1285. Outcomes in Patients with Gram-Negative Bacteremia from Phase 2 and Phase 3 Clinical Trials of Cefiderocol, a Novel Siderophore Cephalosporin

Abstract Background Cefiderocol (CFDC) is the first siderophore cephalosporin approved (US and EU) for a broad range of infections caused by Gram-negative (GN) bacteria, including carbapenem-resistant Enterobacterales (ENT) and non-fermenters (NFs). Bacteremia is a serious manifestation of GN infection and understanding how well an antibiotic works to clear the bacteremia is an important part of drug evaluation. Methods All completed clinical studies for CFDC development were used to identify patients with GN bacteremia. Information collected included the primary infection site, species identification and antibiotic susceptibility, post randomization blood cultures and clinical and bacteremia outcome. In patients with missing data (blood cultures) clinical response of cure was used to impute microbiological eradication. Indeterminate responses resulted from a combination of missing data and clinical failure, including death prior to test of cure (TOC). Results Three clinical studies randomized 900 patients (CFDC 552; comparators 348) of whom 84 (CFDC 52; comparators 32) had GN bacteremia at baseline (Table). Bacteremia rate by study was CREDIBLE-CR 25.3%, APEKS-cUTI 6.2%, APEKS-NP 6.0%. Escherichia coli (29), Klebsiella pneumoniae (23) and Acinetobacter spp (21) were most frequent species. Sources included urinary tract (31), lung (22), unknown (10), IV line (8), intraabdominal (6), or other (7). Persistence of bacteremia at TOC was seen in 2/52 (3.8%) CFDC and 2/32 (6.2%) control patients (Table), usually due to lack of source control. Clinical outcomes varied by study and infection source and were often confounded (indeterminate response). Eradication in patients with ENT at TOC was determined for 27/39 (69%) for CFDC and 16/23 (70%) for controls, and for 9/16 (56%) for CFDC and 10/11 (91%) for controls in patients with NFs, respectively. Table. Clinical and bacteremia microbiological outcomes per patient at TOC. Conclusion Post-treatment negative blood cultures were inconsistently collected, especially in APEKS-NP and -cUTI, however, negative blood cultures on therapy without recurrence was seen in 96% of CFDC patients with sufficient information. A dedicated clinical trial in GN bacteremia (GAME CHANGER; NCT03869437) is ongoing and will better delineate microbiological outcomes. Disclosures David Paterson, Accelerate (Speaker’s Bureau)BioMerieux (Speaker’s Bureau)BioMerieux (Advisor or Review Panel member)Entasis (Advisor or Review Panel member)Merck (Advisor or Review Panel member)Merck (Grant/Research Support)Merck (Speaker’s Bureau)Pfizer (Speaker’s Bureau)Shionogi & Co., Ltd. (Grant/Research Support)VenatoRx (Advisor or Review Panel member) Masahiro Kinoshita, MPharm, Shionogi & Co., Ltd. (Employee) Kiichiro Toyoizumi, PhD, Shionogi & Co., Ltd. (Employee) Yuko Matsunaga, MD, Shionogi Inc. (Employee) Roger Echols, MD, Shionogi Inc. (Consultant)