STEAP1-specific T cells for immunotherapy of Ewing sarcoma

Primary metastatic Ewing sarcoma involving the bone and/or bone marrow has remained largely incurable. We propose to use cytotoxic T cells (CTLs) specific for STEAP-1, a surface protein aberrantly expressed in Ewing sarcoma, as therapeutic tools to eradicate minimal residual disease and prevent tumor dissemination and relapse. STEAP-1-specific CTLs were successfully expanded from purified CD8+ T cells from 6 HLA-A2-positive healthy donors by stimulation with autologous dendritic cells pulsed with a pool of 4 STEAP-1 peptides (5µM each) in the presence of rhIL-7, rhIL-12 and rhIL-15. Weekly restimulations were pe…