Toxicity following protein A treatment of metastatic breast adenocarcinoma

The toxic effects of protein A (Prosorba, IMRE Corporation, Seattle, WA) treatments given as part of an on-line plasmapheresis or off-line procedure were determined in a Phase I Study. Patients were randomized and treated 12 times either once per week or three times per week with a Prosorba column containing 50 or 200 mg protein A. Treated plasma volumes varied from 150 ml off-line to 2000 ml on-line. Seven patients having advanced metastatic breast adenocarcinoma patients were evaluated. All had advanced progressive disease that was resistant to chemotherapy and/or radiation therapy. Greater than 50% regression of measurable tumor volume occurred in four of seven patients; an additional patient responded with 33.5% regression. Two patients with only bony metastases demonstrated stable disease for a 60-day period. Side effects resulting from protein A treatments included transient fever, chills, rigors, and infrequently nausea, vomiting, diarrhea, episodic hyper and/or hypotension, bronchospasm, venospasm, headache, joint and tumor pain. Mild to moderate reactions were seen in all patients regardless of clinical response, but abated spontaneously or were controlled with pretreatment and/or post treatment with antipyretics and/or antihistaminics. The side effects decreased notably during the course of the week with the more intense reaction occurring during the first treatment of the week. Side effects occurred regardless of column size or volume of plasma treated. In the course of 12 treatments, anemia requiring transfusion developed in two of seven patients. Significant tumor regression was obtained in this group of patients with advanced disease. In light of the mild to moderate side effects and tumor regression in five of seven of the patients treated, protein A treatment merits further evaluation to determine the effectiveness of this treatment in breast adenocarcinoma.