Nabi Biopharmaceuticals announced the start of a clinical trial to evaluate the immunogenicity of StaphVAX (Staphylococcus aureus polysaccharide conjugate vaccine) using a newly manufactured lot of vaccine also intended for use in a planned confirmatory Phase III trial later this year.

StaphVAX is an investigational vaccine containing capsular polysaccharides from types 5 and 8 S. aureus linked to carrier protein. Types 5 and 8 S. aureus account for approximately 85% of all S. aureus infections. The immunogenicity trial is an open-label, single-dose study in 40 healthy volunteers to evaluate the antibody response to StaphVAX through 28 days post-vaccination. Enrollment is expected to be completed during the first week in July.

"The immunogenicity trial is a short, but important next step in the development of StaphVAX," said Henrik S. Rasmussen, senior vice president, clinical, medical and regulatory affairs. "We want to make certain that the StaphVAX antibody levels achieved with this clinical lot of vaccine are essentially the same as those levels that were generated from vaccine produced in our research facility and used in the first StaphVAX Phase III trial. We are very excited about StaphVAX as there clearly is a significant and growing medical need for this product. In our first Phase III clinical trial in 1800 patients with end-stage renal disease, we saw a solid indication of StaphVAX efficacy and safety through ten months post-vaccination." Dr. Rasmussen continued, "The confirmatory Phase III trial will be conducted in the same patient population. The primary endpoint will be statistically significant reduction of bacteremia caused by types 5 and 8 S. aureus through 8 months post-vaccination, the peak efficacy point in the first Phase III trial."

"Having StaphVAX back in the clinic is a very important step in the continued development of Nabi Biopharmaceuticals," said David J. Gury, chairman and chief executive officer. "With the completion of the immunogenicity study, we will begin the Phase III confirmatory trial in the second half of this year. This will be the final step in the clinical development of this first of a kind innovative product."

According to the U.S. Centers for Disease Control and Prevention (CDC), more than two million patients in the U.S. each year contract an infection as a result of exposure while receiving healthcare in a hospital. S. aureus is among the most common causes of these hospital-acquired infections and is reportedly associated with a death rate of 10 percent to 30 percent because of its capacity to cause serious complications and its resistance to many different antibiotics. S. aureus can spread from the blood (bacteremia), to the bones (osteomyelitis), or the inner lining of the heart and its valves (endocarditis), or cause abscesses in internal organs such as the lungs and kidneys. People most at risk for these infections are surgical patients, trauma or burn victims, newborns whose immune systems are not yet developed, and patients with such chronic illnesses as diabetes, cancer, or lung or kidney diseases. Patients with end-stage renal disease on hemodialysis represent a particular high risk group due to the need for access to their blood system several times a week. In addition, people whose immune systems are suppressed due to disease, chemotherapy or radiation therapy are also more susceptible to these bacterial infections.