4-1BB-based Isolation and Expansion of CD8⁺ T Cells Specific for Self-Tumor and Non–Self-Tumor Antigens for Adoptive T-cell Therapy

Abstract

Adoptive T-cell therapy is a promising approach to the immunotherapy of cancer, but for it to be a general cancer therapy a simple and standardized procedure for producing tumor-specific CD8⁺ T cells is needed. On the basis of a unique property of 4-1BB (CD137), the selective expression on activated T cells, we have developed a simple and practical protocol to produce antigen-specific CD8⁺ T cells from peripheral blood mononuclear cells. We have proved the feasibility of this procedure by isolating and expanding cytomegalovirus-specific CD8⁺ T cells, and applied the procedure to produce Epstein-Barr virus (EBV)-specific CD8⁺ T cells. By using this procedure, we could readily produce 10⁹–10¹⁰ antigen-specific CD8⁺ T cells from 30 to 50 mL of blood in about 4 weeks. Moreover, our protocol allowed us to produce, from solid cancer patients, CD8⁺ T cells that were specific for self/tumor antigens such as human telomerase reverse transcriptase (hTERT). It is interesting to note that, we were unable to amplify hTERT-specific CD8⁺ T cells from healthy donors. Our protocol can be readily translated into cGMP-compliant production and is currently being used to produce EBV-specific CD8⁺ T cells for phase I clinical trial. We believe that our method will provide a practical and effective option for adoptive T-cell therapy in the clinic.