As of 2007, it was estimated that approximately 94,000 invasive methicillin-resistant S. aureus (MRSA) infections occurred in the U.S. during the year 2005, and that these infections were associated with death in approximately 19,000 cases. Further, the economic burden of MRSA infections is substantial. MRSA hospitalizations cost nearly double that of non-MRSA hospitalizations; $14,000 for MRSA compared with $7,600 for non-MRSA. The average length of hospital stay for a patient with a MRSA infection is more than double that for non-MRSA stays - 10.0 days versus 4.6 days. These data support the need for the development of new therapies with novel mechanisms of action designed to either prevent or mitigate the progression of serious S. aureus infections.

Aurexis^® is a humanized monoclonal antibody with a high affinity and specificity to clumping factor A (ClfA), which is expressed by virtually all strains of S. aureus. ClfA is a cell surface fibrinogen binding protein that plays an important role in the initial adherence of bacteria to host tissues and implanted bio-materials, which is the first step in establishing a bacterial infection.

We believe there are a number of medical benefits that may be realized by using Aurexis^® as adjunctive therapy with antibiotics: first, reduced mortality and morbidity (complications) associated with S. aureus bacteremia; second, reduced length of stay in the intensive care unit, or ICU, thereby reducing the costs associated with a patient's overall hospital stay; third, reduced antibiotics utilization consistent with CDC and NIH guidelines, thereby reducing the likelihood of the development of antibiotic resistance; and fourth, reduced rates of relapse of infection. Moreover, the potential to be used prophylactically in high-risk patients may provide Aurexis^® with a unique advantage over antibiotics, as their prophylactic use is generally discouraged due to the potential for increased drug resistance.

We have completed several clinical trials of Aurexis^®, including a Phase 2a study in 60 patients with complicated S. aureus bacteremia. In the subjects and patients treated to date, Aurexis^® has generally been safe and well-tolerated, and data from the Phase 2a trial suggests Aurexis^® may have the potential to reduce the complications, morbidity and mortality associated with S. aureus bacteremia.