Aztreonam-avibactam effective against MDR pathogens in REVISIT trial
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Key takeaways:
- Aztreonam-avibactam was well tolerated and comparable in efficacy to meropenem.
- Pfizer plans to start the regulatory process of getting ATM-AVI approved later this year.
BOSTON — Aztreonam-avibactam was shown to be effective in the treatment of hospitalized adults who were critically ill with multidrug-resistant, gram-negative bacterial infections, according to the results of the phase 3 REVISIT trial.
The findings, which were presented at IDWeek, suggested Pfizer’s novel antibiotic combination was well tolerated and comparable in efficacy to meropenem — potentially offering a new treatment option against gram-negative infections, including those caused by metallo-beta-lactamase-producing, multidrug-resistant (MDR) pathogens.
Yehuda Carmeli, MD, professor of medicine and head of the Israeli National Center for Antibiotic Resistance in Tel Aviv, and colleagues conducted the study in adults who were hospitalized with complicated intra-abdominal infections (cIAI) and hospital-acquired or ventilator-associated pneumonia (HAP/VAP) caused by MDR bacteria. According to the researchers, 422 participants were randomly assigned in a 2:1 ratio to receive either aztreonam-avibactam (ATM-AVI) with or without metronidazole, or meropenem with or without colistin. Those with cIAI were treated for 5 to 14 weeks, and those with HAP/VAP were treated for 7 to 14 weeks.
The study’s two primary efficacy endpoints were clinical cure at the test-of-cure (TOC) visit in the intent-to-treat (ITT) population and among a clinically evaluable subset of patients. Secondary endpoints included microbiological responses at TOC, 28-day mortality and the safety of the drug combination.
According to a press release from Pfizer earlier this year, the cure rate in the ITT group among patients with cIAI who received the study drug combination was 76.4% (95% CI, 70.3%-81.8%) vs. 74% (95% CI, 65%-81.7%) among those who received meropenem — a difference of 2.4% (95% CI, –12.5% to 19.1%). In the subset of patients with cIAI who were clinically evaluable, the cure rates were 85.1% (95% CI, 79.2%-89.9%) with ATM-AVI and 79.5% (95% CI, 69.9%-87.1%) with meropenem.
The Pfizer press release also showed that among patients in the ITT group with HAP/VAP, the cure rates were 45.9% (95% CI, 34.9%-57.3%) with ATM-AVI vs. 41.7% (95% CI, 26.7%-57.9%) with meropenem, with a treatment difference of 4.3% (95% CI, –25.6% to 32.2%). Among clinically evaluable patients with HAP/VAP, cure rates were 46.7% (95%CI, 32.7%-61.1%) vs. 54.5% (95% CI, 34.3%-73.7%).
The researchers reported at IDWeek that the favorable microbiological response rates at TOC in the ITT subgroup were 75.7% with ATM-AVI and 73.9% with meropenem.
Additionally, 28-day mortality rates were 1.9% in the ATM-AVI group and 2.9% in the meropenem group.
The researchers said ATM-AVI was well tolerated, and they reported no serious treatment-related adverse events. Pfizer said in the release that the combination had a similar safety profile to aztreonam alone.
Pfizer said it plans to use these findings — as well as results from a previous study called ASSEMBLE — to start the regulatory process of getting ATM-AVI approved later this year.
“These clinical findings show that ATM-AVI, if approved, could help provide coverage against gram-negative bacteria without compromising on efficacy or safety,” Carmeli said in the release. “These data are particularly promising given the complexities of managing cIAI and HAP/VAP infections in these hospitalized, critically ill patients, and the challenges of real-world patient recruitment within this population.”
References:
- Carmeli Y, et al. Abstract 2893 A. Presented at: IDWeek; Oct. 11-15, 2023; Boston.
- Phase 3 studies of Pfizer’s novel antibiotic combination offer new treatment hope for patients with multidrug-resistant infections and limited treatment options. https://www.pfizer.com/news/press-release/press-release-detail/phase-3-studies-pfizers-novel-antibiotic-combination-offer. Published June 1, 2023. Accessed Oct. 11, 2023.
Perspective
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ATM-AVI met its noninferiority endpoint and appears to be a safe option for patients. I think the lack of highly resistant pathogens (small numbers) in the study might be a limitation, as clinicians will be looking to use ATM-AVI for the treatment of MDR or extensively drug-resistant pathogens. However, the in-vitro data and pre-clinical data are encouraging for ATM-AVI against resistant gram-negative pathogens.
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Carmeli Y, et al. Abstract 2893 A. Presented at: IDWeek; Oct. 11-15, 2023; Boston.
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