Human respiratory syncytial virus (RSV) is a major cause of acute upper and lower respiratory tract infections. RFI-641 is a novel RSV fusion inhibitor with potent in vitro activity. In vivo efficacy of RFI was determined in an African green monkey model of RSV infection involving prophylactic and therapeutic administration by inhalation exposure. Inhalation was with an RFI-641 nebulizer reservoir concentration of 15 mg/ml for 15 minutes (short exposure) or 2 hours (long exposure). Efficacy and RFI-641 exposure was determined by collection of throat swabs, nasal washes and bronchial alveolar lavage (BAL) on selected days. The short-exposure group (15 minutes) exhibited no effect on the nasal, throat or BAL samples. The throat and nasal samples for the long-exposure group failed to show a consistent reduction in viral titers. RFI-641 2 hours exposure-treated monkeys showed a statistically significantly log reduction for BAL samples of 0.73-1.34 PFU/ml (P-value 0.003) over all the sampling days. Analysis indicates that the long-exposure group titer was lower than the control titer on day 7 and when averaged across days. The results of this study demonstrate the ability of RFI-641 to reduce the viral load of RSV after inhalation exposure in the primate model of respiratory infection.

The study supports the pulmonary and systemic safety of aerosolized CIS at expected lung dose levels/kg of up to 12 times greater than the average dose patients are receiving in the CYCLIST trial.

Cyclosporine inhalation solution has the potential to improve outcomes following lung transplantation by delivering high concentrations of an immunosuppressant directly to the allograft while minimizing systemic drug exposure and associated toxicity. The objective of these studies was to evaluate the potential toxicity of aerosolized cyclosporine formulated in propylene glycol when given by inhalation route to rats and dogs for 28 days. Sprague-Dawley rats received total inhaled doses of 0 (air), 0 (vehicle, propylene glycol), 7.4, 24.3, and 53.9 mg cyclosporine/kg/day. In a separate study, beagle dogs were exposed to 0, 4.4, 7.7, and 9.7 mg cyclosporine/kg/day. Endpoints used to evaluate potential toxicity of inhaled cyclosporine were clinical observations, body weight, food consumption, respiratory functions, toxicokinetics, and clinical/anatomic pathology. Daily administration of aerosolized cyclosporine did not result in observable accumulation of cyclosporine in blood or lung tissue. Toxicokinetic analysis from the rat study showed that the exposure of cyclosporine was approximately 18 times higher in the lung tissue compared to the blood. Systemic effects were consistent with those known for cyclosporine. There was no unexpected systemic toxicity or clinically limiting local respiratory toxicity associated with inhalation exposure to cyclosporine inhalation solution at exposures up to 2.7 times the maximum human exposure in either rats or dogs. There were no respiratory or systemic effects of high doses of propylene glycol relative to air controls. These preclinical studies demonstrate the safety of aerosolized cyclosporine in propylene glycol and support its continued clinical investigation in patients undergoing allogeneic lung transplantation.

The objective was to determine the respiratory toxicity of MAP0004, orally inhaled dihydroergotamine (DHE), via inhalation for six months. Forty beagle dogs (twenty females, twenty males) were treated by nose-only inhalation for 182 days. Groups 2 through 5 received MAP0004 (mean doses: 0.045, 0.154, 0.44, 0.825 mg/kg); Group 1 received vehicle only. Groups 1 through 4 received single thirty-minute exposures, whereas Group 5 was exposed twice daily for thirty minutes. Toxicity was assessed from clinical observations, objective evaluations, and clinical and anatomical pathology. Systemic effects were scabbing of ear tips in Groups 3, 4, and 5 and excessive salivation and emesis, observed in Group 5. No changes were observed in the lungs in any dose group. Minimal treatment-related microscopic changes were observed in the respiratory nasal epithelium only in Group 5. No plexiform, vascular media, or fibroproliferative changes in any heart valves were observed in any group. Expected systemic pharmacologic effects were observed only at MAP0004 target doses ≥ 0.224 mg/kg (achieved doses > 0.154 mg/kg), which was more than five times the maximum daily intravenous (IV) human clinical dose of DHE, and more than twenty times the systemic equivalent dose of MAP0004. The no-observed adverse effect level (NOAEL) was the achieved inhaled dose of 0.045 mg/kg, or four times the human clinical dose of MAP0004.