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The press release from Pfizer provides additional phase 2/3 study results confirming robust efficacy of their COVID-19 oral antiviral treatment candidate, PAXLOVID™.
Prof Penny Ward, Independent Pharmaceutical Physician, and Visiting Professor in Pharmaceutical Medicine at King’s College London, said:
“Good news yesterday came in a press release from Pfizer. They have confirmed in a press release that, as predicted, their protease inhibitor retains an in vitro antiviral effect vs the omicron variant and therefore the continued relevance of the clinical data announced from trials conducted during waves of illness caused by other strains.
“The release also announced the results from the completed phase III study in unvaccinated higher risk patients (EPIC-HR) with the final effectiveness of treatment with Paxlovid within the first 5 days of illness reducing hospitalisations and deaths from 6.5% in the placebo group to 0.7% among Paxlovid recipients, a relative effectiveness in preventing severe illness/death of 88%. Treatment within the first 3 days was slightly more effective, reducing severe disease/death by almost 90%. These results confirm the findings of the prior interim analysis and reiterate the high level of effectiveness of this agent, potentially conferring an additional approach to the management of covid at a time when vaccine effectiveness is under challenge.
“In this respect, the interim analysis from a second study, (EPIC-SR) which included patients at ‘standard risk’ (i.e. at low risk of hospitalisation/death) as well as vaccinated patients with or more risk factors for progression to severe disease were also encouraging. Although the primary endpoint (time to self reported sustained relief of all symptoms for at least 4 days) was missed, in a secondary analysis, treatment with Paxlovid treatment reduced hospitalisations from 2.4% in the placebo group to 0.7% in the Paxlovid group, a relative reduction of 70% in severe disease. These data suggests that the product could be helpful in a highly vaccinated population and reduce the strain of additional admissions within an overloaded health service. If we take the EPIC-SR rates, the number needed to treat (NNT) to prevent one hospitalisation is ~56 whereas in EPIC-HR, the NNT is ~17, reflecting the significantly greater risk of hospitalisation in high risk unvaccinated patients.
“The press release does not provide detailed information on the side effect profile of this drug, an important concern for future prescribers, and the need to use ritonavir as a kinetic ‘booster’ for the protease inhibitor increases the risk of drug interactions with medicines which older, frailer patients may need to take for other medical conditions. It will be very helpful to see a full report of this data which hopefully will become available soon as Pfizer has requested early use authorisation in the USA.
“The UK has pre-ordered ~230,000 courses of this product pending MHRA approval for use: with an omicron wave looming, wise choices as to NHS deployment of this and other antiviral medicines with retained activity against the new strain will be needed if we are to use all the tools at our disposal to prevent even greater service overload.”
All our previous output on this subject can be seen at this weblink:
www.sciencemediacentre.org/tag/covid-19
Declared interests
Prof Penny Ward: “I am semi-retired, but I am owner/Director of PWG Consulting (Biopharma) Ltd a consulting firm advising companies on drug and device development. Between December 2016 and July 2019 I served as Chief Medical Officer of Virion Biotherapeutics Ltd, a company developing antiviral treatments for respiratory viral diseases. Previous employee of Roche, makers of tocilizumab (anti IL6 antibody) and CMO of Novimmune, makers of empalumab (anti IFN gamma antibody).”