In our previous study, MHO7 (6-epi-ophiobolin G, the structure is shown in Figure 1), which was produced by a mangrove fungus Aspergillus ustus 094102 [10], demonstrated potent antitumor activity against breast cancer cells (MCF-7) by the mechanism of down regulating estrogen receptor alpha (ERα) acting as a novel estrogen receptor degrader different from the known ERα inhibitors [11]. This evidence concerns the gene ESR1 and breast cancer.