In an in vitro study, the estrogen receptor-positive human breast cancer cell line MCF-7 was treated with different concentrations of endoxifen, the main metabolite of tamoxifen, in the presence and absence of defined estradiol concentrations . Each concentration of this drug was combined with Iscador in clinically relevant doses and investigated for inhibition of proliferation, apoptosis and cell cycle.
It could be shown that mistletoe extracts do not induce inhibition of endoxifen-induced cytostasis and cytotoxicity. Mistletoe extracts also did not inhibit the CYP3A4/5 and CYP2D6 catalyzed tamoxifen metabolism. On the contrary: mistletoe extracts in higher concentrations in combination with tamoxifen even had an additive tumour-inhibitory effect on the proliferation of tumour cells.
Prospective clinical studies on the combination of mistletoe preparations with antihormonal drugs are expected in the coming years.
Last update: July 15th, 2020/AT