Pfizer’s Abrysvo demonstrated a strong immune response and favorable safety profile in immunocompromised adults at high risk of severe RSV.
RT’s Three Key Takeaways:
- Phase 3 Results: Pfizer’s Abrysvo vaccine demonstrated a strong neutralizing response against RSV-A and RSV-B in immunocompromised adults, including those with non-small cell lung cancer, on hemodialysis, with autoimmune disorders, and solid organ transplant recipients, showing a favorable safety profile across all age groups.
- Addressing Unmet Needs: The study highlights the potential of Abrysvo to address the significant unmet need for RSV protection in immunocompromised adults aged 18 to 59, a group at high risk of severe RSV-related lower respiratory tract disease (LRTD), for which no vaccines are currently approved in the US.
- Regulatory and Market Progress: Pfizer plans to present these findings at an upcoming scientific conference, publish them in a peer-reviewed journal, and submit the data to regulatory agencies, building on previous approvals and expanding the potential market for Abrysvo, particularly with the recent approval of the ACT-O-VIAL system for vaccine reconstitution.
Pfizer Inc announced positive top-line safety and immunogenicity results from substudy B of the ongoing pivotal phase 3 clinical trial evaluating two doses of Abrysvo vaccine in immunocompromised adults aged 18 and older at risk of developing severe respiratory syncytial virus (RSV)-associated lower respiratory tract disease (LRTD).
Adults with immunocompromising conditions have an increased risk of developing RSV-LRTD. Substudy B of the MONeT (RSV I M munizati ON Study for Adul T s at Higher Risk of Severe Illness) trial was conducted to assess the safety and immunogenicity of two doses of Abrysvo, administered one month apart, in four groups of immunocompromised adults: those with non-small cell lung cancer, those on hemodialysis due to end-stage renal disease, those with autoimmune inflammatory disorder receiving active immunomodulator therapy, and solid organ transplant recipients.
Of the 203 adults enrolled in the substudy, approximately half were between the ages of 18 to 59, and approximately half were 60 years or older.
Abrysvo was well-tolerated during the trial, showing a safety profile consistent with findings from other studies of the vaccine. While the company evaluated two doses, a single 120 µg dose of Abrysvo generated a strong neutralizing response against both subtypes of RSV, RSV-A, and RSV-B, across all cohorts and age groups in the study.
Pfizer plans to share these findings at an upcoming scientific conference and publish them in a peer-reviewed scientific journal, as well as submit these data to the regulatory agencies for review.
“Immunocompromised adults, such as patients with cancer or autoimmune disorders, have a substantially increased risk of experiencing severe complications from RSV, yet there are currently no vaccines approved for those aged 18 to 59 in the US,” says Annaliesa Anderson, PhD, senior vice president and chief scientific officer of vaccine research and development at Pfizer, in a release. “We are encouraged by the positive top-line data from this study, which provide important evidence that Abrysvo has the potential to address a significant unmet need in this vulnerable population.”
Builds on Body of Evidence
These most recent data in immunocompromised adults build on the body of evidence supporting the profile of Abrysvo in high-risk adults. In June, at the meeting of the Advisory Committee on Immunization Practices (ACIP), Pfizer presented results from a cohort of adults aged 18-59 with certain chronic medical conditions.
In the double-blinded study, 681 adults aged 18 to 59 with chronic conditions were randomized 2:1 to receive a single dose of Abrysvo or placebo. Participants demonstrated RSV-A and RSV-B subgroup neutralizing responses non-inferior to the response seen in the phase 3 RENOIR study of Abrysvo, which previously demonstrated Abrysvo’s efficacy in a population of adults aged 60 or older.
These results support previous data presented at the ACIP showing high Abrysvo clinical effectiveness against lower respiratory tract disease among a population of adults age 60 years and older that included a substantial proportion of immunocompromised persons.
Approval of ACT-O-VIAL
Additionally, the US Food and Drug Administration has approved Pfizer’s supplemental Biologics License Application for the ACT-O-VIAL presentation of Abrysvo. This approval allows Pfizer to bring a new option to market alongside its existing needle-free reconstitution kits.
The ACT-O-VIAL System is a dual-component vial system that simplifies the reconstitution of Abrysvo within a single, compact device. Designed to support safety, workflow improvements, and storage efficiency, the system offers storage space savings, which may be appealing to retailers during peak vaccination seasons.
FDA Approvals for Abrysvo
In May 2023, the FDA approved Abrysvo for the prevention of LRTD caused by RSV in individuals 60 years of age or older. The Advisory Committee on Immunization Practices (ACIP) of the US Centers for Disease Control and Prevention recommends RSV vaccines as a single dose for all adults 75 and older and for adults 60 and older at increased risk of severe RSV disease.
In August 2023, the FDA approved Abrysvo for the prevention of LRTD and severe LRTD caused by RSV in infants from birth up to six months of age by active immunization of pregnant individuals at 32 through 36 weeks gestational age. This was followed in September 2023 with ACIP’s recommendation for maternal immunization to help protect newborns from RSV seasonally where the vaccine should be administered from September through January in most of the continental United States.
In addition to MONeT, Pfizer has initiated a clinical trial evaluating Abrysvo in children ages two to less than 18 years who are at higher risk for RSV disease.
