PC945 is a novel antifungal agent developed as an inhalation therapy for the treatment of invasive pulmonary aspergillosis. In this study, we examined the effects of intranasally dosed PC945 on biomarkers and survival rates in Aspergillus fumigatus infected immunocompromised mice.
A/J mice (males, 5 weeks old) were dosed with hydrocortisone (125 mg/kg, sc,) on days 3, 2 and 1 before infection, and with cyclophosphamide (250 mg/kg, ip) 2 days before infection to induce temporary neutropenia. On day 0, animals were infected intranasally with 35 μL of the spore suspension of Aspergillus fumigatus (ATCC 13073) at a concentration of 1.67 × 108 spores mL-1 of physiological saline. PC945, posaconazole or voriconazole were given intranasally on days 0, 1, 2 and 3 (early intervention) or days 1, 2 and 3 (late intervention) and animals were culled 6 hours after the final treatment on day 3. Bronchoalveolar lavage fluid (BALF) and serum were collected for biomarker analysis. Alternatively, the survival of animals was observed for 7 days. Furthermore, the effects of extended prophylaxis treatment (treatment daily on days -7 to +3 or days -7 to 0) were investigated and compared with those of the other treatment regimens.
Early and late interventions with PC945 (0.08, 0.4, 2, 10 mg/ml isotonic saline suspension) were found to inhibit fungal load in the lung, and to decrease galactomannan concentrations in both BALF and serum in a dose-dependent manner. PC945 also inhibited inflammatory cell accumulation into BALF, IFNγ, IL-17 and malondialdehyde (MDA, an oxidative stress marker) levels in BALF, and TNFα and IL-6 levels in serum, all of which were elevated by Aspergillus fumigatus infection. Intra-nasal dosing with either posaconazole or voriconazole also inhibited infection, but neither compound was as potent as PC945. Either PC945 or posaconazole (0.4 mg/mL) was delivered intranasally once/daily from days 1 to 7 post infection, and “survival” was determined by death or ≥20% body weight reduction from day 1 post infection. 75% of mice treated PC945 were survived although posaconazole showed only 25% survival rate. Furthermore, the effects of extended prophylactic treatment with PC945 were evaluated. Extended prophylaxis with PC945 (0.016mg/ml, a 25 fold lower dose than used in biomarker study above) was found to inhibit fungal load in the lung, the galactomannan concentrations in both BALF and serum and cytokines more potently than treatment on days -1 to +3. Similarly, when evaluated on day 3 post infection, extended prophylactic treatment on days -7 to 0 generated superior anti-fungal effects than resulted from treatment on just days -1 and 0.
Intranasally dosed PC945 showed more potent inhibitory effects of fungal load, galactomannan concentrations and A. fumigatus-dependent inflammation than intranasal treatment with posaconazole or voriconazole. The data suggest that the anti-fungal effects in the lung of PC945 accumulate repeat dosing and that these effects are persistent. Thus, PC945 has the potential to be a novel inhaled therapy for the treatment of Aspergillus fumigatus infection in humans.