This clinical study was designed to assess the efficacy and safety of MAS825 for the treatment of severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infected patients with coronavirus disease 2019 (COVID-19) pneumonia and impaired respiratory function.

This was a Phase 2, randomized, placebo -controlled, participant and investigator blinded, multi-center study to assess efficacy and safety of MAS825 for the treatment of SARS-CoV-2 infected patients with COVID-19 pneumonia and impaired respiratory function.

The study consisted of five study periods:

Screening / Baseline / Treatment visit (Day -1 to 1): Lasted up to a maximum of 24 hours and comprised a screening / baseline assessment. This visit was used to confirm that the study inclusion and exclusion criteria were met and served as baseline assessment prior to randomization. Participants were randomized as soon as possible, but within a maximum of 24 hours after screening in a 1:1 ratio receiving a single intravenous infusion of MAS825 or placebo in addition to standard of care (SoC) on Day -1 to 1.

Treatment period (Day 2-15): Study assessments were conducted every 2 days for hospitalized participants. If participants were discharged from the hospital prior to Day 15, assessments on the day of discharge were performed according to the schedule listed under Day 15 and those participants returned to the site for the Day 15 assessment (all other visits between discharge and Day 15 were omitted).

Follow-up (Day 16-29): After completion of the treatment period, participants were observed until Day 29 or discharged from hospital, whichever was sooner. Study assessments were conducted every 2 days for domiciled participants. If participants were discharged from hospital prior to Day 29, a study visit conducted by telephone was performed on Day 29 (all other visits between discharge and Day 29 were omitted).

Safety follow-up visit assessment (Day 45): A follow-up visit for safety was conducted at Day 45 if the participant was hospitalized. If participants were discharged from the hospital prior to Day 45, a study visit was conducted by telephone on Day 45.

End of Study/Safety follow-up visit assessment (Day 127): A follow-up visit for safety was conducted at Day 127 if the participant was hospitalized. If participants were discharged from the hospital prior to Day 127, a study visit was conducted by telephone on Day 127.

Inclusion Criteria:

1. Male and female patients aged ≥18 years at screening
2. Signed Informed Consent Form (ICF) by patient capable of giving consent, or, when the patient is not capable of giving consent, by his or her legal/authorized representative (if allowed according to local requirements)
3. Clinically diagnosed with the SARS-CoV-2 virus by polymerase chain reaction (PCR) or by other approved diagnostic methodology within 7 days prior to randomization
4. Hospitalized with COVID-19-induced pneumonia evidenced by chest x-ray, computed tomography scan (CT scan) or magnetic resonance scan (MR scan) (taken within 5 days prior to randomization)
5. Impaired respiratory function, defined as peripheral oxygen saturation (SpO2) ≤93% on room air or partial pressure of oxygen (PaO2) / fraction of inspired oxygen (FiO2) <300 millimeter of mercury (mmHg) at time of screening For cities located at altitudes greater than 2500 m above sea level, these will be substituted with SpO2 <90% and PaO2/FiO2 <250 mmHg
6. Acute Physiologic Assessment and Chronic Health Evaluation (APACHE) II score of ≥10 at time of screening
7. CRP ≥20 mg/L or ferritin level ≥600 μg/L at screening
8. Body weight between 45 kg and 145 kg, inclusive, at screening
9. Ability to comply with the study protocol, in the investigator's judgment

Exclusion Criteria:

1. History of hypersensitivity to the investigational treatment or their excipients or to drugs of similar chemical classes

2. Suspected active or chronic bacterial (including Mycobacterium tuberculosis), fungal, viral, or other infection with the exception of SARS-CoV-2

3. In the opinion of the investigator, progression to death is imminent and inevitable within the next 24 hours, irrespective of the provision of treatment

4. Intubated prior to randomization

5. Patients who have explicitly expressed the wish not to receive intensive care support when this would be indicated based on their condition

6. Previous treatment with anti-rejection and immunomodulatory drugs within the past 2 weeks, or within the past 30 days or 5 half-lives (whichever is the longer) for immunomodulatory therapeutic antibodies or prohibited drugs, with the exception of anti-viral therapies or corticosteroids

   • For COVID-19 infection, ongoing corticosteroid treatment is permitted at doses as per local SoC
   • For non-COVID-19 disorders, ongoing corticosteroid treatment is permitted at doses up to and including prednisolone 10 mg daily or equivalent.

7. Serum alanine transaminase (ALT) or aspartate transaminase (AST) >5 times upper limit of normal detected within 24 hours at screening/baseline (according to local laboratory reference ranges) or other evidence of severe hepatic impairment.

8. Absolute peripheral blood neutrophil count of ≤1000/mm^3

9. Estimated GFR (eGFR) ≤30 mL/min/1.73m^2 (based on CKD-EPI formula)

10. Pregnant or breastfeeding, or positive urine or serum pregnancy test in a pre-dose examination

11. 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

12. Women of child-bearing potential, defined as all women physiologically capable of becoming pregnant, unless they agree to abstain from any sexual intercourse for a total of 29 days after randomization (the 14-day treatment period plus a 14-day follow-up period).

13. Current participation in any other investigational trials, with the exception of (not yet) approved COVID-19 therapies that are considered (local) standard of care.

Novartis is committed to sharing with qualified external researchers, access to patient-level data and supporting clinical documents from eligible studies. These requests are reviewed and approved by an independent review panel on the basis of scientific merit. All data provided is anonymized to respect the privacy of patients who have participated in the trial in line with applicable laws and regulations.

This trial data availability is according to the criteria and process described on www.clinicalstudydatarequest.com.