RESTORE-IMI 1: A Multicenter, Randomized, Double-blind Trial Comparing Efficacy and Safety of Imipenem/Relebactam vs Colistin Plus Imipenem in Patients With Imipenem-nonsusceptible Bacterial Infections

Background

The β-lactamase inhibitor relebactam can restore imipenem activity against imipenem-nonsusceptible gram-negative pathogens. We evaluated imipenem/relebactam for treating imipenem-nonsusceptible infections.

Methods

Randomized, controlled, double-blind, phase 3 trial. Hospitalized patients with hospital-acquired/ventilator-associated pneumonia, complicated intraabdominal infection, or complicated urinary tract infection caused by imipenem-nonsusceptible (but colistin- and imipenem/relebactam-susceptible) pathogens were randomized 2:1 to 5–21 days imipenem/relebactam or colistin+imipenem. Primary endpoint: favorable overall response (defined by relevant endpoints for each infection type) in the modified microbiologic intent-to-treat (mMITT) population (qualifying baseline pathogen and ≥1 dose study treatment). Secondary endpoints: clinical response, all-cause mortality, and treatment-emergent nephrotoxicity. Safety analyses included patients with ≥1 dose study treatment.

Results

Thirty-one patients received imipenem/relebactam and 16 colistin+imipenem. Among mITT patients (n = 21 imipenem/relebactam, n = 10 colistin+imipenem), 29% had Acute Physiology and Chronic Health Evaluation II scores >15, 23% had creatinine clearance <60 mL/min, and 35% were aged ≥65 years. Qualifying baseline pathogens: Pseudomonas aeruginosa (77%), Klebsiella spp. (16%), other Enterobacteriaceae (6%). Favorable overall response was observed in 71% imipenem/relebactam and 70% colistin+imipenem patients (90% confidence interval [CI] for difference, –27.5, 21.4), day 28 favorable clinical response in 71% and 40% (90% CI, 1.3, 51.5), and 28-day mortality in 10% and 30% (90% CI, –46.4, 6.7), respectively. Serious adverse events (AEs) occurred in 10% of imipenem/relebactam and 31% of colistin+imipenem patients, drug-related AEs in 16% and 31% (no drug-related deaths), and treatment-emergent nephrotoxicity in 10% and 56% (P = .002), respectively.

Conclusions

Imipenem/relebactam is an efficacious and well-tolerated treatment option for carbapenem-nonsusceptible infections.

Clinical Trials Registration

NCT02452047.

An Evaluation of Treatment Patterns and Associated Outcomes Among Adult Hospitalized Patients With Lower-Risk Community-Acquired Complicated Intra-abdominal Infections: How Often Are Expert Guidelines Followed?

Background

Expert guidelines discourage use of antipseudomonal β-lactams and fluoroquinolones in lower-risk patients with community-acquired complicated intra-abdominal infection (CA cIAI). Compliance with these recommendations across US hospitals is unclear. This study sought to determine treatment patterns and associated outcomes among adult hospitalized lower-risk patients with CA cIAI.

Methods

A study using data from the Premier Healthcare Database (10/2015–12/2017) was performed. Inclusion criteria: age ≥18 years; hospitalized; had a cIAI at admission; and received antibiotics within the first 4 hospital days. Patients were excluded if they were high risk, were transferred from another health care facility, had a recent hospital admission, or received dialysis within 30 days of admission. Empiric antibiotic treatment patterns and associated outcomes were quantified.

Results

Overall, 46722 (66%) patients with cIAIs met the lower-risk CA IAI study criteria. Among lower-risk CA IAI patients, the mean (SD) age was 53.4 (18.2) years, and 71% had a Charlson Comorbidity Index score of 0. The most common diagnosis was acute appendicitis with peritonitis (59.7%). Among lower-risk CA IAI patients, 54% received piperacillin/tazobactam, 20% received a fluoroquinolone (FQ), 11% received ceftriaxone, and 7% received ampicillin/sulbactam. Overall, the median hospital length of stay was 4 days and median costs were $12345 USD. Nearly 90% of patients were discharged home, and <1% died. Outcomes were similar across all empiric treatments received.

Conclusions

Overuse of antipseudomonal β-lactams and fluoroquinolones was commonplace among lower-risk CA IAI patients. These findings can serve as the basis for an antimicrobial stewardship initiative in hospitals aspiring to reduce the use of broad-spectrum antibiotics.

Considerations in the Selection of Renal Dosage Adjustments for Patients with Serious Infections and Lessons Learned from the Development of Ceftazidime-Avibactam

An extensive clinical development program (comprising two phase 2 and five phase 3 trials) has demonstrated the efficacy and safety of ceftazidime-avibactam in the treatment of adults with complicated intra-abdominal infection (cIAI), complicated urinary tract infection (cUTI), and hospital-acquired pneumonia (HAP), including ventilator-associated pneumonia (VAP). During the phase 3 clinical program, updated population pharmacokinetic (PK) modeling and Monte Carlo simulations using clinical PK data supported modified ceftazidime-avibactam dosage adjustments for patients with moderate or severe renal impairment (comprising a 50% increase in total daily dose compared with the original dosage adjustments) to reduce the risk of subtherapeutic drug exposures in the event of rapidly improving renal function. The modified dosage adjustments were included in the ceftazidime-avibactam labeling information at the time of initial approval and were subsequently evaluated in the final phase 3 trial (in patients with HAP, including VAP), providing supportive data for the approved U.S. and European ceftazidime-avibactam dosage regimens across renal function categories. This review describes the analyses supporting the ceftazidime-avibactam dosage adjustments for renal impairment and discusses the wider implications and benefits of using modeling and simulation to support dosage regimen optimization based on emerging clinical evidence.

Use of doripenem and risk of seizure and renal impairment in US hospitalized patients: a retrospective cohort study

OBJECTIVES

A large retrospective database study was conducted to assess the incidence rate of treatment-emergent renal impairment/failure, seizure, and hemolytic anemia in doripenem and imipenem intravenous (IV)-exposed patients treated for complicated urinary tract infection (cUTI) and complicated intra-abdominal infection (cIAI) in US hospitals.

METHODS

Using the Premier Perspective™ Database (PPD), which maintains hospital discharge records for over 309 million patients, the incidence rate of treatment-emergent renal impairment/failure, seizure, and hemolytic anemia in the doripenem-treated compared with imipenem IV-treated population was examined.

RESULTS

The unadjusted doripenem rate ratio (RR) for renal impairment/failure relative to imipenem IV was 1.13 [95% confidence interval (CI) 1.07-1.21; p < 0.0001]. The unadjusted doripenem rate ratio for seizure relative to imipenem IV was 0.74 (95% CI 0.52-1.05; p = 0.07). In the comparative safety analysis, adjusted incidence rates of renal impairment/failure between doripenem-exposed patients and a propensity score-matched comparator cohort of imipenem IV-exposed patients showed no statistically significant difference in cUTI [RR = 1.02; 95% CI 0.93-1.12; p = 0.71] or cIAI (RR = 1.17; 95% CI 1.00-1.36; p = 0.05). Likewise, there was no statistically significant difference in adjusted incidence rates for seizures in doripenem-treated versus matched imipenem-treated patients for cUTI (RR = 0.69; 95% CI 0.41-1.14; p = 0.15) or cIAI (RR = 0.45; 95% CI 0.15-1.41; p = 0.17). No hemolytic anemia events were observed in this study.

CONCLUSIONS

In this large retrospective cohort study of US hospitalized patients, no statistically significant differences in the adjusted relative rates of renal impairment/failure and seizure were observed between doripenem and a propensity score-matched comparator cohort of imipenem IV patients in the treatment of cUTI and cIAI.

Ceftolozane/tazobactam and ceftazidime/avibactam: two novel β-lactam/β-lactamase inhibitor combination agents for the treatment of resistant Gram-negative bacterial infections

The rise in resistant Gram-negative bacteria is a major concern and has led to difficulty in treating multidrug-resistant (MDR) infections. Two recently approved combination antibiotics, ceftolozane/tazobactam and ceftazidime/avibactam, may be effective in treating these resistant infections. Ceftolozane is a novel cephalosporin that has been developed in combination with tazobactam, a recognised β-lactamase inhibitor (BLI). Avibactam is a novel BLI combined with ceftazidime, a cephalosporin with an established history. Both of these β-lactam/BLI combination agents have been shown to retain in vitro activity against selected resistant Gram-negative pathogens, including Enterobacteriaceae and Pseudomonas aeruginosa; notably, ceftazidime/avibactam has demonstrated consistent activity against Klebsiella pneumoniae carbapenemase (KPC)-producing organisms. Both agents have been approved for the indications of complicated intra-abdominal infection (with metronidazole) and complicated urinary tract infection, and have ongoing phase 3 trials for the treatment of ventilator-associated and nosocomial pneumonia. This manuscript will review current data available regarding the spectrum of activity and clinical trials that led to the US Food and Drug Administration (FDA) approval of these agents. Both agents appear to be well tolerated and show promise in the treatment of MDR Gram-negative infections.