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Favorable Nonclinical Safety Profile of RSVpreF Bivalent Vaccine in Rats and Rabbits
Jun Zhou1, Christopher J Bowman1, Vicki R Markiewicz1,2
1Drug Safety Research and Development, Pfizer Research & Development, Groton, CT 06340, USA.
Vaccines
|January 24, 2025
Summary
Pfizer's bivalent Respiratory Syncytial Virus prefusion F protein (RSVpreF) vaccine demonstrated good tolerability in nonclinical studies. The RSVpreF vaccine showed no adverse effects on reproductive or developmental health in animal models.
Area of Science:
- Vaccinology
- Immunology
- Toxicology
Background:
- Respiratory Syncytial Virus (RSV) is a major cause of infant mortality and hospitalization, and increases morbidity/mortality in older adults.
- Pfizer's Abrysvo® (RSVpreF) is a bivalent, unadjuvanted vaccine targeting RSV A and B subgroups.
- It's the sole RSV vaccine approved for maternal immunization and active immunization in adults aged 18-59 with high-risk conditions and those 60+.
Purpose of the Study:
- To assess the nonclinical safety of the RSVpreF bivalent vaccine.
- Evaluate potential reproductive and developmental toxicity.
- Support early clinical development of the RSVpreF vaccine.
Main Methods:
- Nonclinical safety studies included a repeat-dose toxicity (RDT) study in rats and a combined developmental and reproductive toxicity (DART) study in rabbits.
- RSVpreF vaccine, with or without aluminum hydroxide (Al(OH)3), was administered intramuscularly (IM) at twice the human dose.
- Study designs adhered to relevant regulatory guidelines.
Main Results:
- Local, reversible inflammatory responses at injection sites and draining lymph nodes were observed.
- No adverse effects on female fertility, embryo-fetal development, or postnatal survival/growth were noted in the DART study.
- Robust immune responses to both RSV A and B antigens were achieved, particularly with the Al(OH)3 formulation.
Conclusions:
- The RSVpreF vaccine demonstrated good local and systemic tolerability in nonclinical safety studies.
- No adverse effects on reproductive and developmental endpoints were identified.
- These findings support the vaccine's safety profile for its intended populations.
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