Anidulafungin ? state of affairs from a clinical perspective

Anidulafungin--a new therapeutic option for Candida infections in liver transplantation

INTRODUCTION

In the last years, the incidence of Candida infections in liver transplant recipients has increased with still higher morbidity and mortality. Anidulafungin, a new echinocandin that does not interfere with cytochrome p450, shows no need for dosage adjustment based upon renal or hepatic function or weight.

AIM

To analyze tolerance to and microbiologic and clinical efficacy of Anidulafungin to treat Candida infections in liver transplant patients.

MATERIALS AND METHODS

This phase 3b, prospective, open-label, single-center study focused on liver transplant patients with a suspected and/or diagnosed Candida infection. The patients received Anidulafungin intravenously, optionally followed by oral therapy with azoles. The primary endpoint was the global response at the end of therapy; secondary endpoints were the efficacy of intravenous therapy, 90-day survival, as well as tolerance for and interaction with immunosuppresants.

RESULTS

We considered 42 consecutive liver recipients transplanted between 2009 and 2010 among whom 13 (31%) were recruited for the study and four patients were treated with Anidulafungin as empirical therapy, six as preemptive therapy, and three as targeted treatment for documented candidemia (7.1%). The immunosuppressive regimen consisted of tacrolimus and low dose of steroids. The Candida species were: C albicans (50%), C glabrata (12.5%), C parapsilosis (12.5%), C krusei (12.5%), C lusitaniae (6.2%), C tropicalis (6.2%), and multiple others (25%). The principle site of isolation was the bile (53.8%), followed by the bloodstream (23.1%), central venous catheters (15.4%), bronchoalveolar lavage (15.4%), peritoneum (7.7%), and other locations (7.7%). Two patients (15.4%) died of severe sepsis with multiple organ failure. There was no alteration of hepatic enzymes, indices of cholestasis or changes in immunosuppressant drug levels.

CONCLUSION

Anidulafungin was an effective, safe, and well-tolerated drug. There were neither toxic effects to the grafts or adverse interactions with immunosuppresants.

Treatment and prophylaxis of invasive candidiasis with anidulafungin, caspofungin and micafungin and its impact on use and costs: review of the literature

Invasive fungal infections are on the rise. Echinocandins are a relatively new class of antifungal drugs that act by inhibition of a key enzyme necessary for integrity of the fungal cell wall. Currently there are three available agents: caspofungin, micafungin and anidulafungin. While the individual echinocandin antifungals have a different spectrum of licensed indications, basically all of them are available for the treatment of candidemia and invasive candidiasis. Antifungal treatment modalities basically include in therapy for suspected or proven infection and prophylaxis. All three drugs are comparatively expensive. Therefore a systematic review of the literature was performed to investigate the following aspects: * General aspects of cost-effectiveness in the treatment of invasive fungal infections * Cost-effectiveness of the treatment with the above-mentioned antifungals * Cost-effectiveness in two settings: therapy and prophylaxis - Early initiation of antifungal therapy, adjustment after availability of microbiological results, duration of therapy, success and occurrence of severe complications (e.g. renal failure) are the most important cost drivers in antifungal therapy. - Considering the specific antifungals, for caspofungin the best evidence for cost-effectiveness is found in treatment of invasive candidiasis and in empiric therapy of suspected infections. Favourable economic data are available for micafungin as a cost-effective alternative to LAmB for prophylaxis in patients with hematopoietic stem cell transplantation (HSCT). For anidulafungin, cost-effectiveness was demostrated in a pharmacoeconomic model. Net savings - yet not significant - were observed in a retrospective chart review of 234 patients. Generally, however, most analyses are still based on pharmacoeconomic modelling rather than direct analysis of trial data or real-life clinical populations. - As an overall conclusion, using caspofungin, micafungin, or anidulafungin is not more expensive than using other established therapies. Micafungin has proven to be cost-effective in prophylaxis if the local fungal epidemiology indicates a high level of resistance to fluconazole. Switch strategies involving early initiation of broadly active therapy with switch to cheaper alternatives according to microbiology results and clinical status and early initiation of an appropriate therapy have been proven to be cost-efficient independent of the antifungal agent.

Anidulafungin for the treatment of invasive candidiasis

Candidaemia/invasive candidiasis (C/IC) is the most frequently occurring invasive fungal infection worldwide, with a particularly strong impact and high incidence in the intensive-care unit, where there is a need for new treatment options and strategies. The echinocandin anidulafungin has broad in vitro activity against a wide range of Candida species, along with favourable pharmacokinetics that allow administration in hepatic and renal impairment and with any comedication without the need for dose adjustments. The efficacy and safety of anidulafungin for the treatment of C/IC were demonstrated in a number of clinical studies and by some limited data from clinical practice. In a randomized comparative trial for the treatment of C/IC in adults, 76% of patients receiving anidulafungin and 60% of those given fluconazole were treated successfully (95% CI for difference: 4-27; p 0.01). Post hoc analyses suggest that anidulafungin is significantly more effective than standard-dose fluconazole for the treatment of candidaemia in critically ill patients. Anidulafungin is generally well tolerated, with commonly reported side effects including headache, hypokalaemia, gastrointestinal symptoms, abnormal liver function test results, and rash. In pharmaco-economic analyses, anidulafungin compared favourably with fluconazole (in terms of overall costs and hospital resource use) as well as with other echinocandins. Echinocandins, including anidulafungin, are now generally recommended as first-line therapy in moderately to severely ill patients, those with prior azole exposure, and patients with C/IC caused by Candida glabrata or Candida krusei.

[Role of anidulafungin in critically ill patients]

The most frequent invasive fungal infections in critically ill patients are invasive candidiasis, among which is candidemia. In the last few years, these infections have become more common in intensive care units (ICU), including those produced by species other than Candida albicans. This phenomenon may lead to the development of species resistant to antifungal agents. To start the most appropriate treatment, early diagnosis of the infection is essential, which would reduce empirical antibiotic treatment and increase the proportion of advanced or directed antibiotic therapy. Given the poor reliability of the available diagnostic techniques, new strategies are currently being employed in the ICU, such as the use of scores to evaluate the presence of fungal infections. The therapeutic arsenal against these infections has been increased and the introduction of anidulafungin represents the addition of a highly appropriate drug for the treatment of invasive candidiasis in immunocompetent critically ill patients.

[In vitro activity of amphotericin B and anidulafungin against Candida spp. biofilms]

Invasive infections caused by Candida spp. are increasing worldwide and are becoming an important cause of morbidity and mortality in immunocompromised patients. A large number of manifestations of candidiasis are associated with the formation of biofilms on inert or biological surfaces. Candida spp. biofilms are recalcitrant to treatment with conventional antifungal therapies. The aim of this study was dual 1) to determine the prevalence of biofilm producers among clinical isolates from catheter (16 C. albicans ) and blood culture (2 C. albicans and 30 C. tropicalis), and 2) to determine the activity of amphotericin B and anidulafungin against C. albicans and C. tropicalis biofilms of 24 and 48 hours of maturation. Biofilms were developed using a 96-well microtitre plate model and production and activity of antifungal agents against biofilms were determined by the tetrazolium (XTT) reduction assay. Of catheter and blood isolates, 62.5 and 56.25%, respectively, produced biofilms. By species, 68.42% of C. albicans and 53.33% of C. tropicalis were biofilm producers. C. albicans biofilms showed more resistance to amphotericin B and anidulafungin than their planktonic counterparts. Complete killing of biofilms was never achieved, even at the highest concentrations of the drugs tested. Anidulafungin displayed more activity than amphotericin B against C. albicans biofilms of 24 hours of maturation (GM MIC 0.354 vs. 0.686 microg/ml), but against C. tropicalis biofilms amphotericin B was more active (GM MIC 11.285 vs. 0.476 microg/ml). In contrast, against biofilms with 48 hours maturation, amphotericin B was more active against both species.

A Ser678Pro substitution in Fks1p confers resistance to echinocandin drugs in Aspergillus fumigatus

An S678P substitution in Fks1p, the major subunit of glucan synthase, was sufficient to confer echinocandin resistance in Aspergillus fumigatus. The equivalent mutation in Candida spp. has been implicated in echinocandin resistance. This work demonstrates that modification of Fks1p is a conserved mechanism for echinocandin resistance in pathogenic fungi.