Clinical results and immunologic effects of a mixed bacterial vaccine in cancer patients.

A biological response modifier, mixed bacterial vaccine (MBV), derived from Streptococcus pyogenes and Serratia marcescens was used as a single agent in the treatment of 11 patients with refractory malignancies. MBV's effect on interleukin-2 (IL-2) production, plasma interferon (IFN) and tumor necrosis factor (TNF) levels was monitored. Most patients' peripheral blood mononuclear cells continued to produce baseline to elevated levels of IL-2, in spite of age and disease status. Several patients maintained moderate to high IFN levels. In general there was little correlation between IL-2 and IFN levels or with the response to therapy. One of 11 patients had minor response, 1 of 11 had partial response, 4 of 11 had temporary stabilization of disease, and 5 of 11 had progressive disease. A patient with AIDS and Kaposi's sarcoma experienced a dramatic improvement in performance status and disease stabilization. In all patients side effects occurred only following i.v. and not i.m. administration and included fever and chills. No adverse hepatic, renal or hematologic effects were observed. MBV is a well-tolerated biological response modifier with modest activity in advanced human tumors.