Pfizer begins phase 2b study of Staphylococcus aureus vaccine in adults undergoing spinal fusion surgery

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Pfizer has announced enrolment of the first patient in a phase 2b clinical trial of its investigational Staphylococcus aureus (S aureus) multi-antigen vaccine in adults undergoing elective spinal fusion surgery. The purpose of the study, named STRIVE (Staphylococcus aureus surgical inpatient vaccine efficacy), is to evaluate the safety and efficacy of the vaccine to determine if it prevents postoperative invasive S aureus infections in patients undergoing elective spinal surgery.

Surgical site infections (SSIs) are a significant and growing concern. SSIs caused by S aureus account for approximately 20% of all those in the USA, and are associated with an estimated annual treatment cost of US$12.3bn. Patients who suffer such infections due to antibiotic resistant (MRSA) or antibiotic sensitive (MSSA) S aureus have worse clinical outcomes, including increased mortality in comparison with non-infected patients.

“To date, there is no licensed vaccine available to prevent invasive S aureus disease,” said Kathrin Jansen, senior vice president and chief scientific officer of Vaccine Research and Development for Pfizer. “We believe results from this study, if positive, will bring us closer to a potential preventive measure for this challenging disease that is associated with considerable morbidity and mortality.”

The primary outcome of the study, with an estimated enrolment of 2,600 subjects, will measure the number of subjects in each treatment group with postoperative S aureus blood stream infections and/or deep incisional or organ/space surgical site infections occurring within 90 days after elective posterior instrumented lumbar spinal fusion. Secondary outcomes will also measure postoperative S aureus blood stream infections and/or deep incisional or organ/space surgical site infections occurring within 180 days after surgery, and postoperative S aureus surgical site infections occurring within 90 and 180 days after elective posterior instrumented lumbar spinal fusion. The estimated completion date of the study is in 2017.