Abstract 1654: The small molecule YK-4-279 shows anti-lymphoma activity in pre-clinical models
Authors: Chung Elain YL , Priebe Valdemar , Gaudio Eugenio , Kwee Ivo , Tarantelli Chiara , Rinaldi Andrea , Carrassa Laura , Testoni Monica , Cascione Luciano , Broggini Massimo , Toretsky Jeffrey A. , Zucca Emanuele , Bertoni Francesco 
Published: August 2015

Abstract
We have reported that up to 20% of diffuse large B cell lymphomas (DLBCL) present recurrent 11q23 gains leading to deregulated expression of the two transcription factors ETS1 and FLI1 and silencing of FLI1 was shown to lead to cell death in 6/6 DLBCL cell lines (Blood 2013). YK-4-279 is a small molecule that inhibits the binding of EWS1-FLI1 to RHA, leading to growth arrest and apoptosis of pre-clinical models of Ewing Sarcoma (Nat Med 2009). RHA is transcriptional co-activator, part of the EWS1-FLI1 transcription complex, but also involved in the activity of NFKB and STAT transcription complexes. Indeed, the compound also presented anti-cancer activity in a few additional cancer cell lines perhaps targeting not EWS1-FLI1 or FLI1 but other ETS factors, which are very similar to FLI1 in terms of DNA binding site (PLoS One 2011). Here, we assessed the anti-proliferative activity of YK-4-279 in a panel of human cell lines derived from B- and T-cell lymphomas.
Methods. 48 cell lines [27 derived from DLBCL, 10 from mantle cell lymphoma (MCL), 3 from splenic marginal zone lymphoma (SMZL), 8 from anaplastic large cell lymphoma (ALCL)] were treated with increasing doses of YK-4-279) and IC50s were calculated with the MTT assays after 72 hrs exposure. Baseline gene expression profiling (GEP) was obtained on the cell lines with the Illumina HumanHT-12 Expression BeadChips and integrated with the anti-proliferative effect.
Results. YK-4-279 showed potent dose-dependent anti-proliferative activity in most of the cell lines tested, with the majority of IC50 values being below 1000 nM. The median IC50 value was 393 nM (95% C.I., 272 - 3622 nM). There were no apparent differences among the different lymphoma subtypes: DLBCL (median IC50 = 386 nM; 95% C.I., 223-497), MCL (596 nM; 95% C.I., 230-1305), SMZL (217 nM; 95% C.I., 183-524) and ALCL (403 nM; 95% C.I., 170-3387). Results were confirmed by performing further MTT experiments using the R-YK-4-279 and S-YK-4-279, showing activity only when cells were exposed to the latter compound.
The comparison of baseline GEP between 14 less sensitive (IC50 &gt; 500 nM) and 9 highly sensitive (IC &lt; 200 nM) B-cell lines highlighted that the expression signature of the latter group was enriched of E2F1 and PAX5 targets (including FLI1), genes involved in germinal center, cell cycle, sequence-specific DNA binding, and RNA processing. Conversely, the low sensitivity was associated with NFKB-related genes. Genes such as BCL6, BACH2, LMO2, CXCR4 and FAK were among the 50 most up-regulated transcripts in the sensitive cells.
Conclusion. YK-4-279 shows strong anti-proliferative activity in lymphomas. Its activity appears positively correlated with the presence of germinal center B cell-related expression signatures and negatively with NFKB activity. The compound appears worth of further investigations in the lymphoma setting.
Citation Format: Elain YL Chung, Valdemar Priebe, Eugenio Gaudio, Ivo Kwee, Chiara Tarantelli, Andrea Rinaldi, Laura Carrassa, Monica Testoni, Luciano Cascione, Massimo Broggini, Jeffrey A. Toretsky, Emanuele Zucca, Francesco Bertoni. The small molecule YK-4-279 shows anti-lymphoma activity in pre-clinical models. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1654. doi:10.1158/1538-7445.AM2015-1654