New directions in systemic therapy of pancreatic cancer

14-3-3σ regulation of and interaction with YAP1 in acquired gemcitabine resistance via promoting ribonucleotide reductase expression

Gemcitabine is an important anticancer therapeutics approved for treatment of several human cancers including locally advanced or metastatic pancreatic ductal adenocarcinoma (PDAC). Its clinical effectiveness, however, is hindered by existence of intrinsic and development of acquired resistances. Previously, it was found that 14-3-3σ expression associates with poor clinical outcome of PDAC patients. It was also found that 14-3-3σ expression is up-regulated in gemcitabine resistant PDAC cells and contributes to the acquired gemcitabine resistance. In this study, we investigated the molecular mechanism of 14-3-3σ function in gemcitabine resistance and found that 14-3-3σ up-regulates YAP1 expression and then binds to YAP1 to inhibit gemcitabine-induced caspase 8 activation and apoptosis. 14-3-3σ association with YAP1 up-regulates the expression of ribonucleotide reductase M1 and M2, which may mediate 14-3-3σ/YAP1 function in the acquired gemcitabine resistance. These findings suggest a possible role of YAP1 signaling in gemcitabine resistance.

Laser-induced drug release for local tumor control--a proof of concept

BACKGROUND

The systemic palliative chemotherapy of locally extended gastrointestinal and hepatobiliary tumors is associated with a considerable burden for the patient. The aim of this project was to develop a new drug release system to improve the local stent therapy in these patients as a proof of concept study. For this purpose, polymer filaments were modified with drug-loaded polymer microgels that allow selective release of the active substance by photochemical triggering using laser radiation. Integrated into a stent system, the better local tumor control could thus contribute to a significant increase in the quality of life of patients.

METHODS

A standard mammalian cell line and two carcinoma cell lines were established. By Fluorescence activated cell sorting (FACS), the cytotoxicity of the different materials was determined in vitro before and after drug loading with the chemotherapeutic agent 5-Fluorouracil (5-FU). For this purpose, the locally applied 5-FU concentration was previously determined by Bromdesoxyuridin assay. 5-FU dimer was synthesized by photo-induced dimerization of 5-FU in the presence of benzophenone in methanol. The chemical structure of 5-FU dimer was confirmed with Hydrogen-1 nuclear magnetic resonance and Fluorine-19 nuclear magnetic resonance. 5-FU dimer is nonsoluble in water and can be easily incorporated in polymer microgels modified with hydrophobic binding domains (cyclodextrin). After laser irradiation, 5-FU dimer decomposes and 5-FU can be released from microgels. Finally, the measurements were repeated after this laser-induced drug release.

RESULTS

In FACS analysis, neither the microgels nor the microgel cumarin complexes showed a significant difference in comparison with the negative control with H2O and therefore no toxic effect on the cell lines. After loading with the 5-FU dimer, there was no significant cell death (contrary to the pure 5-FU monomer, which dose had been previously tested as highly toxic). After laser-induced dissociation back to monomer and the associated drug release, FACS analysis showed cytotoxicity.

CONCLUSIONS

It was possible to develop 5-FU dimerloaded microgels, which show no cytotoxic effect on cell lines before laser irradiation. After dissociation back to 5-FU monomer by selective photochemical triggering using laser irradiation, the active substance was released. Thus, a new drug release system has been created and tested in vitro. For further development, integration into a stent system and for in vivo follow-up evaluation more studies need to be conducted.

Advanced phase I/II studies of targeted gene delivery in vivo: intravenous Rexin-G for gemcitabine-resistant metastatic pancreatic cancer

Rexin-G, a nonreplicative pathology-targeted retroviral vector bearing a cytocidal cyclin G1 construct, was tested in a phase I/II study for gemcitabine-resistant pancreatic cancer. The patients received escalating doses of Rexin-G intravenously from 1 × 10¹¹ colony-forming units (cfu) 2–3× a week (dose 0–1) to 2 × 10¹¹ cfu 3× a week (dose 2) for 4 weeks. Treatment was continued if there was less than or equal to grade 1 toxicity. No dose-limiting toxicity (DLT) was observed, and no vector DNA integration, replication-competent retrovirus (RCR), or vector-neutralizing antibodies were noted. In nine evaluable patients, 3/3 patients had stable disease (SD) at dose 0–1. At dose 2, 1/6 patients had a partial response (PR) and 5/6 patients had SD. Median progression-free survival (PFS) was 3 months at dose 0–1, and >7.65 months at dose 2. Median overall survival (OS) was 4.3 months at dose 0–1, and 9.2 months at dose 2. One-year survival was 0% at dose 0–1 compared to 28.6% at dose 2, suggesting a dose–response relationship between OS and Rexin-G dosage. Taken together, these data indicate that (i) Rexin-G is safe and well tolerated, and (ii) Rexin-G may help control tumor growth, and may possibly prolong survival in gemcitabine-resistant pancreatic cancer, thus, earning US Food and Drug Administration's (FDA) fast-track designation as second-line treatment for pancreatic cancer.

Endoscopic ultrasound-guided intratumoural therapy for pancreatic cancer

Pancreatic cancer is the second most frequent gastrointestinal malignancy and carries a dismal prognosis. The current standard of care includes resection, if possible, as well as systemic chemoradiation therapy. Endoscopic ultrasound (EUS) is an established technique for the diagnosis and staging of pancreatic adenocarcinoma. Interventional EUS via fine needle injection (FNI) for the treatment of pancreatic cancer is a rapidly expanding field. The present article reviews the up-to-date developments in EUS FNI for intratumoural pancreatic cancer therapy, including antitumoural agents, immunotherapy, ablative techniques and new delivery systems. The therapeutic modalities discussed are currently under development and will hopefully reach clinical practice if benefit is demonstrated through clinical trials. EUS FNI may be an exciting new technique for the delivery of desperately needed novel therapies for pancreatic cancer.

[The role of neoadjuvant chemoradiation in pancreatic cancer]

Although complete surgical resection, when possible, leads to prolonged survival in pancreatic cancer, if used alone, its results remain sub-optimal. Neoadjuvant strategies are recent in pancreatic cancer: in primary resectable tumors, they ensure that all patients obtain additional treatment to complete surgery; in locally advanced tumors, they allow a better selection of candidates for curative resection. By delaying surgery, neoadjuvant strategies modify the initial diagnostic process and the symptomatic treatment of pancreatic cancer. Several recent phase I-II studies have confirmed the feasibility and efficacy of the association of chemotherapy and radiotherapy, which is well-tolerated and is associated with better local control and survival. Due to the aggressiveness of pancreatic cancers, most recent cytotoxic agents should be associated with modern radiation techniques. Neoadjuvant chemoradiation is under evaluation in pancreatic cancers, and no randomized phase III trials comparing neoadjuvant and adjuvant therapeutic sequences has been reported. Moreover, radiological and pathological evaluations, not only at diagnosis, but also after preoperative chemoradiation, must be standardized to improve the selection of patients who will benefit from this multi-modal treatment.

Gemcitabine chemotherapy versus 5-fluorouracil-based concurrent chemoradiotherapy in locally advanced unresectable pancreatic cancer

OBJECTIVES

The aim of this study was to compare the survival benefits associated with gemcitabine chemotherapy and 5-fluorouracil (5-FU)-based concurrent chemoradiotherapy (CCRT) in locally advanced unresectable pancreatic cancer.

METHODS

One hundred and thirty-eight locally advanced unresectable pancreatic cancer patients were retrospectively enrolled from January 1995 to January 2005. All cases were histologically proven, and patients received gemcitabine chemotherapy, 5-FU-based CCRT, or supportive care at Seoul National University Hospital.

RESULTS

Median overall survival was 8.2 months. Twenty-six patients received gemcitabine chemotherapy, 56 patients 5-FU-based CCRT, and 56 patients supportive care. Weight loss and treatment modality were identified as independent prognostic factors by multivariate analysis. Patients in the 5-FU-based CCRT (overall survival, 10.4 months) and gemcitabine chemotherapy (11.3 months) groups showed survival benefit over those received supportive care (6.1 months, P < 0.0001). No grades 3 to 4 toxic adverse effects occurred in either treatment group and no statistical significant survival difference was found between gemcitabine chemotherapy and 5-FU-based CCRT (P = 0.5).

CONCLUSIONS

Patients with locally advanced pancreatic cancer who received gemcitabine chemotherapy or 5-FU-based CCRT showed better survival than those who received supportive care only. Gemcitabine chemotherapy and 5-FU-based CCRT showed similar survival advantages.

Detection of recurrent pancreatic cancer: comparison of FDG-PET with CT/MRI

OBJECTIVE

To determine the value of fluorine-18-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) for the detection of recurrent pancreatic cancer in comparison to computed tomography (CT) and magnetic resonance imaging (MRI).

METHODS

Thirty-one patients with suspected recurrence after surgery were included. Inclusion criteria were sudden weight loss, pain or increased CA 19-9 levels. FDG-PET was performed in all patients. After visual analysis, maximal standardized uptake values (SUVmax) were determined by placing regions of interest on the pancreas bed. Additionally, all patients underwent contrast-enhanced multidetector CT (n = 14) or MR (n = 17) imaging. Positive findings at FDG-PET or CT/MRI were compared to follow-up.

RESULTS

All patients relapsed. Of 25 patients with local recurrences upon follow-up, initial imaging suggested relapse in 23 patients. Of these, FDG-PET detected 96% (22/23) and CT/MRI 39% (9/23). Local SUVmax ranged from 2.26 to 16.9 (mean, 6.06). Among 12 liver metastases, FDG-PET detected 42% (5/12). CT/MRI detected 92% (11/12) correctly. Moreover, 7/9 abdominal lesions were malignant upon follow-up of which FDG-PET detected 7/7 and CT/MR detected none. Additionally, FDG-PET detected extra-abdominal metastases in 2 patients.

CONCLUSION

In patients suspected of pancreatic cancer relapse; FDG-PET reliably detected local recurrences, whereas CT/MRI was more sensitive for the detection of hepatic metastases. Furthermore, FDG-PET proved to be advantageous for the detection of nonlocoregional and extra-abdominal recurrences.

Pancreatic enzyme extract improves survival in murine pancreatic cancer

OBJECTIVES

The disappointing current therapeutic approaches for pancreatic cancer (PC) represent an urgent need for the development of novel methods to control the disease. Based on a recent report on the effectiveness of pancreatic enzyme therapy, we examined the effect of porcine pancreatic enzyme extracts (PPE) on human PC xenografts in nude mice.

METHODS

The malignant human PC cell line AsPC1 was transplanted into the pancreas of male beige XID nude mice that were treated or not with PPE in drinking water. The survival, size, and volume of tumors, plasma pancreatic enzyme levels, fecal fat, and urine were examined as were the expression of transforming growth factor alpha, insulinlike growth factor-I, epidermal growth factor, epidermal growth factor receptor, apoptosis, and proliferation rate of tumor cells.

RESULTS

PPE-treated mice survived significantly longer than the control group (P < 0.002). Tumors in the PPE-treated group were significantly smaller than in the control group. All mice in the control group showed steatorrhea, hyperglucosuria, hyperbilirubinuria, and ketonuria at early stages of tumor growth, whereas only a few in the treated group showed some of these abnormalities at the final stage. There were no differences in the expression of growth factors, epidermal growth factor receptor, or the apoptotic rate between the tumors of treated and control mice.

CONCLUSIONS

The treatment with PPE significantly prolongs the survival of mice with human PC xenografts and slows the tumor growth. The data indicate that the beneficial effect of PPE on survival is primarily related to the nutritional advantage of the treated mice.

Old and new drugs in systemic therapy of pancreatic cancer

BACKGROUND

The incidence of pancreatic cancer nearly equals its death rate (97%). Two-year survival is about 10%. Chemotherapy treatment is problematic because of the palliative and limited duration of response.

MATERIAL AND METHODS

The article analyzes the objective response and median survival time (MST) for old and new drugs in the treatment of pancreatic cancer.

RESULTS

The most encouraging results to date come from studies of 5-fluorouracil (5FU) as an adjuvant therapy and of gemcitabine in the advanced disease, which is one of the most active and best tolerated drugs in recent years. However, with the introduction of new drugs or with different old drug associations, interesting results are also becoming evident.

CONCLUSIONS

New approaches to CT treatment are necessary. Patient enrollment into rigorous and well conducted clinical trials, either at tumor diagnosis or after tumor recurrence, will generate new information regarding investigational therapies and it will offer improved therapies for patients with this disease.

Prevention of chemotherapy-related toxic side effects by infection with adeno-associated virus type 2

Drug resistance and toxic side effects are major limiting factors in the clinical use of antineoplastic chemotherapy. Patients with pancreatic cancer generally do not benefit from chemotherapy. The nonpathogenic adeno-associated virus type 2 (AAV-2) has been shown to sensitize human tumor cells to gamma irradiation and chemotherapeutic drugs. In the present study, we characterized the therapeutic role of AAV-2 infection in combination with 5-fluorouracil (5-FU)-based chemotherapy on pancreatic cancer cells in an animal model. In Lewis rats bearing s.c. implants of syngeneic DSL6A pancreatic cancer cells, intratumoral infection with AAV-2 (MOI 10E8 i.u.) in combination with 5-FU (5 or 50 mg/kg body weight) resulted in significantly reduced tumor growth and prolonged survival time compared with 5-FU single therapy. Most surprisingly, AAV-2-infected rats remained in a much better physical condition compared to their noninfected counterparts. While rats treated with 5-FU single therapy lost weight, were sluggish and died within 4 months after tumor implantation, animals infected with AAV showed much better vigilance, with body weight, leukocyte number and hemoglobin levels similar to healthy rats. In particular, 5-FU-related side effects like thrombocytopenia and leukopenia were significantly reduced in animals treated with the combination regimen. By in vitro analysis, human (Capan-1 and DANG) pancreatic cancer cell lines were shown to be sensitized to 5-FU chemotherapy to an extent similar to DSL6A cells. AAV-2 infection enhanced 5-FU-induced apoptosis by a factor of 8 to 14 in both human and rat pancreatic cancer cell lines. The data suggest that infection with the nonpathogenic AAV-2 significantly improves both chemotherapy efficacy and physical appearance and offers a novel strategy in cancer treatment.

Cyclooxygenases and lipoxygenases as potential targets for treatment of pancreatic cancer

Pancreatic adenocarcinoma is characterized by poor prognosis, late diagnosis and lack of response to conventional therapies. The incidence of this disease shows no sign of declining in the Western world. Thus, new targets need to be identified for pancreatic cancer treatment. In particular, new chemotherapeutic agents would be extremely beneficial for control of unresectable cancer and metastatic lesions as well as for prevention of this deadly disease. Mounting evidence suggests that both lipoxygenases (LOXs) and cyclooxygenases (COXs), the key enzymes for arachidonic acid metabolism, have a profound influence on the development and progression of several human cancers. Recent evidence suggests that both COX and LOX pathways are important in pancreatic cancer. Results from immunocytochemical, RT-PCR, and Western blotting studies have shown that COX, specifically COX-2, is upregulated in human pancreatic cancer cell lines as well as human pancreatic cancer tissues compared with normal ductal cells and normal pancreas specimens. Agents that block COX enzymes significantly inhibit pancreatic cancer growth both in vitro and in vivo, in parallel with induction of apoptosis. Expression of both 5-LOX and 12-LOX is also seen in pancreatic cancer, although compared to the expression of COX this has not been extensively investigated. Chemical inhibitors or antisense oligonucleotides that block either 5-LOX or 12-LOX cause marked inhibition of pancreatic cancer cell proliferation. On the other hand, LOX metabolites stimulate growth of the tumor cells and reverse LOX-inhibitor-induced growth inhibition, suggesting the specific role of LOX in regulating pancreatic cancer cell proliferation. Although questions still need to be answered, such as the underlying mechanisms for COX and LOX-induced growth inhibition, both COX and LOX pathways are potential targets for pancreatic cancer treatment and chemoprevention. COX and LOX enzyme inhibitors are available and have been shown to be relatively safe in the treatment of other diseases.