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StaphVAX(R) Immunogenicity Study in Cardiac Patients Meets Primary Endpoints of Safety and Immune Response

Posted on: Tuesday, 12 July 2005, 09:00 CDT

BOCA RATON, Fla., July 12 /PRNewswire-FirstCall/ -- Nabi Biopharmaceuticals announced today positive results from the first in a series of immunogenicity studies of StaphVAX(R) (Staphylococcus aureus Polysaccharide Conjugate Vaccine) in additional patient populations at risk for S. aureus infections. StaphVAX is Nabi Biopharmaceuticals' phase 3 investigational vaccine designed to prevent the most prevalent strains of S. aureus bacterial infections.

Patients undergoing various types of surgery, including cardiovascular surgery, are at increased risk of developing severe S. aureus infections. The risk is greatest during the immediate post-operative period while patients are still in the hospital and the next few weeks while recovering from surgery. This study was designed to provide evidence that a broader and generally healthier at-risk patient group, such as patients undergoing cardiovascular surgery, can achieve antibody levels equal to, or greater than, the protective antibody levels attained in immunocompromised end-stage renal disease (ESRD) patients in earlier clinical trials. In addition, the study was designed to assess safety and toleration of the vaccine in these patients.

The phase 2b immunogenicity study included a total of 120 patients from 15 cardiovascular surgery centers in the United States. This two-part, six-month study was double-blinded through the first six weeks following vaccination, when surgery patients are at greatest risk for post-surgical infections. Subjects were vaccinated prior to their cardiovascular procedure in order to assess their antibody levels during the period of greatest risk of S. aureus infection. While these patients were healthier than the ESRD patients studied in the Company's phase 3 efficacy trial, 25 percent were partially immunocompromised due to diabetes. Substantial increases in antibody levels were achieved in the vaccine recipients by day 7, and by day 14, the levels were far above the estimated protective antibody levels measured in compromised ESRD patients. On day 14, 93 percent of the patients had antibody levels above the estimated protective levels. This compares favorably to the 80-85 percent response rate observed in ESRD patients. The vaccine was very well tolerated. No serious adverse events were attributed to the vaccine. Reactions to the vaccine were generally mild and of short duration, similar to those experienced by ESRD patients. The second, unblinded phase of the study, which will provide more comprehensive assessment of the duration of vaccine effect in this population by following patients for up to six months, is still ongoing.

"These results support the potential to broaden the patient population beyond dialysis patients who can benefit from the protection afforded by StaphVAX against S. aureus. We expect to include these results in our 2005 Biologics License Application filing in the United States as well as a supplemental Marketing Authorization Application in Europe," stated Henrik S. Rasmussen, M.D., Ph.D., senior vice president, clinical, medical and regulatory affairs, Nabi Biopharmaceuticals. "This study is firmly aligned with our commercial growth strategy to build the industry's broadest and deepest Gram-positive bacterial infections franchise. We look forward to presenting the full dataset from this study at an upcoming scientific meeting, and as a full paper."

StaphVAX is currently in a confirmatory phase 3 trial designed to confirm that it can prevent S. aureus infections in ESRD patients. Patients with ESRD are at high risk of developing S. aureus bacterial infections and are among the most difficult patients to treat because they are immunocompromised due to their debilitating, underlying disease and because dialysis access provides an opportunity for bacteria to be introduced into their bloodstream. However, there are a large number of other patient populations who are at substantial risk for contracting S. aureus infections, such as patients undergoing cardiothoracic or orthopedic surgery, in particular when it involves implantation of prosthetic devices. It is estimated that there are a total of 12 million patients in the United States who are at risk of contracting these infections on an annual basis.

About S. aureus Infections

S. aureus is the most common cause of serious hospital-acquired bloodstream infections. Staphylococcal infections are difficult to treat because the bacteria, in most cases, is resistant to available antibiotics. This rise of antibiotic resistance has markedly curtailed options for treating S. aureus infections. According to the current estimates by the U.S. Centers for Disease Control and Prevention (CDC), more than two million patients in the United States each year contract an infection as a result of exposure to a pathogen while receiving care in a hospital. 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, liver 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 chronic illnesses such as diabetes, cancer, or lung or kidney diseases. People whose immune systems are suppressed due to disease, chemotherapy, or radiation therapy are generally more susceptible to these bacterial infections.

About S. aureus Infections and Resistance Issues

An estimated 12 million patients are at risk for developing an S. aureus infection each year in the United States. In the country's 7,000 acute care hospitals, S. aureus is the leading cause of hospital-based bloodstream infections and has a crude mortality rate of 25 percent. The risk is highest for patients who are immunocompromised and for those who suffer from chronic debilitating illnesses, as well as for people treated with invasive devices such as a prosthetic or dialysis devices. S. aureus bacteria are becoming increasingly resistant to available antibiotics. It is estimated that over 95 percent of patients worldwide with S. aureus infections no longer respond to first-line antibiotics, such as penicillin or ampicillin. Methicillin is an alternative treatment, but nearly 60 percent of strains of S. aureus in the United States are now methicillin-resistant, and this number continues to rise. In other parts of the developed world, the rate of methicillin- resistant S. aureus incidence continues to grow, with resistance rates close to 80 percent in some Asian countries.

About Nabi Biopharmaceuticals' Hospital-Acquired Infections Franchise

The annual economic cost of hospital-acquired infections totals approximately $30 billion in the United States. Nabi Biopharmaceuticals is building a franchise of products to prevent and treat the approximately two million patients who contract these infections each year. The Company's strategy to advance this franchise is three-fold:

Prevent and Treat the Clinical Problem: Infections keep patients in the hospital longer and greatly increase illness, death and cost. Nabi Biopharmaceuticals is pursuing a combination approach, starting with Altastaph(TM) [Staphylococcus aureus Immune Globulin Intravenous (Human)] and StaphVAX, to offer patients prevention and treatment for hospital-acquired bacterial infections and, upon hospital discharge, prevention of longer-term relapse after an infection. This innovative approach, initially focused on S. aureus infections, will be expanded to include S. epidermidis, Enterococcus and Gram-negative infections.

Leverage the Technology: Nabi Biopharmaceuticals believes it has a core, patented technology that will overcome the resistance challenges associated with current antibiotics.

Build a Risk-balanced Platform: Nabi Biopharmaceuticals is developing a portfolio of products to address the most prevalent and dangerous hospital- acquired infections, including S. aureus, S. epidermidis, Enterococcus, Pseudomonas and other Gram-negative bacteria and fungi, for the broadest array of at-risk patients.

About Nabi Biopharmaceuticals

Nabi Biopharmaceuticals leverages its experience and knowledge in powering the immune system to develop and market products that fight serious medical conditions. We are poised to capture large, commercial opportunities in our four core business areas: Gram-positive bacterial infections, hepatitis, kidney disease (nephrology), and nicotine addiction. We have three products on the market today: PhosLo(R) (calcium acetate), Nabi-HB(R) [Hepatitis B Immune Globulin (Human)], and Aloprim(TM) [Allopurinol sodium (for injection)] and a number of products in various stages of clinical and preclinical development. The Company filed its Marketing Authorization Application in Europe for its product candidate, StaphVAX(R) [Staphylococcus aureus Polysaccharide Conjugate Vaccine], in December 2004. The application was accepted for review in January 2005. StaphVAX is currently in a confirmatory phase 3 clinical trial in the United States. StaphVAX is designed to prevent the most dangerous and prevalent strains of S. aureus bacterial infections. S. aureus bacteria are a major cause of hospital-acquired infections and are becoming increasingly resistant to antibiotics. The Company's other products in development include Altastaph(TM) [Staphylococcus aureus Immune Globulin Intravenous (Human)], an antibody for prevention and treatment of S. aureus infections, NicVAX(TM) [Nicotine Conjugate Vaccine], a vaccine to treat nicotine addiction, and Civacir(TM) [Hepatitis C Immune Globulin (Human)], an antibody for preventing hepatitis C virus re-infection in liver transplant patients. For additional information on Nabi Biopharmaceuticals, please visit our website at: http://www.nabi.com/ .

This press release contains forward-looking statements that reflect the Company's current expectations regarding future events. Any such forward- looking statements are not guarantees of future performance and involve significant risks and uncertainties. Actual results may differ significantly from those in the forward-looking statements as a result of any number of factors, including, but not limited to, risks relating to the possibility that our confirmatory phase 3 clinical trial for StaphVAX or our plans to commercialize StaphVAX in the European Union and in the United States may not be successful; the risk that StaphVAX is not effective in patients who undergo cardiovascular surgery, the ability to file the BLA in the United States and the MAA in Europe, the Company's ability to raise additional capital on acceptable terms; the Company's dependence upon third parties to manufacture its products; the Company's ability to utilize the full capacity of its manufacturing facility; reliance on a small number of customers; the future sales growth prospects for the Company's biopharmaceutical products; and the Company's ability to obtain regulatory approval for its products in the United States or abroad or to successfully develop, manufacture and market its products. These factors are more fully discussed in the Company's Annual Report on Form 10-K for the fiscal year ended December 25, 2004 filed with the Securities and Exchange Commission.

Nabi Biopharmaceuticals

CONTACT: Constance C. Bienfait, Vice President, Investor Relations ofNabi Biopharmaceuticals, +1-561-989-5800

Web site: http://www.nabi.com/

Source: PRNewswire-FirstCall

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