The agent was withdrawn from development by the manufacturer after being placed on clinical hold by the US FDA.

This study looks at the safety and effectiveness of PF-07304814 in treating COVID-19 in people who have been hospitalized with the infection. Participants in the study will be treated with either PF-07304814 plus current standard of care (SOC), or with placebo plus current SOC. This is ACTIV-3/TICO Treatment Trial H6.

This is a treatment trial of the ACTIV-3/TICO master protocol (NCT04501978) to evaluate the safety and efficacy of PF-07304814 in hospitalized patients infected with COVID-19.

This is a randomized, blinded, controlled sub-study of PF-07304814 plus current SOC against placebo plus current SOC. The placebo arm may be shared across other sub-studies of the ACTIV-3/TICO master protocol. When more than one drug is being tested at the same time, participants will be randomly allocated to treatments or placebo.

Randomization will be stratified by study site pharmacy and disease severity. There are 2 disease severity strata: participants without organ failure (severity stratum 1) and participants with organ failure (severity stratum 2).

An independent Data and Safety Monitoring Board (DSMB) will regularly review interim analyses and summarize safety and efficacy outcomes. The pace of enrollment with be initially restricted, and there will be an early review of safety data by the DSMB. At the outset of the trial, only participants in disease severity stratum 1 will be enrolled. This will continue until approximately 300 participants are enrolled and followed for 5 days. The exact number will vary according to the speed of enrollment and the timing of DSMB meetings. Prior to expanding enrollment to also include patients in disease severity stratum 2, safety will be evaluated and a pre-specified futility assessment by the DSMB will be carried out using 2 ordinal outcomes assessed at Day 5.

If PF-07304814 passes the futility assessment, enrollment of participants will be expanded, seamlessly and without any data unblinding, to include participants in disease severity stratum 2 as well as those in disease severity stratum 1. Future interim analyses will be based on the primary endpoint of sustained recovery and will use pre-specified guidelines to determine early evidence of benefit, harm, or futility for the investigational agent. Participants will be followed for 18 months following randomization.

This trial will be conducted in several hundred clinical sites. Participating sites are affiliated with networks funded by the United States National Institutes of Health (NIH) and the US Department of Veterans Affairs.

Inclusion Criteria: Refer to the master protocol (NCT04501978)

Exclusion Criteria: Refer to the master protocol (NCT04501978)

Additional Exclusion Criteria:

1. Participants with moderate to severe hepatic impairment (i.e. Child-Pugh class B or C) or acute liver failure.

2. Participants receiving any medications or substances that are strong inhibitors or inducers of cytochrome P450 (CYP) 3A4 (see Section H6.3.4).

3. Patients will be excluded if taking drugs which have a narrow therapeutic window that are substrates of CYP3A4, including but not limited to: astemizole, cisapride, cyclosporine, dihydroergotamine, ergotamine, pimozide, quinidine, sirolimus, tacrolimus, and terfenadine.

4. Pregnant women

5. Nursing mothers

6. Women of child-bearing potential who are unwilling to acknowledge the strong advice to abstain from sexual intercourse with men or practice appropriate contraception through 5 weeks of the study.

7. Men who are unwilling to acknowledge the strong advice to abstain from sexual intercourse with women of child-bearing potential or to use barrier contraception through 5 weeks of the study.

8. Patients with a history of deep vein thrombosis or pulmonary thrombotic embolism*.

   • Prior to the initial futility assessment, which is performed when approximately 150 patients have been enrolled on PF-07304814 and 150 on placebo, patients with a history of deep vein thrombosis or pulmonary embolism will be excluded. These patients will be eligible for the trial if the initial futility assessment is passed by this agent, and if risk-benefit is favorable based on an assessment of available data that is reviewed by the independent DSMB. These data will include treatment comparisons of thromboembolic events and coagulation markers, and any additional data from studies carried out by Pfizer.