Single- and Multiple-Ascending Dose Study of the Safety, Tolerability, and Pharmacokinetics of the Polymyxin Derivative, SPR206
Carbapenem-resistant Acinetobacter baumannii and Enterobacterales are identified as urgent threats, and multidrug-resistant (MDR) Pseudomonas aeruginosa and extended-spectrum beta-lactamases (ESBL)-producing pathogens are identified as a serious threat by the Centers for Disease Control and Prevention (CDC). SPR206 is a novel polymyxin derivative with potent in vitro and in vivo activity against A. baumannii , P. aeruginosa , and multiple clinically important species of Enterobacterales, including multidrug- and extensively drug-resistant strains. This was a first-in-human (FIH) double-blind, placebo-controlled, single- and multiple ascending dose study of the safety, tolerability, and pharmacokinetics (PK) of SPR206 in 94 healthy subjects. Following IV administration (1 h infusion) at single doses of 10 mg to 400 mg and multiple doses of 25 mg to 150 mg q8h for 7 days and 100 mg q8h for 14 days, SPR206 was generally safe and generally well tolerated. While the incidence of adverse events increased with dose, most were of mild severity. Systemic exposure (C max and AUC) to SPR206 was approximately dose proportional, time to peak concentrations ranged from 1.1 to 1.3 hours, and half-life ranged from 2.4 to 4.1 hours. No appreciable accumulation occurred with repeated dosing of SPR206 and trough concentrations suggest that steady state was achieved by Day 2. Urinary excretion of unchanged SPR206 was dose dependent across single- (SAD) and multiple ascending dose (MAD) cohorts, and the percentage of dose excreted as SPR206 was up to >50%. Importantly, no evidence of nephrotoxicity was observed over 14 days of 100 mg q8h dosing of SPR206; a dosing regimen anticipated to exceed requirements for clinical efficacy.