Retrovirus-based manufacturing of chimeric antigen receptor-modified T cells for cancer therapy research

Treatment with autologous chimeric antigen receptor (CAR)-modified T cells can achieve outstanding clinical response rates in heavily pretreated patients with B and plasma cell malignancies. However, relapses occur, and they limit the efficacy of this promising treatment approach. The complex GMP-compliant production and high treatment costs cause that CAR T cells cannot yet be used in a broad population. Among others, CAR T cell therapy has evolved regarding vector design and manufacturing process. Optimal production of CAR T cells is not yet defined, far from being standardized. Quality, cellular composition and immunophenotype of the administered CAR T cells are influenced by the manufacturing protocol and therefore play a crucial role for therapeutic success. For the gene transfer, viral and non-viral strategies are available. Retrovirus-based protocols for CAR T cell production offer advantages in terms of stable gene integration, sufficient transduction efficiency, proven clinical success, and scalability. Here, we detail a retrovirus-based generation protocol of human CAR-modified T cells for experimental immunotherapeutic treatment of cancer cells. For the CAR generation, HEK-293-based packaging cell lines, CD3⁺ selection, CD3/CD28-coated bead-based activation and IL-2/IL-15-mediated expansion were used. This protocol can be applied for every possible CAR construct after being successfully transfected in HEK-293-based packaging cell lines.