Evaluation of Safety, Pharmacokinetics and Efficacy of Ceftazidime and Avibactam (CAZ-AVI ) Compared With Cefepime in Children From 3 Months to Less Than 18 Years of Age With Complicated Urinary Tract Infections (cUTIs)

This study will assess the safety, tolerability and efficacy of ceftazidime and avibactam (CAZ-AVI )versus cefepime in children from 3 months to less than 18 years old with complicated urinary tract infections.

This study will be a single-blind, randomised, multi-centre, active controlled trial. Patients aged from 3 months to less than 18 years with complicated urinary tract infections (cUTIs) will be randomised to 1 of 2 treatment groups (3:1 ratio): Ceftazidime and avibactam (CAZ AVI )or cefepime. Randomisation will be stratified by age cohort.

Patients will receive intravenous (IV) treatment for a minimum of 72 hours (3 full days, ie, 9 doses if given 3 times daily, or 6 doses if given twice daily) before having the option to switch to an oral therapy . The decision to switch to oral therapy is entirely at the Investigator's discretion, if the patient has good or sufficient clinical response, and the patient is tolerating oral fluids or food.

Patients will be assessed for safety and efficacy throughout the study, and blood samples will be taken for pharmacokinetic assessment. The duration of each patient's participation in the study will be a minimum of 27 days to a maximum of 50 days after start of study treatment including (intravenous treatment or oral switch therapy) 7 to 14 days of active treatment. The late follow-up visit (LFU) is to be performed 20 to 36 days after the last dose of any treatment.

The assessments at the test of cure (TOC) visit should be performed in person 8 to 15 days after last dose of any study drug Maximum duration of study drug or oral switch therapy is up to Day 14.

Eligibility Criteria:
Inclusion Criteria:

1. Must be ≥3 calendar months to \<18 years of age. Patients aged ≥3 calendar months to \<1 year must have been born at term (defined as gestational age ≥37 weeks).
2. Written informed consent from parent(s) or other legally acceptable representative(s), and informed assent from patient (if age appropriate according to local regulations)
3. If female and has reached menarche, or has reached Tanner stage 3 development (even if not having reached menarche) (refer to Appendix E for further details on Tanner staging), the patient is authorised to participate in this clinical study if the following criteria are met:

   At screening:

   (i) (a) Patient reports sexual abstinence for the prior 3 months or reports use of at least 1 of the acceptable methods of contraception, including an intrauterine device (with copper banded coil), levonorgestrel intrauterine system (eg, Mirena®), or regular medroxyprogesterone injections (Depo-Provera®); or (b) Patient agrees to initiate sexual abstinence from the time of screening until 7 days after end of treatment with study drug; and (ii) Patient is advised to avoid conception from the time of screening until 7 days after receipt of study drug and agrees not to attempt pregnancy from the time of screening until 7 days after end of treatment with study drug; and (iii) Patient is provided guidelines regarding continuation of abstinence, initiation of abstinence, or about allowed contraception; and (iv) Patient has a negative serum β-human chorionic gonadotropin (β-hCG) test just prior to study entry. Since serum tests may miss an early pregnancy, relevant menstrual history and sexual history, including methods of contraception, should be considered. Note: if the result of the serum β-hCG test cannot be obtained prior to dosing of investigational product, a patient may be enrolled on the basis of a negative urine pregnancy test, though a serum β-hCG test result must still be obtained.
4. Patient has a clinically suspected and/or bacteriologically documented cUTI or acute pyelonephritis judged by the Investigator to be serious and requires the patient to be hospitalised for treatment with intravenous (IV) therapy
5. Patient has pyuria:

   Cohorts 1 to 3 as determined by a midstream clean catch or clean urethral catheterisation urine specimen with ≥10 white blood cells (WBCs) per high power field on standard examination of urine sediment or ≥10 WBCs/mm3 in unspun urine Cohort 4a and 4b as determined by a midstream clean catch or clean urethral catheterisation urine specimen or urine specimen obtained using urine collection pads(or supra-pubic collection if standard procedure in the assigned sites) ≥5 WBCs per high-power field on standard examination of urine sediment or ≥5 WBCs/mm3 in unspun urine
6. Patient has a positive urine culture: 1 midstream clean catch or clean urethral catheterisation urine specimen taken within 48 hours of randomisation containing ≥105 colony-forming units (CFU)/mL of a recognised uropathogen known to be susceptible to the IV study therapy (CAZ-AVI and cefepime) Note: If patients meet all of entry criteria except for positive urine culture as outlined above, the patients may be enrolled before urine culture results are available if the results are likely (based on urinalysis and clinical findings) to be positive and study drugs are considered appropriate empiric therapy. If a patient urine culture is negative after 24 or 48 hours of treatment but the patient is improving, the Investigator can keep the patient on treatment. If the urine culture is negative and the patient is not improving, study treatment will be stopped, and the patient will be followed for the rest of the study including undergoing all safety assessments until late follow up (LFU).
7. Demonstrates either acute pyelonephritis or complicated lower UTI as defined by the following criteria:

   1. Qualifying criteria: patients must have at least 1 of the following signs/symptoms (signs/symptoms must have onset or have worsened within 7 days of enrolment) in addition to pyuria:

      Dysuria (including perceived dysuria as referred by parent/caregiver) Urgency Frequency Abdominal pain Fever defined as oral temperature \>38.5°C (or equivalent by other methods) with or without patient symptoms of rigor, chills, warmth Nausea Vomiting Irritability Loss of appetite Flank pain
   2. Or patients considered to have complicated UTI as indicated by 2 of the previous qualifying signs/symptoms in (a) plus at least 1 complicating factor from the following:

Recurrent UTI (2 or more within 12 months period) Obstructive uropathy that is scheduled to be surgically relieved during IV study therapy and before the EOT Functional or anatomical abnormality of the urogenital tract, including anatomic malformations or neurogenic bladder Vesicoureteral reflux Use of intermittent bladder catheterisation or presence of an indwelling bladder catheter for \>48 hours prior to the diagnosis of cUTI Urogenital procedure (eg, cystoscopy or urogenital surgery) within the 7 days prior to study entry

Exclusion Criteria:

1. Involvement in the planning and/or conduct of the study (applies to both AstraZeneca staff and/or staff at the study site)
2. Previous enrolment or randomisation in the present study
3. Participation in another clinical study with an investigational product (IP) during the last 30 days before the first dose of IV study drug or have previously participated in the current study or in another study of CAZ-AVI (in which an active agent was received)
4. History of hypersensitivity reactions to carbapenems, cephalosporins, penicillins or other β-lactam antibiotics
5. Concurrent infection, including, but not limited to, central nervous system infection requiring systemic antibiotics in addition to the IV study drug therapy at the time of randomisation
6. Receipt of more than 24 hours of any systemic antibiotics after culture and before study drug therapy
7. Receipt of systemic antibiotics within 24 hours before obtaining the study qualifying pre-treatment baseline urine sample and before study drug therapy
8. The child is suspected or documented to have an infection caused by organisms resistant to the prophylactic antibiotics
9. A permanent indwelling bladder catheter or instrumentation including nephrostomy or current urinary catheter that will not be removed or anticipation of urinary catheter placement that will not be removed during the course of IV study drug therapy administration
10. Patient has suspected or known complete obstruction of any portion of the urinary tract, perinephric abscess, or ileal loops
11. Patient has had trauma to the pelvis or urinary tract
12. Patient has undergone renal transplantation
13. Patient has a condition or history of any illness that, in the opinion of the Investigator, would make the patient unsuitable for the study (eg, may confound the results of the study or pose additional risk in administering the study therapy to the patient)
14. Patient is considered unlikely to survive the 6 to 8 week study period or have a rapidly progressive illness, including septic shock that is associated with a high risk of mortality
15. At the time of randomisation, patient is known to have a cUTI caused by pathogens resistant to the antimicrobials planned to be used in the study
16. Presence of any of the following clinically significant laboratory abnormalities:

    1. Haematocrit \<25% or haemoglobin \<8 g/dL (\<80 g/L, \<4.9 mmol/L)
    2. Serum alanine aminotransferase (ALT) or aspartate aminotransferase (AST) \>3×the age-specific upper limit of normal (ULN), or total bilirubin \>2×ULN (except known Gilbert's disease) For a) to b): unless if these values are acute and directly related to the infectious process being treated.
17. Creatinine clearance \<30 mL/min/1.73 m2 calculated using the child's measured height (length) and serum creatinine within the updated "bedside" Schwartz formula (Schwartz et al 2009):

    CrCl (mL/min/1.73m2)=0.413×height (length) (cm)/serum creatinine (mg/dL)
18. History of seizures, excluding well-documented febrile seizure of childhood
19. If female, currently pregnant or breast feeding