Nabi Biopharmaceuticals Continues to Make Important Progress with StaphVAX(R) Development Program

ROCKVILLE, Md. -- Nabi Biopharmaceuticals announced that the company's StaphVAX(R) (Staphylococcus aureus Polysaccharide Conjugate Vaccine) continues to be on track towards achieving two important development milestones: First, filing its Marketing Authorization Application (MAA) in the European Union by end of 2004 and second, filing its Biologics License Application (BLA) in the United States by end of 2005. The company is rapidly advancing its confirmatory phase III trial of StaphVAX for the prevention of S. aureus bacteremia (bloodstream infections) to support this filing. After a blinded assessment of the overall S. aureus bacteremia event rates in this trial, the company reported that the infection rate thus far is consistent with the assumptions used in the design of the study.

"We continue to make excellent progress with our StaphVAX development program. After completing production of the vaccine consistency lots ahead of schedule, the preparation of the manufacturing section of our MAA for registration in Europe is on track and the MAA is expected to be filed before the end of this year," said Henrik S. Rasmussen, MD, PhD, senior vice president, clinical, medical and regulatory affairs, Nabi Biopharmaceuticals. "In addition, we have been carefully monitoring the infection event rate in our confirmatory phase III trial and based on our analysis, we are at virtually the same overall event rate in this trial as we were in the first StaphVAX trial. This is very reassuring and indicates to us that there has not been a change in overall S. aureus infection rates in end-stage renal disease patients between the first trial and this confirmatory study."

After a blinded assessment of the overall S. aureus bacteremia event rates in this ongoing confirmatory phase III, double-blinded trial, the company reported that the infection rate in this study is consistent with that found at the same point in the company's first phase III trial. Specifically, the primary S. aureus infection rate in this trial is 3.1 percent, which is virtually identical to the cumulative (placebo + active treatment) event rate in the first phase III efficacy trial (also 3.1 percent). As expected from previous clinical data, approximately 82 percent of isolates to date have represented serotype five or serotype eight infections. Nabi Biopharmaceuticals will next provide full results of the trial when the confirmatory phase III trial is completed in 2005.

In addition to reviewing infection event rates, the company also reported that the trial has been over-enrolled, which will result in further improvement in the statistical powering of the trial. A total of 3,976 patients were enrolled versus a target enrollment of 3,600 patients. The company made a decision to stop dosing in the study after a total of 3,447 patients had been randomized for injection with either StaphVAX or placebo. This was significantly greater than the trial design target of 3,240 patients. Patients in the trial were enrolled at over 400 clinical trial sites, and nearly 500 board-certified nephrologists (corresponding to approximately 10 percent of board-certified nephrologists in the United States) have participated in this study.

Dr. Rasmussen continued, "We are also encouraged by the level of excitement we encountered in the nephrology community about StaphVAX, as exemplified by the over-enrollment into this study and the number of physicians who expressed interest in enrolling their patients. The final sample size gives this study approximately 98 percent power to pick up an efficacy rate of 60 percent or greater and approximately 90 percent power to pick up an efficacy rate of 50 percent. We believe this high interest in enrolling patients is a clear validation of the magnitude of the medical challenge StaphVAX is being developed to address."

Source: Nabi Biopharmaceuticals