ADC Reviews

GBS Vaccine Receives FDA Breakthrough Therapy Designation


On September 7, Pfizer announced that its GBS vaccine candidate GBS6 (PF-06760805) has been granted breakthrough therapy designation by the FDA for the prevention of neonatal GBS infection by immunizing pregnant women.

The FDA’s designation is based primarily on an interim analysis of GBS6’s Phase II clinical trial (NCT03765073), which was designed to evaluate the safety and immunogenicity of GBS6 in healthy pregnant women aged 18 to 40 years. The study is still ongoing, and specific results will be disclosed when the trial is completed.

Group B Streptococcus is Gram-positive, named after the chain-like arrangement of microscopic observations. It is commonly found in the intestinal tract and is the biggest killer of neonatal sepsis. About 1/4 of healthy adult women carry group B streptococcus in the genital tract, and most of the carriers are asymptomatic. Group B streptococcus infects neonates mainly through vertical transmission during birth or horizontal transmission after birth.

Thirty percent of GBS-infected neonatal sepsis survivors have neurological sequelae, such as hearing or vision impairment, learning and movement disorders, or cerebral palsy. The infection mode is divided into two types: “early onset” and “late onset”: the former is the onset within a week after birth, and is mainly “vertical infection”, which is infected in the mother’s uterus as the main route of infection. %; the latter occurs in the postpartum week, and is often caused by “horizontal infection” caused by contact with unclean hands, which is less common.

GBS (Group B Streptococcus) normally colonizes the vagina and intestines, and belongs to opportunistic pathogens. GBS infection can cause serious harm to the health of both mothers and infants. Infection of pregnant women with GBS can lead to chorioamnionitis, premature rupture of membranes, and then induce premature birth and stillbirth. GBS can lead to neonatal pneumonia, sepsis, and purulent meningitis after GBS is transmitted to neonates through amniotic fluid or through the birth canal during delivery. According to statistics, there are about 410,000 GBS cases worldwide each year, and at least 147,000 stillbirths and neonatal deaths.

GBS6 is an investigational maternal vaccine that provides protection against the 6 major GBS serotypes (covering 98% of cases). After pregnant women receive the vaccine, antibodies can be transferred across the placenta to the fetus to protect the newborn from GBS. Previously, in March 2017, GBS6 was granted Fast Track status by the FDA. In April 2022, the vaccine was granted priority drug status by the European Union.