American Association for Cancer Research
00085472can153099-sup-158057_1_supp_3349727_424vfv.doc (2.23 MB)

Supplementary Figure S1 from Novel Protein Disulfide Isomerase Inhibitor with Anticancer Activity in Multiple Myeloma

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journal contribution
posted on 2023-03-31, 00:03 authored by Sergei Vatolin, James G. Phillips, Babal K. Jha, Shravya Govindgari, Jennifer Hu, Dale Grabowski, Yvonne Parker, Daniel J. Lindner, Fei Zhong, Clark W. Distelhorst, Mitchell R. Smith, Claudiu Cotta, Yan Xu, Sujatha Chilakala, Rebecca R. Kuang, Samantha Tall, Frederic J. Reu

Structure, H-NMR and HRMS of CCF642, B-CCF642 and CCF642-COOH


Robert Tomsich


Nancy Vacc

ACS pilot

Scott Hamilton Cares Initiative




Multiple myeloma cells secrete more disulfide bond–rich proteins than any other mammalian cell. Thus, inhibition of protein disulfide isomerases (PDI) required for protein folding in the endoplasmic reticulum (ER) should increase ER stress beyond repair in this incurable cancer. Here, we report the mechanistically unbiased discovery of a novel PDI-inhibiting compound with antimyeloma activity. We screened a 30,355 small-molecule library using a multilayered multiple myeloma cell–based cytotoxicity assay that modeled disease niche, normal liver, kidney, and bone marrow. CCF642, a bone marrow–sparing compound, exhibited a submicromolar IC50 in 10 of 10 multiple myeloma cell lines. An active biotinylated analog of CCF642 defined binding to the PDI isoenzymes A1, A3, and A4 in MM cells. In vitro, CCF642 inhibited PDI reductase activity about 100-fold more potently than the structurally distinct established inhibitors PACMA 31 and LOC14. Computational modeling suggested a novel covalent binding mode in active-site CGHCK motifs. Remarkably, without any further chemistry optimization, CCF642 displayed potent efficacy in an aggressive syngeneic mouse model of multiple myeloma and prolonged the lifespan of C57BL/KaLwRij mice engrafted with 5TGM1-luc myeloma, an effect comparable to the first-line multiple myeloma therapeutic bortezomib. Consistent with PDI inhibition, CCF642 caused acute ER stress in multiple myeloma cells accompanied by apoptosis-inducing calcium release. Overall, our results provide an illustration of the utility of simple in vivo simulations as part of a drug discovery effort, along with a sound preclinical rationale to develop a new small-molecule therapeutic to treat multiple myeloma. Cancer Res; 76(11); 3340–50. ©2016 AACR.