Pfizer has said its oral COVID-19 antiviral, nirmatrelvir-ritonavir (Paxlovid), reduced the risk of hospitalisation or death by 89% if taken within three days of symptoms and by 88% (within five days), in a final analysis of its phase II/III trial, and that it may still protect against Omicron.
Final data available from all high-risk patients enrolled in EPIC-HR study (n= 2,246) confirmed prior results of interim analysis showing Paxlovid (nirmatrelvir tablets and ritonavir tablets) reduced risk of hospitalisation or death by 89% (within three days of symptom onset) and 88% (within five days of symptom onset) compared to placebo; no deaths compared to placebo in non-hospitalised, high-risk adults with COVID-19
The above data have been shared with the US Food and Drug Administration (FDA) as part of an ongoing rolling submission for Emergency Use Authorisation (EUA)
Separately, interim analyses of an ongoing second study in standard-risk adults (EPIC-SR) showed a 70% reduction in hospitalisation and no deaths in the treated population, compared to placebo, in the secondary endpoint; the novel primary endpoint of self-reported, sustained alleviation of all symptoms for four consecutive days, as compared to placebo, was not met. The study continues
An approximate 10-fold decrease in viral load at Day 5, relative to placebo, was observed in both EPIC-HR and EPIC-SR, indicating robust activity against SARS-CoV-2 and representing the strongest viral load reduction reported to date for a COVID-19 oral antiviral agent
Recent in vitro data confirm that nirmatrelvir is a potent inhibitor of the Omicron 3CL protease, which, combined with existing in vitro antiviral and protease inhibition data from other Variants of Concern (VoC) including Delta, indicates that Paxlovid will retain robust antiviral activity against current VoCs as well as other coronaviruses
Full study data are expected to be released later this month, and submitted to a peer-reviewed publication.
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