Neoadjuvant chemotherapy endows CD9 with prognostic value that differs between tumor and stromal areas in patients with pancreatic cancer.

BACKGROUND: The selective pressure imposed by chemotherapy creates a barrier to tumor eradication and an opportunity for metastasis and recurrence. As a newly discovered stemness marker of pancreatic ductal adenocarcinoma (PDAC), the impact of CD9 on tumor progression and patient's prognosis remain controversial. METHODS: A total of 179 and 211 PDAC patients who underwent surgical resection with or without neoadjuvant chemotherapy, respectively, were recruited for immunohistochemical analyses of CD9 expression in both tumor and stromal areas prior to statistical analyses to determine the prognostic impact and predictive accuracy of CD9. RESULTS: The relationship between CD9 and prognostic indicators was not significant in the non-neoadjuvant group. Nevertheless, CD9 expression in both tumor (T-CD9) and stromal areas (S-CD9) was significantly correlated with the clinicopathological features in the neoadjuvant group. High levels of T-CD9 were significantly associated with worse OS (p = 0.005) and RFS (p = 0.007), while positive S-CD9 showed the opposite results (OS: p = 0.024; RFS: p = 0.008). Cox regression analyses identified CD9 in both areas as an independent prognostic factor. The T&S-CD9 risk-level system was used to stratify patients with different survival levels. The combination of T&S-CD9 risk level and TNM stage were accurate predictors of OS (C-index: 0.676; AIC: 512.51) and RFS (C-index: 0.680; AIC: 519.53). The calibration curve of the nomogram composed of the combined parameters showed excellent predictive consistency for 1-year RFS. These results were verified using a validation cohort. CONCLUSION: Neoadjuvant chemotherapy endows CD9 with a significant prognostic value that differs between tumor and stromal areas in patients with pancreatic cancer.

Human splenic TER cells: A relevant prognostic factor acting via the artemin-GFRα3-ERK pathway in pancreatic ductal adenocarcinoma.

Splenectomy is routinely performed during distal or total pancreatectomy (DP or TP) for pancreatic ductal adenocarcinoma (PDAC), but information about its oncological value is limited. TER cells, nonimmune cells discovered in the spleens of tumour-bearing mice, are elicited by tumours and promote tumour progression, while their role in the clinical outcomes of patients with PDAC remains unclear. In our study, postoperative specimens from 622 patients who underwent DP or TP with splenectomy were analysed by flow cytometry or immunofluorescence, and the relationship between splenic TER cell count and clinical parameters was calculated. We also purified human TER cells for functional experiments and mechanistic studies. We found that TER cell numbers were increased only in the spleens of patients with PDAC but not in PDAC tissue and adjacent pancreatic tissue. High splenic TER cell counts independently predicted poor prognosis (P < .001) and indicated large tumour size, lymph node metastasis, advanced 8th AJCC/mAJCC stage and high CA19-9 classification (all P < .050) in patients with PDAC. Mechanistic analysis showed that TER cells express artemin, which facilitates the proliferation and invasion of PDAC cells by activating GFRα3-ERK signalling. Our study reveals that TER cell count is an indicator of poor prognosis of PDAC, while splenectomy during pancreatic surgery might provide oncological benefits in addition to ensuring the radical resection of PDAC.

Angiogenesis in pancreatic cancer: current research status and clinical implications.

Pancreatic cancer is one of the most lethal malignancies worldwide. Although the standard of care in pancreatic cancer has improved, prognoses for patients remain poor with a 5-year survival rate of < 5%. Angiogenesis, namely, the formation of new blood vessels from pre-existing vessels, is an important event in tumor growth and hematogenous metastasis. It is a dynamic and complex process involving multiple mechanisms and is regulated by various molecules. Inhibition of angiogenesis has been an established therapeutic strategy for many solid tumors. However, clinical outcomes are far from satisfying for pancreatic cancer patients receiving anti-angiogenic therapies. In this review, we summarize the current status of angiogenesis in pancreatic cancer research and explore the reasons for the poor efficacy of anti-angiogenic therapies, aiming to identify some potential therapeutic targets that may enhance the effectiveness of anti-angiogenic treatments.

Tumor-Infiltrating NETs Predict Postsurgical Survival in Patients with Pancreatic Ductal Adenocarcinoma.

BACKGROUND: Tumor-infiltrating neutrophils (TINs) indicate poor prognosis for patients with pancreatic ductal adenocarcinoma (PDAC). Activated neutrophils can generate neutrophil extracellular traps (NETs). Little is known about the presence and prognostic significance of tumor-infiltrating NETs in PDAC. METHODS: This study enrolled 317 patients, in two independent sets (training and validation), who underwent curative pancreatectomy for PDAC in Shanghai Cancer Center. TINs and NETs were identified by immunohistochemical staining for CD15 and citrullinated histone H3, respectively. The relationship between clinicopathological features and outcomes was analyzed. Accuracy of prognostic prediction models was evaluated using concordance index (C-index) and Akaike information criterion (AIC). RESULTS: NETs were associated with OS (both, P < 0.001) and RFS (both, P < 0.001) in the training and validation sets. Tumor-infiltrating NETs predicted poor postsurgical survival of patients with PDAC. Moreover, multivariate analysis identified NETs and AJCC TNM stage as two independent prognostic factors for OS and RFS. Combination of NETs with the 8th edition TNM staging system (C-index, 0.6994 and 0.6669, respectively; AIC, 1067 and 1126, respectively) generated a novel model that improved the predictive accuracy for survival in both sets (C-index, 0.7254 and 0.7117, respectively; AIC, 1047 and 1102, respectively). The model combining presence of NETs with the 7th edition AJCC TNM staging system also had improved predictive accuracy. CONCLUSIONS: NETs were an independent prognostic factor in PDAC and incorporation of NETs along with the standard TNM stating system refined risk-stratification and predicted survival in PDAC with improved accuracy.

Intrinsic Contact Between T and N Classifications in Resected Well-Moderately Differentiated Locoregional Pancreatic Neuroendocrine Neoplasms.

BACKGROUND: The role of N classification is controversial in several prognostication systems proposed for pancreatic neuroendocrine neoplasms (pNENs). The widely accepted modified European Neuroendocrine Tumor Society (mENETS) system suggests this contradiction may be related to T classification. METHODS: Data were collected retrospectively from 981 patients in the Surveillance, Epidemiology, and End Results (SEER) database (1973-2012; cohort 1) and 140 patients from the Pancreatic Cancer Institute of Fudan University (2006-2016; cohort 2). All patients had resected well- to moderately differentiated locoregional pNENs, whereby the mENETS system was adopted. Factors related to N1 classification and the association between N and T classifications were analyzed, and N classification prognosis based on T classification was assessed. RESULTS: In cohorts 1 and 2, tumor size (2-4 cm: p < 0.001 and p = 0.037, respectively; > 4 cm: p < 0.001 and p = 0.012, respectively) and tumors extending beyond the pancreas (p < 0.001 and p = 0.016, respectively), which are factors for T classification, affected N1 classification. For tumors limited to the pancreas, the N1 classification was associated with tumor size (p < 0.001 and p = 0.046, respectively) and predicted poor disease-specific survival (DSS), while for tumors extending beyond the pancreas, the N1 classification did not affect patient outcomes. Findings obtained with data from the SEER database were reproducible with our institutional data. CONCLUSIONS: N classification is associated with T classification, limiting the value of N1 classification for the pNENs tumor-node-metastasis system. A new risk model is necessary to predict patient outcomes and guide clinical practice for the prognosis of pNENs.

Tumor-Infiltrating Platelets Predict Postsurgical Survival in Patients with Pancreatic Ductal Adenocarcinoma.

BACKGROUND: Platelets are believed to promote tumor growth and metastasis in several tumor types. The prognostic role of blood platelets in pancreatic ductal adenocarcinoma (PDAC) remains controversial, and the prognostic value of tumor-infiltrating platelets (TIPs) remains unknown. METHODS: A total of 303 patients who underwent curative pancreatectomy for PDAC were enrolled from two independent centers in China and divided into three cohorts. Paired preoperative blood samples and surgical specimens from all patients were analyzed. The correlations between patient outcomes and preoperative blood platelet counts and the presence of TIPs, respectively, were analyzed. TIPs were identified by immunohistochemical staining of CD42b. Prognostic accuracy was estimated by concordance index (C-index) and Akaike information criterion (AIC). RESULTS: TIPs, but not preoperative blood platelet counts, were associated with overall survival (OS; all P < 0.001) and recurrence-free survival (RFS; all P < 0.001) in the training, testing, and validation sets. Positive CD42b expression predicted poor postsurgical survival. Incorporation of TIPs improved the predictive accuracy of the 8th edition American Joint Committee on Cancer (AJCC) tumor-node-metastasis (TNM) staging system for OS in each of the three cohorts (C-index: 0.7164, 0.7569, and 0.7050, respectively; AIC: 472, 386, and 1019, respectively). The new predictor system was validated by incorporating TIPs with the 7th edition AJCC TNM staging system (C-index: 0.7052, 0.7623, and 0.7157; AIC: 476, 386, and 1015). CONCLUSION: TIPs were an independent prognostic factor that could be incorporated into the AJCC TNM staging system to refine risk stratification and predict surgical outcomes of patients with PDAC.

Postoperative serum CA19-9, CEA and CA125 predicts the response to adjuvant chemoradiotherapy following radical resection in pancreatic adenocarcinoma.

OBJECTIVE: To evaluate the prediction of benefits from adjuvant chemoradiotherapy by postoperative serum CA19-9, CA125 and CEA. METHODS: The relations between benefits from adjuvant chemoradiotherapy and levels of postoperative serum CA19-9, CA125 and CEA were investigated in 804 pancreatic adenocarcinoma patients who received radical resection. RESULTS: Adjuvant chemoradiotherapy was an independent factor for late recurrence [12.2 vs. 8.5 months, P = 0.001 for recurrence free survival (RFS)] and long survival [23.7 vs. 17.0 months, P < 0.001 for overall survival (OS)] in resected pancreatic adenocarcinoma. Postoperative serum CA19-9, CA125 and CEA were independent risk predictors for poor surgical outcome in pancreatic adenocarcinoma (P < 0.001 for all). Adjuvant chemradiotherapy (hazard ratio: 0.359, 95% confidence interval: 0.253-0.510, P < 0.001 for OS; hazard ratio: 0.522, 95% confidence interval: 0.387-0.705, P < 0.001 for RFS) were confirmed to improve the surgical outcome in patients with abnormal levels of any one of the three postoperative markers, but not in patients with normal levels of the three postoperative markers. In the subgroup of patients with negative lymph node, its improvement of surgical outcome was also significant in patients with abnormal levels of any one of postoperative serum CA19-9, CA125 and CEA (hazard ratio: 0.412, 95% confidence interval: 0.244-0.698, P = 0.001 for OS; hazard ratio: 0.546, 95% confidence interval: 0.352-0.847, P = 0.007 for RFS). CONCLUSION: Postoperative serum CA19-9, CA125 and CEA could serve as predictors of response for adjuvant chemoradiotherapy even if the status of lymph nodes is negative.

The clinicopathological and prognostic significance of PD-L1 expression in pancreatic cancer: A meta-analysis.

BACKGROUND: Immunotherapy has shown promise against solid tumors. However, the clinical significance of programmed cell death 1 (PD-1) and programmed cell death ligand 1 (PD-L1) in pancreatic ductal adenocarcinoma (PDAC) remains unclear. This meta-analysis aimed to analyze the prognostic effect of PD-L1 in PDAC. DATA SOURCES: Electronic search of the PubMed, Cochrane Library and Web of Science was performed until December 2016. Through database searches, we identified articles describing the relationship between PD-L1 status and PDAC patient prognosis. Meta-analysis was performed to investigate the relationship between PD-1 and overall survival (OS). RESULTS: Nine studies with 989 PDAC patients were included for PD-L1 expression analysis. And 5 studies with 688 PDAC patients were included in the prognostic analysis. The PD-L1 positive rate measured by immunohistochemistry (IHC) was higher than that measured by polymerase chain reaction (PCR) (P < 0.001). PDAC patients with high expression levels of PD-L1 had significantly reduced OS (HR = 2.34; 95% CI: 1.78-3.08). Subgroup analysis showed that the prognostic effect of PD-L1 levels was similar between the IHC and PCR methods. The PD-L1 positive rate was associated with PDAC T stages; the PD-L1 positive rate in the T3-4 group was higher than that in the T1-2 group (OR = 0.37; P = 0.001). CONCLUSIONS: High PD-L1 expression levels predicted a poor prognosis in PDAC patients. Thus, PD-L1 status helps determine treatment in PDAC patients.

KLF17 Expression in Colorectal Carcinoma and Its Clinical Significance.

OBJECTIVE: To detect KLF17 expression in colorectal carcinoma (CRC) and to evaluate its effect on the prognosis of colorectal carcinoma. METHODS: Immunohistochemistry was performed to detect the expression of KLF17 in CRC and matched pericarcinous tissue,and the relationship between KLF17 expression and disease-free survival (DFS) was analyzed. RESULTS: Of 73 CRC patients, KLF17 expression was positive in 32 patients and negative in 41 patients. KLF17 expression rate was significantly lower in CRC tissue than in pericarcinous tissue (χ(2)=12.418, P=0.001). The DFS of KLF17-positive stage III colon cancer patients was (56.3±7.2) months (95% CI: 42-70 months), which was significantly longer than that [(32.3±5.5) months (95% CI: 22-43 months)] of KLF17-negative patients (P=0.039). CONCLUSION: KLF17 expression decreases in CRC tissue, and a positivie KLF17 expression predicts a better prognosis in stage III CRC patients.

Efficiency of Sunitinib in Chinese Patients with Advanced Progressive Pancreatic Neuroendocrine Tumor.

Objective To explore the efficiency of sunitinib in Chinese pancreatic neuroendocrine tumors (pNET) patients. Methods Advanced pNET patients who had accepted sunitinib treatment in the oncology department of PUMC Hospital from January 2009 to June 2015 after disease progression were enrolled in this study. Data collection included clinicopathological characteristics,medical therapies and outcomes. Results Eighteen pNET patients were collected. The overall response rate (ORR) was 27.7% and the disease control rate (DCR) was 83.3%. Nine patients received sunitinib as the first-line therapy and 9 as the second/post-second line. The median progression-free survival (mPFs)(12 month vs. 12 month;HR:0.92,95%CI:0.31-2.75,P=0.88),ORR (22.2% vs.33.3%;Χ(2)=0.055,P=0.98),and DCR (88.9% vs.77.8%;Χ(2)=0.4,P=0.98)showed no significant difference between first-line therapy and post-second line therapy. The mPFS of Ki-67≥10% and Ki-67<10% group patients was not significantly different (8 months vs. 13 months;HR:1.13,95% CI:0.34-3.77,P=0.845). The commonly reported adverse events included bone marrow suppression,diarrhea,roteinuria,hypertension,and rash. Conclusions First-line or second/post-second line sunitinib treatment has certain antitumor activity in Chinese patients with advanced pNET. The efficiency and commonly reported adverse events of Sunitinib are consistent with the known Western data.

[Chemotherapy risk assessment for elderly patients].

The incidence of cancer increases with age and most elderly patients will choose chemotherapy, and the complications of cytotoxic chemotherapy will be more common in these patients. Therefore, it is particularly important to predict the chemotherapy toxicity for the elderly patients. This review article summarizes the recent chemotherapy risk assessment tools for the elderly patients.

Role of Somatostatin Receptor 2 in Nonfunctional Pancreatic Neuroendocrine Tumors: Clinicopathological Analysis of 223 Cases and Whole Exome Sequencing of a Multifocal Case.

OBJECTIVES: Somatostatin receptors are commonly expressed in most pancreatic neuroendocrine tumors (pNETs), a rare type of pancreatic tumors with high heterogeneity. However, the role of somatostatin receptor 2 (SSTR2) has seldom been investigated separately in pNET. This retrospective study aims to evaluate the role of SSTR2 in the clinicopathological features and genomic background of nonfunctional and well-differentiated pNET. METHODS: A total of 223 cases of nonfunctional well-differentiated pNET were included, and the correlation between SSTR2 status and clinicopathological outcome was evaluated. In addition, we performed whole exome sequencing in SSTR2-positive and SSTR2-negative pNETs and identified that the 2 lesions harbored different mutational landscapes. RESULTS: Negative SSTR2 immunochemistry staining was significantly related to an earlier onset of disease, larger tumor size, advanced stage of American Joint Committee on Cancer, and tumor metastasis in lymph nodes and liver. Under pathological assessment, positive peripheral aggression, vascular invasion, and perineural invasion were markedly increased in SSTR2-negative cases. Moreover, SSTR2-negative patients exhibited significantly worse progression-free survival than SSTR2-positive patients (hazard ratio, 0.23; 95% confidence interval, 0.10-0.53; P = 0.001). CONCLUSIONS: Somatostatin receptor 2-negative nonfunctional pNET might represent a subtype of pNET with poor outcomes and evolve from a different genomic background.

A real-life treatment cohort of pancreatic neuroendocrine tumors: High-grade increase in metastases confers poor survival.

Background: Tumor grade determined by the Ki67 index is the best prognostic factor for pancreatic neuroendocrine tumors (PanNETs). However, we often observe that the grade of metastases differs from that of their primary tumors. This study aimed to investigate the frequency of grade changes between primary tumors and metastases, explore its association with clinical characteristics, and correlate the findings with the prognosis. Methods: Six hundred forty-eight patients with pancreatic neuroendocrine neoplasms treated at Fudan University Shanghai Cancer Center were screened for inclusion, and 103 patients with PanNETs who had paired primary tumors and metastases with an available Ki67 index were included. Re-evaluation of Ki67 was performed on 98 available samples from 69 patients. Results: Fifty cases (48.5%) had a Ki67 index variation, and 18 cases (17.5%) displayed a grade increase. Metachronous metastases showed significantly higher Ki67 index variation than synchronous metastases (P=0.028). Kaplan-Meier analyses showed that high-grade metastases compared to low-grade primary tumors were significantly associated with decreased progression-free survival (PFS, P=0.012) and overall survival (OS, P=0.027). Multivariable Cox regression analyses demonstrated that a low-grade increase to high-grade was an unfavorable and independent prognostic factor for PFS and OS (P=0.010, and P=0.041, respectively). Conclusions: A high-grade increase in metastases was an unfavorable predictor of PanNETs, which emphasized the importance of accurate pathological grading and could provide a reference for clinical decision-making.

Bidirectional and dynamic interaction between the microbiota and therapeutic resistance in pancreatic cancer.

Pancreatic ductal adenocarcinoma is one of the most lethal malignancies and is known for its high resistance and low response to treatment. Cancer treatments can reshape the microbiota and in turn, the microbiota influences the therapeutic efficacy by regulating immune response and metabolism. This crosstalk is bidirectional, heterogeneous, and dynamic. In this review, we elaborated on the interactions between the microbiota and therapeutic resistance in pancreatic ductal adenocarcinoma. Regulating the microbiota in pancreatic tumor microenvironment may not only generate direct anti-cancer but also synergistic effects with other treatments, providing new directions in cancer therapy.

Neutrophil Extracellular Traps and Macrophage Extracellular Traps Predict Postoperative Recurrence in Resectable Nonfunctional Pancreatic Neuroendocrine Tumors.

Background: Extracellular traps (ETs) and tumor-infiltrating immune cells can contribute to disease progression. The clinical significance of tumor-infiltrating neutrophils and macrophages and related extracellular traps in pancreatic neuroendocrine tumors (pNETs) has not been fully elucidated. This study aimed to explore the prognostic value of tumor infiltration and ET formation by neutrophils and macrophages in pNETs. Methods: A total of 135 patients with radical resection of nonfunctional pNETs were analyzed retrospectively. Immunohistochemistry and immunofluorescence were utilized to stain tumor tissue sections. The recurrence-free survival (RFS) of subgroups determined by Kaplan-Meier analysis was compared with the log-rank test. Univariate and multivariate Cox regression analyses were used to identify independent prognostic factors. A nomogram was established to predict 3-year RFS. Results: Patients with high tumor-infiltrating neutrophils or macrophages or positive expression of neutrophils ETs or macrophage ETs displayed worse RFS (all p<0.05). Moreover, univariate and multivariate Cox regression analyses showed that neutrophil and macrophage infiltration and ETs were independent prognostic factors for RFS (all p<0.05). A combined parameter including WHO grade, TNM stage, tumor-infiltrating neutrophils and macrophages, and neutrophil and macrophage ETs had the highest C-index (0.866) and lowest Akaike information criteria (326.557). The calibration plot of nomogram composed of the combined parameter exhibited excellent prognostic values for 3-year RFS. Conclusions: Infiltration and ETs by neutrophils and macrophages can be used as biological indicators of patient prognosis, suggesting the treatment potential for targeting those in nonfunctional pNETs.

A novel risk factor panel predicts early recurrence in resected pancreatic neuroendocrine tumors.

BACKGROUND: Pancreatic neuroendocrine tumors (PanNETs) are indolent pancreatic tumors derived from neuroendocrine cells in pancreatic islets. To date, reliable predictors for identifying patients at high risk for recurrence after curative cancer resection are lacking. We aimed to determine independent predictors for high-risk PanNETs and patient outcomes after surgery. METHODS: We analyzed relevant clinicopathological parameters in 319 consecutive patients of derivation cohort 1 and 106 patients of validation cohort 2 who underwent pancreatectomy and were diagnosed with PanNETs. Association of tumor characteristics with recurrence-free survival (RFS) and overall survival (OS) was evaluated using Cox regression. RESULTS: PanNET grade 3 (G3), pancreatic duct dilatation, and perineural invasion were independent prognostic factors for RFS and were significantly associated with early recurrence (within 1.5 years) of PanNETs after curative resection (P = 0.019, P < 0.001, and P < 0.001, respectively). Using these factors, we established a novel risk factor panel (R-panel), which predicted early recurrence (P < 0.001, HR = 15.02, 95% CI 5.76-39.19). Predictive accuracy of this R-panel was favorable, with a C-index of 0.853, higher than AJCC TNM staging (0.713). We further built an integrated staging system combining R-panel scoring and TNM staging, which improved predictive probability of TNM staging. Finally, we showed that adjuvant therapy with long-acting somatostatin analogs (SSAs) significantly reduced postoperative recurrence (P < 0.001) and prolonged long-term survival (P = 0.021) in patients with the above risk factors. CONCLUSION: We identified a novel risk factor panel, which includes PanNET G3, pancreatic duct dilatation, and perineural invasion; this panel predicted early recurrence of PanNETs after curative resection. Patients with these risk factors can benefit from adjuvant therapy with SSAs.

Molecular drivers and cells of origin in pancreatic ductal adenocarcinoma and pancreatic neuroendocrine carcinoma.

Pancreatic cancer is one of the most common causes of cancer-related deaths worldwide. The two major histological subtypes of pancreatic cancer are pancreatic ductal adenocarcinoma (PDAC), accounting for 90% of all cases, and pancreatic neuroendocrine neoplasm (PanNEN), which makes up 3-5% of all cases. PanNEN is classified into well-differentiated pancreatic neuroendocrine tumor and poorly-differentiated pancreatic neuroendocrine carcinoma (PanNEC). Although PDAC and PanNEN are commonly thought to be different diseases with distinct biology, cell of origin, and genomic abnormalities, the idea that PDAC and PanNEC share common cells of origin has been gaining support. This is substantiated by evidence that the molecular profiling of PanNEC is genetically and phenotypically related to PDAC. In the current review, we summarize published studies pointing to common potential cells of origin and speculate about how the distinct paths of differentiation are determined by the genomic patterns of each disease. We also discuss the overlap between PDAC and PanNEC, which has been noted in clinical observations.

Active surveillance in metastatic pancreatic neuroendocrine tumors: A 20-year single-institutional experience.

BACKGROUND: Pancreatic neuroendocrine tumors (PanNETs) are heterogeneous and indolent; systemic therapy is not essential for every patient with metastatic PanNET. The National Comprehensive Cancer Network guidelines state that delaying treatment is an option for PanNET with distant metastasis, if the patient has stable disease. However, specific factors that influence surveillance were not mentioned. In addition, data regarding the period of active surveillance in patients with metastatic PanNET are lacking. AIM: To specifically determine factors influencing active surveillance in patients with liver metastatic nonfunctioning PanNETs (NF-PanNETs). METHODS: Seventy-six patients with liver metastatic NF-PanNETs who received active surveillance from a high-volume institution were enrolled. Time to disease progression (TTP) and time to initiation of systemic therapy were determined. RESULTS: Thirty-one (40.8%) patients had recurrent liver disease after R0 resection; 45 (59.2%) were diagnosed with liver metastasis. The median follow-up period was 42 mo and 90.7% patients were observed to have disease progression. The median TTP (mTTP) was 10 mo. Multivariate analysis showed that the largest axis of the liver metastasis > 5 mm (P = 0.04), non-resection of the primary tumor (P = 0.024), and T3-4 stage (P = 0.028) were associated with a shorter TTP. The mTTP in patients with no risk factors was 24 mo, which was significantly longer than that in patients with one (10 mo) or more (6 mo) risk factors (P < 0.001). A nomogram with three risk factors showed reasonable calibration, with a C-index of 0.603 (95% confidence interval: 0.47-0.74). CONCLUSION: Active surveillance may only be safe for metastatic NF-PanNET patients with favorable risk factors, and other patients progressed rapidly without treatment. Further studies with a larger sample size and a control group are needed.

TET1 downregulates epithelial-mesenchymal transition and chemoresistance in PDAC by demethylating CHL1 to inhibit the Hedgehog signaling pathway.

Chemoresistance is a major obstacle to prolonging pancreatic ductal adenocarcinoma (PDAC) patient survival. TET1 is identified as the most important epigenetic modification enzyme that facilitates chemoresistance in cancers. However, the chemoresistance mechanism of TET1 in PDAC is unknown. This study aimed to determine the role of TET1 in the chemoresistance of PDAC. TET1-associated chemoresistance in PDAC was investigated in vitro and in vivo. The clinical significance of TET1 was analyzed in 228 PDAC patients by tissue microarray profiling. We identified that TET1 downregulation is caused by its promoter hypermethylation and correlates with poor survival in PDAC patients. In vitro and in vivo functional studies performed by silencing or overexpressing TET1 suggested that TET1 is able to suppress epithelial-mesenchymal transition (EMT) and sensitize PDAC cells to 5FU and gemcitabine. Then RNA-seq, whole genome bisulfite sequencing (WGBS) and ChIP-seq were used to explore the TET1-associated pathway, and showed that TET1 promotes the transcription of CHL1 by binding and demethylating the CHL1 promoter, which consequently inhibits the Hedgehog pathway. Additionally, inhibiting Hedgehog signaling by CHL1 overexpression or the Hedgehog pathway inhibitor, GDC-0449, reversed the chemoresistance induced by TET1 silencing. Regarding clinical significance, we found that high TET1 and high CHL1 expression predicted a better prognosis in resectable PDAC patients. In summary, we demonstrated that TET1 reverses chemoresistance in PDAC by downregulating the CHL1-associated Hedgehog signaling pathway. PDAC patients with a high expression levels of TET1 and CHL1 have a better prognosis.