Pfizer’s Potential GBS Vaccines Swipes Up the FDA’s Breakthrough Therapy Designation

On September 7, the United States Food and Drug Administration (FDA) granted Pfizer’s investigational Group B Streptococcus (GBS) vaccine candidate its Breakthrough Therapy Designation. Known as GBS6 or PF-06760805, the vaccine prevents the invasive GBS disease in newborns and young infants through immunization of their mothers during pregnancy. The FDA based its decision on findings from an ongoing Phase 2 clinical trial. 

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The Risk of GBS and Current Treatments

GBS is a bacteria found in the intestines or lower genital tract. In adults, they are typically harmless. However, in newborns, this bacteria causes a serious illness. 

Around 25% of pregnant women have GBS but are unaware as it does not cause any symptoms. The infection passes to the newborn upon vaginal birth. Though most babies with GBS don’t become sick, 75% of those who do become ill within the first week of life. Signs of infection become apparent only hours after birth. Symptoms of the infection include fever, difficulty feeding, irritability, breathing difficulties, and a lack of energy. About 4% of newborns who develop GBS die from the disease.

Current methods of GBS prevention include the administration of antibiotics during labor. These antibiotics are beta-lactams and include penicillin and ampicillin. According to an example from the Center for Disease Control (CDC), a mother who received antibiotics had a 1 in 4000 chance of their baby developing GBS, whereas a mother who didn’t have a 1 in 200 chance. However, doctors can only administer these antibiotics during labor as the bacteria grows back too quickly.

Another developing prevention is Pfizer’s vaccine. GBS6 offers protection against the six most prominent GBS serotypes, accounting for 98% of the disease worldwide. Though currently under evaluation in a Phase 2 Clinical Trial, the FDA granted the vaccine its Breakthrough Therapy Designation.

The Clinical Trial and the FDA’s Designation 

Researchers are studying the safety and efficacy of the GBS6 vaccine in an ongoing Phase 2 Clinical Trial. Though having yet to conclude, the subjects are around 586 healthy pregnant women between 18 and 40.

However, an interim analysis of the study swayed the FDA’s decision to grant the vaccine its Breakthrough Therapy Designation. This designation’s intent is to expedite the development and review of drugs treating serious conditions. This decision aligns with the FDA’s March 2017 decision to grant GBS6 Fast Track status.

On the designation, Annaliesa Anderson, Ph.D., Senior Vice President and Head of Vaccine Research & Development at Pfizer, said, “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.”

Currently, the study’s completion date is January 8, 2024. With the accolades already accumulated for the vaccine, the turnaround time for a Phase 3 trial will likely be swift. 

Author

Max Heirich