In Vitro and In Vivo Efficacy of a Novel and Long-Acting Fungicidal Azole, PC1244, on Aspergillus fumigatus Infection.

Thomas Colley,Mihiro Sunose,Genki Kimura,John King-Underwood,Stuart Onions,Matthew Crittall,Gurpreet Sehra,Josie E Parker,Franz Lagasse,Alan Naylor,Yasuo Kizawa,Garth Rapeport,Matthew Mcconville,Matthew C Fisher,Andrew G S Warrilow,Steven L Kelly,Alexandre Alanio,Stéphane Bretagne,Pete Strong,Anuradha Chowdhary,Jonathan Shannon,Kazuhiro Ito,Darius Armstrong‐James ,Damien Crépin ,Yoshihiro Nishimoto ,Diane Kelly ,John C Murray

doi:10.1128/aac.01941-17

Abstract

ABSTRACTThe antifungal effects of the novel triazole PC1244, designed for topical or inhaled administration, against Aspergillus fumigatus were tested in a range of in vitro and in vivo studies. PC1244 demonstrated potent antifungal activities against clinical A. fumigatus isolates (n = 96) with a MIC range of 0.016 to 0.25 μg/ml, whereas the MIC range for voriconazole was 0.25 to 0.5 μg/ml. PC1244 was a strong tight-binding inhibitor of recombinant A. fumigatus CYP51A and CYP51B (sterol 14α-demethylase) enzymes and strongly inhibited ergosterol synthesis in A. fumigatus with a 50% inhibitory concentration of 8 nM. PC1244 was effective against a broad spectrum of pathogenic fungi (MIC range, <0.0078 to 2 μg/ml), especially Aspergillus terreus, Trichophyton rubrum, Candida albicans, Candida glabrata, Candida krusei, Cryptococcus gattii, Cryptococcus neoformans, and Rhizopus oryzae. PC1244 also proved to be quickly absorbed into both A. fumigatus hyphae and bronchial epithelial cells, producing persistent antifungal effects. In addition, PC1244 showed fungicidal activity (minimum fungicidal concentration, 2 μg/ml) which indicated that it was 8-fold more potent than voriconazole. In vivo, once-daily intranasal administration of PC1244 (3.2 to 80 μg/ml) to temporarily neutropenic, immunocompromised mice 24 h after inoculation with itraconazole-susceptible A. fumigatus substantially reduced the fungal load in the lung, the galactomannan concentration in serum, and circulating inflammatory cytokine levels. Furthermore, 7 days of extended prophylaxis with PC1244 showed in vivo effects superior to those of 1 day of prophylactic treatment, suggesting accumulation of the effects of PC1244. Thus, PC1244 has the potential to be a novel therapy for the treatment of A. fumigatus infection in the lungs of humans.

Highlights

The antifungal effects of the novel triazole PC1244, designed for topical or inhaled administration, against Aspergillus fumigatus were tested in a range of in vitro and in vivo studies
It was observed that the concentrations of PC1244 needed to achieve the endpoints of 50% inhibition (50% inhibitory concentration [IC50]) and 90% inhibition (IC90) (IC50s and IC90s were determined from optical density [OD] measurements) were significantly lower than those of all reference compounds, including voriconazole (VRC), posaconazole (POS), and itraconazole (ITC), against ITC-susceptible A. fumigatus laboratory strains (NCPF2010, AF294, AF293) (Table 1) [22, 23]
In this report, we present data demonstrating that (i) the novel triazole PC1244 possesses both potent and persistent antifungal activity and significant fungicidal activity against ITC-susceptible and/or ITC-resistant A. fumigatus in vitro, (ii) the antifungal activity was confirmed in clinical isolates from two geographical areas, (iii) intranasal once-daily PC1244 treatment exhibits potent antifungal effects against A. fumigatus in vivo in temporarily neutropenic mice, and (iv) PC1244 shows a broad range of antifungal activity when screened against a panel of pathogenic fungal organisms

Summary

Introduction

The antifungal effects of the novel triazole PC1244, designed for topical or inhaled administration, against Aspergillus fumigatus were tested in a range of in vitro and in vivo studies. Serious unwanted effects in other organs have been reported after oral or systemic VRC and POS treatment, and exposure of the liver results in significant drug interactions arising from triazole inhibition of hepatic cytochrome P450 (CYP) enzymes [12, 13], the recent azoles isavuconazole and VT1161 showed better risk-benefit profiles in clinical or preclinical tests [14, 15]. Structural changes in the lung architecture, caused by chronic pulmonary disease or infection with M. tuberculosis, can lead to Aspergillus colonization of preexisting cavities, limiting the efficacy of orally administered compounds, which often struggle to penetrate into the pulmonary epithelial lining fluid [17]. The compound demonstrates activities comparable to those of POS and superior to those of VRC against both ITC-susceptible and -resistant strains, and it has been designed to have physicochemical properties suitable for topical administration to the lung and promote long-lasting tissue residency

Methods

Results

Conclusion