Faculty Bibliography

Adenocarcinoma of the pancreas is a lethal malignancy, and better models to study tumor behavior in vivo are needed for the development ofmore effective therapeutics. Ionizing radiation is a treatment modality that is commonly used in the clinical setting, in particular, for locally confined disease; however, good model systems to study the effect of ionizing radiation in orthotopic tumors have not been established. In an attempt to create clinically relevant models for studying treatments directed against pancreatic cancer, we have defined a methodology to measure the effect of varying doses of radiation in established human pancreatic cancer orthotopic xenografts using two different pancreatic cancer cell lines (Panc-1 and BXPC3) infected with a lentiviral vector expressing CMV promoter-driven luciferase to allow bioluminescence imaging of live animals in real time. Quantifiable photon emission from luciferase signaling in vivo correlated well with actual tumor growth. Bioluminescence imaging of the established pancreatic xenografts was used to direct delivery of radiation to the orthotopic tumors and minimize off-target adverse effects. Growth delay was observed with schedules in the range of 7.5 Gy in five fractions to 10 Gy in four fractions, whereas doses 3 Gy or higher produced toxic adverse effects. In conclusion, we describe a model in which the effects of ionizing radiation, alone or in combination with other therapeutics, in orthotopic xenografts, can be studied.

BACKGROUND AND AIMS: Cystic lesions of the pancreas are increasingly being recognized due to the widespread use of high resolution abdominal imaging. Since certain cyst types are precursors to invasive cancer, this situation presents an opportunity to intervene prior to malignant progression. Effective implementation of that strategy has been hampered by difficulties in clearly distinguishing cystic lesions with no malignant potential from those with malignant potential. Here we explored whether glycosylation variants on specific proteins in cyst fluid samples could serve as biomarkers to aid in this diagnosis. METHODS: We used a novel antibody-lectin sandwich microarray method to measure the protein expression and glycosylation of mucin (MUC)1, MUC5AC, MUC16, carcinoembryonic antigen, and other proteins implicated in pancreatic neoplasia in cyst fluid samples. Fifty-three cyst fluid samples were obtained from patients with mucinous cystic neoplasms (n=17), intraductal papillary mucinous neoplasms (n=15), serous cystadenomas (n=12), or pseudocysts (n=9), with confirmation of histologic diagnosis at surgical resection. RESULTS: The detection of a glycan variant on MUC5AC using the lectin wheat-germ agglutinin discriminated mucin-producing cystic tumors (mucinous cystic neoplasms+intraductal papillary mucinous neoplasms) from benign cystic lesions (serous cystadenomas+pseudocysts) with a 78% sensitivity at 80% specificity, and when used in combination with cyst fluid CA 19-9 gave a sensitivity of 87% at 86% specificity. These biomarkers performed better than cyst fluid carcinoembryonic antigen (37%/80% sensitivity/specificity). CONCLUSIONS: These results demonstrate the value of glycan variants for biomarker discovery and suggest that these biomarkers could greatly enhance the accuracy of differentiating pancreatic cystic tumors. Validation studies will be required to determine the clinical value of these markers.

Pancreatic adenocarcinoma (PDA) is a highly lethal and aggressive malignancy with high mortality rates. It is critical to evaluate novel therapeutic strategies and targets for the treatment of this disease. In this article, the authors describe the important areas of focus in pancreatic cancer research, recent advances in these areas, and novel approaches that have the potential to bring about positive patient outcomes in this lethal disease. This article also focuses on recent developments in identifying new, more sensitive, and more specific blood biomarkers with potential use in the early detection of PDA.

Pancreatic adenocarcinoma is one of the leading causes of cancer death, in part because of the inability of current diagnostic methods to reliably detect early-stage disease. We present the first assessment of the diagnostic accuracy of algorithms developed for pancreatic tissue classification using data from fiber optic probe-based bimodal optical spectroscopy, a real-time approach that would be compatible with minimally invasive diagnostic procedures for early cancer detection in the pancreas. A total of 96 fluorescence and 96 reflectance spectra are considered from 50 freshly excised tissue sites-including human pancreatic adenocarcinoma, chronic pancreatitis (inflammation), and normal tissues-on nine patients. Classification algorithms using linear discriminant analysis are developed to distinguish among tissues, and leave-one-out cross-validation is employed to assess the classifiers' performance. The spectral areas and ratios classifier (SpARC) algorithm employs a combination of reflectance and fluorescence data and has the best performance, with sensitivity, specificity, negative predictive value, and positive predictive value for correctly identifying adenocarcinoma being 85, 89, 92, and 80%, respectively.

BACKGROUND:The management of incidental pancreatic cysts is not well established because of lack of information on their natural history. International Consensus Guidelines advocate observation of asymptomatic patients with small lesions, despite limited data to support this approach. METHODS:To characterize clinical outcomes in a cohort of asymptomatic patients with incidental pancreatic cysts who underwent endoscopic ultrasound (EUS) evaluation+/-fine needle aspiration (FNA). RESULTS:Overall, 317 patients underwent EUS for evaluation of pancreatic cysts from 1995 to 2005. A total of 97/317 (31%) had asymptomatic, incidentally discovered pancreatic cysts; of 97 asymptomatic patients, 93 were contacted. Of these patients, 71/93 (76%) had lesions<3 cm and benign EUS features. All were followed without operative therapy. The mean follow-up was 44 months (range, 6-123). A total of 69/71 (97%) were alive and free of symptoms of pancreatic disease; 2 patients died of unrelated causes. Among these 71 patients with lesions<3 cm, FNA was performed in 33 patients and cytology was negative for malignant cells in all. Overall, 45/71 patients had either follow-up cross-sectional imaging or EUS. All of them had stable lesions. Surveillance studies were performed with a mean follow-up of 28 months (range, 4-120). The 22 patients with lesions >3 cm and/or concerning EUS features underwent resection. Pathologic analysis revealed that 2/22 patients had adenocarcinoma and that 60% had premalignant lesions. CONCLUSION/CONCLUSIONS:Endoscopic ultrasound is helpful in evaluation of patients with small incidental pancreatic cystic lesions. Asymptomatic cysts with benign radiographic and/or endosonographic features may safely be followed clinically and with serial imaging.

The immunogenic nature of cancer can be explored to distinguish pancreatic cancer from related non-cancer conditions. We describe a liquid-based microarray approach followed by statistical analysis and confirmation for discovery of auto-immune biomarkers for pancreatic cancer. Proteins from the Panc-1 pancreatic cancer cell line were fractionated using a 2-D liquid separation method into over 1052 fractions and spotted onto nitrocellulose coated glass slides. The slides were hybridized with 37 pancreatic cancer sera, 24 chronic pancreatitis sera and 23 normal sera to detect elevated levels of reactivity against the proteins in spotted fractions. The response data obtained from protein microarrays was first analyzed by Wilcoxon Rank-Sum Tests to generate two lists of fractions that positively responded to the cancer sera and showed p-values less than 0.02 in the pairwise comparison between cancer specimens and normal and chronic pancreatitis specimens. The top 3 fractions with the lowest correlations were combined in receiver operating characteristic analyses. The area-under-the-curve (AUC) values are 0.813 and 0.792 for cancer vs. normal and cancer vs. pancreatitis respectively. Outlier-Sum statistics were then applied to the microarray data to determine the existence of outliers exclusive in cancer sera. The selected fractions were identified by LC-MS/MS. We further confirmed the occurrence of outliers with three proteins among cancer samples in a confirmation experiment using a separate dataset of 165 serum samples containing 48 cancer sera and 117 non-cancer controls. Phosphoglycerate kinase 1 (PGK1) elicited greater reactivity in 20.9% (10 in 48) of the samples in the cancer group, while no outlier was present in the non-cancer groups.

While several aberrant signaling pathways have been attributed to the formation and progression of pancreatic cancer, there is mounting evidence for the increased role of the Hedgehog (Hh) pathway in multiple aspects of pancreatic tumor development. The Hh pathway is a signaling cascade that plays an important role in cell patterning of multiple tissues and organs, including the development of the gastrointestinal system. While normal pancreatic tissue exhibits little Hh pathway activity, patients with pancreatic adenocarcinoma show high levels of Hh pathway signaling in both the tumor epithelia and the surrounding mesenchyme. Several recent studies have focused on this paracrine activation of Hh signaling in the tumor microenvironment and have provided evidence for how activation of this pathway may play roles in mediating cellular proliferation, metastasis, and resistance to therapy. Together, these findings present new insights into how modulation of this pathway may allow us to target multiple aspects of pancreatic tumor biology.

PURPOSE/OBJECTIVE:To report outcomes for patients with resected pancreas cancer treated with an adjuvant regimen consisting of gemcitabine-based combination chemotherapy followed by capecitabine and radiation. PATIENTS AND METHODS/METHODS:We performed a retrospective review of a series of patients treated at a single institution with a common postoperative adjuvant program. Between January 2002 and August 2006, 43 resected pancreas cancer patients were offered treatment consisting of 4, 21-day cycles of gemcitabine 1 g/m(2) intravenously over 30 min on Days 1 and 8, with either cisplatin 35 mg/m(2) intravenously on Days 1 and 8 or capecitabine 1500 mg/m(2) orally in divided doses on Days 1-14. After completion of combination chemotherapy, patients received a course of radiotherapy (54 Gy) with concurrent capecitabine (1330 mg/m(2) orally in divided doses) day 1 to treatment completion. RESULTS:Forty-one patients were treated. Median progression-free survival for the entire group was 21.7 months (95% confidence interval 13.9-34.5 months), and median overall survival was 45.9 months. In multivariate analysis a postoperative CA 19-9 level of >or=180 U/mL predicted relapse and death. Toxicity was mild, with only two hospitalizations during adjuvant therapy. CONCLUSIONS:A postoperative adjuvant program using combination chemotherapy with gemcitabine and either cisplatin or capecitabine followed by radiotherapy with capecitabine is tolerable and efficacious and should be considered for Phase III testing in this group of patients.

Pancreatic ductal adenocarcinoma (PDAC) is the fourth leading cause of cancer mortality, despite significant improvements in diagnostic imaging and operative mortality rates. The 5-year survival rate remains less than 5% because of microscopic or gross metastatic disease at time of diagnosis. The Clinical Trials Planning Meeting in pancreatic cancer was convened by the National Cancer Institute's Gastrointestinal Cancer Steering Committee to discuss the integration of basic and clinical knowledge in the design of clinical trials in PDAC. Major emphasis was placed on the enhancement of research to identify and validate the relevant targets and molecular pathways in PDAC, cancer stem cells, and the microenvironment. Emphasis was also placed on developing rational combinations of targeted agents and the development of predictive biomarkers to assist selection of patient subsets. The development of preclinical tumor models that are better predictive of human PDAC must be supported with wider availability to the research community. Phase III clinical trials should be implemented only if there is a meaningful clinical signal of efficacy and safety in the phase II setting. The emphasis must therefore be on performing well-designed phase II studies with uniform sets of basic entry and evaluation criteria with survival as a primary endpoint. Patients with either metastatic or locally advanced PDAC must be studied separately.

An empirical model was developed to interpret differences in the experimentally measured reflectance and fluorescence spectra of freshly excised human pancreatic tissues: normal, adenocarcinoma, and pancreatitis (inflammation). The model provided the first quantitative links between spectroscopic measurements and histological characteristics in the human pancreas. The reflectance model enabled the first (to our knowledge) extraction of wavelength resolved absorption and reduced scattering coefficients for normal and diseased human pancreatic tissues. The fluorescence model employed reflectance information to extract attenuation free "intrinsic" endogenous fluorescence spectra from normal pancreatic tissue, pancreatic adenocarcinoma, and pancreatitis. The method developed is simple, intuitive, and potentially useful for a range of applications in optical tissue diagnostics. This approach is potentially applicable to in vivo studies, because it can account for the absorptive effects of blood in tissues.