Trabectedin efficacy in Ewing sarcoma is greatly increased by combination with anti-IGF signaling agents

• Published in: Clinical cancer research 2015-03, Vol.21 (6), p.1373-1382
• Main Authors: Amaral, Ana Teresa, Garofalo, Cecilia, Frapolli, Roberta, Manara, Maria Cristina, Mancarella, Caterina, Uboldi, Sarah, Di Giandomenico, Silvana, Ordóñez, Jose Luis, Sevillano, Victoria, Malaguarnera, Roberta, Picci, Piero, Hassan, A Bass, De Alava, Enrique, D'Incalci, Maurizio, Scotlandi, Katia
• Format: Article
• Language: English
• Subjects: 12E7 Antigen; Animals; Antigens, CD - genetics; Antineoplastic Agents, Alkylating - pharmacology; Antineoplastic Combined Chemotherapy Protocols - pharmacology; Caspase 3 - metabolism; Caspase 7 - metabolism; Cell Line, Tumor; Dioxoles - pharmacology; DNA Damage - drug effects; DNA Damage - genetics; DNA Repair - drug effects; DNA Repair - genetics; DNA-Binding Proteins - metabolism; Doxorubicin - pharmacology; Female; Humans; Imidazoles - pharmacology; Insulin-Like Growth Factor I - antagonists & inhibitors; Mice; Mice, Nude; Promoter Regions, Genetic - genetics; Protein Serine-Threonine Kinases - antagonists & inhibitors; Protein Serine-Threonine Kinases - genetics; Proto-Oncogene Protein c-fli-1 - metabolism; Pyrazines - pharmacology; Receptor, IGF Type 1 - antagonists & inhibitors; Receptor, IGF Type 1 - biosynthesis; Receptor, IGF Type 1 - genetics; Receptor, Transforming Growth Factor-beta Type II; Receptors, Transforming Growth Factor beta - antagonists & inhibitors; Receptors, Transforming Growth Factor beta - genetics; Sarcoma, Ewing - drug therapy; Tetrahydroisoquinolines - pharmacology; Trabectedin
• ISSN: 1078-0432; 1557-3265
• DOI: 10.1158/1078-0432.CCR-14-1688

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. 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. 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. 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.