Distinct Stromal and Immune Features Collectively Contribute to Long-Term Survival in Pancreatic Cancer

Abstract

Background: The aggressive biology and treatment refractory nature of pancreatic ductal adenocarcinoma (PDAC) significantly limits long-term survival. Examining the tumor microenvironment (TME) of long-term survivors (LTS) of PDAC offers the potential of unveiling novel biological insights and therapeutic targets.Methods: We performed an integrated approach involving immunophenotyping, stromal scoring and histomorphological profiling of a cohort of 112 PDAC-cases, including 25 long-term survivors (LTSs, OS ≥ 60 months). Mutational frequencies were assessed using targeted next generation sequencing. Finally, we validated our findings in silico using an external cohort of microarray data from PDAC patients.Results: LTS cases exhibit a largely quiescent population of cancer-associated fibroblasts (CAFs). Immune profiling revealed key differences between LTS and NON-LTS cases in the intratumoral and stromal compartments. In both compartments, LTS cases exhibit a T cell inflamed profile with higher density of CD3+ T cells, CD4+ T cells, iNOS+ leukocytes and strikingly diminished numbers of CD68+ total macrophages, CD163+ (M2) macrophages and FOXP3+ Tregs. A large proportion of LTS cases exhibited tertiary lymphoid tissue (TLT) formation, which has been observed to be a positive prognostic marker in a number of tumor types. Using a Random-Forest variable selection approach, we identified the density of stromal iNOS+ cells and CD68+ cells as strong positive and negative prognostic variables, respectively. In an external cohort, computational cell-type deconvolution revealed a higher abundance of T cells, B lymphocytes and dendritic cells (DCs) in patients with long-term OS compared to short-term survivors. Thus, in silico profiling of long-term survivors in an external cohort, strongly corroborated the T cell-inflamed TME observed in our LTS group.Conclusions: Collectively, our findings highlight the prognostic importance of TME profiles in PDAC, underlining the crucial role of tumor associated macrophages (TAMs) and the potential interdependence between immunosuppressive TAMs and activated CAFs in pancreatic cancer. Additionally, our data has potential for precision medicine and patient stratification. Patients with a T cell inflamed TME might derive benefit from agonistic T cell antibodies (e.g., OX40 or CD137 agonists). Alternately, patients with activated CAFs and high infiltration of immunosuppressive TAMs are highly likely to exhibit therapeutic responses to macrophage targeted drugs (e.g., anti-CSF1R) and anti-CAF agents.

Prognostic Implications of Intratumoral and Peritumoral Infiltrating Lymphocytes in Pancreatic Ductal Adenocarcinoma

“…TILs can be a valuable parameter in daily practice because the assessment is possible in various pathologic examinations, such as endoscopic ultrasonography-fine needle aspiration cytology. The clinical implications of TILs in pancreatic cancers have been reported [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]; however, various parameters have also been introduced for TILs in pancreatic cancers. Moreover, cumulative information for these varying TILs cannot be obtained from previous reports [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ].…”

“…The clinical implications of TILs in pancreatic cancers have been reported [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]; however, various parameters have also been introduced for TILs in pancreatic cancers. Moreover, cumulative information for these varying TILs cannot be obtained from previous reports [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. Hence, we studied the prognostic implications of various TIL markers and performed a detailed subgroup analysis of intra- and peritumoral T lymphocytes in PDACs through a meta-analysis.…”

“…In the present study, we also evaluated the prognostic role of peritumoral lymphocytes. Peritumoral infiltrating lymphocytes were evaluated using CD3 and CD8 markers [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. There was no significant correlation between peritumoral infiltrating lymphocytes and PDAC prognosis.…”

“…For the meta-analysis, data were obtained from 20 eligible studies [ 4 , 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 ]. The extracted data included the author’s information, study location, number of patients analyzed, markers for TILs in PDAC, and the correlation between TIL markers and PDAC survival.…”

Nanomedicine in Pancreatic Cancer: Current Status and Future Opportunities for Overcoming Therapy Resistance

“…Although the purpose of PEG removal in this study was to expose an underlying RGD targeting motif for improved internalisation by tumour cells, the same principles could be applied to unmask M1-polarising nanoparticles in the pancreatic stroma and promote their engulfment by macrophages. Continued efforts to harness the unique capabilities of nanotechnology to re-educate macrophages will form an important future research direction, given that M2-like programming is a poor prognostic indicator in PaCa patients [ 181 , 182 , 183 , 184 ].…”