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Discovery of 5-imidazole-3-methylbenz[d]isoxazole derivatives as potent and selective CBP/p300 bromodomain inhibitors for the treatment of acute myeloid leukemia

Acta Pharmacologica Sinica volume 46, pages 1706–1721 (2025)Cite this article

Abstract

Inhibition of the bromodomain of the cAMP response element binding protein (CREB)-binding protein (CBP) and its homologue p300 is an attractive therapeutic approach in oncology, particularly in acute myeloid leukemia (AML). In this study we describe the design, optimization, and evaluation of 5-imidazole-3-methylbenz[d]isoxazoles as novel, potent and selective CBP/p300 bromodomain inhibitors. Two of the representative compounds, 16t (Y16524) and 16u (Y16526), bound to the p300 bromodomain with IC50 values of 0.01 and 0.03 μM, respectively. Furthermore, 16t and 16u potently inhibited the growth of AML cell lines, particularly MV4;11 cells with IC50 values of 0.49 and 0.26 μM, respectively. The potent CBP/p300 bromodomain inhibitors represent a new class of compounds for the development of potential therapeutics against AML.

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Fig. 1: Structures of representative CBP/p300 bromodomain inhibitors.
Fig. 2: Flowchart summarizing the discovery and optimization strategy for novel 5-imidazole-3-methylbenz[d]isoxazole-containing CBP/p300 bromodomain inhibitors.
Scheme 1
Scheme 2
Fig. 3: Cocrystal structure of 16t bound to p300 bromodomain.
Fig. 4: Thermal stability shift analysis for selected compounds against bromodomains of CBP/p300 and BET proteins.
Fig. 5: Growth inhibitory effects of CBP/p300 inhibitors in different AML cell lines.
Fig. 6: Compounds 16t and 16 u inhibit the expression of c-Myc and PARP proteins.

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Acknowledgements

This work was supported in part by grants from the National Key R&D Program of China (grant 2022YFE0210600), the Guangdong Province Grant for Belt and Road Joint Laboratory (grant 2022B1212050004), the Basic Research Project of Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences (grant GIBHBRP24-04 and GIBHBRP24-03), research initiation project of Guoke Ningbo Life Science and Health Industry Research Institute (grant 2021YJY1007 and 2022YJY0206), the Zhu Xiu Shan Talent Project of Ningbo No. 2 Hospital (grant 2023HMYQ21), Youth Innovation Promotion Association CAS (grant No. 2023372), the National Natural Science Foundation of China (grants 22007088). We thank the staff at BL19U1/BL02U1 beamlines at SSRF of the National Facility for Protein Science in Shanghai (NFPS), Shanghai Advanced Research Institute, Chinese Academy of Sciences, for providing technical support in X-ray diffraction data collection and analysis. We gratefully acknowledge the support from the Guangzhou Branch of the Supercomputing Center, the Analysis and Testing Center and the Laboratory Animal Research Center of Chinese Academy of Sciences. We also thank the Scientific Data Center of Guangzhou Institutes of Biomedicine and Health, CAS (No. 011).

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Author notes

  1. These authors contributed equally: Jian-kang Hu, Xin Tang, Guo-long Luo.

Authors and Affiliations

  1. China-New Zealand Joint Laboratory of Biomedicine and Health, State Key Laboratory of Respiratory Disease, Guangdong Provincial Key Laboratory of Biocomputing, Institute of Drug Discovery, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou, 510530, China

    Jian-kang Hu, Guo-long Luo, Cheng Zhang, Tian-bang Wu, Chao Wang, Hui Shen, Xi-shan Wu, Yong Xu & Yan Zhang

  2. Joint School of Life Sciences, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences and Guangzhou Medical University, Guangzhou, 510530, China

    Xin Tang & Xiao-fan Zhao

  3. University of Chinese Academy of Sciences, Beijing, 100049, China

    Guo-long Luo

  4. Auckland Cancer Society Research Centre, School of Medical Sciences, The University of Auckland, Auckland, New Zealand

    Jeff B. Smaill

  5. Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, New Zealand

    Jeff B. Smaill

  6. Guoke Ningbo Life Science and Health Industry Research Institute, Ningbo No. 2 Hospital, Ningbo, 315010, China

    Qiu-ping Xiang

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Contributions

YX, QPX, and YZ conceived and designed the research. JKH, XT, GLL, CZ, TBW, CW, HS, XFZ, XSW, and YZ conduct the research. QPX, YX, YZ, and JKH wrote the manuscript. QPX, YX, YZ, JBS, and JKH revised the manuscript. All authors reviewed the results and approved the final version of the manuscript.

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Correspondence to Yong Xu, Yan Zhang or Qiu-ping Xiang.

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Hu, Jk., Tang, X., Luo, Gl. et al. Discovery of 5-imidazole-3-methylbenz[d]isoxazole derivatives as potent and selective CBP/p300 bromodomain inhibitors for the treatment of acute myeloid leukemia. Acta Pharmacol Sin 46, 1706–1721 (2025). https://doi.org/10.1038/s41401-025-01478-x

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