The anti-mitotic agents PTC-028 and PTC596 display potent activity in pre-clinical models of multiple myeloma but challenge the role of BMI-1 as an essential tumour gene.
[en] Future progress in the treatment of multiple myeloma (MM) requires both the characterisation of key drivers of the disease and novel, innovative approaches to tackle these vulnerabilities. The present study focussed on the pre-clinical evaluation of a novel drug class, BMI-1 modulators, in MM. We demonstrate potent activity of PTC-028 and PTC596 in a comprehensive set of in vitro and in vivo models, including models of drug resistance and stromal support. Treatment of MM cells with PTC-028 and PTC596 downregulated BMI-1 protein levels, which was found to correlate with drug activity. Surprisingly, BMI-1 was dispensable for the activity of BMI-1 modulators and MM cell growth. Our data rather point to mitotic arrest accompanied by myeloid cell leukaemia-1 (MCL-1) loss as key anti-MM mechanisms and reveal impaired MYC and AKT signalling activity due to BMI-1 modulator treatment. Moreover, we observed a complete eradication of MM after PTC596 treatment in the 5TGM.1 in vivo model and define epigenetic compounds and B cell leukaemia/lymphoma 2 homology domain 3 (BH3) mimetics as promising combination partners. These results bring into question the postulated role of BMI-1 as an essential MM gene and confirm BMI-1 modulators as potent anti-mitotic agents with encouraging pre-clinical activity that supports their rapid translation into clinical trials.
The anti-mitotic agents PTC-028 and PTC596 display potent activity in pre-clinical models of multiple myeloma but challenge the role of BMI-1 as an essential tumour gene.
Rajkumar SV. Multiple myeloma: 2016 update on diagnosis, risk-stratification and management. Am J Hematol. 2016;91:719–34.
Winter GE, Buckley DL, Paulk J, Roberts JM, Souza A, Dhe-Paganon S, et al. DRUG DEVELOPMENT. Phthalimide conjugation as a strategy for in vivo target protein degradation. Science (New York, N Y.), 348, 2015; p. 1376–81.
Jacobs JJ, Scheijen B, Voncken JW, Kieboom K, Berns A, van Lohuizen M. Bmi-1 collaborates with c-Myc in tumorigenesis by inhibiting c-Myc-induced apoptosis via INK4a/ARF. Genes & Development. 1999;13:2678–90.
Bhattacharya R, Banerjee Mustafi S, Street M, Dey A, Dwivedi SK. Bmi-1: At the crossroads of physiological and pathological biology. Genes Dis. 2015;2:225–39.
Bakhshinyan D, Venugopal C, Adile AA, Garg N, Manoranjan B, Hallett R, et al. BMI1 is a therapeutic target in recurrent medulloblastoma. Oncogene. 2019;38:1702–16.
Mariani SA, Minieri V, De Dominici M, Iacobucci I, Peterson LF, Calabretta B. CDKN2A-independent role of BMI1 in promoting growth and survival of Ph+ acute lymphoblastic leukemia. Leukemia. 2016;30:1682–90.
Sengupta A, Ficker AM, Dunn SK, Madhu M, Cancelas JA. Bmi1 reprograms CML B-lymphoid progenitors to become B-ALL-initiating cells. Blood. 2012;119:494–502.
Sparmann A, van Lohuizen M. Polycomb silencers control cell fate, development and cancer. Nat Rev Cancer. 2006;6:846–56.
Gil J, O'Loghlen A. PRC1 complex diversity: where is it taking us? Trends Cell Biol. 2014;24:632–41.
De Vos J, Thykjaer T, Tarte K, Ensslen M, Raynaud P, Requirand G, et al. Comparison of gene expression profiling between malignant and normal plasma cells with oligonucleotide arrays. Oncogene. 2002;21:6848–57.
Jagani Z, Wiederschain D, Loo A, He D, Mosher R, Fordjour P, et al. The Polycomb group protein Bmi-1 is essential for the growth of multiple myeloma cells. Cancer Res. 2010;70:5528–38.
Wu SQ, Xu ZZ, Niu WY, Huang HB, Zhan R. ShRNA-mediated Bmi-1 silencing sensitizes multiple myeloma cells to bortezomib. Int J Mol Med. 2014;34:616–23.
Alzrigat M, Párraga AA, Majumder MM, Ma A, Jin J, Österborg A, et al. The polycomb group protein BMI-1 inhibitor PTC-209 is a potent anti-myeloma agent alone or in combination with epigenetic inhibitors targeting EZH2 and the BET bromodomains. Oncotarget. 2017;8:103731–43.
Bolomsky A, Schlangen K, Schreiner W, Zojer N, Ludwig H. Targeting of BMI-1 with PTC-209 shows potent anti-myeloma activity and impairs the tumour microenvironment. J Hematol Oncol. 2016;9:17. DOI: 10.1186/s13045-016-0247-4.
Kim MJ, Cao L, Sheedy J, Risher N, Dumble M, Lee CS, et al. Abstract 5517: PTC596-induced Bmi1 hyper-phosphorylation via Cdk1/2 activation resulting in tumor stem cell depletion. Cancer Res. 2014;74:5517.
Eberle-Singh JA, Sagalovskiy I, Maurer HC, Sastra SA, Palermo CF, Decker AR, et al. Effective delivery of a microtubule polymerization inhibitor synergizes with standard regimens in models of pancreatic ductal adenocarcinoma. Clin Cancer Res. 2019;25:5548–60.
Bolomsky A, Heusschen R, Schlangen K, Stangelberger K, Muller J, Schreiner W, et al. Maternal embryonic leucine zipper kinase is a novel target for proliferation-associated high-risk myeloma. Haematologica. 2018;103:325–35.
Mihara K, Imai C, Coustan-Smith E, Dome JS, Dominici M, Vanin E, et al. Development and functional characterization of human bone marrow mesenchymal cells immortalized by enforced expression of telomerase. Br J Haematol. 2003;120:846–9.
Muller J, Bolomsky A, Dubois S, Duray E, Stangelberger K, Plougonven E, et al. Maternal embryonic leucine zipper kinase inhibitor OTSSP167 has preclinical activity in multiple myeloma bone disease. Haematologica. 2018;103:1359–68.
DepMap B. DepMap Achilles 19Q1 Public., 2019. Available at: https://figshare.com/articles/DepMap_Achilles_19Q1_Public/7655150 Accessed May 2, 2019.
Meyers RM, Bryan JG, McFarland JM, Weir BA, Sizemore AE, Xu H, et al. Computational correction of copy number effect improves specificity of CRISPR-Cas9 essentiality screens in cancer cells. Nature Genetics. 2017;49:1779–84.
Millman SE, Pagano M. MCL1 meets its end during mitotic arrest. EMBO Reports. 2011;12:384–5.
Gu C, Yang Y, Sompallae R, Xu H, Tompkins VS, Holman C, et al. FOXM1 is a therapeutic target for high-risk multiple myeloma. Leukemia. 2016;30:873–82.
Nishida Y, Maeda A, Kim MJ, Cao L, Kubota Y, Ishizawa J, et al. The novel BMI-1 inhibitor PTC596 downregulates MCL-1 and induces p53-independent mitochondrial apoptosis in acute myeloid leukemia progenitor cells. Blood Cancer J. 2017;7:e527.
Lub S, Maes A, Maes K, De Veirman K, De Bruyne E, Menu E, et al. Inhibiting the anaphase promoting complex/cyclosome induces a metaphase arrest and cell death in multiple myeloma cells. Oncotarget. 2016;7:4062–76.
Cho JH, Dimri M, Dimri GP. A Positive Feedback Loop Regulates the Expression of Polycomb Group Protein BMI1 via WNT Signaling Pathway. J Biol Chem. 2013;288:3406–18.
Clarke PR, Allan LA, Skowyra A. Timed degradation of Mcl-1 controls mitotic cell death. Mol Cell Oncol. 2018;5:e1516450.
Gascoigne KE, Taylor SS. Cancer cells display profound intra- and interline variation following prolonged exposure to antimitotic drugs. Cancer Cell. 2008;14:111–22.
Gomez-Bougie P, Maiga S, Tessoulin B, Bourcier J, Bonnet A, Rodriguez MS, et al. BH3-mimetic toolkit guides the respective use of BCL2 and MCL1 BH3-mimetics in myeloma treatment. Blood. 2018;132:2656–69.
Gong JN, Khong T, Segal D, Yao Y, Riffkin CD, Garnier JM, et al. Hierarchy for targeting prosurvival BCL2 family proteins in multiple myeloma: pivotal role of MCL1. Blood. 2016;128:1834–44.
Wuillème-Toumi S, Robillard N, Gomez P, Moreau P, Le Gouill S, Avet-Loiseau H, et al. Mcl-1 is overexpressed in multiple myeloma and associated with relapse and shorter survival. Leukemia. 2005;19:1248–52.
Bennett A, Sloss O, Topham C, Nelson L, Tighe A, Taylor SS. Inhibition of Bcl-xL sensitizes cells to mitotic blockers, but not mitotic drivers. Open Biol. 2016;6:160134.
Shi J, Zhou Y, Huang HC, Mitchison TJ. Navitoclax (ABT-263) accelerates apoptosis during drug-induced mitotic arrest by antagonizing Bcl-xL. Cancer Res. 2011;71:4518–26.
Sloss O, Topham C, Diez M, Taylor S. Mcl-1 dynamics influence mitotic slippage and death in mitosis. Oncotarget. 2016;7:5176–92.
Jin X, Kim LJY, Wu Q, Wallace LC, Prager BC, Sanvoranart T, et al. Targeting glioma stem cells through combined BMI1 and EZH2 inhibition. Nat Med. 2017;23:1352–61.
Kikuchi J, Koyama D, Wada T, Izumi T, Hofgaard PO, Bogen B, et al. Phosphorylation-mediated EZH2 inactivation promotes drug resistance in multiple myeloma. J Clin Investigat 2015;125:4375–90.
Grant S. HDAC inhibitors repress the polycomb protein BMI1. Cell Cycle. 2010;9:2722–30.
Gabrielli B, Chia K, Warrener R. Finally, how histone deacetylase inhibitors disrupt mitosis! Cell Cycle. 2011;10:2658–61.
Ramakrishnan VG, Miller KC, Macon EP, Kimlinger TK, Haug J, Kumar S, et al. Histone deacetylase inhibition in combination with MEK or BCL-2 inhibition in multiple myeloma. Haematologica. 2019;104:2061–74.