The efficacy of large volume plasma exchange in chemotherapy resistant malignancies.

Chemotherapy resistance in cancer patients may be due to serum blocking factors, which can be diminished or eliminated by large volume plasma exchange (PE). This procedure was performed with the IBM blood cell separator in 69 patients resistant to chemotherapy. Immediately after PE the chemotherapy was given but it was reinstituted, if clinical evaluation revealed partial remission, minor response or no change. 37 out of 69 patients (53.6%) responded again, 32 (46.4%) did not. Response duration ranged from 2 to 45 weeks. Best clinical results were obtained in patients with colorectal cancer, 15 out of 23 showed improvement between 4 to 45 weeks. Serum blocking activity was measured using a modified mixed lymphocyte culture assay (MLC). There was a 80% positive correlation between clinical course of patients and MLC levels, if basic activity before the first PE was compared to MLC inhibition before the following PE's.