posaconazole for zygomycosis, fusariosis and chromoblastomycosis). It is interesting that extended use of newer antifungals such as fluconazole, despite decreasing the mortality attributed to candidiasis, resulted in selection of species resistant to several antifungals (Candida krusei, Candida glabrata); whilst several publications suggest that prolonged use of voriconazole may expose severely immunocompromised patients to the risk of zygomycosis (breakthrough). On the other hand, the differences in the mode of action of newer antifungals such as echinocandins raise the question whether combination antifungal therapy is more effective than monotherapy. Finally, the availability of an oral formulation with excellent biosafety of several newer antifungals (e.g. posaconazole) makes them candidates for prophylactic or prolonged maintenance therapy.

A comparative evaluation of properties and clinical efficacy of the echinocandins

With the increase in prevalence of fungal infections, newer antifungal agents are needed to effectively treat invasive disease, and at the same time minimize adverse effects from therapy. The echinocandins comprise a novel class of antifungals; their mechanism of action involves inhibiting 1,3-beta-D-glucan synthase, which is essential in cell wall synthesis for certain fungi. All three echinocandins are US FDA-approved for the treatment of esophageal candidiasis. Caspofungin and anidulafungin are licensed for the treatment of candidemia, and other select forms of invasive candidiasis. Micafungin is at present the only echinocandin approved for prophylaxis of fungal infections in hematopoietic stem cell transplants; whereas caspofungin is approved for empiric therapy of febrile neutropenia. Although all three echinocandins are active against Aspergillus, only caspofungin is presently approved for salvage therapy in invasive aspergillosis. Combination therapy with echinocandins plus other licensed antifungal therapy shows promise in treating invasive aspergillosis. This article will explore the similarities and differences among the echinocandins.

Nongastroesophageal reflux disease-related infectious, inflammatory and injurious disorders of the esophagus

PURPOSE OF REVIEW

To review recently published studies presenting novel and relevant information on some esophageal infectious, inflammatory and injurious diseases.

RECENT FINDINGS

In the treatment of Candida esophagitis, fluconazole remains the treatment of choice, but clinical failures indicate new therapeutic opportunities, like two new echinocandins, micafungin and anidulafungin. Eosinophilic esophagitis is an increasingly recognized entity. New therapeutic insights come from a six-food elimination diet in children and from fluticasone propionate in adults; humanized monoclonal IgG antibody anti-interlukin-5, mepolizumab, has been shown to decrease eosinophilia and ameliorate symptoms. There has been some advance in microscopic characterization of lymphocytic esophagitis. Esophagitis is found to be present in 67% of patients with pemphigo vulgaris, in 32.3% of patients with systemic sclerosis and to be associated with thoracic neoplasias. In the case of caustic ingestion, endoscopic ultrasound with miniprobes has proven not to be better than videoendoscopy. Recent evidence shows that systemic steroids might even be harmful. Mitomycin C applied on fresh wounds is currently being evaluated. Stenting of the stricture has been proposed for contrasting esophageal remodeling.

SUMMARY

These recent findings, together with a better understanding of diseases such as eosinophilic or lymphocytic esophagitis, allow new diagnostic and therapeutic approaches.

The echinocandin micafungin: a review of the pharmacology, spectrum of activity, clinical efficacy and safety

Micafungin is a relatively broad-spectrum antifungal agent available for clinical use in the US and Japan. By inhibiting the production of beta-1,3-glucan, an essential fungal cell wall component, micafungin has reduced toxicity to mammalian cells while maintaining potent antifungal activity against many pathogenic fungi including polyene- and azole-resistant isolates. Indeed, micafungin has been shown to be efficacious in the treatment of infections caused by Candida and Aspergillus species in clinical trials without the associated toxicities of amphotericin B formulations and drug interactions that occur with the azoles. In this review, the pharmacology, spectrum of activity, clinical efficacy and safety profile of micafungin are discussed.

Micafungin versus liposomal amphotericin B for candidaemia and invasive candidosis: a phase III randomised double-blind trial

BACKGROUND

Invasive candidosis is increasingly prevalent in seriously ill patients. Our aim was to compare micafungin with liposomal amphotericin B for the treatment of adult patients with candidaemia or invasive candidosis.

METHODS

We did a double-blind, randomised, multinational non-inferiority study to compare micafungin (100 mg/day) with liposomal amphotericin B (3 mg/kg per day) as first-line treatment of candidaemia and invasive candidosis. The primary endpoint was treatment success, defined as both a clinical and a mycological response at the end of treatment. Primary analyses were done on a per-protocol basis. This trial is registered with ClinicalTrials.gov, number NCT00106288.

FINDINGS

264 individuals were randomly assigned to treatment with micafungin; 267 were randomly assigned to receive liposomal amphotericin B. 202 individuals in the micafungin group and 190 in the liposomal amphotericin B group were included in the per-protocol analyses. Treatment success was observed for 181 (89.6%) patients treated with micafungin and 170 (89.5%) patients treated with liposomal amphotericin B. The difference in proportions, after stratification by neutropenic status at baseline, was 0.7% (95% CI -5.3 to 6.7). Efficacy was independent of the Candida spp and primary site of infection, as well as neutropenic status, APACHE II score, and whether a catheter was removed or replaced during the study. There were fewer treatment-related adverse events--including those that were serious or led to treatment discontinuation--with micafungin than there were with liposomal amphotericin B.

INTERPRETATION

Micafungin was as effective as--and caused fewer adverse events than--liposomal amphotericin B as first-line treatment of candidaemia and invasive candidosis.

[Systemic antifungals. Pharmacodynamics and pharmacokinetics]

Invasive fungal infections are important causes of morbidity and mortality in critically ill non neutropenic patients. For many years, amphotericin B and flucytosine have been the only available antifungal agents for invasive fungal infections. Fortunately, the antifungal armamentarium has increased during the past two decades with the addition of several new agents. In addition to itraconazole and fluconazole, lipid formulations of amphotericin B, voriconazole, and caspofungin have been recently licensed. These various antifungal agents differ in their pharmacokinetic and pharmacodynamic profile.

Antifungal therapy in children with invasive fungal infections: a systematic review

Invasive fungal infections are associated with significant morbidity and mortality. Differences between children and adults are reported, yet few trials of antifungal agents have been performed in pediatric populations. We performed a systematic review of the literature to guide appropriate pediatric treatment recommendations. From available trials that compared antifungal agents in either prolonged febrile neutropenia or invasive candidal or Aspergillus infection, no clear difference in treatment efficacy was demonstrated, although few trials were adequately powered. Differing antifungal pharmacokinetics between children and adults were demonstrated, requiring dose modification. Significant differences in toxicity, particularly nephrotoxicity, were identified between classes of antifungal agents. Therapy needs to be guided by the pathogen or suspected pathogens, the degree of immunosuppression, comorbidities (particularly renal dysfunction), concurrent nephrotoxins, and the expected length of therapy.

The Echinocandins

The changing pattern in fungal infections has driven the need to expand the targets of antifungal activity. The echinocandins are the newest addition to the arsenal against fungal infections. Three echinocandins have been approved by the United States Food and Drug Administration: caspofungin, micafungin, and anidulafungin. These agents have a broad spectrum of activity and are similar to each other with respect to in vitro activity against Candida sp, with micafungin and anidulafungin having similar minimum inhibitory concentrations (MICs) that are generally lower than the MIC of capsofungin. The MICs of the echinocandins are highest against Candida parapsilosis; however, whether this will affect clinical outcomes is unknown. Several case reports have identified clinical failure due to elevated MICs with caspofungin or micafungin against Candida albicans, Candida krusei, and C. parapsilosis. Resistance to the echinocandin class was present in some but not all of the isolates. Empiric therapy with one of the echinocandins for candidemia or invasive candidiasis in patients with neutropenia and those without neutropenia appears to be appropriate when one factors in mortality rate, the increasing frequency of non-albicans Candida infections, and the broad spectrum, safety, and fungicidal effect of the echinocandins. After speciation of the organism, continued therapy with an echinocandin can and should be reevaluated. The echinocandins demonstrate similar in vitro and in vivo activity against Aspergillus sp, but only caspofungin is approved for treatment in patients who are intolerant of or refractory to other therapies. Voriconazole and amphotericin B have demonstrated synergy with the echinocandins. The clinical response to combination therapy has been variable; however, the mortality rate appears to be lower with combination therapy than monotherapy. Large controlled trials are needed to determine the role of combination therapy for invasive aspergillosis. Micafungin and anidulafungin generally have a lower frequency of adverse reactions compared with caspofungin. Phlebitis (3.5-25% of patients) and elevated liver enzyme levels (1-15%) occur more often with caspofungin compared with micafungin and anidulafungin (< 8%). Overall, the three echinocandins are relatively safe and effective agents for the treatment of Candida infections.

Micafungin: A New Echinocandin Antifungal

The echinocandins represent the newest class of antifungals to combat infections caused by Candida sp. Micafungin is an echinocandin recently approved by the United States Food and Drug Administration. It is indicated in adults for esophageal candidiasis and prophylaxis against candidal infections in hematopoietic stem cell transplant recipients. Micafungin exhibits in vitro fungicidal activity against Candida sp, including fluconazole-resistant isolates. Its in vivo efficacy is comparable to that of fluconazole in the treatment of esophageal candidiasis and superior to that of fluconazole for prophylaxis of invasive candidal infections. Because it is not significantly metabolized by the cytochrome P450 3A system, micafungin is associated with few drug interactions. Micafungin does not require adjustment in patients with renal and/or hepatic impairment, and it has been shown to be well tolerated in both adult and pediatric patients. Its efficacy against Candida sp, coupled with its overall safety and drug interaction profiles, makes it an attractive option in the treatment against esophageal candidiasis and prophylaxis against invasive candidal infections.

Clinical efficacy of micafungin for chronic pulmonary aspergillosis

The rising incidence of pulmonary aspergillosis is a major clinical concern. However, only a limited number of antifungal drugs are available in Japan that are effective for pulmonary Aspergillus infections. Micafungin (MCFG), a newly developed echinocandin family antifungal drug, has potent antifungal activity in vitro, but few reports detailing its clinical effectiveness have been published to date. A retrospective study was performed using data from nine patients (seven males and two females) with chronic invasive forms of pulmonary aspergillosis, who were treated with either MCFG alone or together with other antifungal drugs between April 2003 and March 2004. The overall efficacy of the treatments was evaluated in the terms of clinical, mycological, serological and radiological responses. The average age of the patients was 61.9 (20-83) years old. Four patients received only MCFG and the remaining five patients were treated with MCFG in combination with amphotericin B (AMB) only (1 patient), itraconazole (ITC) only (2 patients) or AMB backed up by ITC during AMB discontinuation periods (2 patients). The mean duration of MCFG administration was 59.2 (28-96) days. Overall, the treatment was judged to have been effective for seven of nine patients. No patient's condition deteriorated in response to treatment. Administration of MCFG alone was judged to have been effective in three of four patients. No notable adverse effects were documented during MCFG administration. These data suggest that MCFG may be an effective and safe antifungal drug for the treatment of chronic invasive forms of pulmonary aspergillosis.

The pharmacokinetics and safety of micafungin, a novel echinocandin, in premature infants

BACKGROUND

: Candidal fungal infection rates in neonates are increasing and are a significant cause of mortality, especially in low birth weight infants. Micafungin is an echinocandin that works by inhibiting 1,3-beta-D-glucan synthase, an enzyme responsible for fungal cell wall synthesis. The objective of this study was to determine the safety and pharmacokinetics of micafungin in premature infants.

METHODS

: This was a phase I, single-dose, multicenter, open-label, sequential-dose trial of intravenous micafungin investigating 3 doses (0.75 mg/kg, 1.5 mg/kg and 3.0 mg/kg) in 18 premature infants weighing >1000 g (n = 6 in each dosage group). A further 5 infants (500-1000 g) were enrolled in the 0.75 mg/kg dosage group only.

RESULTS

: The mean +/- standard deviation gestational age in the >1000 g dosage group was 26.4 +/- 2.4 weeks and, on entry, patients had one or more of a variety of underlying conditions, including sepsis, pneumonia and other infections caused by Candida or other species. Micafungin pharmacokinetics in preterm infants appears linear. However, premature infants >1000 g on average displayed a shorter half-life (8 hours) and a more rapid rate of clearance (approximately 39 mL/h per kg) compared with published data in older children and adults. All doses of micafungin were well tolerated and no serious drug-related adverse events were observed.

CONCLUSIONS

: Single doses of micafungin, ranging up to 3.0 mg/kg, appear well tolerated in premature infants weighing >1000 g. The drug's elimination half-life and total plasma clearance in preterm infants appear dissimilar to published values for these parameters in older children and adults. The reason(s) for this apparent difference remain to be investigated.

Developments in the treatment of candidiasis: more choices and new challenges

The incidence of oesophageal candidiasis, candidaemia and disseminated candidiasis has increased dramatically. In addition to the amphotericin B formulations and fluconazole, the echinocandins anidulafungin, caspofungin and micafungin and the newer triazoles posaconazole and voriconazole are in the last stages of development and are becoming available for the management of candidiasis. This review presents these new agents and addresses their role in the treatment of candidiasis. All new antifungal agents exhibit potent activity against Candida spp. and echinocandins are fungicidal against most Candida spp. but appear to be less potent against certain species, such as Candida parapsilosis and C. guilliermondii. Systemic antifungal therapy can now be individualised based on the severity of the infection, comorbid conditions and the Candida spp. causing the infection. Studies are needed to investigate the possible development of resistance and the efficacy of these antifungal agents against the more resistant Candida spp.

Echinocandins in the management of invasive fungal infections, part 1

PURPOSE

The chemistry, pharmacology, spectrum of activity, resistance, pharmacokinetics, pharmacodynamics, clinical efficacy, adverse effiects, drug interactions, dosage and administration, cost, and place in therapy of echinocandins are reviewed.

SUMMARY

Three echinocandins are currently available: caspofungin, micafungin, and anidulafungin. The principal mechanism of action of the echinocandins is the noncompetitive inhibition of beta-(1,3)-dglucan synthase, an essential component of the cell wall of many fungi that is not present in mammalian cells. Echinocandins exhibit fungicidal activity against Candida species, including triazole-resistant isolates, and fungistatic activity against Aspergillus species. While fungistatic against mold, echinocandins may hold promise for the treatment of these pathogens when given in combination with amphotericin B or broad-spectrum triazoles, such as voriconazole. To date, resistance to echinocandins has been reported in only two patients. Echinocandins exhibit concentration- dependent activity against Candida species. In clinical trials, caspofungin has demonstrated efficacy in treating candidemia, esophageal candidiasis, and febrile neutropenia. Micafungin has demonstrated efficacy as antifungal prophylaxis in hematopoietic stem cell transplant recipients and in the treatment of esophageal candidiasis. Anidulafungin received approved labeling from the Food and Drug Administration in February 2006. Clinical efficacy data will be forthcoming.

CONCLUSION

Echinocandins are fungicidal against yeast and fungistatic against mold. Their limited toxicity profile and minimal drug-drug interactions make them an attractive new option for the treatment of invasive fungal infections. Their cost may limit their use as initial therapy for patients with fungemia in medical centers or intensive care units with a high rate of triazoleresistant Candida infections.

New agents for the treatment of fungal infections: clinical efficacy and gaps in coverage

The incidence of fungal infections has increased globally, and the introduction of the newer triazoles and echinocandin antifungals is a more-than-welcome and long overdue development. In this report, we review the clinical trials evaluating the therapeutic efficacy of these new antifungal agents and examine possible gaps in coverage. Voriconazole has become the primary treatment for most forms of invasive aspergillosis in a number of centers, posaconazole offers a broad antifungal spectrum, and echinocandins are fungicidal against most Candida species. Moreover, the new agents are active against some fungi that are resistant to amphotericin B, may have a role in the management of fever and neutropenia, and provide exciting options for combination antifungal therapy. However, significant questions remain, including the management of breakthrough infections and treatment failures and the efficacy of the new antifungal agents against less common fungi.

Micafungin (FK463), alone or in combination with other systemic antifungal agents, for the treatment of acute invasive aspergillosis

BACKGROUND

Micafungin (FK463) is a new lipopeptide compound (echinocandin) with activity against Aspergillus and Candida species. This study evaluated the safety and efficacy of micafungin in patients with proven or probable invasive aspergillosis (IA).

METHODS

A multinational, non-comparative study was conducted to examine proven or probable (pulmonary only) Aspergillus species infection in a wide variety of patient populations. The study employed an open-label design utilizing micafungin alone or in combination with another systemic antifungal agent. Criteria for IA and therapeutic responses were judged by an independent panel.

RESULTS

Of the 331 patients enrolled, only 225 met diagnostic criteria for IA as determined by the independent panel and received at least one dose of micafungin. Patients included 98/225 who had undergone hematopoietic stem cell transplantation (HSCT) (88/98 allogeneic), 48 with graft versus host disease (GVHD), and 83/225 who had received chemotherapy for hematologic malignancy. A favorable response rate at the end of therapy was seen in 35.6% (80/225) of patients. Of those only treated with micafungin, favorable responses were seen in 6/12 (50%) of the primary and 9/22 (40.9%) of the salvage therapy group, with corresponding numbers in the combination treatment groups of 5/17 (29.4%) and 60/174 (34.5%) of the primary and salvage treatment groups, respectively. Of the 326 micafungin-treated patients, 183 (56.1%) died during therapy or in the 6-week follow-up phase; 107 (58.5%) deaths were attributable to IA.

CONCLUSIONS

Micafungin as primary or salvage therapy proved efficacious and safe in high-risk patients with IA, although patient numbers are small in the micafungin-only groups.

Micafungin: a new echinocandin

Micafungin, a potent inhibitor of 1,3-beta-D-glucan synthase, has become the second available agent in the echinocandins class that is approved for use in clinical practice. This agent shares with caspofungin an identical spectrum of in vitro activity against Candida albicans, non-albicans species of Candida, and Aspergillus species, as well as several but not all pathogenic molds. If anything, its in vitro activity appears to be superior to that of caspofungin, although the clinical relevance of this observation is unclear. The clinical role of micafungin appears to be similar to that of caspofungin, although clinical data are still lacking at this stage, with initial approval only for treatment of esophageal candidiasis and prophylaxis in subjects with neutropenia. Pharmacokinetic and pharmacodynamic studies and reports of adverse effects and safety have reported similar but not identical results to those of other agents in the echinocandin class. Factors such as acquisition costs and the potential for resistance development may be more relevant to its widespread use than in vitro and in vivo data comparisons with caspofungin.

A Multicenter Randomized Trial Evaluating Posaconazole versus Fluconazole for the Treatment of Oropharyngeal Candidiasis in Subjects with HIV/AIDS

BACKGROUND

Oropharyngeal candidiasis is the most common opportunistic infection among persons infected with human immunodeficiency virus (HIV). Use of some agents is hampered by lack of efficacy, emergence of resistance, adverse events, and need for intravenous administration. Posaconazole is an extended-spectrum triazole with potent in vitro activity against Candida species, including Candida albicans, Candida glabrata, and Candida krusei (including fluconazole-resistant strains).

METHODS

This multicenter, randomized, evaluator-blinded study of subjects with HIV infection and oropharyngeal candidiasis compared efficacy of posaconazole with that of fluconazole. Subjects received either 200 mg of posaconazole or fluconazole oral suspension on day 1, followed by 100 mg/day for 13 days. The primary study end point--clinical success (cure or improvement) on day 14--was evaluated for 329 subjects. Durability of clinical success was evaluated on day 42.

RESULTS

Three hundred fifty subjects received posaconazole (n = 178) or fluconazole (n = 172). Clinical success occurred in 155 (91.7%) of 169 posaconazole recipients and in 148 (92.5%) of 160 fluconazole recipients (95% confidence interval, -6.61% to 5.04%), indicating that posaconazole was not inferior to fluconazole. On day 14, mycological success was 68% in both arms, but by day 42, significantly more posaconazole recipients than fluconazole recipients continued to have mycological success (40.6% vs. 26.4%; P=.038). Fewer posaconazole recipients than fluconazole recipients experienced clinical relapse (31.5% vs. 38.2%). Adverse events were similar between treatment arms.

CONCLUSIONS

Results demonstrate that posaconazole was as effective as fluconazole in producing a successful clinical outcome. However, posaconazole was more effective in sustaining clinical success after treatment was stopped.