Ceftolozane-Tazobactam for Directed Treatment of Pseudomonas Aeruginosa Bacteremia and Pneumonia in Patients With Hematological Malignancies and Hematopoietic Stem Cell Transplantation

January 16, 2026 updated by: Weill Medical College of Cornell University

A Pilot Study of Ceftolozane-Tazobactam in Conjunction With Rapid Molecular Diagnosis for Directed Treatment of Pseudomonas Aeruginosa Bacteremia and Pneumonia in Patients With Hematological Malignancies and Hematopoietic Stem Cell Transplantation

The goal of this clinical trial is to learn whether the antibiotic ceftolozane-tazobactam works to treat serious Pseudomonas aeruginosa infections in people with blood cancers or who received a stem cell transplant. The main question it aims to answer is whether participants reach clinical success 30 days after the infection is first found. Clinical success means the person is alive, their infection symptoms are improving, and the infection has not returned.

Participants will receive ceftolozane-tazobactam through a vein every 8 hours for 10 to 14 days. Treatment may continue for up to 21 days if the infection is not improving or keeps coming back. The infection is diagnosed using the hospital's standard rapid molecular tests, which help confirm Pseudomonas aeruginosa quickly so treatment can begin right away.

Researchers will follow participants during their hospital stay and check on them around 30 and 60 days to see how well the treatment worked. The study will also look at how long it takes for the infection to clear, how long participants stay in the hospital or intensive care unit, and whether the bacteria become resistant to antibiotics.

In addition to the prospective ceftolozane-tazobactam group, the study includes a historical control group made up of patients with similar infections who were treated in the past with standard anti-pseudomonal antibiotics (such as cefepime, ceftazidime, piperacillin-tazobactam, or meropenem). Data from these historical controls are collected by chart review and analyzed alongside the prospective group to compare outcomes. Historical controls do not receive study-directed treatment and are not actively enrolled under this protocol.

Study Overview

Status

Terminated

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

17

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • New York
      • New York, New York, United States, 10065
        • Weill Cornell Medicine

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (Adult, Older Adult)

Accepts Healthy Volunteers

No

Description

Eligibility Criteria

Inclusion Criteria

  • Presence of a hematologic malignancy or a history of hematopoietic stem cell transplantation
  • Identification of Pseudomonas aeruginosa by rapid molecular diagnostic testing from a positive blood culture or from a respiratory sample in the setting of radiologically documented pneumonia with compatible clinical symptoms
  • Age 18 years or older
  • Ability of the participant or legally authorized representative to provide informed consent

Exclusion Criteria

  • Receipt of more than 72 hours of non-study anti pseudomonal therapy for the infection being treated
  • Known anaphylactic hypersensitivity or allergic reaction to cephalosporins
  • History of a Pseudomonas aeruginosa isolate with a ceftolozane or tazobactam MIC greater than 4 micrograms per milliliter
  • Polymicrobial aerobic Gram negative infection, as determined by the infectious diseases research team
  • Hemodialysis, continuous renal replacement therapy, or creatinine clearance less than 15 milliliters per minute
  • Expected mortality within 48 hours of screening

Eligibility Criteria for Historical Controls

Inclusion Criteria

  • Presence of a hematologic malignancy or a history of hematopoietic stem cell transplantation
  • Identification of Pseudomonas aeruginosa associated with bacteremia and or pneumonia
  • Age 18 years or older
  • Survival greater than 48 hours after initiation of anti pseudomonal therapy for Pseudomonas aeruginosa bacteremia and or pneumonia

Exclusion Criteria

  • Known anaphylactic hypersensitivity or allergic reaction to cephalosporins
  • History of a Pseudomonas aeruginosa isolate with a ceftolozane or tazobactam MIC greater than 4 micrograms per milliliter
  • Polymicrobial aerobic Gram negative infection, as determined by the infectious diseases research team
  • Hemodialysis, continuous renal replacement therapy, or creatinine clearance less than 15 milliliters per minute

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Ceftolozane-Tazobactam (Prospective Treatment Arm)
Participants prospectively enrolled in the study received ceftolozane-tazobactam intravenously every 8 hours for approximately 10 to 14 days, with treatment extended up to 21 days if infection persisted or recurred. Outcomes for this arm were assessed according to the protocol's primary and secondary endpoints.
Drug: Ceftolozane / Tazobactam Injection
Zerbaxa (ceftolozane/tazobactam) for injection is supplied as a white to yellow sterile powder for reconstitution in single-use vials; each vial contains 1 g ceftolozane (equivalent to 1.147 g of ceftolozane sulfate) and 0.5 g tazobactam (equivalent to 0.537 g of tazobactam sodium).
No Intervention: Historical Control (Standard of Care Prior to Study)
This arm consists of historical control patients with documented Pseudomonas aeruginosa bacteremia and/or pneumonia who received standard-of-care antimicrobial therapy prior to initiation of this study. These patients were included retrospectively for comparative analyses of selected primary and secondary endpoints. No study interventions were administered to this arm.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Clinical Success at Day 30
Time Frame: 30 days after collection of the index culture
Clinical success 30 days after collection of the index culture. Clinical success is defined as meeting all of the following criteria at that time point: survival; resolution or near resolution of baseline clinical manifestations, including fever, hypoxia, and signs or symptoms of sepsis; and absence of recurrent infection due to Pseudomonas aeruginosa or persistent infection despite more than 7 days of anti-pseudomonal therapy.
30 days after collection of the index culture

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Survival at Day 30
Time Frame: 30 days after initiation of anti-pseudomonal therapy for the index infection
Survival status 30 days after initiation of anti-pseudomonal therapy for the index infection, assessed by chart review or phone contact.
30 days after initiation of anti-pseudomonal therapy for the index infection
Survival at Day 60
Time Frame: 60 days after initiation of anti-pseudomonal therapy for the index infection
Survival status 60 days after initiation of anti-pseudomonal therapy for the index infection, assessed by chart review or phone contact.
60 days after initiation of anti-pseudomonal therapy for the index infection
Time to Resolution of Bacteremia
Time Frame: From index culture collection up to 60 days
Time (days) from the index positive blood culture for Pseudomonas aeruginosa to bacteremia resolution. Resolution was defined as the date of the first of two consecutive negative blood cultures obtained after the index culture. Participants without follow-up blood cultures were excluded from this analysis.
From index culture collection up to 60 days
Length of Hospital Stay
Time Frame: From index culture collection through discharge from the hospital admission for the index infection (up to 60 days)
Total number of days hospitalized for the admission during which the index Pseudomonas aeruginosa infection is treated, measured beginning on the date of index culture collection and obtained from the Hospitalization Status Assessment.
From index culture collection through discharge from the hospital admission for the index infection (up to 60 days)
Emergence of Ceftolozane-tazobactam Resistant Isolates
Time Frame: From index culture collection up to 60 days
Occurrence of Pseudomonas aeruginosa isolates that newly demonstrate resistance to ceftolozane-tazobactam on antimicrobial susceptibility testing after initiation of therapy for the index infection.
From index culture collection up to 60 days
Time to Appropriate Therapy
Time Frame: From index culture collection up to 60 days
Time (in hours) from index culture collection for the index Pseudomonas aeruginosa infection to initiation of an anti-pseudomonal agent deemed appropriate based on antimicrobial susceptibility results.
From index culture collection up to 60 days
Resolution of Baseline Clinical Manifestations
Time Frame: 30 days after collection of the index culture
Resolution or near resolution of baseline fever, hypoxia, or signs and symptoms of sepsis related to the index infection at 30 days after index culture collection, as assessed by physical examination findings and clinical documentation.
30 days after collection of the index culture
Modifications to Initial Antimicrobial Therapy
Time Frame: From initiation of study ceftolozane-tazobactam therapy through end of study-directed anti-pseudomonal treatment (up to 21 days)
Number of participants with any modification to the initial study-directed anti-pseudomonal regimen for the index infection, defined as either (1) discontinuation of ceftolozane-tazobactam with switch to another anti-pseudomonal agent or (2) addition of another anti-pseudomonal antibiotic during the treatment course. Outpatient levofloxacin was not considered a modification.
From initiation of study ceftolozane-tazobactam therapy through end of study-directed anti-pseudomonal treatment (up to 21 days)
Emergence of Other Bacteria During Therapy
Time Frame: From initiation of study ceftolozane-tazobactam therapy through end of ceftolozane-tazobactam treatment (up to 21 days)
Identification of new bacterial pathogens identified in blood cultures during study-directed ceftolozane-tazobactam treatment for the index infection.
From initiation of study ceftolozane-tazobactam therapy through end of ceftolozane-tazobactam treatment (up to 21 days)
Number of Days on Ventilator
Time Frame: From index culture collection through discharge from the hospital admission for the index infection (up to 60 days)
Total number of days requiring invasive mechanical ventilation during the index admission, measured beginning on the date of index culture collection and abstracted from the medical record.
From index culture collection through discharge from the hospital admission for the index infection (up to 60 days)
ICU Length of Stay
Time Frame: From index culture collection through discharge from the hospital admission for the index infection (up to 60 days)
Total number of days spent in an intensive care unit during the index admission, measured beginning on the date of index culture collection and obtained from the Hospitalization Status Assessment.
From index culture collection through discharge from the hospital admission for the index infection (up to 60 days)

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Weill Medical College of Cornell University

Collaborators

Merck Sharp & Dohme LLC

Investigators

  • Principal Investigator: Markus Plate, MD, Weill Medical College of Cornell University

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

January 10, 2023

Primary Completion (Actual)

March 16, 2025

Study Completion (Actual)

March 16, 2025

Study Registration Dates

First Submitted

December 4, 2020

First Submitted That Met QC Criteria

December 11, 2020

First Posted (Actual)

December 17, 2020

Study Record Updates

Last Update Posted (Actual)

January 21, 2026

Last Update Submitted That Met QC Criteria

January 16, 2026

Last Verified

January 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 19-11021048

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

Yes

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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