385 Identification and enrichment of neoantigen-reactive T cells to optimize adoptive cell transfer with tumor-infiltrating lymphocytes (TIL)

Background Adoptive cell transfer (ACT) using tumor-infiltrating lymphocytes (TIL) has achieved an overall response rate of 39% in metastatic melanoma patients at Moffitt Cancer Center. In these trials, a substantial fraction were non-responders by RECIST, but demonstrated mixed to therapy. These results suggest that the infused TIL product contained tumor-reactive T cells with therapeutic potential, which could be further optimized improve ACT TIL. We hypothesized outcomes might improved identifying and enriching neoantigen-reactive within bulk products. The purpose this study is define approaches optimize TIL, identifying, enriching, analyzing neoantigen reactive from infusion previously treated patients. Methods Patient-derived cryopreserved tumor tissue, PBMC, completed trials used for study. Whole exome RNA sequencing performed on DNA extracted tissue compared autologous PBMC. Genetic gene expression data utilized determine protein-modifying somatic mutations. Peptides then predicted their ability presented MHC molecules, prioritized, up 192 custom 25-mers synthesized per patient sample. Neoantigen peptides loaded onto patient-derived dendritic (DC) co-cultured sorted FACS upregulate 41BB OX40 expanded through rapid expansion protocol (REP). Enriched subsequently screened reactivity 41BB/OX40 upregulation, cytokine release, degranulation. Results Protein-altering mutations tissues ranged 49 1631 (median = 389). On average, 16.2% upregulation upon co-culture DC pulsed peptide pool (range: 2.7–31.1%). CD4+ displayed 3.75-fold 41BB/OX40, while CD8+ saw 1.88-fold increase (n=6). This coincided production IFNγ, TNFα, granzyme B Neoantigen-reactive (41BB+/OX40+) non-reactive (41BB-/OX40-) similar degrees REP (average 639-fold vs. 611-fold; n=6). Restimulation enriched neoantigen-specific resulted superior pro-inflammatory functionality (granzyme B, TNFα) when Conclusions samples successfully maintained increased against restimulation support investigation into use neoantigen-enriched products enhance efficacy ACT. Trial Registration NCT01005745, NCT01659151 , NCT01701674 Ethics Approval NCT01005745 was approved USF IRB approval number Ame5_107905. Advarra 14.03.0083. Ame13_Pro00009061.All participants gave informed consent before taking part.