232. Population Pharmacokinetics (PopPK) of Ceftazidime-Avibactam (CZA) in Combination with Aztreonam (ATM) in a Phase I, Open-Label Study in Healthy Adult Subjects (COMBINE)
Authors: Lodise Thomas , Nicholas O’Donnell J , Balevic Stephen , Liu Xing , Gu Kenan , George Jomy , Raja Shruti , Guptill Jeffrey , Zaharoff Smitha , Schwager Nyssa , Fowler Vance G , Chambers Henry 
Published: December 2022

Abstract

Background
Scant PK data are available with CZA-ATM in combination. Occurrence of ALT/AST elevations are common with ATM, and it is unknown if it is exacerbated by use of CZA-ATM. This analysis of COMBINE sought to describe the popPK of CZA-ATM and to assess the association between ATM exposures and ALT/AST elevations.

Methods
COMBINE was a Phase I study of 48 healthy subjects aged 18-45 years (NCT03978091). Subjects were enrolled into 1 of 6 Cohorts (Table 1). Drug(s) were administered for 7 D and intensive plasma and urine PK sampling was performed. PopPK models were developed for ceftazidime (CAZ), avibactam (AVI), and ATM. Empirical Bayesian estimates from the ATM PopPK model were used to simulate ATM day 1 (D1) exposures. Associations between D1 ATM exposures and highest observed ALT/AST were assessed with curvilinear regression (CR) and generalized linear models (GLM).

Results
Of enrolled 48 subjects, 35% had ALT/AST elevations; 94% occurred in ATM/CZA-ATM Cohorts. Two severe study product related ALT/AST AEs were observed with in the continuous infusion (CI) ATM Cohort. All subjects with ALT/ATS elevations were asymptomatic with no other signs of liver injury. In the ATM PopPK model, CZA-ATM administration reduced ATM non-renal clearance (CLNR) by 1 L/hr (16% of total CL) (Table 2). Administration of CAZ-ATM had a negligible effect on total CAZ CL in the CAZ PopPK model and CZA-ATM was not a covariate in final AVI PopPK model. In the CR, no ATM exposure-ALT/AST associations were identified in overall analyses. Associations (R2=0.18-0.22, p&lt; 0.05) between D1 AUC and ALT/AST were observed in CR analyses restricted to the intermittent infusion (II) ATM Cohorts (Figure 1). In GLM, D1 AUC was significantly associated with ALT/AST in the ATM II Cohort analyses. Administration of CZA-ATM was not associated with ALT/AST in the GLM analyses. Figure 1

Conclusion
Administration of CZA-ATM was found to reduce ATM CL, resulting in higher daily ATM AUCs, but did not exacerbate AST/ALT elevations relative to ATM alone. The observed association between ATM AUC and ALT/AST elevations in subjects who received II ATM suggest the risks vs benefits of using II of ATM 8 g/daily vs 6 g/daily with CZA should be considered. Use of CI ATM should be used with caution given the 2 severe ALT/ASTs in the CI ATM Cohort.

Disclosures
Thomas Lodise, Jr., Pharm.D., PhD, BioFire Diagnostics: Grant/Research Support|cidara: Advisor/Consultant|cidara: Honoraria|Entasis: Grant/Research Support|Merck: Advisor/Consultant|Merck: Grant/Research Support|Paratek: Advisor/Consultant|Shionogi: Advisor/Consultant|Spero: Advisor/Consultant|Venatrox: Advisor/Consultant J Nicholas O'Donnell, Pharm.D., Merck & Co, Inc: Grant/Research Support|Paratek Pharmaceuticals: Grant/Research Support Stephen Balevic, MD, Purdue Pharma: Grant/Research Support|UCB: Advisor/Consultant Jeffrey Guptill, MD, argenx: Stocks/Bonds Vance G. Fowler, Jr, MD, MHS, Affinergy: Grant/Research Support|Affinergy: Honoraria|Affinium: Honoraria|Amphliphi Biosciences: Honoraria|ArcBio: Stocks/Bonds|Basilea: Grant/Research Support|Basilea: Honoraria|Bayer: Honoraria|C3J: Honoraria|Cerexa/Forest/Actavis/Allergan: Grant/Research Support|Contrafect: Grant/Research Support|Contrafect: Honoraria|Cubist/Merck: Grant/Research Support|Debiopharm: Grant/Research Support|Deep Blue: Grant/Research Support|Destiny: Honoraria|Genentech: Grant/Research Support|Genentech: Honoraria|Integrated Biotherapeutics: Honoraria|Janssen: Grant/Research Support|Janssen: Honoraria|Karius: Grant/Research Support|Medicines Co.: Honoraria|MedImmune: Grant/Research Support|MedImmune: Honoraria|NIH: Grant/Research Support|Novartis: Grant/Research Support|Novartis: Honoraria|Pfizer: Grant/Research Support|Regeneron: Grant/Research Support|Regeneron: Honoraria|Sepsis diagnostics: Sepsis diagnostics patent pending|UpToDate: Royalties|Valanbio: Stocks/Bonds henry chambers, MD, Merck: DSMB member|Merck: Stocks/Bonds|Moderna: Stocks/Bonds.