Nabi Biopharmaceuticals has initiated its US StaphVAX [Staphylococcus aureus Polysaccharide Conjugate Vaccine] immunogenicity study in orthopaedic surgery patients with implanted devices.

The study is a double- blinded, placebo-controlled trial that will evaluate a total of 120 patients undergoing orthopaedic surgery that involves the implantation of synthetic material (such as hip or knee replacement). Results from this study are expected to be available by the end of the third quarter of 2005.

The objective of this study is to evaluate safety and antibody levels in these patients over a six-month period. The company expects this study will demonstrate that after vaccination with StaphVAX, this large at-risk patient group can achieve antibody levels equal to or greater than the levels proven to be protective in immune-compromised end-stage renal disease (ESRD) patients. Patients undergoing orthopaedic surgery are at high risk of developing S. aureus bacteremia and subsequent infections because of the invasive nature of this surgery, the company release says.

"Staph aureus infections and their growing resistance to traditional antibiotics are serious public health issues, particularly for those patients undergoing orthopaedic surgeries," said Henrik Rasmussen, senior vice president of clinical research, medical and regulatory affairs and project management, Nabi Biopharmaceuticals. "By effectively immunizing patients at- risk against Staph aureus infections, StaphVAX could represent a completely new paradigm in addressing this growing, unmet medical problem. Each year more than 2.6 million people undergo orthopaedic implant surgery in the United States and an additional 800,000 hip and knee replacement surgeries are performed in Europe. These patients are all at an increased risk of being afflicted with a staph infection as a complication of this surgery," he added.

The company also announced that patient enrolment in a similarly designed immunogenicity study in cardiovascular surgery patients with implanted devices is accelerating, and results are now expected to be available by the end of the third quarter of 2005. This will be in sufficient time to support the filing of the StaphVAX Biologics License Application (BLA) in the United States before the end of 2005.

S. aureus bacteria are the most common cause of hospital-acquired infections and are becoming increasingly resistant to antibiotics, rendering these bacteria a potent cause of illness and death. The incidence of S. aureus infections, and in particular strains that are resistant to Methicillin, MRSA, is continuing to increase rapidly.