Utilizing IL-7 to generate melanoma antigen T cell receptor-modified cells for adoptive transfer in the absence of activation.

Abstract

e14552 Background: Metastatic melanoma remains a fatal disease as many patients fail to respond to novel therapies. Presently, we have an ongoing trial utilizing T cell receptor (TCR)-modified cells reactive to the melanoma antigen, tyrosinase, for treatment of metastatic melanoma (NCT01586403). Current protocols using viral vectors to generate cells for adoptive transfer require activation in the presence of IL-2. While IL-2 stimulates proliferation and production of mature effector cells, it also induces T cell exhaustion. We hypothesize that tyrosinase-reactive TCR-modified cells generated in the absence of activation have an increased potential for expansion, persistence, and anti-melanoma activity. In these studies, we investigate whether IL-7, a homeostatic regulator, facilitates the transfer of a tyrosinase-reactive TCR to lymphocytes without activation. Methods: Gene-modified cells were generated using a lentiviral vector including alpha and beta chains of a TCR reactive to tyrosinase and a truncated CD34 molecule as a transduction marker. Peripheral lymphocytes from normal human donors were transduced with lentivirus following no treatment, treatment with IL-7, or activation in the presence of IL-2. Transduced CD34 positive cells were isolated using magnetic activated cell sorting (MACS) and injected intravenously into NOD scid gamma (NSG) mice. Results: We found that IL-7 treatment improved transduction in non-activated cells and resulted in expression levels of CD34 and TCR variable beta chain 12 (vbeta12) comparable to cells activated in the presence of IL-2. When non-activated tyrosinase-reactive TCR-modified human T cells were adoptively transferred into NOD NSG mice, the cells were detectable in the peripheral blood of mice up to 7 days after transfer. Conclusions: These findings suggest that generating melanoma antigen TCR-modified cells in the absence of activation for adoptive transfer is feasible with IL-7 treatment. Ongoing studies in NSG mice transplanted with melanoma will help determine whether non-activated gene-modified cells will improve the efficacy and longevity of cell therapy for melanoma and other malignancies.