Streptococcus agalactiae bacteria, responsible for vaginal and urinary tract infections and infections in newborns, including meningitis and septicemia. Optical microscopy view.
Cavallini James | BSIP | Universal Image Group | Getty Images
Pfizer on Wednesday said it was experimental vaccine targeting the potentially deadly bacterial disease Group B Streptococci came back strong in the center of the stage clinical trial resultsa promising step as the drug inches toward potential approval.
Pfizer is one of several drugmakers racing to develop the world’s first injection targeting group B streptococcal disease, which is linked to nearly 150,000 infant deaths every year worldwide, especially in low-income countries.
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The Food and Drug Administration in September breakthrough therapy to Pfizer’s vaccine, which is intended to accelerate development and evaluation of the injection.
The single-dose injection of Pfizer generated antibodies that may provide babies with meaningful protection against the disease, the study said. facts released Wednesday of a phase two clinical trial.
The jab is administered to expectant mothers, who pass vaccine-induced antibodies to their fetuses. One of the company’s vaccines targeting respiratory syncytial virus also uses that maternal method of vaccination.
The encouraging results of Pfizer’s second phase offer hope that vaccinating mothers against the disease, also known as GBS, could help prevent thousands of cases in babies.
The results will also help the company plan its phase three clinical trials on the injection, which are typically required before the FDA approves a drug.
The Bill & Melinda Gates Foundation, which supported the phase two trial, provided an additional $100 million grant last year to Pfizer, which will fund late-stage trials and help facilitate delivery of injections to lower-income countries following potential approval.
GBS risk
GBS disease is caused by a common and mostly harmless bacteria that many adults carry in their bodies.
But an expectant mother can pass that bacteria on to a newborn during labor and delivery, which can cause serious infections during the baby’s first few weeks or months of life.
About 1 in 4 women carry GBS bacteria, according to the Centers for Disease Control and Prevention.
Babies with GBS infections may experience symptoms such as fever and difficulty breathing.
Some babies may experience invasive GBS infections, which cause more serious complications such as pneumonia, infections in the bloodstream and meningitis, or the inflammation of tissues around the brain and spinal cord.
There are 10 different GBS serotypes, meaning different variations of the bacteria that cause the disease. Pfizer’s vaccine targets six of the most prominent serotypes, which collectively represent 98% of GBS cases worldwide.
Trial results and safety
Pfizer’s trial followed 360 healthy pregnant individuals in South Africa. The mothers were randomly assigned to a single injection at three different dosage levels, with or without a specific adjuvant or a placebo.
The trial showed that the Pfizer injection generated robust antibodies against the six GBS serotypes in mothers. Those antibodies were “efficiently transferred” to infants in ratios between 0.4 and 1.3, depending on the dose.
That means some babies received only a fraction of their mother’s antibodies, while others received even higher antibody levels than their mothers had.
Pfizer said those levels of antibody transfer are associated with a reduced risk of GBS disease. That conclusion was based on a parallel natural history conducted in South Africa.
The safety profile for both mothers and babies appeared to be similar between the vaccine and placebo groups, according to the study results, suggesting that the injection was generally well tolerated during the phase two trial.
Reactions in mothers following vaccination were generally mild or moderate in nature and of short duration. Between 2% and 8% of participants who received the shot reported fever, compared with 5% in the placebo group, according to the results.
About 45% to 70% of pregnant individuals who received the vaccine experienced more side effects such as headaches and vomiting. But the placebo group was not much different, with more than 60% of expectant mothers experiencing these side effects.
About 62% to 75% of babies in the vaccine group and 74% of those in the placebo group experienced side effects, including upper respiratory infection. There were three infant deaths in the vaccine group and two in the placebo group.
The study authors determined that there were no side effects or infant deaths related to the vaccine.
The results come as Pfizer braces for a sequel drop in covid-related sales this year.
Pfizer also faces a patent cliff, or loss of market exclusivity, for several blockbuster drugs such as cancer drugs Xtandi and Ibrance. That is expected to be an additional blow to Pfizer’s annual revenue by 2030.
To counter a sharp sales decline, the company is shifting its focus to a new drug pipeline and M&A.
