Current and emerging therapies for the treatment of pancreatic cancer

Informal caregivers' experiences of supporting patients with pancreatic cancer: A qualitative study in Greece

PURPOSE

The purpose of the present study was to explore informal caregivers' experiences of supporting family members with pancreatic cancer.

METHODS

A qualitative descriptive study was conducted with individual semi-structured telephone interviews and inductive thematic analysis. Data were collected from 10 informal caregivers in the only cancer hospital in Northern Greece.

RESULTS

The findings of the thematic analysis highlighted three themes, "supportive needs of patients with pancreatic cancer", "supportive needs of informal caregivers" and "evaluation of provided care". In the first theme, four individual subcategories of themes emerged: "psychological support", "managing symptoms and side effects", "daily activities" and "participation in decision-making". The theme "supportive needs of informal caregivers" consists of five sub-themes, "psychological support", "support in care activities", "financial support", "communication with the patient" and "information". Finally, the theme "evaluation of provided care" three sub-categories of topics were reported, "staff evaluation", "process evaluation" and "palliative care".

CONCLUSION

Pancreatic cancer patients and their informal caregivers experience multiple unmet needs. The health system, lacking an efficient treatment for this type of cancer, should provide a basis for improving the quality of life of these families with targeted support interventions.

Development and validation of a competing risk model for second primary pancreatic ductal adenocarcinoma: A population-based study

Background

With advances in early diagnosis and treatment, the number of cancer survivors continues to grow, and more and more cancer survivors face the threat of second primary cancer (SPM). Second primary pancreatic ductal adenocarcinoma (spPDAC) is an important subclass of SPM, but its prognostic characteristics are poorly understood.

Methods

A total of 5,439 spPDAC samples and 67,262 primary pancreatic ductal adenocarcinoma (pPDAC) samples were extracted from the SEER database for this study. Survival differences between spPDAC and pPDAC samples were compared using Kaplan–Meier curves and log-rank tests. The Fine and Gray proportional subdistributed hazard method was used to analyze potential associations between clinical variables and pancreatic ductal adenocarcinoma-specific death (PDACSD) and death from other causes. After that, the clinical variables significantly related to PDACSD were screened out to construct a competing risk nomogram, which was used to evaluate the probability of the occurrence of PDACSD. The C-index was used to evaluate the discriminative ability of the model. The area under the curve (AUC) was used to verify the discrimination of the model. The calibration curve was used to verify the calibration of the model. Decision curve analysis (DCA) was used to validate the clinical utility of the model.

Results

Compared with patients with spPDAC, the pPDAC sample had a better prognosis (p = 0.0017). Across all spPDAC samples, the three most common sites of first-present cancer were the prostate, breast, and digestive system. Age (p < 0.001), race (p = 0.006), interval (p = 0.016), location (p < 0.001), T stage (p = 0.003), M stage (p < 0.001), chemotherapy (p < 0.001), and radiotherapy (p = 0.006) were the clinical variables associated with PDACSD screened by multivariate competing risks analysis. The concordance index values for the training and validation sets were 0.665 (95% CI, 0.655, 0.675) and 0.666 (95% CI, 0.650, 0.682), respectively. AUC, calibration curve, and DCA indicated that the model we constructed had good discrimination, calibration, and clinical utility.

Conclusions

In conclusion, we first analyzed the impact of previous cancer history on prognosis. We then constructed a competing risk model that can predict the probability of developing PDACSD in spPDAC. This model has good discriminative ability, calibration, and clinical practicability and has certain guiding value for clinical decision-making.

Impact of time interval between multidisciplinary team meeting and intended pancreatoduodenectomy on oncological outcomes

BACKGROUND

Dutch guidelines indicate that treatment of pancreatic head and periampullary malignancies should be started within 3 weeks of the multidisciplinary team (MDT) meeting. This study aimed to assess the impact of time to surgery on oncological outcomes.

METHODS

This was a retrospective population-based cohort study of patients with pancreatic head and periampullary malignancies included in the Netherlands Cancer Registry. Patients scheduled for pancreatoduodenectomy and who were discussed in an MDT meeting from May 2012 to December 2016 were eligible. Time to surgery was defined as days between the final preoperative MDT meeting and surgery, categorized in tertiles (short interval, 18 days or less; intermediate, 19-32 days; long, 33 days or more). Oncological outcomes included overall survival, resection rate and R0 resection rate.

RESULTS

A total of 2027 patients were included, of whom 677, 665 and 685 had a short, intermediate and long time interval to surgery respectively. Median time to surgery was 25 (i.q.r. 14-36) days. Longer time to surgery was not associated with overall survival (hazard ratio 0·99, 95 per cent c.i. 0·87 to 1·13; P = 0·929), resection rate (relative risk (RR) 0·96, 95 per cent c.i. 0·91 to 1·01; P = 0·091) or R0 resection rate (RR 1·01, 0·94 to 1·09; P = 0·733). Patients with pancreatic ductal adenocarcinoma and a long time interval had a lower resection rate (RR 0·92, 0·85 to 0·99; P = 0·029).

DISCUSSION

A longer time interval between the last MDT meeting and pancreatoduodenectomy did not decrease overall survival.

Effect of neoadjuvant radiotherapy on survival of non-metastatic pancreatic ductal adenocarcinoma: a SEER database analysis

BACKGROUND

Neoadjuvant radiotherapy has been shown to improve marginal negative resection and local control of Pancreatic Ductal Adenocarcinoma (PDAC). However, whether it improves overall survival (OS) in patients with non-metastatic PDAC remains controversial. Therefore, the purpose of this study was to analyze the benefits of only surgery, neoadjuvant radiotherapy, adjuvant radiotherapy, and surgery plus chemotherapy for OS in patients with non-metastatic PDAC.

METHODS

PDAC diagnosed by surgical histopathology in the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2016 was selected. Kaplan-Meier analysis was used to compare the prognosis of patients with different treatments. Cox proportional risk model was used to analyze independent predictors of OS. Propensity score matching (PSM) was used to analyze the tumor prognosis of different treatment methods.

RESULTS

Before PSM analysis, the OS of surgery plus chemotherapy (HRs = 0.896, 95%CIs, 0.827-0.970; P = 0.007) were significantly better than the other three treatments for stage T1-3N0M0 PDAC patients. For stage T1-3N + M0 patients, adjuvant radiotherapy (HRs = 0.613, 95% CIs, 0.579-0.649; P < 0.001) had significantly better OS than surgery plus chemotherapy and neoadjuvant radiotherapy. For stage T4N0M0 patients, neoadjuvant radiotherapy (HRs = 0.482, 95% CIs, 0.347-0.670; P < 0.001) had significantly better OS than surgery plus chemotherapy and adjuvant radiotherapy. For stage T4N + M0 patients, neoadjuvant radiotherapy (HRs = 0.338, 95% CIs, 0.215-0.532; P < 0.001) had significantly longer OS than adjuvant radiotherapy and surgery plus chemotherapy. Even after PSM, Chemotherapy plus surgery was still the best treatment for T1-3N0M0 patients. Postoperative adjuvant radiotherapy had the best prognosis among T1-3N + M0 patients, and neoadjuvant radiotherapy was the best treatment for T4 patients.

CONCLUSIONS

For patients with non-metastatic PDAC, neoadjuvant radiotherapy, adjuvant radiotherapy and surgery plus chemotherapy were superior to only surgery in OS. For patients with stage T4 non-metastatic PDAC, neoadjuvant radiotherapy had the potential to be strongly recommended over adjuvant radiotherapy and surgery plus chemotherapy. However, neoadjuvant radiotherapy failed to benefit the survival of T1-3N0M0 stage patients, and surgery plus chemotherapy was preferred. For T1-3N + M0, neoadjuvant radiotherapy had no obvious advantage over adjuvant radiotherapy or surgery plus chemotherapy in OS, and adjuvant radiotherapy was more recommended.

Postsurgical Outcome in Cats with Exocrine Pancreatic Carcinoma: Nine Cases (2007–2016)

Feline exocrine pancreatic carcinoma has been reported to be an aggressive tumor with a high metastatic rate and poor prognosis. Studies reporting long-term outcome of cats after surgical removal of solitary pancreatic carcinomas are rare, due to the uncommon diagnosis and paucity of cats who undergo treatment. In this study, nine cases of feline exocrine pancreatic carcinoma from seven academic and private practice veterinary hospitals were reviewed to examine the outcome in cats undergoing surgical removal of the mass. The median postsurgical survival time for the nine cats was 316.5 days (range, 25–964 days), with three cats alive at a median follow-up time of 309 days. This study demonstrates that surgical removal of pancreatic exocrine tumors in cats with localized disease can result in survival times of over 300 days.

The development of fluorescence guided surgery for pancreatic cancer: from bench to clinic

INTRODUCTION

Surgeons face major challenges in achieving curative R0 resection for pancreatic cancers. When the lesion is localized, they must appropriately visualize the tumor, determine appropriate resection margins, and ensure complete tumor clearance. Real-time surgical navigation using fluorescence-guidance has enhanced the ability of surgeons to see the tumor and has the potential to assist in achieving more oncologically complete resections. When there is metastatic disease, fluorescence enhancement can help detect these lesions and prevent unnecessary and futile surgeries. Areas covered: This article reviews different approaches for delivery of a fluorescence signal, their pre-clinical and clinical developments for fluorescence guided surgery, the advantages/challenges of each, and their potential for advancements in the future. Expert commentary: A variety of molecular imaging techniques are available for delivering tumor-specific fluorescence signals. Significant advancements have been made in the past 10 years due to the large body of literature on targeted therapies and this has translated into rapid developments of tumor-specific probes.

Depletion of pro-oncogenic RUNX2 enhances gemcitabine (GEM) sensitivity of p53-mutated pancreatic cancer Panc-1 cells through the induction of pro-apoptotic TAp63

Recently, we have described that siRNA-mediated silencing of runt-related transcription factor 2 (RUNX2) improves anti-cancer drug gemcitabine (GEM) sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells through the augmentation of p53 family TAp63-dependent cell death pathway. In this manuscript, we have extended our study to p53-mutated human pancreatic cancer Panc-1 cells. According to our present results, knockdown of mutant p53 alone had a marginal effect on GEM-mediated cell death of Panc-1 cells. We then sought to deplete RUNX2 using siRNA in Panc-1 cells and examined its effect on GEM sensitivity. Under our experimental conditions, RUNX2 knockdown caused a significant enhancement of GEM sensitivity of Panc-1 cells. Notably, GEM-mediated induction of TAp63 but not of TAp73 was further stimulated in RUNX2-depleted Panc-1 cells, indicating that, like AsPC-1 cells, TAp63 might play a pivotal role in the regulation of GEM sensitivity of Panc-1 cells. Consistent with this notion, forced expression of TAp63α in Panc-1 cells promoted cell cycle arrest and/or cell death, and massively increased luciferase activities driven by TAp63-target gene promoters such as p21^WAF1 and NOXA. In addition, immunoprecipitation experiments indicated that RUNX2 forms a complex with TAp63 in Panc-1 cells. Taken together, our current observations strongly suggest that depletion of RUNX2 enhances the cytotoxic effect of GEM on p53-mutated Panc-1 cells through the stimulation of TAp63-dependent cell death pathway even in the presence of a large amount of pro-oncogenic mutant p53, and might provide an attractive strategy to treat pancreatic cancer patients with p53 mutations.

Trichostatin A alters cytoskeleton and energy metabolism of pancreatic adenocarcinoma cells: An in depth proteomic study

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal of all human cancers with a high mortality rate. Resistance to conventional treatments and chemotherapeutics is a typical feature of PDAC. To investigate the causes of drug resistance it is essential to deeply investigate the mechanism of action of chemotherapeutics. In this study, we performed an in depth shotgun proteomic approach using the label-free proteomic SWATH-MS analysis to investigate novel insights of the mechanism of action of the histone deacetylase (HDAC) inhibitor trichostatin A (TSA) in PDAC cells. This proteomic analysis in PaCa44 cells and data elaboration of TSA-regulated proteins by bioinformatics showed an overall up-regulation of cytokeratins and other proteins related to the cytoskeleton organization, keratinization, and apoptotic cell death. On the contrary, a large amount of the down-regulated proteins by TSA treatment belongs to the cellular energetic metabolism and to the machinery of protein synthesis, such as ribosomal proteins, determining synergistic cell growth inhibition by the combined treatment of TSA and the glycolytic inhibitor 2-deoxy-d-glucose in a panel of PDAC cell lines. Data are available via ProteomeXchange with identifier PXD007801.

Irreversible Electroporation of the Pancreas Using Parallel Plate Electrodes in a Porcine Model: A Feasibility Study

BACKGROUND

Irreversible electroporation (IRE) with needle electrodes is being explored as treatment option in locally advanced pancreatic cancer. Several studies have shown promising results with IRE needles, positioned around the tumor to achieve tumor ablation. Disadvantages are the technical difficulties for needle placement, the time needed to achieve tumor ablation, the risk of needle track seeding and most important the possible occurrence of postoperative pancreatic fistula via the needle tracks. The aim of this experimental study was to evaluate the feasibility of a new IRE-technique using two parallel plate electrodes, in a porcine model.

METHODS

Twelve healthy pigs underwent laparotomy. The pancreas was mobilized to enable positioning of the paddles. A standard monophasic external cardiac defibrillator was used to perform an ablation in 3 separate parts of the pancreas; either a single application of 50 or 100J or a serial application of 4x50J. After 6 hours, pancreatectomy was performed for histology and pigs were terminated.

RESULTS

Histology showed necrosis of pancreatic parenchyma with neutrophil influx in 5/12, 11/12 and 12/12 of the ablated areas at 50, 100, and 4x50J respectively. The electric current density threshold to achieve necrosis was 4.3, 5.1 and 3.4 A/cm2 respectively. The ablation threshold was significantly lower for the serial compared to the single applications (p = 0.003). The content of the ablated areas differed between the applications: areas treated with a single application of 50 J often contained vital areas without obvious necrosis, whereas half of the sections treated with 100 J showed small islands of normal looking cells surrounded by necrosis, while all sections receiving 4x 50 J showed a homogeneous necrotic lesion.

CONCLUSION

Pancreatic tissue can be successfully ablated using two parallel paddles around the tissue. A serial application of 4x50J was most effective in creating a homogeneous necrotic lesion.

Silencing of RUNX2 enhances gemcitabine sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells through the stimulation of TAp63-mediated cell death

Runt-related transcription factor 2 (RUNX2) has been considered to be one of master regulators for osteoblast differentiation and bone formation. Recently, we have described that RUNX2 attenuates p53/TAp73-dependent cell death of human osteosarcoma U2OS cells bearing wild-type p53 in response to adriamycin. In this study, we have asked whether RUNX2 silencing could enhance gemcitabine (GEM) sensitivity of p53-deficient human pancreatic cancer AsPC-1 cells. Under our experimental conditions, GEM treatment increased the expression level of p53 family TAp63, whereas RUNX2 was reduced following GEM exposure, indicating that there exists an inverse relationship between the expression level of TAp63 and RUNX2 following GEM exposure. To assess whether TAp63 could be involved in the regulation of GEM sensitivity of AsPC-1 cells, small interfering RNA-mediated knockdown of TAp63 was performed. As expected, silencing of TAp63 significantly prohibited GEM-dependent cell death as compared with GEM-treated non-silencing cells. As TAp63 was negatively regulated by RUNX2, we sought to examine whether RUNX2 knockdown could enhance the sensitivity to GEM. Expression analysis demonstrated that depletion of RUNX2 apparently stimulates the expression of TAp63, as well as proteolytic cleavage of poly ADP ribose polymerase (PARP) after GEM exposure, and further augmented GEM-mediated induction of p53/TAp63-target genes, such as p21^WAF1, PUMA and NOXA, relative to GEM-treated control-transfected cells, implying that RUNX2 has a critical role in the regulation of GEM resistance through the downregulation of TAp63. Notably, ablation of TAp63 gave a decrease in number of γH2AX-positive cells in response to GEM relative to control-transfected cells following GEM exposure. Consistently, GEM-dependent phosphorylation of ataxia telangiectasia-mutated protein was remarkably impaired in TAp63 knockdown cells. Collectively, our present findings strongly suggest that RUNX2-mediated repression of TAp63 contributes at least in part to GEM resistance of AsPC-1 cells, and thus silencing of RUNX2 may be a novel strategy to enhance the efficacy of GEM in p53-deficient pancreatic cancer cells.

Cell death in response to antimetabolites directed at ribonucleotide reductase and thymidylate synthase

New agent development, mechanistic understanding, and combinatorial partnerships with known and novel modalities continue to be important in the study of pancreatic cancer and its improved treatment. In this study, known antimetabolite drugs such as gemcitabine (ribonucleotide reductase inhibitor) and 5-fluorouracil (thymidylate synthase inhibitor) were compared with novel members of these two drug families in the treatment of a chemoresistant pancreatic cancer cell line PANC-1. Cellular survival data, along with protein and messenger ribonucleic acid expression for survivin, XIAP, cIAP1, and cIAP2, were compared from both the cell cytoplasm and from exosomes after single modality treatment. While all antimetabolite drugs killed PANC-1 cells in a time- and dose-dependent manner, neither family significantly altered the cytosolic protein level of the four inhibitors of apoptosis (IAPs) investigated. Survivin, XIAP, cIAP1, and cIAP2 were found localized to exosomes where no significant difference in expression was recorded. This inability for significant and long-lasting expression may be a reason why pancreatic cancer lacks responsiveness to these and other cancer-killing agents. Continued investigation is required to determine the responsibilities of these IAPs in their role in chemoresistance in pancreatic adenocarcinoma.

A Novel CDC25B Promoter-Based Oncolytic Adenovirus Inhibited Growth of Orthotopic Human Pancreatic Tumors in Different Preclinical Models

PURPOSE

We decided to construct a novel oncolytic adenovirus whose replication was driven by the CDC25B promoter for its use in preclinical models of pancreatic cancer.

EXPERIMENTAL DESIGN

We placed the essential E1A gene under control of the CDC25B promoter. Based on preliminary data, we pseudotyped the adenovirus with a chimeric fiber of serotypes 5/3. We investigated the in vitro lytic effect and the in vivo therapeutic efficacy in combination with gemcitabine on human pancreatic tumor xenografts orthotopically growing in nude mice and in tumors growing in Syrian hamsters. We also assessed biochemical markers of hepatic toxicity and CA19.9 levels.

RESULTS

AV25CDC exhibited a strong in vitro lytic effect on pancreatic cancer cells. In vivo administration of AV25CDC combined with gemcitabine in mice harboring subcutaneously growing SW1990 pancreatic tumors almost abrogated tumor growth. Nude mice harboring 15-day-old orthotopic tumors, treated intratumorally or systemically with AV25CDC combined with gemcitabine, exhibited 70% to 80% reduction in tumor size compared with control mice that lasted for at least 60 days. Chemovirotherapy treatment induced a return to normal levels of biochemical parameters of hepatic toxicity; these mice exhibited more than 90% reduction in CA19.9 serum levels compared with control. Chemovirotherapy efficacy was confirmed in mice harboring Mia PaCa-2 tumors and in Syrian hamster harboring HaP-T1 tumors. We observed that viral treatment disrupted tumor architecture and induced an increase in MMP-9 activity that might facilitate gemcitabine penetrability.

CONCLUSION

These data demonstrate that AV25CDC is an effective oncolytic agent candidate for pancreatic cancer chemovirotherapy combination.

Radiofrequency ablation for unresectable locally advanced pancreatic cancer: a systematic review

BACKGROUND

Median survival in patients with unresectable locally advanced pancreatic cancer lies in the range of 9-15 months. Radiofrequency ablation (RFA) may prolong survival, but data on its safety and efficacy are scarce.

METHODS

A systematic literature search was performed in PubMed, EMBASE and the Cochrane Library with the syntax '(radiofrequency OR RFA) AND (pancreas OR pancreatic)' for studies published until 1 January 2012. In addition, a search of the proceedings of conferences on pancreatic disease that took place during 2009-2011 was performed. Studies with fewer than five patients were excluded as they were considered to be case reports. The primary endpoint was survival. Secondary endpoints included morbidity and mortality.

RESULTS

Five studies involving a total of 158 patients with pancreatic cancer treated with RFA fulfilled the eligibility criteria. These studies reported median survival after RFA of 3-33 months, morbidity related to RFA of 4-37%, mortality of 0-19% and overall morbidity of 10-43%. Pooling of data was not appropriate as the study populations and reported outcomes were heterogeneous. Crucial safety aspects included ensuring a maximum RFA tip temperature of < 90 °C and ensuring minimum distances between the RFA probe and surrounding structures.

CONCLUSIONS

Radiofrequency ablation seems to be feasible and safe when it is used with the correct temperature and at an appropriate distance from vital structures. It appears to have a positive impact on survival. Multicentre randomized trials are necessary to determine the true effect size of RFA and to minimize the impacts of selection and publication biases.

Antimetabolite Treatment for Pancreatic Cancer

Pancreatic cancer is a deadly and aggressive disease. Less than 1% of diagnosed patients survive 5 years with an average survival time of only 4–8 months. The only option for metastatic pancreatic cancer is chemotherapy where only the antimetabolites gemcitabine and 5-fluorouracil are used clinically. Unfortunately, efforts to improve chemotherapy regimens by combining, 5-fluorouracil or gemcitabine with other drugs, such as cisplatin or oxaliplatin, have not increased cell killing or improved patient survival. The novel antimetabolite zebularine shows promise, inducing apoptosis and arresting cellular growth in various pancreatic cancer cell lines. However, resistance to these antimetabolites remains a problem highlighting the need to discover and develop new antimetabolites that will improve a patient’s overall survival.

Radiofrequency ablation of the pancreas with and without intraluminal duodenal cooling in a porcine model

OBJECTIVE

To determine the short-term outcome of radiofrequency ablation (RFA) of pancreatic tissue near the duodenum and portomesenteric vessels (PMV) in a porcine model with and without intraluminal duodenal cooling.

BACKGROUND

RFA has been proposed as a new treatment strategy in patients with unresectable locally advanced pancreatic cancer. RFA may cause thermal damage to the duodenum and vascular structures, but these risks and potential protective measures have never been systematically addressed. Intraluminal duodenal cooling during RFA could prevent thermal damage to the duodenum.

METHODS

RFA was performed in 11 pigs during laparotomy with a bipolar probe of 30 mm active length at a power of 30 W until a total energy of 15 kJ was administered. The RFA probe was inserted in the pancreas at 5 or 15 mm from the duodenum, PMV, and in the pancreatic tail. RFA near the duodenum was performed with and without intraluminal duodenal cooling using 100 mL/min saline of 5°C. Histopathologic assessment was performed.

RESULTS

The maximum RFA-induced temperature was 92°C. RFA with one single probe induced adequate ablation lesions with a diameter of 20 mm over a length of 30 mm. Without duodenal cooling, RFA induced duodenal thermal damage, whereas with duodenal cooling, no damage was observed. RFA at 15 mm from the PMV resulted in minimal superficial focal vascular damage, without thrombosis or hemorrhage.

CONCLUSIONS

RFA provides adequate ablation zones in the pancreas of the porcine. Thermal damage to the duodenum can be prevented by intraluminal duodenal cooling without loss of ablation effectivity.

Transferrin receptor targeting nanomedicine delivering wild-type p53 gene sensitizes pancreatic cancer to gemcitabine therapy

To overcome gene therapy barriers such as low transfection efficiency and nonspecific delivery, liposomal nanoparticles targeted by a single-chain antibody fragment to the transferrin receptor (TfRscFv) delivering wild-type (wt) human p53 (SGT-53) were developed for tumor-specific targeting. We hypothesize that SGT-53 in combination with gemcitabine will demonstrate enhanced therapeutic benefit in an in vivo metastatic pancreatic cancer model. Intrasplenic injection of 1 × 10(6) Panc02 murine pancreatic cancer cells was used to generate in vivo hepatic metastatic tumors. Nanoparticle localization was assessed by tail vein injection of TfRscFv with fluorescently labeled oligonucleotides (6-carboxyfluorescein phosphoramidite (6FAM) ODN) imaged by Xenogen IVIS 200 scan. SGT-53 (equivalent to 30 μg of p53 intravenously) and gemcitabine (20 mg/kg intraperitoneally) alone and in combination were administered biweekly and compared with untreated mice. Survival was determined by blinded daily assessment of morbidity. Human wtp53 expression and transferrin levels in the tumors were assessed by western blot analysis. Tumor burden was quantified by liver weight. Xenogen imaging demonstrated tumor-specific uptake of TfRscFv-6FAM ODN. Exogenous human wtp53 protein was detected in the SGT-53-treated tumors compared with control. Compared with untreated mice with metastatic tumors demonstrating median survival of 20 days, SGT-53, gemcitabine and the combination demonstrated improved median survival of 29, 30 and 37 days, respectively. The combination treatment prolonged median survival when compared with single drug treatment and decreased tumor burden. The tumor targeting liposomal-based SGT-53 nanoparticle is capable of sensitizing pancreatic cancer to conventional chemotherapy in pancreatic cancer models. This approach has the potential to be translated into a new, more effective therapy for pancreatic cancer. Further optimization is ongoing, moving towards a Phase 1B/2 clinical trial.

Cytokine-induced killer cell therapy for advanced pancreatic adenocarcinoma: A case report and review of the literature

Patients with advanced pancreatic adenocarcinoma have a poor prognosis, and to date, no treatment method has had a significant impact on the disease. In general, the mean overall survival time of such patients receiving conventional chemotherapy and radiotherapy is <6 months. In the present case report, a patient with advanced pancreatic adenocarcinoma experienced a longer progression-free survival (PFS) of >19 months, following cytokine-induced killer (CIK) cell therapy. To the best of our knowledge, no study has previously described such a beneficial effect on patients only receiving CIK cell immunotherapy. Based on these findings, CIK cell therapy may be a potential treatment regimen that is capable of leading to an improved prognosis in certain patients with advanced pancreatic adenocarcinoma.

In vivo gene transfer targeting in pancreatic adenocarcinoma with cell surface antigens

BACKGROUND

Pancreatic ductal adenocarcinoma is a deadly malignancy resistant to current therapies. It is critical to test new strategies, including tumor-targeted delivery of therapeutic agents. This study tested the possibility to target the transfer of a suicide gene in tumor cells using an oncotropic lentiviral vector.

RESULTS

Three cell surface markers were evaluated to target the transduction of cells by lentiviruses pseudotyped with a modified glycoprotein from Sindbis virus. Only Mucin-4 and the Claudin-18 proteins were found efficient for targeted lentivirus transductions in vitro. In subcutaneous xenografts of human pancreatic cancer cells models, Claudin-18 failed to achieve efficient gene transfer but Mucin-4 was found very potent. Human pancreatic tumor cells were modified to express a fluorescent protein detectable in live animals by bioimaging, to perform a direct non invasive and costless follow up of the tumor growth. Targeted gene transfer of a bicistronic transgene bearing a luciferase gene and the herpes simplex virus thymidine kinase gene into orthotopic grafts was carried out with Mucin-4 oncotropic lentiviruses. By contrast to the broad tropism VSV-G carrying lentivirus, this oncotropic lentivirus was found to transduce specifically tumor cells, sparing normal pancreatic cells in vivo. Transduced cells disappeared after ganciclovir treatment while the orthotopic tumor growth was slowed down.

CONCLUSION

This work considered for the first time three aspect of pancreatic adenocarcinoma targeted therapy. First, lentiviral transduction of human pancreatic tumor cells was possible when cells were grafted orthotopically. Second, we used a system targeting the tumor cells with cell surface antigens and sparing the normal cells. Finally, the TK/GCV anticancer system showed promising results in vivo. Importantly, the approach presented here appeared to be a safer, much more specific and an as efficient way to perform gene delivery in pancreatic tumors, in comparison with a broad tropism lentivirus. This study will be useful in future designing of targeted therapies for pancreatic cancer.

Nationwide improvement of only short-term survival after resection for pancreatic cancer in the Netherlands

OBJECTIVES

Evaluation of incidence, treatment, and survival trends after resection of pancreatic cancer at a national level.

METHODS

Using data on patient and tumor characteristics from the nationwide Netherlands Cancer Registry trends were analyzed for the period 1989-2008.

RESULTS

A total of 30,025 patients diagnosed with pancreatic cancer were included. The incidence remained stable over the 20-year study period at approximately 9 per 100,000 inhabitants. Resection rates increased from 8% in 1989 to 12% in 2008, adjuvant chemotherapy rates increased from 7% to 29%, and palliative chemotherapy rates increased from 5% to 19% (P < 0.0001 each). Relative survival proportions did not change over time; besides a minimal, nonsignificant increase at 3 months from 53% to 55%, these remained 34% at 6 months and 4.5% at 3 years. Among the patients undergoing tumor resection, relative survival increased from 82% to 93% at 3 months and from 51% to 63% at 1 year after diagnosis. However, no improvement was seen after 3 years (23%).

CONCLUSIONS

The increased short-term survival among patients who underwent resection probably reflects decreased postoperative mortality driven by ongoing centralization efforts. However, longer-term survival remained poor irrespective of the changes in management in the past decades.

A 1536-well quantitative high-throughput screen to identify compounds targeting cancer stem cells

Tumor cell subpopulations called cancer stem cells (CSCs) or tumor-initiating cells (TICs) have self-renewal potential and are thought to drive metastasis and tumor formation. Data suggest that these cells are resistant to current chemotherapy and radiation therapy treatments, leading to cancer recurrence. Therefore, finding new drugs and/or drug combinations that cause death of both the differentiated tumor cells as well as CSC populations is a critical unmet medical need. Here, we describe how cancer-derived CSCs are generated from cancer cell lines using stem cell growth media and nonadherent conditions in quantities that enable high-throughput screening (HTS). A cell growth assay in a 1536-well microplate format was developed with these CSCs and used to screen a focused collection of oncology drugs and clinical candidates to find compounds that are cytotoxic against these highly aggressive cells. A hit selection process that included potency and efficacy measurements during the primary screen allowed us to efficiently identify compounds with potent cytotoxic effects against spheroid-derived CSCs. Overall, this research demonstrates one of the first miniaturized HTS assays using CSCs. The procedures described here should enable further testing of the effect of compounds on CSCs and help determine which pathways need to be targeted to kill them.

Microencapsulated tumor assay: evaluation of the nude mouse model of pancreatic cancer

AIM

To establish a more stable and accurate nude mouse model of pancreatic cancer using cancer cell microencapsulation.

METHODS

The assay is based on microencapsulation technology, wherein human tumor cells are encapsulated in small microcapsules (approximately 420 μm in diameter) constructed of semipermeable membranes. We implemented two kinds of subcutaneous implantation models in nude mice using the injection of single tumor cells and encapsulated pancreatic tumor cells. The size of subcutaneously implanted tumors was observed on a weekly basis using two methods, and growth curves were generated from these data. The growth and metastasis of orthotopically injected single tumor cells and encapsulated pancreatic tumor cells were evaluated at four and eight weeks postimplantation by positron emission tomography-computed tomography scan and necropsy. The pancreatic tumor samples obtained from each method were then sent for pathological examination. We evaluated differences in the rates of tumor incidence and the presence of metastasis and variations in tumor volume and tumor weight in the cancer microcapsules vs single-cell suspensions.

RESULTS

Sequential in vitro observations of the microcapsules showed that the cancer cells in microcapsules proliferated well and formed spheroids at days 4 to 6. Further in vitro culture resulted in bursting of the membrane of the microcapsules and cells deviated outward and continued to grow in flasks. The optimum injection time was found to be 5 d after tumor encapsulation. In the subcutaneous implantation model, there were no significant differences in terms of tumor volume between the encapsulated pancreatic tumor cells and cells alone and rate of tumor incidence. There was a significant difference in the rate of successful implantation between the cancer cell microencapsulation group and the single tumor-cell suspension group (100% vs 71.43%, respectively, P = 0.0489) in the orthotropic implantation model. The former method displayed an obvious advantage in tumor mass (4th wk: 0.0461 ± 0.0399 vs 0.0313 ± 0.021, t = -0.81, P = 0.4379; 8th wk: 0.1284 ± 0.0284 vs 0.0943 ± 0.0571, t = -2.28, respectively, P = 0.0457) compared with the latter in the orthotopic implantation model.

CONCLUSION

Encapsulation of pancreatic tumor cells is a reliable method for establishing a pancreatic tumor animal model.

Novel immunocompetent murine models representing advanced local and metastatic pancreatic cancer

BACKGROUND

The development of novel therapeutics for pancreatic cancer has been hindered by a lack of relevant preclinical models. The purpose of this study was to evaluate the clinical relevancy of two pancreatic cancer models using standard-of-care therapeutic agent gemcitabine.

MATERIALS AND METHODS

Murine Panc02 cells were injected directly into the spleen or pancreas of C57BL/6 mice to respectively create models of metastatic and locally advanced pancreatic cancer. Beginning 7 d post-Panc02 injection, treated mice received 20 mg/kg gemcitabine i.p. every 3 d. Animals were sacrificed when the untreated mice became moribund and tumor/liver weight used to assess tumor burden.

RESULTS

Untreated mice became moribund 22 d after pancreatic Panc02 injection. Gross analysis revealed localized pancreatic tumors weighing 1.063 g. Intrasplenic Panc02 injection produced extensive liver metastasis by d 15 when the untreated mice first became moribund. Liver weights at this time averaged 3.6 g compared with the average non-tumor-bearing weight of 1.23 g. Gemcitabine therapy resulted in a 54% decrease in localized pancreatic tumor weight and 62.5% decrease in metastatic liver weight. Additionally, gemcitabine therapy extended animal survival to 20.5 d compared with 18.0 d average for the untreated mice.

CONCLUSIONS

We describe two models depicting both locally advanced and metastatic pancreatic cancer in immunocompetent mice. In efforts to establish baseline therapeutic efficacy, we determined that gemcitabine reduces tumor burden in both models and enhances survival in the metastatic model. These clinically relevant models provide valuable tools to evaluate novel therapeutics in pancreatic cancer.

Molecular determinants of retinoic acid sensitivity in pancreatic cancer

PURPOSE

To identify a predictive molecular "signature" for sensitivity to retinoic acid in pancreatic cancer.

EXPERIMENTAL DESIGN

Fourteen patient-derived, low-passage pancreatic ductal adenocarcinoma (PDAC) lines with varied expression of fatty acid-binding protein 5 (FABP5) and cellular retinoic acid-binding protein 2 (CRABP2) were used to evaluate the response to all-trans retinoic acid (ATRA). Cell proliferation, apoptosis, and migration/invasion assays were used to measure the in vitro response. Tumor growth was monitored in subcutaneous xenografts in athymic nude mice for 4 weeks.

RESULTS

Response to ATRA was observed to be dependent upon differential expression of FABP5 versus CRABP2. Thus, elevated FABP5 expression was associated with minimal cytotoxicity and tumor growth inhibition and a paradoxical increase in migration and invasion. Conversely, CRABP2 expression in the absence of FABP5 was associated with significant tumor growth inhibition with ATRA, even in gemcitabine-resistant tumors. The ATRA-resistant phenotype of FABP5(high)CRABP2(null) cells could be circumvented by ectopic expression of CRABP2. Alternatively, reexpression of endogenous CRABP2 could be enabled in FABP5(high)CRABP2(null) PDAC lines by exposure to decitabine and trichostatin A, thereby relieving epigenetic silencing of the CRABP2 gene promoter. Immunohistochemical staining for FABP5 in archival human tissue microarrays identifies a subset of cases (13 of 63, ~20%) which are negative for FABP5 expression and might be candidates for ATRA therapy.

CONCLUSIONS

The widely used agent ATRA deserves a "second look" in PDAC, but needs to be targeted to patient subsets with biopsy-proven FABP5-negative tumors, or be combined with a chromatin-modifying agent to reexpress endogenous CRABP2.

Increased expression of DNA repair genes in invasive human pancreatic cancer cells

OBJECTIVE

Pancreatic cancer was the fourth leading cause of cancer death in the United States in 2010. Recurrence of disease after resection occurs because of neoplastic cell survival. To better understand these highly aggressive cells, gene expression microarrays were performed.

METHODS

Using the established lines HPAC and PANC1 and a Matrigel assay, genome expression arrays were performed to analyze patterns between invasive and total cells.

RESULTS

Significant increases in the expression of genes related to DNA repair were observed. A number of the same genes also demonstrated an increase in expression when comparing bulk cells to a putative tumor-initiating cell (TIC) population. The TIC population was isolated using the spheroid technique, and compared with bulk cells, spheroid cells functionally repair breaks in DNA faster after challenge with the drug gemcitabine. Finally, using Oncomine, we observed a significant increase in DNA copy number of BRCA1 and RAD51 in tissue isolated from metastatic pancreatic cancer compared with tissue isolated from the primary site.

CONCLUSIONS

From these data, we conclude that the most invasive cells within a pancreatic tumor are able to thrive because of their increased genomic stability. These cells have also been linked to the TIC population in a tumor.

DNA repair: the culprit for tumor-initiating cell survival?

The existence of "tumor-initiating cells" (TICs) has been a topic of heated debate for the last few years within the field of cancer biology. Their continuous characterization in a variety of solid tumors has led to an abundance of evidence supporting their existence. TICs are believed to be responsible for resistance against conventional treatment regimes of chemotherapy and radiation, ultimately leading to metastasis and patient demise. This review summarizes DNA repair mechanism(s) and their role in the maintenance and regulation of stem cells. There is evidence supporting the hypothesis that TICs, similar to embryonic stem (ES) cells and hematopoietic stem cells (HSCs), display an increase in their ability to survive genotoxic stress and injury. Mechanistically, the ability of ES cells, HSCs and TICs to survive under stressful conditions can be attributed to an increase in the efficiency at which these cells undergo DNA repair. Furthermore, the data presented in this review summarize the results found by our lab and others demonstrating that TICs have an increase in their genomic stability, which can allow for TIC survival under conditions such as anticancer treatments, while the bulk population of tumor cells dies. We believe that these data will greatly impact the development and design of future therapies being engineered to target and eradicate this highly aggressive cancer cell population.