This is a Phase 2 clinical trial in two parts. The first part of the trial will study up to 64 subjects using a dose escalation approach, with 16 subjects per cohort for up to 4 cohorts. The brequinar dose will start at 50 mg per day in Cohort 1, escalating in the next cohort of 16 to 100 mg, then to 150 mg, and finally to 200 mg if safety parameters are met. The dipyridamole dose will be 75 mg three times a day (TID) for subjects assigned to the combination arm for all cohorts. All subjects will also receive standard of care (SOC) for treatment of patients with COVID-19 infection. After identifying the highest brequinar dose that is safe and well tolerated, 48 subjects will be treated in an expansion part comparing the chosen brequinar dose in combination with 75 mg dipyridamole TID to the chosen dose of brequinar alone. The combination of brequinar and dipyridamole shows potent in vitro antiviral activity by blocking DHODH and the pyrimidine salvage pathway, respectively, and the purpose of this study is to establish the safety and antiviral effect of the combination.~During the dose escalation part of the study, subjects with confirmed mild to moderate COVID-19 will receive 5 days of one of the following oral doses: brequinar alone, brequinar in combination with dipyridamole, or placebo. Subjects will have a Screening Visit followed as soon as possible with Study Day 1. Study visits (virtual or in person) will take place at Screening and on specified days. The visits that include bloodwork must be conducted at the study site or arrangements made for sample collection at the subject's home or other appropriate location. Other visits/visit activities for that visit may be conducted remotely using telemedicine or other remote technique. A viral load sample, vital signs (respiratory rate, heart rate, body temperature and SpO2), and a symptom assessment will be completed on specified days.
A Phase 2 multi-center, assessor-blind, randomized study to assess the safety, tolerability, and antiviral activity of brequinar in combination with dipyridamole.