Pentaglobin in CRE and PA Neutropenic Infections

The study will enroll adult patients suffering from acute leukemia candidate to intensive chemotherapy or patients with hematological cancers candidate to allogeneic transplant with a documented colonization or previous bloodstream infection sustained by Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa.

Primary objective: to demonstrate that the early addition of Pentaglobin to the best available antimicrobial therapy is able to reduce mortality and improve survival in neutropenic febrile acute leukemia or allo- Hematopoietic stem cell transplantation (HSCT) patients colonized by carbapenem-resistant Enterobacteriaceae or by any Pseudomonas aeruginosa.

Secondary Objectives: to evaluate the overall impact of Pentaglobin administration in the study population concerning infectious complications and treatment-related mortality.

This study will have two co-primary endpoints:

To demonstrate a 50% reduction in 30-day mortality for carriers developing a pre-engraftment bloodstream infection sustained by carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa (earlier primary endpoint).

To increase the Overall Survival (OS) at 4 months from the start of intensive treatment in all carriers of CRE or PA compared to historical controls (later primary endpoint)

Secondary endpoint are:

OS in carriers not developing a bloodstream infection sustained by carbapenem-resistant Enterobacteriaceae (CRE) or Pseudomonas aeruginosa (PA) at 4 months from the start of intensive chemotherapy or transplant Days of fever > 38.3°C within 4 months from the start of start of intensive chemotherapy or transplant Days of hospitalization within 4 months from the start of intensive chemotherapy or transplant Days of i.v. antimicrobials within 4 months from the start of intensive chemotherapy or transplant Non-relapse mortality (NRM) at 4 months from the start of intensive chemotherapy or transplant Patients will be treated according to the standard procedures, which will be decided by each Center according to local policies (e.g. chemotherapy cycles for acute leukemia, choice of conditioning regimen for allo- Hematopoietic stem cell transplantation and graft-versus-host- disease prophylaxis, anti-microbial prophylaxis).

Pre-treatment microbiological screening Before the initiation of intensive chemotherapy (within 2 weeks) patients will be screened by rectal and pharyngeal swabbing for multidrug-resistant Gram-negative bacilli, as part of routine clinical practice.

If the rectal and/or pharyngeal swabs reveal the presence of Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa, the patient will be considered eligible for the study.

Patients with a previous documented infection (within 3 months) caused by Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa are also considered eligible for the study regardless of the result of the rectal/pharyngeal swabs.

Treatment and management of febrile neutropenia in Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa carriers Antimicrobial treatment active against the multidrug-resistant strain should be started in case of neutropenic fever, defined as a single oral temperature of ≥38.3°C or a temperature of ≥38.0°C sustained over a one-hour period.

At the onset of neutropenic fever and before the initiation of antimicrobial therapy at least 2 sets of blood cultures (2 bottles from a peripheral vein and 2 bottles from central venous catheter) should be performed.

Patients should receive the best available first-line therapy, usually a combination therapy, based on the in vitro susceptibility results of the pre-treatment screening swab in combination to Pentaglobin 5ml/kg over a 12h i.v. infusion for 3 consecutive days. Empirical treatment should be subsequently streamlined according to microbiological results (both positive and negative) Pentaglobin should be started within 12h from the onset of fever, regardless of the presence of hemodynamic stability.

Septic shock should be diagnosed and managed according to standard procedure The duration of the antimicrobial therapy or subsequent lines of therapy will be decided by local investigators according to clinical judgment. Cycles of Pentaglobin can be repeated according to clinician judgment (usually at least 1 week).

In this study two co-primary endpoints will be evaluated: the 30-day mortality rate for carriers developing a pre-engraftment bloodstream infection sustained by Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa and the Overall Survival at 4 months from the start of intensive treatment in pre-treatment carriers.

In order to address the multiplicity issue, the Bonferroni method to adjust the significance level will be applied as follows:

• the early endpoint (i.e. the "30-day mortality for carriers developing a pre-engraftment bloodstream infection sustained by CRE or PA") will be tested at the 3.0% significance level using the Simon (minimax) phase II study design;
• the late endpoint (i.e. the "OS at 4 months from the start of intensive treatment in pre-treatment carriers") will be tested at the 2.0% significance level.

Adaptive study design

Early primary endpoint:

30-day mortality rate for carriers developing a pre-engraftment bloodstream infection sustained by Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa.

The test was planned to determine whether it will be possible to obtain a consistent rate of reduction in 30-day mortality for carriers developing a pre-engraftment bloodstream infection sustained by CRE or PA. In the proposal, to reject the null hypothesis that p<=0.60 (mortality rate: 0.40) vs. the alternative hypothesis that p>=0.80 (mortality rate: 0.20) with Type I error probability (α) equal to 0.03 and 80% power (1-β), a maximum of 40 evaluable patients has to be accrued.

In the first stage of the study, 31 evaluable patients will be enrolled and the trial will be terminated if 9 or more patients died by day +30; otherwise, 9 further evaluable patients will be enrolled in the second stage.

If the total number of patients died will be less than or equal to 11, the combination therapy will not be recommended for further studies.

If the total number of patients alive at day +30 is at least 30, the treatment will be deemed worthy of further investigations.

Considering that approximately 33% of enrolled patients will be "carriers developing a pre-engraftment bloodstream infection sustained by CRE or PA", a total of 120 patients will be needed to be enrolled.

So, considering the study design, an interim analysis is planned after 31 carriers developing a pre-engraftment bloodstream infection sustained by CRE or PA.

Late primary endpoint:

Overall Survival at 4 months from the start of intensive treatment in pre-treatment Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa carriers.

The later endpoint is the Overall Survival at 4 months. This sample size was calculated using the "Sample size tables for exact single-stage phase II design" (A'Hern RP, Statistics in Medicine 2001). Considering an expected Overall Survival at 4 months of 70% from the start of intensive treatment in pre-treatment carriers, the number of patients required to evaluate an increase on the Overall Survival from 50% (P0) to 70% (P1) with 90% power at the 2.0% significance level (one side) is 68.

So, the total number of patients to be enrolled in this study is 120, including the 68 patients needed for the later endpoint. Calculations were made using PASS software.

The Data Safety Monitoring Board will make one monitoring at 31 evaluable patients (in concomitant with the interim analysis) to ensure the safety of patients enrolled in to the study.

The end of enrollment will end based on the ad interim analysis results according to the adaptive model of the study.

Enrollment may then terminate after the interim analysis provided after recording 31 bacteremia in 31 patients with CRE or PA or when the 120th patient will be enrolled.

Each patient enrolled will have a minimum follow-up period of 4 months from transplant or start chemotherapy.

Each patient enrolled developing bacteremia sustained by Carbapenem-resistant Enterobacteriaceae or Pseudomonas aeruginosa will have a 30-day follow-up from initiation of treatment with Pentaglobin.

It is planned to complete the total enrollment (120 patients) in 2 years starting from the first patient enrolled.