T cell receptor β‐chain repertoire analysis of tumor‐infiltrating lymphocytes in pancreatic cancer

Abstract

Pancreatic cancer is lethal due to lack of perceptible symptoms and effective treatment methods. Immunotherapy may provide promising therapeutic choices for malignant tumors like pancreatic cancer. Tumor‐infiltrating lymphocytes (TIL) in tumor mesenchyme could recognize peptide antigens presented on the surface of tumor cells. The present study aimed to test the relationship between the T cell receptor (TCR) β repertoire of the tumor and peripheral blood, and also to investigate the intra‐tumor spatial heterogeneity of the TCR β repertoire in pancreatic cancer. To the best of our knowledge, this is the first study to evaluate the clonal composition of TCR β repertoire in TIL across the spatial extent of pancreatic cancer. In this study, we studied 5 patients who were diagnosed with primary pancreatic cancer. Ultra‐deep sequencing was used to assess the rearrangement of the TCR β‐chain (TCR β) gene. HE staining and immunohistochemistry of CD3, CD4, CD8 and HLA class I were used to show histopathology and immune conditions macroscopically. TIL repertoire showed that different regions of the same tumor showed a greater number of repertoire overlaps between each other than between peripheral blood, which suggested that T cell clones in pancreatic cancer might be quite different from those in peripheral blood. In contrast, intra‐tumoral TCR β repertoires were spatially homogeneous between different regions of a single tumor tissue. Based on these results, we speculated that the cellular adaptive immune response in pancreatic cancer was spatially homogeneous; this may pave the way for immunotherapy for the treatment of pancreatic cancer patients.

Comprehensive immune characterization and T‐cell receptor repertoire heterogeneity of retroperitoneal liposarcoma

“…Despite the infiltration of TILs and potential subtypes that could benefit from immunotherapy, TCR CDR3 sequencing suggested low T cell infiltration in RLPS patients compared with previous studies. Both the productive TCR β reads and the unique TCR β reads of RLPS specimens were lower than those in corresponding peripheral blood samples and other tumors . Low productive reads were associated with less T cell infiltration, which can be confirmed by IHC results.…”

“…In addition, although the intratumoral TCR repertoires were less heterogeneous than the differences between tumor and blood, the median pairwise intratumoral TCR repertoires overlap was 0.38, and only 35 of 125 pairwise overlaps were 0.5 or higher. These results suggested a larger heterogeneity in RLPS than in other tumors . Analyses of TCR repertoires showed that ubiquitous sequences were rare across different sites of a single tumor, which also indicated a great spatial heterogeneity within RLPS.…”

“…We also compared the TCR repertoire of RLPS with that in studies of pancreatic cancer and ESCC . As shown in Figure , the average productive reads of RLPS were significantly lower than that of pancreatic cancer (192 675 ± 209 295 vs 2 093 023 ± 685 896; P < .001) and ESCC (192 675 ± 209 295 vs 1 307 119 ± 719 871; P < .001), and the average unique reads of RLPS were 12 276 ± 12 237, which was also significantly lower than that in pancreatic cancer (15 646 ± 5984; P = .0016) and ESCC (112 833 ± 53 982; P < .001).…”

“…To compare TCR repertoire overlap between 2 specimens, Jaccard similarity coefficient as used and then transformed into a distance value using: . A distance‐based neighbor joining algorithm in MEGA (version 7.0) was used to draw a phylogenic tree in accordance with previous studies …”

“…Therefore, TCRs represent various subclones of antigen‐specific T cells . Previous studies of ovarian and pancreatic cancers assessed multisite samples of a single tumor using TCR β CDR3 sequencing and the results suggested that the composition of TCR repertoires was homogenous . However, in hepatocellular carcinoma, lung adenocarcinoma, and esophageal squamous cell carcinoma (ESCC), TCR repertoires were heterogeneous .…”