Clinical trials with staphylococcal protein A.
Several reports have indicated antitumor effects from the immunoadsorption of plasma from tumor-bearing animals and humans with protein A-containing Staphylococcus aureus. The columns used for these treatments have varied widely in design. In a Phase I trial at the University of Washington, we used protein A chemically linked to crystalline silica for continuous immunoadsorption of plasma in 20 patients with advanced malignancies. Separated blood was perfused continuously over columns containing 50-100 g of immunoadsorbent with 100-200 mg protein A. One calculated plasma volume was perfused over the columns for each treatment. Patients received between 1 and 22 treatments, in total, at one to three treatments per week. Two patients had in vitro treatment of plasma separated from a unit of whole blood obtained by phlebotomy. Side effects were common, were usually manageable, and included chills and fever, nausea, tumor pain, hypotension, and respiratory symptoms. The observed antitumor responses were modest. Three of seven patients with melanoma had indications of responses less than 50%. One of three patients with breast cancer had a response less than 50%. The above studies demonstrate the feasibility of using staphylococcal protein A immunoadsorption in a larger group of patients with a more favorable disease stage.