June 25, 2024

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Pfizer mRNA Flu Vaccine Reaches Phase 3 Trial Dual Primary Endpoints

Pfizer mRNA Flu Vaccine Reaches Phase 3 Trial Dual Primary Endpoints, Moderna Accelerates mRNA Flu Vaccine Launch



Pfizer mRNA Flu Vaccine Reaches Phase 3 Trial Dual Primary Endpoints, Moderna Accelerates mRNA Flu Vaccine Launch

On November 1, 2023, Pfizer announced in its third-quarter report that its investigational modFlu mRNA flu vaccine candidate has successfully achieved two major endpoints in its ongoing Phase 3 trial among individuals aged 18 to 64.

Preliminary analysis indicates that this mRNA candidate vaccine demonstrates non-inferiority and superiority compared to currently available flu vaccines.

modFlu (PF-07252220) is the first-generation mRNA vaccine developed by Pfizer and BioNTech for flu prevention.

In the trial, this mRNA candidate vaccine exhibited non-inferiority and superiority to currently available flu vaccines at the primary analysis point.

Effectiveness in the 18-64 age group was maintained through the trial endpoint analysis, demonstrating non-inferiority compared to the control vaccine.

The primary and season-end efficacy analysis considered both influenza A and B cases, although the vast majority of cases in this group and during the overall 2022/2023 flu season were of influenza A type.

Pfizer mRNA Flu Vaccine Reaches Phase 3 Trial Dual Primary Endpoints, Moderna Accelerates mRNA Flu Vaccine Launch

Pfizer’s layout in the field of respiratory vaccines.
Source: Reference[2]

However, regarding secondary immunogenicity efficacy endpoints, the vaccine only reached the secondary endpoint against influenza A strains, not influenza B strains.

In terms of safety, the flu mRNA candidate vaccine’s safety profile for the 18-64 age group is similar to standard flu vaccines. Pfizer expects to release Phase 3 trial data for adults aged 65 and older later this year.

Pfizer mRNA Flu Vaccine Reaches Phase 3 Trial Dual Primary Endpoints, Moderna Accelerates mRNA Flu Vaccine Launch

Summary of Phase 3 trial results of Pfizer’s mRNA influenza vaccine.
Source: Reference[2]

Leading the way: Moderna

It is worth mentioning that, like Pfizer, Moderna has been developing an mRNA flu vaccine, mRNA-1010. In the initial clinical trials, mRNA-1010 demonstrated superior seroconversion rates for influenza A strains H1N1 and H3N2 compared to existing vaccines. However, mRNA-1010 did not achieve non-inferiority for combating influenza B strains Yamagata and Victoria. After refining the vaccine formulation, Moderna’s clinical results announced in September this year showed that mRNA-1010 reached all major endpoints for all four virus strains (H1N1, H3N2, Yamagata, and Victoria). Compared to approved control vaccines, this vaccine showed higher geometric mean titers and seroconversion rates for all four virus strains.

Moderna presented the latest progress in its development pipeline, focusing on the new formulation of the mRNA-1010 flu vaccine at its annual R&D day event on September 13.

Moderna has disclosed updated mid-term data for mRNA-1010 in Phase 3 clinical trial P303 after refining the formulation, reaching all major endpoints for four seasonal flu virus strains. mRNA-1010 achieved higher hemagglutination inhibition (HAI) titers for all four subtypes A/H1N1, A/H3N2, B/Yamagata, and B/Victoria compared to the inactivated flu vaccine Fluarix.

In another Phase 1/2 clinical trial, mRNA-1010 achieved higher HAI titers for A/H1N1, A/H3N2, and B/Victoria when compared head-to-head with Sanofi’s Fluzone and comparable HAI titers for B/Yamagata. Although mRNA-1010 did not demonstrate ideal immunogenicity against influenza B in the first two Phase 3 clinical trials, Moderna resolved this issue through formulation optimization, achieving non-inferiority and superiority against influenza B strains as well.

Based on communications with regulatory agencies, Moderna anticipates that their mRNA flu vaccine could potentially be available as early as 2024 and is working to expedite the process.

The Disappearance of Influenza B Yamagata Strains

During the pandemic, the influenza B Yamagata lineage, one of the four major circulating influenza strains, disappeared from human influenza surveillance networks and had not been detected globally for three years.

On October 5, 2023, a vaccine and related biological products advisory committee (VRBPAC) composed of vaccine experts unanimously agreed to exclude the influenza B Yamagata lineage from future flu vaccines. The World Health Organization (WHO) had previously announced its agreement to remove the influenza B Yamagata lineage from the 2024 Southern Hemisphere flu vaccine formulation. Experts suggest that this change should not significantly impact the effectiveness of flu vaccines.

Pfizer mRNA Flu Vaccine Reaches Phase 3 Trial Dual Primary Endpoints, Moderna Accelerates mRNA Flu Vaccine Launch

References

[1] Pfizer Reports Third-Quarter 2023 Results. Retrieved October 31, 2023 from https://s28.q4cdn.com/781576035/files/doc_financials/2023/q3/Q3-2023-PFE-Earnings-Release.pdf

[2] Third Quarter 2023 Earnings Teleconference. Retrieved October 31, 2023 from https://s28.q4cdn.com/781576035/files/doc_financials/2023/q3/Q3-2023-Earnings-Charts-FINAL.pdf

(source:internet, reference only)


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