A PHASE 2 RANDOMIZED, DOUBLE-BLIND, PLACEBO-CONTROLLED TRIAL OF MHAA4549A, A MONOCLONAL ANTIBODY, ADMINISTERED AS MONOTHERAPY FOR THE TREATMENT OF ACUTE UNCOMPLICATED SEASONAL INFLUENZA A INFECTION IN OTHERWISE HEALTHY ADULTS

INTERVENTION: Product Name: MHAA4549A Product Code: MHAA4549A/RO6876802 Pharmaceutical Form: Concentrate for solution for infusion INN or Proposed INN: n.a. CAS Number: n.a. Current Sponsor code: MHAA4549A/RO6876802 Other descriptive name: [anti‐Influenza A, 39.29] Concentration unit: mg milligram(s) Concentration type: equal Concentration number: 500‐ Pharmaceutical form of the placebo: Solution for infusion Route of administration of the placebo: Intravenous use CONDITION: acute uncomplicated seasonal influenza ; MedDRA version: 19.0 Level: LLT Classification code 10022002 Term: Influenza A virus infection System Organ Class: 100000004862 ; MedDRA version: 19.0 Level: LLT Classification code 10022001 Term: Influenza (epidemic) System Organ Class: 100000004862 ; MedDRA version: 19.0 Level: LLT Classification code 10016790 Term: Flu System Organ Class: 100000004862 Therapeutic area: Diseases [C] ‐ Virus Diseases [C02] PRIMARY OUTCOME: Main Objective: To evaluate the safety and tolerability of a single IV dose of MHAA4549A as compared to placebo when administered in otherwise healthy patients with acute uncomplicated seasonal influenza A, focusing on the following:; •Nature, frequency, and severity of serious and non‐serious adverse events; •Effects on laboratory values, vital signs, ECG parameters, and other safety biomarkers Primary end point(s): Incidence, nature, and severity of adverse events and clinical laboratory abnormalities associated with the administration of MHAA4549A to patients with influenza A as measured by changes in vital signs, physical findings, and clinical laboratory results Secondary Objective: To examine the time to alleviation of clinical signs and symptoms of influenza A; infection; • To examine the severity of clinical signs and symptoms of influenza A infection; • To measure hospital admission rate; • To measure duration of hospital stay; • To measure antibiotic usage for secondary bacterial respiratory infections; • To measure the frequency, severity and development of secondary complications of influenza (pneumonia, exacerbation of chronic lung disease, myocarditis, acute respiratory distress syndrome, acute otitis media, other related complications); • To measure the incidence of death; • To measure influenza re‐infection rate Timepoint(s) of evaluation of this end point: From Baseline to Day 100 SECONDARY OUTCOME: Secondary end point(s): •Time to alleviation of sign/symptoms of influenza A infection as defined by a rating of 1 or less (mild or none) for each symptom on a 4‐point symptom scale [ Time Frame: From Baseline to Day 14 ] ; •Percentage of participants requiring hospitalization for influenza‐related complications ; •Duration of hospitalization for influenza‐related complications ; •Percentage of participants with influenza‐related deaths; •Percentage of participants requiring antibiotics for secondary bacterial infections ; •Percentage of participants with influenza‐related complications ; •Percentage of participants with influenza A relapse or reinfection ; •PK measurements in serum (including Cmax, AUC, systemic clearance, volume of distribution, and half‐life) Timepoint(s) of evaluation of this end point: From Baseline to Day 100 unless otherwise noted INCLUSION CRITERIA: •Otherwise healthy adults •Positive test for influenza A infection •No more than 3 days elapsed between onset of influenza‐like illness and start of study drug •Presence of at least one moderate or severe constitutional symptom such as headache, myalgia, fever, chills, fatigue, anorexia, or nausea PLUS one moderate or severe respiratory symptom such as cough, sore throat, or rhinorrhea •For women of childbearing potential: negative pregnancy test and agreement to use acceptable contraceptive methods for at least 120 days after study drug administration •For men: agreement to use acceptable contraceptive methods for at least 30 days after study drug administration Are the trial subjects under 18? no Number of subjects for this age range: F.1.2 Adults (18‐64 years) yes F.1.2.1 Number of subjects for this age range 100 F.1.3 Elderly (>=65 years) yes F.1.3.1 Number of subjects for this age range 41