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Supplementary Figure S3 from Trabectedin Efficacy in Ewing Sarcoma Is Greatly Increased by Combination with Anti-IGF Signaling Agents

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posted on 2023-03-31, 18:49 authored by Ana Teresa Amaral, Cecilia Garofalo, Roberta Frapolli, Maria Cristina Manara, Caterina Mancarella, Sarah Uboldi, Silvana Di Giandomenico, Jose Luis Ordóñez, Victoria Sevillano, Roberta Malaguarnera, Piero Picci, A. Bass Hassan, Enrique De Alava, Maurizio D'Incalci, Katia Scotlandi

Supplementary Figure S3. Modulation of IGF-1R expression after transient silencing of EWS-FLI1 in EWS.

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ARTICLE ABSTRACT

Purpose: Goal of this study was to identify mechanisms that limit efficacy of trabectedin (ET-743, Yondelis) in Ewing sarcoma (EWS), so as to develop a clinical applicable combination therapy.Experimental Design: By chromatin immunoprecipitation, we analyzed EWS–FLI1 binding to the promoters of several target genes, such as TGFβR2, CD99, insulin-like growth factor receptor 1 (IGF1R), and IGF1, both in vitro and in xenografts treated with trabectedin or doxorubicin. Combined therapy with trabectedin and anti-IGF1R agents (AVE1642 HAb; OSI-906) was tested in vitro and in xenografts.Results: We confirm that both trabectedin and doxorubicin were able to strongly reduce EWS–FLI1 (both type I and type II) binding to two representative target genes (TGFβR2 and CD99), both in vitro and in xenografts. However, trabectedin, but not doxorubicin, was also able to increase the occupancy of EWS–FLI1 to IGF1R promoters, leading to IGF1R upregulation. Inhibition of IGF1R either by the specific AVE1642 human antibody or by the dual IGF1R/insulin receptor inhibitor OSI-906 (Linsitinib) greatly potentiate the efficacy of trabectedin in the 13 EWS cell lines here considered as well as in TC-71 and 6647 xenografts. Combined therapy induced synergistic cytotoxic effects. Trabectedin and OSI-906 deliver complementary messages that likely converge on DNA-damage response and repair pathways.Conclusions: We showed that trabectedin may not only inhibit but also enhance the binding of EWS–FLI1 to certain target genes, leading to upregulation of IGF1R. We here provide the rationale for combining trabectedin to anti-IGF1R inhibitors. Clin Cancer Res; 21(6); 1373–82. ©2015 AACR.