Anticancer Activity of a Lectin-rich Mistletoe Extract Injected Intratumorally into Human Pancreatic Cancer Xenografts

Abstract

Background: In single case observations, tumour remissions after intratumoral injections of mistletoe extracts have been described. Materials and Methods: We investigated the antitumour activity of intratumorally (i.t.)-injected lectin-rich mistletoe extract at different dosages and i.t.-injected mistletoe lectin I in comparison to intravenous (i.v.) Gemcitabine and i.t. treatment with placebo in a human pancreatic cancer xenograft. Results: In a preliminary dose-response experiment, the most marked tumour inhibition was induced when mistletoe extract was given at 8 mg/kg body weight (BW) and mistletoe lectin I at 5.3 μg/kg BW. In a second experiment, bi-weekly i.t. injections of mistletoe extract over 8 weeks resulted in a very high antitumour activity with an optimal T/C value (=median relative tumour volume of the test group vs. the control) of 0.4% combined with 3/8 partial and 3/8 complete remissions. Gemcitabine was less active with 2/8 partial and 1/8 complete remissions and an optimal T/C of 4.6%. Conclusion: I.t.-injected lectin-rich mistletoe extract should be further evaluated in patients with inoperable locally advanced pancreatic cancer.