A Phase 2b/3, Randomized, Double Blind, Placebo Controlled, Adaptive Design Study to Evaluate the Efficacy and Safety of Leronlimab for Patients With Severe or Critical Coronavirus Disease 2019 (COVID-19)

• Male or female adult ≥ 18 years of age at time of screening.

• Subjects hospitalized with severe or critical illness caused by coronavirus 2019 infection as defined below:

• A. Severe Illness:

‣ Diagnosed with COVID-19 by standard RT-PCR assay or equivalent testing within 5 days of screening

• AND

• Symptoms of severe systemic illness/infection with COVID-19:

‣ At least 1 of the following: fever, cough, sore throat, malaise, headache, muscle pain, shortness of breath at rest or with exertion, confusion, or symptoms of severe lower respiratory symptoms including dyspnea at rest or respiratory distress

• AND

• Clinical signs indicative of severe systemic illness/infection with COVID-19, with at least 1 of the following:

‣ RR ≥ 30, HR ≥ 125, SaO2 \<93% on room air or requires \> 2L oxygen by NC in order maintain SaO2 ≥93%, PaO2/FiO2 \<300

• AND

‣ None of the following: Respiratory failure (defined by endotracheal intubation and mechanical ventilation, oxygen delivered by high-flow nasal cannula, noninvasive positive pressure ventilation, or clinical diagnosis of respiratory failure in setting of resource limitations), Septic shock (defined by SBP \< 90 mm Hg, or Diastolic BP \< 60 mm Hg), Multiple organ dysfunction/failure

• B. Critical Illness:

‣ Diagnosed with COVID-19 by standard RT-PCR assay or equivalent testing within 5 days of screening

• AND

• Evidence of critical illness, defined by at least 1 of the following:

‣ Respiratory failure defined based on resource utilization requiring at least 1 of the following: Endotracheal intubation and mechanical ventilation, oxygen delivered by high-flow nasal cannula, noninvasive positive pressure ventilation, ECMO, or clinical diagnosis of respiratory failure (in setting of resource limitation)

• OR

‣ Shock (defined by SBP \< 90 mm Hg, or Diastolic BP \< 60 mm Hg or requiring vasopressors)

• OR

⁃ Multiple organ dysfunction/failure

• Subject, if intubated, positive endexpiratory pressure (PEEP) \<15 cmH2O with PaO2/FiO2 \>150 mmHg.

• Electrocardiogram (ECG) with no clinically significant findings as assessed by the Investigator

• Subject (or legally authorized representative) provides written informed consent prior to initiation of any study procedures.

• Understands and agrees to comply with planned study procedures.

• Women of childbearing potential and their partner must agree to use at least one highly effective method of contraception (e.g., hormonal contraceptives \[implants, injectables, combination oral contraceptives, transdermal patches, or contraceptive rings\], intrauterine devices, bilateral tubal occlusion, or sexual abstinence) for the duration of the study.