Abstract 2554: To clone tumor-specific TCRs from a cell-based immunotherapy-benefit cervical cancer patient

Abstract

Abstract Adoptive transfer of tumor-specific T cell receptor (TCR)-engineered T cells, TCR-T therapy, has shown great efficacy in clinical trials against solid tumors. A cervical cancer patient with bone metastasis was treated with a cell-based immunotherapy, named Multiple-Antigens Stimulating Cellular Therapy (MASCT), which is a combination of multiple tumor antigen peptides loaded dendritic cells (DCs) and autologous T cells stimulated by these DCs. After repeated treatment, the patient showed partially response and remained stable disease for 20 months. Moreover, boosted specific immune responses were detected in patient's periphery blood by IFNγ-Elispot assay against various tumor antigens, such as CEA, RGS5 and HPV18/58. The clinical benefits of this patient indicated that tumor-specific T cells were expanded in vivo and played an important role to control tumor progression. These T cells may be the good sources to isolate tumor-specific TCRs for TCR-T therapies. Given that, patient's PBMCs were stimulated in vitro with selected tumor peptides respectively, such as CEA, RGS5 and HPV18 E7. Tumor-specific T cells were defined as IFNγ-secreting T cells upon peptide stimulation and were further enriched by using magnetic beads. Part of the enriched T cells were analyzed for TCR alpha/beta repertoire via NGS, the other part were sorted into single T cells and analyzed for TCR alpha/beta pairing. The TCR repertoire NGS data revealed that the tumor-specific T cells harbor several hundred unique TCR alpha/beta clonotypes. Some unique TCR alpha/beta clonotypes were considered as tumor-specific TCR candidates, since the copy numbersof these clonotypes were significantly and repeatedly increased after stimulation with CEA, RGS5 or HPV18 E7, and further increased after IFNγ enrichment. After TCR alpha/beta pairing confirmation by single T cell sequencing, alpha and beta chains of these TCRs were sent to synthesis for further investigation. In conclusion we have successfully identified specific TCR clonotypes targeting selected tumor antigens from a MASCT-benefited cervical cancer patient. After functional validations, including epitope specificity, HLA restriction as well as tumor recognition, these tumor-specific TCRs may be good candidates for developing safer and more effective TCR-T therapy targeting multiple tumor antigens. Citation Format: Xiaoling Liang, Shudan Ou, Minjun Ma, Xihe Chen, Xiangjun Zhou, Yanyan Han. To clone tumor-specific TCRs from a cell-based immunotherapy-benefit cervical cancer patient [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2554.