5613423 TREATMENT OF ERYTHROID PRECURSOR CELLS FROM β-THALASSEMIC PATIENTS WITH ISOXAZOLE DERIVATIVES: POTENT INDUCTION OF FETAL HEMOGLOBIN

Abstract

Background: Increased production of fetal hemoglobin (HbF) can be beneficial for β-thalassemia patients and several clinical trials in β-thalassemia and/or sickle-cell disease (SCD) are ongoing using HbF inducers, such as NCT01245179 (based on the HDAC inhibitor Panobinostat), NCT00790127 (based on 2,2-dimethylbutyrate, HQK-1001) and NCT03877809 (based on the mTOR inhibitor sirolimus). Methods: In this context, new molecules able to induce HbF are needed. In this communication, we have studied in deep a new class of promising HbF inducers characterized by an isoxazole chemical skeleton. These derivatives are 3,4-isoxazolediamide compounds recently synthesized in our laboratories. The original structures of two natural molecules, geldanamycin and radicicol, known to be natural Hsp (Heat Shot Protein) inhibitors, were modified to lead to a novel class of synthetic compounds, containing the isoxazole nucleus, and displaying potent and selective inhibition of Hsp90. Here we used erythroid precursors cells (ErPCs) isolated from β-thalassemic patients and treated with appropriate concentrations of 8 isoxazole derivatives previously demonstrated to be able to induce erythroid differentiation of K562 cells. Results: We demonstrated the high efficacy of the analyzed isoxazoles in inducing HbF. Some derivatives demonstrated an activity even higher than other HbF inducers used as positive controls, such as Hydroxyurea (HU) or Sirolimus. Most of the isoxazole derivatives displayed high effects in decreasing the excess of free α-globin chains in treated ErPCs. All the compounds were assayed for genotoxicity through the Ames test, employing the histidine-requiring Salmonella typhimurium mutant TA 97A, TA98, TA100 and TA1535 strains that allow to check frameshift mutation and base-pair substitution, with and without metabolic activation induced by S9 Mix. These assays excluded any drawbacks related to genotoxicity. Summary - Conclusion: We may therefore conclude that these novel isoxazoles could be proposed for clinical studies for possible therapeutic application for the treatment of β-thalassemia. These compounds have been recently patented as potential therapeutic agents for β-thalassemia (US Patent 11077116). Acknowledgements This study was sustained by the Wellcome Trust (innovator award 208872/Z/17/Z), by AIFA (AIFA-2016-02364887) and by the UE THALAMOSS Project (Thalassemia Modular Stratification System for Personalized Therapy of Βeta-Thalassemia; no. 306201-FP7-HEALTH-2012-INNOVATION-1). We thank A.L.T. (Associazione per la lotta alla Talassemia) “Rino Vullo” - Ferrara, and A.V.L.T. (Associazione Veneta per la Lotta alla Talassemia) “Elio Zago” - APS – Rovigo.