Pfizer has released final data from its EPIC-SR (Evaluation of Protease Inhibition for COVID-19 in Standard-Risk Patients) Phase II/III study. The findings reportedly confirm earlier results of interim analysis showing its Paxlovid treatment (nirmatrelvir and ritonavir tablets) reduced the risk of hospitalization or death by 89% (within three days of symptom onset) and 88% (within five days of symptom onset) compared to placebo; additionally, it showed no deaths compared to placebo in non-hospitalized, high-risk adults with COVID-19.
“This news provides further corroboration that our oral antiviral candidate, if authorized or approved, could have a meaningful impact on the lives of many, as the data further support the efficacy of Paxlovid in reducing hospitalization and death and show a substantial decrease in viral load,” said Albert Bourla, CEO and chairman of Pfizer. “This underscores the treatment candidate’s potential to save the lives of patients around the world.”
“Emerging variants of concern, like omicron, have exacerbated the need for accessible treatment options for those who contract the virus,” Bourla added. “We are confident that, if authorized or approved, this potential treatment could be a critical tool to help quell the pandemic.”
Pfizer also reported 0.7% of patients who received Paxlovid were hospitalized through Day 28 following randomization (5/697 hospitalized with no deaths), compared to 6.5% of patients who received placebo and were hospitalized or died (44/682 hospitalized with nine subsequent deaths). The statistical significance of these results was high (p<0.0001).
In a secondary endpoint, Paxlovid reportedly reduced the risk of hospitalization or death for any cause by 88% compared to placebo in patients treated within five days of symptom onset; 0.8% of patients who received PAXLOVID were hospitalized or died through Day 28 following randomization (8/1039 hospitalized with no deaths), compared to 6.3% of patients who received placebo (66/1046 hospitalized with 12 subsequent deaths), with high statistical significance (p<0.0001).
Additionally, relative risk reduction in patients 65 years of age or older (one of the populations at highest risk for hospitalization or death) was 94%, and 1.1% of patients who received the treatment were hospitalized through Day 28 (1/94 hospitalized with no deaths), compared to 16.3% of patients who received placebo (16/98 hospitalized with 6 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. That figure is compared to 12 (1.2%) deaths in patients who received a placebo.
In a secondary endpoint in the trial, SARS-CoV-2 viral load at baseline and Day 5 were evaluated for 499 patients. After accounting for baseline viral load, geographic region, and serology status, Paxlovid reportedly reduced viral load by approximately tenfold, relative to placebo, indicating robust activity against SARS-CoV-2 and representing the strongest viral load reduction reported to date for an oral COVID-19 agent.
Treatment-emergent adverse events were comparable between the treatment (23%) and placebo (24%), most of which were mild in intensity. Fewer serious adverse events (1.6% compared to 6.6%) and discontinuation of study drug due to adverse events (2.1% vs. 4.2%) were observed in patients dosed with Paxlovid, compared to placebo, respectively.
Full study data are expected to be released later this month and submitted to a peer-reviewed publication.