Pharmakokinetics of Mistletoe Lectins after Intravenous Application of a Mistletoe Product in Healthy Subjects.

Mistletoe lectins (ML) have cytotoxic and immunomodulating properties, and subcutaneously applied mistletoe products (MP) containing ML have approval for supportive cancer treatment. MP are also given off-label intravenously, but data about pharmacokinetics are widely lacking. Therefore, the aim of our phase I trial was to evaluate the pharmacokinetics and safety of intravenously applied natural ML. Initially, 12 healthy male volunteers were planned to receive a single infusion of 2000 mg Helixor® P. We had to terminate the study prematurely after the inclusion of eight subjects due to elevation of all subjects' liver enzymes. ML was detected in all subjects after infusion. The mean half-life of serum ML was 7.02 ± 2.01 h. Mean alanine transaminase increased from 23 ± 6 to a maximum of 445 ± 260 U/L, and mean aspartate aminotransferase increased from 24 ± 3 to a maximum of 318 ± 33 U/L 72 h after infusion. Severity grading for drug-induced liver injury was mild. Participants did not suffer from any liver-specific symptoms and recovered completely. As a conclusion, the dose of 2000 mg Helixor® P caused transient liver injury in healthy subjects and should, therefore, not be used for initial patient treatment. Liver enzymes should be monitored in patients receiving intravenous treatment with Helixor® P.

Effects of mistletoe products on pharmacokinetic drug turnover by inhibition and induction of cytochrome P450 activities.

BACKGROUND: European mistletoe (Viscum album) products used in cancer therapy are frequently combined with other anti-cancer-drugs. Hence, potential herb-drug interactions have become a major safety concern in mistletoe therapy. METHODS: Three European mistletoe products (Helixor® A, Helixor® M and Helixor® P from mistletoe grown on firs, apple trees and pines, respectively) were tested for inhibition of nine major cytochrome P450 (CYP) isoenzymes in a test system using pooled human liver microsomes and for induction of five CYP isoforms in human hepatocytes cultivated in vitro according to the relevant guideline. RESULTS: Major inhibition did not occur in any of the CYP marker reactions. For some CYP isoenzymes, a minor or intermediate inhibition could be observed, but without dose effect relationship. Induction activity (≥ 1.5-fold increase) was not found with any of the three mistletoe products. CONCLUSION: Since no induction capacity was found and major inhibition above 50% did not occur even with the highest concentration used, which is approximately 100,000-fold higher than the clinically relevant dose in plasma, a clinically relevant herb-drug interaction is not expected for Helixor® A, M, and P.

Differential cytotoxic properties of Helleborus niger L. on tumour and immunocompetent cells.

ETHNOPHARMACOLOGICAL RELEVANCE: In Romanian folk medicine, Helleborus niger L. is used for the treatment of rheumatoid arthritis or viral infections and in complementary therapy, especially in anthroposophic medicine (AM), where the plant is administered as an adjuvant to treat malignant diseases. In the present study, we investigated the differential cytotoxic effects of H. niger on human tumour and healthy cells of the human immune system in vitro. MATERIAL AND METHODS: Protoanemonin and saponins, as significant constituents of H. niger extracts, were quantified in five individual batches using validated HPLC methods. Further, the impact of H. niger on proliferation capacity (MTT assay) as well as on apoptosis and necrosis induction in a panel of tumour cell lines and human lymphocytes (combined annexin V and propidium iodide staining) was monitored. In addition, NK cell function (degranulation-CD107a assay and IFN-gamma secretion) was also investigated since these immunocompetent cells are important for the control of malignancies within the human body. RESULTS: Extracts of H. niger induced proliferation inhibition not only of lymphoblastic leukaemia cells (MOLT4; IC50: 171 µg/mL) but also of myosarcoma (SK-UT-1b; IC50: 304 µg/mL) and melanoma cells (HT-144; IC50: 569 µg/mL) due to the induction of apoptosis. Purified T cells or NK cells were significantly affected through the presence of high H. niger concentrations while bulk lymphocytes were not affected. NK cells' anti-tumour functions expressed by degranulation capacity as well as IFN-y production were unaffected by the presence of the H. niger extract. Since protoanemonin and saponins have been reported in the literature to exert cytotoxic effects, their content was also determined. CONCLUSIONS: H. niger extracts exhibit differential cytotoxicity towards tumour cell lines and healthy human T- and NK-cells.

Viscum album L. extracts in breast and gynaecological cancers: a systematic review of clinical and preclinical research.

BACKGROUND: Viscum album L. extracts (VAE, European mistletoe) are a widely used medicinal plant extract in gynaecological and breast-cancer treatment. METHODS: Systematic review to evaluate clinical studies and preclinical research on the therapeutic effectiveness and biological effects of VAE on gynaecological and breast cancer. Search of databases, reference lists and expert consultations. Criteria-based assessment of methodological study quality. RESULTS: 19 randomized (RCT), 16 non-randomized (non-RCT) controlled studies, and 11 single-arm cohort studies were identified that investigated VAE treatment of breast or gynaecological cancer. They included 2420, 6399 and 1130 patients respectively. 8 RCTs and 8 non-RCTs were embedded in the same large epidemiological cohort study. 9 RCTs and 13 non-RCTs assessed survival; 12 reported a statistically significant benefit, the others either a trend or no difference. 3 RCTs and 6 non-RCTs assessed tumour behaviour (remission or time to relapse); 3 reported statistically significant benefit, the others either a trend, no difference or mixed results. Quality of life (QoL) and tolerability of chemotherapy, radiotherapy or surgery was assessed in 15 RCTs and 9 non-RCTs. 21 reported a statistically significant positive result, the others either a trend, no difference, or mixed results. Methodological quality of the studies differed substantially; some had major limitations, especially RCTs on survival and tumour behaviour had very small sample sizes. Some recent studies, however, especially on QoL were reasonably well conducted. Single-arm cohort studies investigated tumour behaviour, QoL, pharmacokinetics and safety of VAE. Tumour remission was observed after high dosage and local application. VAE application was well tolerated. 34 animal experiments investigated VAE and isolated or recombinant compounds in various breast and gynaecological cancer models in mice and rats. VAE showed increase of survival and tumour remission especially in mice, while application in rats as well as application of VAE compounds had mixed results. In vitro VAE and its compounds have strong cytotoxic effects on cancer cells. CONCLUSION: VAE shows some positive effects in breast and gynaecological cancer. More research into clinical efficacy is warranted.

Mistletoe extract reduces the surgical suppression of natural killer cell activity in cancer patients. a randomized phase III trial.

BACKGROUND: Major surgery suppresses natural killer (NK) cell cytotoxic activity which is potentially harmful for cancer patients by favouring haematogenic tumour cell dissemination. The influence of a perioperative infusion of a standardized mistletoe extract (Iscador) on immune functions was tested in a prospective, sequential, randomized clinical trial. PATIENTS AND METHODS: Colorectal cancer patients undergoing open tumour resection were randomly assigned to either mistletoe infusion or no additional therapy. We hypothesized that mistletoe infusion improves NK cell activity and increases expression of MHC class II antigen HLA-DR on monocytes 24 h and 7 days after surgery, respectively. For statistical analysis we used a sequential study design. The decision boundaries for the two triangular tests were calculated for altogether 62 patients. RESULTS: The sequential study design allowed stopping the recruitment prematurely. NK cell activity differed significantly between the therapy groups 24 h after surgery (p = 0.027). The absolute number of HLA-DR molecules on monocytes did not differ 7 days after surgery. NK cell activity of patients treated with mistletoe extract did not change significantly during the course of the study (-7.9% 24 h after surgery), whereas HLA-DR expression changed significantly (-38.5% at day 7 after surgery). For control patients both parameters decreased significantly after surgery (NK cell activity: -44.4% at 24 h; HLA-DR expression: -32.9% at day 7 after surgery). CONCLUSION: Perioperative infusion of mistletoe extracts can prevent a suppression of NK cell activity in cancer patients. The impact of this therapy on relapse and survival should be tested in further studies.

[Correlation of NK cell activity against autologous tumour cells and K562 cells with the clinical outcome during therapy with mistletoe extracts]. / Zusammenhang der NK-Zellaktivität gegen autologe Tumor- und K562-Zellen mit dem klinischen Verlauf unter Misteltherapie.

BACKGROUND: Suppression of NK cell activity is considered to be an unfavourable prognostic factor for tumour progression. There is proof that mistletoe extracts may increase NK cell activity. However, the inverse relation between an increase of NK cell activity and clinical progress of cancer has not been investigated. AIM AND DESIGN: The relation of NK cell activity and progress of cancer in patients under therapy with mistletoe extracts was examined in a prospective, monocentric, cohort study. At the same time the in vitro killing of K562 cells and autologous tumour cells was compared. PATIENTS AND METHODS: 40 patients with operable cancer of the breast or colon were included. The patients did not receive any immunologically relevant therapies except for mistletoe extracts. The absolute NK cell count in peripheral blood as well as the in vitro NK cell activity were monitored for up to 2 years and compared with clinical outcome as well as quality of life. RESULTS: The absolute NK cell count in peripheral blood increased within the observation period. Patients without progression had a significantly higher mean activity of NK cells against K562 cells than patients with progression. In the latter group, only stage IV patients showed reduced NK cell activity. The killing activity against autologous tumour cells was <5% in about 77.5% of the patients and could not be evaluated further. The NK cell activity against K562 cells was not related to the number of NK cells. CONCLUSIONS: We found a relation between NK cell activity and the progression of malignant disease. In further studies the causality of this relation has to be clarified. The establishment of NK cell activity against autologous tumour cells as a suitable parameter during follow-up was not successful.