Pfizer Inc. announced that its respiratory syncytial virus (RSV) vaccine candidate, PF-06928316 or RSVpreF, received Breakthrough Therapy Designation from the U.S. Food and Drug Administration (FDA) for the prevention of lower respiratory tract disease caused by RSV in individuals 60 years of age or older.
The FDA decision is primarily informed by the positive results of a proof-of-concept, Phase 2a study evaluating the safety, immunogenicity, and efficacy of a single dose of 120µg RSVpreF in a human viral challenge model in healthy adults 18 to 50 years of age.
“Today’s decision is a significant step forward in our efforts to help protect vulnerable populations, particularly older adults, against certain potentially serious respiratory illnesses, including RSV,” said Kathrin U. Jansen, Ph.D., Senior Vice President and Head of Vaccine Research & Development at Pfizer Inc. “The clinical and economic burden of RSV represents a critical need, and we look forward to our ongoing dialogue with the FDA to accelerate the development of our RSV vaccine candidate.”
In September 2021, Pfizer announced the initiation of RENOIR (RSV vaccine Efficacy study iN Older adults Immunized against RSV disease), a Phase 3 clinical trial (NCT05035212) evaluating the efficacy, immunogenicity, and safety of a single dose of RSVpreF, in adults ages 60 years or older. This study remains ongoing.
The FDA’s Breakthrough Therapy Designation is designed to expedite the development and review of drugs and vaccines that are intended to treat or prevent serious conditions and preliminary clinical evidence indicates that the drug or vaccine may demonstrate substantial improvement over available therapy on a clinically significant endpoint(s).1
Burden of RSV
RSV is a disease for which there are currently no prophylactic, therapeutic, or vaccine options for older adults and the medical community is limited to offering only supportive care for adults with the illness.
Pfizer’s investigational RSV vaccine candidate builds on foundational basic science discoveries including those made at the National Institutes of Health (NIH), which detailed the crystal structure of prefusion F, a key form of the viral fusion protein (F) that RSV uses to attack human cells. The NIH research showed that antibodies specific to the prefusion form were highly effective at blocking virus infection, suggesting a prefusion F-based vaccine may confer optimal protection against RSV. After this important discovery, Pfizer tested numerous versions of the viral protein, and identified those that elicited a strong anti-viral immune response in pre-clinical evaluation. The vaccine candidate is composed of two preF proteins selected to optimize protection against RSV A and B.
Earlier this month, Pfizer announced RSVpreF received Breakthrough Therapy Designation from the U.S. Food and Drug Administration (FDA) for the prevention of RSV-associated lower respiratory tract disease in infants from birth up to six months of age by active immunization of pregnant women. The FDA designation was informed by the results of the Phase 2b proof-of-concept study of RSVpreF (NCT04032093), which evaluated the safety, tolerability and immunogenicity of RSVpreF in vaccinated pregnant women ages 18 through 49 and their infants. This followed the FDA’s November 2018 decision to grant Fast Track status to RSVpreF.
In June 2020, Pfizer announced the initiation of a multicenter, international Phase 3 clinical trial (NCT04424316) evaluating the efficacy and safety of RSVpreF when administered to pregnant women to help protect their babies from RSV after birth. This study remains ongoing.
1 U.S. Food and Drug Administration (FDA). Breakthrough Therapy. https://www.fda.gov/forpatients/approvals/fast/ucm405397.htm. Updated January 4, 2018. Accessed February 10, 2022.
2 Centers for Disease Control and Prevention. Respiratory Syncytial Virus Infection (RSV). https://www.cdc.gov/rsv/index.html. Updated December 18, 2020. Accessed February 22, 2022.
3 Centers for Disease Control and Prevention. Disease or Condition of the Week – Respiratory Syncytial Virus Infection (RSV). https://www.cdc.gov/dotw/rsv/index.html. Updated September 14, 2021. Accessed February 22, 2022.
4 Centers for Disease Control and Prevention. RSV Transmission. https://www.cdc.gov/rsv/about/transmission.html. Updated December 18, 2020. Accessed February 22, 2022.
5 Centers for Disease Control and Prevention. Respiratory Syncytial Virus Infection (RSV) – Older Adults are at High Risk for Severe RSV Infection Fact Sheet. https://www.cdc.gov/rsv/factsheet-older-adults.pdf. Accessed February 10, 2022.
6 Centers for Disease Control and Prevention. RSV in Infants and Young Children. https://www.cdc.gov/rsv/high-risk/infants-young-children.html. Updated December 18, 2020. Accessed February 22, 2022.
7 Falsey AR, et al. Respiratory Syncytial Virus Infection in Elderly and High-Risk Adults. N Engl J Med 2005; 352:1749-1759. DOI: 10.1056/NEJMoa043951
8 Hall CB, et al. The Burden of Respiratory Syncytial Virus Infection in Young Children. N Engl J Med. 2009; 360:588-598. DOI: 10.1056/NEJMoa0804877
9 Rha B, et al. Respiratory Syncytial Virus-Associated Hospitalizations Among Young Children: 2015-2016 Pediatrics. 2020 Jul;146(1):e20193611. doi: 10.1542/peds.2019-3611. Epub 2020 Jun 16.