In Vitro and In Vivo Antifungal Profile of a Novel and Long-Acting Inhaled Azole, PC945, on Aspergillus fumigatus Infection

Abstract

The profile of PC945, a novel triazole antifungal designed for administration via inhalation, was assessed in a range of in vitro and in vivo studies. PC945 was characterized as a potent, tightly binding inhibitor of Aspergillus fumigatus sterol 14α-demethylase (CYP51A and CYP51B) activity (50% inhibitory concentrations [IC50s], 0.23 μM and 0.22 μM, respectively) with characteristic type II azole binding spectra. Against 96 clinically isolated A. fumigatus strains, the MIC values of PC945 ranged from 0.032 to >8 μg/ml, while those of voriconazole ranged from 0.064 to 4 μg/ml. Spectrophotometric analysis of the effects of PC945 against itraconazole-susceptible and -resistant A. fumigatus growth yielded IC50 (determined based on optical density [OD]) values of 0.0012 to 0.034 μg/ml, whereas voriconazole (0.019 to >1 μg/ml) was less effective than PC945. PC945 was effective against a broad spectrum of pathogenic fungi (with MICs ranging from 0.0078 to 2 μg/ml), including Aspergillus terreus, Trichophyton rubrum, Candida albicans, Candida glabrata, Candida krusei, Cryptococcus gattii, Cryptococcus neoformans, and Rhizopus oryzae (1 or 2 isolates each). In addition, when A. fumigatus hyphae or human bronchial cells were treated with PC945 and then washed, PC945 was found to be absorbed quickly into both target and nontarget cells and to produce persistent antifungal effects. Among temporarily neutropenic immunocompromised mice infected with A. fumigatus intranasally, 50% of the animals survived until day 7 when treated intranasally with PC945 at 0.56 μg/mouse, while posaconazole showed similar effects (44%) at 14 μg/mouse. This profile affirms that topical treatment with PC945 should provide potent antifungal activity in the lung.

Antifungal effects of PC945, a novel inhaled triazole, onCandida albicans-infected immunocompromised mice

“…This superior profile probably arises from several factors, including pharmacokinetics, physicochemical properties and unique pharmacological characteristics. As reported earlier, PC945 has been demonstrated to have a longer duration of action in bronchial epithelial cells and hyphae than voriconazole (29). Moreover, the molecule is retained within the lung, resulting in low systemic exposure after oral and face mask nebulization in a phase 1 study (NCT02715570) (40) (in preparation).…”

“…binding (29,30). PC945 has been shown to have potent in vitro and in vivo antifungal activity on A. fumigatus isolates with inhibition of the enzyme lanosterol 14α-demethylase (CYP51A1) and also demonstrated that topical once daily treatment of PC945 was highly effective versus fungal burden in lung tissue and several biomarkers (galactomannan, cytokines) in serum and bronchoalveolar lavage fluid (BALF) in temporarily neutropenic mice infected with A. fumigatus when compared with intranasally treated posaconazole and voriconazole.…”

“…auris (32) and limited isolates of Candida spp. (33). Thus, the aim of this study is to evaluate in vitro antifungal effects of PC945 by broth Table 1).…”

Effects of intranasally dosed posaconazole on fungal load and biomarkers in Aspergillus fumigatus infected immunocompromised mice

“…It is therefore difficult to interpret the different effects of two administration routes, although we found that both oral and intranasal treatment improved survival proportions similarly. However, we carefully optimised the intranasal volume (35 μL), and as previously reported, 19 35 μL of intranasal volume is expected for 60% of inoculum to deposit in lung. This means 40% of inoculum or treated posaconazole might be swallowed or stayed in nasal cavity, and therefore it cannot be ruled out that intranasally treated posaconazole was exposed systemically via gastrointestinal route or nasal route.…”

“…On the day of infection, spore counts were assessed by haemocytometer and the inoculum was adjusted to obtain a concentration of 1.67 × 10 8 spores mL −1 of physiological saline. To induce immunosuppression and neutropenia, A/J mice were dosed with hydrocortisone (Sigma H4881; 125 mg/kg, sc) on days 3, 2 and 1 before infection, and with cyclophosphamide (Sigma C0768; 250 mg/kg, ip) 2 days before infection as previously reported . On day 0, animals were infected with the spore suspension (30 μL, intranasally 15 μL into each nostril) under anaesthesia with 3% isoflurane.…”