The study comprises of a 4-week (±2 weeks) screening period, a 24-week treatment period and a 12-week follow-up period. Approximately 100 subjects who meet the criteria for study entry are planned to be enrolled to the study. Eligible subjects will be randomized to receive placebo or FB825 in a 1:1 ratio with 50 subjects in each arm.~Eligibility will be checked in patients with allergic asthma during the 4-week (±2 weeks) screening period. Potential candidates should provide signed informed consent forms before starting any screening activities. The subjects will receive one dose of 8 mg/kg FB825 or placebo, and five doses of 4 mg/kg FB825 or placebo every 4 weeks subsequently. The study drug will be administered as a 1-hour IV infusion.~Patients may administer albuterol (or equivalents) as rescue medications as needed throughout the study.~Prior to screening, patients must be on a stable dose of any of formulations of inhaled corticosteroids (ICS)/long-acting beta-agonist (LABA) combination therapy for at least 1 month, including Fluticasone/salmeterol, Budesonide/formoterol, or Mometasone/formoterol. Patients who have been on budesonide/formoterol or mometasone/formoterol will be switched to an equivalent dose of fluticasone/salmeterol at randomization (Day 1), and patients who have been on fluticasone/salmeterol will remain on their current treatment as background therapy.~ICS/LABA (fluticasone/salmeterol) combination therapy during background therapy stable phase (Day 1 to Day 28) followed by ICS only (fluticasone) during ICS tapering phase (Day 29 to Day 140), and than followed by the FB825 monotherapy phase (Day 141 to Day 168).~Upon completing 24 weeks of treatment with the investigational product, patients will be placed on their original dose of fluticasone/salmeterol combination therapy (dose at study entry) and albuterol (or equivalents) (as needed) to control their symptoms.~Occurrence of an exacerbation of asthma will be evaluated as the primary endpoint at week 24. Mean change in morning PEF and the occurrence of an exacerbation of asthma at other time points will also be evaluated as the secondary endpoint in the study. Exacerbation of asthma as defined by any of the following:~A 30% or greater reduction from baseline in morning peak expiratory flow (PEF) on 2 consecutive days, or~≥6 additional reliever puffs of albuterol (or equivalents)in a 24 hour period (compared to baseline) on 2 consecutive days or,~Deterioration of asthma, as determined by the investigator, requiring:~Systemic (oral and/or parenteral) steroid treatment, or~An increase of ICS usage by ≥4 times of the protocol-defined dose (refer to 5.1.3 background therapy table) at each phase throughout the study period, or~Hospitalization, or~ER (emergency room visit) due to asthma attack~Subjects will have site visits after receiving study drug for efficacy, safety, and biomarker evaluation (see Study Flow Chart). Subjects who prematurely withdraw from the study will have an end of study (EOS) visit within 7 days. The daily status of subject, such as peak flow, will be recorded in the e-diary every day during the study. PI can ask the subject for an unscheduled visit any time if any abnormal status reported on the e-diary. The e-diary system will send a notification to the PI automatically once the subject meets the protocol defined exacerbation of asthma.~Relative change in pre-bronchodilator FEV1 , post-bronchodilator FEV1, and asthma symptoms will be evaluated during the study.~Immunologic biomarkers including changes from baseline in total IgE, allergen-specific IgE, blood eosinophils, exhaled NO, mIgE B cell counts, Immunoglobulin G (IgG)2, Immunoglobulin G (IgG)4, and cytokines such as serum thymus and activation-regulated chemokine (TARC), periostin and eotaxin-3, will be measured and evaluated. Adverse events will be checked and recorded at every visit. Laboratory tests, vital signs and physical examinations will be performed as scheduled and will also be used in safety evaluation.~Serum levels of FB825 for pharmacokinetic assessments will be measured via intensive and sparse PK. For intensive PK, 24 subjects (12 subjects of each Arm) participate in the intensive PK sub-study, serum samples will be collected at 0.5 hour pre-dose and at 0.5, 1, 1.25, 2, and 4 hours after the start of infusion on dosing days at Visits 2 and 9, and a single collection at any time on Visit 3 and Visit 10. For sparse PK, all other subjects will participate in the sparse pharmacokinetic (PK) assessments, serum samples will be collected at 0.5 hour pre-dose and at 1.25 hour after the start of infusion at Visits 2 and 9. Serum samples will be collected at 0.5 hour pre-dose and at 1.25 hour after the start of infusion at Visits 5, 6, 7 and 8, and a single collection will be conducted at Visits 4 as well as at follow-up Visits 11, 12, 13 and 14 for intensive and sparse PK.~IgE (total IgE and allergen-specific IgE) will be analyzed and serum samples will be collected at all visits during treatment and follow-up periods. IgG2, IgG4, and biomarkers (e.g. TARC, eotaxin-3, and periostin), will be measured and collected at all Visits except visit 1.~Peripheral Blood Mononuclear Cells (PBMC) analysis (assessing the mIgE B cell counts) will be measured at Visits 2, 4, 5, 7, 9, 11, 13 and 14.~Serum anti-drug antibodies (ADAs) will be assessed in samples before infusion at Visits 2, 7, and 9, and at any time at Visits 11, 13 and 14.~For risk management of the sponsor, independent Data Safety Monitoring Board (DSMB) meetings will be conducted to evaluate participant safety data during the study. The DSMB will be conducted in one month after the visit 2 of 10th, 30th, and 80th randomized patient. Unscheduled meetings may be recommended and initiated by the DSMB Chairperson, the sponsor, or the principal investigator.
This is a randomized, placebo-controlled and double-blind study to evaluate the efficacy and safety of FB825 in adult patients with moderate-to-severe allergic asthma.