Efficacy of the Clinical Agent VT-1161 against Fluconazole-Sensitive and -Resistant Candida albicans in a Murine Model of Vaginal Candidiasis

Abstract

ABSTRACTVulvovaginal candidiasis (VVC) and recurrent VVC (RVVC) remain major health problems for women. VT-1161, a novel fungal CYP51 inhibitor which has potent antifungal activity against fluconazole-sensitiveCandida albicans, retained itsin vitropotency (MIC50of ≤0.015 and MIC90of 0.12 μg/ml) against 10 clinical isolates from VVC or RVVC patients resistant to fluconazole (MIC50of 8 and MIC90of 64 μg/ml). VT-1161 pharmacokinetics in mice displayed a high volume of distribution (1.4 liters/kg), high oral absorption (73%), and a long half-life (>48 h) and showed rapid penetration into vaginal tissue. In a murine model of vaginal candidiasis using fluconazole-sensitive yeast, oral doses as low as 4 mg/kg VT-1161 significantly reduced the fungal burden 1 and 4 days posttreatment (P< 0.0001). Similar VT-1161 efficacy was measured when an isolate highly resistant to fluconazole (MIC of 64 μg/ml) but fully sensitivein vitroto VT-1161 was used. When an isolate partially sensitive to VT-1161 (MIC of 0.12 μg/ml) and moderately resistant to fluconazole (MIC of 8 μg/ml) was used, VT-1161 remained efficacious, whereas fluconazole was efficacious on day 1 but did not sustain efficacy 4 days posttreatment. Both agents were inactive in treating an infection with an isolate that demonstrated weaker potency (MICs of 2 and 64 μg/ml for VT-1161 and fluconazole, respectively). Finally, the plasma concentrations of free VT-1161 were predictive of efficacy when in excess of thein vitroMIC values. These data support the clinical development of VT-1161 as a potentially more efficacious treatment for VVC and RVVC.