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Comparison of Treatment Outcomes between Analysis Populations in the RESTORE-IMI 1 Phase 3 Trial of Imipenem-Cilastatin-Relebactam versus Colistin plus Imipenem-Cilastatin in Patients with Imipenem-Nonsusceptible Bacterial Infections.

ABSTRACT: The RESTORE-IMI 1 phase 3 trial demonstrated the efficacy and safety of imipenem-cilastatin (IMI) combined with relebactam (REL) for treating imipenem-nonsusceptible infections. The objective of this analysis was to compare the outcomes among patients meeting eligibility requirements based on central laboratory susceptibility versus local laboratory susceptibility. Patients with serious infections caused by imipenem-nonsusceptible, colistin-susceptible, and imipenem-REL-susceptible pathogens were randomized 2:1 to IMI-REL plus placebo or colistin plus IMI for 5 to 21?days. The primary endpoint was a favorable overall response. Key endpoints included the clinical response and all-cause mortality. We compared outcomes between the primary microbiological modified intent-to-treat (mMITT) population, where eligibility was based on central laboratory susceptibility testing, and the supplemental mMITT (SmMITT) population, where eligibility was based on local, site-level testing. The SmMITT (n?=?41) and MITT (n?=?31) populations had similar baseline characteristics, including sex, age, illness severity, and renal function. In both analysis populations, favorable overall response rates in the IMI-REL treatment group were >70%. Favorable clinical response rates at day 28 were 71.4% for IMI-REL and 40.0% for colistin plus IMI in the mMITT population, whereas they were 75.0% for IMI-REL and 53.8% for colistin plus IMI in the SmMITT population. Day 28 all-cause mortality rates were 9.5% for IMI-REL and 30.0% for colistin plus IMI in the mMITT population, whereas they were 10.7% for IMI-REL and 23.1% for colistin plus IMI in the SmMITT population. The outcomes in the SmMITT population were generally consistent with those in the mMITT population, suggesting that outcomes may be applicable to the real-world use of IMI-REL for treating infections caused by imipenem-nonsusceptible Gram-negative pathogens. (This study has been registered at ClinicalTrials.gov under identifier NCT02452047.).

SUBMITTER: Kaye KS

PROVIDER: S-EPMC7179630 | biostudies-literature | 2020 Apr

REPOSITORIES: biostudies-literature

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Comparison of Treatment Outcomes between Analysis Populations in the RESTORE-IMI 1 Phase 3 Trial of Imipenem-Cilastatin-Relebactam versus Colistin plus Imipenem-Cilastatin in Patients with Imipenem-Nonsusceptible Bacterial Infections.

Kaye Keith S KS Boucher Helen W HW Brown Michelle L ML Aggrey Angela A Khan Ireen I Joeng Hee-Koung HK Tipping Robert W RW Du Jiejun J Young Katherine K Butterton Joan R JR Paschke Amanda A

Antimicrobial agents and chemotherapy 20200421 5

The RESTORE-IMI 1 phase 3 trial demonstrated the efficacy and safety of imipenem-cilastatin (IMI) combined with relebactam (REL) for treating imipenem-nonsusceptible infections. The objective of this analysis was to compare the outcomes among patients meeting eligibility requirements based on central laboratory susceptibility versus local laboratory susceptibility. Patients with serious infections caused by imipenem-nonsusceptible, colistin-susceptible, and imipenem-REL-susceptible pathogens wer ...[more]

PMID: 32094127

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Project description:Abstract Background Clinical trials of new antibacterial agents in patients with carbapenem-resistant infections are critical but challenging to conduct. One challenge is identifying the study population by microbiological (micro) criteria; patients need to be identified locally to initiate effective treatment rapidly, but data standardization requires central laboratory confirmation. REL is a novel ?-lactamase inhibitor that can restore imipenem activity against many imipenem-NS Gram-negative pathogens. Here we compare a supplemental analysis population based on local microbiology data (SmMITT eligibility) with the primary analysis population (mMITT) from the RESTORE-IMI 1 trial (NCT02452047) of IMI/REL vs. IMI+CST. Methods Randomized, active-controlled, double-blind, phase 3 trial enrolled adults with hospital-acquired/ventilator-associated bacterial pneumonia (HABP/VABP), complicated intra-abdominal infection (cIAI), or complicated urinary tract infection (cUTI). Patients were mMITT-eligible if pathogens were imipenem-NS (but CST- and IMI/REL-susceptible) based on central laboratory minimum inhibitory concentration (MIC). SmMITT comprised mMITT plus all patients who met inclusion criteria only based on local laboratory MIC. Results The SmMITT population (n = 41 [28 IMI/REL; 13 IMI+CST]) comprised 31 from mMITT plus 10 based on local MIC; 12/41 (29%) had HABP/VABP, 8/41 (20%) cIAI, and 21/41 (51%) cUTI. The majority of differences in central vs. local MIC were 1–2 dilutions; similar numbers of patients were excluded from mMITT due to imipenem susceptibility (n = 5) or IMI/REL-NS (n = 4); 1 patient was CST-NS. Baseline characteristics, including infecting pathogens, were comparable in SmMITT and mMITT (SmMITT: 68% male; 46% ?65 y; 24% APACHE II score >15; 22% creatinine clearance <60 mL/minute). Rates of efficacy outcomes (overall response, day 28 clinical response, day 28 mortality) were comparable between populations, except that response rates in patients with cIAI were higher in SmMITT (table). Conclusion Consistency of results was demonstrated across two analysis populations in a trial of resistant pathogens. This analysis provides results supportive of expected future clinical use of IMI/REL when treatment decisions will be made based on local laboratory results. Disclosures K. Kaye, Merck & Co., Inc.: Consultant and Research Contractor, Research grant. Melinta, Achaogen, Allergan: Consultant, Consulting fee. T. File, Bio Merieux, Curetis, Melinta, Merck, MotifBio, Nabriva, Paratek, Pfizer: Consultant, Consulting fee. H. W. Boucher, Merck & Co., Inc.: Scientific Advisor, Consulting fee. M. Brown, Merck & Co., Inc.: Employee, Salary. A. Aggrey, Merck & Co., Inc.: Employee, Salary. I. Khan, Merck & Co., Inc.: Employee, Salary. H. K. Joeng, Merck & Co., Inc.: Employee, Salary. R. Tipping, Merck & Co., Inc.: Employee, Salary. J. Du, Merck & Co., Inc.: Employee, Salary. K. Young, Merck & Co., Inc.: Employee, Salary and Stock options. J. Butterton, Merck & Co., Inc.: Employee, Salary and Stock. N. A. Kartsonis, Merck & Co., Inc.: Employee, Salary and Stocks. A. Paschke, Merck & Co., Inc.: Employee and Shareholder, Salary.

Project description:BACKGROUND:The ?-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.

Project description:BackgroundImipenem combined with the β-lactamase inhibitor relebactam has broad antibacterial activity, including against carbapenem-resistant gram-negative pathogens. We evaluated efficacy and safety of imipenem/cilastatin/relebactam in treating hospital-acquired/ventilator-associated bacterial pneumonia (HABP/VABP).MethodsThis was a randomized, controlled, double-blind phase 3 trial. Adults with HABP/VABP were randomized 1:1 to imipenem/cilastatin/relebactam 500 mg/500 mg/250 mg or piperacillin/tazobactam 4 g/500 mg, intravenously every 6 hours for 7-14 days. The primary endpoint was day 28 all-cause mortality in the modified intent-to-treat (MITT) population (patients who received study therapy, excluding those with only gram-positive cocci at baseline). The key secondary endpoint was clinical response 7-14 days after completing therapy in the MITT population.ResultsOf 537 randomized patients (from 113 hospitals in 27 countries), the MITT population comprised 264 imipenem/cilastatin/relebactam and 267 piperacillin/tazobactam patients; 48.6% had ventilated HABP/VABP, 47.5% APACHE II score ≥15, 24.7% moderate/severe renal impairment, 42.9% were ≥65 years old, and 66.1% were in the intensive care unit. The most common baseline pathogens were Klebsiella pneumoniae (25.6%) and Pseudomonas aeruginosa (18.9%). Imipenem/cilastatin/relebactam was noninferior (P < .001) to piperacillin/tazobactam for both endpoints: day 28 all-cause mortality was 15.9% with imipenem/cilastatin/relebactam and 21.3% with piperacillin/tazobactam (difference, -5.3% [95% confidence interval {CI}, -11.9% to 1.2%]), and favorable clinical response at early follow-up was 61.0% and 55.8%, respectively (difference, 5.0% [95% CI, -3.2% to 13.2%]). Serious adverse events (AEs) occurred in 26.7% of imipenem/cilastatin/relebactam and 32.0% of piperacillin/tazobactam patients; AEs leading to treatment discontinuation in 5.6% and 8.2%, respectively; and drug-related AEs (none fatal) in 11.7% and 9.7%, respectively.ConclusionsImipenem/cilastatin/relebactam is an appropriate treatment option for gram-negative HABP/VABP, including in critically ill, high-risk patients.Clinical trials registrationNCT02493764.

Project description:Relebactam is a novel class A/C β-lactamase inhibitor that restores imipenem in vitro activity against multidrug-resistant and carbapenem-nonsusceptible Pseudomonas aeruginosa Time-kill analyses were performed to evaluate the potential role of imipenem-relebactam in combination with amikacin or colistin against P. aeruginosa Ten clinical P. aeruginosa isolates (9 imipenem nonsusceptible) with imipenem-relebactam MICs ranging from 1/4 to 8/4 μg/ml were included. The isolates had varied susceptibilities to imipenem (1 to 32 μg/ml), amikacin (4 to 128 μg/ml), and colistin (0.5 to 1 μg/ml). Duplicate 24-h time-kill studies were conducted using the average steady-state concentrations (Cssavg) observed after the administration of imipenem-relebactam at 500 mg/250 mg every 6 hours (q6h) alone and in combination with the Cssavg of 25 mg/kg of body weight/day amikacin and 360 mg/day colistin in humans. Imipenem-relebactam alone resulted in 24-h bacterial densities of -2.93 ± 0.38, -1.67 ± 0.29, +0.38 ± 0.96, and +0.15 ± 0.65 log10 CFU/ml at imipenem-relebactam MICs of 1/4, 2/4, 4/4, and 8/4 μg/ml, respectively. No synergy was demonstrated against the single imipenem-susceptible isolate. Against the imipenem-nonsusceptible isolates (n = 9), imipenem-relebactam combined with amikacin resulted in synergy (-2.61 ± 1.50 log10 CFU/ml) against all amikacin-susceptible isolates and in two of three amikacin-intermediate (i.e., MIC, 32 μg/ml) isolates (-2.06 ± 0.19 log10 CFU/ml). Synergy with amikacin was not observed when the amikacin MIC was >32 μg/ml. Imipenem-relebactam combined with colistin demonstrated synergy in eight out of the nine imipenem-resistant isolates (-3.17 ± 1.00 log10 CFU/ml). Against these 10 P. aeruginosa isolates, imipenem-relebactam combined with either amikacin or colistin resulted in synergistic activity against the majority of strains. Further studies evaluating combination therapy with imipenem-relebactam are warranted.

Dataset Information

Comparison of Treatment Outcomes between Analysis Populations in the RESTORE-IMI 1 Phase 3 Trial of Imipenem-Cilastatin-Relebactam versus Colistin plus Imipenem-Cilastatin in Patients with Imipenem-Nonsusceptible Bacterial Infections.

Publications

Comparison of Treatment Outcomes between Analysis Populations in the RESTORE-IMI 1 Phase 3 Trial of Imipenem-Cilastatin-Relebactam versus Colistin plus Imipenem-Cilastatin in Patients with Imipenem-Nonsusceptible Bacterial Infections.

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