Extracorporeal removal or modulation of circulating immune complexes (CIC) from plasma of animals and humans with malignant disease may be associated with induction of immune-mediated anti-tumor responses. Immunoadsorption columns containing heat-killed and formalin-fixed Staphylococcus aureus or staphylococcal protein A have been used for this purpose but treatments have often been associated with cardiopulmonary toxicity. Recently, an immunoadsorption device containing highly purified protein A covalently attached to a silica matrix (PROSORBA column) was used to treat 142 patients with refractory malignancies and 22 of 104 patients evaluated for anti-tumor response had objectively measurable reduction in tumor burden. In contrast to earlier experience with other devices, the procedures used in this trial were well tolerated and could be performed on an outpatient basis. The most common side effects observed among 1,306 treatments were chills (28% of treatments), low grade fever (28%), and musculoskeletal pain (16%). Side effects were mild to moderate and required no treatment or only symptomatic treatment. Treatment schedules were interrupted due to side effects for only six patients and there were no treatment-related deaths. Of 64 patients available for long-term follow-up evaluation (mean of 11 months), none exhibited evidence of long-term treatment-related side effects. None of the patient deaths in that period were associated with short or long-term treatment-related side effects. Protein A-silica (PROSORBA columns) can be used safely for development of further experimental treatments of malignant disease.

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