Monoclonal antibodies in the treatment of pancreatic cancer

Integrated PK/PD Modeling Relates Smoothened Inhibitor Biomarkers to The Heterogeneous Intratumor Disposition of Cetuximab in Pancreatic Cancer Tumor Models

Therapeutic antibodies have shown little efficacy in the treatment of pancreatic ductal adenocarcinomas (PDAC). Tumor desmoplasia, hypovascularity, and poor perfusion result in insufficient tumor cell exposure, contributing to treatment failure. Smoothened inhibitors of hedgehog signaling (sHHi) increase PDAC tumor permeability, perfusion, and drug delivery, and provide a tool to develop a quantitative, mechanistic understanding as to how the temporal dynamics of tumor priming can impact intratumor distribution of monoclonal antibodies (mAb). A linked pharmacokinetic (PK)/pharmacodynamic (PD) model was developed to integrate the plasma and tumor PK of a sHHi priming agent with its effects upon downstream stromal biomarkers Gli1, hyaluronic acid, and interstitial fluid pressure in PDAC patient-derived xenograft (PDX) tumors. In parallel, in situ tumor concentrations of cetuximab (CTX: anti-epidermal growth factor receptor; EGFR) were quantified as a marker for tumor delivery of mAb or antibody-drug conjugates. A minimal, physiologically-based pharmacokinetic (mPBPK) model was constructed to link sHHi effects upon mechanistic effectors of tumor barrier compromise with the intratumor distribution of CTX, and CTX occupancy of EGFR in tumors. Integration of the mPBPK model of mAb deposition and intratumor distribution with the PK/PD model of tumor responses to priming not only identified physiological parameters that are critical for tumor antibody distribution, but also provides insight into dosing regimens that could achieve maximal tumor disposition of therapeutic antibodies under conditions of transient PDAC tumor permeability barrier compromise that mechanistically-diverse tumor priming strategies may achieve.

Advances in Immunotherapeutics in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) accounts for up to 95% of all pancreatic cancer cases and is the seventh-leading cause of cancer death. Poor prognosis is a result of late presentation, a lack of screening tests and the fact some patients develop resistance to chemotherapy and radiotherapy. Novel therapies like immunotherapeutics have been of recent interest in pancreatic cancer. However, this field remains in its infancy with much to unravel. Immunotherapy and other targeted therapies have yet to yield significant progress in treating PDAC, primarily due to our limited understanding of the disease immune mechanisms and its intricate interactions with the tumour microenvironment (TME). In this review we provide an overview of current novel immunotherapies which have been studied in the field of pancreatic cancer. We discuss their mechanisms, evidence available in pancreatic cancer as well as the limitations of such therapies. We showcase the potential role of combining novel therapies in PDAC, postulate their potential clinical implications and the hurdles associated with their use in PDAC. Therapies discussed with include programmed death checkpoint inhibitors, Cytotoxic T-lymphocyte-associated protein 4, Chimeric Antigen Receptor-T cell therapy, oncolytic viral therapy and vaccine therapies including KRAS vaccines, Telomerase vaccines, Gastrin Vaccines, Survivin-targeting vaccines, Heat-shock protein (HSP) peptide complex-based vaccines, MUC-1 targeting vaccines, Listeria based vaccines and Dendritic cell-based vaccines.

Improved Therapeutic Delivery Targeting Clinically Relevant Orthotopic Human Pancreatic Tumors Engrafted in Immunocompromised Pigs Using Ultrasound-Induced Cavitation: A Pilot Study

Pancreatic tumors can be resistant to drug penetration due to high interstitial fluid pressure, dense stroma, and disarrayed vasculature. Ultrasound-induced cavitation is an emerging technology that may overcome many of these limitations. Low-intensity ultrasound, coupled with co-administered cavitation nuclei consisting of gas-stabilizing sub-micron scale SonoTran Particles, is effective at increasing therapeutic antibody delivery to xenograft flank tumors in mouse models. Here, we sought to evaluate the effectiveness of this approach in situ using a large animal model that mimics human pancreatic cancer patients. Immunocompromised pigs were surgically engrafted with human Panc-1 pancreatic ductal adenocarcinoma (PDAC) tumors in targeted regions of the pancreas. These tumors were found to recapitulate many features of human PDAC tumors. Animals were intravenously injected with the common cancer therapeutics Cetuximab, gemcitabine, and paclitaxel, followed by infusion with SonoTran Particles. Select tumors in each animal were targeted with focused ultrasound to induce cavitation. Cavitation increased the intra-tumor concentrations of Cetuximab, gemcitabine, and paclitaxel by 477%, 148%, and 193%, respectively, compared to tumors that were not targeted with ultrasound in the same animals. Together, these data show that ultrasound-mediated cavitation, when delivered in combination with gas-entrapping particles, improves therapeutic delivery in pancreatic tumors under clinically relevant conditions.

Immunotoxins and nanobody-based immunotoxins: review and update

Immunotoxins (ITs) are protein-based drugs that compose of targeting and cytotoxic moieties. After binding the IT to the specific cell-surface antigen, the IT internalises into the target cell and kills it. Targeting and cytotoxic moieties usually include monoclonal antibodies and protein toxins with bacterial or plant origin, respectively. ITs have been successful in haematologic malignancies treatment. However, ITs penetrate poorly into solid tumours because of their large size. Use of camelid antibody fragments known as nanobodies (Nbs) as a targeting moiety may overcome this problem. Nbs are the smallest fragment of antibodies with excellent tumour tissue penetration. The ability to recognise cryptic (immuno-evasive) target antigens, low immunogenicity, and high-affinity are other fundamental characteristics of Nbs that make them suitable candidates in targeted therapy. Here, we reviewed and discussed the structure and function of ITs, Nbs, and nanobody-based ITs. To gain sound insight into the issue at hand, we focussed on nanobody-based ITs.

Antibody therapy in pancreatic cancer: mAb-ye we're onto something?

Pancreatic cancer remains an extremely deadly disease, with little improvement seen in treatment or outcomes over the last 40 years. Targeted monoclonal antibody therapy is one area that has been explored in attempts to tackle this disease. This review examines antibodies that have undergone clinical evaluation in pancreatic cancer. These antibodies target a wide variety of molecules, including tumour cell surface, stromal, immune and embryonic pathway targets. We discuss the therapeutic utility of these therapies both as monotherapeutics and in combination with other treatments such as chemotherapy. While antibody therapy for pancreatic cancer has yet to yield significant success, lessons learned from research thus far highlights future directions that may help overcome observed hurdles to yield clinically efficacious results.

Modeling of Nanotherapy Response as a Function of the Tumor Microenvironment: Focus on Liver Metastasis

The tumor microenvironment (TME) presents a challenging barrier for effective nanotherapy-mediated drug delivery to solid tumors. In particular for tumors less vascularized than the surrounding normal tissue, as in liver metastases, the structure of the organ itself conjures with cancer-specific behavior to impair drug transport and uptake by cancer cells. Cells and elements in the TME of hypovascularized tumors play a key role in the process of delivery and retention of anti-cancer therapeutics by nanocarriers. This brief review describes the drug transport challenges and how they are being addressed with advanced in vitro 3D tissue models as well as with in silico mathematical modeling. This modeling complements network-oriented techniques, which seek to interpret intra-cellular relevant pathways and signal transduction within cells and with their surrounding microenvironment. With a concerted effort integrating experimental observations with computational analyses spanning from the molecular- to the tissue-scale, the goal of effective nanotherapy customized to patient tumor-specific conditions may be finally realized.

Targeting TM4SF5 with anti-TM4SF5 monoclonal antibody suppresses the growth and motility of human pancreatic cancer cells

Pancreatic cancer is one of the most lethal cancers. Transmembrane 4 superfamily member 5 protein (TM4SF5) is one of the candidate molecular targets used for the prevention and treatment of TM4SF5-expressing cancers, including hepatocellular carcinoma, colon cancer and pancreatic cancer. Recently, a previous study reported the preventive effects of a peptide vaccine, which targeted TM4SF5, in a mouse pancreatic cancer model. The present study investigated the implication of TM4SF5 and the suppressive effect of anti-human TM4SF5 monoclonal antibody (anti-hTM4SF5 antibody) in human pancreatic cancer cell lines in vitro. Treatment with anti-hTM4SF5 antibody reduced cell viability, modulated the expression of EMT markers Vimentin and E-cadherin, and decreased cell motility in human pancreatic cancer cells that endogenously expressed TM4SF5. When TM4SF5 was exogenously overexpressed in the TM4SF5-negative cell line, the cells indicated increased cell viability and motility compared with control cells, and the phenotype was reversed by anti-hTM4SF5 antibody treatment. Therefore, the results of the current study demonstrated that the high expression of TM4SF5 is a tumorigenic factor in human pancreatic cells and anti-hTM4SF5 antibody treatment exhibits a suppressive effect in TM4SF5-expressing pancreatic cancer cells.

Extradomain-B Fibronectin-Targeted Dextran-Based Chemical Exchange Saturation Transfer Magnetic Resonance Imaging Probe for Detecting Pancreatic Cancer

A dextran-peptide conjugate was developed for magnetic resonance (MR) molecular imaging of pancreatic ductal adenocarcinoma (PDAC) through its overexpressed microenvironment biomarker, extradomain-B fibronectin (EDB-FN). This new agent consists of diamagnetic and biocompatible dextran and a targeting peptide. Dextrans can be directly detected by chemical exchange saturation transfer magnetic resonance imaging (CEST MRI) without the need for radionuclide or metallic labeling. In addition, large molecular weight dextran, dextran 10 (MW ∼ 10 kDa), provides an approximately 50 times higher sensitivity per molecule than a single glucose unit. The potential of this highly biocompatible diamagnetic probe is demonstrated in a murine syngeneic allograft PDAC tumor model. The biocompatibility and sensitivity of this new agent clearly show potential for a path to clinical translation.

Monoclonal Antibody Production Against Vimentin by Whole Cell Immunization in a Mouse Model

Background

Pancreatic carcinoma is the fourth-leading cause of cancer death in the United States and due to its late presentation, only few patients would be candidates for the curative treatment of pancreactomy. Monoclonal antibodies have brought hope to targeted therapy.

Objectives

To identify new biomarkers, a panel of monoclonal antibodies was generated against newly established cell line, Faraz-ICR from a patient with pancreatic acinar cell carcinoma.

Material and Methods

Balb/c female mice were immunized with Faraz-ICR cell line and their spleenocytes fused with SP2/0 myeloma cell line. Highly reactive hybridoma producing antibodies against Faraz-ICR was detected using ELISA, immunofluorescence staining and flow cytometry. Western blot and 2D immunoblot were utilized for further characterization of the target antibodies.

Results

Among highly reactive clones, the reactivity of 7C11 clone was assessed in comparison to other epithelial tumors. The antibody isotype was IgM that reacted with a 55 kDa protein in western blot analysis. To further characterize the target antigen, immunoproteome of the Faraz-ICR cell line was performed. By LC-MS analysis, the target of 7C11 clone was identified to be vimentin.

Conclusions

Pancreatic cancer is a highly lethal malignancy with no reliable biomarker for early detection and diagnosis. In this study, by establishing a pancreatic acinar carcinoma cell line, a panel of monoclonal antibodies was generated to identify specific or associated cancer targets. Furthermore, 7C11 mAb was introduced that can specifically recognizes vimentin as a tumor marker. This antibody may serve as a new tool for prognostic and therapeutic strategies.

The active role of the transcription factor Sp1 in NFATc2-mediated gene regulation in pancreatic cancer

BACKGROUND

Adenocarcinoma of the pancreas is one of the most aggressive tumor diseases affecting the human body. The oncogenic potential of pancreatic cancer is mainly characterized by extremely rapid growth triggered by the activation of oncogenic signaling cascades, which suggests a change in the regulation of important transcription factors. Amongst others, NFAT transcription factors are assumed to play a central role in the carcinogenesis of pancreatic cancer. Recent research has shown the importance of the transcription factor Sp1 in the transcriptional activity of NFATc2 in pancreatic cancer. However, the role of the interaction between these two binding partners remains unclear. The current study investigated the role of Sp1 proteins in the expression of NFATc2 target genes and identified new target genes and their function in cells. A further objective was the domain of the Sp1 protein that mediates interaction with NFATc2. The involvement of Sp1 proteins in NFATc2 target genes was shown by means of a gene expression profile analysis, and the results were confirmed by quantitative RT-PCR. The functional impact of this interaction was shown in a thymidine incorporation assay. A second objective was the physical interaction between NFATc2 and different Sp1 deletion mutants that was investigated by means of immunoprecipitation.

RESULTS

In pancreatic cancer, the proto-oncogene c-Fos, the tumor necrosis factor TNF-alpha, and the adhesion molecule integrin beta-3 are target genes of the interaction between Sp1 and NFATc2. Loss of just one transcription factor inhibits oncogenic complex formation and expression of cell cycle-regulating genes, thus verifiably decreasing the carcinogenic effect. The current study also showed the interaction between the transcription factor NFATc2 and the N-terminal domain of Sp1 in pancreatic cancer cells. Sp1 increases the activity of NFATc2 in the NFAT-responsive promoter.

CONCLUSIONS

The regulation of gene promotors during transcription is a rather complex process because of the involvement of many proteins that - as transcription factors or co-factors - regulate promotor activity as required and control cell function. NFATc2 and Sp1 seem to play a key role in the progression of pancreatic cancer.

Immunotherapy, Radiotherapy, and Hyperthermia: A Combined Therapeutic Approach in Pancreatic Cancer Treatment

Pancreatic cancer (PC) has the highest mortality rate amongst all other cancers in both men and women, with a one-year relative survival rate of 20%, and a five-year relative survival rate of 8% for all stages of PC combined. The Whipple procedure, or pancreaticoduodenectomy, can increase survival for patients with resectable PC, however, less than 20% of patients are candidates for surgery at time of presentation. Most of the patients are diagnosed with advanced PC, often with regional and distant metastasis. In these advanced cases, chemotherapy and radiation have shown limited tumor control, and PC continues to be refractory to treatment and results in a poor survival outcome. In recent years, there has been intensive research on checkpoint inhibitor immunotherapy for PC, however, PC is characterized with dense stromal tissue and a tumor microenvironment (TME) that is highly immunosuppressive, which makes immunotherapy less effective. Interestingly, when immunotherapy is combined with radiation therapy (RT) and loco-regional hyperthermia (HT), it has demonstrated enhanced tumor responses. HT improves tumor killing via a variety of mechanisms, targeting both the tumor and the TME. Targeted HT raises the temperature of the tumor and surrounding tissues to 42–43 °C and makes the tumor more immunoresponsive. HT can also modulate the immune system of the TME by inducing and synthesizing heat shock proteins (HSP), which also activate an anti-tumor response. It is well known that HT can enhance RT-induced DNA damage in cancer cells and simultaneously help to oxygenate hypoxic regions. Thus, it is envisaged that combined HT and RT might have immunomodulatory effects in the PC-TME, making PC more responsive to immunotherapies. Moreover, the combined tripartite approach of immunotherapy, RT, and HT could reduce the overall toxicity associated with each individual therapy, while concomitantly enhancing the immunotherapeutic effect of overall individual therapies to treat local and metastatic PC. Thus, the use of a tripartite combinatorial approach could be promising and more efficacious than monotherapy or dual therapy to treat and increase the survival of the PC patients.

Interaction between NFATc2 and the transcription factor Sp1 in pancreatic carcinoma cells PaTu 8988t

BACKGROUND

Nuclear factors of activated T-cells (NFATs) have been mainly characterized in the context of immune response regulation because, as transcription factors, they have the ability to induce gene transcription. NFAT proteins are found in several types of tumors, for instance, pancreatic carcinoma. The role of NFATs in carcinogenesis is regulating central genes in cell differentiation and cell growth. NFAT proteins are primarily located in cytoplasm and only transported to the cell nucleus after activation. Here, they interact with other transcription factors cooperating with NFAT proteins, thus influencing the selection and regulation of NFAT-controlled genes. To identify and characterize possible interaction partners of the transcription factor NFATc2 in pancreatic carcinoma cells PaTu 8988t.

METHODS

NFATc2 expression and the mode of action of Ionomycin in the pancreatic tumor cell lines PaTu 8988t were shown with Western blotting and immunofluorescence tests. Potential partner proteins were verified by means of immunoprecipitation and binding partners, their physical interactions with DNA pull-down assays, siRNA technologies, and GST pull-down assays. Functional evidence was complemented by reporter-promoter analyses.

RESULTS

NFATc2 and Sp1 are co-localized in cell nuclei and physically interact at the NFAT target sequence termed NFAT-responsive promotor construct. Sp1 increases the functional activity of its binding partner NFATc2. This interaction is facilitated by Ionomycin in the early stimulation phase (up to 60 min).

CONCLUSIONS

Oncological therapy concepts are becoming more and more specific, aiming at the efficient modulation of specific signal and transcription pathways. The oncogenic transcription partner Sp1 is important for the transcriptional and functional activity of NFATc2 in pancreatic carcinoma. The binding partners interact in cells. Further studies are necessary to identify the underlying mechanisms and establish future therapeutic options for treating this aggressive type of tumor.

Production of a Mouse Monoclonal Antibody Against Mortalin by Whole Cell Immunization

Pancreatic carcinoma is the fourth leading cause of cancer death and is characterized by early invasion and metastasis. Advances in molecular biology directed new strategies in targeted therapy using monoclonal antibodies. To identify new biomarkers, we generated a panel of monoclonal antibodies against the newly established cell line, Faraz-ICR, from a patient with acinar cell carcinoma. After immunization of BALB/c female mice with Faraz-ICR cell line and fusion of splenocytes with SP2/0 myeloma cell line, high reactive hybridoma producing antibodies to Faraz-ICR were detected using enzyme-linked immunosorbent assay, immunofluorescence staining and flow cytometry. Western blot and two-dimensional immunoblot were used for further characterization of the targets antibodies. Among high reactive clones, the reactivity of 1C11 clone was assessed with other epithelial tumors. The isotype of the antibody was revealed to be IgM, and the antibody reacted to a protein with a molecular weight of about 70 kDa in Western blot analysis. To further characterization of the target antigen, immunoproteome of the Faraz-ICR cell line was performed. By liquid chromatography-mass spectrometry (LC-MS) analysis, we identified that the target of 1C11 clone was HSP70. In conclusion, pancreatic cancer is a fatal malignancy with no reliable biomarker for early screening and diagnosis. In this study, by establishing a pancreatic cell line, a panel of monoclonal antibodies was generated aiming to explore specific or associated cancer targets. We then introduced 1C11 monoclonal antibody that can specifically recognize mortalin as a main tumor marker and may serve as a new tool for diagnostic kit and therapeutic strategies targeting this molecule.

MUC4 mucin- a therapeutic target for pancreatic ductal adenocarcinoma

INTRODUCTION

Pancreatic cancer (PC) is characterized by mucin overexpression. MUC4 is the most differentially overexpressed membrane-bound mucin that plays a functional role in disease progression and therapy resistance. Area covered: We describe the clinicopathological significance of MUC4, summarize mechanisms contributing to its deregulated expression, review preclinical studies aimed at inhibiting MUC4, and discuss how MUC4 overexpression provides opportunities for developing targeted therapies. Finally, we discuss the challenges for developing MUC4-based therapeutics, and identify areas where efforts should be directed to effectively exploit MUC4 as a therapeutic target for PC. Expert opinion: Studies demonstrating that abrogation of MUC4 expression reduces proliferation and metastasis of PC cells and enhances sensitivity to therapeutic agents affirm its utility as a therapeutic target. Emerging evidence also supports the suitability of MUC4 as a potential immunotherapy target. However, these studies have been limited to in vitro, ex vivo or in vivo approaches using xenograft tumors in immunodeficient murine models. For translational relevance, MUC4-targeted therapies should be evaluated in murine models with intact immune system and accurate tumor microenvironment. Additionally, future studies evaluating MUC4 as a target for immunotherapy must entail characterization of immune response in PC patients and investigate its association with immunosuppression and survival.

Molecular Imaging of Pancreatic Cancer with Antibodies

Development of novel imaging probes for cancer diagnostics remains critical for early detection of disease, yet most imaging agents are hindered by suboptimal tumor accumulation. To overcome these limitations, researchers have adapted antibodies for imaging purposes. As cancerous malignancies express atypical patterns of cell surface proteins in comparison to noncancerous tissues, novel antibody-based imaging agents can be constructed to target individual cancer cells or surrounding vasculature. Using molecular imaging techniques, these agents may be utilized for detection of malignancies and monitoring of therapeutic response. Currently, there are several imaging modalities commonly employed for molecular imaging. These imaging modalities include positron emission tomography (PET), single-photon emission computed tomography (SPECT), magnetic resonance (MR) imaging, optical imaging (fluorescence and bioluminescence), and photoacoustic (PA) imaging. While antibody-based imaging agents may be employed for a broad range of diseases, this review focuses on the molecular imaging of pancreatic cancer, as there are limited resources for imaging and treatment of pancreatic malignancies. Additionally, pancreatic cancer remains the most lethal cancer with an overall 5-year survival rate of approximately 7%, despite significant advances in the imaging and treatment of many other cancers. In this review, we discuss recent advances in molecular imaging of pancreatic cancer using antibody-based imaging agents. This task is accomplished by summarizing the current progress in each type of molecular imaging modality described above. Also, several considerations for designing and synthesizing novel antibody-based imaging agents are discussed. Lastly, the future directions of antibody-based imaging agents are discussed, emphasizing the potential applications for personalized medicine.

Targeted therapies for pancreatic adenocarcinoma: Where do we stand, how far can we go?

Pancreatic adenocarcinoma (usually referred to as pancreatic cancer) is a highly lethal and aggressive malignancy with a disease-related mortality almost equaling its incidence, and one of the most challenging cancers to treat. The notorious resistance of pancreatic cancer not only to conventional cytotoxic therapies but also to almost all targeted agents developed to date, continues to puzzle the oncological community and represents one of the biggest hurdles to reducing the death toll from this ominous disease. This editorial highlights the most important recent advances in preclinical and clinical research, with regards to targeted therapeutics for pancreatic cancer, outlines current challenges and provides an overview of potential future perspectives in this rapidly evolving field.

Sensitization of Radiation or Gemcitabine-Based Chemoradiation Therapeutic Effect by Nimotuzumab in Pancreatic Cancer Cells

This study was performed to observe the effect of the combination of nimotuzumab with radiation or gemcitabine-based chemoradiation on antipancreatic cancer cell therapy. Pancreatic cancer cells (PANC-1) were treated with nimotuzumab alone or combined with radiation (2, 4, or 8 Gy), which was either with or without gemcitabine chemotherapy. Cell proliferation, cell cycle distribution, and apoptosis were observed. The inhibition rate, the percentage of G2/M phase arrest, and the apoptosis rate of the combined nimotuzumab with radiation group was significantly higher than the group without nimotuzumab (P < .001). The inhibition rate, the percentage of G2/M phase, and the apoptosis rate of the nimotuzumab therapy combined with gemcitabine-based chemoradiation group were obviously higher than that in gemcitabine-based chemoradiation group (P < .001). In conclusion, nimotuzumab could enhance the anticancer effect of radiation and gemcitabine-based chemoradiation in PANC-1 cancer cells because of the enhancement of cell cycle arrest and apoptosis.

Structural complementation of the catalytic domain of pseudomonas exotoxin A

The catalytic moiety of Pseudomonas exotoxin A (domain III or PE3) inhibits protein synthesis by ADP-ribosylation of eukaryotic elongation factor 2. PE3 is widely used as a cytocidal payload in receptor-targeted protein toxin conjugates. We have designed and characterized catalytically inactive fragments of PE3 that are capable of structural complementation. We dissected PE3 at an extended loop and fused each fragment to one subunit of a heterospecific coiled coil. In vitro ADP-ribosylation and protein translation assays demonstrate that the resulting fusions-supplied exogenously as genetic elements or purified protein fragments-had no significant catalytic activity or effect on protein synthesis individually but, in combination, catalyzed the ADP-ribosylation of eukaryotic elongation factor 2 and inhibited protein synthesis. Although complementing PE3 fragments are catalytically less efficient than intact PE3 in cell-free systems, co-expression in live cells transfected with transgenes encoding the toxin fusions inhibits protein synthesis and causes cell death comparably as intact PE3. Complementation of split PE3 offers a direct extension of the immunotoxin approach to generate bispecific agents that may be useful to target complex phenotypes.

Age Influences Likelihood of Pancreatic Cancer Treatment, but not Outcome

Background

Pancreatic cancer (PanCA) is predominantly diagnosed in elderly patients; nevertheless, a significant number of young patients are affected. We hypothesized more aggressive treatment of young PanCA patients would result in better overall survival (OS).

Methods

A retrospective review of our institutional cancer database identified subjects for inclusion. Age 50 years was selected to stratify patients into age groups.

Results

Of 309 PanCA patients, 54 (17%) were ≤ 50 years old. Exocrine cancer was the most common histology (90%). Patients ≤ 50 years old were more likely to have endocrine cancer (22% vs. 7%, P = 0.001). There was no difference in stage or curative intent surgery between age groups. Despite patients ≤ 50 years old receiving more chemotherapy (61% vs. 41%, P = 0.007) and radiotherapy (28% vs. 15%, P = 0.03), there was no difference in OS (24.1 months vs. 14.1 months, P = 0.08). When only exocrine cancers were considered, there was no difference between young and old patients regarding stage, grade, location or surgery. Exocrine cancer patients ≤ 50 years old received more chemotherapy (67% vs. 42%, P = 0.003) and radiation therapy (36% vs. 17%, P = 0.004), but there was no difference in OS.

Conclusions

A substantial number of PanCA patients are ≤ 50 years old. Patients ≤ 50 years old received more treatment but did not have improved OS. Significant improvements in PanCA survival await development of new treatment strategies.

Overcoming the stromal barrier for targeted delivery of HPMA copolymers to pancreatic tumors

Delivery of macromolecules to pancreatic cancer is inhibited by a dense extracellular matrix composed of hyaluronic acid, smooth muscle actin and collagen fibers. Hyaluronic acid causes a high intratumoral fluidic pressure which prevents diffusion and penetration into the pancreatic tumor. This study involves the breaking down of hyaluronic acid by treating CAPAN-1 xenograft tumors in athymic nu/nu mice with targeted N-(2-hydroxypropyl)methacrylamide (HPMA) copolymers radiolabeled with (111)In for single photon emission computerized tomography (SPECT) imaging. Two targeting strategies were investigated including αvβ3 integrin and HER2 receptors. HPMA copolymers were targeted to these receptors by conjugating short peptide ligands cRGDfK and KCCYSL to the side chains of the copolymer. Results demonstrate that tumor targeting can be achieved in vivo after treatment with hyaluronidase. This approach shows promise for enhanced delivery of polymer-peptide conjugates to solid tumors.

Targeting the MAGE A3 antigen in pancreatic cancer

Pancreatic cancer is the fourth-leading cause of death in the United States and one of the most aggressive known malignancies. New and innovative advances in treatment are desperately needed. One promising area of investigational treatment for pancreatic cancer involves the use of immunotherapy. The development of immunotherapy for pancreatic cancer has been hampered by difficulty in generating tumor-reactive lymphocytes from resected specimens and by a lack of appropriate target antigens expressed on tumor cells. Innovative strategies have been developed with the use of peripheral blood lymphocytes that are genetically engineered to express T-cell receptors targeting common tumor antigens, including cancer-testis antigens, such as the MAGE-A3 antigen. Cancer-testis antigens pose excellent targets for immunotherapy because they are expressed in cancer and in the testis, an immune-privileged site, but have limited expression in normal tissue. An additional advantage in targeting cancer-testis antigens for immunotherapy is that their expression can be selectively up-regulated in tumor cells via epigenetic regulation with chromatin remodeling agents. Current interest in targeting cancer-testis antigens in pancreatic cancer is well-founded because cancer-testis antigens have been shown to be expressed in pancreatic cancer as potential targets for therapy. In our studies, we validated the expression pattern of cancer-testis antigens in resected specimens of pancreatic cancer and tested the hypothesis that treatment of pancreatic cancer cells with chromatin remodeling agents would render them more sensitive to antigen-specific T lymphocytes. We focused predominately on the MAGE-A3 antigen because it is highly expressed in pancreatic cancer, and several immunotherapeutic strategies are in clinical trials targeting this specific antigen. The results of these studies have important translational implications and provide the rationale for combined treatment with chromatin remodeling agents and immunotherapeutic approaches for pancreatic cancer.

In pancreatic carcinoma, dual EGFR/HER2 targeting with cetuximab/trastuzumab is more effective than treatment with trastuzumab/erlotinib or lapatinib alone: implication of receptors' down-regulation and dimers' disruption

We previously demonstrated the synergistic therapeutic effect of the cetuximab (anti-epidermal growth factor receptor [EGFR] monoclonal antibody, mAb)-trastuzumab (anti-HER2 mAb) combination (2mAbs therapy) in HER2(low) human pancreatic carcinoma xenografts. Here, we compared the 2mAbs therapy, the erlotinib (EGFR tyrosine kinase inhibitor [TKI])-trastuzumab combination and lapatinib alone (dual HER2/EGFR TKI) and explored their possible mechanisms of action. The effects on tumor growth and animal survival of the three therapies were assessed in nude mice xenografted with the human pancreatic carcinoma cell lines Capan-1 and BxPC-3. After therapy, EGFR and HER2 expression and AKT phosphorylation in tumor cells were analyzed by Western blot analysis. EGFR/HER2 heterodimerization was quantified in BxPC-3 cells by time-resolved FRET. In K-ras-mutated Capan-1 xenografts, the 2mAbs therapy gave significantly higher inhibition of tumor growth than the erlotinib/trastuzumab combination, whereas in BxPC-3 (wild-type K-ras) xenografts, the erlotinib/trastuzumab combination showed similar growth inhibition but fewer tumor-free mice. Lapatinib showed no antitumor effect in both types of xenografts. The efficacy of the 2mAbs therapy was partly Fc-independent because F(ab')(2) fragments of the two mAbs significantly inhibited BxPC-3 growth, although with a time-limited therapeutic effect. The 2mAbs therapy was associated with a reduction of EGFR and HER2 expression and AKT phosphorylation. BxPC-3 cells preincubated with the two mAbs showed 50% less EGFR/HER2 heterodimers than controls. In pancreatic carcinoma xenografts, the 2mAbs therapy is more effective than treatments involving dual EGFR/HER2 TKIs. The mechanism of action may involve decreased AKT phosphorylation and/or disruption of EGFR/HER2 heterodimerization.

Single tumor imaging with multiple antibodies targeting different antigens

Antibodies are important drugs for treating cancer and there is strong rationale for using multiple antibodies to improve outcomes. We labeled two breast cancer binding antibodies, anti-ErbB2 and anti-EpCAM, with infrared fluorescence dyes of different wavelengths and determined their in vivo distribution in a breast cancer xenograft model using a near-infrared (NIR) fluorescence imaging system. Our data show that these two antibodies can be readily assessed simultaneously in mouse xenograft model. This will help guide design of dosing strategies for multiple antibodies and identify potential interaction that could affect pharmacokinetics and possible side effects.

Epidermal growth factor receptor and insulinlike growth factor 1 receptor expression predict poor survival in pancreatic ductal adenocarcinoma

BACKGROUND

The aim of this study was to evaluate the expression of epidermal growth factor receptor (EGFR) and insulinlike growth factor 1 receptor (IGF-1R) proteins and IGF-1R gene copy numbers in pancreatic ductal adenocarcinoma in relation to patients' characteristics and prognosis.

METHODS

Immunohistochemical staining was performed on formalin-fixed paraffin-embedded tissue derived from tumor specimens recovered during surgery. Slides were evaluated for membranous EGFR and IGF-1R staining using both the HercepTest and the semiquantitative H-score systems. Chromogenic in situ hybridization was performed to quantify IGF-1R gene copy number. The primary outcome was the association between EGFR expression, IGF-1R expression-in both neoplastic epithelial and stromal cells-or IGF-1R gene copy number and overall survival. Secondary outcomes included associations between EFGR and IGF-1R expression and pathologic variables.

RESULTS

A total of 105 patients were included. EGFR expression was present in 30.4% of cases and was associated with lymph node metastasis (P = .038). IGF-1R was overexpressed in 53% of tumors and correlated with higher tumor grade (P = .033). High membranous expression of EGFR (P < .001) and/or IGF-1R (P = .004), the cytoplasmic detection of EGFR (P = .027), and high expression levels of IGF-1R in the tumoral stroma (P < .001) were all associated with shorter overall survival, being significantly better in patients who simultaneously do not express membranous EGFR or stromal IGF-1R.

CONCLUSIONS

EGFR and IGF-1R expression, in neoplastic and stromal cells, seems to be an important prognostic factor.

On the selectivity and efficacy of defense peptides with respect to cancer cells

Here, we review potential determinants of the anticancer efficacy of innate immune peptides (ACPs) for cancer cells. These determinants include membrane-based factors, such as receptors, phosphatidylserine, sialic acid residues, and sulfated glycans, and peptide-based factors, such as residue composition, sequence length, net charge, hydrophobic arc size, hydrophobicity, and amphiphilicity. Each of these factors may contribute to the anticancer action of ACPs, but no single factor(s) makes an overriding contribution to their overall selectivity and toxicity. Differences between the anticancer actions of ACPs seem to relate to different levels of interplay between these peptide and membrane-based factors.

Evidence of an intracellular angiotensin-generating system and non-AT1, non-AT2 binding site in a human pancreatic cell line

OBJECTIVES

To assess the presence of a local angiotensin-generating systems (LAGS) and its participation in tumor growth in the human pancreatic cancer derived cell line Capan-1.

METHODS

Capan-1 cells were cultured in Dulbecco modified Eagle medium, and angiotensin I was assayed by radioimmunoassay and angiotensin II and vascular endothelial growth factor were assayed by enzyme-linked immunosorbent assay in the supernatant. Immunohistochemistry and reverse transcription-polymerase chain reaction were performed for the expression of AT1 and AT2 receptors. Angiotensin II binding assays and blockade were studied.

RESULTS

High levels of both angiotensins I and II were found in Capan-1 cells, although neither angiotensin I nor angiotensin II was detected in the cell culture supernatant. Reverse transcription-polymerase chain reaction and immunocytochemistry revealed that Capan-1 cells do not express AT1 and AT2 receptors; however, specific binding to the cell membrane was identified for angiotensin II. Neither exogenous angiotensin II nor Dup753 (specific AT1 receptor blocker) affected Capan-1 cells' proliferation or vascular endothelial growth factor secretion.

CONCLUSIONS

Detection of both angiotensin I and angiotensin II along with specific binding of angiotensin II in Capan-1 cells provides evidence of the existence of a LAGS that operates in an intracrine manner. Intracellular angiotensin II may play a role in the aggressiveness of pancreatic cancer and is a possible target for therapeutic agents.

Targeting solid tumors with non-pathogenic obligate anaerobic bacteria

Molecular-targeting drugs with fewer severe adverse effects are attracting great attention as the next wave of cancer treatment. There exist, however, populations of cancer cells resistant to these drugs that stem from the instability of tumor cells and/or the existence of cancer stem cells, and thus specific toxicity is required to destroy them. If such selectivity is not available, these targets may be sought out not by the cancer cell types themselves, but rather in their adjacent cancer microenvironments by means of hypoxia, low pH, and so on. The anaerobic conditions present in malignant tumor tissues have previously been regarded as a source of resistance in cancer cells against conventional therapy. However, there now appears to be a way to make use of these limiting factors as a selective target. In this review, we will refer to several trials, including our own, to direct attention to the utilizable anaerobic conditions present in malignant tumor tissues and the use of bacteria as carriers to target them. Specifically, we have been developing a method to attack solid cancers using the non-pathogenic obligate anaerobic bacterium Bifidobacterium longum as a vehicle to selectively recognize and target the anaerobic conditions in solid cancer tissues. We will also discuss the existence of low oxygen pressure in tumor masses in spite of generally enhanced angiogenesis, overview current cancer therapies, especially the history and present situation of bacterial utility to treat solid tumors, and discuss the rationality and future possibilities of this novel mode of cancer treatment.