MHC Class I-Restricted TCR-Transgenic CD4+ T Cells Against STEAP1 Mediate Local Tumor Control of Ewing Sarcoma In Vivo

Abstract

<jats:p>In this study we report the functional comparison of T cell receptor (TCR)-engineered major histocompatibility complex (MHC) class I-restricted CD4+ versus CD8+ T cells targeting a peptide from six transmembrane epithelial antigen of the prostate 1 (STEAP1) in the context of HLA-A*02:01. STEAP1 is a tumor-associated antigen, which is overexpressed in many cancers, including Ewing sarcoma (EwS). Based on previous observations, we postulated strong antitumor potential of tumor-redirected CD4+ T cells transduced with an HLA class I-restricted TCR against a STEAP1-derived peptide. We compared CD4+ T cell populations to their CD8+ counterparts in vitro using impedance-based xCELLigence and cytokine/granzyme release assays. We further compared antitumor activity of STEAP130-TCR transgenic (tg) CD4+ versus CD8+ T cells in tumor-bearing xenografted Rag2−/−γc−/− mice. TCR tgCD4+ T cells showed increased cytotoxic features over time with similar functional avidity compared to tgCD8+ cells after 5–6 weeks of culture. In vivo, local tumor control was equal. Assessing metastatic organotropism of intraveniously (i.v.) injected tumors, only tgCD8+ cells were associated with reduced metastases. In this analysis, EwS-redirected tgCD4+ T cells contribute to local tumor control, but fail to control metastatic outgrowth in a model of xenografted EwS.</jats:p>

Ewing Sarcoma-Derived Extracellular Vesicles Impair Dendritic Cell Maturation and Function

“…Cytokines and chemokines in conditioned medium from cell cultures were analyzed using the Bio-Plex Pro Human Chemokine TNF-α Set (171BK55MR2) and Bio-Plex Human Cytokine Screening Panel, 48-plex panel (both Bio-Rad, Munich, Germany) as described previously [34]. Conditioned medium was collected, centrifuged at 2000× g for 10 min at 4 • C, and stored at −80 • C until further analysis.…”

“…Phenotypes of myeloid and T cells were assessed by flow cytometry as previously reported [30,34]. Briefly, CD14 + and CD33 + moDCs were stained with anti-CD14 (REA599), CD33 (REA775), CD80 (REA661), CD83 (REA714), CD86 (REA968), HLA-DR (REA805) and respective isotype (IT) antibodies.…”

Enhanced Stability of Detergent-Free Human Native STEAP1 Protein from Neoplastic Prostate Cancer Cells upon an Innovative Isolation Procedure

“…Indeed, several studies with monoclonal antibodies attached to radioisotopes have demonstrated promising results in targeting and monitoring STEAP1 expression and in controlling PCa progression [ 11 , 12 ]. Likewise, several in vitro and in vivo studies revealed that STEAP1-derived peptides are immunogenic and hence suitable for recognition by cytotoxic T lymphocytes [ 13 , 14 ], suggesting their potential use in the development of anti-cancer vaccines. Altogether, these features highlight the usefulness of STEAP1 as a promising tool, either as a biomarker or as a target for anti-cancer therapies [ 15 , 16 ].…”

The Usefulness of STEAP Proteins in Prostate Cancer Clinical Practice

“…These structural features highlight the usefulness of STEAP1 as a promising therapeutic target and biomarker for cancer and encouraged the development of strategies targeting STEAP1. In vitro and in vivo studies revealed mobilized dendritic cells and immunogenic STEAP1-derived peptides suitable for recognition by cytotoxic T lymphocytes for further development of anti-cancer vaccines (23). Humanized variant of anti-STEAP1 monoclonal antibody (mAb 120.545) is currently used in prostate cancer clinical trials as an antibody-drug conjugate (DSTP3086S) (24), and as a radiolabeled antibody (89Zr-DFO-MSTP2109A) for PET imaging (24,25).…”