Chemotherapy in advanced pancreatic adenocarcinoma

A composite smeared finite element for mass transport in capillary systems and biological tissue

One of the key processes in living organisms is mass transport occurring from blood vessels to tissues for supplying tissues with oxygen, nutrients, drugs, immune cells, and - in the reverse direction - transport of waste products of cell metabolism to blood vessels. The mass exchange from blood vessels to tissue and vice versa occurs through blood vessel walls. This vital process has been investigated experimentally over centuries, and also in the last decades by the use of computational methods. Due to geometrical and functional complexity and heterogeneity of capillary systems, it is however not feasible to model in silico individual capillaries (including transport through the walls and coupling to tissue) within whole organ models. Hence, there is a need for simplified and robust computational models that address mass transport in capillary-tissue systems. We here introduce a smeared modeling concept for gradient-driven mass transport and formulate a new composite smeared finite element (CSFE). The transport from capillary system is first smeared to continuous mass sources within tissue, under the assumption of uniform concentration within capillaries. Here, the fundamental relation between capillary surface area and volumetric fraction is derived as the basis for modeling transport through capillary walls. Further, we formulate the CSFE which relies on the transformation of the one-dimensional (1D) constitutive relations (for transport within capillaries) into the continuum form expressed by Darcy's and diffusion tensors. The introduced CSFE is composed of two volumetric parts - capillary and tissue domains, and has four nodal degrees of freedom (DOF): pressure and concentration for each of the two domains. The domains are coupled by connectivity elements at each node. The fictitious connectivity elements take into account the surface area of capillary walls which belongs to each node, as well as the wall material properties (permeability and partitioning). The overall FE model contains geometrical and material characteristics of the entire capillary-tissue system, with physiologically measurable parameters assigned to each FE node within the model. The smeared concept is implemented into our implicit-iterative FE scheme and into FE package PAK. The first three examples illustrate accuracy of the CSFE element, while the liver and pancreas models demonstrate robustness of the introduced methodology and its applicability to real physiological conditions.

Nanoparticle delivery of an AKT/PDK1 inhibitor improves the therapeutic effect in pancreatic cancer

The K-ras mutation in pancreatic cancer can inhibit drug delivery and increase drug resistance. This is exemplified by the therapeutic effect of PH-427, a small molecule inhibitor of AKT/PDK1, which has shown a good therapeutic effect against a BxPC3 pancreatic cancer model that has K-ras, but has a poor therapeutic effect against a MiaPaCa-2 pancreatic cancer model with mutant K-ras. To increase the therapeutic effect of PH-427 against the MiaPaCa-2 pancreatic cancer model with mutant K-ras, we encapsulated PH-427 into poly(lactic-co-glycolic acid) nanoparticles (PNP) to form drug-loaded PH-427-PNP. PH-427 showed a biphasic release from PH-427-PNP over 30 days during studies in sodium phosphate buffer, and in vitro studies revealed that the PNP was rapidly internalized into MiaPaCa-2 tumor cells, suggesting that PNP can improve PH-427 delivery into cells harboring mutant K-ras. In vivo studies of an orthotopic MiaPaCa-2 pancreatic cancer model showed reduced tumor load with PH-427-PNP as compared with treatment using PH-427 alone or with no treatment. Ex vivo studies confirmed the in vivo results, suggesting that PNP can improve drug delivery to pancreatic cancer harboring mutant K-ras.

Overexpression of COL11A1 by cancer-associated fibroblasts: clinical relevance of a stromal marker in pancreatic cancer

BACKGROUND

The collagen11A1 (COL11A1) gene is overexpressed in pancreatic cancer. The expression of COL11A1 protein could be involved in desmoplastic events in pancreatic cancer, but an antibody that specifically stains the COL11A1 protein is not currently available.

METHODS AND FINDINGS

A total of 54 pancreatic ductal adenocarcinomas (PDAC), 23 chronic pancreatitis (CP) samples, and cultured peritumoral stromal cells of PDAC (passages 3-6) were studied. Normal human pancreas tissue samples were obtained through a cadaveric organ donation program. 1) Validation of COL11A1 gene overexpression by q-RT-PCR.

FINDINGS

the expression of COL11A1 gene is significantly increased in PDAC samples vs. normal and CP samples. 2) Analysis of COL11A1 by immunohistochemistry using highly specific anti-proCOL11A1 antibodies.

FINDINGS

anti-proCOL11A1 stains stromal cells/cancer-associated fibroblasts (CAFs) of PDAC but it does not stain chronic benign condition (chronic pancreatitis) stromal cells, epithelial cells, or normal fibroblasts. 3) Evaluation of the discrimination ability of the antibody.

FINDINGS

anti-proCOL11A1 immunostaining accurately discriminates between PDAC and CP (AUC 0.936, 95% CI 0.851, 0.981). 4) Phenotypic characterization of proCOL11A1+ stromal cells co-staining with mesenchymal, epithelial and stellate cell markers on pancreatic tissue samples and cultured peritumoral pancreatic cancer stromal cells.

FINDINGS

ProCOL11A1+ cells present co-staining with mesenchymal, stellate and epithelial markers (EMT phenotype) in different proportions.

CONCLUSIONS/SIGNIFICANCE

Detection of proCOL11A1 through immunostaining with this newly-developed antibody allows for a highly accurate distinction between PDAC and CP. Unlike other available antibodies commonly used to detect CAFs, anti-proCOL11A1 is negative in stromal cells of the normal pancreas and almost absent in benign inflammation. These results strongly suggest that proCOL11A1 is a specific marker for CAFs, and thus, anti-proCOL11A1 is a powerful new tool for cancer research and clinical diagnostics.

Establishment and characterization of a new human pancreatic adenocarcinoma cell line with high metastatic potential to the lung

BACKGROUND

Pancreatic cancer is still associated with devastating prognosis. Real progress in treatment options has still not been achieved. Therefore new models are urgently needed to investigate this deadly disease. As a part of this process we have established and characterized a new human pancreatic cancer cell line.

METHODS

The newly established pancreatic cancer cell line PaCa 5061 was characterized for its morphology, growth rate, chromosomal analysis and mutational analysis of the K-ras, EGFR and p53 genes. Gene-amplification and RNA expression profiles were obtained using an Affymetrix microarray, and overexpression was validated by IHC analysis. Tumorigenicity and spontaneous metastasis formation of PaCa 5061 cells were analyzed in pfp-/-/rag2-/- mice. Sensitivity towards chemotherapy was analysed by MTT assay.

RESULTS

PaCa 5061 cells grew as an adhering monolayer with a doubling time ranging from 30 to 48 hours. M-FISH analyses showed a hypertriploid complex karyotype with multiple numerical and unbalanced structural aberrations. Numerous genes were overexpressed, some of which have previously been implicated in pancreatic adenocarcinoma (GATA6, IGFBP3, IGFBP6), while others were detected for the first time (MEMO1, RIOK3). Specifically highly overexpressed genes (fold change > 10) were identified as EGFR, MUC4, CEACAM1, CEACAM5 and CEACAM6. Subcutaneous transplantation of PaCa 5061 into pfp-/-/rag2-/- mice resulted in formation of primary tumors and spontaneous lung metastasis.

CONCLUSION

The established PaCa 5061 cell line and its injection into pfp-/-/rag2-/- mice can be used as a new model for studying various aspects of the biology of human pancreatic cancer and potential treatment approaches for the disease.

Gemcitabine-based chemogene therapy for pancreatic cancer using Ad-dCK::UMK GDEPT and TS/RR siRNA strategies

Gemcitabine is a first-line agent for advanced pancreatic cancer therapy. However, its efficacy is often limited by its poor intracellular metabolism and chemoresistance. To exert its antitumor activity, gemcitabine requires to be converted to its active triphosphate form. Thus, our aim was to improve gemcitabine activation using gene-directed enzyme prodrug therapy based on gemcitabine association with the deoxycytidine kinase::uridine monophosphate kinase fusion gene (dCK::UMK) and small interference RNA directed against ribonucleotide reductase (RRM2) and thymidylate synthase (TS). In vitro, cytotoxicity was assessed by 3-[4,5-dimethylthiazol-2-yl]-3,5-diphenyl tetrazolium bromide and [(3)H]thymidine assays. Apoptosis-related gene expression and activity were analyzed by reverse transcription-polymerase chain reaction, Western blot, and ELISA. For in vivo studies, the treatment efficacy was evaluated on subcutaneous and orthotopic pancreatic tumor models. Our data indicated that cell exposure to gemcitabine induced a down-regulation of dCK expression and up-regulation of TS and RR expression in Panc1-resistant cells when compared with BxPc3- and HA-hpc2-sensitive cells. The combination of TS/RRM2 small interference RNA with Ad-dCK::UMK induced a 40-fold decrease of gemcitabine IC(50) in Panc1 cells. This strong sensitization was associated to apoptosis induction with a remarkable increase in TRAIL expression and a diminution of gemcitabine-induced nuclear factor-kappaB activity. In vivo, the gemcitabine-based tritherapy strongly reduced tumor volumes and significantly prolonged mice survival. Moreover, we observed an obvious increase of apoptosis and decrease of cell proliferation in tumors receiving the tritherapy regimens. Together, these findings suggest that simultaneous TS/RRM2-gene silencing and dCK::UMK gene overexpression markedly improved gemcitabine's therapeutic activity. Clearly, this combined strategy warrants further investigation.

Regulation of pancreatic tumor cell proliferation and chemoresistance by the histone methyltransferase enhancer of zeste homologue 2

PURPOSE

Enhancer of zeste homologue 2 (EZH2), a histone methyltransferase, plays a key role in transcriptional repression through chromatin remodeling. Our objectives were to determine the expression pattern of EZH2 and to assess the anticancer effect of EZH2 depletion in pancreatic cancer cells.

EXPERIMENTAL DESIGN

Immunohistochemistry and cytosolic/nuclear fractionation were done to determine the expression pattern of EZH2 in normal pancreas and human pancreatic tumors. We used RNA interference, Western blotting, reverse transcription-PCR, and chromatin immunoprecipitation to study the effect of EZH2 depletion on pancreatic cancer cell proliferation and survival.

RESULTS

We detected nuclear overexpression of EZH2 in pancreatic cancer cell lines and in 71 of 104 (68%) cases of human pancreatic adenocarcinomas. EZH2 nuclear accumulation was more frequent in poorly differentiated pancreatic adenocarcinomas (31 of 34 cases; P<0.001). We found that genetic depletion of EZH2 results in reexpression of p27(Kip1) and decreased pancreatic cancer cell proliferation. Moreover, we showed that EZH2 depletion sensitized pancreatic cancer cells to doxorubicin and gemcitabine, which leads to a significant induction of apoptosis, suggesting that the combination of EZH2 inhibitors and standard chemotherapy could be a superior potential treatment for pancreatic cancer.

CONCLUSIONS

Our results show nuclear accumulation of EZH2 as a hallmark of poorly differentiated pancreatic adenocarcinoma; identify the tumor suppressor p27(Kip1) as a new target gene of EZH2; show that EZH2 nuclear overexpression contributes to pancreatic cancer cell proliferation; and suggest EZH2 as a potential therapeutic target for the treatment of pancreatic cancer.

New target therapies in advanced pancreatic cancer

The recent elucidation both of the mechanisms involved in pancreatic cancer carcinogenesis and the related molecular events, has led to several distinct therapeutic advances, including many novel target agents, such as monoclonal antibodies against EGFR, EGFR-tyrosine kinase inhibitors, monoclonal antibody against VEGF, farnesyl transferase inhibitors, matrix metalloproteinase inhibitors, COX 2 inhibitors, and the development of gene therapy to target pancreatic cancer. This review highlights recent findings in the treatment of pancreatic cancer by using these novel therapeutic approaches.

Gemcitabine plus CI-994 offers no advantage over gemcitabine alone in the treatment of patients with advanced pancreatic cancer: results of a phase II randomized, double-blind, placebo-controlled, multicenter study

BACKGROUND

CI-994, an oral histone deacetylase inhibitor, has antineoplastic activity and synergism with gemcitabine preclinically. This randomized phase II trial explored whether CI-994 plus gemcitabine improves overall survival, objective response, duration of response, time to treatment failure and change in quality of life (QoL) or pain compared with gemcitabine alone.

PATIENTS AND METHODS

A total of 174 patients received CG (CI-994 6 mg/m(2)/day days 1-21 plus gemcitabine 1000 mg/m(2) days 1, 8 and 15 each 28-day cycle) or PG (placebo plus gemcitabine 1000 mg/m(2) days 1, 8 and 15 of each 28-day cycle days 1-21).

RESULTS

Median survival was 194 days (CG) versus 214 days (PG) (P = 0.908). The objective response rate with CG was 12% versus 14% with PG when investigator-assessed and 1% versus 6%, respectively, when assessed centrally. Time to treatment failure did not differ between the two arms (P = 0.304). QoL scores at 2 months were worse with CG than with PG. Pain response rates were similar between the two groups. There was an increased incidence of neutropenia and thrombocytopenia with CG.

CONCLUSIONS

Adding CI-994 to gemcitabine in advanced pancreatic carcinoma does not improve overall survival, response rate or time to progression; CG produced decreased QoL and increased hematological toxicity and appears inferior to single-agent gemcitabine.

A structurally optimized celecoxib derivative inhibits human pancreatic cancer cell growth

Deregulation of the phosphatidylinositol 3-kinase (PI-3K)/PDK-l/Akt signaling cascade is associated with pancreatic cancer tumor invasion, angiogenesis, and tumor progression. As such, it has been postulated that PDK-1/Akt signaling inhibitors may hold promise as novel therapeutic agents for pancreatic cancer. Disadvantages of currently available Akt inhibitors include tumor resistance, poor specificity, potential toxicity, and poor bioavailability. Previous studies have demonstrated that OSU-03012, a celecoxib derivative, specifically inhibits PDK-1 mediated phosphorylation of Akt with IC(50) values in the low muM range. Human pancreatic cancer cell lines AsPC-1, BxPC-3, Mia-PaCa 2, and PANC-1 were cultured in media containing varying concentrations of OSU-03012, 5-fluorouracil (5-FU), and gemcitabine, and changes in Akt phosphorylation and cell viability were evaluated using western blotting and a 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, respectively. Treatment with OSU-03012 resulted in decreased PDK-1-mediated Akt phosphorylation and cell growth inhibition for all cell lines with IC(50) values ranging between 1.0 and 2.5 muM. Resistance to 5-FU and gemcitabine was observed in cell lines AsPC-1 and BxPC-3. Further analyses indicate that OSU-03012 induces both proapoptotic and antiproliferative effects in these cells. Taken together, these data suggest that OSU-03012 has potential value as a novel therapy for pancreatic cancer.

Phase II trial of a 24-hour infusion of gemcitabine in previously untreated patients with advanced pancreatic adenocarcinoma

The antitumor effect of gemcitabine is not dose-response related but schedule dependent. Here we report a phase II trial of a weekly 24-hour infusion of gemcitabine in previously untreated patients with advanced pancreatic cancer. Patients with histologically proven, measurable, and irresectable pancreatic adenocarcinoma were treated with gemcitabine at a dose of 100 mg/m2 infused over 24 hr on days 1, 8, and 15. Treatment was repeated every 28 days until progression of disease or limiting toxicity. All 18 patients enrolled were evaluable for response. Neutropenia and thrombocytopenia grade 3 occurred in 1 patient each. One partial response and two minor responses were observed. Median time to progression of disease was 4.4 months. Improvement of the European Organization for Research and Treatment of Cancer C30 scores was observed in 6 patients (pain and overall symptom score, respectively) and in 3 patients (overall functioning score and global quality of life, respectively). Weekly 24-hr gemcitabine was well tolerated in previously untreated patients with advanced pancreatic cancer. It shows marginal antitumor activity in terms of response rate. However, the 24-hr infusion at a dose of 100 mg/m2 seems to be as active as the standard 30-min gemcitabine at a dose of 1000 mg/m2. Relatively long median time to progression of disease and improvement of symptom and quality-of-life scores suggest, that patients may benefit from 24-hr gemcitabine.

The medical management of pancreatic cancer: a review

Pancreatic carcinoma is a commonly occurring cancer that tends to present late in its course when potentially curative surgical treatment is not possible. The majority of patients are, therefore, candidates for systemic therapy. We review the patient and disease-related factors that contribute to the difficulties in the medical management of this condition and discuss new methods of assessing response to treatment, including the introduction of more clinically relevant novel end points such as clinical benefit response. We review the current trial literature examining the use of conventional cytotoxic agents in this disease, both as single agents and in combination. We also review the use of more novel targeted agents and examine their potential utility in this disease. The use of the farnesyl transferase inhibitors, matrix metalloproteinase inhibitors, epidermal growth factor receptor antagonists, and angiogenesis inhibitors is discussed.

Acquired resistance of pancreatic cancer cells towards 5-Fluorouracil and gemcitabine is associated with altered expression of apoptosis-regulating genes

OBJECTIVES

Resistance to chemotherapy is a major cause of treatment failure and poor prognosis in pancreatic cancer. Inasmuch as most effects of chemotherapeutic agents are mediated via the activation of apoptosis, the cytotoxic effects of gemcitabine and 5-fluorouracil (FU) in correlation with apoptosis-regulating genes in pancreatic cancer cell lines were analyzed.

METHODS

The cytotoxic effects of 5-FU and gemcitabine in AsPC-1, Capan-1, Mia-PaCa-2 and T3M4 pancreatic cancer cell lines were assessed by growth assays, and mRNA expression levels of pro-apoptotic and anti-apoptotic genes of the Bcl-2 family were analyzed by RNAse protection assays.

RESULTS

Pancreatic cancer cells displayed a wide range of responses towards 5-FU (IC(50) 0.22-4.63 microM) and gemcitabine (11.51-42.2 nM). After repeated treatment with 5-FU, the IC(50) values in Capan-1 and T3M4 cells increased 2.1- and 1.8-fold, respectively, compared to their parental cells. Following recurrent treatment with gemcitabine, the IC(50) values in Capan-1 cells increased significantly (1.5-fold, p < 0.01). RNase protection assay showed a negative correlation between bcl-x(L) and mcl-1 mRNA expression levels and the sensitivity to 5-FU and gemcitabine after 5-FU and gemcitabine treatment. The bax/bcl-2 ratio maintained relatively stable following 5-FU/gemcitabine treatment and reflected the chemotherapeutic sensitivity of these cell lines.

CONCLUSIONS

These findings reveal that pancreatic cancer cell lines are generally resistant to 5-FU and are more sensitive towards gemcitabine. The bax/bcl-2 ratio is predictive of chemotherapy sensitivity, whereas bcl-x(L) and mcl-1 mRNA levels following repeated exposure to 5-FU or gemcitabine are associated with resistance to these drugs. These findings suggest that the activation of anti-apoptotic genes after repeated drug exposure contributes to chemoresistance of pancreatic cancer cells and that blockage of anti-apoptotic genes might enhance chemosensitivity in pancreatic cancer.

Survival and quality of life in gastrointestinal tumors: two different end points?

BACKGROUND

In gastrointestinal tumors, the traditional end point of medical treatment was represented mainly by survival. In the last few years, however, there has been an increasing awareness about the role of quality of life.

DESIGN

This paper seeks to discuss these two important end points and their relationship in colorectal, gastric, pancreatic and liver cancers.

RESULTS

Chemotherapy has doubled survival in comparison with best supportive care in gastrointestinal tumors. A subjective response, represented by a decrease in cancer-related symptoms is expected in about half of the symptomatic patients in colorectal and gastric cancer. In pancreatic cancer, the positive results in terms of clinical benefit helped define the role of chemotherapy. Although clinical benefit does not represent a validated tool to measure quality of life, it can be a first step in the definition of new, simpler tools to assess this end point. The frequent presence of a serious concomitant disease, liver cirrhosis, in patients with hepatocellular carcinoma (HCC) usually prevents the use of chemotherapy in these tumors, which are often treated with locoregional treatments. Unfortunately, their impact on the survival and quality of life of these patients has never been adequately assessed.

CONCLUSIONS

In many gastrointestinal cancers, chemotherapy can produce a survival gain and an improvement in the quality of life. Further studies assessing new drugs and/or combinations should focus on these aspects and their relationships. In particular, the impact of treatments of HCC on both survival and quality of life must be investigated by well-designed prospective trials. When assessing the value of a particular anticancer treatment, it is important to consider the impact it may have not only on survival but also on quality of life. This is particularly so for cancer patients, whose life expectancy may be short.

Toxicity of a 24-hour infusion of gemcitabine in biliary tract and pancreatic cancer: a pilot study

The antitumor activity of gemcitabine is not dose-response related but schedule-dependent. Based on the results of a published phase I study in patients with nonsmall-cell lung cancer we started a pilot study of a 24-hr infusion of gemcitabine in patients with adenocarcinoma of the pancreas and biliary tract cancer. Twenty-five patients were enrolled and received a 24-hr infusion of gemcitabine once weekly on three consecutive out of 4 weeks. Dose levels of gemcitabine ranged from 100 to 150 mg/m2. One of 13 chemotherapy-naive patients had a partial response. Dose-limiting toxicity (DLT) was thrombocytopenia in pretreated patients and neutropenia in chemotherapy-naive patients. Other toxicities were oral mucositis, fever, flu-like symptoms, and asthenia. Maximum tolerated dose (MTD), especially in pretreated patients, was 100 mg/m2.

Gemcitabine in advanced pancreatic cancer: a phase II trial

The 5-year survival for pancreatic cancer is usually less than 5%, and no treatment has demonstrated consistent effect on patient survival and disease-related symptoms. Early studies with gemcitabine suggested a modest antitumor activity with significant improvement in disease-related symptoms. This phase II study reports the activity of gemcitabine on 33 consecutive patients with unresectable pancreatic carcinoma. Twenty-three patients had metastatic and 10 locally advanced unresectable disease. Twenty-six patients had not received any previous treatment and seven had received first-line chemotherapy with 5-fluorouracil. Gemcitabine 1,000 mg/m2 was administered intravenously in 30 minutes in the first cycle once weekly for up to 7 weeks followed by 1 week rest; then in subsequent cycles, once weekly for 3 of every 4-week cycle. Four patients obtained partial response (12%). Fifteen patients (45%) had stable disease with a median duration of 32 weeks (range: 16-75 weeks), and 14 patients experienced progressive disease. Median duration of response was 34.5 weeks (range: 19-50 weeks). Median survival was 33 weeks (range: 2-91 weeks). All 4 responding patients and 14 of 15 (93%) patients with stable disease had improvement in performance status and decrease in daily analgesic requirement. Toxicity was mild and mainly consisted of moderate and rapidly reversible myelosuppression. We conclude that gemcitabine chemotherapy was very well tolerated and determined a significant clinical improvement with modest antitumoral activity in patients with advanced pancreatic cancer.

Phase II evaluation of continuous-infusion 5-fluorouracil, leucovorin, mitomycin-C, and oral dipyridamole in advanced measurable pancreatic cancer: a North Central Cancer Treatment Group Trial

At present there remains a need for more effective systemic therapy in advanced pancreatic cancer. Some studies have suggested that infusional chemotherapy schedules and biomodulation of 5-fluorouracil (5-FU) may improve the therapeutic outcome in advanced colon cancer. One such regimen that uses continuous infusion 5-FU, weekly leucovorin, daily dipyridamole, and intermittent mitomycin-C has activity in both colon and unresectable pancreatic carcinoma. The intent of this trial was to test the effectiveness of this four-drug regimen in advanced pancreatic cancer. Patients received 5-FU 200 mg/m2 daily by continuous infusion, leucovorin 30 mg/m2 IV weekly, mitomycin-C 10 mg/m2 day 1, and dipyridamole 75 mg orally four times daily for 5 weeks. After a 1-week break, treatment cycles were repeated every 6 weeks. Eligibility included biopsy-proven advanced measurable pancreatic cancer, Eastern Cooperative Oncology Group performance status 0 and 2, and no prior systemic chemotherapy. Of 46 evaluable patients, 9 partial responses and 1 complete tumor response were seen, for an overall response rate of 22% (95% confidence interval 11-36%). The median survival in the group of 50 patients registered to this trial was 4.6 months, with a range of 0.33 to 40.2 months. Toxicity was manageable, with the most common toxicities (> or =grade III National Cancer Institute Common Toxicity Criteria) being anorexia (13%), stomatitis (17%), and hand-foot syndrome (13%). Of note, little severe hematologic toxicity and no significant headaches were reported. Although some patients did respond, the therapeutic results are not encouraging enough to take this regimen to phase III testing.