Vaccine may protect against post-arthroplasty Staph infections

Total hip and knee replacement patients treated with the vaccine experienced only mild adverse events similar to those seen with other vaccines.

A vaccine against Staphylococcus aureus may have potential for preventing postoperative infections in hip and knee replacement patients, according to Nabi Biopharmaceuticals, developers of the vaccine.

An immunogenicity study conducted in the United States to evaluate the safety of StaphVax (Staphylococcus aureus Polysaccharide Conjugate Vaccine) found that 94% of patients achieved antibody levels higher than estimated protective levels.

This compares favorably to a previous study involving immunocompromised end-stage renal disease (ESRD) patients, which found that 80% of patients achieved similar protective levels. Additionally, the antibody levels seen in the current study of orthopedic patients are consistent with the levels achieved in a study of cardiovascular surgery patients, according to a press release.

Nabi is developing StaphVax for preventing S. aureus infections in at-risk patients, including dialysis patients, patients undergoing cardiovascular, orthopedic and other surgeries, immunocompromised patients such as diabetics and cancer patients, and patients with previous S. aureus infections. The vaccine is currently in a U.S. confirmatory phase 3 trial for preventing S. aureus bloodstream infections in ESRD patients.

Increased antibody levels

The orthopedic study involved 120 total hip or knee replacement patients. Researchers vaccinated patients prior to surgery and evaluated the safety and immune response in a double-blinded manner over six weeks.

They found that vaccinated patients developed substantial increases in antibody levels after one week. At two weeks, 94% of patients had antibody levels higher than the estimated protective levels measured in immunocompromised ESRD patients, according to the press release.

Patients tolerated the vaccine well, with no serious vaccine-related adverse events. Vaccine-related adverse events were generally mild and of short duration, similar to events seen with other vaccines, company officials said in the release.

Nabi is also conducting an unblinded phase of this orthopedic study to generate a more comprehensive understanding of the vaccine’s duration of effect over 12 months.

The company continues to compile data from the phase 3 ESRD trial and expects to release additional data by November. It is also on schedule for filing a U.S. Biologics License Application for StaphVax in the fourth quarter of this year, which would include the results of the orthopedic surgery trial, company officials noted.

For more information:
Nabi Biopharmaceuticals; Web site: www.nabi.com