Abstract 649: Emigrant pre-REP tumor infiltrating lymphocytes profoundly differ from remnant T-cells

Abstract

Abstract Adoptive T cell therapy with autologous tumor infiltrating lymphocytes (TIL) provides up to 56% objective response rates and a complete response in 24% of patients with metastatic melanoma. The process of generating TIL from resected tumor involves morcellating the tumor into 1-3 mm3 fragments and expanding TIL in the presence of Interleukin 2 (IL-2) in a pre-Rapid Expansion Protocol (pre-REP). During the ‘pre-REP’, tumor-resident immune cells emigrate (eTIL) and proliferate. The length of the pre-REP varies between 11-21 days, depending on cell growth. Residual tumor fragments (remnants) are discarded and the expanded eTIL are subjected to a Rapid Expansion Protocol (REP) with irradiated PBMC feeders, anti-CD3 and IL-2. Viable cells remaining in the tumor remnants (rTIL) following the pre-REP were investigated to assess their function and phenotype. We evaluated and compared the rTIL and eTIL in melanoma, breast, renal, pancreatic, lung and colorectal tumors (n=9). Tumor rTIL are consistently phenotypically distinct from eTIL, as determined by differential expression of various markers (Table 1). The fundamental differences in rTIL were: Increased CD69+ (7 fold MFI in CD4+) (p<.001); diminished LAG3 (2 fold MFI in CD8) (p<.05); TIM3 (3 and 2 fold MFI in CD8 and CD4 respectively) (p<.05/.01); CD154 (3 fold MFI in CD4) (p<.01); and CD56 (5%) (p<.05). Surprisingly, a REP of rTIL and eTIL resulted in comparable expansion. The phenotypic signature of TIL was sustained post-REP with fidelity of the individual expression of LAG3, Tim3, and CD28. These studies have identified significant differences in the biology of cell populations in terms of tissue-resident T cells and the signals associated with emigration and retention. These data provide additional insights on the individual TIL populations that could be utilized for adoptive T-cell therapy in patients and raise important questions about the nature of tissue-resident T cells in sites of chronic inflammation such as tumor. Table 1:Tumor resident remnant T cells are phenotypically distinct from emigrating T cells (N=9)Marker ExpressionLAG3 (CD8/ CD4) MFITim3 (CD8/ CD4) MFIPD-1 (CD8/ CD4) %CD69 (CD8/ CD4) MFICD154 (CD8/ CD4) MFICD28 (CD8/ CD4) MFICD57 (CD8/ CD4) %CD56%eTIL507/ 1442832/ 175636.95/ 471320/ 15431498/ 37511163/ 503618.76/ 19.65.615rTIL209/ 106877/ 74242.8/ 483437/ 223.41034/ 1167458.3/ 27959.16/8.51.027*P-values(CD8/ CD4) 0.05/ 0.210.05/ 0.010.38/ 0.890.11/ 0.0010.55/ 0.010.05/ 0.110.05/ 0.060.05 _______ Citation Format: Michelle R. Simpson-Abelson, Christopher Mosychuk, Maria Fardis, Michael T. Lotze. Emigrant pre-REP tumor infiltrating lymphocytes profoundly differ from remnant T-cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 649. doi:10.1158/1538-7445.AM2017-649