A Study of Intravenous Zanamivir in the Treatment of Hospitalized Patients With Influenza Infection

An AE is defined as any untoward medical occurrence in a participant, temporally associated with the use of a medicinal product, whether or not considered related to the medicinal product. An SAE is defined as any untoward medical occurrence that, at any dose, results in death, is life-threatening, requires hospitalization or prolongation of existing hospitalization, results in disability/incapacity, or is a congenital anomaly/birth defect, may jeopardize the participant or may require medical or surgical intervention to prevent one of the other outcomes listed in this definition, associated with liver injury and impaired liver function defined as alanine aminotransferase >=3 x upper limit of normal (ULN), and total bilirubin >=2 x ULN or international normalised ratio >1.5. The grading of AEs and SAE's for 3/4 (3= severe, 4= potentially life threatening ) and its classification as potentially drug-related was done based on the investigator's judgment.

The reference ranges for clinical chemistry parameters were ALT 5 to 45 international units per litre [IU/L]), ALP 100 to 325 IU/L, creatine kinase 60 to 270 IU/L and AST 10 to 40 IU/L. The baseline assessments were referred to assessments at Day 1. Assessments were done at Day 1, 3 and 5.

The reference ranges for clinical chemistry parameters were creatinine 41.548 - 69.836 micromole per litre (µmol/L), direct bilirubin 0 to 5.13 µmol/L and total bilirubin 3.42 to 20.52 µmol/L. The baseline assessments were referred to assessments at Day 1. Assessments were done at Day 1, 3 and 5.

The reference ranges for clinical chemistry parameters were calcium 2.0958 to 2.5948 millimole per litre (mmol/L), carbon dioxide content/ bicarbonate 19.2 to 27.1 mmol/L, chloride 98 to 108 mmol/L, magnesium 0.7809 to 1.0275 mmol/L, potassium 3.5 to 5 mmol/L, sodium 137 to 147 mmol/L and urea/BUN 2.856 to 8.211 mmol/L. The baseline assessments were referred to assessments at Day 1. Assessments were done at Day 1, 3 and 5.

The reference ranges for clinical chemistry parameters were albumin 38 to 53 grams per liter (g/L) and total protein 67 to 83 g/L. The baseline assessments were referred to assessments at Day 1. Assessments were done at Day 1, 3 and 5.

The reference ranges for hematology parameters were basophils 0 to 2 percentage (%), eosinophils 0 to 8%, lymphocytes 18 to 49%, monocytes 2 to 10%, total neutrophils 40 to 75%, platelet count 140 to 340 giga cells per liter (GI/L), WBC count 3.3 to 9 GI/L, hemoglobin 135 to 175 g/L and haematocrit 0.397 to 0.524 ratio. The baseline assessments were referred to assessments at Day 1. Assessments were done at Day 1, 3, and 5.

Albumin and total protein were measured at Baseline , Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

ALT, ALP, creatine kinase and AST were measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

Creatinine, direct bilirubin and total bilirubin were measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

Calcium, potassium, chloride, magnesium, carbon dioxide content/bicarbonate, sodium and urea/BUN were measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

Percentages of basophils, eosinophils, lymphocytes, monocytes and total neutrophils were measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

WBC and platelet counts were measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

Hemoglobin was measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

Hematocrit was measured at Baseline, Day 3 and Day 5 during the treatment period. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value.

The reference ranges for clinical chemistry parameters were ALT 5 to 45 IU/L, ALP 100 to 325 IU/L, creatine kinase 60 to 270 IU/L, AST 10 to 40 IU/L, creatinine 41.548 to 69.836 µmol/L, direct bilirubin 0 to 5.13 µmol/L, total bilirubin 3.42 to 20.52 µmol/L, calcium 2.0958 to 2.5948 mmol/L, CO2/ bicarbonate 19.2 to 27.1 mmol/L, chloride 98 to 108 mmol/L, magnesium 0.7809 to 1.0275 mmol/L, potassium 3.5 to 5 mmol/L, sodium 137 to 147 mmol/L and urea/ BUN 2.856 to 8.211 mmol/L. The baseline assessments were referred to assessments at Day 1. Number of participants with shifts between normal range (NR) high, within NR and NR low values in hematology parameters from baseline (Day 1) at Day 3 and Day 5 is reported.

The reference ranges for hematology parameters were basophils 0 to 2%, eosinophils 0 to 8%, lymphocytes 18 to 49%, monocytes 2 to 10%, total neutrophils 40 to 75%, platelet count 140 to 340 GI/L, WBC count 3.3 to 9 GI/L, hemoglobin 135 to 175 g/L and haematocrit 0.397 to 0.524 ratio. The baseline assessments were referred to assessments at Day 1. Number of participants with shifts between NR high, within NR and NR low values in hematology parameters from baseline (Day 1) at Day 3 and Day 5 is reported.

The normal reference ranges for clinical chemistry and hematology parameters were ALT 5 to 45 IU/L, ALP 100 to 325 IU/L, creatine kinase 60 to 270 IU/L, AST 10 to 40 IU/L, creatinine 41.548 to 69.836 µmol/L, direct bilirubin 0 to 5.13 µmol/L, total bilirubin 3.42 to 20.52 µmol/L, calcium 2.0958 to 2.5948 mmol/L, CO2/ bicarbonate 19.2 to 27.1 mmol/L, chloride 98 to 108 mmol/L, magnesium 0.7809 to 1.0275 mmol/L, potassium 3.5 to 5 mmol/L, sodium 137 to 147 mmol/L, urea/ BUN 2.856 to 8.211 mmol/L, basophils 0 to 2%, eosinophils 0 to 8%, lymphocytes 18 to 49%, monocytes 2 to 10%, total neutrophils 40 to 75%, platelet count 140 to 340 GI/L, WBC count 3.3 to 9 GI/L, hemoglobin 135 to 175 g/L and haematocrit 0.397 to 0.524 ratio. Participants with treatment emergent toxicities for grade 3 (severe) and grade 4 (potentially life threatening) were assessed at Day 1, Day 3 and Day 5. Classification of the toxicities as potentially drug-related was done based on the investigator's judgment.

Vital sign of HR was assessed three times daily during the treatment period/hospitalization at Day 1, Day 2, Day 3, Day 4, Day 5 and Day 6. The baseline assessments were referred to assessments at Day 1. Maximum value in a day is reported where a 'day' is defined as a 24 h period (Treatment Day).

Vital signs of SBP and DBP were assessed three times daily during the treatment period/hospitalization at Day 1, Day 2, Day 3, Day 4, Day 5 and Day 6. The baseline assessments were referred to assessments at Day 1. Minimum value in a day for SBP is reported where a 'day' is defined as a 24 h period (Treatment Day). DBP is measured at the same time as minimum SBP.

Vital signs of OS was assessed three times daily during the treatment period/hospitalization at Day 1, Day 2, Day 3, Day 4, Day 5 and Day 6. The baseline assessments were referred to assessments at Day 1. Minimum value in a day is reported, where a 'day' is defined as a 24 h period (Treatment Day).

Vital signs of RR was assessed three times daily during the treatment period/hospitalization at Day 1, Day 2, Day 3, Day 4, Day 5 and Day 6. The baseline assessments were referred to assessments at Day 1. Maximum value in a day is reported, where a 'day' was defined as a 24 h period (Treatment Day).

Vital signs of temperature was assessed three times daily during the treatment period/hospitalization at Day 1, Day 2, Day 3, Day 4, Day 5 and Day 6. The baseline assessments were referred to assessments at Day 1. Maximum value in a day is reported, where a'day' was defined as a 24 h period (Treatment Day).

12-lead ECG assessments were obtained at Baseline (Day 1) and Day 4 of the treatment period. On Baseline (Day 1), 2 baseline ECGs were obtained prior to study drug infusion. On Day 4, 2 ECGs were obtained, 1 ECG just prior to study drug infusion and 1 ECG at the end of infusion. Overall ECG findings were summarized with regard to visits at Day 1 (pre-dose [ECG 1 and ECG 2]) and Day 4 (pre-dose and 30-min post dose).

12-lead ECG assessments were obtained at Baseline (Day 1) and Day 4 of the treatment period. On Baseline (Day 1), 2 baseline ECGs were obtained. On Day 4, 2 ECGs were obtained, 1 ECG just prior to study drug infusion and 1 ECG at the end of infusion. Overall ECG findings were summarized at Day 1 (ECG 1 and ECG 2) and Day 4 (pre-dose and 30-min post dose).

Absence of fever, improved respiratory status, OS, HR and SBP was defined according to clinical response criteria as: temperature, <= 36.6 degree C-axilla or <= 37.2 degree C-oral or <= 37.7 degree C-rectal and tympanic, without the use of antipyretics within 8 hour; OS of >= 95%; respiratory status of return to pre-morbid oxygen requirement (participants with chronic oxygen use) or need for supplemental oxygen (administered by any modality) to no need for supplemental oxygen or RR <=24 breaths/min without supplemental oxygen; HR <=100 beats/min; SBP of >=90 mmHg without inotropic support within 8 hour. For OS, participants with a history of chronic hypoxia (without supplemental oxygen) satisfied normalization criteria for OS if the value without supplemental oxygen was <=2% from participants historical OS and waiver for participants with a history of chronic supplemental oxygen requirement with baseline OS <95% with supplemental oxygen, recorded within 12 months prior to enrolment.

Clinical response was defined as resolution of at least 4 of the 5 vital signs within the respective resolution criteria of temperature <= 36.6 degree C-axilla or <= 37.2 degree C-oral or <= 37.7 degree C-rectal/ tympanic, without the use of antipyretics within 8 hour; OS of >= 95%; respiratory status of return to pre-morbid oxygen requirement (participants with chronic oxygen use) or need for supplemental oxygen (administered by any modality) to no need for supplemental oxygen or RR <= 24 breaths/min without supplemental oxygen; HR <=100 beats/min; SBP of >= 90 mmHg without inotropic support within 8 h, maintained for at least 24 hour, or hospital discharge, which ever occurred first. Participants discharged from hospital due to clinical improvement/resolution were considered to have met the clinical response endpoint at the time of hospital discharge and were not required to have documented resolution of at least 4 response criteria i.e. achieved success at the time of discharge.

Pre-morbid functional status was defined as the best functional status in the 4 weeks prior to enrolment and status at Baseline (Day 1). The participants were assessed on a 3-point scale by activity level (bed rest, limited ambulation or unrestricted) recorded in thee electronic case report form (eCRF). For participants who were unable to communicate their pre-morbid functional status, the information was requested from another close member of the household or close family member.

The non-invasive ventilator support includes modalities of machine-assisted: continuous positive airway pressure (CPAP) and bi-level positive airway pressure (BiPAP). The invasive ventilator support included modalities of machine-assisted: extra corporeal membrane oxygenation (ECMO) and endotracheal mechanical ventilation. Participants with and without use of modality of invasive, non-invasive ventilatory support and oxygen supplementation was assessed from Baseline (Day 1) to Day 33 (follow-up).

The non-invasive ventilator support includes modalities of machine-assisted: CPAP and BiPAP. The invasive ventilator support included modalities of machine-assisted: ECMO and endotracheal mechanical ventilation. Participants with use of modality of invasive, non-invasive ventilatory support and oxygen supplementation was assessed from Baseline (Day 1) to Day 33 (follow-up).

The duration of ICU stay was assessed from the first day of dosing (Day 1) up to Day 33 (follow-up). Duration in ICU was captured from the eCRF. If the duration in ICU was missing, then the data was set to 0.

The duration of hospital stay was assessed from the first day of dosing (Day 1) up to Day 33 (follow-up). The duration was calculated as duration in hospital = date/time of discharge - date/time of 1st day of dosing.

IC50 value is defined as the concentration of zanamivir required to achieve half maximal inhibition of the influenza viral enzyme neuraminidase of influenza A and B to prevent the release and spread of influenza virus in the respiratory tract. Susceptibility analyses were performed on nasopharyngeal swabs collected on Baseline (Day 1) up to Day 33 (follow-up) depending on the extend of continuation of treatment and duration of hospitalization. Endotracheal aspirates were used in participants who were intubated. Data is categorized for participants with influenza A/H3N2 and influenza B.

A total of 30 neuraminidase gene sequences (23 influenza A/H3N2, 5 influenza B and 2 negative) from 21 participants were obtained from 76 samples. There were no resistance associated neuraminidase mutations or mutations in the neuraminidase active site identified in viruses isolated during this study. Therefore the frequency of resistance emergence to zanamivir could not be determined.

Influenza symptoms were assessed at Baseline (pre-dose): the presence of the following symptoms were recorded: nasal symptoms (rhinorrhea, congestion), feverishness, cough, myalgias, fatigue, diarrhea, anorexia, dyspnea, headache, sore throat, nausea and vomiting. The investigator assessed and recorded influenza symptoms based on interview with the participants. In cases where participants were not able to communicate their symptoms, in participants ventilated and/or sedated, the investigator recorded those signs/symptoms as 'unable to assess'.

Influenza symptoms were assessed at Baseline (pre-dose) and throughout the study period as presence of the following symptoms were recorded: nasal symptoms (rhinorrhea, congestion), feverishness, cough, myalgias, fatigue, diarrhea, anorexia, dyspnea, headache, sore throat, nausea and vomiting. The investigator assessed and recorded influenza symptoms based on interview with the participants. In cases where participants were not able to communicate their symptoms, in participants ventilated and/or sedated, the investigator recorded those signs/symptoms as 'unable to assess'.

The details of complications of influenza like bacterial pneumonia, pneumothorax, pleural effusion, acute respiratory distress syndrome (ARDS), myositis, encephalitis, myocarditis and associated antibiotic use were assessed from Baseline (Day 1) to Day 33 (follow-up). Participants with complications of influenza, with associated use of antibiotics as " associated antibiotic use yes" and without associated use of antibiotics as "associated antibiotic use no" were categorized.

Virologic improvement was defined as a 2 log drop in viral load or sustained undetectable viral ribonucleic acid (RNA), on 2 successive occasions as measured by quantitative reverse transcriptase - polymerase chain reaction (RT-PCR) from nasopharyngeal samples. Assessment was done from Baseline (Day 1) up to Day 33 (follow-up).

Quantitative RT-PCR and quantitative viral culture was carried out on nasopharyngeal swabs collected from Baseline (Day 1) up to Day 33 (follow-up) depending on the extend of continuation of treatment and duration of hospitalization of the participants. Undetectable RNA concentrations were below the level of quantification.

Quantitative RT-PCR and quantitative viral culture was carried out on lower respiratory samples (endotracheal aspirates) collected on Baseline (Day 1) up to Day 33 (follow-up) depending on the extend of continuation of treatment and duration of hospitalization. Endotracheal aspirates were used in participants who were intubated. Undetectable RNA concentrations were below the level of quantification.

Quantitative RT-PCR and quantitative viral culture was carried out on nasopharyngeal swabs collected on Baseline (Day 1) up to Day 33 (follow-up) depending on the extend of continuation of treatment and duration of hospitalization.

Quantitative RT-PCR was carried out on nasopharyngeal swabs collected on Day 1 up to Day 33 (last day) depending on the extend of continuation of treatment and duration of hospitalization. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value. Analysis was done for participants with positive Influenza A RNA and Influenza B RNA. Data is presented for Day 3, Day 5 and last day.

Quantitative viral culture as 50 % tissue culture infectious dose (TCID50) defined as median tissue culture infective dose is that amount of a pathogenic agent that produces pathological change in 50% of cell cultures inoculated. It was carried out on nasopharyngeal swabs collected on Day 1 up to Day 33 (last day) depending on the extend of continuation of treatment and duration of hospitalization. The baseline assessments were referred to assessments at Day 1. Change from Baseline was calculated as the value at the indicated time point minus the Baseline value. Any undetectable viral load values were calculated as x.x Log10 TCID50: x.x Log10 (1.5 or 7.5 was the lower or upper limit of quantification in TCID50). Data is presented for Day 3, Day 5 and last day.