The Fungal Cyp51 Specific Inhibitor VT-1598 Demonstrates In vitro and In vivo Activity against Candida auris [Experimental Therapeutics]

Candida auris is an emerging pathogen associated with significant mortality and often multi-drug resistance. VT-1598, a tetrazole-based fungal CYP51-specific inhibitor, was evaluated in vitro and in vivo against C. auris. Susceptibility testing was performed against 100 clinical isolates of C. auris by broth microdilution. Neutropenic mice were infected intravenously with C. auris, and treatment began 24 hours post-inoculation with vehicle control, oral VT-1598 (5, 15, and 50 mg/kg once daily), oral fluconazole (20 mg/kg once daily), or intraperitoneal caspofungin (10 mg/kg once daily), which continued for 7 days. Fungal burden was assessed in the kidneys and brains on day 8 in the fungal burden arm, and on the days the mice succumbed to infection or on day 21 in the survival arm. VT-1598 plasma trough concentrations were also assessed on day 8. VT-1598 demonstrated in vitro activity against C. auris, with a mode MIC of 0.25 μg/mL and MICs ranging from 0.03 to 8 μg/mL. Treatment with VT-1598 resulted in significant and dose-dependent improvements in survival (median survival 15 and >21 days for VT-1598 15 and 50 mg/kg, respectively) and reductions in kidney and brain fungal burden (1.88 to 3.61 log₁₀ CFU/g reduction) compared to control (5 days). The reductions in fungal burden correlated with plasma trough concentrations. Treatment with caspofungin, but not fluconazole, also resulted in significant improvements in survival and reductions in fungal burden compared to control. These results suggest that VT-1598 may be a future option for the treatment of invasive infections caused by C. auris.

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