cilofungin and Aspergillosis

The echinocandins are large lipopeptide molecules that are inhibitors of beta-(1,3)-glucan synthesis, an action that damages fungal cell walls. In vitro and in vivo, the echinocandins are rapidly fungicidal against most Candida spp and fungistatic against Aspergillus spp. They are not active at clinically relevant concentrations against Zygomycetes, Cryptococcus neoformans, or Fusarium spp. No drug target is present in mammalian cells. The first of the class to be licensed was caspofungin, for refractory invasive aspergillosis (about 40% response rate) and the second was micafungin. Adverse events are generally mild, including (for caspofungin) local phlebitis, fever, abnormal liver function tests, and mild haemolysis. Poor absorption after oral administration limits use to the intravenous route. Dosing is once daily and drug interactions are few. The echinocandins are widely distributed in the body, and are metabolised by the liver. Results of studies of caspofungin in candidaemia and invasive candidiasis suggest equivalent efficacy to amphotericin B, with substantially fewer toxic effects. Absence of antagonism in combination with other antifungal drugs suggests that combination antifungal therapy could become a general feature of the echinocandins, particularly for invasive aspergillosis.

Topics: Amphotericin B; Antifungal Agents; Aspergillosis; Candidiasis; Caspofungin; Clinical Trials as Topic; Echinocandins; Fungal Proteins; Humans; Lipopeptides; Lipoproteins; Micafungin; Peptides; Peptides, Cyclic; Treatment Outcome

The echinocandins are large lipopeptide molecules that are inhibitors of beta-(1,3)-glucan synthesis, an action that damages fungal cell walls. In vitro and in vivo, the echinocandins are rapidly fungicidal against most Candida spp and fungistatic against Aspergillus spp. They are not active at clinically relevant concentrations against Zygomycetes, Cryptococcus neoformans, or Fusarium spp. No drug target is present in mammalian cells. The first of the class to be licensed was caspofungin, for refractory invasive aspergillosis (about 40% response rate) and the second was micafungin. Adverse events are generally mild, including (for caspofungin) local phlebitis, fever, abnormal liver function tests, and mild haemolysis. Poor absorption after oral administration limits use to the intravenous route. Dosing is once daily and drug interactions are few. The echinocandins are widely distributed in the body, and are metabolised by the liver. Results of studies of caspofungin in candidaemia and invasive candidiasis suggest equivalent efficacy to amphotericin B, with substantially fewer toxic effects. Absence of antagonism in combination with other antifungal drugs suggests that combination antifungal therapy could become a general feature of the echinocandins, particularly for invasive aspergillosis.

Topics: Amphotericin B; Antifungal Agents; Aspergillosis; Candidiasis; Caspofungin; Clinical Trials as Topic; Echinocandins; Fungal Proteins; Humans; Lipopeptides; Lipoproteins; Micafungin; Peptides; Peptides, Cyclic; Treatment Outcome

(1,3)-beta-D-Glucan synthase is a cell wall synthesis enzyme that is the target of cilofungin, an antifungal agent of the lipopeptide class. Cilofungin's glucan synthase inhibitory activity, MIC, and effective dose 50% in a systemic infection mouse model tend to correlate for Candida albicans. This correlation is not seen in Aspergillus fumigatus. MICs for cilofungin against A. fumigatus were consistently > 125 micrograms/ml while the effective dose 50% in a systemic aspergillosis model was determined to be 20.6 mg/kg. To begin to understand this discrepancy, we examined the A. fumigatus glucan synthase. This cell wall enzyme was prepared and its activity was measured by [14C]-glucose incorporation from UDP-[U-14C]glucose into an acid insoluble polymer formed in the presence of alpha-amylase. Enzyme activity in crude membrane preparations was measured in the presence of several antifungal agents. Enzyme inhibition results showed that 1 microgram/ml of papulacandin B, echinochandin B, aculeacin A and cilofungin all inhibited A. fumigatus glucan synthase activity (40-71%) while 1 microgram/ml of amphotericin B, fluconazole, ketoconazole and nikkomycin did not affect enzyme activity. A correlation was therefore established between the inhibitory effect of cilofungin on the A. fumigatus glucan synthase and the effective dose 50% obtained in a systemic aspergillosis mouse model.

Topics: Amphotericin B; Animals; Aspergillosis; Aspergillus fumigatus; Dose-Response Relationship, Drug; Echinocandins; Fluconazole; Glucosyltransferases; Male; Membrane Proteins; Mice; Mice, Inbred Strains; Peptides, Cyclic; Schizosaccharomyces pombe Proteins; Species Specificity; Survival Analysis

Cilofungin, amphotericin B, and a combination of the two drugs were compared in a model of aspergillosis in immunocompetent mice in three experiments. Cilofungin was equivalent to amphotericin B in preventing death and eradicating cerebral aspergillosis, but it did not sterilize the kidneys. This is the first demonstration of the in vivo activity of cilofungin against any fungus other than Candida albicans. The mortality with combination therapy was higher than those with amphotericin B alone (P = 0.003) and cilofungin alone (P = 0.054), as was weight loss after infection, indicating antagonism between cilofungin and amphotericin B in this model. The mechanisms of action and antagonism remain to be explained.

Topics: Amphotericin B; Animals; Antifungal Agents; Aspergillosis; Aspergillus fumigatus; Drug Combinations; Echinocandins; Female; Kidney; Mice; Microbial Sensitivity Tests; Organ Size; Peptides; Peptides, Cyclic