Study to Select the Dose and Evaluate Safety and Efficacy of Monoclonal Antibody in Adult With Recently Diagnosed Asymptomatic to Moderately Severe COVID-19.

Overview

MAD0004J08, the experimental drug, is a potent neutralizing IgG1 monoclonal antibody (mAb) targeting the spike protein of SARS-CoV-2. MAD0004J08 blocks viral attachment and entry into human cells and neutralizes the virus. Because of its high affinity and potency, MAD0004J08 may accelerate clearance of the virus and prevent clinical deterioration of COVID-19 patients, especially when administered shortly after infection, and prevent SARS-CoV-2 infection in uninfected subjects. Because of its high potency, MAD0004J08 is expected to be effective at low doses (mg range) and thus will be administered by intramuscular (IM) injection, as opposed to the intravenous bolus required by high dose mAbs. The goals of this Phase II-III seamless adaptive clinical trial are: Stage-1 (Phase II) 1. Select one dose level for progression to Stage-2 Stage-1 + Stage-2 (Phase III) 2. Provide confirmatory evidence of safety and efficacy for regulatory approval.

This clinical trial is designed as a randomized, stratified, placebo-controlled doubleblind, multicenter, seamless adaptive study. The target study population is adult patients ≥ 18 years of age with recently diagnosed (≤ 3 days from 1st positive swab taken) asymptomatic to moderately severe COVID-19 at baseline. Patients with comorbidities will be allowed in the study assuming all inclusion and exclusion criteria are met. Participants will not require hospitalization at baseline. The trial is designed in two stages: * Stage I: participants will be randomized (1:1:1 ratio) to one of the one of the following three study cohorts: * MAD0004J08 400 mg, single dose * MAD0004J08 100 mg, single dose * Placebo, single dose The collected data will be analysed following a pre-planned interim analysis plan. Based on the results of this analysis the Data Monitoring Committee (DMC) will recommend whether the study should advance to Stage-2, and if so, will recommend selection of one of the two MAD0004J08 treatments for Stage-2. Alternatively, the DMC will recommend stopping the study. Final decisions will be made by an unblinded sub-group of the Steering Committee (SC), including senior Sponsor representatives, based on summary results. * Stage-2: participants will be randomized (1:1 ratio) to one of two treatments: * MAD0004J08, dose level selected in Stage-1, single dose * Placebo, single dose Twelve (12) study visits and 2 telephone calls are scheduled for each participant over approximately 168 days. Additional ad-hoc visit(s) may be necessary to confirm eradication of SARS-CoV-2 from the upper respiratory tract (URT) following the 1st negative swab. At Visit 1 (baseline) all participants will undergo testing for serum IgA and IgG vs. the spike (S) protein, and IgG vs. nucleocapsid (N) protein: participants testing negative to all three antibodies at baseline are referred to as seronegative; participants testing positive to any of the three antibodies at baseline are referred to as seropositive. Due to the need to minimize time between diagnosis and intervention, screening procedures, baseline procedures, randomization and administration of study treatment will occur on day 1. Visits from Day 3 to Day 21 (Visits 2 to 9) will be conducted by study staff at the participant's home, unless the participant is hospitalized. Visits from Day 28 to Day 168 (Visits 10 to 12) will be conducted at the study center. Participants requiring hospitalization during the study period are to be hospitalized at the study center where Visit 1 was conducted. At each scheduled visit nasopharyngeal swabs will be carried out. Additional swabs may be taken ad hoc to confirm eradication after the 1st negative swab. Safety and efficacy endpoints will be analyzed as appropriate in two target populations (all randomized participants (ALL) and seronegative randomized participants (SEROneg) and three time-windows ( baseline (Visit 1) to end of Stage-1 or dropout (interim analysis), baseline (Visit 1) to end of Stage-2 or dropout (primary analysis) and baseline (Visit 1) to end of study (Visit 12) or dropout (final analysis).