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StaphVAX Immunogenicity Study Initiated in Orthopedic Surgery Patients
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 orthopedic surgery are at high risk of developing S. aureus bacteremia and subsequent infections because of the invasive nature of this surgery.
"Staph aureus infections and their growing resistance to traditional antibiotics are serious public health issues, particularly for those patients undergoing orthopedic surgeries," said Henrik Rasmussen, MD, Ph.D, 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 orthopedic 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."
The company also announced that patient enrollment 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.
About Staphylococcus aureus Infections
An estimated 12 million patients are at risk for developing a S. aureus infection each year in the United States. Within the country's 7,000 acute care hospitals, S. aureus is one of the three leading causes of hospital-based bloodstream infections and has a crude mortality rate of 25 percent. Patients at greatest risk are those who are immune compromised, those whose treatment requires an invasive surgical procedure, such as implanted prosthetic devices, and those with chronic illnesses such as ESRD patients on dialysis.
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.
Worldwide, it is estimated that more than 95 percent of patients with S. aureus infections no longer respond to first-line antibiotics, such as penicillin or ampicillin. In response, Methicillin became the standard of care for treating these infections. Recent data have shown dramatic increases in Methicillin-resistant S. aureus (MRSA) in most European countries, including an increase from 30 percent to 44 percent in the U.K. and an increase from 22 percent to 28 percent in Belgium. Recent data published in Clinical Infectious Diseases that was based on a comprehensive survey of 49 major hospitals in the United States found the rate of MRSA more than doubled over a seven-year period, from 22 percent in 1995 to 57 percent in 2002. The situation is even more dire in certain Asian countries, with rates of MRSA in Japan; Hong Kong and Taiwan reaching 72 percent, 74 percent and 61 percent, respectively.
StaphVAX (Staphylococcus aureus Polysaccharide Conjugate Vaccine) is an investigational vaccine designed to prevent S. aureus infections in at-risk patients. This novel application of Nabi Biopharmaceuticals' vaccine technology stimulates the patient's immune system to build antibodies to the most common forms of S. aureus infections without the development of resistance. In December of 2004, Nabi Biopharmaceuticals submitted a Marketing Authorization Application (MAA) to the European Agency for Evaluation of Medicinal Products (EMEA) under the Centralized Procedure for approval to market StaphVAX within the European Union. StaphVAX is currently in a confirmatory Phase III clinical trial in the United States. This double- blinded, placebo-controlled and randomized trial is being conducted in ESRD patients undergoing hemodialysis. The nearly 4,000-patient study is designed to demonstrate statistical significance with a clinical reduction of 50 percent or more in types 5 and 8 S. aureus infections. The company plans to file a Biologics License Application incorporating results from this Phase III trial and immunogenicity studies in other at-risk patient populations before the end of 2005.
Source: Nabi Biopharmaceuticals