Download MendeleyApo-Form Selective Inhibition of IDO for Tumor Immunotherapy.
Liu, W., Zou, Y., Li, K., Zhong, H., Yu, L., Ge, S., Lai, Y., Dong, X., Xu, Q., Guo, W.(2022) J Immunol 209: 180-191
- PubMed: 35725271
- DOI: https://doi.org/10.4049/jimmunol.2100938
- Primary Citation of Related Structures:
8I7L - PubMed Abstract:
The pharmacological inhibition of IDO1 is considered an effective therapeutic approach for cancer treatment. However, the inadequate response of existing holo-IDO1 inhibitors and unclear biomarkers available in clinical practice limit the possibility of developing efficacious IDO1 inhibitors. In the current study, we aimed to elucidate the activity and mechanism of a potent 1 H -pyrrole-2-carboxylic acid derivative (B37) targeting apo-IDO1 and to determine its role in tumor therapy. By competing with heme for binding to apo-IDO1, B37 potently inhibited IDO1 activity, with an IC 50 of 22 pM assessed using a HeLa cell-based assay. The x-ray cocrystal structure of the inhibitor-enzyme complex showed that the B37-human IDO1 complex has strong hydrophobic interactions, which enhances its binding affinity, determined using isothermal titration calorimetry. Stronger noncovalent interactions, including π stacking and hydrogen bonds formed between B37 and apo-human IDO1, underlay the enthalpy-driven force for B37 for binding to the enzyme. These binding properties endowed B37 with potent antitumor efficacy, which was confirmed in a mouse colon cancer CT26 syngeneic model in BALB/c mice and in an azoxymethane/dextran sulfate sodium-induced colon carcinogenesis model in C57BL/6 mice by activating the host immune system. Moreover, the combination of B37 and anti-PD1 Ab synergistically inhibited tumor growth. These results suggested that B37 may serve as a unique candidate for apo-IDO1 inhibition-mediated tumor immunotherapy.
Organizational Affiliation:
State Key Laboratory of Pharmaceutical Biotechnology, Engineering Research Center of Protein and Peptide Medicine, School of Life Sciences, Nanjing University, Nanjing, People's Republic of China; and.
