BACKGROUND:There is a need for additional therapeutic options for serious infections caused by Gram-negative pathogens. In the phase 3, descriptive REVISIT study, we investigated the safety and efficacy of aztreonam-avibactam in the treatment of complicated intra-abdominal infections or hospital-acquired pneumonia or ventilator-associated pneumonia (HAP-VAP) caused, or suspected to be caused, by Gram-negative bacteria. METHODS:This prospective, multinational, open-label, central assessor-masked study enrolled adults who were hospitalised with a complicated intra-abdominal infection or HAP-VAP. Patients were randomly allocated via block randomisation using interactive response technology stratified by infection type in a 2:1 ratio to aztreonam-avibactam (with metronidazole for complicated intra-abdominal infection) or meropenem with or without colistin for 5-14 days for complicated intra-abdominal infection or 7-14 days for HAP-VAP. The primary endpoint was clinical cure at the test-of-cure visit (within 3 days before or after day 28) in the intention-to-treat (ITT) population. Secondary endpoints included 28-day mortality in the ITT population and safety in patients in the ITT population who received study drug (safety analysis set). No formal hypothesis testing was planned. The study was registered with ClinicalTrials.gov (NCT03329092) and EudraCT (2017-002742-68) and is complete. FINDINGS:Between April 5, 2018, and Feb 23, 2023, we screened 461 patients. 422 patients were enrolled and randomly allocated (282 in the aztreonam-avibactam group and 140 in the meropenem group, forming the ITT analysis set), of whom ten patients (seven in the aztreonam-avibactam group and three in the meropenem group) were randomly allocated but did not receive study treatment. 271 (64%) of 422 patients had at least one Gram-negative pathogen from an adequate specimen identified at baseline. The most frequent baseline pathogens were Enterobacterales (252 [93%] of 271). Overall, 19 (24%) of 80 isolates tested for carbapenemases were carbapenemase-positive (serine, metallo-β-lactamase, or both). 193 (68·4%) of 282 patients in the aztreonam-avibactam group and 92 (65·7%) of 140 in the meropenem group had clinical cure at the test-of-cure visit (treatment difference 2·7% [95% CI -6·6 to 12·4]). For patients with complicated intra-abdominal infection, the adjudicated clinical cure rate was 76·4% (159 of 208) for the aztreonam-avibactam group and 74·0% (77 of 104) for the meropenem group. Cure rates in patients with HAP-VAP were 45·9% (34 of 74) for aztreonam-avibactam and 41·7% (15 of 36) for meropenem. 28-day all-cause mortality rates were 4% (12 of 282) for aztreonam-avibactam and 7% (ten of 140) for meropenem; in patients with complicated intra-abdominal infection, mortality was 2% (four of 208) and 3% (three of 104) for aztreonam-avibactam and meropenem, respectively, and in patients with HAP-VAP, mortality was 11% (eight of 74) and 19% (seven of 36), respectively. Aztreonam-avibactam was generally well tolerated, and safety findings were consistent with the known safety profile of aztreonam monotherapy. There were no treatment-related serious adverse events in the aztreonam-avibactam group. INTERPRETATION:These phase 3 efficacy and safety data provide support for aztreonam-avibactam as a potential therapeutic option for complicated intra-abdominal infection or HAP-VAP caused by Gram-negative bacteria. FUNDING:Pfizer.

A series of iterative population pharmacokinetic (PK) modeling and probability of target attainment (PTA) analyses based on emerging data supported dose selection for aztreonam-avibactam, an investigational combination antibiotic for serious Gram-negative bacterial infections. Two iterations of PK models built from avibactam data in infected patients and aztreonam data in healthy subjects with “patient-like” assumptions were used in joint PTA analyses (primary target: aztreonam 60

Abstract Background Multidrug resistant (MDR) Gram-negative bacteria, including metallo-β-lactamase (MBL) producers, pose significant treatment challenges. This study investigated efficacy and safety of aztreonam-avibactam (ATM-AVI) in the treatment of complicated intra-abdominal infection (cIAI) or hospital-acquired)/ventilator-associated pneumonia (HAP/VAP) due to Gram-negative bacteria, including MBL-producing MDR pathogens, with limited or no treatment options. Methods REVISIT was a phase 3, prospective, randomized, multicenter, open-label, central assessor-blinded study in hospitalized adults. Patients were randomized 2:1 to ATM-AVI (± metronidazole [MTZ]; cIAI patients only) or meropenem (MER) ± colistin (COL) for 5–14 (cIAI) or 7–14 (HAP/VAP) days. Clinical cure at the test-of-cure (TOC) visit in the intent-to-treat (ITT) and clinically evaluable (CE) analysis sets were the primary efficacy endpoints. Key secondary endpoints included microbiological responses at TOC, 28-day mortality, and safety. No formal hypothesis testing was planned. Results In total, 422 patients were randomized (ATM-AVI ± MTZ, n=282; MER ± COL, n=140). Adjudicated clinical cure rates at TOC are shown in Table 1. Favorable microbiological response rates at TOC (micro-ITT analysis set) were 75.7% for ATM-AVI ± MTZ and 73.9% for MER ± COL; 28-day all-cause mortality rates for ATM-AVI ± MTZ and MER ± COL were 1.9% (4/208) vs 2.9% (3/104), and 10.8% (8/74) vs 19.4% (7/36) in cIAI and HAP/VAP, respectively. Adverse events (AEs) are summarized in Table 2. There were no treatment-related serious AEs in the ATM-AVI group. Conclusion ATM-AVI (± MTZ) was effective in treating patients with cIAI and HAP/VAP, displaying similar efficacy to MER ± COL. ATM-AVI was generally well tolerated. These data support potential use of ATM-AVI for the treatment of serious infections caused by susceptible Gram-negative bacteria. Further analyses will focus on MBL-producing pathogens. Trial registration. NCT03329092. Study sponsored by Pfizer. ATM-AVI is jointly developed with AbbVie, also supported by the United States Biomedical Advanced Research and Development Authority (BARDA) and the European Innovative Medicines Initiative (IMI), under the COMBACTE-CARE consortium. Disclosures Yehuda Carmeli, MD, Merck: Advisor/Consultant|Merck: Grant/Research Support|Merck: Honoraria|Pfizer: Advisor/Consultant|Pfizer: Grant/Research Support|Pfizer: Honoraria|Qpex: Advisor/Consultant|Qpex: Grant/Research Support|Qpex: Honoraria|Roche: Advisor/Consultant|Roche: Grant/Research Support|Roche: Honoraria Georgios L. Daikos, PhD, MSD: Honoraria|Pfizer: Advisor/Consultant|Pfizer: Honoraria|Viatris: Honoraria Rosa-María Jiménez Rodríguez, MD, PhD, Abex: Honoraria|B. Braun: Honoraria|Johnson & Johnson: Honoraria Halley Rogers, MPH, Pfizer: Ownership Interest Michele Wible, MS, Pfizer: Ownership Interest Francis Arhin, PhD, Pfizer: Ownership Interest Joanne Leaney, PhD, Pfizer: Ownership Interest Rienk Pypstra, MD, MBA, Pfizer: Stocks/Bonds Joseph Chow, MD, Pfizer: Ownership Interest

Abstract Gonorrhea is a sexually transmitted infection for which antibiotic treatment options have declined due to increasing antibiotic resistance. Zoliflodacin, an investigational oral spiropyrimidinetrione antibiotic with activity against Neisseria gonorrhoeae strains that are multidrug‐resistant, including to third‐generation cephalosporins, is in phase III development for uncomplicated gonorrhea. This phase I, parallel, open‐label, randomized, crossover study in healthy adults evaluated the effect of food on the pharmacokinetics of single 3 or 4 g doses of zoliflodacin administered as granules for oral suspension in the fasted state or after consumption of a standardized high‐fat meal. Forty‐seven out of 48 randomized subjects completed the study. Oral administration of zoliflodacin with food delayed the absorption rate, compared with fasted state, with time to maximum concentration (Tmax) increasing from 3 to 6 h for the 3 g dose, and 2.5 to 4 h for the 4 g dose, but had no impact on the elimination of zoliflodacin. The maximum concentration (Cmax) and area under the plasma concentration‐time curve from time 0 to 24 h (AUC(0–24)) significantly increased with food by 52% and 94% for the 3 g dose, and by 89% and 108% for the 4 g dose. Forty‐two percent of participants reported a total of 34 treatment‐emergent adverse events (TEAEs), which were all considered mild in severity. Headache was the most common TEAE (22/48 subjects, 45.8%) and the only TEAE reported in more than one subject. In conclusion, administration of single 3 and 4 g doses of zoliflodacin as granules for oral suspension, with a high‐fat meal was well‐tolerated and resulted in statistically significant increases in peak and overall systemic exposure to zoliflodacin.

Objective Successful clinical trials are subject to recruitment. Recently, the REJUVENATE trial, a prospective phase 2a open-label, single-arm interventional clinical trial conducted within the Innovative Medicines Initiative-supported Combatting Bacterial Resistance in Europe-Carbapenem Resistance project, was published, with 85% of the recruitment performed in Spain. We analysed the recruitment success in this trial by establishing a model of recruitment practice. Methods A descriptive qualitative study was performed from May 2016 to October 2017 at 10 participating Spanish centres. Data were extracted from: (1) feasibility questionnaires to assess the centre’s potential for patient enrolment; (2) delegation of responsibility records; (3) pre-screening records including an anonymised list of potentially eligible and (4) screening and enrolment records. A descriptive analysis of the features was performed by the participating centre. Pearson’s and Spearman’s correlation coefficients were calculated to determine factors of recruitment success. Results The highest recruitment rate was observed in Hospitals 3 and 6 (58.8 and 47.0 patients per month, respectively). All the study teams were multidisciplinary with a median of 15 members (range: 7–22). Only Hospitals 3, 5 and 6 had dedicated nursing staff appointed exclusively to this study. Moreover, in those three hospitals and in Hospital 9, the study coordinator performed exclusive functions as a research planner, and did not assume these functions for the other hospitals. The univariate analysis showed a significant association between recruitment success and months of recruitment (p=0.024), number of staff (p<0.001), higher number of pharmacists (p=0.005), infectious disease specialists (p<0.001), the presence of microbiologist in the research team (p=0.018) and specifically dedicated nursing staff (p=0.036). Conclusions The existence of broad multidisciplinary teams with staff dedicated exclusively to the study as well as the implementation of a well-designed local patient assessment strategy were the essential optimisation factors for recruitment success in Spain. Trial registration number NCT02655419 ; EudraCT 2015-002726-39; analysis of pre-screened patients.

OBJECTIVES:To investigate pharmacokinetics (PK) and safety (primary objectives) and efficacy (secondary objective) of the investigational monobactam/β-lactamase inhibitor combination aztreonam/avibactam in patients with complicated intra-abdominal infection (cIAI). METHODS:This Phase 2a open-label, multicentre study (NCT02655419; EudraCT 2015-002726-39) enrolled adults with cIAI into sequential cohorts for 5-14 days treatment. Cohort 1 patients received an aztreonam/avibactam loading dose of 500/137 mg (30 min infusion), followed by maintenance doses of 1500/410 mg (3 h infusions) q6h; Cohort 2 received 500/167 mg (30 min infusion), followed by 1500/500 mg (3 h infusions) q6h. Cohort 3 was an extension of exposure at the higher dose regimen. Doses were adjusted for creatinine clearance of 31-50 mL/min (Cohorts 2 + 3). All patients received IV metronidazole 500 mg q8h. PK, safety and efficacy were assessed. RESULTS:Thirty-four patients (Cohort 1, n = 16; Cohorts 2 + 3, n = 18) comprised the modified ITT (MITT) population. Mean exposures of aztreonam and avibactam in Cohorts 2 + 3 were consistent with those predicted to achieve joint PK/pharmacodynamic target attainment in >90% patients. Adverse events (AEs) were similar between cohorts. The most common AEs were hepatic enzyme increases [n = 9 (26.5%)] and diarrhoea [n = 5 (14.7%)]. Clinical cure rates at the test-of-cure visit overall were 20/34 (58.8%) (MITT) and 14/23 (60.9%) (microbiological-MITT population). CONCLUSIONS:Observed AEs were consistent with the known safety profile of aztreonam monotherapy, with no new safety concerns identified. These data support selection of the aztreonam/avibactam 500/167 mg (30 min infusion) loading dose and 1500/500 mg (3 h infusions) maintenance dose q6h regimen, in patients with creatinine clearance >50 mL/min, for the Phase 3 development programme.