1288. Phase 1 First-in-Human Single- and Multiple-Ascending Dose Trial Demonstrates Pharmacokinetics (PK) and Tolerability of SPR720, an Oral DNA GyrB Inhibitor for Mycobacterial Infections

Abstract Background SPR720 (phosphate pro-drug of SPR719) is a novel aminobenzimidazole bacterial DNA gyrase (GyrB) inhibitor in development for non-tuberculous mycobacterial lung disease (NTM-LD) and pulmonary tuberculosis. SPR719 has broad-spectrum activity versus clinically relevant mycobacteria in vitro and in murine and hollow fiber (HF) infection models. In this first-in-human single ascending dose (SAD) /multiple ascending dose (MAD) study, the safety, tolerability and pharmacokinetics (PK) of SPR720/SPR719 were evaluated in healthy volunteers. Methods This was a Phase 1 randomized, double-blind, placebo-controlled trial with 7 SAD cohorts (including a food effect cohort) and 5 MAD cohorts. Healthy volunteers (n=8/cohort, 3:1 randomization) received SPR720 or placebo in single oral doses of ranging from 100 mg to 2000 mg or repeat total daily doses ranging from 500 mg to 1500 mg for 7 or 14 days. Safety monitoring and PK sampling occurred throughout the trial. Plasma and urine concentrations of SPR720/SPR719 were measured by validated LC-MS/MS methods. PK parameters were calculated using non-compartmental analysis. Results A total of 96 subjects (including 8 healthy elderly subjects, age ≥ 65 years) were randomized and received study drug. SPR720 was well-tolerated at daily doses up to 1000 mg for up to 14 days. Across SAD/MAD cohorts, the most common adverse events were gastrointestinal (nausea, vomiting and diarrhea) and headache, all of mild or moderate severity and dose dependent. No serious adverse events were reported. Across SAD cohorts, a dose proportional and greater-than-dose proportional increase in SPR719 plasma Cmax and AUC0-24, respectively were observed. SPR720 was rapidly absorbed with a mean SPR719 t1/2 of 2.9-4.5 h. Dosing with food decreased SPR719 plasma AUC by ~20%. No clinically meaningful effect of age on plasma AUC was observed. In the MAD cohorts, SPR719 plasma exposure declined approximately 40% between Day 1 and Day 7, suggesting induction of an elimination pathway. However, plasma AUC0-24 was similar at Days 7 and 14. Conclusion Together with HF pharmacodynamic data, human PK and safety data for SPR720 suggest that predicted therapeutic exposures can be attained with a well-tolerated once-daily dose. Further evaluation in a Phase 2 NTM-LD trial is planned. Disclosures Angela Talley, MD, Spero Therapeutics (Employee, Shareholder) Archie Thurston, Jr., PhD, Spero Therapeutics (Consultant) Grayson Moore, BA, RN, Spero Therapeutics, Inc. (Shareholder, Independent Contractor) Vipul Kumar, PhD, Spero Therapeutics (Employee, Shareholder) Suzanne Stokes, PhD, Spero Therapeutics (Employee, Shareholder) Aaron Dane, MSc, Spero theraputics (Consultant) David Melnick, MD, Spero Therapeutics (Employee)Spero Therapeutics (Employee)