Analysis of single nuclear chromatin accessibility reveals unique myeloid populations in human pancreatic ductal adenocarcinoma.

BACKGROUND: A better understanding of the pancreatic ductal adenocarcinoma (PDAC) immune microenvironment is critical to developing new treatments and improving outcomes. Myeloid cells are of particular importance for PDAC progression; however, the presence of heterogenous subsets with different ontogeny and impact, along with some fluidity between them, (infiltrating monocytes vs. tissue-resident macrophages; M1 vs. M2) makes characterisation of myeloid populations challenging. Recent advances in single cell sequencing technology provide tools for characterisation of immune cell infiltrates, and open chromatin provides source and function data for myeloid cells to assist in more comprehensive characterisation. Thus, we explore single nuclear assay for transposase accessible chromatin (ATAC) sequencing (snATAC-Seq), a method to analyse open gene promoters and transcription factor binding, as an important means for discerning the myeloid composition in human PDAC tumours. METHODS: Frozen pancreatic tissues (benign or PDAC) were prepared for snATAC-Seq using 10× Chromium technology. Signac was used for preliminary analysis, clustering and differentially accessible chromatin region identification. The genes annotated in promoter regions were used for Gene Ontology (GO) enrichment and cell type annotation. Gene signatures were used for survival analysis with The Cancer Genome Atlas (TCGA)-pancreatic adenocarcinoma (PAAD) dataset. RESULTS: Myeloid cell transcription factor activities were higher in tumour than benign pancreatic samples, enabling us to further stratify tumour myeloid populations. Subcluster analysis revealed eight distinct myeloid populations. GO enrichment demonstrated unique functions for myeloid populations, including interleukin-1b signalling (recruited monocytes) and intracellular protein transport (dendritic cells). The identified gene signature for dendritic cells influenced survival (hazard ratio = .63, p = .03) in the TCGA-PAAD dataset, which was unique to PDAC. CONCLUSIONS: These data suggest snATAC-Seq as a method for analysis of frozen human pancreatic tissues to distinguish myeloid populations. An improved understanding of myeloid cell heterogeneity and function is important for developing new treatment targets in PDAC.

Group A streptococcal collagen-like protein 1 restricts tumor growth in murine pancreatic adenocarcinoma and inhibits cancer-promoting neutrophil extracellular traps.

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer associated with an immunosuppressive environment. Neutrophil extracellular traps (NETs) were initially described in the context of infection but have more recently been implicated in contributing to the tolerogenic immune response in PDAC. Thus, NETs are an attractive target for new therapeutic strategies. Group A Streptococcus (GAS) has developed defensive strategies to inhibit NETs. Methods: In the present work, we propose utilizing intra-tumoral GAS injection to stimulate anti-tumor activity by inhibiting cancer-promoting NETs. Mice harboring Panc02 or KPC subcutaneous tumors injected with three different M-type GAS strains. Tumors and spleens were harvested at the endpoint of the experiments to assess bacterial colonization and systemic spread, while sera were analyzed for humoral responses toward the streptococcal antigens, especially the M1 and Scl1 proteins. Role of the streptococcal collagen-like protein 1 (Scl1) in anti-PDAC activity was assessed in vivo after intratumoral injection with M1 GAS wild-type, an isogenic mutant strain devoid of Scl1, or a complemented mutant strain with restored scl1 expression. In addition, recombinant Scl1 proteins were tested for NET inhibition using in vitro and ex vivo assays assessing NET production and myeloperoxidase activity. Results: Injection of three different M-type GAS strains reduced subcutaneous pancreatic tumor volume compared to control in two different murine PDAC models. Limitation of tumor growth was dependent on Scl1, as isogenic mutant strain devoid of Scl1 did not reduce tumor size. We further show that Scl1 plays a role in localizing GAS to the tumor site, thereby limiting the systemic spread of bacteria and off-target effects. While mice did elicit a humoral immune response to GAS antigens, tested sera were weakly immunogenic toward Scl1 antigen following intra-tumoral treatment with Scl1-expressing GAS. M1 GAS inhibited NET formation when co-cultured with neutrophils while Scl1-devoid mutant strain did not. Recombinant Scl1 protein inhibited NETs ex vivo in a dose-dependent manner by suppressing myeloperoxidase activity. Discussion: Altogether, we demonstrate that intra-tumoral GAS injections reduce PDAC growth, which is facilitated by Scl1, in part through inhibition of cancer promoting NETs. This work offers a novel strategy by which NETs can be targeted through Scl1 protein and potentiates its use as a cancer therapeutic.

Targeting myeloperoxidase limits myeloid cell immunosuppression enhancing immune checkpoint therapy for pancreatic cancer.

Pancreatic ductal adenocarcinoma is a devastating disease characterized by an extreme resistance to current therapies, including immune checkpoint therapy. The limited success of immunotherapies can be attributed to a highly immunosuppressive pancreatic cancer microenvironment characterized by an extensive infiltration of immune suppressing myeloid cells. While there are several pathways through which myeloid cells contribute to immunosuppression, one important mechanism is the increased production of reactive oxygen species. Here, we evaluated the contribution of myeloperoxidase, a myeloid-lineage restricted enzyme and primary source of reactive oxygen species, to regulate immune checkpoint therapy response in preclinical pancreatic cancer models. We compared treatment outcome, immune composition and characterized myeloid cells using wild-type, myeloperoxidase-deficient, and myeloperoxidase inhibitor treated wild-type mice using established subcutaneous pancreatic cancer models. Loss of host myeloperoxidase and pharmacological inhibition of myeloperoxidase in combination with immune checkpoint therapy significantly delayed tumor growth. The tumor microenvironment and systemic immune landscape demonstrated significant decreases in myeloid cells, exhausted T cells and T regulatory cell subsets when myeloperoxidase was deficient. Loss of myeloperoxidase in isolated myeloid cell subsets from tumor-bearing mice resulted in decreased reactive oxygen species production and T cell suppression. These data suggest that myeloperoxidase contributes to an immunosuppressive microenvironment and immune checkpoint therapy resistance where myeloperoxidase inhibitors have the potential to enhance immunotherapy response. Repurposing myeloperoxidase specific inhibitors may provide a promising therapeutic strategy to expand therapeutic options for pancreatic cancer patients to include immunotherapies.

Prophylactic Hyperthermic Intraperitoneal Chemotherapy for Patients at High Risk of Developing Gallbladder Cancer Peritoneal Metastases: Case Report and Rationale for a Prospective Clinical Trial.

Gallbladder cancer is a devastating disease with a 5-year survival of only 18%. The majority of gallbladder cancers are discovered incidentally in patients undergoing cholecystectomy. During non-oncologic laparoscopic cholecystectomy for gallbladder disease, gallbladder perforation occurs in 29% of cases and spillage of gallstones occurs in 9% of cases. Patients with gallbladder cancer frequently develop peritoneal recurrence, particularly after intra-operative bile spillage during cholecystectomy for incidental gallbladder cancer. The high likelihood of spillage and peritoneal seeding during cholecystectomy for incidental gallbladder cancer suggests the need for prophylactic strategies to prevent peritoneal carcinomatosis. Hyperthermic intraperitoneal chemotherapy (HIPEC) has efficacy in gallbladder cancer patients with macroscopic peritoneal disease undergoing cytoreductive surgery and has been associated with a survival advantage in a multi-institutional retrospective case series. However, the utilization of HIPEC with a prophylactic intent against the development of peritoneal disease following resection of gallbladder cancer has not yet been prospectively studied. Here, we review the literature surrounding gallbladder cancer and HIPEC, report an institutional experience utilizing prophylactic HIPEC, and discuss a recently proposed prospective clinical trial evaluating the efficacy of prophylactic HIPEC in the prevention of gallbladder peritoneal metastasis.

Group A Streptococcal Collagen-like Protein 1 Restricts Tumor Growth in Murine Pancreatic Adenocarcinoma and Inhibits Cancer-Promoting Neutrophil Extracellular Traps.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer associated with an immunosuppressive environment. Neutrophil extracellular traps (NETs) were initially described in the context of infection but have more recently been implicated in contributing to the tolerogenic immune response in PDAC. Thus, NETs are an attractive target for new therapeutic strategies. Group A Streptococcus (GAS) has developed defensive strategies to inhibit NETs. In the present work, we propose utilizing intra-tumoral GAS injection to stimulate anti-tumor activity by inhibiting cancer-promoting NETs. Injection of three different M-type GAS strains reduced subcutaneous pancreatic tumor volume compared to control in two different murine PDAC models. Limitation of tumor growth was dependent on streptococcal collagen-like protein 1 (Scl1), as isogenic mutant strain devoid of Scl1 did not reduce tumor size. We further show that Scl1 plays a role in localizing GAS to the tumor site, thereby limiting the systemic spread of bacteria and off-target effects. While mice did elicit a humoral immune response to GAS antigens, tested sera were negative toward Scl1 antigen following intra-tumoral treatment with Scl1-expressing GAS. M1 GAS inhibited NET formation when co-cultured with neutrophils while Scl1-devoid mutant strain did not. Recombinant Scl1 protein inhibited NETs ex vivo in a dose-dependent manner by suppressing myeloperoxidase activity. Altogether, we demonstrate that intra-tumoral GAS injections reduce PDAC growth, which is facilitated by Scl1, in part through inhibition of cancer promoting NETs. This work offers a novel strategy by which NETs can be targeted through Scl1 protein and potentiates its use as a cancer therapeutic.

Pancreatectomy Induces Cancer-Promoting Neutrophil Extracellular Traps.

BACKGROUND: Neutrophil extracellular traps (NETs) occur when neutrophil chromatin is decondensed and extruded into the extracellular space in a web-like structure. Originally described as an anti-microbial function, this process has been implicated in the pathogenesis of pancreatic disease. In addition, NETs are upregulated during physiologic wound-healing and coagulation. This study evaluated how the inflammatory response to pancreatic surgery influences NET formation. METHODS: For this study, 126 patients undergoing pancreatectomy gave consent before participation. Plasma was collected at several time points (preoperatively and through the postoperative outpatient visit). Plasma levels of NET markers, including cell-free DNA (cfDNA), citrullinated histone H3 (CitH3), interleukin (IL)-8, IL-6, and granulocyte colony-stimulating factor (G-CSF) were measured using enzyme-linked immunosorbent assay (ELISA). Patient clinical data were retrospectively collected from a prospectively maintained database. RESULTS: After pancreatic resection, NET markers (cfDNA and CitH3) were elevated, peaking on postoperative days 3 and 4. This increase in NETs was due to an inherent change in neutrophil biology. Postoperatively, NET-inducing cytokines (IL-8, IL-6, and G-CSF) were increased, peaking early in the postoperative course. The patients undergoing the robotic approach had a reduction in NETs during the postoperative period compared with those who underwent the open approach. The patients who experienced a pancreatic leak had an increase in NET markers during the postoperative period. CONCLUSIONS: Pancreatectomy induces cancer-promoting NET formation. The minimally invasive robotic approach may induce fewer NETs, although the current analysis was limited by selection bias. Pancreatic leak resulted in increased NETs. Further study into the potential for NET inhibition during the perioperative period is warranted.

Emerging applications of cancer bacteriotherapy towards treatment of pancreatic cancer.

Pancreatic cancer is a highly aggressive form of cancer with a five-year survival rate of only ten percent. Pancreatic ductal adenocarcinoma (PDAC) accounts for ninety percent of those cases. PDAC is associated with a dense stroma that confers resistance to current treatment modalities. Increasing resistance to cancer treatments poses a challenge and a need for alternative therapies. Bacterial mediated cancer therapies were proposed in the late 1800s by Dr. William Coley when he injected osteosarcoma patients with live streptococci or a fabrication of heat-killed Streptococcus pyogenes and Serratia marcescens known as Coley's toxin. Since then, several bacteria have gained recognition for possible roles in potentiating treatment response, enhancing anti-tumor immunity, and alleviating adverse effects to standard treatment options. This review highlights key bacterial mechanisms and structures that promote anti-tumor immunity, challenges and risks associated with bacterial mediated cancer therapies, and applications and opportunities for use in PDAC management.

Robotic modified Strong procedure for superior mesenteric artery syndrome.

Key Clinical Message: The robotic modified Strong procedure is a safe and effective approach for surgical management of superior mesenteric artery syndrome in properly selected patients. Abstract: Superior mesenteric artery syndrome is a rare syndrome of small bowel obstruction resulting from vascular compression of the duodenum. Here we present our modification of a robotic Strong procedure for the surgical management of SMA syndrome. This procedure is a safe and effective approach for management in properly selected patients.

A Combined DNA/RNA-based Next-Generation Sequencing Platform to Improve the Classification of Pancreatic Cysts and Early Detection of Pancreatic Cancer Arising From Pancreatic Cysts.

OBJECTIVE: We report the development and validation of a combined DNA/RNA next-generation sequencing (NGS) platform to improve the evaluation of pancreatic cysts. BACKGROUND AND AIMS: Despite a multidisciplinary approach, pancreatic cyst classification, such as a cystic precursor neoplasm, and the detection of high-grade dysplasia and early adenocarcinoma (advanced neoplasia) can be challenging. NGS of preoperative pancreatic cyst fluid improves the clinical evaluation of pancreatic cysts, but the recent identification of novel genomic alterations necessitates the creation of a comprehensive panel and the development of a genomic classifier to integrate the complex molecular results. METHODS: An updated and unique 74-gene DNA/RNA-targeted NGS panel (PancreaSeq Genomic Classifier) was created to evaluate 5 classes of genomic alterations to include gene mutations (e.g., KRAS, GNAS, etc.), gene fusions and gene expression. Further, CEA mRNA ( CEACAM5 ) was integrated into the assay using RT-qPCR. Separate multi-institutional cohorts for training (n=108) and validation (n=77) were tested, and diagnostic performance was compared to clinical, imaging, cytopathologic, and guideline data. RESULTS: Upon creation of a genomic classifier system, PancreaSeq GC yielded a 95% sensitivity and 100% specificity for a cystic precursor neoplasm, and the sensitivity and specificity for advanced neoplasia were 82% and 100%, respectively. Associated symptoms, cyst size, duct dilatation, a mural nodule, increasing cyst size, and malignant cytopathology had lower sensitivities (41-59%) and lower specificities (56-96%) for advanced neoplasia. This test also increased the sensitivity of current pancreatic cyst guidelines (IAP/Fukuoka and AGA) by >10% and maintained their inherent specificity. CONCLUSIONS: PancreaSeq GC was not only accurate in predicting pancreatic cyst type and advanced neoplasia but also improved the sensitivity of current pancreatic cyst guidelines.

Acute pancreatitis induces a transient hypercoagulable state in murine models.

BACKGROUND/OBJECTIVES: Although understudied, risk of venous thromboembolism (VTE) appears to be increased during acute pancreatitis (AP). We aimed to further characterize a hypercoagulable state associated with AP utilizing thromboelastography (TEG), a readily available, point of care test. METHODS: AP was induced in C57/Bl6 mice using l-arginine and caerulein. TEG was performed with citrated native samples. The maximum amplitude (MA) and coagulation index (CI), a composite marker of coagulability, were evaluated. Platelet aggregation was assessed using whole blood collagen-activated platelet impedance aggregometry. Circulating tissue factor (TF), the initiator of extrinsic coagulation, was measured with ELISA. A VTE model using IVC ligation followed by measurement of clot size and weight was evaluated. After IRB approval and consent, blood samples from patients hospitalized with a diagnosis of AP were evaluated by TEG. RESULTS: Mice with AP displayed a significant increase in MA and CI, consistent with hypercoagulability. Hypercoagulability peaked at 24 h after induction of pancreatitis, then returned to baseline by 72 h. AP resulted in significantly increased platelet aggregation and elevated circulating TF. Increased clot formation with AP was observed in an in vivo model of deep vein thrombosis. In a proof of concept, correlative study, over two thirds of patients with AP demonstrated an elevated MA and CI compared to the normal range, consistent with hypercoagulability. CONCLUSIONS: Murine acute pancreatitis results in a transient hypercoagulable state that can be assessed by TEG. Correlative evidence for hypercoagulability was also demonstrated in human pancreatitis. Further study to correlate coagulation measures to incidence of VTE in AP is warranted.

Chloroquine reduces neutrophil extracellular trap (NET) formation through inhibition of peptidyl arginine deiminase 4 (PAD4).

Neutrophil extracellular traps (NETs) occur when chromatin is decondensed and extruded from the cell, generating a web-like structure. NETs have been implicated in the pathogenesis of several sterile disease states and thus are a potential therapeutic target. Various pathways have been shown to induce NETs, including autophagy, with several key enzymes being activated like peptidyl arginine deiminase 4 (PAD4), an enzyme responsible for citrullination of histones, allowing for DNA unwinding and subsequent release from the cell. Pre-clinical studies have already demonstrated that chloroquine (CQ) and hydroxychloroquine (HCQ) are able to reduce NETs and slow disease progression. The exact mechanism as to how these drugs reduce NETs has yet to be elucidated. CQ and HCQ decrease NET formation from various NET activators, independent of their autophagy inhibitory function. CQ and HCQ were found to inhibit PAD4 exclusively, in a dose-dependent manner, confirmed with reduced CitH3+ NETs after CQ or HCQ treatment. Circulating CitH3 levels were reduced in pancreatic cancer patients after HCQ treatment. In silico screening of PAD4 protein structure identified a likely binding site interaction at Arg639 for CQ and Trp347, Ser468, and Glu580 for HCQ. SPR analysis confirmed the binding of HCQ and CQ with PAD4 with KD values of 54.1 µM (CQ) and 88.1 µM (HCQ). This data provide evidence of direct PAD4 inhibition as a mechanism for CQ/HCQ inhibition of NETs. We propose that these drugs likely reduce NET formation through multiple mechanisms; the previously established TLR9 and autophagy inhibitory mechanism and the novel PAD4 inhibitory mechanism.

Prospective, Multi-Institutional, Real-Time Next-Generation Sequencing of Pancreatic Cyst Fluid Reveals Diverse Genomic Alterations That Improve the Clinical Management of Pancreatic Cysts.

BACKGROUND & AIMS: Next-generation sequencing (NGS) of pancreatic cyst fluid is a useful adjunct in the assessment of patients with pancreatic cyst. However, previous studies have been retrospective or single institutional experiences. The aim of this study was to prospectively evaluate NGS on a multi-institutional cohort of patients with pancreatic cyst in real time. METHODS: The performance of a 22-gene NGS panel (PancreaSeq) was first retrospectively confirmed and then within a 2-year timeframe, PancreaSeq testing was prospectively used to evaluate endoscopic ultrasound-guided fine-needle aspiration pancreatic cyst fluid from 31 institutions. PancreaSeq results were correlated with endoscopic ultrasound findings, ancillary studies, current pancreatic cyst guidelines, follow-up, and expanded testing (Oncomine) of postoperative specimens. RESULTS: Among 1933 PCs prospectively tested, 1887 (98%) specimens from 1832 patients were satisfactory for PancreaSeq testing. Follow-up was available for 1216 (66%) patients (median, 23 months). Based on 251 (21%) patients with surgical pathology, mitogen-activated protein kinase/GNAS mutations had 90% sensitivity and 100% specificity for a mucinous cyst (positive predictive value [PPV], 100%; negative predictive value [NPV], 77%). On exclusion of low-level variants, the combination of mitogen-activated protein kinase/GNAS and TP53/SMAD4/CTNNB1/mammalian target of rapamycin alterations had 88% sensitivity and 98% specificity for advanced neoplasia (PPV, 97%; NPV, 93%). Inclusion of cytopathologic evaluation to PancreaSeq testing improved the sensitivity to 93% and maintained a high specificity of 95% (PPV, 92%; NPV, 95%). In comparison, other modalities and current pancreatic cyst guidelines, such as the American Gastroenterology Association and International Association of Pancreatology/Fukuoka guidelines, show inferior diagnostic performance. The sensitivities and specificities of VHL and MEN1/loss of heterozygosity alterations were 71% and 100% for serous cystadenomas (PPV, 100%; NPV, 98%), and 68% and 98% for pancreatic neuroendocrine tumors (PPV, 85%; NPV, 95%), respectively. On follow-up, serous cystadenomas with TP53/TERT mutations exhibited interval growth, whereas pancreatic neuroendocrine tumors with loss of heterozygosity of ≥3 genes tended to have distant metastasis. None of the 965 patients who did not undergo surgery developed malignancy. Postoperative Oncomine testing identified mucinous cysts with BRAF fusions and ERBB2 amplification, and advanced neoplasia with CDKN2A alterations. CONCLUSIONS: PancreaSeq was not only sensitive and specific for various pancreatic cyst types and advanced neoplasia arising from mucinous cysts, but also reveals the diversity of genomic alterations seen in pancreatic cysts and their clinical significance.

Biologic Functions of Hydroxychloroquine in Disease: From COVID-19 to Cancer.

Chloroquine (CQ) and Hydroxychloroquine (HCQ), initially utilized in the treatment of malaria, have now developed a long list of applications. Despite their clinical relevance, their mechanisms of action are not clearly defined. Major pathways by which these agents are proposed to function include alkalinization of lysosomes and endosomes, downregulation of C-X-C chemokine receptor type 4 (CXCR4) expression, high-mobility group box 1 protein (HMGB1) inhibition, alteration of intracellular calcium, and prevention of thrombus formation. However, there is conflicting data present in the literature. This is likely the result of the complex overlapping pathways between these mechanisms of action that have not previously been highlighted. In fact, prior research has focused on very specific portions of particular pathways without describing these in the context of the extensive CQ/HCQ literature. This review summarizes the detailed data regarding CQ/HCQ's mechanisms of action while also providing insight into the overarching themes. Furthermore, this review provides clinical context to the application of these diverse drugs including their role in malaria, autoimmune disorders, cardiovascular disease, thrombus formation, malignancies, and viral infections.

Molecular pathogenesis and emerging targets of gastric adenocarcinoma.

Gastric adenocarcinoma (GC) is a devastating disease and is the third leading cause of cancer deaths worldwide. This heterogeneous disease has several different classification systems that consider histological appearance and genomic alterations. Understanding the etiology of GC, including infection, hereditary conditions, and environmental factors, is of particular importance and is discussed in this review. To improve survival in GC, we also must improve our therapeutic strategies. Here, we discuss new targets that warrant further exploration.

Defining the Optimal Duration of Neoadjuvant Therapy for Pancreatic Ductal Adenocarcinoma: Time for a Personalized Approach?

ABSTRACT: Despite recent advances, pancreatic ductal adenocarcinoma (PDAC) continues to be associated with dismal outcomes, with a cure evading most patients. While historic treatment for PDAC has been surgical resection followed by 6 months of adjuvant therapy, there has been a recent shift toward neoadjuvant treatment (NAT). Several considerations support this approach, including the characteristic early systemic spread of PDAC, and the morbidity often surrounding pancreatic resection, which can delay recovery and preclude patients from starting adjuvant treatment. The addition of NAT has been suggested to improve margin-negative resection rates, decrease lymph node positivity, and potentially translate to improved survival. Conversely, complications and disease progression can occur during preoperative treatment, potentially eliminating the chance of curative resection. As NAT utilization has increased, treatment durations have been found to vary widely between institutions with an optimal duration remaining undefined. In this review, we assess the existing literature on NAT for PDAC, reviewing treatment durations reported across retrospective case series and prospective clinical trials to establish currently used approaches and seek the optimal duration. We also analyze markers of treatment response and review the potential for personalized approaches that may help clarify this important treatment question and move NAT toward a more standardized approach.

Tumor Size Differences Between Preoperative Endoscopic Ultrasound and Postoperative Pathology for Neoadjuvant-Treated Pancreatic Ductal Adenocarcinoma Predict Patient Outcome.

BACKGROUND & AIMS: The assessment of therapeutic response after neoadjuvant treatment and pancreatectomy for pancreatic ductal adenocarcinoma (PDAC) has been an ongoing challenge. Several limitations have been encountered when employing current grading systems for residual tumor. Considering endoscopic ultrasound (EUS) represents a sensitive imaging technique for PDAC, differences in tumor size between preoperative EUS and postoperative pathology after neoadjuvant therapy were hypothesized to represent an improved marker of treatment response. METHODS: For 340 treatment-naïve and 365 neoadjuvant-treated PDACs, EUS and pathologic findings were analyzed and correlated with patient overall survival (OS). A separate group of 200 neoadjuvant-treated PDACs served as a validation cohort for further analysis. RESULTS: Among treatment-naïve PDACs, there was a moderate concordance between EUS imaging and postoperative pathology for tumor size (r = 0.726, P < .001) and AJCC 8th edition T-stage (r = 0.586, P < .001). In the setting of neoadjuvant therapy, a decrease in T-stage correlated with improved 3-year OS rates (50% vs 31%, P < .001). Through recursive partitioning, a cutoff of ≥47% tumor size reduction was also found to be associated with improved OS (67% vs 32%, P < .001). Improved OS using a ≥47% threshold was validated using a separate cohort of neoadjuvant-treated PDACs (72% vs 36%, P < .001). By multivariate analysis, a reduction in tumor size by ≥47% was an independent prognostic factor for improved OS (P = .007). CONCLUSIONS: The difference in tumor size between preoperative EUS imaging and postoperative pathology among neoadjuvant-treated PDAC patients is an important prognostic indicator and may guide subsequent chemotherapeutic management.

Encouraging long-term survival following autophagy inhibition using neoadjuvant hydroxychloroquine and gemcitabine for high-risk patients with resectable pancreatic carcinoma.

INTRODUCTION: Preoperative autophagy inhibition with hydroxychloroquine (HCQ) in combination with gemcitabine in pancreatic adenocarcinoma (PDAC) has been shown to be safe and effective in inducing a serum biomarker response and increase resection rates in a previous phase I/II clinical trial. We aimed to analyze the long-term outcomes of preoperative HCQ with gemcitabine for this cohort. METHODS: A review of patients enrolled between July 2010 and February 2013 in the completed phase I/II single arm (two doses of fixed-dose gemcitabine (1500 mg/m2 ) in combination with oral hydroxychloroquine administered for 31 consecutive days until the day of surgery for high-risk pancreatic cancer) was undertaken. Progression-free survival (PFS) and overall survival analysis (OS) using Kaplan-Meier estimates were performed. RESULTS: Of 35 patients initially enrolled, 29 patients underwent surgical resection (median age at diagnosis: 62 years, 45% females). Median duration of follow-up was 7.5 years. There was a median 15% decrease in the serum CA19-9 levels following completion of neoadjuvant therapy and 83% of the cohort underwent a pancreaticoduodenectomy, 7 (24%) patients had a concomitant venous resection. On histopathology, 14 (48%) patients had at least a partial treatment response. The median PFS and OS were 11 months (95% Confidence interval [CI]: 7-28) and 31 months (95% CI: 13-47), respectively, while 9 (31%) patients survived beyond 5 years from diagnosis; a rate that compares very favorably with contemporaneous series. CONCLUSION: Compared to historical data, neoadjuvant autophagy inhibition with HCQ plus gemcitabine is associated with encouraging long-term survival for patients with PDAC.

Robot Assisted Distal Pancreatectomy with Celiac Axis Resection (DP-CAR) for Pancreatic Cancer: Surgical Planning and Technique.

Malignant pancreatic tumors involving the celiac artery can be resected with a distal pancreatectomy, splenectomy and celiac axis resection (DP-CAR), relying on collateral flow to the liver through the gastroduodenal artery (GDA). In the current manuscript, the technical conduct of robotic DP-CAR is outlined. The greater curve of the stomach is mobilized with care to avoid sacrificing the gastroepiploic vessels. The stomach and liver are retracted cephalad to facilitate dissection of the porta hepatis. The hepatic artery (HA) is dissected and encircled with a vessel loop. The gastroduodenal artery (GDA) is carefully preserved. The common HA is clamped and triphasic flow in the proper HA via the GDA is confirmed using intra-operative ultrasound. A retropancreatic tunnel is made over the superior mesenteric vein (SMV). The pancreas is divided with an endovascular stapler at the neck. The inferior mesenteric vein (IMV) and splenic vein are ligated. The HA is stapled proximal to the GDA. The entire specimen is retracted laterally with further dissection cephalad to expose the superior mesenteric artery (SMA). The SMA is then traced back to the aorta. The dissection continues cephalad along the aorta with the bipolar energy device used to divide the crural fibers and celiac nerve plexus. The specimen is mobilized from the patient's right to left until the origin of the celiac axis is identified and oriented towards the left. The trunk is circumferentially dissected and stapled. Additional dissection with hook cautery and the bipolar energy device fully mobilizes the pancreatic tail and spleen. The specimen is removed from the left lower quadrant extraction site and one drain is left in the resection bed. A final intra-operative ultrasound of the proper HA confirms pulsatile, triphasic flow in the artery and liver parenchyma. The stomach is inspected for evidence of ischemia. Robotic DP-CAR is safe, feasible and when used in conjunction with multi-modality therapy, offers potential for long-term survival in selected patients.

Development of a Senior Medical Student Robotic Surgery Training Elective.

As robotic surgery has become more widespread, early exposure to the robotic platform is becoming increasingly important, not only to graduate medical education, but also for medical students pursuing surgical residency. In an effort to orient students to robotic technology and decrease the learning curve for what is likely to become an integral part of residency training, we created a formal, elective robotic surgery curriculum for senior medical students. Throughout this 2-week fourth year rotation, students completed online training modules and assessment; mastered exercises on the simulator system related to the console, camera, energy, dexterity, and suturing skills; attended didactics; utilized the dual console during one-on-one simulation lab sessions with attending robotic surgery experts; and translated new skills to biotissue anastomoses as well as bedside-assisting in the operating room. During cases, students were able to have more meaningful observation experiences, recognizing the significance of various robotic approaches employed and utilization of specific instruments. Future aims of this rotation will assess student experience as it impacts readiness for surgical residency.

Immune Cell Modulation of the Extracellular Matrix Contributes to the Pathogenesis of Pancreatic Cancer.

Pancreatic ductal adenocarcinoma (PDAC) is a highly lethal malignancy with a five-year survival rate of only 9%. PDAC is characterized by a dense, fibrotic stroma composed of extracellular matrix (ECM) proteins. This desmoplastic stroma is a hallmark of PDAC, representing a significant physical barrier that is immunosuppressive and obstructs penetration of cytotoxic chemotherapy agents into the tumor microenvironment (TME). Additionally, dense ECM promotes hypoxia, making tumor cells refractive to radiation therapy and alters their metabolism, thereby supporting proliferation and survival. In this review, we outline the significant contribution of fibrosis to the pathogenesis of pancreatic cancer, with a focus on the cross talk between immune cells and pancreatic stellate cells that contribute to ECM deposition. We emphasize the cellular mechanisms by which neutrophils and macrophages, specifically, modulate the ECM in favor of PDAC-progression. Furthermore, we investigate how activated stellate cells and ECM influence immune cells and promote immunosuppression in PDAC. Finally, we summarize therapeutic strategies that target the stroma and hinder immune cell promotion of fibrogenesis, which have unfortunately led to mixed results. An enhanced understanding of the complex interactions between the pancreatic tumor ECM and immune cells may uncover novel treatment strategies that are desperately needed for this devastating disease.