Abstract

Cyclin A1 is a promising antigen for T cell therapy being selectively expressed in high-grade ovarian cancer (OC) and acute myeloid leukemia (AML) stem cells. For adoptive T cell therapy, a single epitope has to be selected, with high affinity to MHC class I and adequate processing and presentation by malignant cells to trigger full activation of specific T cells. In silico prediction with three algorithms indicated 13 peptides of Cyclin A1 9 to 11 amino acids of length to have high affinity to HLA-A*02:01. Ten of them proved to be affine in an HLA stabilization assay using TAP-deficient T2 cells. Their immunogenicity was assessed by repetitive stimulation of CD8+ T cells from two healthy donors with single-peptide-pulsed dendritic cells or monocytes. Intracellular cytokine staining quantified the enrichment of peptide-specific functional T cells. Seven peptides were immunogenic, three of them against both donors. Specific cell lines were cloned and used in killing assays to demonstrate recognition of endogenous Cyclin A1 in the HLA-A*02:01-positive AML cell line THP-1. Immunopeptidome analysis based on direct isolation of HLA-presented peptides by mass spectrometry of primary AML and OC samples identified four naturally presented epitopes of Cyclin A1. The immunopeptidome of HeLa cells transfected with Cyclin A1 and HLA-A*02:01 revealed six Cyclin A1-derived HLA ligands. Epitope p410–420 showed high affinity to HLA-A*02:01 and immunogenicity in both donors. It proved to be naturally presented on primary AML blast and provoked spontaneous functional response of T cells from treatment naïve OC and, therefore, warrants further development for clinical application.

Highlights

  • Immunotherapy has been considered a revolution in the treatment of malignant diseases

  • We recently described Cyclin A1 as new gametopoiesis-associated cancer testis antigen, which is selectively expressed in acute myeloid leukemia (AML) including its stem cell compartment and ovarian cancer (OC) [11, 15]

  • peripheral blood mononuclear cells (PBMC) from two HLA-A*02:01-positive healthy donors were analyzed as control

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Summary

Introduction

Immunotherapy has been considered a revolution in the treatment of malignant diseases. Many translational scientists working on targeted T cell therapy have turned from vaccination based on peptides or dendritic cells to adoptive T cell therapy (ACT) approaches using autologous T cells. Cancer Immunology, Immunotherapy (2020) 69:1217–1227 transfected with high-affinity T cell receptors (TCR) against epitopes of tumor-associated antigens (TAA) in context of MHC class I molecules. ACT based on the transfection of patient T cells with a second high-affinity TAA-specific TCR is usually designed with an initial apheresis step followed by isolation, activation, and transfection of a predefined T cell subset. A defined number of transfected autologous T cells are transferred back into the patient, sometimes followed by application of IL2 to prolong persistence of the transfected T cells [5, 6]

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