Pfizer Inc. today announced that its investigational Group B Streptococcus (GBS) vaccine candidate, GBS6 or PF-06760805, received Breakthrough Therapy Designation from the U.S. Food and Drug Administration (FDA) for the prevention of invasive GBS disease due to the vaccine serotypes in newborns and young infants by active immunization of their mothers during pregnancy.

The FDA decision is informed by the interim analysis of a placebo-controlled Phase 2 study (NCT03765073), evaluating the safety and immunogenicity of GBS6 in healthy pregnant women aged 18 to 40 years, who were vaccinated during the second or early third trimester of pregnancy. The study remains ongoing, and Pfizer will publish outcomes from this clinical trial when it is completed.

"GBS infections can have a devastating effect on newborns and their families. While prenatal screening and antibiotics during childbirth help provide protection against GBS in developed countries, this approach is not fully protective in the first week of life; presents multiple challenges in low- and middle-income countries; and has not been shown effective in preventing disease globally in infants beyond the first week of life and through the vulnerable first three months of life," said Annaliesa Anderson, Ph.D., Senior Vice President and Head of Vaccine Research & Development, Pfizer. "If approved for pregnant women, GBS6 could help protect newborns from the serious illnesses caused by this disease like meningitis, pneumonia, and sepsis - fulfilling a critical global public health need. We are encouraged by today’s decision and look forward to discussing GBS6 with the FDA and other regulatory agencies to potentially reduce neonatal deaths and positively impact the existing global disease burden of GBS."

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) This decision follows the FDA's March 2017 decision to grant Fast Track status to GBS6. Fast Track status is a process designed to facilitate the development and expedite the review of new drugs and vaccines intended to treat or prevent serious conditions and address an unmet medical need.(2)

About GBS6

Hexavalent anti capsular polysaccharide (CPS) / cross reactive material 197 glycoconjugate (GBS6) is an investigational maternal vaccine being developed to help prevent invasive Group B Streptococcus (GBS) in newborns. GBS6 is designed to offer protection against the six most prominent GBS serotypes, which account for 98% of disease worldwide.(3) It is being evaluated in an ongoing Phase 2, placebo-controlled study in pregnant women and their infants in South Africa, U.K., and the U.S. and is assessing the safety and immunogenicity of a single dose administered by intramuscular injection during the second or early third trimester of pregnancy to prevent disease in infants. Pfizer is pursuing a clinical development strategy in high-, middle- and low-income countries with the intent to make a successfully developed vaccine available globally as quickly as possible.

In April 2022, GBS6 was granted PRIME designation by the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP). This designation provides enhanced support for the development of medicines that target an unmet medical need.(4)

In 2016, Pfizer received a grant from the Bill & Melinda Gates Foundation, which supported the ongoing Phase 2 clinical trial of GBS6 as well as a parallel non-interventional natural history study.

About Group B Streptococcus (GBS)

Group B Streptococcus (GBS) is a common bacterium that can cause potentially devastating diseases in infants, including sepsis, pneumonia and meningitis, during the first three months of life. About one in four pregnant women carry GBS bacteria in their body and may pass it along to their baby during or prior to birth.(5) Annually, there are an estimated 410,000 GBS cases worldwide, which cause at least 147,000 stillbirths and infant deaths each year.(6)

About maternal immunization

During pregnancy, antibodies - special disease-fighting proteins - are actively transferred from the mother’s blood across the placenta and to the fetus. This natural process is known as transplacental antibody transfer. Vaccines given to pregnant women (maternal immunization) that are intended to prevent illness in young infants rely on this process of transplacental antibody transfer. When a pregnant woman is vaccinated, her immune response produces vaccine-specific antibodies, which can then be transferred to the fetus.(7) This protection from the mother is called "maternal immunity" and is critical for helping infants fight off potential infections during the most vulnerable first months of life.