Abstract: An EP300/CBP inhibitor, specifically provided is a compound as shown in formula I, or a deuterated product thereof, or a salt thereof, or a conformational isomer thereof, or a crystal form thereof, or a solvate thereof. The compound is highly selective for EP300/CBP, and can effectively inhibit the activity of EP300/CBP; in addition, the compound has an excellent inhibitory effect on various tumor cells including prostate cancer cells, leukemia cells, breast cancer cells and multiple myeloma cells. The compound has broad application prospects in the preparation of an EP300/CBP inhibitor, and drugs for preventing and/or treating tumors, myeloid hematopoietic stem/progenitor cells malignant disease, and regulating regulatory T cells.

Abstract: A compound represented by formula (I), or a stereochemical isomer thereof, or a solvate thereof, or a pharmaceutically acceptable salt thereof, can inhibit the activity of histone acetylase p300 and inhibit the proliferation activity of a variety of tumor cells.

Abstract: The compound of formula (I) has a good inhibitory effect on the proliferation of human prostate cancer cells CWR22RV1 and breast cancer cells; and combined use of the compound with an androgen receptor inhibitor HC-1119 significantly enhances the inhibitory effect on prostate cancer cells, and the inhibitory effect increases with increased concentration. The compound of formula (I) can not only be used independently to prepare an antineoplastic agent but can also be used in combination with other agents having antineoplastic effects, such as an androgen receptor inhibitor, or other targeting drugs etc., to prepare an antineoplastic agent having stronger therapeutic effects, especially an agent for treating prostate cancer and breast cancer.