Study of the Safety and Efficacy of STI-5656 (Abivertinib Maleate) in Subjects Hospitalized Due to COVID-19

Inclusion Criteria: * Confirmed positive for COVID-19 by RT-PCR assay or equivalent * Subject or family member/caregiver must have provided written informed consent which includes signing the institutional review board (IRB) or independent ethics committee (IEC) approved consent form prior to participating in any study related activity. However, if obtaining written informed consent is not possible, other procedures as provided in the March 27, 2020 (Updated on July 2, 2020) FDA Guidance on Conduct of Clinical Trials of Medical Products during COVID-19 Pandemic, Question 10, may be used * Able to swallow capsules * Willing to follow contraception guidelines Exclusion Criteria: * Pregnant or breast feeding * Suspected uncontrolled active bacterial, fungal, viral, or other infection other than COVID-19 * Treatment with a strong cytochrome p450 3A4 inhibitor or inducer within 7 days prior to Day 1 * Received anti-rejection or immunomodulatory drugs within 14 days prior to Day 1 * Concurrent participation in another clinical trial involving therapeutic interventions (observation studies are acceptable) * Any condition that confounds the ability to interpret data from the study * Any significant medical condition, laboratory abnormality, or psychiatric illness that would interfere with or prevent the subject from participating in the study