LB1580. Efficacy Assessment of MAT2203 Encochleated Oral Formulation of Amphotericin B, in the Neutropenic Mouse Model of Pulmonary Mucormycosis

BACKGROUND: Invasive mucormycosis (IM) is associated with high mortality and morbidity. MAT2203 is an encochleated oral formulation of amphotericin B which has been shown to be safe and effective against murine aspergillosis and murine cryptococcal meningoencephalitis. We sought to compare the efficacy of MAT2203 to liposomal amphotericin B (LAMB) treatment in a neutropenic mouse model of IM. METHODS: ICR mice were immunosuppressed with cyclophosphamide and cortisone acetate on days -2, -3 and +8, relative to infection with intratracheally instilled Rhizopus delemar 99-880 or M. circinelloides f. jenssenii DI15-131. Treatment with placebo (diluent control), oral MAT2203 (5 to 45 mg/kg, given qd or bid for 7 days) or LAMB (10 mg/kg, iv, qd for 4 days), began 16 h post infection. Survival (n=10-20/group from 1/2 experiments) through Day +21 and tissue fungal burden of lungs or brain (n=10/group) euthanized on Day +4 post infection (conidial equivalents using qPCR) served as a primary and secondary endpoint, respectively. RESULTS: For Rhizopus delemar infection, doses of MAT2203 5,15 mg/kg qd or 7.5 mg/kg bid, significantly prolonged median survival time (MST) and enhanced overall survival vs. placebo-treated mice (MST of 9 Days and 0% survival for placebo-treated mice vs. 13 Days, and 20-40% for MAT2203 doses, P< 0.05 by Log-Rank). Importantly, MAT2203 treatments were as effective as LAMB (MST of 16 days and overall survival of 45%). For mice infected with M. circinelloides, MAT2203 at 15 mg/kg, qd significantly prolonged MST and enhanced overall survival vs. placebo-treated mice (MST of 5 Days and 0% survival, for placebo-treated mice vs. 13.5 Days and 50% survival for MAT2203, P< 0.05). In both infection models MAT2203 treatment of 15 mg/kg or LAMB resulted in significant ∼1.0-1.5 log reduction and ∼2.0-2.2 log reduction in lung and brain fungal burden vs. placebo, respectively (Wilcoxon Rank Sum). CONCLUSION: MAT2203 demonstrated in vivo efficacy in treating R. delemar or M. circinelloides pulmonary infection in immunosuppressed mice, which was equivalent to the LAMB current standard of care. Continued investigation and development of MAT2203 as a novel, and oral formulation of amphotericin antifungal agent against mucormycosis is warranted. DISCLOSURES: Theresa Matkovits, PhD, Matinas BioPharma: Employee Jenel Cobb, PhD, Matinas BioPharma: Employee Raphael J. Mannino, PhD, Matinas BioPharma: Employee Ashraf S. Ibrahim, PhD, Matinas BioPharma: Advisor/Consultant|Matinas BioPharma: Grant/Research Support|SFunga: Grant/Research Support.