Cellular Immunomodulation and Safety of Standardized Aqueous Mistletoe Extract PS76A2 in Tumor Patients Treated for 48 Weeks

Abstract

Non-selected tumor patients (n=12) with various solid carcinomas were treated continuously twice weekly over 48 weeks with the aqueous mistletoe extract PS76A2, standardized to active mistletoe lectin. The preparation was applied subcutaneously at a concentration of 15 ng mistletoe lectin per 0.5 ml. Cellular immune response and safety were determined at various times during and after the therapy. In the course of treatment, virtually all the investigated immunoparameters were raised compared to the baseline values at the start of treatment. The statistically significant rises in the cell count of total lymphocytes, monocytes and natural killer (NK) cells was noteworthy. The differences in comparison with the baseline values at the various measuring times during treatment were up to 35%. In the first weeks of treatment at least, the raised cell count of NK cells correlated with the significantly increased cytotoxic activity versus tumor cells ex vivo. The NK factor (product of NK cells and ex vivo activity) was determined to assess the total NK activity more accurately, which rose up to 50% compared to the baseline value. Other lymphatic subpopulations, for instance CD3+, CD8+, CD3+CD4+ and CD3+CD8+ cells, also revealed distinct rises in cell count in the course of treatment. Within 6 weeks after completion of treatment, the overall values dropped again; but for a series of immunoparameters - in particular for the NK cells - they were still raised in comparison to the baseline values. The extensive laboratory diagnostics (haematology, clinical chemistry) showed that treatment with the standardized mistletoe extract PS76A2 was well tolerated by all patients. In single cases, local reactions at the injection sites were of a minor nature and reversible within two days. Summarizing, it can be stated that the standardized mistletoe extract PS76A2 significantly improved the immune status of tumor patients and was administered safely over a long period.