The PJS-539 is a multicentre, phase 2, randomized, double-blind, placebo-controlled clinical trial to evaluate the effect of PJS-539 in the viral load of patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

COVID-19, a disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) became a pandemic in March 2020. Clinically, the coronavirus disease 2019 (COVID-19) ranges from asymptomatic disease in some to severe forms. However, until now, only the use of corticosteroids in selected patients has been shown to improve clinical outcomes in patients with COVID-19.

PJS-539 has been demonstrated to inhibit viral uptake and replication of SARS-CoV-2.

The objective of this Phase II trial is to assess the effect of PJS-539 in the viral load of patients with mild to moderate COVID-19 symptoms.

Inclusion Criteria:

1. Adult patients (age ≥ 18 years);

2. COVID-19 diagnosis confirmed by:

   1. Detection of SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR), or
   2. Rapid genetic or antigen tests validated by Brazilian National Health Surveillance Agency (ANVISA);

3. Mild or moderate symptoms without indication for hospitalization;

4. Symptoms started seven days ago or less;

5. Be able to access the study's online questionnaire.

Exclusion Criteria:

1. Pregnant or lactating women;

2. Known allergy or hypersensitivity to the study drug;

3. Patients at high risk of bleeding, defined by:

   1. Previous Intracranial hemorrhage,
   2. Ischemic stroke in the last 3 months,
   3. Anatomical vascular alteration of the central nervous system known, such as aneurysms or arteriovenous malformations,
   4. Malignant neoplasm of the central nervous system known,
   5. Metastatic solid neoplasia,
   6. Significant closed head or facial trauma in the last 3 months (defined as any trauma that required medical evaluation or hospitalization),
   7. Known intracranial abnormalities not listed as absolute contraindications (e.g., benign intracranial tumor),
   8. Bleeding in the last 2 to 4 weeks (excluding menstrual bleeding),
   9. Surgical procedure in the last 3 weeks,
   10. Current use of full-dose anticoagulants (warfarin, enoxaparin or new anticoagulants) or dual antiplatelet therapy,
   11. Thrombocytopenia (<100,000/mL) or international normalized ratio (INR) > 1.3;

4. Renal failure, defined as glomerular filtration rate (GFR) estimated by the formulas Modification of Diet in Renal Disease (MDRD) or Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) <30 mL/min/1.73m2;

5. Previous participation in the study;

6. History of liver disease (cirrhosis) reported by the patient or in medical records, presence of esophageal varices or presence of ascites;

7. Decompensated heart failure, defined by the presence of dyspnea attributed to cardiac cause, edema of the lower limbs, crackles on pulmonary auscultation or pathological jugular turgency.

8. Participation in other clinical trials with antivirals in COVID-19

The placebo used in this study will consist of the diluent solution used in the interventional drug preparation, which has the same physical characteristics as the interventional drug preparation. All the solutions will be prepared at a central pharmacy and will be sent to each site center in specific boxes containing the necessary regulatory information. The solutions for each study arm will be identified by a random letter from A to I (three letters each arm).