Pfizer Inc. (NYSE: PFE) today announced an agreement with the U.S. government to supply 10 million treatment courses of its investigational COVID-19 oral antiviral candidate, PAXLOVID™ (PF-07321332; ritonavir), subject to regulatory authorization from the U.S. Food and Drug Administration (FDA). If approved or authorized, PAXLOVID, which originated in Pfizer's laboratories, would be the first oral antiviral of its kind, a 3CL protease inhibitor specifically designed to combat SARS-CoV-2. Pfizer is seeking Emergency Use Authorization (EUA) of PAXLOVID with the U.S. FDA; rolling submissions have also commenced in several countries, and the company will continue working to submit applications to regulatory agencies around the world.
Under the terms of the agreement, the U.S. government will acquire 10 million treatment courses to be delivered by Pfizer beginning later this year and concluding in 2022. Pfizer will receive $5.29 billion from the U.S. government, pending and contingent upon regulatory authorization. Pricing for PAXLOVID is based on the principles of advance commitment, volume, equity, and affordability. The price being paid by the U.S. government is reflective of the high committed volume of treatment courses being purchased through 2022. The company has also entered into advance purchase agreements with several other countries and has initiated bilateral outreach to approximately 100 countries around the world.
"We were thrilled with the recent results of our Phase 2/3 interim analysis, which showed overwhelming efficacy of PAXLOVID in reducing the risk of hospitalization among high-risk patients treated within three days of symptom onset by almost 90% and with no deaths, and are pleased the U.S. government recognizes this potential," said Albert Bourla, Chairman and Chief Executive Officer, Pfizer. "It is encouraging to see a growing understanding of the valuable role that oral investigational therapies may play in combatting COVID-19, and we look forward to continuing discussions with governments around the world to help ensure broad access for people everywhere."
PF-07321332 is designed to block the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate, at a stage known as proteolysis - which occurs before viral RNA replication. Co-administration with a low dose of ritonavir helps slow the metabolism, or breakdown, of PF-07321332 in order for it to remain active in the body for longer periods of time at higher concentrations to help combat the virus. In preclinical studies, PF-07321332 did not demonstrate evidence of mutagenic DNA interactions. If authorized or approved, PAXLOVID will be administered at a dose of 300mg (two 150mg tablets) of PF-07321332 with one 100mg tablet of ritonavir, given twice-daily for five days.
Pfizer has also begun and will continue to invest up to approximately $1 billion of its own funds to support the manufacturing and distribution of this investigational treatment candidate, including exploring potential contract manufacturing options. It has entered into advance purchase agreements with several countries and has initiated bilateral outreach to approximately 100 countries around the world. Additionally, Pfizer has signed a voluntary licensing agreement with the Medicines Patent Pool (MPP) to help expand access, pending regulatory authorization or approval, in 95 low- and middle-income countries that account for approximately 53% of the world's population.
The scheduled interim analysis showed an 89% reduction in risk of COVID-19-related hospitalization or death from any cause compared to placebo in patients treated within three days of symptom onset (primary endpoint); 0.8% of patients who received PAXLOVID were hospitalized through Day 28 following randomization (3/389 hospitalized with no deaths), compared to 7.0% of patients who received placebo and were hospitalized or died (27/385 hospitalized with 7 subsequent deaths). The statistical significance of these results was high (p<0.0001). Similar reductions in COVID-19-related hospitalization or death were observed in patients treated within five days of symptom onset; 1.0% of patients who received PAXLOVID were hospitalized through Day 28 following randomization (6/607 hospitalized, with no deaths), compared to 6.7% of patients who received a placebo (41/612 hospitalized with 10 subsequent deaths), with high statistical significance (p<0.0001). In the overall study population through Day 28, no deaths were reported in patients who received PAXLOVID as compared to 10 (1.6%) deaths in patients who received placebo.
The review of safety data included a larger cohort of 1,881 patients in EPIC-HR, whose data were available at the time of the analysis. Treatment-emergent adverse events were comparable between PAXLOVID (19%) and placebo (21%), most of which were mild in intensity. Among the patients evaluable for treatment-emergent adverse events, fewer serious adverse events (1.7% vs. 6.6%) and discontinuation of study drug due to adverse events (2.1% vs. 4.1%) were observed in patients dosed with PAXLOVID compared to placebo, respectively.
In July 2021, Pfizer initiated the first of these trials, known as EPIC-HR, a randomized, double-blind study of non-hospitalized adult patients with COVID-19, who are at high risk of progressing to severe illness. At the recommendation of an independent Data Monitoring Committee and in consultation with the U.S. FDA, Pfizer has ceased further enrollment into the study due to the overwhelming efficacy demonstrated in these results.
In August 2021, Pfizer began the Phase 2/3 EPIC-SR (Evaluation of Protease Inhibition for COVID-19 in Standard-Risk Patients), to evaluate efficacy and safety in patients with a confirmed diagnosis of SARS-CoV-2 infection who are at standard risk (i.e., low risk of hospitalization or death). EPIC-SR includes a cohort of vaccinated patients who have an acute breakthrough symptomatic COVID-19 infection and who have risk factors for severe illness. In September, Pfizer initiated the Phase 2/3 EPIC-PEP (Evaluation of Protease Inhibition for COVID-19 in Post-Exposure Prophylaxis) to evaluate efficacy and safety in adults exposed to SARS-CoV-2 by a household member. These trials are ongoing.
For more information on the EPIC Phase 2/3 clinical trials for PAXLOVID, visit