Pfizer promotes RSV vaccine benefits for immunocompromised adults

Pfizer is poised to engage with the FDA concerning the potential approval of its respiratory syncytial virus (RSV) vaccine, Abrysvo, for immunocompromised individuals. This step is part of Pfizer's broader strategy to extend the reach of its RSV offering amidst a competitive landscape.

Pfizer announced that Abrysvo had shown robust efficacy in adults of varying ages with compromised immune systems. The phase 3 MONeT study demonstrated that a single dose of the vaccine generated strong neutralizing antibodies against both RSV subtypes across all tested groups, even though the study initially assessed two doses administered one month apart. Pfizer plans to submit these findings to regulatory authorities for review and will present the detailed results at an upcoming scientific conference.

Dr. Annaliesa Anderson, Pfizer’s chief scientific officer for vaccine research and development, highlighted the heightened risk that immunocompromised adults, such as those with cancer or autoimmune disorders, face regarding severe RSV complications. Currently, no approved RSV vaccines exist for individuals aged 18 to 59 in the U.S., making this development particularly significant.

Previously, Abrysvo received FDA approval as a single-dose injection aimed at preventing lower respiratory tract disease caused by RSV in individuals 60 years and older, as well as in infants via maternal vaccination. The latest findings on immune response come from 203 adults in four cohorts of the MONeT trial, including those with non-small cell lung cancer, end-stage kidney disease, autoimmune disease, and solid organ transplant recipients. Notably, around half of the participants were younger than 60, a group for which Abrysvo is not yet approved.

Earlier results from another part of the trial, involving 681 adults below 60 with chronic conditions, showed similar neutralizing antibody responses to those observed in the phase 3 RENOIR study. This earlier study was crucial for Abrysvo's initial FDA approval for adults aged 60 and older.

Apart from Abrysvo, other RSV vaccines are also making their mark. GSK’s Arexvy has been approved for adults aged 60 and older, as well as those aged 50 to 59 at increased risk of severe illness. Similarly, Moderna’s mRESVIA was approved for the 60-and-above age group in May. Despite these approvals, the Centers for Disease Control and Prevention’s Advisory Committee on Immunization Practices (ACIP) in June only endorsed RSV immunization for adults 75 and older, and for high-risk individuals aged 60 to 74. This restricted recommendation has led GSK to revise its 2024 vaccine sales projection downward. Meanwhile, Pfizer remains optimistic about Abrysvo’s performance for the year, as stated by CEO Albert Bourla.

Many healthcare providers and pharmacies favor the convenience of a single vaccine for both adult and maternal vaccinations, a feature unique to Abrysvo, according to Aamir Malik, Pfizer’s chief U.S. commercial officer. Despite the ACIP's limited recommendations, Malik noted that the guidance provides clarity and strengthens the vaccination directive for eligible individuals. Previously, RSV vaccination was recommended for all adults aged 60 and older, contingent upon a healthcare provider’s consultation.

Looking ahead to the 2024-25 RSV season, GSK claims market leadership based on existing contracts. Malik indicated that Pfizer has also strengthened its contracting position, although he did not provide specific details. Moderna's mRESVIA is currently perceived as the weakest among the three leading RSV vaccines, and GSK's Arexvy seems unlikely to enter the maternal vaccination market.

Both GSK and Pfizer are actively bolstering their cases for their respective RSV vaccines. Pfizer has recently submitted applications for Abrysvo for adults aged 18 to 59 in both the U.S. and Europe. Concurrently, GSK has initiated a phase 3b trial for Arexvy in adults aged 18 to 49 at increased risk of RSV disease, with a phase 2b study in lung and kidney transplant recipients aged 50 and above expected to yield results this year. Additionally, GSK is conducting extensive clinical programs to evaluate the co-administration of Arexvy with other vaccines, including those for flu, pneumococcal disease, and shingles.

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