A Phase I trial of endoxifen, an active metabolite of the cancer drug tamoxifen, indicates that the experimental drug is safe, with early evidence for anti-tumor activity, a Mayo Clinic study has found. The findings indicate that Z-endoxifen, co-developed by Mayo Clinic Cancer Center and the National Cancer Institute, may provide a new and better treatment for some women with estrogen positive breast cancer and, in particular, for those women who do not respond to tamoxifen and aromatase inhibitors.
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