Pfizer Files FDA NDA for Paxlovid

Pfizer announced today they had filed their Food and Drug Administration (FDA) new drug application (NDA) for Paxlovid (nirmatrelvir [PF-07321332] tablets and ritonavir tablets) for patients who are at high risk for progression to severe illness from COVID-19.

“Data from our clinical development program, coupled with the more than 1.7 million patients around the world who have been prescribed our oral treatment to date, reinforce Paxlovid as an important treatment option for mild-to-moderate COVID-19 in patients at greater risk of progression to severe symptoms, regardless of vaccination status,” Pfizer CEO Albert Bourla, said.

Pfizer's EPIC-HR study, published in the New England Journal of Medicine, included 2246 symptomatic, unvaccinated adults with confirmed COVID-19 who were at high risk for developing severe disease due to characterizations such as old age, smoking, cardiovascular disease, diabetes, obesity or cancer. Participants were enrolled at 343 sites around the world between July 16 and Dec. 9, 2021.

The participants were randomized into 2 groups, with 1120 receiving Paxlovid (300 mg of nirmatrelvir plus 100 mg of ritonavir) and 1126 receiving a placebo every 12 hours for five days. The results showed that Paxlovid reduced the risk of hospitalization or death from any cause by 89% for those who began treatment within three days of symptom onset and by 88% among those who began treatment within five days. Results were consistent across all subgroups.

Final results from the study showed an 86% reduction in relative risk of hospitalizations or death from any cause; no deaths were observed in patients treated with Paxlovid, compared to 15 deaths observed with placebo.

In positioning this therapy in the market, Pfizer pointed to the Centers for Disease Control and Prevention (CDC) statistic that 50-60% of the US population is estimated to have 1 or more risk factors for progressing to severe COVID-19. These risk factors include: people ages 65 and older, obesity, diabetes, hypertension, smoking, physical inactivity, chronic kidney or liver disease, and immunocompromised conditions such as cancer, among others.

“As the COVID-19 pandemic continues to evolve and be highly unpredictable, we must remain vigilant in protecting those who are at greatest risk of getting very sick from COVID-19, as they remain vulnerable to potential hospitalization or even death,” Bourla stated.

A few weeks ago, public reports stated a rebound of symptoms of COVID-19 and retesting positive for SARS-CoV-2 after testing negative with Paxlovid. This prompted a health advisory from the CDC, which characterized the rebound as typically short-lived (median 3 days), occurring 2 to 8 days after putative response to treatment, and not requiring additional anti-COVID-19 treatment.

As this filing is just being reported, no timeline has been established for the review of the NDA.