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Background: Pancreatic ductal adenocarcinoma (PDAC) patients have improved prognosis after neoadjuvant therapy (NAT). However, there is a lack of biomarkers to predict the pathological response preoperatively. We evaluated the predictive value of multiple biomarkers, including inflammatory biomarkers, for predicting the pathological responses. Methods: We respectively reviewed the records of patients with localized PDAC who underwent NAT followed by resection between January 2017 and May 2021 at the First Affiliated Hospital of Naval Medical University. The patients were divided into the major pathological response (MPR) and non-MPR groups, according to the tumor regression grade. Univariate and multivariate predictors of MRP were explored. The predictive factors identified on multivariate analysis were used to establish a nomogram prognostic model, which was evaluated using the Decision Curve Analysis (DCA). Results: A total of 150 patients, including 21 in the MPR and 129 in the non-MPR group, were analyzed. In the multivariate analysis of the MRP group, normal CA19-9 level (

Background The superior mesenteric artery-first approach has been proved superior in pancreatoduodenectomy compared with the standard procedure. It is unclear whether similar benefits could be obtained in distal pancreatectomy with celiac axis resection. Methods Perioperative and survival outcomes of patients who underwent distal pancreatectomy with celiac axis resection with the modified artery-first approach or traditional approach between January 2012 and September 2021 were compared. Results The entire cohort comprised 106 patients (modified artery-first approach, n = 35; traditional approach, n = 71). The most common complication was postoperative pancreatic fistula (n = 18, 17.0 per cent), followed by ischaemic complications (n = 17, 16.0 per cent) and surgical site infection (n = 15, 14.0 per cent). Intraoperative blood loss (400 versus 600 ml, P = 0.017) and intraoperative transfusion rate (8.6 versus 29.6 per cent, P = 0.015) were lower in the modified artery-first approach group compared with the traditional approach group. A higher number of harvested lymph nodes (18 versus 13, P = 0.030) and R0 resection rate (88.6 versus 70.4 per cent, P = 0.038) and a lower incidence of ischaemic complications (5.7 versus 21.1 per cent, P = 0.042) was observed in the modified artery-first approach group compared with the traditional approach group. In multivariable analysis, the modified artery-first approach (OR 0.006, 95 per cent c.i., 0 to 0.447; P = 0.020) was protective against ischaemic complications. Conclusions Compared with the traditional approach, the modified artery-first approach was associated with lower blood loss and fewer ischaemic complications, and a higher number of harvested lymph nodes and R0 resection rate. Thus, it might improve the safety, staging and prognosis of distal pancreatectomy with celiac axis resection for pancreatic cancer.

Positive resection margin indicates worse prognosis. The present study identified the independent risk factors of R1 resection in pancreaticoduodenectomy (PD) and distal pancreatosplenectomy (DP) for patients with pancreatic ductal adenocarcinoma (PDAC).Consecutive patients who were operated from 1st December 2017 to 30th December 2018 were analyzed retrospectively. A standardized pathological examination with digital whole-mount slide images (DWMSIs) was utilized for evaluation of resection margin status. R1 was defined as microscopic tumor infiltration within 1 mm to the resection margin. The potential risk factors of R1 resection for PD and DP were analyzed separately by univariate and multivariate logistic regression analyses.For the 192 patients who underwent PD, and the 87 patients who underwent DP, the R1 resection rates were 31.8% and 35.6%, respectively. Univariate analysis on risk factors of R1 resection for PD were tumor location, lymphovascular invasion, N staging, and TNM staging; while those for DP were T staging and TNM staging. Multivariate logistic regression analysis showed the location of tumor in the neck and uncinate process, and N1/2 staging were independent risk factors of R1 resection for PD; while those for DP were T3 staging.The clarification of the risk factors of R1 resection might clearly make surgeons take reasonable decisions on surgical strategies for different surgical procedures in patients with PDAC, so as to obtain the first attempt of R0 resection.

Objective:. To investigate the effect of long-acting octreotide as adjuvant therapy in the prevention of tumor recurrence in patients with grade 2 pancreatic neuroendocrine tumors (pNETs) after radical resection. Methods:. The postoperative follow-up data of 130 patients with resectable G2 pNET treated in the Changhai Hospital from 2008 to 2018 were retrospectively analyzed: 59 patients received long-acting octreotide as adjuvant therapy for 6 to 12 months (Oct group) and 71 patients received active follow-up (control group), both of which began after the radical resection, with the primary observation endpoint of disease-free survival (DFS) and the secondary study endpoint of overall survival. Results:. The median age of the patients in the Oct group and control group was 52 and 54 years, respectively. There were 28 male cases (47.5%) and 33 male cases (46.5%) in the 2 groups. The median maximum tumor diameter was 3.5 and 3.0 cm, respectively; lymph node metastasis was positive in 13 cases (22.0%) and 9 cases (12.7%); there was peripancreatic nerve invasion in 11 cases (18.6%) and 6 cases (8.5%). Survival analysis revealed that there were significant differences in 2-year DFS% (98.3% vs 88.7%, P = .0371) and 3-year DFS% (96.6% vs 85.9%, P = .0498) between the Oct group and control group. Long-acting octreotide treatment was found to reduce the risk of 3-year recurrence of G2 pNET after radical resection (HR = 0.2, P = .044) with the application of inverse-probability-of-treatment weighted to balance the limited data bias. Conclusion:. Using long-acting octreotide as adjuvant therapy for G2 pNET patients after radical surgery may improve the rate of 3y-DFS, but the benefit needs to be confirmed in a well-designed random control clinical trial.

Background Neoadjuvant chemotherapy may benefit patients with pancreatic ductal adenocarcinoma with resectable and borderline disease. Inappropriate use of neoadjuvant therapy, however, may lead to the loss of therapeutic opportunities. Until an effective prediction model of individual drug sensitivity is established, no accurate model exists to help surgeons decide on the appropriate use of neoadjuvant chemotherapy. We hypothesized that early recurrence in patients undergoing upfront, early resection may be an indication for neoadjuvant chemotherapy. Therefore, we aimed to use preoperative clinical parameters to establish a model of early recurrence to select patients at high risk for neoadjuvant chemotherapy. Methods Patients who underwent resection for pancreatic ductal adenocarcinoma between January 2014 and November 2017 were analyzed retrospectively. After the minimum P-value approach, the patients were divided into three groups: early recurrence, middle recurrence, and late/non-recurrence. Preoperative clinicopathologic factors that could predict early recurrence were included in a Cox proportional hazards regression model for univariate and multivariate analyses. The factors related to early recurrence were included to establish nomogram and decision tree models, which were then validated in 68 patients. Results We found that 235 (72.5%) of 324 patients had recurrence with a median recurrence-free survival of 210 days. The early recurrence, middle recurrence, and late/non-recurrence groups differed in preoperative carbohydrate antigen 19-9 and carcinoembryonic antigen levels, “resectability” on cross-sectional imaging, resection requiring a vascular resection, T stage, tumor size, and adjuvant chemotherapy. The best cutoff value of early recurrence was the first 162 days postoperatively. Univariate and multivariate analyses showed that selected preoperative chief complaints, lymph node enlargement and resectability on cross-sectional imaging, preoperative carbohydrate antigen 19-9 levels >210 kU/L, and a neutrophil/lymphocyte ratio >4.2 were independent predictors for early recurrence. Conclusion We have successfully built a prediction model of early recurrence of patients with pancreatic ductal adenocarcinoma with the optimal cutoff early-recurrence value of 162 days. Our nomogram and decision tree models may be used to select those at high risk for early recurrence to guide preoperative decision-making concerning the use of neoadjuvant therapy in those patients who have “resectable” disease and not only the more classic criteria of borderline resectability.

This study aimed to explore patterns of the treatment strategies of pancreatic ductal adenocarcinoma based on 2000 consecutive cases of a prospective database since 2012 to obtain new insights for future directions.Among 2000 patients enrolled in this study, 210 patients were excluded, and 710, 521, and 559 patients were treated between 2012 and 2015 (group 1), between 2016 and 2017 (group 2), and between 2018 and 2019 (group 3), respectively. Patient clinicopathologic and biological factors, and perioperative outcomes were used to assess the prognostic factors.The median survival for all patients with pancreatic ductal adenocarcinoma was 21.7 months (1-year survival, 75.0%; 2-year survival, 43.7%; 5-year survival, 19.7%). Group 3 had a better survival outcome than groups 1 and 2 (median survival time: 23 versus 20.5 and 21.1 months). The proportion of patients younger than 65 gradually increased over time, as did the use of systemic chemotherapy and postoperative adjuvant radiotherapy. The tendency for early diagnosis (lower CA19-9 and CEA levels, smaller size, and earlier N stage), use of chemotherapy and radiotherapy, early recovery (lesser hospital stay and Clavien-Dindo grade3), absence of abdominal pain, younger age, length of operation ≤3 h, and pathological factors (absence of lymphovascular invasion, peripancreatic fat infiltration and neural invasion, higher differentiation) were related to patients' survival. Multivariable analysis for prognosis revealed that tumor biological factors (increased preoperative serum CA19-9 level, tumor size, tumor differentiation, N stage, and presence of lymphovascular invasion and neural invasion), chemotherapy, radiotherapy, abdomen pain, operation period, length of stay, and length of operation correlated with patients' survival.Systemic therapy, including chemotherapy and radiotherapy, has gradually improved the prognosis after operative resection for pancreatic ductal adenocarcinoma. Neoadjuvant therapy is also beneficial to improve the prognosis to a certain extent. The enhanced recovery after surgery (ERAS) policies and the specific assessment of postoperative pancreatic fistula (POPF) risk may be related to reduced hospital stays and the reduction of serious complications. These advancements show that the concept of systemic therapy has been accepted and actively applied by Chinese medical institutions.

Background About 25–37% of resectable pancreatic ductal adenocarcinoma (PDAC) had a great chance of early recurrence after radical resection, which is mainly due to preoperative micrometastasis. We herein demonstrated the profiles of ctDNA in resectable PDAC and use of ctDNA to identify patients with potential micrometastasis. Methods A total of 113 and 44 resectable PDACs were enrolled in discovery and validation cohorts, separately. A panel containing 50 genes was used to screen ctDNA by an NGS-based assessment with high specificity. Results In the discovery cohort, the overall detection rate was 38.05% (43/113). Among positive ctDNA, KRAS mutation had the highest detection rate (23.01%, 26/113), while the others were Conclusions This study demonstrated that plasma KRAS mutations, especially KRAS G12D mutation, served as a useful predictive biomarker for prognosis of resectable PDAC. More importantly, due to high correlation with micrometastasis, preoperative detection of plasma KRAS G12D mutation helps in optimising surgical selection of resectable PDAC.

Supplemental digital content is available in the text., Objective The objective of this study was to explore the exact relationship between the arterial radiomics score (rad-score) and lymph node (LN) metastasis in pancreatic ductal adenocarcinoma (PDAC). Methods A total of 225 patients with pathologically confirmed PDAC who underwent multislice computed tomography within 1 month of resection from December 2016 to August 2017 were retrospectively studied. For each patient, 1029 radiomics features of arterial phase were extracted, which were reduced using the least absolute shrinkage and selection operator logistic regression algorithm. Multivariate logistic regression models were used to analyze the association between the arterial rad-score and LN metastasis. Results Lymph node–negative and LN-positive patients accounted for 107 (47.56%) and 118 (52.44%) of the cohort, respectively. The rad-score, which consisted of 12 selected features of the arterial phase, was significantly associated with LN status (P < 0.05). Univariate analysis revealed that the arterial rad-score and T stage were independently and positively associated with risk of LN metastasis (P < 0.05). Multivariate analyses revealed a significant association between the arterial rad-score and the LN metastasis (P < 0.0001). Higher arterial rad-score was associated with LN metastasis (P for trend

Background: Positive resection margin indicates worse prognosis. The present study identified the independent risk factors of R1 resection in pancreaticoduodenectomy (PD) and distal pancreatosplenectomy (DP) for patients with pancreatic ductal adenocarcinoma (PDAC).Methods：Consecutive patients who were operated from 1st December 2017 to 30th December 2018 were analyzed retrospectively. A standardized pathological examination with digital whole-mount slide images (DWMSIs) was utilized for evaluation of resection margin status. R1 was defined as microscopic tumor infiltration within 1 mm to the resection margin. The potential risk factors of R1 resection for PD and DP were analyzed separately by univariate and multivariate logistic regression analyses. Results：For the 240 patients who underwent PD, and the 146 patients who underwent DP, the R1 resection rates were 30.8% and 35.6 %, respectively. Univariate analysis on risk factors of R1 resection for PD were tumor location, absence of tumor necrosis, N staging, and TNM staging; while those for DP were perineural invasion, T staging, and TNM staging. Multivariate logistic regression analysis showed the location of tumor in the neck and uncinate process, and N1/2 staging were independent risk factors of R1 resection for PD; while those for DP were T3/4 staging. Conclusions：The clarification of the risk factors of R1 resection might clearly make surgeons take reasonable decisions on surgical strategies for different surgical precedures in patients with PDAC, so as to obtain the first attempt of R0 resection.

Background The differential diagnosis of pancreatic ductal adenocarcinoma (PDAC) from chronic pancreatitis (CP) is clinically challenging due to a lack of minimally invasive diagnosis methods. MicroRNAs (miRNAs) derived from small extracellular vesicles (EVs) in the blood have been reported as a promising diagnosis biomarker for various types of cancer. However, blood small EV miRNA signatures and their diagnostic value to differentiate between PDAC and CP remain to be determined. Methods In this study, 107 patients with PDAC or CP were recruited, and 90 patients were finally enrolled for a training cohort (n = 48) and test cohort (n = 42). Small RNA sequencing was used to assess the expression of blood small EV miRNAs in these patients. Results The linear model from the differentially expressed blood small EV miR‐95‐3p divided by miR‐26b‐5p showed an average sensitivity of 84.1% and an average specificity of 96.6% to identify PDAC from CP in the training cohort and the test cohort, respectively. When the model was combined with serum carbohydrate antigen 19‐9 (CA19‐9), the average sensitivity increased to 96.5%, and the average specificity remained at 96.4% of both cohorts, which demonstrated the best performance of all the published biomarkers for distinguishing between PDAC and CP. The causal analysis performed using the Bayesian network demonstrated that miR‐95‐3p was associated with a “consequence” of “cancer” and miR‐26b‐5p as a “cause” of “pancreatitis.” A subgroup analysis revealed that blood small EV miR‐335‐5p/miR‐340‐5p could predict metastases in both cohorts and was associated with an overall survival (p = 0.020). Conclusions This study indicated that blood small EV miR‐95‐3p/miR‐26b‐5p and its combination with serum levels of CA19‐9 could separate PDAC from CP, and miR‐335‐5p/miR‐340‐5p was identified to associate with PDAC metastasis and poor prognosis. These results suggested the potentiality of blood small EV miRNAs as differential diagnosis and metastases biomarkers of PDAC., The challenge of separating pancreatic ductal adenocarcinoma (PDAC) from chronic pancreatitis (CP) is the lack of minimally invasive clinically diagnostic methods. Blood small EV miR‐95‐3p/miR‐26b‐5p and its combination with CA19‐9 serum levels were discovered and validated to separate PDAC from CP. These results suggested the potentiality of blood small EV miRNAs as differential diagnosis biomarkers of PDAC.

Background/Objectives: The present study identified the independent risk factors of R1 resection in pancreaticoduodenectomy (PD) and distal pancreatosplenectomy (DP) for patients with pancreatic ductal adenocarcinoma (PDAC).Methods：Consecutive patients who were operated from 1st December 2017 to 30th December 2018 with curative intent were analyzed retrospectively. A standardized pathological examination with digital whole-mount slide images (DWMSIs) was utilized for the resection margin status. R1 was defined as microscopic tumor infiltration within 1 mm to the resection margin. The potential risk factors of R1 resection for PD and DP were analyzed separately by univariate and multivariate logistic regression analyses. Results：For the 240 patients who underwent PD, and the 146 patients who underwent DP, the R1 resection rates were 30.8% and 35.6 %, respectively. Univariate analysis on risk factors of R1 resection for PD were tumor location, absence of tumor necrosis, N staging, and TNM staging; while those for DP were perineural invasion, T staging, and TNM staging. Multivariate logistic regression analysis showed the location of tumor in the neck and uncinate process, and N1/2 staging were independent risk factors of R1 resection for PD; while those for DP were T3/4 staging. Conclusions：The clarification of the risk factors of R1 resection might clearly make surgeons take better decisions on surgical strategies for different surgical precedures in patients with PDAC.

Chromatin accessibility plays an essential role in controlling cellular identity and the therapeutic response of human cancers. However, the chromatin accessibility landscape and gene regulatory network of pancreatic cancer are largely uncharacterized. Here, we integrate the chromatin accessibility profiles of 84 pancreatic cancer organoid lines with whole-genome sequencing data, transcriptomic sequencing data and the results of drug sensitivity analysis of 283 epigenetic-related chemicals and 5 chemotherapeutic drugs. We identify distinct transcription factors that distinguish molecular subtypes of pancreatic cancer, predict numerous chromatin accessibility peaks associated with gene regulatory networks, discover regulatory noncoding mutations with potential as cancer drivers, and reveal the chromatin accessibility signatures associated with drug sensitivity. These results not only provide the chromatin accessibility atlas of pancreatic cancer but also suggest a systematic approach to comprehensively understand the gene regulatory network of pancreatic cancer in order to advance diagnosis and potential personalized medicine applications.

Purpose The study aimed to investigate the potential benefit of more than 4 courses of S1 adjuvant chemotherapy for patients with pancreatic ductal adenocarcinoma (PDAC) after surgery. Method Data were retrospectively collected from consecutive patients who underwent S-1 adjuvant chemotherapy following curative pancreatectomy between January 2016 and December 2018. Four-courses and > 4 courses cohorts were compared for overall survival (OS) as a primary outcome, and relapse-free survival (RFS) and adverse event incidence as secondary outcomes. Results Four-courses and > 4 courses cohorts comprised 99 patients and 64 ones, respectively. TNM stage (stage II vs. I: HR, 2.125; 95% CI, 1.164–4.213; P = 0.015), duration of S-1 administration (4 vs. > 4 courses: HR, 3.113; 95% CI, 1.531–6.327; P = 0.002) and tumor grade (G3 vs. G1/2: HR, 3.887; 95% CI, 1.922–7.861; P 4 courses cohort was significantly prolonged compared with that of 4 courses cohort (4 vs. > 4 courses: HR, 2.284; 95% CI, 1.197–4.358; P = 0.012), especially for patients in TNM stageII (4 vs. > 4 courses: HR, 2.906; 95% CI, 1.275–6.623; P = 0.011).RFS and adverse events incidence did not signifcantly difer between both cohorts. Conclusion Prolonged duration of S-1 intake is beneficial to prognosis of patients with PDAC resection.

Additional file 1: Supplementary Table 1. Univariate and multivariable Cox regression analyses of all clinicopathological features evaluated of patients with PDAC.

Background/Objectives: The present study identified the independent risk factors of R1 resection in pancreaticoduodenectomy (PD) and distal pancreatosplenectomy (DP) for patients with pancreatic ductal adenocarcinoma (PDAC).Methods：Consecutive patients who were operated from December 2017 to 2018 with curative intent were analyzed retrospectively. A standardized pathological examination with digital whole-mount slide images (DWMSIs) was utilized for the resection margin status. R1 was defined as microscopic tumor infiltration within 1 mm to the resection margin. The potential risk factors of R1 resection for PD and DP were analyzed separately by univariate and multivariate logistic regression analyses. Results：For the 240 patients who underwent PD, and the 142 patients who underwent DP, the R1 resection rates were 30.8% and 35.6 %, respectively. Univariate analysis on risk factors of R1 resection for PD were tumor location, absence of tumor necrosis, N staging, TNM staging, and surgical type of PD; while those for DP were nerve invasion, T staging, and TNM staging. Multivariate logistic regression analysis showed that the risk factors of R1 resection for PD were tumor location (neck vs. head; uncinate process vs. head) and N staging, while those for DP were T staging .Conclusions：The location of tumor in the neck and uncinate process, and N1/2 staging were independent risk factors of R1 resection for PD; while those for DP were T3/4 staging.

524 Background: PDAC is a cancer of high mortality. Accurate and cost-effective PCR assays detecting diagnostic and prognostic PDAC markers in blood are desirable for conducting PDAC screening in high-risk populations, evaluating treatments for patients and surveying for post-treatment relapse. Methods: We combined PDAC-diagnosing ctDNA methylation markers with PDAC-driving Kras mutations as targets to develop said PCR tests. Methylation markers were previously validated to classify PDAC plasma at a high accuracy by a targeted methylation sequencing assay. Seven known PDAC driver mutations in KRas exon2 were selected. Taqman-based quantitative methylation-specific PCR (MSP) and ARMS PCR were designed for methylation markers and KRas mutations, respectively, and were validated for technical performances. A step of pre-amplification of input DNA by conventional PCR was included prior to quantitative PCR to improve sensitivity. Over 200 clinical PDAC and control tissue and plasma samples were used to determine their analytical performances in classifying PDAC plasma. Results: All targets were detected at a limit-of-detection of 0.25% or better on standards DNA in PCR. To test clinical plasma samples, methylation markers were first filtered by comparing their levels in PDAC-, para-tumor tissues and whole blood cells. Twenty-four most discriminatory markers for PDAC tissues were selected and used to classify 110 PDAC plasma samples from equal number of normal samples. They were evaluated for their sensitivity at a pre-set specificity of 90%. The 4 best-performing markers were selected to build and cross-validate a general-linear-model (GLM) PDAC classifier, which achieved a sensitivity of 66% at 90% specificity (AUC = 0.829) in cross-validation. Adding status of KRas mutations further improved prediction accuracy by increasing sensitivity to 75% (AUC = 0.89), demonstrating the methylation markers and KRas mutations complement each other in detection PDAC plasma. Conclusions: Our results suggest that a small number of our DNA methylation markers can classify PDAC plasma at a reasonably high accuracy by MSP. Incorporating KRas driver mutations further improved classification accuracy. Together they are promising to be further translated into diagnostics for PDAC early screening, treatment assessment and postoperative surveillance.

Few patients with pancreatic cancer may be candidates for immediate surgical resection at the initial diagnosis. Even if patients with borderline resectable pancreatic cancer (BRPC), micrometastases may occur before surgery. Therefore, neoadjuvant therapy is vital for improved survival, which has been confirmed in previous studies that neoadjuvant chemotherapy with or without radiotherapy provides superior overall compared with upfront surgery. However, question of whether the addition of radiotherapy to neoadjuvant chemotherapy can improve prognosis compared with chemotherapy alone is a challenging matter. Moreover, most of previous studies only adopted conventional radiotherapy as the neoadjuvant modality though stereotactic body radiation therapy (SBRT) has been proven effective and commonly employed in pancreatic cancer. Also, no studies have evaluated the efficacy of S-1 as the neoadjuvant chemotherapy regimen for BRPC albeit similar prognosis has been found between S-1 and gemcitabine in advanced pancreatic cancer. Hence, the aim of this study is to investigate whether neoadjuvant chemotherapy plus SBRT results in better outcomes compared with neoadjuvant chemotherapy alone and also compare the efficacy of gemcitabine plus nab-paclitaxel with SBRT and S-1 plus nab-paclitaxel with SBRT. Patients with biopsy and radiographically confirmed BRPC, no prior treatment and severe morbidities are enrolled. They will be randomly allocated into three groups: neoadjuvant gemcitabine plus nab-paclitaxel, neoadjuvant gemcitabine plus nab-paclitaxel with SBRT and neoadjuvant S-1 plus nab-paclitaxel with SBRT. Standard doses of gemcitabine and nab-paclitaxel are used. The radiation dose of SBRT is 7.5-8Gy/f for 5 fractions. Surgical resection will be performed 3 weeks after SBRT. Artery first approach pancreaticoduodenectomy or radical antegrade modular pancreatosplenectomy will be used for the tumor in the head or body and tail of the pancreas, respectively. The primary endpoint is overall survival. The secondary outcomes are disease free survival, pathological complete response rate, R0 resection rate and incidence of adverse effects. If results show the survival benefits of neoadjuvant chemotherapy plus SBRT and similar outcomes between S-1 and gemcitabine, it may provide evidence of clinical practice of this modality for BRPC. The study has been registered in ClinicalTrial.gov ( NCT03777462 ).

BACKGROUND Pancreatic ductal adenocarcinoma (PDAC) is recognized as the most lethal solid malignancies with very few therapeutic options. Until very recently, FDA approved the first molecularly targeted therapy with the PARP inhibitor Olaparib for pancreatic cancer patients with germline mutations on BRCA1/2, two types of homologous recombination (HR)/DNA damage repair (DDR) genes. In addition, the sensitivity of platinum-based chemotherapy and anti-PD-1 antibodies have been connected with DDR spectrum. However, the genetic landscape of PDAC is mainly based on data from Caucasian population. In this study, we sought to explore the germline mutation spectrum of DDRs in oriental PDAC for clinical practice. METHODS Germline DNA extracted from 256 Asian peri ampullary cancer patients (201 PDAC, 20 adenosquamous carcinoma, and 35 vater periampullary carcinoma) underwent whole exome sequencing. The mean depth of sequencing was 67 X. 229 DDR genes were focused for variant callings using the GATK and its pathogenicity according to the guidelines from ACMG. Pathogenic or likely pathogenic(P/LP) were further analyzed. RESULTS Pathogenic variants were identified in 26 of 256 patients (10.2%),and one patient had mutations in two genes. The 27 pathogenic mutations occurred in 16 different genes,including ERCC2 (n=4), OGG1 (n=4), PALB2 (n=3), FAN1 (n=3), RAD54L (n=2), WRN (n=1), POLH (n=1), MUTYH (n=1), MSH6 (n=1), MLH3 (n=1), LIG1 (n=1), ERCC6 (n=1), CHEK2 (n=1), BRCA2 (n=1), BRCA1 (n=1), and ATM (n=1). The detailed gene profiles were mainly involved in five pathways, Homologous recombination(HR), Fanconi anemia(FA), Mismatch repair(MMR), Base excision repair(BER)and Nucleotide excision repair(NER. Of note, two mutations MSH6 c.261-1G>A and BRCA2 c.3912_3916del, were first reported to be associated with cancer and classified as likely pathogenic owing to their frameshift variant or splice site and low frequencies of occurrence. To determine the difference of germline DDR mutation landscape between oriental and American populations, we compared our cohort with American cohorts from Yurgelun and TCGA. The BRCA1/2 germline mutations were found at low levels in our cohort (0.8%) compared to the American cohorts (2.4~2.7%), Furthermore, the whole DDR mutations exhibited highest proportion [10.5% (27/256) from our study, compared with 7.3% (21/289) from Yurgelun, and 5.4% (10/185) from TCGA, respectively]. CONCLUSION In conclusion,our results characterized the germline mutation landscape of DDRs in the largest oriental cohort of pancreatic cancer to date, and first discovered two novel germline mutations in pancreatic cancer. Most importantly, nearly 10% of PDAC patients in this study were found to harbor germline DDR mutations, which may benefit more patients with an effective therapeutic synergy for PARP and PD-1 inhibitors in clinical practice. Citation Format: Shiwei Guo, Lisha Jiang, Xiaohan Shi, Suizhi Gao, Bo Li, Ling Lin, Jun Yu, Gang Jin. Germline mutation landscape of DNA damage repair genes in Oriental pancreatic cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3540.

A patient-derived xenograft (PDX) approach, which relies on direct transplantation of tumor specimens into an immunocompromised animal, is a commonly used method for investigating tumor therapy predictions in vivo. This study evaluated influencing factors, including clinical, oncological, and genetic variables, for a pancreatic PDX model in mice. Tumor specimens were obtained from 121 patients with pancreatic ductal adenocarcinoma who underwent surgical resection at the Changhai Pancreatic Surgery Medical Center (Shanghai, China) between April 2016 and February 2017. Pancreatic cancer (PC) samples 3.5 cm in size was independently associated with xenograft formation rate. In addition, several enriched mutated genes within the VEGF pathway and higher microvessel density were found in the positive group (with xenograft) compared with the negative group (without xenograft). We concluded that tumor size and mutated VEGF pathway in PC are important factors affecting PDX model construction with NSG mice.-Guo, S., Gao, S., Liu, R., Shen, J., Shi, X., Bai, S., Wang, H., Zheng, K., Shao, Z., Liang, C., Peng, S., Jin, G. Oncological and genetic factors impacting PDX model construction with NSG mice in pancreatic cancer.

Purpose: Pancreatic ductal adenocarcinoma (PDAC) is of high mortality with a shortage of effective non-invasive biomarkers in the diagnosis and prognosis. Without a proper method to identify reasonable target molecules and their references for normalization, robust and accurate blood miRNA biomarkers have not been reported. We aim to explore the exosomal miRNAs as biomarkers for the diagnosis and prognosis of PDAC with sufficient biological insights and robustness. Materials and Methods: miRNA-seq was performed on miRNAs extracted from blood exosomes. 16 non-metastatic PDAC, 11 metastatic PDAC and 15 pancreatitis patients were enrolled in 2017 as the training set. Another 18 non-metastatic PDAC, 12 metastatic PDAC and 18 pancreatitis patients were enrolled in 2018 as the testing set. Bayesian network was built on the levels of miRNAs to identify candidate biomarkers with biological insights. The area under the curve (AUC) of receiver operating characteristic (ROC) was used to measure the accuracy of each pair of miRNAs. Results: The exosomal miRNA from the plasma of these patients with PDAC or pancreatitis has been successfully extracted and sequenced. The Bayesian network consisted of 337 nodes and 713 edges. The quotient of miR-95-3p (a “consequence” of “cancer”) over miR-26-5p (a “cause” of “pancreatitis”) performed 81.5% sensitivity and 93.3% specificity in the training cohort, and 86.7% sensitivity and 100% specificity in the testing cohort respectively. Furthermore, considering either high serum level of CA19-9 or the quotient of miR-95-3p/miR-26-5p as PDAC, the sensitivity increased to 96.5%, and the specificity was maintained at 96.9%. In addition, miR-335-5p level in blood exosome could predict metastasis with a mean accuracy of 77.2%, and showed strong relation with overall survival after surgeries. Conclusions: MiRNAs biomarkers from blood exosomes in differential diagnostics and prognosis are identified and rationale by Bayesian network. Integration of biomarkers of various molecular types could enhance the diagnostic accuracy beyond single molecular types. Blood exosomal miRNAs could be applied to monitor the development of PDAC. Citation Format: Shiwei Guo, Huan Wang, Hao Qin, Dadong Zhang, Zhuo Shao, Yanan Zhang, Bin Song, Xiaoya Xu, Jing Shen, Zishuo Chen, Xiaohan Shi, Suizhi Gao, Yaqi Pan, Fugen Li, Gang Jin. Identifying blood exosomal miRNAs as biomarkers in the diagnosis and prognosis of pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1363.