CTIM-16. DEVELOPING PATIENT SPECIFIC TUMOR INFILTRATING LYMPHOCYTES (TILS) WITH INCREASED TUMOR SPECIFICITY AS A THERAPY FOR GLIOBLASTOMA

Abstract

Abstract Immunotherapy failure in glioblastoma results from three main hurdles; limited numbers of T cells within the tumor, T cell exhaustion and significant intra-tumoral and intra-patient heterogeneity leading to lack of T cell tumor recognition. Our group has developed an expansion protocol to isolate and expand less exhausted tumor infiltrating lymphocytes (TILs) from the tumor periphery, selecting for TILs that recognize tumor antigen ex vivo. This process will increase the number of T-cells specific for an individual patient’s diverse tumor neoantigens. We have successfully expanded glioblastoma associated TILs from 66% of the novel Lukens trap substrate, which collects TILs and tumor from the tumor periphery. Cells are expanded in two stages, preREP and REP, through novel methods based on a protocol with clinical success in lung cancer and modified to increase the percent of tumor specific T cells. Through co-culture with patient matched glioma neurospheres we have identified activated T cells from each stage of culture (initial product, preREP, REP) based on CD137+ expression and tumor specific cytokine release (IFNy+TNFa+IL2+IL17a+) by flow cytometry. Through 5’scRNA sequencing paired with TCR repertoire analysis we can identify activation specific TCRs. Overrepresented TCR alpha and beta chains will be linked by a P2A site, cloned into a lentiviral vector, and transduced into TCR negative Jurkat cells to confirm tumor reactivity. This strategy will allow us to enrich and assess tumor specific TCR activity compared to bystander activation in our TIL product. Following additional preclinical assessment of cytotoxicity against autologous tumor, we will evaluate safety and feasibility of by administering our novel TIL product intrathecally in patients with glioblastoma.