REDOX SIGNALLING IN THE PANCREAS IN HEALTH AND DISEASE.

This review addresses oxidative stress and redox signaling in the pancreas under physiological conditions as well as in acute pancreatitis, chronic pancreatitis, pancreatic cancer, and diabetes. Physiological redox homeodynamics is maintained mainly by NRF2/KEAP1, NF-κB, protein tyrosine phosphatases, peroxisome proliferator-activated receptor-γ co-activator 1α (PGC1α), and normal autophagy. Depletion of reduced glutathione in the pancreas is a hallmark of acute pancreatitis and is initially accompanied by disulfide stress, which is characterized by protein cysteinylation without increased glutathione oxidation. A cross-talk between oxidative stress, MAPKs, and NF-κB amplifies the inflammatory cascade, acting PP2A and PGC1α as key redox regulatory nodes. In acute pancreatitis, nitration of cystathionine-ß synthase causes blockade of the trans-sulfuration pathway leading to increased homocysteine levels, whereas p53 triggers necroptosis in the pancreas through downregulation of sulfiredoxin, PGC1α, and peroxiredoxin 3. Chronic pancreatitis exhibits oxidative distress mediated by NADPH oxidase 1 and/or CYP2E1, which promotes cell death, fibrosis, and inflammation. Oxidative stress cooperates with mutant KRAS to initiate and promote pancreatic adenocarcinoma. Mutant KRAS increases mitochondrial ROS, which trigger acinar-to-ductal metaplasia and progression to PanIN. ROS are maintained at sufficient level to promote cell proliferation, whilst avoiding cell death or senescence through formation of NADPH and GSH, and activation of NRF-2, HIF-1/2α, and CREB. Redox signalling also plays a fundamental role in differentiation, proliferation, and insulin secretion of ß-cells. However, ROS overproduction promotes ß-cell dysfunction and apoptosis in type 1 and type 2 diabetes.

Preoperative hepatic artery embolization before distal pancreatectomy plus celiac axis resection does not improve surgical results: A Spanish multicentre study.

BACKGROUND: Distal pancreatectomy with celiac axis resection (DP-CAR) is a surgical procedure with high morbidity and mortality performed in patients with locally advanced pancreatic cancer. Preoperative embolization of hepatic artery (PHAE) has been postulated as a technical option to increase resection rate. OBJECTIVE: comparison of morbidity and mortality at 90 days, operative time, hospital stay and survival between patients that performed DP-CAR with and without PHAE. METHODS: Observational retrospective multicentre study. INCLUSION CRITERIA: patient operated in Spanish centers with DP-CAR for pancreatic cancer from April 2004 until 23 June 2018. Preoperative (PHAE, neodjuvant treatment), intraoperative (operative time and blood loss) and postoperative data (morbidity, hospital stay, R0 and survival) were studied. Complications were measured with Clavien classification at 90 days. Specific pancreatic complications were measured using ISGPS classifications. Data were analyzed using R version 3.1.3 (http://www.r-project.org). Level of significance was set at 0.05. RESULTS: 41 patients were studied. 26 patients were not embolized (NO-PHAE group) and 15 patients received PHAE. Preoperative BMI and percentage of neoadjuvant chemotherapy were the only preoperative variables different between both groups. The operative time in the PHAE group was shorter (343 min) than in the non-PHAE group (411 min) (p < 0.06). Major morbidity (Clavien > IIIa) and mortality at 90 days were higher in the PHAE group than in the non-PHAE group (60% vs 23% and 26.6% vs 11.6% respectively) (p < 0.004). No statistical difference in overall survival was observed between both groups (p = 0.14). CONCLUSION: In our study PHAE is not related with less postoperative morbidity. Even more, major morbidity (Clavien III-IV) and mortality was higher in PHAE group.

Surgical treatment of an intraductal papillary mucinous neoplasm of the biliary tract diagnosed by SpyGlass®.

We present the case of a 76-year-old male with a history of acute cholecystitis who underwent a scheduled laparoscopic cholecystectomy. Chronic cholecystitis with a thickened cystic duct was observed intraoperatively. The anatomic pathology report found high-grade dysplasia that affected the distal edge of the cystic duct. In view of these findings, an endoscopic retrograde cholangiopancreatography (ERCP) was performed with SpyGlass® and an excrescent lesion suggestive of malignancy adjacent to the cystic-common bile duct junction was observed. A resection of the extrahepatic bile duct was performed with lymphadenectomy of the hepatic hilum and hepaticojejunostomy in a subsequent procedure. The definitive pathology report confirmed pancreaticobiliary intraductal papillary mucinous neoplasia with high-grade dysplasia and free margins.

Impact of type and severity of postoperative complications on long-term outcomes after colorectal liver metastases resection.

BACKGROUND AND OBJECTIVES: Postoperative complications (POCs) after hepatic resection for colorectal liver metastases (CRLM) adversely affect long-term survival. The aim of this study was to analyze the effect of POC etiology and severity on overall survival (OS) and disease-free survival (DFS). METHODS: A retrospective study of 254 consecutive hepatectomies for CRLM was performed. Univariate and multivariate analyses were performed to determine the effects of demographic, tumor-related and perioperative variables on OS and DFS. A 1:1 propensity score matching (PSM) was then used to compare patients with different POC etiology: infective (Inf-POC), noninfective (Non-inf POC), and no-complications (No-POC). RESULTS: Inf-POC, Non-inf POC, and No-POC patients represented 18.8%, 19.2%, and 62% of the sample, respectively. In univariate and multivariate analyses infectious POC were independent risk factors for decreased OS and DFS. After PSM, Inf-POC group presented decreased OS and DFS when compared with Non-inf POC (5-year OS 31.8% vs 51.6%; P = .05 and 5-year DFS 13.6% vs 31.9%; P = .04) and with No-POC (5-year OS 29.4% vs 58.7%; P = .03 and 5-year DFS 11.8% vs 39.7%; P = .03). There were no differences between Non-inf POC and No-POC patients. POC severity calculated using the Comprehensive Complications Index did not influence OS and DFS before and after PSM. CONCLUSION: The negative oncological impact of POCs after CRLM resection is determined by infective etiology not by severity.

Impact of Postoperative Complications on Survival and Recurrence After Resection of Colorectal Liver Metastases: Systematic Review and Meta-analysis.

OBJECTIVE: To study the effect of postoperative complications (POC) on overall survival (OS) and disease-free survival (DFS) after surgical resection of colorectal liver metastases (CRLM). SUMMARY BACKGROUND DATA: Morbidity rates after liver resection can reach 45%. The negative impact of POC on oncologic outcomes has been reported in various types of cancer, especially colorectal. However, data on the consequences of POC after CRLM resection on long-term survival are scarce. METHODS: Eligible studies examining the association between POC after CRLM resection and OS/DFS were sought using the PubMed and Web of Science databases. A random-effects model was used to calculate pooled effect estimate for OS and DFS hazard ratios (HR), estimating between-study variance with restricted maximum likelihood estimator with Hartung-Knapp adjustment. Subgroup analysis was used to control the effect of POC on OS and DFS for: 1) Method used to define postoperative complications, 2) Exclusion of early postoperative death from survival analysis, 3) Method of data extraction used, and 4) Tumor and treatment characteristics. RESULTS: Forty-one studies were deemed eligible, including 12,817 patients. POC patients had a significant risk of reduced OS compared with no POC group (HR 1.43 [95% CI: 1.3, 1.57], P < 0.0001). POC had also a negative impact on DFS. The HR for reduced DFS was 1.38 [95% CI 1.27, 1.49], P < 0.0001. The negative impact of POC on survival and recurrence was confirmed in subgroup analysis. CONCLUSIONS: Our findings evidence the negative impact of POC on survival and recurrence after CRLM resection.

Does the Artery-first Approach Improve the Rate of R0 Resection in Pancreatoduodenectomy?: A Multicenter, Randomized, Controlled Trial.

OBJECTIVE: To compare the rates of R0 resection in pancreatoduodenectomy (PD) for pancreatic and periampullary malignant tumors by means of standard (ST-PD) versus artery-first approach (AFA-PD). BACKGROUND: Standardized histological examination of PD specimens has shown that most pancreatic resections thought to be R0 resections are R1. "Artery-first approach" is a surgical technique characterized by meticulous dissection of arterial planes and clearing of retropancreatic tissue in an attempt to achieve a higher rate of R0. To date, studies comparing AFA-PD versus ST-PD are retrospective cohort or case-control studies. METHODS: A multicenter, randomized, controlled trial was conducted in 10 University Hospitals (NCT02803814, ClinicalTrials.gov). Eligible patients were those who presented with pancreatic head adenocarcinoma and periampullary tumors (ampulloma, distal cholangiocarcinoma, duodenal adenocarcinoma). Assignment to each group (ST-PD or AFA-PD) was randomized by blocks and stratified by centers. The primary end-point was the rate of tumor-free resection margins (R0); secondary end-points were postoperative complications and mortality. RESULTS: One hundred seventy-nine patients were assessed for eligibility and 176 randomized. After exclusions, the final analysis included 75 ST-PD and 78 AFA-PD. R0 resection rates were 77.3% (95% CI: 68.4-87.4) with ST-PD and 67.9% (95% CI: 58.3-79.1) with AFA-PD, P=0.194. There were no significant differences in postoperative complication rates, overall 73.3% versus 67.9%, and perioperative mortality 4% versus 6.4%. CONCLUSIONS: Despite theoretical oncological advantages associated with AFA-PD and evidence coming from low-level studies, this multicenter, randomized, controlled trial has found no difference neither in R0 resection rates nor in postoperative complications in patients undergoing ST-PD versus AFA-PD for pancreatic head adenocarcinoma and other periampullary tumors.

Role of obesity in the release of extracellular nucleosomes in acute pancreatitis: a clinical and experimental study.

BACKGROUND/OBJECTIVES: A high body mass index increases the risk of severe pancreatitis and associated mortality. Our aims were: (1) To determine whether obesity affects the release of extracellular nucleosomes in patients with pancreatitis; (2) To determine whether pancreatic ascites confers lipotoxicity and triggers the release of extracellular nucleosomes in lean and obese rats. METHODS: DNA and nucleosomes were determined in plasma from patients with mild or moderately severe acute pancreatitis either with normal or high body mass index (BMI). Lipids from pancreatic ascites from lean and obese rats were analyzed and the associated toxicity measured in vitro in RAW 264.7 macrophages. The inflammatory response, extracellular DNA and nucleosomes were determined in lean or obese rats with pancreatitis after peritoneal lavage. RESULTS: Nucleosome levels in plasma from obese patients with mild pancreatitis were higher than in normal BMI patients; these levels markedly increased in obese patients with moderately severe pancreatitis vs. those with normal BMI. Ascites from obese rats exhibited high levels of palmitic, oleic, stearic, and arachidonic acids. Necrosis and histone 4 citrullination-marker of extracellular traps-increased in macrophages incubated with ascites from obese rats but not with ascites from lean rats. Peritoneal lavage abrogated the increase in DNA and nucleosomes in plasma from lean or obese rats with pancreatitis. It prevented fat necrosis and induction of HIF-related genes in lung. CONCLUSIONS: Extracellular nucleosomes are intensely released in obese patients with acute pancreatitis. Pancreatitis-associated ascitic fluid triggers the release of extracellular nucleosomes in rats with severe pancreatitis.

The role of endoscopic retrograde cholangiopancreatography in the management of iatrogenic bile duct injury after cholecystectomy.

INTRODUCTION: iatrogenic bile duct injury (IBDI) is a complication with a high morbidity after cholecystectomy. In recent years, endoscopy has acquired a fundamental role in the management of this pathology. METHODS: a retrospective study of IBDI after open cholecystectomy (OC) or laparoscopic cholecystectomy (LC) of patients treated in our center between 1993 and 2017 was performed. Clinical characteristics, type of injury according to the Strasberg-Bismuth classification, diagnosis, repair techniques and follow-up were analyzed. RESULTS: 46 patients were studied and IBDI incidence was 0.48%, 0.61% for LC and 0.24% for OC. A diagnosis was made intraoperatively in 12 cases (26%) and by endoscopic retrograde cholangiopancreatography (ERCP) in 10 (21.7%) cases. The most common IBDI patient characteristics were acute cholecystitis (20/46, 43.5%), previous admission due to biliary pathology (16/46, 43.2%) and ERCP prior to cholecystectomy (7/46, 18.9%). The most frequent types of IBDI were D (17/46, 36.9%) and A (15/46, 32.6%). The most commonly used treatment was primary suture (13/46, 28.3%) followed by ERCP (11/46, 23.9%) with sphincterotomy and/or stents. In addition, ERCP was performed during the immediate postoperative period in 6 (13%) patients with a surgical IBDI repair in order to resolve immediate complications. CONCLUSION: ERCP is useful in the management of IBDI that is not diagnosed intraoperatively. This procedure facilitates the localization of the injured area of the bile duct, therapeutic maneuvers and successful outcomes in postoperative complications.

Is Percutaneous Transhepatic Biliary Drainage Better than Endoscopic Drainage in the Management of Jaundiced Patients Awaiting Pancreaticoduodenectomy? A Systematic Review and Meta-analysis.

PURPOSE: To compare postoperative complications in patients who underwent pancreatoduodenectomy after either endoscopic or percutaneous biliary drain (BD). MATERIAL AND METHODS: Data from studies comparing the rate of postoperative complications in patients who underwent endoscopic BD or percutaneous BD before pancreatoduodenectomy were extracted independently by 2 investigators. The primary outcome compared in the meta-analysis was the risk of postoperative complications. Secondary outcomes were the risks of procedure-related complications, postoperative mortality, postoperative pancreatic fistula, severe complications, and wound infection. For dichotomous variables, the odds ratio (OR) with 95% confidence interval (CI) was calculated. RESULTS: Thirteen studies, including 2334 patients (501 in the percutaneous BD group and 1833 in the endoscopic group), met the inclusion criteria. Postoperative and procedure-related complication rates were significantly lower in the percutaneous BD group (OR = .7, 95% CI = .52-.94, P = .02 and OR = .44, 95% CI = .23-.84, P = .01, respectively). No significant differences were observed when severe postoperative complications, postoperative mortality, postoperative pancreatic fistula, and wound infection rates were compared. CONCLUSIONS: In patients awaiting pancreatoduodenectomy, preoperative percutaneous BD is associated with fewer procedure-related or postoperative complications than endoscopic drain.

Evidence-based Guidelines for the Management of Exocrine Pancreatic Insufficiency After Pancreatic Surgery.

OBJECTIVE: To provide evidence-based recommendations for the management of exocrine pancreatic insufficiency (EPI) after pancreatic surgery. BACKGROUND: EPI is a common complication after pancreatic surgery but there is certain confusion about its frequency, optimal methods of diagnosis, and when and how to treat these patients. METHODS: Eighteen multidisciplinary reviewers performed a systematic review on 10 predefined questions following the GRADE methodology. Six external expert referees reviewed the retrieved information. Members from Spanish Association of Pancreatology were invited to suggest modifications and voted for the quantification of agreement. RESULTS: These guidelines analyze the definition of EPI after pancreatic surgery, (one question), its frequency after specific techniques and underlying disease (four questions), its clinical consequences (one question), diagnosis (one question), when and how to treat postsurgical EPI (two questions) and its impact on the quality of life (one question). Eleven statements answering those 10 questions were provided: one (9.1%) was rated as a strong recommendation according to GRADE, three (27.3%) as moderate and seven (63.6%) as weak. All statements had strong agreement. CONCLUSIONS: EPI is a frequent but under-recognized complication of pancreatic surgery. These guidelines provide evidence-based recommendations for the definition, diagnosis, and management of EPI after pancreatic surgery.

Outcome quality standards in pancreatic oncologic surgery.

PURPOSE: To identify quality indicators and establish acceptable quality limits (AQLs) in pancreatic oncologic surgery using a formal statistical methodology. METHODS: Indicators have been identified through systematic literature reviews and guidelines for pancreatic surgery. AQLs were determined for each indicator with confidence intervals of 99.8 and 95 % above and below the weighted average by sample size from the different series examined. RESULTS: Several indicators have been identified with the following results as AQLs: resectability rate >59 %; morbidity, mortality, and pancreatic fistula rate in pancreaticoduodenectomy <55, <5, and <16 %, respectively; morbidity, mortality, and fistula rate in distal pancreatectomy <53, <4, and <31 %, respectively; number of lymph nodes retrieved >15; R1 resection <46 %; survival at 1, 3, and 5 years >54, >19, and >8 %, respectively. CONCLUSIONS: A series of different indicators for quality surgical care outcome in pancreatic cancer, as well as their limits, have been determined according to a standard methodology.

[Multicentre study on hepatic adenomas]. / Estudio multicéntrico sobre adenomas hepáticos.

INTRODUCTION: Hepatic adenomas (HA) are benign tumours which can present serious complications, and as such, in the past all were resected. It has now been shown that those smaller than 3 cm not expressing ß-catenin only result in complications in exceptional cases and therefore the therapeutic strategy has been changed. MATERIAL AND METHOD: Retrospective study in 14 HPB units. INCLUSION CRITERIA: patients with resected and histologically confirmed HA. STUDY PERIOD: 1995-2011. RESULTS: 81 patients underwent surgery. Age: 39.5 years (range: 14-75). Sex: female (75%). Consumption of oestrogen in women: 33%. Size: 8.8 cm (range, 1-20 cm). Only 6 HA (7.4%) were smaller than 3 cm. The HA median was 1 (range: 1-12). Nine patients had adenomatosis (>10HA). A total of 51% of patients displayed symptoms, the most frequent (77%) being abdominal pain. Eight patients (10%) began with acute abdomen due to rupture and/or haemorrhage. A total of 67% of the preoperative diagnoses were correct. Surgery was scheduled for 90% of patients. The techniques employed were: major hepatectomy (22%), minor hepatectomy (77%) and one liver transplantation. A total of 20% were performed laparoscopically. The morbidity rate was 28%. There were no cases of mortality. Three patients had malignisation (3.7%). The follow-up period was 43 months (range 1-192). Two recurrences were detected and resected. DISCUSSION: Patients with resected HA are normally women with large lesions and oestrogen consumption was lower than expected. Its correct preoperative diagnosis is acceptable (70%). The major hepatectomy rate is 25% and the laparoscopy rate is 20%. There was a low morbidity rate and no mortality.

Prognostic implications of the standardized study of resection margins in pancreatic cancers.

INTRODUCTION: Involvement of surgical resection margins is a fundamental prognostic factor in pancreatic oncological surgery. However, there is a lack of standardized histopathology definition. The aims of this study are to investigate the real rate of R1 resections when surgical specimens are evaluated according to a standardized protocol and to study its survival implications. PATIENTS Y METHODS: One hundred consecutive surgically resected patients with pancreatic ductal adenocarcinoma were included in the study. They were further divided in 2 groups: pre-protocol, evaluated before the introduction of the standardized protocol and post-protocol, analyzed with the standardized protocol. RESULTS: R0 resection rate in the pre-protocol group was 78%, falling to 47% after the introduction of the standardized protocol (p=0,003). The posterior retroperitoneal margin was the most frequently involved margin. In cases with tumors located at the pancreatic head and analyzed according to the standardized protocol R1 involvement negatively affected survival. Median survival in the R0 group was 22 months versus 16 in those with the margin involved (HR: 2.044; IC 95% 1,00-4,16; P=.043). CONCLUSIONS: Standardized evaluation of the retroperitoneal margins in pancreatic cancer increases the rate of R1 patients. In cases with pancreatic cancer located at the pancreatic head involvement of posterior retroperitoneal margin significantly decreases survival.

Solid pseudopapillary neoplasms of the pancreas: Multicenter Vasepa study.

INTRODUCTION: Solid pseudopapillary tumors (SPT) of the pancreas are rare exocrine neoplasms of the pancreas. Correct preoperative diagnosis is not always feasible. The treatment of choice is surgical excision. These tumors have a good prognosis with a high disease-free survival rate. OBJECTIVE: To describe the clinicopathological and radiological characteristics as well as short- and long-term follow-up results of patients who have undergone SPT resection. METHODS: Multicenter retrospective observational study in patients with SPT who had undergone surgery from January 2000-January 2022. We have studied preoperative, intraoperative, and postoperative variables as well as the follow-up results (mean 28 months). RESULTS: 20 patients with histological diagnosis of SPT in the surgical specimen were included. 90% were women; mean age was 33.5 years (13-67); 50% were asymptomatic. CT was the most used diagnostic test (90%). The most frequent location was body-tail (60%). Preoperative biopsy was performed in 13 patients (65%), which was correct in 8 patients. Surgeries performed: 7 distal pancreatectomies, 6 pancreaticoduodenectomies, 4 central pancreatectomies, 2 enucleations, and 1 total pancreatectomy. The R0 rate was 95%. Four patients presented major postoperative complications (Clavien-Dindo > II). Mean tumor size was 81 mm. Only one patient received adjuvant chemotherapy. With a mean follow-up of 28 months, 5-year disease-free survival was 95%. CONCLUSION: SPT are large, usually located in the body-tail of the pancreas, and more frequent in women. The R0 rate obtained in our series is very high (95%). The oncological results are excellent.

Textbook outcome in distal pancreatectomy: A multicenter study.

BACKGROUND: Textbook outcome is an interesting quality metrics tool. Information on textbook outcomes in distal pancreatectomy is very scarce. In this study we determined textbook outcome in a distal pancreatectomy multicenter database and propose a specific definition of textbook outcome-distal pancreatectomy that includes pancreatic fistula. METHODS: Retrospective multicenter observational study of distal pancreatectomy performed at 8 hepatopancreatobiliary surgery units from January 1, 2008, to December 31, 2018. The inclusion criteria were any scheduled distal pancreatectomy performed for any diagnosis and age > 18 years. Specific textbook outcome-distal pancreatectomy was defined as hospital stay P < 75, no Clavien-Dindo complications (≥ III), no hospital mortality, and no readmission recorded at 90 days, and the absence of pancreatic fistula (B/C). RESULTS: Of the 450 patients included, 262 (58.2%) obtained textbook outcomes. Prolonged stay was the parameter most frequently associated with failure to achieve textbook outcomes. The textbook outcome group presented the following results. Preoperative: lower American Society of Anesthesiologists score < III, a lower percentage of smokers, and less frequent tumor invasion of neighboring organs or vascular invasion; operative: major laparoscopic approach, and less resection of neighboring organs and less operative transfusion; postoperative: lower percentage of delayed gastric emptying and pancreatic fistula B/C, and diagnosis other an adenocarcinoma. In the multivariate study, the American Society of Anesthesiologists score > II, resection of neighboring organs, B/C pancreatic fistula, and delayed gastric emptying were associated with failure to achieve textbook outcomes. CONCLUSION: The textbook outcome rate in our 450 pancreaticoduodenectomies was 58.2%. In the multivariate analysis, the causes of failure to achieve textbook outcomes were American Society of Anesthesiologists score > II, resection of neighboring organs, pancreatic fistula B/C, and delayed gastric emptying. We believe that pancreatic fistula should be added to the specific definition of textbook outcome-distal pancreatectomy because it is the most frequent complication of this procedure.

Short- and long-term outcomes after distal pancreatectomy with radiologic infiltration of splenic vessels for pancreatic ductal adenocarcinoma.

BACKGROUND: The effect of radiologic splenic vessels involvement (RSVI) on the survival of patients with pancreatic adenocarcinoma (PAC) located in the body and tail of the pancreas is controversial, and its influence on postoperative morbidity after distal pancreatectomy (DP) is unknown. This study aimed to determine the influence of RSVI on postoperative complications, overall survival (OS), and disease-free survival (DFS) in patients undergoing DP for PAC. METHODS: A multicenter retrospective study of DP was conducted at 7 hepatopancreatobiliary units between January 2008 and December 2018. Patients were classified according to the presence of RSVI. A Clavien-Dindo grade of >II was considered to represent a major complication. RESULTS: A total of 95 patients were included in the analysis. Moreover, 47 patients had vascular infiltration: 4 had arterial involvement, 10 had venous involvement, and 33 had both arterial and venous involvements. The rates of major complications were 20.8% in patients without RSVI, 40.0% in those with venous RSVI, 25.0% in those with arterial RSVI, and 30.3% in those with both arterial and venous RSVIs (P = .024). The DFS rates at 3 years were 56% in the group without RSVI, 50% in the group with arterial RSVI, and 16% in the group with both arterial and venous RSVIs (P = .003). The OS rates at 3 years were 66% in the group without RSVI, 50% in the group with arterial RSVI, and 29% in the group with both arterial and venous RSVIs (P < .0001). CONCLUSION: RSVI increased the major complication rates after DP and reduced the OS and DFS. Therefore, it may be a useful prognostic marker in patients with PAC scheduled to undergo DP and may help to select patients likely to benefit from neoadjuvant treatment.

ctDNA whole exome sequencing in pancreatic ductal adenocarcinoma unveils organ-dependent metastatic mechanisms and identifies actionable alterations in fast progressing patients.

Understanding progression mechanisms and developing new targeted therapies is imperative in pancreatic ductal adenocarcinoma (PDAC). In this study, 80 metastatic PDAC patients were prospectively recruited and divided into discovery (n=37) and validation (n=43) cohorts. Tumor and plasma samples taken at diagnosis were pair analyzed using whole exome sequencing (WES) in patients belonging to the discovery cohort alone. The variant allele frequency (VAF) of KRAS mutations was measured by ddPCR in plasma at baseline and response assessment in all patients. Plasma WES identified at least one pathogenic variant across the cohort, uncovering oncogenic mechanisms, DNA repair, microsatellite instability, and alterations in the TGFb pathway. Interestingly, actionable mutations were mostly found in plasma rather than tissue. Patients with shorter survival showed enrichment in cellular organization regulatory pathways. Through WES we could identify a specific molecular profile of patients with liver metastasis, which exhibited exclusive mutations in genes related to the adaptive immune response pathway, highlighting the importance of the immune system in liver metastasis development. Moreover, KRAS mutations in plasma (both at diagnosis and persistent at follow-up) correlated with shorter progression free survival (PFS). Patients presenting a reduction of over 84.75 % in KRAS VAF at response assessment had similar PFS to KRAS-negative patients. Overall, plasma WES reveals molecular profiles indicative of rapid progression, potentially actionable targets, and associations between adaptive immune response pathway alterations and liver tropism.