Hepatic adenoma: evolution of a more individualized treatment approach

BACKGROUND

Hepatic adenomas (HAs) are benign, solid liver lesions, which carry a risk of hemorrhage and malignant transformation. This review article highlights the advances in the diagnosis and management of HAs.

METHODS

A comprehensive review was performed using MEDLINE/PubMed and Web of Science databases with a search period ending on September 30, 2023. Using PubMed, the terms "hepatocellular," "hepatic," and "adenoma" were searched.

RESULTS

HA has been classified into at least 8 subtypes based on molecular pathology, each exhibiting unique histopathologic features, clinical considerations, and risk of malignant transformation. The most common subtype is inflammatory HA, followed by hepatocyte nuclear factor 1α-inactivated HA, β-catenin exon 3-mutated HA (βex3-HA), β-catenin exon 7- or 8-mutated HA, sonic hedgehog HA, and unclassified HA. Magnetic resonance imaging is the best imaging method for diagnosis and can distinguish among HA subtypes based on fat and telangiectasia pathologic characteristics. The risk of malignant transformation varies among molecular subtypes, ranging from <1% to approximately 50%. Up to 42% of HAs present with spontaneous intratumoral hemorrhage and peritoneal hemorrhage. In general, only 15% to 20% of patients require surgery. HA larger than 5 cm are more likely to be complicated by bleeding and malignant transformation, regardless of subtype, and should generally be resected. In particular, βex3-HA carries a high risk of malignant transformation and can be considered a true precancerous lesion.

CONCLUSION

The management of HAs is based on a multidisciplinary approach. Clinical decision-making should integrate information on gender, tumor size, and HA subtyping. In the future, patients with HA will benefit from novel medical therapies tailored to the individual molecular subtypes.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Update on Targeted Therapy and Immunotherapy for Metastatic Colorectal Cancer

Metastatic colorectal cancer remains a deadly malignancy and is the third leading cause of cancer-related death. The mainstay of treatment for metastatic colorectal cancer is chemotherapy, but unfortunately, even with recent progress, overall survival is still poor. Colorectal cancer is a heterogeneous disease, and the underlying genetic differences among tumors can define the behavior and prognosis of the disease. Given the limitations of cytotoxic chemotherapy, research has focused on developing targeted therapy based on molecular subtyping. Since the early 2000s, multiple targeted therapies have demonstrated efficacy in treating metastatic colorectal cancer and have received FDA approval. The epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), and DNA mismatch repair pathways have demonstrated promising results for targeted therapies. As new gene mutations and proteins involved in the oncogenesis of metastatic colorectal cancer are identified, new targets will continue to emerge. We herein provide a summary of the updated literature regarding targeted therapies for patients with mCRC.

Discovery of KRB-456, a KRAS G12D Switch-I/II Allosteric Pocket Binder That Inhibits the Growth of Pancreatic Cancer Patient-derived Tumors

Currently, there are no clinically approved drugs that directly thwart mutant KRAS G12D, a major driver of human cancer. Here, we report on the discovery of a small molecule, KRB-456, that binds KRAS G12D and inhibits the growth of pancreatic cancer patient-derived tumors. Protein nuclear magnetic resonance studies revealed that KRB-456 binds the GDP-bound and GCP-bound conformation of KRAS G12D by forming interactions with a dynamic allosteric binding pocket within the switch-I/II region. Isothermal titration calorimetry demonstrated that KRB-456 binds potently to KRAS G12D with 1.5-, 2-, and 6-fold higher affinity than to KRAS G12V, KRAS wild-type, and KRAS G12C, respectively. KRB-456 potently inhibits the binding of KRAS G12D to the RAS-binding domain (RBD) of RAF1 as demonstrated by GST-RBD pulldown and AlphaScreen assays. Treatment of KRAS G12D-harboring human pancreatic cancer cells with KRB-456 suppresses the cellular levels of KRAS bound to GTP and inhibits the binding of KRAS to RAF1. Importantly, KRB-456 inhibits P-MEK, P-AKT, and P-S6 levels in vivo and inhibits the growth of subcutaneous and orthotopic xenografts derived from patients with pancreatic cancer whose tumors harbor KRAS G12D and KRAS G12V and who relapsed after chemotherapy and radiotherapy. These results warrant further development of KRB-456 for pancreatic cancer.

SIGNIFICANCE

There are no clinically approved drugs directly abrogating mutant KRAS G12D. Here, we discovered a small molecule, KRB-456, that binds a dynamic allosteric binding pocket within the switch-I/II region of KRAS G12D. KRB-456 inhibits P-MEK, P-AKT, and P-S6 levels in vivo and inhibits the growth of subcutaneous and orthotopic xenografts derived from patients with pancreatic cancer. This discovery warrants further advanced preclinical and clinical studies in pancreatic cancer.

Changing Practice Patterns and Improving Survival for Patients with Pancreatic Ductal Adenocarcinoma

Over the last two decades, there have been many reported advances in the clinical management of pancreatic ductal adenocarcinoma (PDAC). We sought to evaluate changes in survival for patients diagnosed with PDAC between 2004 and 2017. The National Cancer Database was queried for patients diagnosed with PDAC between 2004 and 2017. There were 55,401 patients who underwent surgery and 109,477 patients who underwent non-surgical treatment for PDAC between 2004 and 2017. Patients were categorized into four groups by year of diagnosis. Median survival improved from 15.5 months to 25.3 months for patients treated with surgery between the years 2016 and 2017 compared with between 2004 and 2007 (p < 0.001). Median survival improved from 7.2 months to 10.1 months for patients treated without surgery during the same years (p < 0.001). On multivariable analysis, the hazard ratio for death was estimated to multiply by 0.975 per year for patients treated with surgery and 0.959 per year for patients treated without surgery (p < 0.001). This increase in survival in the setting of evolving care validates continued efforts aimed at improving survival for patients with this devastating disease.

A protein-based machine learning approach to the identification of inflammatory subtypes in pancreatic ductal adenocarcinoma

BACKGROUND/OBJECTIVES

The inherently immunosuppressive tumor microenvironment along with the heterogeneity of pancreatic ductal adenocarcinoma (PDAC) limits the effectiveness of available treatment options and contributes to the disease lethality. Using a machine learning algorithm, we hypothesized that PDAC may be categorized based on its microenvironment inflammatory milieu.

METHODS

Fifty-nine tumor samples from patients naïve to treatment were homogenized and probed for 41 unique inflammatory proteins using a multiplex assay. Subtype clustering was determined using t-distributed stochastic neighbor embedding (t-SNE) machine learning analysis of cytokine/chemokine levels. Statistics were performed using Wilcoxon rank sum test and Kaplan-Meier survival analysis.

RESULTS

t-SNE analysis of tumor cytokines/chemokines revealed two distinct clusters, immunomodulating and immunostimulating. In pancreatic head tumors, patients in the immunostimulating group (N = 26) were more likely to be diabetic (p = 0.027), but experienced less intraoperative blood loss (p = 0.0008). Though there were no significant differences in survival (p = 0.161), the immunostimulating group trended toward longer median survival by 9.205 months (11.28 vs. 20.48 months).

CONCLUSION

A machine learning algorithm identified two distinct subtypes within the PDAC inflammatory milieu, which may influence diabetes status as well as intraoperative blood loss. Opportunity exists to further explore how these inflammatory subtypes may influence treatment response, potentially elucidating targetable mechanisms of PDAC's immunosuppressive tumor microenvironment.

Resource use for cholecystectomy with versus without cholangiography: A multicenter, propensity-matched analysis

BACKGROUND

Intraoperative cholangiography may allow for earlier identification of common bile duct injury and choledocholithiasis. The role of intraoperative cholangiography in decreasing resource use related to biliary pathology remains unclear. This study tests the null hypothesis that there is no difference in resource use for patients undergoing laparoscopic cholecystectomy with versus without intraoperative cholangiography.

METHODS

This retrospective, longitudinal cohort study included 3,151 patients who underwent laparoscopic cholecystectomy at 3 university hospitals. To minimize differences in baseline characteristics while maintaining adequate statistical power, propensity scores were used to match 830 patients who underwent intraoperative cholangiography at surgeon discretion and 795 patients who underwent cholecystectomy without intraoperative cholangiography. Primary outcomes were the incidence of postoperative endoscopic retrograde cholangiography, the interval between surgery and endoscopic retrograde cholangiography, and total direct costs.

RESULTS

In the propensity-matched analysis, the intraoperative cholangiography and no intraoperative cholangiography cohorts had similar age, comorbidities, American Society of Anesthesiologists Sequential Organ Failure Assessment scores, and total/direct bilirubin ratios. The intraoperative cholangiography cohort had a lower postoperative endoscopic retrograde cholangiography (2.4% vs 4.3%; P = .04), a shorter interval between cholecystectomy and endoscopic retrograde cholangiography (2.5 [1.0-17.8] vs 4.5 [2.0-9.5] days; P = .04), and shorter length of stay (0.3 [0.2-1.5] vs 1.4 [0.3-3.2] days; P < .001). Patients undergoing intraoperative cholangiography had lower total direct costs ($4.0K [3.6K-5.4K] vs $8.1K [4.9K-13.0K]; P < .001). There were no differences in 30-day or 1-year mortality among the cohorts.

CONCLUSION

Compared with laparoscopic cholecystectomy without intraoperative cholangiography, cholecystectomy with intraoperative cholangiography was associated with decreased resource use, which was primarily attributable to decreased incidence and the earlier timing of postoperative endoscopic retrograde cholangiography.

A simulation curriculum for laparoscopic common bile duct exploration, balloon sphincterotomy, and endobiliary stenting: Associations with resident performance and autonomy in the operating room

BACKGROUND

Laparoscopic common bile duct exploration is safe and effective for managing choledocholithiasis, but laparoscopic common bile duct exploration is rarely performed, which threatens surgical trainee proficiency. This study tests the hypothesis that prior operative or simulation experience with laparoscopic common bile duct exploration is associated with greater resident operative performance and autonomy without adversely affecting patient outcomes.

METHODS

This longitudinal cohort study included 33 consecutive patients undergoing laparoscopic common bile duct exploration in cases involving postgraduate years 3, 4, and 5 general surgery residents at a single institution during the implementation of a laparoscopic common bile duct exploration simulation curriculum. For each of the 33 cases, resident performance and autonomy were rated by residents and attendings, the resident's prior operative and simulation experience were recorded, and patient outcomes were ascertained from electronic health records for comparison among 3 cohorts: prior operative experience, prior simulation experience, and no prior experience.

RESULTS

Operative approach was similar among cohorts. Overall morbidity was 6.1% and similar across cohorts. The operative performance scores were higher in prior experience cohorts according to both residents (3.0 [2.8-3.0] vs 2.0 [2.0-3.0]; P = .01) and attendings (3.0 [3.0-4.0]; P < .001). The autonomy scores were higher in prior experience cohorts according to both residents (2.0 [2.0-3.0] vs 2.0 [2.0-2.0]; P = .005) and attendings (2.5 [2.0-3.0] vs 2.0 [1.0-2.0]; P = .001). Prior simulation and prior operative experience had similar associations with performance and autonomy.

CONCLUSION

Simulation experience with laparoscopic common bile duct exploration was associated with greater resident operative performance and autonomy, with effects that mimic prior operative experience. This illustrates the potential for simulation-based training to improve resident operative performance and autonomy for laparoscopic common bile duct exploration.

Surgical resident experience with common bile duct exploration and assessment of performance and autonomy with formative feedback

BACKGROUND

Common bile duct exploration (CBDE) is safe and effective for managing choledocholithiasis, but most US general surgeons have limited experience with CBDE and are uncomfortable performing this procedure in practice. Surgical trainee exposure to CBDE is limited, and their learning curve for achieving autonomous, practice-ready performance has not been previously described. This study tests the hypothesis that receipt of one or more prior CBDE operative performance assessments, combined with formative feedback, is associated with greater resident operative performance and autonomy.

METHODS

Resident and attending assessments of resident operative performance and autonomy were obtained for 189 laparoscopic or open CBDEs performed at 28 institutions. Performance and autonomy were graded along validated ordinal scales. Cases in which the resident had one or more prior CBDE case evaluations (n = 48) were compared with cases in which the resident had no prior evaluations (n = 141).

RESULTS

Compared with cases in which the resident had no prior CBDE case evaluations, cases with a prior evaluation had greater proportions of practice-ready or exceptional performance ratings according to both residents (27% vs. 11%, p = .009) and attendings (58% vs. 19%, p < .001) and had greater proportions of passive help or supervision only autonomy ratings according to both residents (17% vs. 4%, p = .009) and attendings (69% vs. 32%, p < .01).

CONCLUSIONS

Residents with at least one prior CBDE evaluation and formative feedback demonstrated better operative performance and received greater autonomy than residents without prior evaluations, underscoring the propensity of feedback to help residents achieve autonomous, practice-ready performance for rare operations.

Transcriptomic analysis of pancreatic adenocarcinoma specimens obtained from Black and White patients

In pancreatic cancer clinical trials, Black patients are under-represented while having higher morbidity and mortality rates as compared to other racial groups. Multiple factors, including socioeconomic and lifestyle factors may contribute to this disparity, but genomic contributions remain unclear. In an exploratory project to identify genes that may contribute to differences in survival between Black (n = 8) and White (n = 20) patients with pancreatic cancer, transcriptomic sequencing of over 24,900 genes was performed in human pancreatic tumor and non-tumor tissue obtained from Black and White patients. Over 4,400 genes were differentially expressed in tumor and non-tumor tissue, irrespective of race. To validate these results, the expression of four genes (AGR2, POSTN, TFF1, and CP) reported to be up-regulated in pancreatic tumor tissue as compared to non-tumor tissue were confirmed using quantitative PCR. Transcriptomic analysis that compared pancreatic tumor tissue from Black and White patients revealed differential expression in 1,200 genes, while a comparison of the non-tumor and tumor gene expression differences within each race revealed over 1,500 tumor-specific differentially expressed genes in pancreatic tumor and non-tumor tissue from Black patients. We identified TSPAN8 as a potential tumor-specific gene significantly overexpressed in pancreatic tumor tissue in Black patients as compared to White patients. Using Ingenuity Pathway Analysis software to compare the race-associated gene expression profiles, over 40 canonical pathways were identified to be potentially impacted by the gene expression differences between the races. Heightened expression of TSPAN8 was associated with poor overall survival, suggesting TSPAN8 as one potential genetic factor contributing to the differential outcomes in Black patients with pancreatic cancer, supporting the potential utility of larger genomic studies to further explore the role of TSPAN8 in pancreatic cancer.

The interleukin-1 axis and the tumor immune microenvironment in pancreatic ductal adenocarcinoma

Interleukin-1 (IL-1) plays a key role in carcinogenesis and several IL-1-targeted therapeutics are under investigation for the treatment of pancreatic ductal adenocarcinoma (PDAC). We sought to broaden our understanding of how the family of IL-1 ligands and receptors impact the tumor immune landscape and patient survival in PDAC. Gene expression data and DNA methylation data for IL1A, IL1B, IL1RN, IL1R1, IL1R2, and IL1RAP was attained from The Cancer Genome Atlas (TCGA) database and cross validated using the National Center for Biotechnology Information (NCBI) Gene Expression Omnibus (GEO) database. Immune cell-type abundance was estimated using CIBERSORTx. Further confirmatory soluble protein analysis and peripheral blood immunophenotyping were performed on available tissue samples from our institution. 169 PDAC patients and 50 benign pancreatic TCGA-based samples were analyzed. IL1A (p < 0.001), IL1RN (p < 0.001), IL1R2 (p < 0.001), and IL1RAP (p = 0.006) were markedly increased in PDAC tumor tissue compared to benign pancreatic tissue. Furthermore, expression of IL1A, IL1B and IL1R1 were positively correlated with gene expression of immune checkpoints PVR, CD274, CD47, CD80, and HLA-A/B/C (p < 0.001). IL1B and IL1R1 were correlated to expression of PDCD1, CD86, CTLA4 and IDO1 (<0.001). Low expression of IL1RN (p = 0.020), IL1R2 (p = 0.015), and IL1RAP (p = 0.003) and high expression of IL1B (p = 0.031) were correlated with increased patient survival. At the protein level, IL-1β was correlated with increased peripheral central memory CD4+ and CD8+ T-cells as well as decreased Th2 cells. These findings suggest that the IL-1 axis plays a complex and pivotal role in the host immune response to PDAC.

Calcium channel blockers potentiate gemcitabine chemotherapy in pancreatic cancer

There is currently no effective treatment for pancreatic ductal adenocarcinoma (PDAC). While palliative chemotherapy offers a survival benefit to most patients, nearly all will eventually progress on treatment and long-term survivability remains poor. Given the lack of subsequent line treatment options, in this study, we sought to identify novel strategies to prevent, delay, or overcome resistance to gemcitabine, one of the most widely used medications in PDAC. Using a combination of single-cell RNA sequencing and high-throughput proteomic analysis, we identified a subset of gemcitabine-resistant tumor cells enriched for calcium/calmodulin signaling. Pharmacologic inhibition of calcium-dependent calmodulin activation led to the rapid loss of drug-resistant phenotypes in vitro, which additional single-cell RNA sequencing identified was due to impaired activation of the RAS/ERK signaling pathway. Consistent with these observations, calcium chelation or depletion of calcium in the culture media also impaired ERK activation in gemcitabine-resistant cells, and restored therapeutic responses to gemcitabine in vitro. We observed similar results using calcium channel blockers (CCBs) such as amlodipine, which inhibited prosurvival ERK signaling in vitro and markedly enhanced therapeutic responses to gemcitabine in both orthotopic xenografts and transgenic models of PDAC. Combined, these results offer insight into a potential means of gemcitabine resistance and suggest that select CCBs may provide a clinical benefit to PDAC patients receiving gemcitabine-based chemotherapy.

Loss of SMAD4 Is Associated With Poor Tumor Immunogenicity and Reduced PD-L1 Expression in Pancreatic Cancer

Transforming Growth Factor β (TGFβ) is a key mediator of immune evasion in pancreatic ductal adenocarcinoma (PDAC), and the addition of TGFβ inhibitors in select immunotherapy regimens shows early promise. Though the TGFβ target SMAD4 is deleted in approximately 55% of PDAC tumors, the effects of SMAD4 loss on tumor immunity have yet to be fully explored. Using a combination of genomic databases and PDAC specimens, we found that tumors with loss of SMAD4 have a comparatively poor T-cell infiltrate. SMAD4 loss was also associated with a reduction in several chemokines with known roles in T-cell recruitment, which was recapitulated using knockdown of SMAD4 in PDAC cell lines. Accordingly, JURKAT T-cells were poorly attracted to conditioned media from PDAC cells with knockdown of SMAD4 and lost their ability to produce IFNγ. However, while exogenous TGFβ modestly reduced PD-L1 expression in SMAD4-intact cell lines, SMAD4 and PD-L1 positively correlated in human PDAC samples. PD-L1 status was closely related to tumor-infiltrating lymphocytes, particularly IFNγ-producing T-cells, which were more abundant in SMAD4-expressing tumors. Low concentrations of IFNγ upregulated PD-L1 in tumor cells in vitro, even when administered alongside high concentrations of TGFβ. Hence, while SMAD4 may have a modest inhibitory effect on PD-L1 in tumor cells, SMAD4 indirectly promotes PD-L1 expression in the pancreatic tumor microenvironment by enhancing T-cell infiltration and IFNγ biosynthesis. These data suggest that pancreatic cancers with loss of SMAD4 represent a poorly immunogenic disease subtype, and SMAD4 status warrants further exploration as a predictive biomarker for cancer immunotherapy.

Overcoming Gemcitabine Resistance in Pancreatic Cancer Using the BCL-XL-Specific Degrader DT2216

Pancreatic cancer is the third most common cause of cancer-related deaths in the United States. Although gemcitabine is the standard of care for most patients with pancreatic cancer, its efficacy is limited by the development of resistance. This resistance may be attributable to the evasion of apoptosis caused by the overexpression of BCL-2 family antiapoptotic proteins. In this study, we investigated the role of BCL-XL in gemcitabine resistance to identify a combination therapy to more effectively treat pancreatic cancer. We used CRISPR-Cas9 screening to identify the key genes involved in gemcitabine resistance in pancreatic cancer. Pancreatic cancer cell dependencies on different BCL-2 family proteins and the efficacy of the combination of gemcitabine and DT2216 (a BCL-XL proteolysis targeting chimera or PROTAC) were determined by MTS, Annexin-V/PI, colony formation, and 3D tumor spheroid assays. The therapeutic efficacy of the combination was investigated in several patient-derived xenograft (PDX) mouse models of pancreatic cancer. We identified BCL-XL as a key mediator of gemcitabine resistance. The combination of gemcitabine and DT2216 synergistically induced cell death in multiple pancreatic cancer cell lines in vitro In vivo, the combination significantly inhibited tumor growth and prolonged the survival of tumor-bearing mice compared with the individual agents in pancreatic cancer PDX models. Their synergistic antitumor activity is attributable to DT2216-induced degradation of BCL-XL and concomitant suppression of MCL-1 by gemcitabine. Our results suggest that DT2216-mediated BCL-XL degradation augments the antitumor activity of gemcitabine and their combination could be more effective for pancreatic cancer treatment.

Osteopenia is associated with wasting in pancreatic adenocarcinoma and predicts survival after surgery

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest of all common malignancies. Treatment is difficult and often complicated by the presence of cachexia. The clinical portrait of cachexia contributes to the poor prognosis experienced by PDAC patients and worsens therapeutic outcomes. We propose that low bone mineral density is a component of cachexia, which we explore herein through a retrospective review of all patients at our facility that underwent surgery for PDAC between 2011 and 2018 and compared to sex-, age- and comorbidity-matched control individuals. Data were abstracted from the medical record and pre-operative computed tomography scans. Muscle mass and quality were measured at the L3 level and bone mineral density was measured as the radiation attenuation of the lumbar vertebral bodies. Patients with PDAC displayed typical signs of cachexia such as weight loss and radiologically appreciable deterioration of skeletal muscle. Critically, PDAC patients had significantly lower bone mineral density than controls, with 61.2% of PDAC patients categorized as osteopenic compared to 36.8% of controls. PDAC patients classified as osteopenic had significantly reduced survival (1.01 years) compared to patients without osteopenia (2.77 years). The presence of osteopenia was the strongest clinical predictor of 1- and 2-year disease-specific mortality, increasing the risk of death by 107% and 80%, respectively. Osteopenia serves as a test of 2-year mortality with sensitivity of 76% and specificity of 58%. These data therefore identify impaired bone mineral density as a key component of cachexia and predictor of postoperative survival in patients with PDAC. The mechanisms that lead to bone wasting in tumor-bearing hosts deserve further study.

It's more than just cancer biology: Health disparities in patients with pancreatic neuroendocrine tumors

BACKGROUND AND OBJECTIVES

Pancreatic neuroendocrine tumors (PNETs) represent a rare form of pancreatic cancer. Racial/ethnic disparities have been documented in pancreatic ductal adenocarcinoma, but health disparities have not been well described in patients with PNETs.

METHODS

A retrospective review of patients with PNETs in the National Cancer Database was performed for 2004-2014. Approximately 16 605 patients with PNETs and available vital status were identified. Survival was compared by race/ethnicity and socioeconomic status using Kaplan-Meier methods and Cox regression.

RESULTS

There were no significant differences in survival between Non-Hispanic, White; Hispanic, White; or Non-Hispanic, Black patients on univariate analysis. Kaplan-Meier analysis showed that patients from communities with lower median household income and education level had worse survival (p < 0.001). Patients age less than 65 without insurance, similarly, had worse survival (p < 0.001). Multivariable modeling found no association between race/ethnicity and risk of mortality (p = 0.37). Lower median household income and lower education level were associated with increased mortality (p < 0.001).

CONCLUSIONS

Unlike most other malignancies, race/ethnicity is not associated with survival differences in patients with PNETs. Patients with lower socioeconomic status had worse survival. The presence of identifiable health disparities in patients with PNETs represents a target for intervention and opportunity to improve survival in patients with this malignancy.

The Current Treatment Paradigm for Pancreatic Ductal Adenocarcinoma and Barriers to Therapeutic Efficacy

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis, with a median survival time of 10-12 months. Clinically, these poor outcomes are attributed to several factors, including late stage at the time of diagnosis impeding resectability, as well as multi-drug resistance. Despite the high prevalence of drug-resistant phenotypes, nearly all patients are offered chemotherapy leading to modest improvements in postoperative survival. However, chemotherapy is all too often associated with toxicity, and many patients elect for palliative care. In cases of inoperable disease, cytotoxic therapies are less efficacious but still carry the same risk of serious adverse effects, and clinical outcomes remain particularly poor. Here we discuss the current state of pancreatic cancer therapy, both surgical and medical, and emerging factors limiting the efficacy of both. Combined, this review highlights an unmet clinical need to improve our understanding of the mechanisms underlying the poor therapeutic responses seen in patients with PDAC, in hopes of increasing drug efficacy, extending patient survival, and improving quality of life.

Preclinical Models of Pancreatic Ductal Adenocarcinoma and Their Utility in Immunotherapy Studies

Simple Summary

Immune checkpoint blockade has provided durable clinical responses in a number of human malignancies, but not in patients with pancreatic cancer. Efforts to understand mechanisms of resistance and increase efficacy of immune checkpoint blockade in pancreatic cancer require the use of appropriate preclinical models in the laboratory. Here, we discuss the benefits, caveats, and potentials for improvement of the most commonly used models, including murine-based and patient-derived models.

Abstract

The advent of immunotherapy has transformed the treatment landscape for several human malignancies. Antibodies against immune checkpoints, such as anti-PD-1/PD-L1 and anti-CTLA-4, demonstrate durable clinical benefits in several cancer types. However, checkpoint blockade has failed to elicit effective anti-tumor responses in pancreatic ductal adenocarcinoma (PDAC), which remains one of the most lethal malignancies with a dismal prognosis. As a result, there are significant efforts to identify novel immune-based combination regimens for PDAC, which are typically first tested in preclinical models. Here, we discuss the utility and limitations of syngeneic and genetically-engineered mouse models that are currently available for testing immunotherapy regimens. We also discuss patient-derived xenograft mouse models, human PDAC organoids, and ex vivo slice cultures of human PDAC tumors that can complement murine models for a more comprehensive approach to predict response and resistance to immunotherapy regimens.

Abstract 955: Long-term gemcitabine treatment reshapes the pancreatic tumor microenvironment and sensitizes murine carcinoma to combination immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related death with a median survival time of 6-12 months. As most patients present with disseminated disease, the majority are offered palliative chemotherapy. With no approved treatment modalities for patients who progress on chemotherapy, we explored the effects of long-term Gemcitabine on the tumor microenvironment in order to identify potential therapeutic options in chemo-refractory PDAC. Using a combination of mouse models, patient-derived xenografts, primary and established cell lines, we first evaluated chemotherapy-induced alterations in the tumor secretome and immune surface proteins by high throughput proteomic arrays. In addition to enhancing antigen presentation and immune checkpoint expression, Gemcitabine consistently increased the synthesis of CCL/CXCL chemokines and TGFβ-associated signals. These secreted factors altered the composition of the tumor stroma, conferring Gemcitabine-resistance to cancer-associated fibroblasts in vitroand further enhancingTGFβ1 biosynthesis. We therefore combined Gemcitabine with anti-PD-1 in transgenic models of murine PDAC, which failed to alter disease course unless mice also underwent genetic or pharmacologic ablation of TGFβ signaling. In the setting of TGFβ signal deficiency, Gemcitabine and anti-PD-1 led to a robust CD8+ T-cell response and decrease in tumor burden, markedly enhancing overall survival. These results suggest that Gemcitabine may prime PDAC tumors for immune checkpoint inhibition by enhancing antigen presentation, but requires the inhibition of an immunosuppressive cytokine barrier. Given the current lack of third line treatment options, this approach warrants consideration in the clinical management of Gemcitabine-refractory PDAC.

Citation Format: Daniel R. Principe, Matthew Narbutis, Sandeep Kumar, Alex Park, Navin Viswakarma, Matthew J. Dorman, Suneel D. Kamath, Paul Grippo, Melissa L. Fishel, Rosa F. Hwang, Dinesh Thummuri, Patrick W. Underwood, Hidayatullah G. Munshi, Jose G. Trevino, Ajay Rana. Long-term gemcitabine treatment reshapes the pancreatic tumor microenvironment and sensitizes murine carcinoma to combination immunotherapy [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 955.

Abstract 1172: Disparities in pancreatic ductal adenocarcinoma - the significance of Hispanic ethnicity, by subgroup analysis, and treatment facility on clinical outcomes

Background: Disparities exist among patients with pancreatic ductal adenocarcinoma (PDAC). Non-White race is regarded as a negative predictor of expected treatment and overall survival. Data suggest Academic Research Programs (ARP) provide better outcomes for minorities, but ethnic/minority outcomes are underreported. We sought to evaluate outcomes among diverse patients with PDAC, with a focus on Hispanic subgroups. We hypothesize that outcomes among racially/ethnically diverse PDAC patients may be influenced by treatment facility.

Methods: The National Cancer Database was used to identify 170,327 patients diagnosed with PDAC between 2004 and 2015. Cox proportional-hazard regression was used to compare survival between race/ethnic groups across facilities.

Results: In unadjusted models, compared to Non-Hispanic Whites (NHW), Non-Hispanic Blacks (NHB) had the worst overall survival (HR=1.05, 95%CI:1.03-1.06, p&lt;0.001) and Hispanics had the best overall survival (HR=0.92, 95%CI:0.90-0.94, p&lt;0.001). After controlling for socioeconomic and clinical covariates, NHB (HR=0.95, 95%CI:0.93-0.96, p&lt;0.001) had better overall survival compared to NHW, and Hispanics continued to have the best comparative outcomes (HR=0.84, 95%CI:0.82-0.86, p&lt;0.001). Amongst Hispanics, Dominicans and South/Central Americans lived the longest, at 10.25 and 9.82 months, respectively. The improved survival in Hispanics was most pronounced at ARP (HR=0.80, 95%CI:0.77-0.84, p&lt;0.001) and Integrated Network Cancer Programs (HR=0.78, 95%CI:0.73-0.84, p&lt;0.001). NHB had improved survival over NHW at Comprehensive Community Care Programs (HR=0.96, 95%CI:0.93-0.98, p=0.002) and ARP (HR=0.96, 95%CI:0.94-0.98, p=0.001), which was influenced by income, education, and surgical resection.

Conclusion: Hispanics with PDAC have better overall survival compared to Non-Hispanics at all facilities, but most profoundly at ARP and INCP. Dominicans and South/Central Americans in particular have significantly improved survival at ARP. Survival was improved at ARP for all populations. NHB had improved overall survival at higher volume centers, but this was dependent upon income, education, and surgical resection.

Citation Format: Andrea N. Riner, Patrick W. Underwood, Kai Yang, Kelly M. Herremans, Miles E. Cameron, Srikar Chamala, Peihua Qiu, Thomas George, Jennifer Permuth, Nipun B. Merchant, Jose G. Trevino. Disparities in pancreatic ductal adenocarcinoma - the significance of Hispanic ethnicity, by subgroup analysis, and treatment facility on clinical outcomes [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 1172.

Long-Term Gemcitabine Treatment Reshapes the Pancreatic Tumor Microenvironment and Sensitizes Murine Carcinoma to Combination Immunotherapy

Pancreatic ductal adenocarcinoma (PDAC) is a leading cause of cancer-related death with a median survival time of 6-12 months. Most patients present with disseminated disease and the majority are offered palliative chemotherapy. With no approved treatment modalities for patients who progress on chemotherapy, we explored the effects of long-term gemcitabine administration on the tumor microenvironment to identify potential therapeutic options for chemorefractory PDAC. Using a combination of mouse models, primary cell line-derived xenografts, and established tumor cell lines, we first evaluated chemotherapy-induced alterations in the tumor secretome and immune surface proteins by high throughput proteomic arrays. In addition to enhancing antigen presentation and immune checkpoint expression, gemcitabine consistently increased the synthesis of CCL/CXCL chemokines and TGFβ-associated signals. These secreted factors altered the composition of the tumor stroma, conferring gemcitabine resistance to cancer-associated fibroblasts in vitro and further enhancing TGFβ1 biosynthesis. Combined gemcitabine and anti-PD-1 treatment in transgenic models of murine PDAC failed to alter disease course unless mice also underwent genetic or pharmacologic ablation of TGFβ signaling. In the setting of TGFβ signaling deficiency, gemcitabine and anti-PD-1 led to a robust CD8⁺ T-cell response and decrease in tumor burden, markedly enhancing overall survival. These results suggest that gemcitabine successfully primes PDAC tumors for immune checkpoint inhibition by enhancing antigen presentation only following disruption of the immunosuppressive cytokine barrier. Given the current lack of third-line treatment options, this approach warrants consideration in the clinical management of gemcitabine-refractory PDAC. SIGNIFICANCE: These data suggest that long-term treatment with gemcitabine leads to extensive reprogramming of the pancreatic tumor microenvironment and that patients who progress on gemcitabine-based regimens may benefit from multidrug immunotherapy.See related commentary by Carpenter et al., p. 3070 GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/15/3101/F1.large.jpg.

Abstract A106: Key differences in muscular index and tumor burden reveal unique biology in ethnically diverse patients with pancreatic cancer

Introduction: The racial disparities in pancreatic cancer (PC), while not fully appreciated, are recognized amongst PC experts. African Americans are diagnosed more frequently, present with more advanced disease, and suffer from higher mortality rates than White patients. Overall, cancer cachexia, or cancer-associated muscle wasting, greatly contributes to both morbidity and mortality. While cachexia is experienced by more than 80% of patients with PC, PC-induced cachexia and how it contributes to a disparity amongst African Americans is under investigation. African Americans with PC present with increased muscle wasting (-29%) than their White counterparts with PC (-14%). Therefore, we hypothesize that an established radiographically obtained muscular index (a psoas index) uniquely corresponds to increased disease burden in African Americans with early-stage disease.

Methods: African American and White patients with pancreatic ductal adenocarcinoma who underwent surgery at our institution between 2010 and 2017 were included in this retrospective study. A muscular index for each patient was measured from preoperative CT scans by dividing the average area of the psoas muscles at L3 by the L3 vertebral body area to normalize the measurement for patient size. Supplementary relevant clinical, pathologic, and laboratory values were used for comparison.

Results: 15 African American and 15 White surgical patients with PC were matched by gender and history of neoadjuvant therapy; age was similar in both groups (65.7 vs. 64.3, p=0.6566). Gross tumor size was similar in African Americans and Whites (2.553 vs. 3.093, p=0.3097). Tumor size, however, inversely correlated to psoas index in African Americans (r=0.4330, p=0.0077), but not in Whites (r=0.002525, p=0.8588). African Americans with lower psoas indices generally had larger tumors. Similar to tumor size, the positive lymph node ratio (LNR) inversely correlated to psoas index in African Americans (r=0.3930, p=0.0124), but not in Whites (r=0.08673, p=0.2867). LNR was significantly greater in Whites than African Americans (0.0627 vs. 0.2253, p=0.0020). Overall survival was, however, similar in both groups (15.8 vs. 14.3, p=0.7117).

Conclusion: A decreased psoas index in African American patients is associated with greater tumor size and an increased positive LNR. Notably, the most powerful outcome variable (LNR) did not correlate with psoas index in White patients even in the presence of increased nodal metastases. Most surprisingly, overall survival was similar in both patient groups. This suggests that a limited tumor burden does not provide a survival benefit for African Americans. We conclude that recognizing biologic variance among patients with ethnic diversity will allow better strategies to characterize metabolism, tumor microenvironment, and muscle architecture in PC. Together this will lead to improved overall survival.

Citation Format: Miles E. Cameron, Patrick W. Underwood, Michael H. Gerber, Steven J. Hughes, Andrew R. Judge, Jennifer B. Permuth, Jose G. Trevino. Key differences in muscular index and tumor burden reveal unique biology in ethnically diverse patients with pancreatic cancer [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr A106.

Abstract D106: Divergent biology in ethnically diverse populations is central to health disparities in pancreatic ductal adenocarcinoma

Introduction: Pancreatic ductal adenocarcinoma (PDAC) is a devastating diagnosis with a five-year survival rate below 9%. Among various ethnic groups there are differing incidence and mortality rates that underpin a patient’s overall prognosis. Blacks have higher incidence and mortality rates and a worse prognosis compared to Whites. Conversely, Hispanic/Latino patients have the lowest recorded incidence and mortality rates. Though well recognized by experts, these discrepancies are poorly understood and unaccounted for by socioeconomic means. Therefore, we hypothesize that divergent biology drives the observed disparities in PDAC. Methods: Patients with PDAC that underwent surgery at our institution between 2010 and 2017 were included in this retrospective study. Surgical pathology reports were reviewed, and cases were matched by age, gender, and tumor grade. Psoas muscle indices (PMI) were measured from pre-operative CT scans. Baseline indices for respective ethnic groups were determined from healthy patients with non-oncologic pathology. Whole-exome sequencing was then performed on DNA from tumor and adjacent benign parenchyma. Results: Healthy Blacks have a significantly greater PMI than case-matched Whites (0.90 vs. 0.70, p &lt; 0.005). Blacks and Whites with PDAC have a similar average pre-operative PMI (0.67 vs. 0.61, p = 0.3). However, when comparing pre-operative PMI to the baseline control PMI for the two racial groups, Blacks have a significantly greater percent decrease than Whites (29% vs. 14%, p &lt; 0.05). By whole-exome sequencing, 22 new somatic mutations were identified in Black tumor samples compared to 7 new mutations in Whites. Among mutations exclusively present Blacks, ABCF1 and ANAPC1 were reported to be associated with chemoresponse and survival in colorectal and lung adenocarcinomas, respectively. Cytochrome p450 family member CYP2A7 mutations were associated with peritoneal metastasis. PHACTR4 mutations were associated with Stat3 signaling activation and IL-6 mediated phosphorylation in hepatocellular carcinoma. Lastly, Hispanic/Latino patients, while not part of our tumor molecular sequencing, more frequently sought surgical intervention for pre-malignant cystic pancreatic neoplasms when compared to Whites (28% vs. 7%, p &lt; 0.05). Conclusion: Novel mutations and a strongly cachectic phenotype characterize Blacks with PDAC and may drive a particularly poor prognosis. While more research might define a molecular rationale for the better clinical outcomes in Latinos, Hispanic/Latino patients most frequently seek care for pre-malignant lesions. We conclude that recognizing the biological basis of cancer health disparities is essential for forming appropriate clinical decisions and defining specific therapeutic targets in ethnically diverse patients with PDAC.

Citation Format: Miles E Cameron, Patrick W Underwood, Michael U Maduka, Steven J Hughes, Andrea N Riner, Jennifer B Permuth, Andrew R Judge, Jose G Trevino. Divergent biology in ethnically diverse populations is central to health disparities in pancreatic ductal adenocarcinoma [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D106.

Abstract D110: Same patient, different tumor. Does heterogeneity of pancreatic cancer matter? Differences in growth rates of patient-derived xenografts from individual patients

Abstract Background Pancreatic cancer (PC) is one of the leading causes of cancer mortality and soon to be the second-leading cause of cancer death in the US by 2030. Patient derived xenografts (PDX) represent an opportunity to better understand the biology driving higher incidence and mortality. Racial disparities exist and Blacks have worse clinical outcomes than any other race. We hypothesize that the PDX tumors from the same patient will grow at differing rates including PDX development from patients of different races/ethnicities. Methods Under an IRB approved protocol, patients with the diagnosis of pancreatic adenocarcinoma (PDAC) were recruited for tissue donation. After surgical harvest of PC specimen, patient-derived xenograft (PDX) models were derived in NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mice. After initial passage from operation room, tumors from each individual patient were allowed to grow and subsequently divided and passed into 5 NSG mice and tumor growth rates were assessed by digital caliper. Patient race/ethnicity were de-identified as G and number of passages (p) from initial implantation were considered. Growth was assessed from 41 to 56 days. Coefficient of variation was attained and demonstrated the variability in growth values within each graft. Results PDX grafts (GXpX) were measured from 41 to 56 days. G1p5 and G2p1 were from non-Hispanic White patients and G3p3 was from a Black patient with PDAC. G1p5 grew an average of 0.25 mm per day and tumor size at 55 days after implantation were 1.0 cm, 1.4 cm, and 1.7 cm with a coefficient of variation of 20.98%. G2p1 grew an average of 0.17 mm per day and tumor sizes at 56 days were 0.7 cm and 1.3 cm with a coefficient of variation of 42.42%. G3p3 grew an average of 0.16 mm per day and tumor size at 41 days were 1.3 cm, 1.3 cm, and 0.7 cm with a coefficient of variation of 31.49%. The growth rate of mice implanted with patient tumor G2p1 demonstrated more growth variation than G3p3 and G1p5. Conclusion PDX from the same patient and different races exhibit differing growth rates over time. Each PDX should be considered as a unique tumor given its gross heterogeneity and possible genetic drift within the same tumor. Recommendations for PDX model use should include tumor measurements of each individual xenograft throughout time intervals throughout experiments especially when considering therapeutics. These important observations will leverage our understanding of much needed preclinical tumor models in PDAC and help improve our understanding of the biology of racial disparities in pancreatic cancer.

Citation Format: Michael U Maduka, Patrick W Underwood, Andrea N Riner, Miles E Cameron, Jose G Trevino. Same patient, different tumor. Does heterogeneity of pancreatic cancer matter? Differences in growth rates of patient-derived xenografts from individual patients [abstract]. In: Proceedings of the Twelfth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2019 Sep 20-23; San Francisco, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl_2):Abstract nr D110.

Disparities in Pancreatic Ductal Adenocarcinoma-The Significance of Hispanic Ethnicity, Subgroup Analysis, and Treatment Facility on Clinical Outcomes

Background

Disparities exist among patients with pancreatic ductal adenocarcinoma (PDAC). Non‐White race is regarded as a negative predictor of expected treatment and overall survival. Data suggest that Academic Research Programs (ARP) provide better outcomes for minorities, but ethnic/minority outcomes are underreported. We hypothesize that outcomes among racially/ethnically diverse PDAC patients may be influenced by treatment facility.

Methods

The National Cancer Database was used to identify 170,327 patients diagnosed with PDAC between 2004 and 2015. Cox proportional‐hazard regression was used to compare survival between race/ethnic groups across facilities.

Results

In unadjusted models, compared to non‐Hispanic Whites (NHW), non‐Hispanic Blacks (NHB) had the worst overall survival (HR = 1.05, 95%CI: 1.03‐1.06, P < .001) and Hispanics had the best overall survival (HR = 0.92, 95%CI: 0.90‐0.94, P < .001). After controlling for socioeconomic and clinical covariates, NHB (HR = 0.95, 95%CI: 0.93‐0.96, P < .001) had better overall survival compared to NHW, and Hispanics continued to have the best comparative outcomes (HR = 0.84, 95%CI: 0.82‐0.86, P < .001). Among Hispanics, Dominicans and South/Central Americans lived the longest, at 10.25 and 9.82 months, respectively. The improved survival in Hispanics was most pronounced at ARP (HR = 0.80, 95%CI: 0.77‐0.84, P < .001) and Integrated Network Cancer Programs (HR = 0.78, 95%CI: 0.73‐0.84, P < .001). NHB had improved survival over NHW at Comprehensive Community Care Programs (HR = 0.96, 95%CI: 0.93‐0.98, P = .002) and ARP (HR = 0.96, 95%CI: 0.94‐0.98, P = .001), which was influenced by income, education, and surgical resection.

Conclusion

Survival was improved at ARP for all populations. Hispanics had the best comparative overall survival. NHB had improved overall survival at higher volume centers, but this was dependent upon income, education, and surgical resection.

MEF2c-Dependent Downregulation of Myocilin Mediates Cancer-Induced Muscle Wasting and Associates with Cachexia in Patients with Cancer

Skeletal muscle wasting is a devastating consequence of cancer that contributes to increased complications and poor survival, but is not well understood at the molecular level. Herein, we investigated the role of Myocilin (Myoc), a skeletal muscle hypertrophy-promoting protein that we showed is downregulated in multiple mouse models of cancer cachexia. Loss of Myoc alone was sufficient to induce phenotypes identified in mouse models of cancer cachexia, including muscle fiber atrophy, sarcolemmal fragility, and impaired muscle regeneration. By 18 months of age, mice deficient in Myoc showed significant skeletal muscle remodeling, characterized by increased fat and collagen deposition compared with wild-type mice, thus also supporting Myoc as a regulator of muscle quality. In cancer cachexia models, maintaining skeletal muscle expression of Myoc significantly attenuated muscle loss, while mice lacking Myoc showed enhanced muscle wasting. Furthermore, we identified the myocyte enhancer factor 2 C (MEF2C) transcription factor as a key upstream activator of Myoc whose gain of function significantly deterred cancer-induced muscle wasting and dysfunction in a preclinical model of pancreatic ductal adenocarcinoma (PDAC). Finally, compared with noncancer control patients, MYOC was significantly reduced in skeletal muscle of patients with PDAC defined as cachectic and correlated with MEF2c. These data therefore identify disruptions in MEF2c-dependent transcription of Myoc as a novel mechanism of cancer-associated muscle wasting that is similarly disrupted in muscle of patients with cachectic cancer. SIGNIFICANCE: This work identifies a novel transcriptional mechanism that mediates skeletal muscle wasting in murine models of cancer cachexia that is disrupted in skeletal muscle of patients with cancer exhibiting cachexia.

Nicotine Induces IL-8 Secretion from Pancreatic Cancer Stroma and Worsens Cancer-Induced Cachexia

Smoking is highly associated with pancreatic cancer. Nicotine, the addictive component of tobacco, is involved in pancreatic cancer tumorigenesis, metastasis, and chemoresistance. This work aimed to describe the role of nicotine within the pancreatic cancer tumor microenvironment. Nicotine treatment was used in vitro to assess its effect on tumor-associated stromal cells and pancreatic cancer cells. Nicotine treatment was then used in a pancreatic cancer patient-derived xenograft model to study the effects in vivo. Nicotine induced secretion of interleukin 8 (IL-8) by tumor-associated stroma cells in an extracellular signal-regulated kinase (ERK)-dependent fashion. The secreted IL-8 and nicotine acted on the pancreatic cancer cell, resulting in upregulation of IL-8 receptor. Nicotine treatment of mice bearing pancreatic cancer patient-derived xenografts had significantly increased tumor mass, increased tumor-free weight loss, and decreased muscle mass. These represent important pathways through which nicotine acts within the tumor microenvironment and worsens pancreatic cancer-induced cachexia, potentially representing future therapeutic targets.

Protein Signatures and Tissue Diagnosis of Pancreatic Cancer

BACKGROUND

Endoscopic ultrasound-guided fine-needle aspiration fails to diagnose up to 25% of patients with pancreatic ductal adenocarcinoma (PDAC). Proteomics can help to overcome this clinical dilemma. We hypothesized that soluble protein signatures can differentiate PDAC from benign tissues.

STUDY DESIGN

Tissues were obtained from resected surgical specimens, lysed, and homogenates collected for analysis with a 41-protein multiplex assay. Analyte concentrations were normalized to total protein. Statistical analysis was performed to evaluate for differences in PDAC vs benign tissue.

RESULTS

Tissues were obtained from 159 patients, 82 patients with PDAC naïve to therapy and 77 with benign pancreatic pathology. Fourteen analytes had a receiver operating characteristic curve area of >0.75 for predicting PDAC vs benign tissue. A recursive partitioning model using only 2 analytes, interleukin 1 receptor antagonist and transforming growth factor-α, provided an accuracy, sensitivity, and specificity of 91.2%, 90.2%, and 92.2%, respectively. A penalized logistic regression model found 12 analytes that provide diagnostic value to a protein signature. The mean area under the receiver operating characteristic after 50 tenfold cross-validations was 0.951. Accuracy, sensitivity, and specificity of this model were 91.2%, 87.8%, and 94.8%, respectively. Applying the scenario of 80% disease prevalence in patients undergoing endoscopic ultrasound with fine-needle aspiration for a pancreatic head mass, positive predictive value is 98.5% (95% CI 93.0% to 99.7%) and negative predictive value is 66.0% (95% CI 54.9% to 75.6%).

CONCLUSIONS

Protein signatures from pancreatic specimens can differentiate PDAC from benign tissue. Additional work to validate these findings in a unique sample set is warranted.

The Proteome of Pancreatic Cancer-Derived Exosomes Reveals Signatures Rich in Key Signaling Pathways

Exosomes are membrane-bound vesicles that traffic small molecular cargos. These cargos participate in cell-cell communication and contribute to the pathogenesis of many disease including cancer. How these mechanisms contribute to communication within the pancreatic adenocarcinoma (PDAC) microenvironment and how they contribute to PDAC biology are poorly understood. Performed in this study are comprehensive, quantitative comparisons of the proteomes of three PDAC cell lines to those of the exosomes they produce. Approximately 35% of whole cell proteins sort into exosomes. Analysis of composition of microbiomes (ANCOM) determined a cluster of 98 enriched pancreatic cancer exosome core proteins (ePC-ECPs). Further, these proteins are predicted by ingenuity pathway analysis (IPA) as actively involved in signaling pathways regulating cell death and survival, cellular movement, and cell-to-cell signaling and interaction in particular (top three p-value significant pathways). Significant enrichment of canonical pathways of acute phase response signaling (inflammatory response signaling pathways) and FXR and RXR activation in biosynthetic pathways are also predicted; 97 ePC-ECPs are associated with cancer and among them, 34 are specifically associated with PDAC. In conclusion, exosomes from PDAC are enriched with cancer-associated signaling proteins. Further assessment of these proteins as PDAC biomarkers or therapeutic targets is warranted.

Abstract 4004: Unique patient signatures underlie health disparities in ethnically diverse patients with pancreatic cancer

Introduction: Health disparities in pancreatic cancer (PC) exist but how the underlying biology contributes to this is poorly described. Black Americans have a higher prevalence, present with more advanced disease, and suffer from higher mortality rates than other ethnic groups. Cancer cachexia, or cancer-associated muscle wasting, affects more than 80% of patients with PC. Unique muscular characteristics exist in different ethnic groups which might be contributing to pancreatic cancer health disparities. We hypothesize that Black patients with PC have a distinct muscular profile and are more affected by cancer cachexia than Whites and that unique genomic variations might contribute to this phenomenon in PC tumors between Black and White patients.

Methods: Black (including African Americans and Afro-Caribbeans) and non-Hispanic White surgically resected patients with PC between 2010 and 2017 were case matched by age, gender, and tumor grade. Muscular indices were measured from CT scans by dividing the area of the psoas muscles by the L3 vertebral body area to normalize for patient size. Whole-exome sequencing was performed on DNA from tumor and adjacent benign parenchyma.

Results: Healthy Blacks have a greater psoas index than Whites (0.8995 vs. 0.6988, p=0.004). When comparing patients with PC, Blacks and Whites were found to have similar psoas indices. Black patients had a greater percent decrease in psoas index than White patients (-25.29% vs. -12.37%, p=0.04). Tumor size inversely correlated to psoas index in Blacks (r=0.4330, p=0.007), but not in Whites (r=0.0025, p=0.9). Similar to tumor size, the positive lymph node ratio (LNR) inversely correlated to psoas index in Black patients (r=0.3930, p=0.01), but not in White patients (r=0.0867, p=0.2). LNR was significantly greater in Whites than Blacks (0.0627 vs. 0.2253, p=0.002), but overall survival was similar in both groups (15.8 vs. 14.3, p=0.7). In whole-exome sequencing, there were 22 mutations, of which several harbored implications in chemoresistance (ABCF1, ANAPC1), metastasis (CYP2A7, CYP21A2), and pathways of tumorigenesis (PHACTR4, PPP1R12B), and had 100% penetrance in Blacks but not in Whites. Seven mutations were present only in tumors of Whites but not Blacks.

Conclusion: Black Americans with PC suffer more muscle loss in the early stages of disease than Whites. A decreased psoas index in Black patients is associated with worse prognostic factors. In our genetic analysis, we identified 27 novel mutations not before reported in the literature. We conclude that recognizing biological variance in patients may underlie health disparities and allow investigations toward defining specific targets in a diverse group of patients with PC.

Citation Format: Miles E. Cameron, Patrick W. Underwood, Jinping Lai, Jennifer B. Permuth, Andrew R. Judge, Jose G. Trevino. Unique patient signatures underlie health disparities in ethnically diverse patients with pancreatic cancer [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 4004.

Dual Farnesyl and Geranylgeranyl Transferase Inhibitor Thwarts Mutant KRAS-Driven Patient-Derived Pancreatic Tumors

PURPOSE

Mutant KRAS is a major driver of pancreatic oncogenesis and therapy resistance, yet KRAS inhibitors are lacking in the clinic. KRAS requires farnesylation for membrane localization and cancer-causing activity prompting the development of farnesyltransferase inhibitors (FTIs) as anticancer agents. However, KRAS becomes geranylgeranylated and active when cancer cells are treated with FTIs. To overcome this geranylgeranylation-dependent resistance to FTIs, we designed FGTI-2734, a RAS C-terminal mimetic dual FT and geranylgeranyltransferase-1 inhibitor (GGTI).

EXPERIMENTAL DESIGN

Immunofluorescence, cellular fractionation, and gel shift assays were used to assess RAS membrane association, Western blotting to evaluate FGTI-2734 effects on signaling, and mouse models to demonstrate its antitumor activity.

RESULTS

FGTI-2734, but not the selective FTI-2148 and GGTI-2418, inhibited membrane localization of KRAS in pancreatic, lung, and colon human cancer cells. FGTI-2734 induced apoptosis and inhibited the growth in mice of mutant KRAS-dependent but not mutant KRAS-independent human tumors. Importantly, FGTI-2734 inhibited the growth of xenografts derived from four patients with pancreatic cancer with mutant KRAS (2 G12D and 2 G12V) tumors. FGTI-2734 was also highly effective at inhibiting, in three-dimensional cocultures with resistance promoting pancreatic stellate cells, the viability of primary and metastatic mutant KRAS tumor cells derived from eight patients with pancreatic cancer. Finally, FGTI-2734 suppressed oncogenic pathways mediated by AKT, mTOR, and cMYC while upregulating p53 and inducing apoptosis in patient-derived xenografts in vivo.

CONCLUSIONS

The development of this novel dual FGTI overcomes a major hurdle in KRAS resistance, thwarting growth of patient-derived mutant KRAS-driven xenografts from patients with pancreatic cancer, and as such it warrants further preclinical and clinical studies.

Pitfalls of minimally invasive pancreatoduodenectomy

Minimally invasive approaches to abdominal surgical procedures have provided superior outcomes when compared to the open approach and thus have become the standard of care. However, minimally invasive pancreatoduodenectomy (MIPD) presents unique difficulties for both laparoscopic and robotic platforms and remains controversial. Ongoing concerns continue about the minimally invasive approach creating meaningful benefit when system-wide data may suggest MIPD results in increased morbidity and mortality during the learning curve. This treatise explores the current state of MIPD, reviewing the volume and quality of data that supports benefit while contrasting the benefits to the unique challenges associated with MIPD that may lead to unacceptable rates of complications and death. We conclude that in a handful of centers, MIPD confers an iterative but not transformative benefit. Significant barriers to the wide-spread acceptance of MIPD are apparent and persist, including: lack of high level data confirming clinical benefit, well defined patient selection criteria, formal education programs that address challenges of the learning curve, and ultimately value.

Postoperative surgical trainee opioid prescribing practices (POST-OPP): A national survey

BACKGROUND

Increasing opioid-related deaths have heightened focus on combating the opioid epidemic. The impact of surgical trainees on opioid-related deaths is unclear, and there is little data examining the association between trainee pain management education and opioid prescribing practices.

METHODS

An anonymous, online survey was distributed to members of the Resident and Associate Society of the American College of Surgeons. The survey covered five themes: education and knowledge, prescribing practices, clinical case scenarios, policy, and beliefs and attitudes. Linear mixed models were used to evaluate the influence of respondent characteristics on reported morphine milligram equivalents (MME) prescribed for common general surgery clinical scenarios.

RESULTS

Of 427 respondents, 54 percent indicated receiving training in postoperative pain management during medical school and 66 percent during residency. Only 35 percent agreed that they had received adequate training in prescribing opioids. There was a significant association between undergoing formal pain management training in medical school and prescribing fewer MME for common outpatient general surgery scenarios (94 ± 15.2 vs 108 ± 15.0; p = 0.003). Similarly, formal pain management training in residency was associated with prescribing fewer MME in the survey scenarios (92.6 ± 15.2 vs 109 ± 15.2; p = 0.002).

CONCLUSION

In this survey, nearly two-thirds of surgical residents felt that they were inadequately trained in opioid pre-scribing. Our findings additionally suggest that improving education may result in increased resident comfort with man-aging surgical pain, potentially leading to more responsible opioid prescribing. Further work will facilitate residency pro-grams' development of educational curricula for opioid prescribing best practices.

Postoperative surgical trainee opioid prescribing practices (POST OPP): an institutional study

BACKGROUND

Increasing mortality from opioid overdoses has prompted increased focus on prescribing practices of physicians. Unfortunately, resident physicians rarely receive formal education in effective opioid prescribing practices or postoperative pain management. Data to inform surgical training programs regarding the utility and feasibility of formal training are lacking.

METHODS

Following Institutional Review Board approval, a single institution's resident physicians who had completed at least one surgical rotation were surveyed to assess knowledge of pain management and evaluate opioid prescribing practices.

RESULTS

Fifty-three respondents (68% males and 32% females) completed the survey. Most respondents denied receiving formal instruction in opioid pain medication prescribing practices during either medical school (62.3%) or residency (56.6%); however, nearly all respondents stated they were aware of the side effects of opioid pain medications, and a majority felt confident in their knowledge of opioid pharmacokinetics and pharmacodynamics. Of the respondents, 47% either "agreed" or "strongly agreed" that they prescribed more opioid medications than necessary to patients being discharged following a surgical procedure. Individual case scenario responses demonstrated variability in the number of morphine milligram equivalents prescribed across scenarios (P < 0.001). Male and nonsurgical specialty respondents reported prescribing significantly fewer overall morphine milligram equivalents in these scenarios.

CONCLUSIONS

This pilot study shows wide variability in opioid prescribing practices and attitudes toward pain management among surgical trainees, illustrating the potential utility of formal education in pain management and effective prescribing of these medications. A broader assessment of surgical trainees' knowledge and perception of opioid prescribing practices is warranted to facilitate the development of such a program.

Dorsal muscle group area and surgical outcomes in liver transplantation

INTRODUCTION

Better measures of liver transplant risk stratification are needed. Our previous work noted a strong relationship between psoas muscle area and survival following liver transplantation. The dorsal muscle group is easier to measure, but it is unclear if they are also correlated with surgical outcomes.

METHODS

Our study population included liver transplant recipients with a preoperative CT scan. Cross-sectional areas of the dorsal muscle group at the T12 vertebral level were measured. The primary outcomes for this study were one- and five-yr mortality and one-yr complications. The relationship between dorsal muscle group area and post-transplantation outcome was assessed using univariate and multivariate techniques.

RESULTS

Dorsal muscle group area measurements were strongly associated with psoas area (r = 0.72; p < 0.001). Postoperative outcome was observed from 325 patients. Multivariate logistic regression revealed dorsal muscle group area to be a significant predictor of one-yr mortality (odds ratio [OR] = 0.53, p = 0.001), five-yr mortality (OR = 0.53, p < 0.001), and one-yr complications (OR = 0.67, p = 0.007).

CONCLUSION

Larger dorsal muscle group muscle size is associated with improved post-transplantation outcomes. The muscle is easier to measure and may represent a clinically relevant postoperative risk factor.

Cigarette smoking in living kidney donors: donor and recipient outcomes

BACKGROUND

Living kidney donor pools are expanding with the use of "medically complex" donors. Whether or not to include cigarette smokers as living kidney donors remains unclear. The aim of this study was to determine the relationship between donor smoking and recipient outcomes. We hypothesized that donor smoking would increase donor complications and decrease allograft and recipient survival over time.

METHODS

The charts of 602 living kidney donors and their recipients were retrospectively reviewed. Kaplan-Meier survival analysis and Cox modeling were used to assess the relationships between smoking and recipient and allograft survival.

RESULTS

No difference in postoperative complications was seen in smoking versus non-smoking donors. Donor smoking at time of evaluation did not significantly decrease allograft survival (HR = 1.19, p = 0.52), but recipient smoking at evaluation did reduce allograft survival (HR = 1.74, p = 0.05). Both donor and recipient smoking decreased recipient survival (HR = 1.93, p < 0.01 vs HR = 1.74, p = 0.048).

DISCUSSION

When controlled for donor and recipient factors, cigarette smoking by living kidney donors significantly reduced recipient survival. This datum suggests that careful attention to smoking history is an important clinical measure in which to counsel potential donors and recipients. Policy efforts to limit donors with a recent smoking history should be balanced with the overall shortage of appropriate kidney donors.