The challenges of developing an effective vaccine against S. aureus due to the different strains and evasion mechanisms have been well documented. Clinical results with vaccines and therapeutic IgG antibodies suggest failure is a result of S. aureus’ evasion of humoral immunity.
XBiotech has completed enrollment in a Phase I/II randomized, placebo-controlled, dose escalation study for the treatment of serious infections due to S. aureus. Patients with these types of infections typically have severe complications, extended hospital stays, and a 30-day mortality of approximately 20 percent. The 514G3 monoclonal targets all forms of S. aureus, mediates phagocytosis, and neutralizes the immune evasion mechanism. The first patient, enrolled in July 2015, showed signs of recovery within 24 hours of a single low dose of therapy and data to date shows direct correlation with the PK of antibody therapy and ability of treated patients’ blood to mediate clearance of S. aureus in vitro.
The U.S. FDA, recognizing the potential of this treatment, has designated this as a Fast Track development program.