Cancer treatment with Staphylococcus aureus protein A.

For 3 years, Protein A of Staphylococcus aureus has been used in cancer treatment, initially because of its potential for removing serum blocking factors in the case of patients with malignancies. Extracorporeal adsorption of plasma over immobilized Protein A has produced beneficial effects on experimental animal cancers and some human tumors. The authors review various aspects of this apparently new form of immunotherapy: the basis of Protein A treatments according to the known effects of Protein A on the immune system; different techniques of plasma adsorption and especially the various Protein A carriers that have been used; the toxic effects which complicated the treatment course in several studies and their mechanisms; treatment results in animal models; and the results of phase I and II trials in patients.