Efficacy of LY303366 against amphotericin B-susceptible and -resistant Aspergillus fumigatus in a murine model of invasive aspergillosis.

Abstract

LY303366 is a novel antifungal echinocandin with excellent in vitro activity against Aspergillus spp. We compared four doses (1, 2.5, 10, and 25 mg/kg of body weight) of LY303366 with amphotericin B (0.5 to 5 mg/kg) in a temporarily neutropenic murine model of invasive aspergillosis against an amphotericin B-susceptible (AF210) and an amphotericin B-resistant (AF65) Aspergillus fumigatus isolate based on in vivo response. Mice were immunosuppressed with cyclophosphamide (200 mg/kg) and infected 3 days later. Treatment started 18 h after infection and lasted for 10 days. LY303366 was given once daily intravenously for 10 days, and amphotericin B (at 0.5, 2, and 5 mg/kg) was given once daily intraperitoneally for 10 days, or only on days 1, 2, 4, and 7 (at 5 mg/kg). Kidneys and lungs from survivors were cultured on day 11. Control mice in both experiments had 90 to 100% mortality. Amphotericin B at 0.5 mg/kg and LY303366 at 1 mg/kg yielded 10 to 20% survival rates for mice infected with either AF210 or AF65. Amphotericin B at 2 and 5 (both regimens) mg/kg yielded a 70 to 100% survival rate for mice infected with AF210 but a 10 to 30% survival rate for mice infected with AF65 (P = 0.01 to 0.04 compared with AF210). Against AF210 and AF65, LY303366 at 2.5, 10, and 25 mg/kg produced a survival rate of 70 to 80%, which was as effective as amphotericin B for AF210, but superior to amphotericin B for AF65 (P < 0.03 to 0.0006). For AF65, LY303366 at 10 and 25 mg/kg/day was superior to amphotericin B at 2 and 5 mg/kg/day in reducing tissue colony counts (P = 0.01 to 0.003), and for AF210, amphotericin B at 5 mg/kg/day and at 5 mg/kg in four doses was more effective than all four regimens of LY303366 in reducing renal culture counts (P = 0.01 to 0.0001). The present study shows, for the first time, that in vivo resistance of A. fumigatus to amphotericin B exists, although this could not be detected by in vitro susceptibility assays. Furthermore, LY303366 appears to be effective against amphotericin B-susceptible and -resistant A. fumigatus infection in this model and should be further evaluated clinically.

• Authors: P E Verweij, K L Oakley, J Morrissey, G Morrissey, D W Denning
• Journal: Antimicrobial agents and chemotherapy (Antimicrob Agents Chemother) Vol. 42 Issue 4 Pg. 873-8 (Apr 1998) ISSN: 0066-4804 [Print] United States
• PMID: 9559799 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Antifungal Agents
• Echinocandins
• Immunosuppressive Agents
• Peptides, Cyclic
• Amphotericin B
• Cyclophosphamide
• Anidulafungin

Topics

• Amphotericin B (pharmacology)
• Anidulafungin
• Animals
• Antifungal Agents (pharmacology, therapeutic use)
• Aspergillosis (drug therapy, microbiology)
• Aspergillus fumigatus (drug effects)
• Colony Count, Microbial
• Cyclophosphamide (pharmacology)
• Drug Resistance, Microbial
• Echinocandins
• Immunocompromised Host
• Immunosuppressive Agents (pharmacology)
• Male
• Mice
• Microbial Sensitivity Tests
• Neutropenia (microbiology)
• Peptides, Cyclic (therapeutic use)