T-Helper 1 Immune Response in Metastatic Lymph Nodes of Pancreatic Ductal Adenocarcinoma: A Marker For Prolonged Survival

Immunological effects of heated intraperitoneal chemotherapy can be augmented by thymosin α1

BACKGROUND

Peritoneal metastases of colorectal carcinoma origin (PM-CRC) are treated by cytoreductive surgery and heated intraperitoneal chemotherapy (HIPEC). However, the majority of patients recur, calling for novel treatments. We explored the immunogenic changes induced by HIPEC and the possibility to use thymosin α1 (Tα1) as an immune-stimulatory agent.

METHODS

We used an experimental murine model of PM-CRC combined with mitomycin (MMC)-based HIPEC. We determined immune cell infiltration into tumor metastases after HIPEC administration by means of immunohistochemistry, and determined immunogenic cell death signals in tumor cells by real-time polymerase chain reaction.

RESULTS

Mice with PM-CRC treated by HIPEC had increased overall survival (OS) compared to sham-treated mice (median OS 22.8 vs 18.9 days, respectively; P < 0.001). HIPEC induced increased infiltration of CD4+, CD8+, CD68 + and CD20 + cells into omental and visceral metastases at a magnitude of 40-100 %. We searched for potential immune signals induced by HIPEC by determining its effects on known immunogenic cell death proteins (heat-shock protein [HSP]-70, HSP-90 and calreticulin). HIPEC significantly increased HSP-90 mRNA expression (2.37 ± 1.5 vs 1-fold change, P < 0.05). The OS of Tα1 treated mice significantly improved compared to HIPEC-treated mice (16.3 ± 0.8 vs 14.1 ± 0.6 days, respectively, P = 0.02) and vs sham (11.8 ± 0.8 days, P = 0.007).

CONCLUSIONS

HIPEC induced immunogenic changes that led to increased immune cell infiltration. These changes were further augmented by Tα1 treatment. Future studies aimed at optimizing Tα1 treatment should focus upon the immune response it evokes.

PD-1 Blockade Combined with Heated Intraperitoneal Chemotherapy Improves Outcome in Experimental Peritoneal Metastases from Colonic Origin in a Murine Model

BACKGROUND

Heated intraperitoneal chemotherapy (HIPEC) was shown to induce immunogenicity of peritoneal metastases from colorectal cancer (PM-CRC) by induction of immunogenic cell death. We aimed to explore whether the addition of a checkpoint inhibitor would augment the effect of HIPEC in an experimental murine model of PM-CRC.

METHODS

PM-CRC was established in C57BL mice by intraperitoneal inoculation of MC38 colon cancer cells. HIPEC was administered using the closed technique with mitomycin C (MMC). Clinical and immunological parameters were compared between animals treated with HIPEC alone and those treated with HIPEC + anti-programmed death receptor-1 (aPD-1).

RESULTS

MMC-based HIPEC increased the overall survival of animals compared with sham-treated animals (22.8; 95% confidence interval [CI] 21.14-24.53 vs. 18.9 days; 95% CI 17.6-20.3, p < 0.001). The extent of peritoneal disease as measured by the modified peritoneal carcinomatosis index was also reduced by HIPEC. This clinical benefit was accompanied by increased infiltration of CD8⁺, CD68⁺, and CD20⁺ cells into tumor metastases in HIPEC-treated animals compared with sham-treated animals. We identified heat shock protein (HSP) 90 as a potential immunogenic cell death protein whose expression is increased under HIPEC conditions (fold change: 2.37 ± 1.5 vs. 1 without HIPEC, p < 0.05). Combined HIPEC + PD-1 treatment ameliorated survival compared with HIPEC alone and sham treatment (24.66; 95% CI 20.13-29.2 vs. 19; 95% CI 15.85-22.14 and 14.33 days; 95% CI 9.6-19.04, respectively; p = 0.008). This clinical effect was accompanied by increased CD8⁺ tumor infiltration.

CONCLUSIONS

HIPEC induced the expression of immunogenic cell death signals that can support an anti-tumor immune response. This response can be further exploited by a checkpoint inhibitor.

Thymosin alpha 1 as an adjuvant to hyperthermic intraperitoneal chemotherapy in an experimental model of peritoneal metastases from colonic carcinoma

INTRODUCTION

Heated intraperitoneal chemotherapy (HIPEC) is currently implemented in the treatment of peritoneal metastases from colorectal carcinoma (PM-CRC) origin. However, recurrence is common and the effectiveness of HIPEC has been questioned. The aim of this study was to evaluate the use of thymosin alpha 1 (Tα1), an immunomodulatory molecule, as an adjuvant to HIPEC treatment.

METHODS

We developed an experimental model of HIPEC by the induction of PM-CRC in C57BL mice and intra-abdominal perfusion of mitomycin C (MMC). Mice were treated with Tα1 at 0.6 mg/kg for 5 days after HIPEC. Clinical and immunological parameters were compared between HIPEC and HIPEC + Tα1 groups.

RESULTS

Treatment with Tα1 increased overall survival of mice compared to HIPEC treatment alone and sham-treated animals (16.1 ± 0.8 vs. 14.1 ± 0.6 and 11.8 ± 0.8, respectively, p = 0.02). Tα1 had no direct anti-tumor effect, as seen by lack of inhibition of tumor cell proliferation. Tα1 treatment induced a T helper (Th) 1 immune response in tumor metastases as evidenced by a significant increase of the Th1-specific markers IFN-γ and T-bet (1.21 ± 0.3 vs. 0.52 ± 0.08, p < 0.05; 0.88 ± 0.04 vs. 0.64 ± 0.14, p < 0.05, respectively). This Th1 skew was accompanied by increased CD8⁺ infiltration into omental and visceral metastases by Tα1 treatment compared to sham and HIPEC-treated animals (21.24 ± 2.16 vs. 10.45 ± 0.89 and 7.7 ± 1.3, p < 0.001; 14.12 ± 1.54 vs. 12.12 ± 0.01 and 6.64 ± 0.87, p < 0.01, respectively).

CONCLUSIONS

Tα1 augments the effect of HIPEC by the induction of a Th1 anti-tumor immune response. Further experiments should evaluate Tα1 and other novel immunomodulators in order to exploit the immunological opportunities created by HIPEC.

The Immune Landscape of Human Pancreatic Ductal Carcinoma: Key Players, Clinical Implications, and Challenges

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive and deadliest cancer worldwide with an overall survival rate, all stages combined, of still <10% at 5 years. The poor prognosis is attributed to challenges in early detection, a low opportunity for radical resection, limited response to chemotherapy, radiotherapy, and resistance to immune therapy. Moreover, pancreatic tumoral cells are surrounded by an abundant desmoplastic stroma, which is responsible for creating a mechanical barrier, preventing appropriate vascularization and leading to poor immune cell infiltration. Accumulated evidence suggests that PDAC is impaired with multiple “immune defects”, including a lack of high-quality effector cells (CD4, CD8 T cells, dendritic cells), barriers to effector cell infiltration due to that desmoplastic reaction, and a dominance of immune cells such as regulatory T cells, myeloid-derived suppressor cells, and M2 macrophages, resulting in an immunosuppressive tumor microenvironment (TME). Although recent studies have brought new insights into PDAC immune TME, its understanding remains not fully elucidated. Further studies are required for a better understanding of human PDAC immune TME, which might help to develop potent new therapeutic strategies by correcting these immune defects with the hope to unlock the resistance to (immune) therapy. In this review, we describe the main effector immune cells and immunosuppressive actors involved in human PDAC TME, as well as their implications as potential biomarkers and therapeutic targets.

Prkci Regulates Autophagy and Pancreatic Tumorigenesis in Mice

Protein kinase C iota (PKCι) functions as a bonafide human oncogene in lung and ovarian cancer and is required for KrasG12D-mediated lung cancer initiation and progression. PKCι expression is required for pancreatic cancer cell growth and maintenance of the transformed phenotype; however, nothing is known about the role of PKCι in pancreas development or pancreatic tumorigenesis. In this study, we investigated the effect of pancreas-specific ablation of PKCι expression on pancreatic cellular homeostasis, susceptibility to pancreatitis, and KrasG12D-mediated pancreatic cancer development. Knockout of pancreatic Prkci significantly increased pancreatic immune cell infiltration, acinar cell DNA damage, and apoptosis, but reduced sensitivity to caerulein-induced pancreatitis. Prkci-ablated pancreatic acinar cells exhibited P62 aggregation and a loss of autophagic vesicles. Loss of pancreatic Prkci promoted KrasG12D-mediated pancreatic intraepithelial neoplasia formation but blocked progression to adenocarcinoma, consistent with disruption of autophagy. Our results reveal a novel promotive role for PKCι in pancreatic epithelial cell autophagy and pancreatic cancer progression.

Single-cell RNA transcriptome reveals the intra-tumoral heterogeneity and regulators underlying tumor progression in metastatic pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is the most frequent and aggressive pancreatic tumor characterized by high metastatic risk and special tumor microenvironment. To comprehensively delineate the complex intra-tumoral heterogeneity and the underlying mechanism during metastatic lesions malignant progression, single-cell RNA sequencing (scRNA-seq) was employed. PCA and TSNE were used for dimensionality reduction analysis and cell clustering. Find All Markers function was used to calculate differential genes in each cluster, and Do Heatmap function was used to plot the distribution of differential genes in each cluster. GSVA was employed to assign pathway activity estimates to individual cells. Lineage trajectory progression was inferred by monocle. CNV status was inferred to compare the heterogeneity among patients and subtypes by infercnv. Ligand-receptor interactions were identified by CellPhoneDB, and regulons network of cells was analyzed by SCENIC. Through RNA-sequencing of 6236 individual cells from 5 liver metastatic PDAC lesions, 10 major cell clusters are identified by using unbiased clustering analysis of expression profiling and well-known cell markers. Cells with high CNV level were considered as malignant cells and pathway analyses were carried out to highlight intratumor heterogeneity in PDAC. Pseudotime trajectory analysis revealed that components of multiple tumor-related pathways and transcription factors (TFs) were differentially expressed along PDAC progression. The complex cellular communication suggested potential immunotherapeutic targets in PDAC. Regulon network identified multiple candidates for promising cell-specific transcriptional factors. Finally, metastatic-related genes expression levels and signaling pathways were validated in bulk RNA Sequencing data. This study contributed a comprehensive single-cell transcriptome atlas and contributed into novel insight of intratumor heterogeneity and molecular mechanism in metastatic PDAC.

Killing the "BAD": Challenges for immunotherapy in pancreatic cancer

Cancer regression often fails after systemic immune activation, especially for solid tumors due to their local immunosuppressive microenvironments. Among these, the pancreatic cancer microenvironment is unique and an important reason for resistance to anti-cancer treatments that include immunotherapy. In this review, the three main "BAD" characteristics that create and maintain this immunosuppressive microenvironment are discussed for effector T cells: Barriers to overcome, Attraction problems, and their Disabilities. These inhibit both effector T-cell activation and infiltration, reducing immunotherapy effectiveness. Combination approaches for killing the "BAD" aim to normalize the tumor microenvironment and are recommended to enhance anti-cancer immune-system efficacy in pancreatic cancer.

The prognostic value of tumour-infiltrating lymphocytes in pancreatic cancer: a systematic review and meta-analysis

IMPORTANCE

Tumour-infiltrating lymphocytes (TILs) have previously been found to influence patient prognosis in other gastrointestinal cancers, for instance in colorectal cancer. An immunosuppressive phenotype often characterizes pancreatic cancer with a low degree of immune cell infiltration. Cytotoxic CD8⁺ T cell infiltration in tumours is found to be the best predictive variable for response to immune checkpoint inhibitor therapy, emphasizing the importance of investigating TILs in pancreatic cancer, especially focussing on CD8⁺ T cells.

OBJECTIVE

Here, we systematically review the literature and perform meta-analyses to examine the prognostic value of TILs in human pancreatic ductal adenocarcinomas (PDAC). Secondarily, we review the literature regarding the histological localization of TILs and the impact on survival in PDAC.

EVIDENCE REVIEW

A literature search was conducted on PubMed, Embase, The Cochrane Library and Web of Science. Studies examining patients with PDAC and the impact of high vs. low infiltration of immune cells on long-term oncological survival measures were included. Time-to-event meta-analysis and frequency analysis were conducted using a random effects model. The risk of bias was assessed using the Newcastle-Ottowa Scale. Quality of the cumulative evidence was evaluated using the GRADE approach for prognostic studies.

FINDINGS

In total, 1971 articles were screened, of which 43 studies were included in the systematic review and 39 in the meta-analysis. High infiltration of CD8+ lymphocytes was significantly associated with improved overall survival (OS) [hazard ratio (HR) = 0.58, 95% confidence intervals (CIs): 0.50-0.68], disease-free survival (DFS) [HR = 0.64, 95% CI: 0.52-0.78], progression-free survival [HR = 0.66, 95% CI: 0.51-0.86] and cancer-specific survival [HR = 0.56, 95% CI: 0.32-0.99]. A high infiltration of CD3+ T cells was correlated with increased OS [HR = 0.58, 95% CI: 0.50-0.68] and DFS [HR = 0.74, 95% CI: 0.38-1.43]. Infiltration of CD4+ lymphocytes was associated with improved 12-months OS [risk ratio = 0.59, 95% CI: 0.35-0.99] and DFS [risk ratio = 0.68, 95% CI: 0.53-0.88]. High expression of FoxP3+ lymphocytes was associated with poor OS [HR = 1.48, 95% CI: 1.20-1.83]. The greatest impact on survival was observed in the CD8+ T cell and OS group, when infiltration was located to the tumour centre [HR = 0.53, 95% CI: 0.45-0.63]. However, subgroup analysis on the impact of the histological location of infiltration revealed no significant differences between the subgroups (tumour centre, invasive margin, stroma and all locations) in any of the examined cell types and outcomes.

CONCLUSIONS AND RELEVANCE

Subsets of TILs, especially CD3⁺, CD8⁺ and FoxP3⁺ T cells are strongly associated with long-term oncological outcomes in patients with PDAC. To our knowledge, this is the first systematic review and meta-analysis on the prognostic value of TILs in pancreatic cancer.

Chemokines and their Receptors: Multifaceted Roles in Cancer Progression and Potential Value as Cancer Prognostic Markers

Chemokines are chemotactic cytokines that mediate immune cell chemotaxis and lymphoid tissue development. Recent advances have indicated that chemokines and their cognate receptors play critical roles in cancer-related inflammation and cancer progression. On the basis of these findings, the chemokine system has become a new potential drug target for cancer immunotherapy. In this review, we summarize the essential roles of the complex network of chemokines and their receptors in cancer progression. Furthermore, we discuss the potential value of the chemokine system as a cancer prognostic marker. The chemokine system regulates the infiltration of immune cells into the tumor microenvironment, which induces both pro- and anti-immunity and promotes or suppresses tumor growth and proliferation, angiogenesis, and metastasis. Increasing evidence indicates the promising prognostic value of the chemokine system in cancer patients. While CCL2, CXCL10, and CX3CL1/CX3CR1 can serve as favorable or unfavorable prognostic factors depending on the cancer types, CCL14 and XCL1 possess good prognostic value. Other chemokines such as CXCL1, CXCL8, and CXCL12 are poor prognostic markers. Despite vast advances in our understanding of the complex nature of the chemokine system in tumor biology, knowledge about the multifaceted roles of the chemokine system in different types of cancers is still limited. Further studies are necessary to decipher distinct roles within the chemokine system in terms of cancer progression and to validate their potential value in cancer prognosis.

Janus or Hydra: The Many Faces of T Helper Cells in the Human Tumour Microenvironment

CD4+ T helper (T_H) cells are key regulators in the tumour immune microenvironment (TIME), mediating the adaptive immunological response towards cancer, mainly through the activation of cytotoxic CD8+ T cells. After antigen recognition and proper co-stimulation, naïve T_H cells are activated, undergo clonal expansion, and release cytokines that will define the differentiation of a specific effector T_H cell subtype. These different subtypes have different functions, which can mediate both anti- and pro-tumour immunological responses. Here, we present the dual role of T_H cells restraining or promoting the tumour, the factors controlling their homing and differentiation in the TIME, their influence on immunotherapy, and their use as prognostic indicators.