Prognostic and predictive markers in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma is characterized by a poor prognosis and a low median survival, despite improvements observed for many other solid tumours. Intensive research efforts have been undertaken during the last decades to discover new prognostic and treatment predictive biomarkers for pancreatic ductal adenocarcinoma. The mainstay of medical treatment for the disease has been the well-tolerated nucleoside analogue, gemcitabine. The only targeted agent currently used in pancreatic ductal adenocarcinoma patients is the epithelial growth factor receptor inhibitor erlotinib in combination with gemcitabine. Recently, treatment regimens such as a combination of fluorouracil-leucovorin-irinotecan-oxaliplatin (FOLFIRINOX) and the combination of nab-paclitaxel with gemcitabine have been introduced for metastatic pancreatic ductal adenocarcinoma. Although these treatment regimens significantly improve survival of patients, there are no good predictive biomarkers available that can be used to identify who would benefit most from them. Therefore, the search for predictive biomarkers that would facilitate personalization of chemotherapy is highly relevant.

Biomarkers for pancreatic cancer: promising new markers and options beyond CA 19-9

Pancreatic adenocarcinoma accounts for nearly 90-95% of exocrine malignant tumors of the pancreas. Traditionally, overexpressed proteins/epitopes such as CA 19-9, CA-50, CEA, and many others were being used as pancreatic cancer tumor markers. The main utility of these biomarkers was in the diagnosis of pancreatic cancer as well as to assess response to chemotherapy and to determine prognosis and to predict tumor recurrence. However, these markers had significant limitations such as lack of sensitivity, false-negative results in certain blood groups, as well as false-positive elevation in the presence of obstructive jaundice. To circumvent these limitations, an extraordinary amount of research is being performed to identify an accurate tumor marker or a panel of markers that could aid in the management of the pancreatic cancer. Although this research has identified a large number and different variety of biomarkers, few hold future promise as a preferred marker for pancreatic cancer. This review provides an insight into exciting new areas of pancreatic biomarker research such as salivary, pancreatic juice, and stool markers that can be used as a noninvasive test to identify pancreatic cancer. This manuscript also provides a discussion on newer biomarkers, the role of microRNAs, and pancreatic cancer proteomics, which have the potential to identify a preferred tumor marker for pancreatic adenocarcinoma. This review further elaborates on important genetic changes associated with the development and progression of pancreatic cancer that holds the key for the identification of a sensitive biomarker and which could also serve as a therapeutic target.

Pancreatic intraepithelial neoplasia and pancreatic tumorigenesis: of mice and men

CONTEXT

Pancreatic cancer has a poor prognosis with a 5-year survival of less than 5%. Early detection is at present the only way to improve this outlook. This review focuses on the recent advances in our understanding of pancreatic carcinogenesis, the scientific evidence for a multistaged tumor progression, and the role genetically engineered mouse models can play in recapitulating the natural course and biology of human disease.

OBJECTIVES

To illustrate the stepwise tumor progression of pancreatic cancer and genetic alterations within the different stages of progression and to review the findings made with genetically engineered mouse models concerning pancreatic carcinogenesis.

DATA SOURCES

A review of recent literature on pancreatic tumorigenesis and genetically engineered mouse models.

CONCLUSIONS

Pancreatic cancer develops through stepwise tumor progression in which preinvasive stages, called pancreatic intraepithelial neoplasia, precede invasive pancreatic cancer. Genetic alterations in oncogenes and tumor suppressor genes underlying pancreatic cancer are also found in pancreatic intraepithelial neoplasia. These mutations accumulate during progression through the consecutive stages of pancreatic intraepithelial neoplasia lesions. Also in genetically engineered mouse models of pancreatic ductal adenocarcinoma, tumorigenesis occurs through stepwise progression via consecutive mouse pancreatic intraepithelial neoplasia, and these models provide important tools for clinical applications. Nevertheless differences between mice and men still remain.

Determination of qualitative telomerase activity as an adjunct to the diagnosis of pancreatic adenocarcinoma by EUS-guided fine-needle aspiration

BACKGROUND

Telomerase activity is up-regulated in pancreatic cancer. Hence, measurement of telomerase activity in pancreatic needle-biopsy specimens could assist in establishing a positive diagnosis in specimens that are inadequate for cytology.

OBJECTIVE

To determine the sensitivity and specificity of telomerase activity for neoplasia in a series of EUS-guided fine-needle aspirate (EUS-FNA) biopsies of pancreatic mass lesions.

DESIGN

Prospective, consecutive, non-randomized cohort.

SETTING

Academic hospital, tertiary referral center.

PATIENTS

Seventy-one patients with a pancreatic mass diagnosed by cross-sectional imaging.

INTERVENTIONS

EUS-FNA of 52 solid and 18 cystic pancreatic lesions.

MAIN OUTCOME MEASUREMENTS

(1) Cytologic diagnosis; (2) tissue telomerase activity by semi-quantitative polymerase chain reaction; (3) patient demographics; (4) clinical outcomes.

RESULTS

Cytology results were positive for adenocarcinoma in 40 patients with a solid pancreatic mass; of these, telomerase activity was detected in 31. There were no telomerase false-positive results. Telomerase results were positive in 6 of the 7 patients (86%) who had negative cytology results and who eventually were found to have biopsy-proven adenocarcinoma. The sensitivity and specificity of telomerase activity for detecting pancreatic adenocarcinoma in solid masses was 79% (95% CI, 64%-89%) and 100% (95% CI, 55%-100%).

LIMITATIONS

Extremely high sensitivity and specificity of EUS-FNA cytology in solid lesions minimized the incremental benefit of telomerase.

CONCLUSIONS

Telomerase activity can be measured readily in specimens obtained at EUS-FNA and accurately predicts malignancy. Used in combination with cytology, telomerase increased the sensitivity from 85% to 98% while maintaining the specificity at 100%. Lesions with negative cytology result and positive telomerase activity should be evaluated aggressively to exclude malignancy.

Frequent deletions of tumor suppressor genes in pure pancreatic juice from patients with tumoral or nontumoral pancreatic diseases

BACKGROUND/AIMS

K-ras codon 12 mutation is the most frequent genetic alteration in pancreatic cancer. Sensitivity and specificity of K-ras are not high enough to detect all pancreatic cancers, especially at early stage. This study investigated whether detection of p16 and/or DPC4 deletions along with K-ras mutation in DNA samples could improve the definition of patients at risk of pancreatic cancer.

METHODS

K-ras mutations were investigated by sequencing. p16 and DPC4 homozygous deletions were studied using comparative multiplex polymerase chain reaction of DNA in pancreatic juice sampled during endoscopic retrograde pancreatography in 57 patients with either pancreatic cancer (group I, 18 patients), chronic pancreatitis (group II, 20 patients), or nontumoral pancreatobiliary disease (group III, 19 patients).

RESULTS

The frequencies of Ki-ras mutations were 61% in group I, 10% in group II, and 10.5% in group III. The frequencies of p16 exon 2 and DPC4 deletions were, respectively, 28 and 36% in group I, 50 and 58% in group II, and 24 and 36% in group III.

CONCLUSIONS

The combination of p16 and DPC4 deletions with K-ras mutation does not improve the diagnosis of pancreatic cancer based on K-ras mutation alone. These data suggest that tumor suppressor gene inactivation can occur with a high frequency during nonmalignant pancreatic diseases.