Relationship between anti-fungal effects and lung exposure of PC945, a novel inhaled antifungal agent, in Aspergillus fumigatus infected mice: Pulmonary PK-PD analysis of anti-fungal PC945.

PC945 is a novel antifungal agent, optimised for inhaled treatment. In this study, the relationship between antifungal effects of PC945 and its exposure in the lungs was investigated in Aspergillus fumigatus intranasally infected, temporarily neutropenic mice. Mice were given prophylactic PC945 intranasally once daily (0.56 µg/mouse) on either Day -7 to 0 (8 doses) or Day -1 to 0 (2 doses). Lung tissue, plasma and bronchoalveolar lavage (BAL) fluid were collected 24 or 72 h post A. fumigatus inoculation for biomarker and pharmacokinetic analyses. BAL cell pellets and supernatants were prepared separately by centrifugation. 8 prophylactic doses of PC945 were found to demonstrate significantly stronger antifungal effects (lung fungal burden and galactomannan (GM) in BAL and plasma) than prophylaxis with 2 doses. PC945 concentrations were below the limit of detection in plasma but readily measured in lung extracts. The concentrations were much higher after extended prophylaxis (709 and 312 ng/g of lung) than short prophylaxis (301 and 195 ng/g of lung) at 24 and 72 h post last dose, respectively, suggesting PC945 accumulation in whole lung after repeat dosing although it was likely to be a mixture of dissolved and undissolved PC945, meaning that the data should be interpreted with caution. Interestingly, low concentrations of PC945 were detected in BAL supernatant (6.6 and 1.9 ng/ml) whereas high levels of PC945 were measured in BAL cell pellets (626 and 406 ng/ml) at 24 and 72 h post last dose, respectively, in extended prophylaxis. In addition, the PC945 concentrations in BAL cells showed a statistically significant correlation with measured anti-fungal activities. These observations will be pursued, and it is intended that BAL cell concentrations of PC945 be measured in future clinical studies rather than standard measurement in BAL itself. Thus, PC945's profile makes it an attractive potential prophylactic agent for the prevention of pulmonary fungal infections.

Safety and nonclinical and clinical pharmacokinetics of PC945, a novel inhaled triazole antifungal agent.

PC945 is a novel antifungal triazole formulated for nebulized delivery to treat lung Aspergillus infections. Pharmacokinetic and safety profiles from nonclinical studies and clinical trials in healthy subjects, and subjects with mild asthma were characterized. Toxicokinetics were assessed following daily 2-hour inhalation for 14 days. Potential for drug-drug interactions was evaluated using pooled human liver microsomes. Clinical safety and pharmacokinetics were assessed following (a) single inhaled doses (0.5-10 mg), (b) 7-day repeat doses (5 mg daily) in healthy subjects; (c) a single dose (5 mg) in subjects with mild asthma. Cmax occurred 4 hours (rats) or immediately (dogs) after a single dose. PC945 lung concentrations were substantially higher (>2000-fold) than those in plasma. PC945 only inhibited CYP3A4/5 substrate metabolism (IC50 : 1.33 µM [testosterone] and 0.085 µM [midazolam]). Geometric mean Cmax was 322 pg/mL (healthy subjects) and 335 pg/mL (subjects with mild asthma) 4-5 hours (median tmax ) after a single inhalation (5 mg). Following repeat, once daily inhalation (5 mg), Day 7 Cmax was 951 pg/mL (0.0016 µM) 45 minutes after dosing. Increases in Cmax and AUC0-24h were approximately dose-proportional (0.5-10 mg). PC945 administration was well tolerated in both healthy subjects and subjects with mild asthma. Treatment-emergent adverse events were mild/moderate and resolved before the study ended. No clinically significant lung function changes were observed. PC945 pharmacokinetics translated from nonclinical species to humans showed slow absorption from lungs and low systemic exposure, thereby limiting the potential for adverse side effects and drug interactions commonly seen with systemically delivered azoles.

Late therapeutic intervention with a respiratory syncytial virus L-protein polymerase inhibitor, PC786, on respiratory syncytial virus infection in human airway epithelium.

BACKGROUND AND PURPOSE: Effective anti-respiratory syncytial virus (RSV) agents are still not available for clinical use. Current major targets are virus surface proteins, such as a fusion protein involved in viral entry, but agents effective after RSV infection is established are required. Here we have investigated the effects of late therapeutic intervention with a novel inhaled RSV polymerase inhibitor, PC786, on RSV infection in human airway epithelium. EXPERIMENTAL APPROACH: Air liquid interface-cultured bronchial or small airway epithelium was infected with RSVA2. PC786 was applied apically or basolaterally once daily following peak virus load on Day 3 post inoculation. Apical wash was collected daily for determination of viral burden by PCR and plaque assay (primary endpoints) and biomarker analyses. The effects were compared with those of ALS-8112, an anti-RSV nucleoside analogue, and GS-5806, a fusion-protein inhibitor, which were treated basolaterally. KEY RESULTS: Late intervention with GS-5806 did not show significant anti-viral effects, but PC786 produced potent, concentration-dependent inhibition of viral replication with viral load falling below detectable limits 3 days after treatment commenced in airway epithelium. These effects were superior to those of ALS-8112. PC786 showed inhibitory activities against RSV-induced increases of CCL5, IL-6, double-strand DNA and mucin. The effects of PC786 were also confirmed in small airway epithelium. CONCLUSION AND IMPLICATIONS: Late therapeutic intervention with the RSV polymerase inhibitor, PC786, reduced the viral burden quickly in human airway epithelium. Thus, PC786 demonstrates the potential to be an effective therapeutic agent to treat active RSV infection.

Voriconazole Concentrations in Plasma and Epithelial Lining Fluid after Inhalation and Oral Treatment.

Adverse effects can compromise oral voriconazole treatment of pulmonary aspergillosis. Inhaled low-dose voriconazole may be an alternative treatment. In this study, six patients inhaled 40 mg voriconazole b.i.d. for 2 days, and six patients ingested 400 and 200 mg orally b.i.d. on day one and two, respectively. Blood samples were collected after the first inhalation, and bronchial alveolar lavage fluids and blood samples were collected for measurements of voriconazole 12 hr after the last administration. The concentration of voriconazole in epithelial lining fluid (ELF) was calculated by the urea dilution method. Voriconazole concentrations were detectable in plasma 15 min. after inhalation and declined at 30 and 60 min. Twelve hours after the last dose, median (95% CI) plasma voriconazole concentration was 8 (4-26) ng/mL in the inhalation group and 1224 (535-2341) ng/mL in the oral group (p < 0.0001). In ELF, median concentration was 190 (55-318) ng/mL and 8827 (4369-35172) ng/mL, respectively (p < 0.0001). Median ELF/plasma concentration ratio was 21 (6-63) in the inhalation group and 8 (3-20) in the oral group (p = 0.2). In conclusion, voriconazole is rapidly absorbed into the systemic circulation after inhalation. There was a non-significant trend towards a higher ELF/plasma concentration ratio in the inhalation group compared to the oral group.

First-in-human phase I dose escalation study of a second-generation non-ansamycin HSP90 inhibitor, AT13387, in patients with advanced solid tumors.

PURPOSE: AT13387 is a potent second-generation, fragment-derived HSP90 inhibitor. This phase I study investigated the maximum tolerated dose (MTD)/recommended phase II dose (RP2D) and safety, pharmacokinetic, and pharmacodynamic profiles of two AT13387 regimens in a refractory solid tumor population. EXPERIMENTAL DESIGN: Standard 3+3 dose escalation was used. MTD and RP2D determinations were based on the occurrence of dose-limiting toxicities (DLT) and overall toxicity, respectively. Pharmacokinetic parameters were measured after single and multiple doses. AT13387-mediated induction of HSP70 was evaluated in plasma, peripheral blood mononuclear cells, and paired tumor biopsies. RESULTS: Sixty-two patients were treated with doses ranging from 10 to 120 mg/m(2) twice weekly and 150 to 310 mg/m(2) once weekly (both for 3 weeks every 28 days). One DLT of visual disturbance occurred at 120 mg/m(2), which was considered the MTD and RP2D for the twice-weekly regimen. No formal DLTs occurred in the once-weekly regimen, but multiple moderately severe toxicities, including diarrhea, nausea, vomiting, fatigue, and systemic infusion reactions, led to selection of 260 mg/m(2) as the RP2D. Exposures of AT13387 increased proportionally with dose. Target engagement as measured by HSP70 induction occurred in plasma and tumor biopsy samples. One patient with gastrointestinal stromal tumor (GIST) who had progressive disease on imatinib had a partial response and remained on treatment for 10 months. Twenty-one patients (34%) had stable disease, which lasted >120 days in 7 patients. CONCLUSION: AT13387 administered once or twice weekly has an acceptable safety profile and demonstrated evidence of target engagement and preliminary antitumor activity.

A phase I and pharmacodynamic study of AT9283, a small-molecule inhibitor of aurora kinases in patients with relapsed/refractory leukemia or myelofibrosis.

BACKGROUND: This study sought to identify the maximum tolerated dose (MTD) of AT9283, an inhibitor of Aurora kinases A and B, in patients with relapsed or refractory leukemias. Other endpoints included pharmacokinetics, safety and tolerability, pharmacodynamics, and preliminary evidence of efficacy. PATIENTS AND METHODS: AT9283 was administered as a continuous 72-hour infusion every 21 days. Doses were escalated by a standard 3 + 3 design. After the MTD for the 72-hour infusion was identified, infusion duration was increased incrementally to 96 hours and 120 hours. In total, 48 patients received ≥ 1 cycle of AT9283. Median age was 61 years (range, 22-86 years); 56% were men; 75% were diagnosed with AML; and 89% had received ≥ 3 (up to 16) prior lines of therapy. RESULTS: 324 mg/m(2)/72 h AT9283 was determined to be the MTD. Dose-limiting toxicities (DLTs) were myocardial infarction, hypertension, cardiomyopathy, tumor lysis syndrome, pneumonia, and multiorgan failure. Other AT9283-related toxicities (non-DLT) included myelosuppression, predominantly leukopenia and mucositis. Bone marrow blasts decreased ≥ 38% after AT9283 treatment in approximately one-third of patients with relapsed/refractory AML; however, this effect was transient and no objective responses were achieved, despite evidence of Aurora kinase B inhibition. Two patients with accelerated-phase chronic myeloid leukemia showed evidence of benefit, manifested as a cytogenetic response in 1 case; 1 patient completed 6 cycles of treatment. Exposure to AT9283 was generally dose proportional. CONCLUSION: AT9283 tolerability was strongly dose-dependent, with reversible myelosuppression predominating at lower doses and events such as cardiovascular toxicities manifesting at higher doses. Clinical trials with AT9283 are ongoing in alternative patient populations.