Business & Finance
Pfizer Seeks Emergency Use Authorization for Novel COVID-19 Oral Antiviral Candidate
17 November 2021 - - US-based pharmaceutical company Pfizer Inc (NYSE: PFE) is seeking Emergency Use Authorization of its investigational oral antiviral candidate, Paxlovid (PF-07321332; ritonavir), for the treatment of mild to moderate COVID-19 in patients at increased risk of hospitalizations or death, the company said.

This submission to the US Food and Drug Administration includes clinical data from the Phase 2/3 EPIC-HR (Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients) interim analysis. Rolling submission of non-clinical data for Paxlovid was initiated with the US FDA in October 2021.

If authorized or approved, Paxlovid would be the first oral antiviral of its kind, a 3CL protease inhibitor specifically designed to combat SARS-CoV-2 that could be prescribed as an at-home treatment to high-risk patients at the first sign of infection, potentially helping patients avoid severe illness which can lead to hospitalization and death.

Pfizer is seeking EUA for Paxlovid based on positive results from the EPIC-HR interim analysis, which enrolled non-hospitalized adults aged 18 and older with confirmed COVID-19 who are at increased risk of progressing to severe illness.

The data demonstrated an 89% reduction in risk of COVID-19-related hospitalization or death from any cause in patients treated with Paxlovid compared to placebo within three days of symptom onset, with no deaths in the treatment group.

Similar results were seen with within five days of symptom onset.

Treatment-emergent adverse events were comparable between Paxlovid and placebo, most of which were mild in intensity.

At the recommendation of an independent Data Monitoring Committee, and in consultation with the US FDA, Pfizer ceased further enrollment into the study due to the overwhelming efficacy demonstrated.

Rolling submissions have commenced in several countries including in the United Kingdom, Australia, New Zealand and South Korea, with planned submissions to other regulatory agencies around the world to follow.

Pfizer has begun and will continue to invest up to approximately USD 1bn of its own funds to support the manufacturing and distribution of this investigational treatment candidate.

Additionally, Pfizer has signed a voluntary licensing agreement with the Medicines Patent Pool 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.

Paxlovid is an investigational SARS-CoV-2 protease inhibitor antiviral therapy. It was specifically designed to be administered orally so that it can be prescribed at the first sign of infection or at first awareness of an exposure potentially helping patients avoid severe illness (which can lead to hospitalization and death), experience a decreased symptomatic period, or avoid disease development following contact.

PF-07321332 is designed to block the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate.

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.

PF-07321332 inhibits viral replication at a stage known as proteolysis, which occurs before viral RNA replication.

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.