Prognostic value of immune factors in the tumor microenvironment of patients with pancreatic ductal adenocarcinoma

Immunohistochemical Evaluation of the Tumor Immune Microenvironment in Pancreatic Ductal Adenocarcinoma

Background: Pancreatic ductal adenocarcinoma is an aggressive neoplasm with a complex carcinogenesis process that must be understood through the interactions between tumor cells and tumor microenvironment cells. Methods: This study was retrospective with a chronological extension period of 16 years and included 56 cases of pancreatic ductal adenocarcinoma. This study identified, quantified, and correlated the cells of the tumor immune microenvironment in pancreatic ductal adenocarcinoma with major prognostic factors as well as overall survival, using an extensive panel of immunohistochemical markers. Results: Three tumor immunotypes were identified: subtype A (hot immunotype), subtype B (intermediate immunotype), and subtype C (cold immunotype). Patients with immunotype C exhibit considerably higher rates of both pancreatic fistulas and acute pancreatitis. Immunotypes B and C significantly increased the risk of this complication by factors of 3.68 (p = 0.002) and 3.94 (p = 0.001), respectively. The estimated probabilities of fistula formation for each immunotype are as follows: 2.5% for immunotype A, 25% for immunotype B, and 28% for immunotype C. There was a statistically significant difference in median survival times according to tumor immunotype (p < 0.001). Specifically, patients with immunotype C tumors had a median survival time of only 120.5 days, compared to 553.5 days for those with immunotype A and 331.5 for immunotype B tumors. Conclusions: The identification of the immunotype of pancreatic ductal adenocarcinoma can be a predictive factor for the occurrence of complications such as pancreatic fistula as well as for overall survival.

Fluorouracil enhances the anti-pancreatic cancer effect of anti-PD-L1 antibodies via up-regulating the expression of PD-L1 in cancer cells

Pancreatic cancer is characterized by occult onset, low early diagnosis rate, rapid progress, and poor prognosis. Due to the low response rate and low programmed cell death ligand 1 (PD-L1) expression in pancreatic cancer, the therapeutic application of PL-L1 inhibitors in pancreatic cancer is greatly limited. In vitro studies showed that the expression of PD-L1 increased in pancreatic cancer cells stimulated by fluorouracil (5-FU). We aim to explore the combined effect of 5-FU and anti-PD-L1 antibodies and to provide a reference for the clinical application of PD-L1 antibodies in pancreatic cancer. In the current study, male BALB/c mice were adopted to construct a tumor-bearing model of pancreatic cancer cells. 5-FU and anti-mouse PD-L1 antibodies were combined and administered to evaluate their synergistic effects. The enhancing immune cytotoxicity effect of 5-FU sensitizing the anti-PD-L1 antibody in vivo and in vitro was analyzed by immunohistochemistry and western blot assays. Results showed that 5-FU and anti-PD-L1 antibody combination increased the expression of PD-L1 and IFN-γ, and infiltration of CD8+ T lymphocytes in pancreatic xenograft tumor tissues, which was proven by immunohistochemistry and western analysis. Moreover, the combination with the 5-FU remarkably enhanced the immune cytotoxicity of anti-PD-L1 antibodies in mice. In vitro analysis demonstrates that 5-FU increases the expression of PD-L1 on the surface of pancreatic cancer cell lines via up-regulating nuclear factor kappa B (NF-κB) and Protein kinase B (AKT) pathways. This synergistic effect could be abolished by NF-κB and AKT inhibitors.

Elevated SAMD3 expression in T cells predicts improved survival in pancreatic ductal adenocarcinoma patients

OBJECTIVE

Pancreatic ductal adenocarcinoma (PDAC) has an immune-suppressive tumor microenvironment that contributes to resistance to immunotherapy. This study aimed to demonstrate that elevated sterile alpha motif domain-containing protein 3 (SAMD3) expression in effector CD8+ T cells was associated with improved survival in PDAC patients.

DESIGN

We investigated the heterogeneity and gene expression profiles of T cells using a single-cell RNA sequencing (sc-RNA-seq) dataset comprised of human PDAC samples. SAMD3 mRNA expression was further evaluated in a tumor-specific OT-I/ovalbumin (OVA) mouse model. SAMD3 levels and their clinical significance were evaluated via immunohistochemistry (IHC) analysis.

RESULTS

SAMD3 was highly expressed in cytotoxic CD8+ T cells, with expression significantly downregulated during T cell exhaustion. SAMD3 levels were positively correlated with CD8+ T cell function. In PDAC patients, high SAMD3 levels in T cells were associated with improved overall survival (OS), disease-free survival (DFS), and T cell infiltration. A patient exhibiting partial response to combination immunotherapy also showed high SAMD3 levels in T cells.

CONCLUSION

SAMD3 is a biomarker of T cell function, with elevated expression in T cells predicting improved survival. These findings highlight the potential of precision immunotherapy approaches for treating PDAC.

Identification of cold tumor induction-related markers in pancreatic cancer and the clinical implication of PCDH7

PURPOSE

Pancreatic ductal adenocarcinoma (PDAC) is considered a "cold" tumor because the tumor immune microenvironment (TIME) exhibits poor intratumoral T-cell infiltration. This study aimed to identify the marker genes associated with induction of cold TIME in PDAC cells.

METHODS

We orthotopically transplanted 10 primary cultures of PDAC derived from KrasG12D/+; Trp53R172H/+; Pdx-1-Cre (KPC) mice into immunocompetent mice and evaluated TIME by immunohistochemistry (IHC) staining of CD8. We divided primary cultures into two groups: cold TIME group with low CD8+ T-cell infiltration and a hot TIME group with high infiltration. RNA sequencing was performed to identify specific genes in the cold TIME group, and single-cell RNA sequencing (scRNA-seq) data was used for validation. IHC was performed to evaluate expressions in human PDAC samples.

RESULTS

We identified six genes specific in PDAC cells to the cold TIME group by RNA sequencing; these were defined as "cold tumor induction-related genes". Human PDAC scRNA-seq data revealed that cold tumor induction-related genes were significantly and negatively correlated with the number of CD8+ T-cells (p = 0.0341). These genes included protocadherin 7 (PCDH7). High expression of PCDH7 significantly and negatively correlated with the number of CD8+ T-cells in scRNA-seq (p = 0.0474) and IHC (p = 0.0110) data using human PDAC samples. PCDH7 was an independent factor for poor prognosis in PDAC (overall survival: hazard ratio = 2.07, p = 0.0367).

CONCLUSION

PCDH7 is a prognostic marker associated with CD8+ T-cell infiltration for PDAC patients.

Challenges and Opportunities in Targeting the Complex Pancreatic Tumor Microenvironment

Pancreatic ductal adenocarcinoma (PDAC) is the third leading cause of cancer-related deaths with a 5-year survival rate of 13%. Surgical resection remains the only curative option as systemic therapies offer limited benefit. Poor response to chemotherapy and immunotherapy is due, in part, to the dense stroma and heterogeneous tumor microenvironment (TME). Opportunities to target the PDAC stroma may increase the effectiveness of existing or novel therapies. Current strategies targeting the stromal compartment within the PDAC TME primarily focus on degrading extracellular matrix or inhibiting stromal cell activity, angiogenesis, or hypoxic responses. In addition, extensive work has attempted to use immune targeting strategies to improve clinical outcomes. Preclinically, these strategies show promise, especially with the ability to alter the tumor ecosystem; however, when translated to the clinic, most of these trials have failed to improve overall patient outcomes. In this review, we catalog the heterogenous elements of the TME and discuss the potential of combination therapies that target the heterogeneity observed in the TME between patients and how molecular stratification could improve responses to targeted and combination therapies.

Dendritic cells pulsed with multifunctional Wilms' tumor 1 (WT1) peptides combined with multiagent chemotherapy modulate the tumor microenvironment and enable conversion surgery in pancreatic cancer

BACKGROUND

We aimed to develop a chemoimmunotherapy regimen consisting of a novel Wilms' tumor 1 (WT1) peptide-pulsed dendritic cell (WT1-DC) vaccine and multiagent chemotherapy and to investigate the safety, clinical outcomes, and WT1-specific immune responses of patients with unresectable advanced pancreatic ductal adenocarcinoma (UR-PDAC) who received this treatment.

METHODS

Patients with UR-PDAC with stage III disease (locally advanced (LA-PDAC; n=6)), stage IV disease (metastatic (M-PDAC; n=3)), or recurrent disease after surgery (n=1) were enrolled in this phase I study. The patients received one cycle of nab-paclitaxel plus gemcitabine alone followed by 15 doses of the WT1-DC vaccine independent of chemotherapy. The novel WT1 peptide cocktail was composed of a multifunctional helper peptide specific for major histocompatibility complex class II, human leukocyte antigen (HLA)-A*02:01, or HLA-A*02:06 and a killer peptide specific for HLA-A*24:02.

RESULTS

The chemoimmunotherapy regimen was well tolerated. In the nine patients for whom a prognostic analysis was feasible, the clinical outcomes of long-term WT1 peptide-specific delayed-type hypersensitivity (WT1-DTH)-positive patients (n=4) were significantly superior to those of short-term WT1-DTH-positive patients (n=5). During chemoimmunotherapy, eight patients were deemed eligible for conversion surgery and underwent R0 resection (four patients with LA-PDAC, one patient with M-PDAC, and one recurrence) or R1 resection (one patient with M-PDAC), and one patient with LA-PDAC was determined to be unresectable. Long-term WT1-DTH positivity was observed in three of the four patients with R0-resected LA-PDAC. These three patients exhibited notable infiltration of T cells and programmed cell death protein-1+ cells within the pancreatic tumor microenvironment (TME). All patients with long-term WT1-DTH positivity were alive for at least 4.5 years after starting therapy. In patients with long-term WT1-DTH positivity, the percentage of WT1-specific circulating CD4+ or CD8+ T cells that produced IFN-γ or TNF-α was significantly greater than that in patients with short-term WT1-DTH positivity after two vaccinations. Moreover, after 12 vaccinations, the percentages of both circulating regulatory T cells and myeloid-derived suppressor cells were significantly lower in patients with long-term WT1-DTH-positive PDAC than in short-term WT1-DTH-positive patients.

CONCLUSIONS

Potent activation of WT1-specific immune responses through a combination chemoimmunotherapy regimen including the WT1-DC vaccine in patients with UR-PDAC may modulate the TME and enable conversion surgery, resulting in clinical benefits (Online supplemental file 1).

TRIAL REGISTRATION NUMBER

jRCTc030190195.

Intra-tumoral administration of CHST15 siRNA remodels tumor microenvironment and augments tumor-infiltrating T cells in pancreatic cancer

The dense stroma is one cause of poor efficacy of T cell-mediated immunotherapy in pancreatic ductal adenocarcinoma (PDAC). Carbohydrate sulfotransferase 15 (CHST15) is a proteoglycan-synthetic enzyme responsible for remodeling tumor stroma. Intra-tumoral injection of CHST15 small interfering RNA (siRNA) has been shown to increase the tumor-infiltrating T cells (TILs) in patients with unresectable PDAC. However, the mechanism underlying the enhanced accumulation of TILs is not fully explored. Here, we demonstrate that intra-tumoral injection of CHST15 siRNA locally and remotely diminishes myeloid-derived suppressor cells (MDSCs) and enhances TILs in mice. CHST15 was expressed by tumor cells and MDSCs in both tumor and tumor-draining lymph nodes (TDLNs), and CHST15 siRNA repressed stromal density, neutrophil extracellular traps, and Ly6C/G+ MDSCs in vivo. Remarkably, tumor growth inhibition was only observed in the immunocompetent KPC model, which is associated with enhanced TILs. In vitro, CHST15 siRNA significantly downregulated the levels of CHST15 and indoleamine 2,3-dioxygenase mRNA in CD33+ MDSCs derived from human peripheral blood mononuclear cells. These results suggest a dual role for intra-tumorally injected CHST15 siRNA on modulating the tumor immune microenvironment for T cell entry and remotely diminishing CHST15+ MDSCs, decreasing T cell suppression and expanding T cells in the TDLN, ultimately leading to an enhanced accumulation of TILs.

Keratin 17 modulates the immune topography of pancreatic cancer

BACKGROUND

The immune microenvironment impacts tumor growth, invasion, metastasis, and patient survival and may provide opportunities for therapeutic intervention in pancreatic ductal adenocarcinoma (PDAC). Although never studied as a potential modulator of the immune response in most cancers, Keratin 17 (K17), a biomarker of the most aggressive (basal) molecular subtype of PDAC, is intimately involved in the histogenesis of the immune response in psoriasis, basal cell carcinoma, and cervical squamous cell carcinoma. Thus, we hypothesized that K17 expression could also impact the immune cell response in PDAC, and that uncovering this relationship could provide insight to guide the development of immunotherapeutic opportunities to extend patient survival.

METHODS

Multiplex immunohistochemistry (mIHC) and automated image analysis based on novel computational imaging technology were used to decipher the abundance and spatial distribution of T cells, macrophages, and tumor cells, relative to K17 expression in 235 PDACs.

RESULTS

K17 expression had profound effects on the exclusion of intratumoral CD8+ T cells and was also associated with decreased numbers of peritumoral CD8+ T cells, CD16+ macrophages, and CD163+ macrophages (p < 0.0001). The differences in the intratumor and peritumoral CD8+ T cell abundance were not impacted by neoadjuvant therapy, tumor stage, grade, lymph node status, histologic subtype, nor KRAS, p53, SMAD4, or CDKN2A mutations.

CONCLUSIONS

Thus, K17 expression correlates with major differences in the immune microenvironment that are independent of any tested clinicopathologic or tumor intrinsic variables, suggesting that targeting K17-mediated immune effects on the immune system could restore the innate immunologic response to PDAC and might provide novel opportunities to restore immunotherapeutic approaches for this most deadly form of cancer.

Intratumoral T-cell receptor repertoire composition predicts overall survival in patients with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy that is refractory to immune checkpoint inhibitor therapy. However, intratumoral T-cell infiltration correlates with improved overall survival (OS). Herein, we characterized the diversity and antigen specificity of the PDAC T-cell receptor (TCR) repertoire to identify novel immune-relevant biomarkers. Demographic, clinical, and TCR-beta sequencing data were collated from 353 patients across three cohorts that underwent surgical resection for PDAC. TCR diversity was calculated using Shannon Wiener index, Inverse Simpson index, and "True entropy." Patients were clustered by shared repertoire specificity. TCRs predictive of OS were identified and their associated transcriptional states were characterized by single-cell RNAseq. In multivariate Cox regression models controlling for relevant covariates, high intratumoral TCR diversity predicted OS across multiple cohorts. Conversely, in peripheral blood, high abundance of T-cells, but not high diversity, predicted OS. Clustering patients based on TCR specificity revealed a subset of TCRs that predicts OS. Interestingly, these TCR sequences were more likely to encode CD8+ effector memory and CD4+ T-regulatory (Tregs) T-cells, all with the capacity to recognize beta islet-derived autoantigens. As opposed to T-cell abundance, intratumoral TCR diversity was predictive of OS in multiple PDAC cohorts, and a subset of TCRs enriched in high-diversity patients independently correlated with OS. These findings emphasize the importance of evaluating peripheral and intratumoral TCR repertoires as distinct and relevant biomarkers in PDAC.

Keratin 17 modulates the immune topography of pancreatic cancer

Background

The immune microenvironment impacts tumor growth, invasion, metastasis, and patient survival and may provide opportunities for therapeutic intervention in pancreatic ductal adenocarcinoma (PDAC). Although never studied as a potential modulator of the immune response in most cancers, Keratin 17 (K17), a biomarker of the most aggressive (basal) molecular subtype of PDAC, is intimately involved in the histogenesis of the immune response in psoriasis, basal cell carcinoma, and cervical squamous cell carcinoma. Thus, we hypothesized that K17 expression could also impact the immune cell response in PDAC, and that uncovering this relationship could provide insight to guide the development of immunotherapeutic opportunities to extend patient survival.

Methods

Multiplex immunohistochemistry (mIHC) and automated image analysis based on novel computational imaging technology were used to decipher the abundance and spatial distribution of T cells, macrophages, and tumor cells, relative to K17 expression in 235 PDACs.

Results

K17 expression had profound effects on the exclusion of intratumoral CD8 + T cells and was also associated with decreased numbers of peritumoral CD8 + T cells, CD16 + macrophages, and CD163 + macrophages (p < 0.0001). The differences in the intratumor and peritumoral CD8 + T cell abundance were not impacted by neoadjuvant therapy, tumor stage, grade, lymph node status, histologic subtype, nor KRAS, p53, SMAD4, or CDKN2A mutations.

Conclusions

Thus, K17 expression correlates with major differences in the immune microenvironment that are independent of any tested clinicopathologic or tumor intrinsic variables, suggesting that targeting K17-mediated immune effects on the immune system could restore the innate immunologic response to PDAC and might provide novel opportunities to restore immunotherapeutic approaches for this most deadly form of cancer.

Infiltration of CD3+ and CD8+ lymphocytes in association with inflammation and survival in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinomas (PDAC) have heterogeneous tumor microenvironments relatively devoid of infiltrating immune cells. We aimed to quantitatively assess infiltrating CD3+ and CD8+ lymphocytes in a treatment-naïve patient cohort and assess associations with overall survival and microenvironment inflammatory proteins.

METHODS

Tissue microarrays were immunohistochemically stained for CD3+ and CD8+ lymphocytes and quantitatively assessed using QuPath. Levels of inflammation-associated proteins were quantified by multiplexed, enzyme-linked immunosorbent assay panels on matching tumor and tissue samples.

RESULTS

Our findings revealed a significant increase in both CD3+ and CD8+ lymphocytes populations in PDAC compared with non-PDAC tissue, except when comparing CD8+ percentages in PDAC versus intraductal papillary mucinous neoplasms (IPMN) (p = 0.5012). Patients with quantitatively assessed CD3+ low tumors (lower 50%) had shorter survival (median 273 days) compared to CD3+ high tumors (upper 50%) with a median overall survival of 642.5 days (p = 0.2184). Patients with quantitatively assessed CD8+ low tumors had significantly shorter survival (median 240 days) compared to CD8+ high tumors with a median overall survival of 1059 days (p = 0.0003). Of 41 proteins assessed in the inflammation assay, higher levels of IL-1B and IL-2 were significantly associated with decreased CD3+ infiltration (r = -0.3704, p = 0.0187, and r = -0.4275, p = 0.0074, respectively). Higher levels of IL-1B were also significantly associated with decreased CD8+ infiltration (r = -0.4299, p = 0.0045), but not IL-2 (r = -0.0078, p = 0.9616). Principal component analysis of the inflammatory analytes showed diverse inflammatory responses in PDAC.

CONCLUSION

In this work, we found a marked heterogeneity in infiltrating CD3+ and CD8+ lymphocytes and individual inflammatory responses in PDAC. Future mechanistic studies should explore personalized therapeutic strategies to target the immune and inflammatory components of the tumor microenvironment.

CD3-CD8 immune score associated with a clinical score stratifies PDAC prognosis regardless of adjuvant or neoadjuvant chemotherapy

Stratification of the prognosis of pancreatic cancer (PDAC) patients treated by surgery is based solely on clinical variables, such as tumor stage and node status. The development of biomarkers of relapse is needed, especially to drive administration of adjuvant therapy in this at-risk population. Our study evaluates the prognostic performance of a CD3- and CD8-based immune score. CD3, CD8 and Foxp3 expression were evaluated on whole slides in two retrospective PDAC cohorts totaling 334 patients. For this study, we developed an immune score to estimate CD3 and CD8 infiltration in both tumor core and invasive margin using computer-guided analysis with QuPath software. Variables were combined in a dichotomous immune score. The association between immune and clinical scores, and both PFS and OS was investigated. We observed that a dichotomous immune score predicts both PFS and OS of localized PDAC. By univariate and multivariate analysis, immune score, tumor grade, adjuvant therapy, lymph node status, and adjuvant chemotherapy administration were associated with PFS and OS. We subsequently associated the PDAC immune score and clinical variables in a combined score. This combined score predicted patient outcomes independently of adjuvant or neoadjuvant treatment, and improved patient prognostic prediction compared to clinical variables or immune score alone.

Spatial immune composition of tumor microenvironment in patients with pancreatic cancer

This study examined the composition of the immune microenvironment at different sites within resected pancreas specimens from patients with pancreatic ductal adenocarcinoma (PDAC). Therefore, single-cell suspensions were made from fresh tumor and non-tumorous tissue. Fourteen patients were included from whom twelve PDAC and five non-tumorous samples were obtained. These samples were analyzed with a nineteen marker panel on the Aurora spectral flow cytometer. Furthermore, slides from formalin-fixed paraffine PDACs of eight additional patients were stained with eight markers and analyzed by multispectral imaging. These corresponded to central tumor, periphery of the tumor, i.e., invasive front and resected lymph node and were divided into tumor and adjacent tissue. In the single-cell suspension, a decreased ratio between lymphoid and myeloid cells and between M1 and M2 macrophages was observed in the tumor tissue compared to non-tumorous tissue. Furthermore, an increase in CD169 + macrophages in patients undergoing neoadjuvant therapy was found. Using immunofluorescence, more macrophages compared to T cells were observed, as well as a lower ratio of CD8 to M2 macrophage, a higher ratio of CD4-CD8 T cells and a higher ratio of immune-suppressive cells to pro-inflammatory cells in the PDAC area compared to the adjacent non-tumorous tissue. Finally, there were more immune-suppressive cells in the central tumor area compared to the invasive front. In conclusion, we show a gradient in the immune-suppressive environment in PDAC from most suppressive in the central tumor to least suppressive in distant non-tumorous tissue.

Unraveling the impact of sialic acids on the immune landscape and immunotherapy efficacy in pancreatic cancer

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers. Despite the successful application of immune checkpoint blockade in a range of human cancers, immunotherapy in PDAC remains unsuccessful. PDAC is characterized by a desmoplastic, hypoxic and highly immunosuppressive tumor microenvironment (TME), where T-cell infiltration is often lacking (immune desert), or where T cells are located distant from the tumor islands (immune excluded). Converting the TME to an immune-inflamed state, allowing T-cell infiltration, could increase the success of immunotherapy in PDAC.

METHOD

In this study, we use the KPC3 subcutaneous PDAC mouse model to investigate the role of tumor-derived sialic acids in shaping the tumor immune landscape. A sialic acid deficient KPC3 line was generated by genetic knock-out of the CMAS (cytidine monophosphate N-acetylneuraminic acid synthetase) enzyme, a critical enzyme in the synthesis of sialic acid-containing glycans. The effect of sialic acid-deficiency on immunotherapy efficacy was assessed by treatment with anti-programmed cell death protein 1 (PD-1) and agonistic CD40.

RESULT

The absence of sialic acids in KPC3 tumors resulted in increased numbers of CD4+ and CD8+ T cells in the TME, and reduced frequencies of CD4+ regulatory T cells (Tregs) within the T-cell population. Importantly, CD8+ T cells were able to infiltrate the tumor islands in sialic acid-deficient tumors. These favorable alterations in the immune landscape sensitized sialic acid-deficient tumors to immunotherapy, which was ineffective in sialic acid-expressing KPC3 tumors. In addition, high expression of sialylation-related genes in human pancreatic cancer correlated with decreased CD8+ T-cell infiltration, increased presence of Tregs, and poorer survival probability.

CONCLUSION

Our results demonstrate that tumor-derived sialic acids mediate T-cell exclusion within the PDAC TME, thereby impairing immunotherapy efficacy. Targeting sialic acids represents a potential strategy to enhance T-cell infiltration and improve immunotherapy outcomes in PDAC.

Clinical significance of programmed cell death-ligand expression in small bowel adenocarcinoma is determined by the tumor microenvironment

BACKGROUND

Comprehensive genomic analysis has shown that small bowel adenocarcinoma (SBA) has different genomic profiles from gastric and colorectal cancers. Hence, it is essential to establish chemotherapeutic regimens based on SBA characteristics. The expression of programmed cell death-ligand 1 (PD-L1) and programmed cell death-ligand 2 (PD-L2) in SBA is not fully understood. Anti-PD-L1/PD-1 therapy uses tumor-infiltrating lymphocytes (TILs); therefore, the status of TILs in the tumor microenvironment (TME) may influence their efficacy. The ratio of FoxP3+ to CD8+ T cells has been reported to be useful in predicting the prognosis of digestive system cancers.

AIM

To investigate the clinicopathological significance of PD-L1/2 expression according to the status of TILs in SBA tissues.

METHODS

We performed immunohistochemical analysis for PD-L1, PD-L2, CD8, FoxP3, and DNA mismatch repair (MMR) proteins using formalin-fixed, paraffin-embedded tissues from 50 patients diagnosed with primary SBA. The immunoreactivities of PD-L1 and PD-L2 were determined separately in tumor cells and tumor-infiltrating immune cells throughout the tumor center and invasive margins, and finally evaluated using the combined positive score (CPS). We assessed CD8+ and FoxP3+ T cells in the intratumoral and tumor-surrounding stroma. Subsequently, we calculated and summed the ratio of FoxP3 to CD8+ T cell counts. Immune-related cell densities were graded as low or high. Immunohistochemical results were compared with clinicopathological factors and patient prognosis. The distribution of cancer-specific survival (CSS) was estimated using the Kaplan-Meier method, and the log-rank test was used to test for significant differences in CSS. A Cox proportional hazard model was also used to assess the effect of tumor variables on CSS.

RESULTS

PD-L1 expression was positive in 34% in tumor cells (T-PD-L1) and 54% in tumor-infiltrating immune cells (I-PD-L1) of the cases examined. T-PD-L2 was positive in 34% and I-PD-L2 was positive in 42% of the cases. PD-L1 CPS ≥ 10 and PD-L2 CPS ≥ 10 were observed in 50% and 56% of the cases, respectively. Deficient MMR (dMMR) was 14% of the cases. T-PD-L1, I-PD-L1 and PD-L1 CPS ≥ 10 were all significantly associated with dMMR (P = 0.037, P = 0.009, and P = 0.005, respectively). T-PD-L1, I-PD-L1, and PD-L1 CPS ≥ 10 were all associated with deeper depth of invasion (P = 0.001, P = 0.024, and P = 0.002, respectively). I-PD-L2 expression and PD-L2 CPS ≥ 10 were significantly higher in the differentiated histological type (P = 0.015 and P = 0.030, respectively). The I-PD-L1 and I-PD-L2 levels were significantly associated with better CSS (P = 0.037 and P = 0.015, respectively). CD8-high was significantly associated with less lymph node metastasis (P = 0.047), less distant metastasis (P = 0.024), less peritoneal dissemination (P = 0.034), and earlier TNM stage (P = 0.047). The CD8-high group had better prognosis than the CD8-low group (P = 0.018). FoxP3 expression was not associated with any clinicopathological factors or prognosis. We found that patients with PD-L2 CPS ≥ 10 tended to have worse prognosis in the FoxP3/CD8-low group (P = 0.088).

CONCLUSION

The clinicopathological significance of PD-L1/2 expression may differ depending on the TME status. Immune checkpoint inhibitors may improve the prognosis of SBA patients with low FoxP3/CD8 ratio and PD-L2 expression.

Silencing of tumoral carbohydrate sulfotransferase 15 reactivates lymph node pancreatic cancer T cells in mice

Limited intratumoral T-cell infiltration in pancreatic ductal adenocarcinoma (PDAC) is an obstacle to immunotherapy, yet the efficient approach to enhance tumor-infiltrating T cells is not fully established. Here, we show that tumor-specific knockdown of carbohydrate sulfotransferase 15 (CHST15), a tumor stromal proteoglycan-synthetic enzyme, suppresses tumor growth in a T-cell-dependent manner in a murine model of PDAC. Silencing of tumoral CHST15 unexpectedly expanded CD4+ and CD8+ T cells in tumor draining LN (TDLN), leading to accelerated accumulation of EdU+ proliferating CD4+ and CD8+ T cells and granzyme B+ CD8+ T cells in the tumor. RNA expression analysis indicated that tumoral CHST15 knockdown (KD) downregulated matrix remodeling-related genes, while upregulated anti-tumor T-cell activity-related genes in both tumor and TDLN. CHST15 KD significantly diminished intratumoral and TDLN Ly6C/G+ myeloid-derived suppressor cells prior to TDLN T-cell expansion, suggesting that tumoral CHST15 remotely regulated myeloid-derived suppressor cell mediated T-cell suppression in the TDLN. Our findings illustrate a novel immunotherapeutic potential of tumoral CHST15 blockage by reactivating T cells in immune suppressive TDLN of PDAC.

Interferon-expressing oncolytic adenovirus + chemoradiation inhibited pancreatic cancer growth in a hamster model

Past clinical trials of adjuvant therapy combined with interferon (IFN) alpha, fluorouracil, cisplatin, and radiation improved the 5-year survival rate of pancreatic ductal adenocarcinoma (PDAC). However, these trials also revealed the disadvantages of the systemic toxicity of IFN and insufficient delivery of IFN. To improve efficacy and tolerability, we have developed an oncolytic adenovirus-expressing IFN (IFN-OAd). Here, we evaluated IFN-OAd in combination with chemotherapy (gemcitabine + nab-paclitaxel) + radiation. Combination index (CI) analysis showed that IFN-OAd + chemotherapy + radiation was synergistic (CI <1). Notably, IFN-OAd + chemotherapy + radiation remarkably suppressed tumor growth and induced a higher number of tumor-infiltrating lymphocytes without severe side toxic effects in an immunocompetent and adenovirus replication-permissive hamster PDAC model. This is the first study to report that gemcitabine + nab-paclitaxel, the current first-line chemotherapy for PDAC, did not hamper virus replication in a replication-permissive immunocompetent model. IFN-OAd has the potential to overcome the barriers to clinical application of IFN-based therapy through its tumor-specific expression of IFN, induction of antitumor immunity, and sensitization with chemoradiation. Combining IFN-OAd with gemcitabine + nab-paclitaxel + radiation might be an effective and clinically beneficial treatment for PDAC patients.

Tumor-specific CD4 T cells instruct monocyte fate in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDA) orchestrates a suppressive tumor microenvironment that fosters immunotherapy resistance. Tumor-associated macrophages (TAMs) are the principal immune cell infiltrating PDA and are heterogeneous. Here, by employing macrophage fate-mapping approaches and single-cell RNA sequencing, we show that monocytes give rise to most macrophage subsets in PDA. Tumor-specific CD4, but not CD8, T cells promote monocyte differentiation into MHCIIhi anti-tumor macrophages. By conditional major histocompatibility complex (MHC) class II deletion on monocyte-derived macrophages, we show that tumor antigen presentation is required for instructing monocyte differentiation into anti-tumor macrophages, promoting Th1 cells, abrogating Treg cells, and mitigating CD8 T cell exhaustion. Non-redundant IFNγ and CD40 promote MHCIIhi anti-tumor macrophages. Intratumoral monocytes adopt a pro-tumor fate indistinguishable from that of tissue-resident macrophages following loss of macrophage MHC class II or tumor-specific CD4 T cells. Thus, tumor antigen presentation by macrophages to CD4 T cells dictates TAM fate and is a major determinant of macrophage heterogeneity in cancer.

Expression and role of the immune checkpoint regulator PD-L1 in the tumor-stroma interplay of pancreatic ductal adenocarcinoma

Introduction

Immune checkpoint inhibitors (ICI), e.g., targeting programmed cell death protein 1-ligand 1 (PD-L1) or its receptor PD-1, have markedly improved the therapy of many cancers but so far failed in pancreatic ductal adenocarcinoma (PDAC). Macrophages represent one of the most abundant immune cell populations within the tumor microenvironment (TME) of PDAC being able to either support or restrain tumor progression depending on their phenotype. To better understand treatment failure of PD-L1/PD-1 inhibitors in PDAC, this study examined PD-L1 expression in the context of a dynamic TME in PDAC with a particular focus on the impact of macrophages.

Methods

Formalin-fixed and paraffin embedded tissue samples of primary PDAC tissues and corresponding liver metastases were used for immunohistochemical analyses. Serial sections were stained with antibodies detecting Pan-Cytokeratin, CD68, CD163, CD8, and PD-L1.To investigate whether the PD-1/PD-L1 axis and macrophages contribute to immune escape of PDAC cells, a stroma enriched 3D spheroid coculture model was established in vitro, using different PDAC cell lines and macrophages subtypes as well as CD8+ T cells. Functional and flow cytometry analyses were conducted to characterize cell populations.

Results

Immunohistochemical analyses revealed that PD-L1 is mainly expressed by stroma cells, including macrophages and not PDAC cells in primary PDAC tissues and corresponding liver metastases. Notably, high local abundance of macrophages and strong PD-L1 staining were commonly found at invasion fronts of tumoral lesions between CD8+ T cells and tumor cells. In order to investigate whether PD-L1 expressing macrophages impact the response of PDAC cells to treatment with PD-L1/PD-1 inhibitors, we developed a spheroid model comprising two different PDAC cell lines and different ratios of in vitro differentiated primary M1- or M2-like polarized macrophages. In line with our in situ findings, high PD-L1 expression was observed in macrophages rather than PDAC cells, which was further increased by the presence of PDAC cells. The effector phenotype of co-cultured CD8+ T cells exemplified by expression of activation markers and release of effector molecules was rather enhanced by PDAC macrophage spheroids, particularly with M1-like macrophages compared to mono-culture spheroids. However, this was not associated with enhanced PDAC cell death. ICI treatment with either Durvalumab or Pembrolizumab alone or in combination with Gemcitabine hardly affected the effector phenotype of CD8+ T cells along with PDAC cell death. Thus, despite strong PD-L1 expression in macrophages, ICI treatment did not result in an enhanced activation and cytotoxic phenotype of CD8+ T cells.

Conclusion

Overall, our study revealed novel insights into the interplay of PDAC cells and macrophages in the presence of ICI.

Identification of a novel immune checkpoint molecule V-set immunoglobulin domain-containing 4 that leads to impaired immunity infiltration in pancreatic ductal adenocarcinoma

BACKGROUND

Checkpoint-based immunotherapy has failed to elicit responses in the majority of patients with pancreatic cancer. In our study, we aimed to identify the role of a novel immune checkpoint molecule V-set Ig domain-containing 4 (VSIG4) in pancreatic ductal adenocarcinoma (PDAC).

METHODS

Online datasets and tissue microarray (TMA) were utilized to analyze the expression level of VSIG4 and its correlation with clinical parameters in PDAC. CCK8, transwell assay and wound healing assay were applied to explore the function of VSIG4 in vitro. Subcutaneous, orthotopic xenograft and liver metastasis model was established to explore the function of VSIG4 in vivo. TMA analysis and chemotaxis assay were conducted to uncover the effect of VSIG4 on immune infiltration. Histone acetyltransferase (HAT) inhibitors and si-RNA were applied to investigate factors that regulate the expression of VSIG4.

RESULTS

Both mRNA and protein levels of VSIG4 were higher in PDAC than normal pancreas in TCGA, GEO, HPA datasets and our TMA. VSIG4 showed positive correlations with tumor size, T classification and liver metastasis. Patients with higher VSIG4 expression were related to poorer prognosis. VSIG4 knockdown impaired the proliferation and migration ability of pancreatic cancer cells both in vitro and in vivo. Bioinformatics study showed positive correlation between VSIG4 and infiltration of neutrophil and tumor-associated macrophages (TAMs) in PDAC, and it inhibited the secretion of cytokines. According to our TMA panel, high expression of VSIG4 was correlated with fewer infiltration of CD8⁺ T cells. Chemotaxis assay also showed knockdown of VSIG4 increased the recruitment of total T cells and CD8⁺ T cells. HAT inhibitors and knockdown of STAT1 led to decreased expression of VSIG4.

CONCLUSIONS

Our data indicate that VSIG4 contributes to cell proliferation, migration and resistance to immune attack, thus identified as a promising target for PDAC treatment with good prognostic value.

STNM01, the RNA oligonucleotide targeting carbohydrate sulfotransferase 15, as second-line therapy for chemotherapy-refractory patients with unresectable pancreatic cancer: An open label, phase I/IIa trial

BACKGROUND

The impact of stroma-targeting therapy on tumor immune suppression is largely unexplored. An RNA oligonucleotide, STNM01, has been shown to repress carbohydrate sulfotransferase 15 (CHST15) responsible for tumor proteoglycan synthesis and matrix remodeling. This phase I/IIa study aimed to evaluate the safety and efficacy of STNM01 in patients with unresectable pancreatic ductal adenocarcinoma (PDAC).

METHODS

This was an open-label, dose-escalation study of STNM01 as second-line therapy in gemcitabine plus nab-paclitaxel-refractory PDAC. A cycle comprised three 2-weekly endoscopic ultrasound-guided locoregional injections of STNM01 at doses of 250, 1,000, 2,500, or 10,000 nM in combination with S-1 (80-120 mg twice a day for 14 days every 3 weeks). The primary outcome was the incidence of dose-liming toxicity (DLT). The secondary outcomes included overall survival (OS), tumor response, changes in tumor microenvironment on immunohistopathology, and safety (jRCT2031190055).

FINDINGS

A total of 22 patients were enrolled, and 3 cycles were repeated at maximum; no DLT was observed. The median OS was 7.8 months. The disease control rate was 77.3%; 1 patient showed complete disappearance of visible lesions in the pancreas and tumor-draining lymph nodes. Higher tumoral CHST15 expression was associated with poor CD3⁺ and CD8⁺ T cell infiltration at baseline. STNM01 led to a significant reduction in CHST15, and increased tumor-infiltrating CD3⁺ and CD8⁺ T cells in combination with S-1 at the end of cycle 1. Higher fold increase in CD3⁺ T cells correlated with longer OS. There were 8 grade 3 adverse events.

INTERPRETATION

Locoregional injection of STNM01 was well tolerated in patients with unresectable PDAC as combined second-line therapy. It prolonged survival by enhancing T cell infiltration in tumor microenvironment.

FUNDING

The present study was supported by the Japan Agency for Medical Research and Development (AMED).

C-reactive protein/albumin ratio and Glasgow prognostic score are associated with prognosis and infiltration of Foxp3+ or CD3+ lymphocytes in colorectal liver metastasis

BACKGROUND

Inflammatory indices and tumor-infiltrating lymphocytes (TILs) have prognostic value in many cancer types. This study aimed to assess the prognostic value of inflammatory indices and evaluate their correlation with survival and presence of TILs in patients with colorectal liver metastasis (CRLM).

METHODS

Medical records of 117 patients who underwent hepatectomy for CRLM were retrospectively reviewed. We calculated inflammatory indices comprising the neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, C-reactive protein/albumin ratio (CAR), and Glasgow prognostic score (GPS). Furthermore, we evaluated the relationship between these ratios and the GPS and survival rates and immunohistochemical results of tumor-infiltrating CD3+, CD8+, and Foxp3+ lymphocytes.

RESULTS

The patients with low CAR values and low GPS had significantly better overall survival as per the log-rank test (p = 0.025 and p = 0.012, respectively). According to the multivariate analysis using the Cox proportional hazard model, the CAR (hazard ratio [HR], 0.57; 95% confidence interval [CI], 0.33-0.99; p = 0.048) and GPS (HR, 0.40; 95% CI, 0.19-0.83; p = 0.013) were independent prognostic factors. Additionally, Foxp3+ lymphocytes were more common in samples from the patients with a low CAR (p = 0.041). Moreover, the number of CD3+ TILs was significantly higher in the patients with a low GPS (p = 0.015).

CONCLUSIONS

The CAR and GPS are simple, inexpensive, and objective markers associated with predicting survival in patients with CRLM. Moreover, they can predict the presence of Foxp3+ and CD3+ lymphocytes in the invasive margin of a tumor.

TRIAL REGISTRATION

Retrospectively registered. https://www.kurume-u.ac.jp/uploaded/attachment/14282.pdf .

Histone Deacetylase Inhibitors Restore Cancer Cell Sensitivity towards T Lymphocytes Mediated Cytotoxicity in Pancreatic Cancer

Despite medical advancements, the prognosis of pancreatic ductal adenocarcinoma (PDAC) has not improved significantly over the past 50 years. By utilising the large-scale genomic datasets available from the Australia Pancreatic Cancer Project (PACA-AU) and The Cancer Genomic Atlas Project (TCGA-PAAD), we studied the immunophenotype of PDAC in silico and identified that tumours with high cytotoxic T lymphocytes (CTL) killing activity were associated with favourable clinical outcomes. Using the STRING protein-protein interaction network analysis, the identified differentially expressed genes with low CTL killing activity were associated with TWIST/IL-6R, HDAC5, and EOMES signalling. Following Connectivity Map analysis, we identified 44 small molecules that could restore CTL sensitivity in the PDAC cells. Further high-throughput chemical library screening identified 133 inhibitors that effectively target both parental and CTL-resistant PDAC cells in vitro. Since CTL-resistant PDAC had a higher expression of histone proteins and its acetylated proteins compared to its parental cells, we further investigated the impact of histone deacetylase inhibitors (HDACi) on CTL-mediated cytotoxicity in PDAC cells in vitro, namely SW1990 and BxPC3. Further analyses revealed that givinostat and dacinostat were the two most potent HDAC inhibitors that restored CTL sensitivity in SW1990 and BxPC3 CTL-resistant cells. Through our in silico and in vitro studies, we demonstrate the novel role of HDAC inhibition in restoring CTL resistance and that combinations of HDACi with CTL may represent a promising therapeutic strategy, warranting its further detailed molecular mechanistic studies and animal studies before embarking on the clinical evaluation of these novel combined PDAC treatments.

Clinical Significance of Tumor-Infiltrating Conventional and Plasmacytoid Dendritic Cells in Pancreatic Ductal Adenocarcinoma

Simple Summary

The tumor immune contexture plays a pivotal role for the clinical outcome of cancer patients and the efficacy of various treatment modalities. Dendritic cells (DCs) represent a major component of the tumor immune architecture that can either efficiently promote antitumor immunity or contribute to immunosuppression. Here, we investigated the frequency, spatial organization, and clinical significance of tumor-infiltrating conventional DCs type 1 (cDC1s) and type 2 (cDC2s) and plasmacytoid DCs (pDCs) in pancreatic ductal adenocarcinoma (PDAC). A higher frequency of whole tumor area (WTA)- and tumor stroma (TS)-infiltrating cDC1s, and of intraepithelial tumor-infiltrating cDC2s, was significantly associated with improved survival. Furthermore, a higher density of both WTA- and TS-infiltrating cDC1s and pDCs emerged as an independent prognostic factor for better survival. These results provide evidence that tumor-infiltrating DCs are associated with survival of PDAC patients and may support the design of novel DC-based immunotherapeutic strategies.

Abstract

Dendritic cells (DCs) play a key role in the orchestration of antitumor immunity. Activated DCs efficiently enhance antitumor effects mediated by natural killer cells and T lymphocytes. Conversely, tolerogenic DCs essentially contribute to an immunosuppressive tumor microenvironment. Thus, DCs can profoundly influence tumor progression and clinical outcome of tumor patients. To gain novel insights into the role of human DCs in pancreatic ductal adenocarcinoma (PDAC), we explored the frequency, spatial organization, and clinical significance of conventional DCs type 1 (cDC1s) and type 2 (cDC2s) and plasmacytoid DCs (pDCs) in primary PDAC tissues. A higher density of whole tumor area (WTA)- and tumor stroma (TS)-infiltrating cDC1s was significantly associated with better disease-free survival (DFS). In addition, an increased frequency of intraepithelial tumor-infiltrating cDC2s was linked to better DFS and overall survival (OS). Furthermore, an increased density of WTA- and TS-infiltrating pDCs tended to improve DFS. Moreover, a higher frequency of WTA- and TS-infiltrating cDC1s and pDCs emerged as an independent prognostic factor for better DFS and OS. These findings indicate that tumor-infiltrating DCs can significantly influence the clinical outcome of PDAC patients and may contribute to the design of novel treatment options that target PDAC-infiltrating DCs.

Identification of solute carrier family genes related to the prognosis and tumor-infiltrating immune cells of pancreatic ductal adenocarcinoma

Background

Pancreatic ductal adenocarcinoma (PDAC) has persisted as one of the worst prognostic tumors with a 5-year survival rate of lower than 6%. Although many studies have investigated PDAC, new biomarkers are required to ensure early diagnosis and predict the prognosis of PDAC.

Methods

In this study, we used bioinformatics methods to evaluate differences in the expression of solute carrier (SLC) family genes in tumors and non-tumors. A Kaplan-Meier analysis, least absolute shrinkage and selection operator (LASSO) analysis, and multivariate Cox proportional hazards regression analysis were used to evaluate the relationship between SLC genes and prognosis using The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) datasets. The prognostic signature was constructed depending on the risk score to assess the impact of multiple genes on the prognosis, receiver operating characteristic (ROC) curves and forest plot was constructed to assess the ability to predict the prognosis and effects of clinical variables in both high- and low-risk groups. Tumor-infiltrating immune cells were evaluated using Cell-type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT) in both high- and low-risk groups.

Results

In 32 SLC genes, 9 were significantly associated with the OS after LASSO analysis. SLC19A3 (P=0.007), SLC25A39 (P=0.027), SLC39A11 (P=0.043) were significantly associated with prognosis and included into the prognostic model. CIBERSORT demonstrated that memory B cells (P=0.004), naive B cells (P=0.007), CD8 T cells (P=0.003), activated memory CD4 T cells (P=0.004), and activated NK cells (P=0.019) were significantly higher in the low-risk group. Gene set enrichment analysis (GSEA) showed that potential molecular mechanisms enriched in MYC and p53 signaling pathways.

Conclusions

SLC19A3, SLC25A35, and SLC39A11 were significantly relative to the prognosis of PDAC and changed the tumor microenvironment, as well as the MYC and p53 signaling pathways. The SLC19A3 gene may represent a new tumor suppressor in PDAC.