Pfizer Announces Positive Top-Line Data for Abrysvo Immunization in Adults Aged 18 to 59 Years

Biscaldi,Lauren;

Pfizer Announces Positive Top-Line Data for Abrysvo Immunization in Adults Aged 18 to 59 Years

April 9, 2024

By Lauren Biscaldi, MS, Managing Editor

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Drug Topics JournalDrug Topics May 2024

Volume 168

Issue 04

Abrysvo is currently approved to treat RSV-associated lower respiratory tract disease in adults aged 60 years and older, and in infants through the immunization of pregnant individuals.

Pfizer has announced positive top-line immunogenicity and safety results from the ongoing phase 3 MONET clinical trial (NCT05842967) examining the efficacy of a single dose of the company’s respiratory syncytial virus (RSV) vaccine, Abrysvo, in adults aged 18 to 59 years at risk of developing severe RSV-associated lower respiratory tract disease.¹

Abrysvo is FDA approved for the prevention of RSV-associated lower respiratory tract disease in adults aged 60 years and older,² as well as for the prevention of lower respiratory tract disease and severe lower respiratory tract disease in infants through the immunization of pregnant individuals between 32 and 36 weeks gestational age.³ The company also recently released positive top-line data regarding the efficacy of Abrysvo through a second full RSV season in adults aged 60 years and older.⁴

RSV is a leading cause of respiratory illness. | Image credt: freshidea - stock.adobe.com

Although young children and older adults are at a higher risk for severe RSV, adults living with certain chronic conditions, such as asthma, diabetes, and chronic obstructive pulmonary disease, may also be at an increased risk of developing—and being hospitalized for—RSV-associated lower respiratory tract disease. According to data published in Infectious Diseases and Therapy, 9.5% of adults aged 18 to 49 have a chronic condition increasing their RSV risk; this number increases to 24.3% in adults aged 50 to 64 years.⁵ Despite this, there is no RSV vaccine currently approved for use in individuals aged 18 to 59 years.

The phase 3 MONET trial includes 2 sub-studies that evaluated safety, tolerability, and immunogenicity of Abrysvo in adults at higher risk for RSV-associated disease. In Substudy A, researchers evaluated vaccine use in adults with certain chronic medical conditions; Substudy B focused on immunocompromised adults.

Data show that the MONET study met its co-primary immunogenicity endpoints, as well as its primary safety endpoint. Both RSV-A and RSV-B subgroup neutralizing responses were noninferior to those seen in the phase 3 RENOIR clinical trial (NCT05035212) and the study that was used for initial FDA approval of the vaccine.

MONET study participants also achieved “at least a 4-fold increase in serum neutralizing titers for RSV-A and RSV-B” in the 1 month period after Abrysvo administration compared with pre-vaccination. The vaccine was well-tolerated among study participants, and safety findings were consistent with previous studies of Abrysvo across other populations.

Of note regarding the study population, Pfizer announced that the company had met its diversity recruitment goals for the MONET clinical trial, with a study population that “mirror[ed] the diverse US population and had a balanced representation across underlying medical conditions.”

According to the press release, the company will be submitting these data to regulatory agencies to request an age group expansion from the current indication to include adults aged 18 years and older. Findings will be published in a scientific journal, and will be shared at upcoming scientific meetings.

RSV is a common cause of respiratory illnesses and can cause severe illness in young children, older adults, and those with certain underlying chronic medical conditions. RSV infections represent approximately 60,000 to 160,000 hospitalizations and 6,000 to 13,000 deaths each year in the United States.

Pfizer has also initiated a clinical trial to evaluate Abrysvo in children aged 2 to younger than 18 years at higher risk for RSV.

READ MORE: Respiratory Resource Center