This study is a prospective, phase II, multi-center, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of mavrilimumab in hospitalized patients with acute respiratory failure requiring oxygen supplementation in COVID- 19 pneumonia and a hyper-inflammatory status. The study will randomize patients to mavrilimumab or placebo, in addition to standard of care per local practice. The total trial duration will be 12 weeks after single mavrilimumab or placebo dose.

To evaluate the efficacy and safety of mavrilimumab versus placebo in addition to best standard of care (SoC) in the treatment of COVID-19 pneumonia.

As of May 13, 2020, COVID-19 has been confirmed in more than 4.2 million people worldwide. Mortality rate has been reported to be approximately 3.7%, which is nearly 4 times higher than that of influenza: there is an urgent need for effective treatment.

Accumulating evidence suggests that patients with severe acute COVID-19 pneumonia have a cytokine storm syndrome, or unbalanced hyper-inflammatory response resulting in markedly elevated cytokine and chemokine production.

GM-CSF is a cytokine with dual roles as a critical pulmonary hormone and proinflammatory properties that can exaggerate tissue inflammation. Recent preliminary uncontrolled clinical observations on 13 non-mechanically-ventilated patients in the promoter institution suggest that GM-CSF pathway blockade with mavrilimumab is an effective and well-tolerated treatment for COVID-19 pneumonia.

We will perform a prospective, phase II, multi-center, randomized, double-blind, placebo-controlled trial to evaluate the efficacy and safety of mavrilimumab in hospitalized patients with acute respiratory failure requiring oxygen supplementation in COVID- 19 pneumonia and a hyper-inflammatory status. The study will randomize non-mechanically-ventilated adult patients to mavrilimumab or placebo, in addition to standard of care per local practice, which may include but not limited to anti-viral treatment, hydroxychloroquine, low-dose corticosteroids (≤ 10 mg of prednisone or equivalent) and/or supportive care. The total trial duration will be 12 weeks after single mavrilimumab or placebo infusion. Safety will be closely monitored by a dedicated external data safety monitoring board (DSMB) at regular intervals during the study.

Inclusion Criteria:

• Adults (≥ 18 years of age)

• Signed informed consent by any patient capable of giving consent, or, when the patient is not capable of giving consent, by his or her legal/authorized representative or according to local guidelines

• Patients clinically diagnosed with SARS-CoV-2 virus by PCR or by other approved diagnostic methodology

• Hospitalized with COVID-19-induced pneumonia evidenced by chest x-ray or CT scan with pulmonary infiltrates

• Patient requiring oxygen supplementation (i.e. with a SpO2 ≤ 92% while breathing room air) and having a PAO2/FIO2 ratio ≤ 300 mmHg

• Lactate dehydrogenase (LDH) > normal range and at least one of the following:

  1. fever > 38.0 °C;
  2. increased levels of C-reactive Protein (CRP) ≥ 10x UNL mg/L (≥ 60 mg/l);
  3. increased levels of ferritin ≥ 2.5x UNL ( ≥ 1000 μg/L)

Exclusion Criteria:

• Onset of COVID-19 pneumonia symptoms (i.e. dyspnea/respiratory insufficiency) >14 days

• On mechanical ventilation at the time of randomization

• A PaO2/FiO2 < 100 mmHg

• Uncontrolled systemic infection (other than COVID-19)

• Hypersensitivity to the active substance or to any of the excipients of the experimental drug

• Total neutrophil count < 1500/mm3

• Severe hepatic cirrhosis

• History of chronic HBV or HCV infection

• Known or active tuberculosis (TB) or a history of incompletely treated TB; suspected or known extrapulmonary tuberculosis

• Moderate/severe heart failure (NYHA Class 3 or 4)

• Any prior (within the defined periods below) or concurrent use of immunosuppressive therapies including but not limited to the following:

  1. Anti-IL-6, anti-IL-6R antagonists or Janus kinase inhibitors (JAKi) in the past 30 days or plans to receive during the study period;
  2. Cell-depleting agents (e.g., anti CD20) without evidence of recovery of B cells to baseline level;
  3. Anakinra within 1 week of baseline; canakinumab within 8 weeks of baseline; abatacept within 8 weeks of baseline.
  4. Tumor necrosis factor (TNF) inhibitors within 2-8 weeks (etanercept within 2 weeks, infliximab, certolizumab, golimumab, or adalimumab within 8 weeks), or after at least 5 half-lives have elapsed, whichever is longer;
  5. Alkylating agents including cyclophosphamide (CYC) within 6 months of baseline;
  6. Cyclosporine (CsA), azathioprine (AZA) or mycophenolate mofetil (MMF) or leflunomide or methotrexate within 4 weeks of baseline.

• Pregnancy or lactation (Note: Women of childbearing age should use effective contraception/abstinence after treatment with mavrilimumab and for 3 months after the dosing)

• Any serious medical condition or abnormality of clinical laboratory tests that, in the investigator's judgment, precludes the patient's safe participation in and completion of the study

• In the opinion of the investigator, progression to death is imminent and highly likely within the next 24 hours, irrespective of the provision of treatments

• Current participation in any other interventional investigational trials