Intrapleural application of natural IFN alpha in breast cancer patients with pleural carcinomatosis. Monitoring of immunotherapy by assaying serum interferon levels.

For resistant local recurrence, e.g. in breast cancer, or metastatic spread, local infiltration of IFN may be an interesting new approach. The aim of this study was to find out if intrapleurally administered interferon, in breast cancer patients with pleural carcinomatosis, can cause measurable serum concentrations and how soon after administration. Serum IFN concentrations were compared with those in the pleural fluid, and correlated with the presence of malignant cells in the pleural fluid. To uncover possible rhythmicity of serum interferon levels and its relationship to the timing of therapy, natural leukocyte interferon was administered intrapleurally at 10 a.m. Data on pharmacokinetics were obtained from blood samples drawn at -2, 0, 2, 8, 14, 22 and 46 h during the course of treatment. In contrast to our previous observations in healthy volunteers, levels of serum IFN before therapy had no circadian rhythmicity. Daily pharmacokinetic profile of individual patients on interferon therapy has shown that serum IFN peaks 8 h after intrapleurally administered IFN alpha. The peak depended on frequency and number of applied doses. During treatment with IFN alpha, malignant cells degenerated and finally disappeared from pleural fluid. At the same time reactive cells appeared. This effect is rather uniformly observed, but varies in degree. The number of patients is too small, however, to permit conclusions in regard to correlation of this clinical effect and the levels of serum IFN alpha.