Gemcitabine combined with gefitinib in patients with inoperable or metastatic pancreatic cancer: a phase II Study of the Hellenic Cooperative Oncology Group with biomarker evaluation

Targeting KRAS and SHP2 signaling pathways for immunomodulation and improving treatment outcomes in solid tumors

Historically, KRAS has been considered 'undruggable' inspite of being one of the most frequently altered oncogenic proteins in solid tumors, primarily due to the paucity of pharmacologically 'druggable' pockets within the mutant isoforms. However, pioneering developments in drug design capable of targeting the mutant KRAS isoforms especially KRASG12C-mutant cancers, have opened the doors for emergence of combination therapies comprising of a plethora of inhibitors targeting different signaling pathways. SHP2 signaling pathway, primarily known for activation of intracellular signaling pathways such as KRAS has come up as a potential target for such combination therapies as it emerged to be the signaling protein connecting KRAS and the immune signaling pathways and providing the link for understanding the overlapping regions of RAS/ERK/MAPK signaling cascade. Thus, SHP2 inhibitors having potent tumoricidal activity as well as role in immunomodulation have generated keen interest in researchers to explore its potential as combination therapy in KRAS mutant solid tumors. However, the excitement with these combination therapies need to overcome challenges thrown up by drug resistance and enhanced toxicity. In this review, we will discuss KRAS and SHP2 signaling pathways and their roles in immunomodulation and regulation of tumor microenvironment and also analyze the positive effects and drawbacks of the different combination therapies targeted at these signaling pathways along with their present and future potential to treat solid tumors.

Targeting KRAS in Solid Tumors: Current Challenges and Future Opportunities of Novel KRAS Inhibitors

Activating mutations in RAS family proteins are found in ~25% of all human cancers. Different solid tumors are correlated with mutations in certain isoforms of RAS, with Kirsten RAS (KRAS) being the most frequently mutated isoform. Historically, KRAS has been acknowledged as “undruggable”, largely because the RAS proteins do not appear to present suitable pockets to which small inhibitory molecules can bind. However, this scenario has changed over the last years with the advent of novel KRAS inhibitors. In this review, we describe the role of KRAS mutation across different solid tumors, providing data on novel KRAS inhibitors currently under development and an updated overview of ongoing research in this field. A literature search was performed to select papers, abstracts, and oral presentation on KRAS inhibitory strategies in KRAS mutated solid tumors. Overall, the most promising therapeutic results have been obtained with molecules targeting KRAS G12C, thus paving the way for a significant therapeutic improvement in non-small cell lung cancer. Unfortunately, KRAS G12C mutation is rather uncommon in other solid tumors, namely pancreatic ductal adenocarcinoma and colorectal cancer. Several combination strategies are currently under evaluation in clinical trials, in order to bypass the resistance mechanisms responsible for the intrinsic resistance of mutated KRAS to the main therapeutic strategies adopted to date. Results suggest that the therapeutic scenario of KRAS has started to change, and further research will bring therapeutic results in this field.

Pancreatic adenocarcinoma: molecular drivers and the role of targeted therapy

Prognosis from pancreatic ductal adenocarcinoma (PDAC) continues to be poor despite the many efforts channeled to improve its management. Although the mainstay treatment is still traditional chemotherapy, recent advances highlighted a promising potential for targeted therapy in the management of this disease. Those advances emphasize the significance of timely genomic profiling of tumor tissue as well as germline testing of patients to identify potential markers of targeted therapy. While targeted therapy is reserved for a relatively small subset of patients with PDAC, ongoing research is uncovering additional markers, and targeted agents, that will hopefully translate to better outcomes for patients.

In Silico Design and Experimental Validation of Combination Therapy for Pancreatic Cancer

The number of deaths associated with Pancreatic Cancer has been on the rise in the United States making it an especially dreaded disease. The overall prognosis for pancreatic cancer patients continues to be grim because of the complexity of the disease at the molecular level involving the potential activation/inactivation of several diverse signaling pathways. In this paper, we first model the aberrant signaling in pancreatic cancer using a multi-fault Boolean Network. Thereafter, we theoretically evaluate the efficacy of different drug combinations by simulating this boolean network with drugs at the relevant intervention points and arrive at the most effective drug(s) to achieve cell death. The simulation results indicate that drug combinations containing Cryptotanshinone, a traditional Chinese herb derivative, result in considerably enhanced cell death. These in silico results are validated using wet lab experiments we carried out on Human Pancreatic Cancer (HPAC) cell lines.

Impact of ethanolic extract of Equisetum arvense (EA1) on pancreatic carcinoma AsPC-1 cells

The current research was focused on evaluation of the cytotoxic and suppressive action of ethanolic extract of Equisetum arvense (EA1) against human pancreatic carcinoma cell line ASPC-1 after treatment with 25 µg/mL, 50 µg/mL, 100 µg/mL and 200 µg/mL EA1, using MTT assay and Antioxidant activity. Detailed investigations led to reveal the ability of cell patronage through the dreadful upshot of free radicals. The current approach followed MTT assays to examine the long-lasting ability and growth of cells as EA1 restrained the cell viability and growth of ASPC-1. At the end, EA1 showed its potential cytotoxicity and reduced the cellular proliferation of ASPC-1 cells through a pattern, which appeared to be concentration dependent. Our results can form the basis to explore the molecular mechanisms underlying Ethanolic Extract of Equisetum arvense induced cell death in pancreatic cancer cell lines and may serve as an alternative anticancer agent for the treatment of pancreatic carcinoma (PC) with no or least side effects to the patient.

A Retrospective Look at Anti-EGFR Agents in Pancreatic Cancer Therapy

Background:

The introduction of Monoclonal Antibodies (mAbs) and small-molecule Tyrosine Kinase Inhibitors (TKIs) that target the Epidermal Growth Factor Receptor (EGFR), marks a huge step forward in the Pancreatic Cancer (PC) therapy. However, anti-EGFR therapy is found to be successful only in a fraction of patients. Although anti-EGFR agents have shown considerable clinical promise, a serious adverse event associated with anti- EGFR therapy has been challenging. At this juncture, there is still more to be done in the search for effective predictive markers with therapeutic applicability.

Methods:

A focused literature search was conducted to summarize the existing evidence on anti-EGFR agents in pancreatic cancer therapy.

Results:

This review discusses various anti-EGFR agents currently in use for PC therapy and potential adverse effects associated with it. Existing evidence on EGFR TKIs demonstrated better tolerant effects and outcomes with multiple toxic regimens. Anti-EGFR therapy in combination with chemotherapy is necessary to achieve the best clinical outcomes.

Conclusion:

Future prospective studies on the identification of additional biological agents and novel anti-EGFR agents are warranted.

High-Resolution Ex Vivo Elastography to Characterize Tumor Stromal Heterogeneity In Situ in Pancreatic Adenocarcinoma

OBJECTIVE

Tumor stiffening in pancreatic adenocarcinoma (PDAC) has been linked to cancer progression and lack of therapy response, yet current elastography tools cannot map stiffness in a whole tumor field-of-view with biologically relevant spatial resolution. Therefore, this study was developed to assess stiffness heterogeneity and geometrical patterns across whole PDAC xenograft ex vivo tumors.

METHODS

The ex vivo elastography (EVE) mapping system was capable of creating stiffness map at 300-micron spatial resolution under a 5-20 mm field of view relevant to whole tumor assessment. The stiffness value at each location was determined by compression testing and an absolute tumor Young's modulus map was calculated based on the calibration between the system and ultrasound elastography (R² = 0.95).

RESULTS

Two PDAC tumor lines AsPC-1 and BxPC-3 implanted in xenograft models were assessed to show tumor stiffness and its linear relationship to collagen content (R² = 0.59). EVE was able to capture stiffness heterogeneity ranging between 5 and 100 kPa in pancreatic tumors with collagen content up to 25%. More importantly, data shows the inverse relationship of local stiffness to local drug distribution (R² = 0.66) and vessel patency (R² = 0.61) in both PDAC tumor lines.

CONCLUSION

The results suggested that elastography could be utilized to predict drug penetration in PDAC tumors or assess response to biological modifying adjunct therapies.

SIGNIFICANCE

This study presents the first attempt to map out stiffness on a biologically relevant spatial scale across whole PDAC tumor slices with spatial resolution in the hundreds of microns.

Genomic profiling in pancreatic ductal adenocarcinoma and a pathway towards therapy individualization: A scoping review

CONTEXT

Pancreatic cancer (PDAC) is one of the most challenging cancers to treat with modest recent improvements in survival from new systemic therapies. There is growing interest in individualized therapy underpinned by somatic and germline genomic alterations.

OBJECTIVE

A systematic review of data on therapies targeting somatic and germline alterations, and their downstream pathways in PDAC.

METHOD

A systematic literature search was conducted using PRISMA guidelines to include relevant results published after January 1, 2008.

RESULTS

A total of 71 relevant studies were included. We identified 36 studies targeting the KRAS-pathway, the most common being with MEK-inhibitor therapy. Twenty-two studies were identified that evaluated platinum-based chemotherapy and PARP inhibitors in patients with deleterious mutations in DNA damage repair genes and have shown encouraging results. Immunotherapy has demonstrated activity in patients with mismatch repair deficiency/microsatellite instability.

CONCLUSION

Evidence from translational and clinical research presents an exciting platform for genomic targeted therapy in PDAC. Validity for targeting BRCA with platinum and PARP inhibitors and microsatellite instability with immune therapy has been established, nonetheless, evidence for targeting the common driver oncogenes is lacking and much work is needed. Of importance is identifying the subgroup of KRAS -wild type PDAC (approximately 5%) where there is enrichment for targetable opportunities.

Pharmacotherapeutic strategies for treating pancreatic cancer: advances and challenges

INTRODUCTION

Despite many efforts to improve the outcome of pancreatic ductal adenocarcinoma (PDAC), its prognosis remains poor, which is mostly related to late diagnosis and drug resistance. Improving systemic therapy is considered the major challenge in improving the outcome of this disease.

AREAS COVERED

This review covers novel chemotherapy and targeted agents in the treatment of PDAC, with a focus on advanced stage disease.

EXPERT OPINION

Current frontline therapies used in the treatment of patients with PDAC with favorable performance status are gemcitabine (GEM) and nab-paclitaxel or 5-fluorouracil, leucovorin, irinotecan, and oxaliplatin (FOLFIRINOX). PDAC has a number of genetic mutations that may explain its biological behavior, such as KRAS, p53 and CDK2NA, which occur in more than 90% of cases. Unfortunately, to this day, a specific targeting agent to any of those frequent gene mutations is lacking. Emerging areas of targeted therapies include the DNA repair, stroma, metabolism, and stem cells. Immunotherapy with either vaccines or immune checkpoint inhibitors has not produced any significant improvements in outcome of PDAC. Incorporating different approaches in therapy, including conventional, immunological, and others, is key in offering patients with the best possible care.

Evaluation of the Insulin-like Growth Factor Receptor Pathway in Patients with Advanced Breast Cancer Treated with Trastuzumab

BACKGROUND

Trastuzumab is a monoclonal antibody against HER2-positive breast cancer. Despite improving the natural history of the disease, there is a number of patients who are resistant to it, whereas all patients will eventually develop resistance and disease will progress. Inconsistent preclinical data show that the IGF-R pathway may contribute to either de novo or acquired resistance to trastuzumab.

MATERIALS AND METHODS

In total, 227 trastuzumab-treated metastatic breast cancer patients were evaluated for IGF-1, IGF-1R, GLP-1R, Akt1, Akt2 Akt3 mRNA expression, and IGF-1Rα, IGF-1Rβ, IGF-2R protein expression.

RESULTS

Only 139 patients were truly HER2-positive by central assessment. Among HER2-positive patients, high Akt2 and GLP-1R mRNA expression showed a trend towards higher and lower risk of progression, respectively (HR=1.83, 95%CI=0.90-3.72, p=0.094 and HR=0.62, 95%CI=0.36-1.06, p=0.079), while high Akt1 and GLP-1R mRNA expression presented a trend towards unfavorable survival (HR=1.67, 95%CI=0.93-2.99, p=0.086 and HR=1.67, 95%CI=0.94-2.96, p=0.080). Among HER2-negative patients, high GLP-1R mRNA expression and negative stromal IGF-1Rβ protein expression showed a trend towards worse survival (HR=2.31, 95%CI=0.87-6.13, p=0.094 and HR=2.03, 95%CI=0.94-4.35, p=0.071, respectively). In the multivariate analyses, HER2-positive patients with high Akt1 and GLP-1R mRNA expression had a worse survival (HR=1.86, 95%CI=1.01-3.43, p=0.045 and HR=1.83, 95%CI=0.99-3.41, p=0.055, respectively).

CONCLUSION

This study revealed a crosstalk between the IGF-R pathway and HER2. There was evidence that high Akt1 and GLP-1R mRNA expression might affect survival among HER2-positive metastatic breast cancer patients treated with trastuzumab.

Effect of arenobufagin on human pancreatic carcinoma cells

Pancreatic carcinoma (PC) is a deadly form of cancer with poor overall survival. Currently, chemotherapy such as gemcitabine and 5-fluorouracil (5-FU) are the most popular medications that can improve survival, but rapid drug-resistance makes the search for more effective drugs urgent. Upon looking for natural components to treat PC, it was found that arenobufagin, a cardiac glycosides-like compound, showed significant effects on the gemcitabine-resistant pancreatic carcinoma cell line Panc-1 and the gemcitabine-sensitive cell line ASPC-1 at nanomolar concentrations. The present study used MTT and clonogenic survival assays to examine survival and proliferation, and western blotting to assess changes in the associated mitogen activated protein kinase and phosphoinositide 3-kinase pathways and expression of apoptosis-related proteins. The current study also detected the cell cycle by flow cytometry. Arenobufagin inhibited cell survival and proliferation, decreased the phosphorylation of key downstream proteins of K-Ras, including protein kinase B and extracellular signal related kinase, induced cell cycle G2/M phase arrest and apoptosis, and downregulated the level of phosphorylated epidermal growth factor receptor. Notably, the present data also showed that arenobufagin can enhance the sensitivity of PC cells to gemcitabine and 5-FU. In conclusion, arenobufagin could enhance the effect of gemcitabine and 5-FU on PC cells by targeting multiple key proteins. Therefore, arenobufagin has potential as anadjuvant therapy for the treatment of PC.

Pancreatic Ductal Adenocarcinoma: Current and Evolving Therapies

Pancreatic ductal adenocarcinoma (PDAC), which constitutes 90% of pancreatic cancers, is the fourth leading cause of cancer-related deaths in the world. Due to the broad heterogeneity of genetic mutations and dense stromal environment, PDAC belongs to one of the most chemoresistant cancers. Most of the available treatments are palliative, with the objective of relieving disease-related symptoms and prolonging survival. Currently, available therapeutic options are surgery, radiation, chemotherapy, immunotherapy, and use of targeted drugs. However, thus far, therapies targeting cancer-associated molecular pathways have not given satisfactory results; this is due in part to the rapid upregulation of compensatory alternative pathways as well as dense desmoplastic reaction. In this review, we summarize currently available therapies and clinical trials, directed towards a plethora of pathways and components dysregulated during PDAC carcinogenesis. Emerging trends towards targeted therapies as the most promising approach will also be discussed.

Emerging protein kinase inhibitors for treating pancreatic cancer

INTRODUCTION

Pancreatic cancer, the incidence and mortality of which are increasing around the world, has the most dismal prognosis among the commonly encountered cancers. Systemic chemotherapy plays an important role in the treatment of patients with pancreatic cancer, and development of more effective chemotherapies is being sought. Areas covered: This review article provides a summary about protein kinase inhibitors that have been investigated for the treatment of pancreatic cancer, not only existing agents targeting RAS, EGFR, VEGFR, MEK, etc., but also various compounds targeting, including the MAPK, PI3 K/Akt/mTOR, and JAK/STAT signaling pathways, trials of which are currently ongoing. To date, none has shown sufficient efficacy as to merit becoming established as a standard treatment agent for pancreatic cancer. Expert opinion: As the toxicities of protein kinase inhibitors usually differ from those of cytotoxic agents, it could be of value to use these agents in combination with gemcitabine plus nab-paclitaxel. It may be reasonable to identify a suitable disease and/or predictive markers for new compounds in proof of concept trials. It is an urgent need to conduct phase III trials, on the basis of the results obtained, in subpopulations with biomarkers to predict the efficacy of these drugs.

Available technologies and clinical applications of targeted chemotherapy in pancreatic cancer

The incidence of pancreatic cancer, the fourth leading cause of cancer death in United States, is increasing worldwide. Even though the cure rate has doubled in 40 years, it is abysmally poor at 6-7%. As surgical resection remains the only curative treatment and less than 20% of the newly diagnosed cancers are resectable, the major burden of disease management lies in early diagnosis, good prognostication, and proper neo-adjuvant and/or adjuvant therapy. With advancing technologies and their ease of availability, researchers have better tools to understand pancreatic cancer. In the post-genetic era, proteomic, phosphoproteomic, metabolomic, and more have brought us to a multi-omics era. These newer avenues bring promises of better screening modalities, less invasive diagnostics and monitoring, subtyping of pancreatic cancer, and fine tuning the treatment modalities not only to the right stage of tumor but also to the right tumor biology. As the multitudes of technologies are generating extensive amounts of incongruous data, they are giving clinicians a lot of non-actionable information. In this paper, we wish to encompass the newer technologies, sub-classifications, and future treatment modalities in personalized care of patients with pancreatic cancer.

Pancreatic Cancer from Molecular Pathways to Treatment Opinion

Pancreatic cancer is considered one of the most lethal malignances. It has been observed that the five year survival rate is less than 5%. Early diagnosis, understanding the risk factors and investigation of the molecular pathways with targeted therapy are the keys for efficient treatment. Moreover; there are several local treatments for patients with unresectable pancreatic cancer. There are several combined therapies with chemotherapy and radiotherapy, however; a local therapy approach for many patients with poor performance status are in need. For those patients with good performance status new polychemotherapy regimens are used with success and increased survival improvement. Polychemotherapy has been observed to increase the rate of radical resections in some cases. Second line therapy is used for patients with good performance status and metastatic disease. Oxaliplatin-based regimens are mostly used, however; there are several other drugs that are being developed. Unfortunately, targeted therapy has not presented the expected efficiency. Moreover; immunotherapy; another treatment approach for several cancers types has again failed to present positive results for pancreatic cancer. In the current mini review, we will present information from the diagnosis to molecular pathways and targeted treatment.

K-Ras mutation detection in liquid biopsy and tumor tissue as prognostic biomarker in patients with pancreatic cancer: a systematic review with meta-analysis

K-Ras gene mutations have been found in most pancreatic cancers; however, conflicting data on the prognostic value of K-Ras mutations in pancreatic cancer have been published. We conducted a meta-analysis to assess its prognostic significance. Literature searches of PubMed, EMBASE, Cochrane Library, Web of Science and Google Scholar were performed through December 2015 to identify publications exploring the association of K-Ras mutation with overall survival. Forty eligible studies involving 3427 patients with pancreatic cancer were included in the present meta-analysis. Our analysis showed a hazard ratio (HR) of negative association with survival of 1.61 [95 % confidence interval (CI) 1.36-1.90; p < 0.01] in K-Ras mutant pancreatic cancer patients. In subgroup analyses, K-Ras mutations detected in tumor tissues and in liquid biopsies had HRs of 1.37 (95 % CI 1.20-1.57; p < 0.01) and 3.16 (95 % CI 2.1-4.71; p < 0.01), respectively. In addition, the HR was higher when K-Ras mutations were detected in fresh frozen samples (HR = 2.01, 95 % CI 1.28-3.16, p = 0.002) than in formalin-fixed, paraffin-embedded (FFPE) samples (HR = 1.29, 95 % CI 1.12-1.49, p < 0.01). Though K-Ras alterations are more frequent among non-East Asian individuals than East Asian individuals, there were no significant differences in HRs of survival between the two ethnic subgroups. In conclusion, this meta-analysis suggests that K-Ras mutations are associated with a worse overall survival in pancreatic cancer patients, especially when mutations are detected in liquid biopsies or fresh frozen tumor tissue samples.

Pancreatic cancer from bench to bedside: molecular pathways and treatment options

In the last forty years the pancreatic cancer treatment has made advances, however; still novel drugs are needed. It is known that the five year survival rate remains around 5%. The best treatment option still remains surgery, if patients are diagnosed early. In the last decade the biology of pancreatic cancer has been vastly explored and novel agents such as; tyrosine kinase agents, or vaccines have been added as a treatment perspective. The big challenge is now to translate this knowledge in better outcomes for patients. In this current review we will present information from pancreatic cancer diagnosis to molecular pathways and treatment options; current and future.

State of the art biological therapies in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal malignancies with a five-year survival rate of approximately 5%. Several target agents have been tested in PDAC, but almost all have failed to demonstrate efficacy in late phase clinical trials, despite the better understanding of PDAC molecular biology generated by large cancer sequencing initiatives in the past decade. Eroltinib (a small-molecule tyrosine-kinase inhibitor of epidermal growth factor receptor) plus gemcitabine is the only schedule with a biological agent approved for advanced pancreatic cancer, but it has resulted in a very modest survival benefit in unselected patients. In our work, we report a summary of the main clinical trials (closed and ongoing) that refer to biological therapy evaluation in pancreatic cancer treatment.

Promising new therapies in advanced pancreatic adenocarcinomas

Pancreatic ductal adenocarcinoma is a lethal disease due to late diagnosis, early metastasis and the lack of effective therapies. In patients with metastatic disease, 1-year survival ranges from 17 to 23% and 5-year survival is less than 5%. This necessitates an urgent need for developing more effective therapies. Targeting the neoplastic cells has been largely ineffective due to the dense stroma, which is a physical barrier for effective drug delivery and also a source for different factors that promote tumor progression and immunosuppression. In this review, we focus on understanding the complex biology of this tumor as it relates to the evaluation of previously failed molecularly targeted trials and review potential new therapies that are emerging in the treatment of metastatic pancreatic ductal adenocarcinoma.

Progress in pancreatic cancer therapeutics: The potential to exploit molecular targets

Pancreatic ductal adenocarcinoma is an aggressive and devastating disease associated with poor survival outcomes. Even though significant advances have been made towards understanding the intricate pathology of this cancer, several important aspects remain unknown. Recently, key genetic mutations within the tumour have been identified, but the exact role they play in tumourigenesis has yet to be determined. For many years, the micro-tumour environment and stroma was thought to aid proliferation but there is now emerging research that suggests the contrary. Several novel targeted agents in pre-clinical and early clinical studies have been promising but it remains to be seen whether they will have a significant impact on patient outcomes. In this review we discuss the unique nature of pancreatic cancer biology, current treatment options and summarise the latest results from pre-clinical and clinical research. We also discuss the future strategies that are needed to improve outcomes for this disease.

Response to GEMOX plus erlotinib in pancreatic cancer is associated with ERCC1 overexpression

INTRODUCTION

There are no data about the efficacy of gemcitabine in combination with oxaliplatin (GEMOX) and erlotinib for the treatment of metastatic pancreatic cancer (mPC). Thus, we performed this retrospective analysis in mPC patients to investigate the activity and safety of GEMOX plus erlotinib and correlated the benefit with ERCC1 expression, a potential biomarker for treatment response.

PATIENTS AND METHODS

Patients with untreated mPC receiving off-protocol GEMOX plus erlotinib were included. Data collection included baseline demographic, response and toxicity data as well as PFS and OS. Additionally, immunohistochemistry was performed to stain for ERCC1 expression.

RESULTS

A total of 51 patients were included. The median age was 62 years and the median ECOG performance score was 1 (range, 0-1). Objective response or disease stabilization was achieved in 54% of the patients. The median PFS was 4·4 months (95% CI 4·4-5·4) and median OS was 8·5 months (95% CI 6·1-10·9). The 27 patients, who benefited from this regimen, had a median PFS of 6·7, a median OS of 11·2 months and an overexpression of ERCC1 (histoscore 10, P ≤ 0·05) compared to nonresponders (histoscore 7·2). Myelosuppression was the most frequent side effect. The most common severe nonhematological toxicities were diarrhoea and skin toxicity in six (12%) patients each.

CONCLUSIONS

These data suggest that the combination of GEMOX plus erlotinib is safe and active in about half of the patients. Patients, who had a higher ERCC1 staining pattern, benefited most from this therapy. Prospective biomarker studies are warranted to confirm these findings.

Targeted therapy in gastrointestinal malignancies

Increased understanding of cancer pathogenesis has identified several pathways that serve as potential targets for novel targeted agents in development. The selection of targeted cancer therapy based on biomarkers has instigated a new era of personalized medicine and changed the way we practice oncology. Many targeted agents are approved for treatment of gastrointestinal malignancies most targeting tumor angiogenesis, and many more are in different phases of development. Here we briefly summarize nine different targeted agents that are approved currently in the U.S. and several other agents currently being studied in various gastrointestinal cancers.

Targeting the Ras-ERK pathway in pancreatic adenocarcinoma

Pancreatic ductal adenocarcinoma (PAC) stands as the poorest prognostic tumor of the digestive tract with limited therapeutic options. PAC carcinogenesis is associated with the loss of function of tumor suppressor genes such as INK4A, TP53, BRCA2, and DPC4, and only a few activated oncogenes among which K-RAS mutations are the most prevalent. The K-RAS mutation occurs early in PAC carcinogenesis, driving downstream activation of MEK and ERK1/2 which promote survival, invasion, and migration of cancer cells. In PAC models, inhibition of members of the Ras-ERK pathway blocks cellular proliferation and metastasis development. As oncogenic Ras does not appear to be a suitable drug target, inhibitors targeting downstream kinases including Raf and MEK have been developed and are currently under evaluation in clinical trials. In this review, we describe the role of the Ras-ERK pathway in pancreatic carcinogenesis and as a new therapeutic target for the treatment of PAC.

Erlotinib, gefitinib, and vandetanib inhibit human nucleoside transporters and protect cancer cells from gemcitabine cytotoxicity

PURPOSE

Combinations of tyrosine kinase inhibitors (TKI) with gemcitabine have been attempted with little added benefit to patients. We hypothesized that TKIs designed to bind to ATP-binding pockets of growth factor receptors also bind to transporter proteins that recognize nucleosides.

EXPERIMENTAL DESIGN

TKI inhibition of uridine transport was studied with recombinant human (h) equilibrative (E) and concentrative (C) nucleoside transporters (hENT, hCNT) produced individually in yeast. TKIs effects on uridine transport, gemcitabine accumulation, regulation of hENT1 activity, and cell viability in the presence or absence of gemcitabine were evaluated in human pancreatic and lung cancer cell lines.

RESULTS

Erlotinib, gefitinib and vandetanib inhibited [(3)H]uridine transport in yeast and [(3)H]uridine and [(3)H]gemcitabine uptake in the four cell lines. Treatment of cell lines with erlotinib, gefitinib, or vandetanib for 24 hours reduced hENT1 activity which was reversed by subsequent incubation in drug-free media for 24 hours. Greater cytotoxicity was observed when gemcitabine was administered before erlotinib, gefitinib, or vandetanib than when administered together and synergy, evaluated using the CalcuSyn Software, was observed in three cell lines resulting in combination indices under 0.6 at 50% reduction of cell growth.

CONCLUSIONS

Vandetanib inhibited hENT1, hENT2, hCNT1, hCNT2, and hCNT3, whereas erlotinib inhibited hENT1 and hCNT3 and gefitinib inhibited hENT1 and hCNT1. The potential for reduced accumulation of nucleoside chemotherapy drugs in tumor tissues due to inhibition of hENTs and/or hCNTs by TKIs indicates that pharmacokinetic properties of these agents must be considered when scheduling TKIs and nucleoside chemotherapy in combination.

Molecularly targeted therapies in metastatic pancreatic cancer: a systematic review

Pancreatic cancer is the fourth leading cause of cancer-related death. Most patients present with an advanced stage of disease that has a dismal outcome, with a median survival of approximately 6 months. Evidently, there is a clear need for the development of new agents with novel mechanisms of action in this disease. A number of biological agents modulating different signal transduction pathways are currently in clinical development, inhibiting angiogenesis and targeting epidermal growth factor receptor, cell cycle, matrix metalloproteinases, cyclooxygenase-2, mammalian target of rapamycin, or proteasome. This is the first systematic review of the literature to synthesize all available data coming from trials and evaluate the efficacy and safety of molecular targeted drugs in unresectable and metastatic pancreatic cancer. However, it should be stressed that although multiple agents have been tested, only 9 phase 3 trials have been conducted and one agent (erlotinib) has been approved by the Food and Drug Administration for use in clinical practice. As knowledge accumulates on the molecular mechanisms underlying carcinogenesis in the pancreas, the anticipated development and assessment of molecularly targeted agents may offer a promising perspective for a disease which, to date, remains incurable.

Topoisomerase II alpha gene amplification is a favorable prognostic factor in patients with HER2-positive metastatic breast cancer treated with trastuzumab

BACKGROUND

The vast majority of patients with HER2-positive metastatic breast cancer (MBC) treated with trastuzumab eventually develop resistance to this agent. There is an unmet need therefore, for identifying biological markers with possible prognostic/predictive value in such patients. The aim of this study was to investigate the prognostic role of topoisomerase II alpha gene (TOP2A) amplification and protein (TopoIIa) expression in patients treated with trastuzumab-containing regimens.

METHODS

Formalin-fixed paraffin-embedded tumor tissue samples were retrospectively collected from 225 eligible patients treated with trastuzumab. Protein expression of ER, PgR, Ki67, PTEN, HER2 and TopoIIa were centrally assessed by immunohistochemistry. HER2 and TOP2A gene amplification was evaluated by fluorescence in situ hybridization. PIK3CA mutations were identified by single nucleotide polymorphism genotyping. Survival was evaluated from the initiation of trastuzumab as 1st line treatment to the date of last follow-up or death.

RESULTS

Among the 225 samples analyzed, only 137 (61%) were found to be HER2-positive. TOP2A was amplified in 41% and deleted in 16% of such tumors. TOP2A gene amplification was more frequent in ER-negative tumors. TopoIIa protein expression was observed in the majority (65%) of the samples and was associated with ER-positive status, high Ki67 expression, presence of PTEN protein and PIK3CA mutations. Median follow-up for patients treated in the 1st line was 51 months. Survival was more prolonged with trastuzumab-containing treatment in HER2-positive patients (50 months, log-rank, p=0.007). TOP2A non-amplified or deleted tumors were associated with increased risk for death compared to TOP2A amplified tumors (HR=2.16, Wald's p=0.010 and HR=2.67, p=0.009, respectively). In multivariate analysis, a significant interaction of TOP2A with anthracycline treatment (either in the adjuvant or the 1st line setting) was observed for survival (Wald's p=0.015). Among the TOP2A amplified subgroup, anthracycline-treated patients were associated with decreased risk for death.

CONCLUSIONS

TOP2A gene amplification was shown to be a favorable prognostic marker in HER2-positive MBC patients treated with trastuzumab, such an effect however, appears to rather be related to treatment with anthracyclines (predictive marker for benefit from anthracyclines). The results of the present retrospective study warrant validation in larger cohorts of patients treated in the context of randomized trials.

Dual ErbB1 and ErbB2 receptor tyrosine kinase inhibition exerts synergistic effect with conventional chemotherapy in pancreatic cancer

Patient survival in pancreatic cancer remains poor with gemcitabine (GEM)-based regimens. The target specific molecular agent lapatinib, a dual ErbB1 and ErbB2 receptor tyrosine kinase inhibitor, has shown significant activity against ErbB1 and ErbB2-expressing tumors. Since pancreatic tumors frequently overexpress these proteins, we investigated its effects, both alone and in conjunction with 5-FU or GEM. The pancreatic cancer cell lines PANC-1 and AsPC were treated with varying doses of lapatinib in vitro. The effects on ErbB1/ErbB2 protein phosphorylation and on the cell survival protein survivin were determined by western blotting. Cytotoxicity was determined by MTT assay and apoptosis was measured using the caspase-3 colorimetric assay. Similar dose-response lapatinib experiments were conducted with varying concentrations of 5-FU or GEM and isobolograms were constructed to evaluate therapeutic synergy. Lapatinib inhibited protein phosphorylation in the range of 4-16 µM, a clinically achievable concentration. The lapatinib-treated cells showed a dose-dependent inhibition of cell proliferation and induction of apoptosis at the same concentrations that blocked ErbB1/ErbB2 phosphorylation. The addition of 5-FU or GEM to these cells resulted in synergistic effects. The lapatinib-treated cells also demonstrated downregulation of survivin. Simultaneous dual ErbB1 and ErbB2 receptor tyrosine kinase inhibition with lapatinib results in significant reduction of pancreatic cancer cell growth and proliferation. These effects occur at clinically achievable concentrations and are synergistic with the effects of 5-FU or GEM. These findings support the potential role of lapatinib in the treatment of pancreatic cancer.

Screening for EGFR Mutations in Patients with Head and Neck Cancer Treated with Gefitinib on a Compassionate-Use Program: A Hellenic Cooperative Oncology Group Study

Background and Aim. EGFR is commonly expressed in cancers of the head and neck (H and N), and anti-EGFR agents have demonstrated improvements in outcomes (TTP and OS). The aim of this study was to determine EGFR gene status in H and N cancer patients treated with gefitinib and to correlate mutational status with clinico-pathological data and response. Patients and Methods. Patients with histologically confirmed H and N cancer having failed prior treatment for advanced disease entered this compassionate-use-program. Nineteen patients received gefitinib. EGFR expression was assessed by IHC, gene copy number by FISH, and mutation analysis was conducted for EGFR (18-21), KRAS, BRAF (V600E), and HER-2 exon 20. An additional TKI naive cohort of 73 patients was also screened. Results. Mutations were detected in 6/19 patients (3× EGFR, 1× KRAS, and 2× HER2-exon 20). There were no significant differences in TTP or OS for patients with somatic EGFR mutations. No BRAF mutations were detected. Conclusions. The incidence of EGFR mutations in H and N cancer in this study was 5.3%. No statistically relevant correlations between mutation or gene gain and response or survival were observed. Due to the limited number of patients and low incidence of genetic aberrations in the genes analyzed, additional studies are warranted.

The molecular targets for the diagnosis and treatment of pancreatic cancer

Pancreatic cancer is considered an aggressive malignancy that responds poorly to current treatments and therefore has a dismal survival rate. This disease is usually not diagnosed until a late stage, at which point palliative chemotherapy with the purine analogue gemcitabine and/or a fluoropyrimidine or a platinum agent is the standard approach. There are some new data on the molecular and genetic changes that take place in pancreatic cancer, which may facilitate the accuracy of diagnosis and efficacy of treatments. However, translational efforts in clinical practice have increased clinicians' options with a targeted agent, erlotinib, in combination with the standard gemcitabine chemotherapy. Many other novel drugs currently being tested in the field of pharmaco-oncology target various altered biological pathways and molecules. Nevertheless, the lack of clinically significant improvements in treatments is rendering efforts to develop methods of early diagnosis both more urgent and promising. The aim of this review was to summarize the molecular basis of pancreatic carcinogenesis and the latest developments in diagnosis by molecular means, focusing on the results of clinical research into targeted and personalized treatments.

Oncogenic mutant forms of EGFR: lessons in signal transduction and targets for cancer therapy

The EGF-receptor is frequently mutated in a large variety of tumors. Here we review the most frequent mutations and conclude that they commonly enhance the intrinsic tyrosine kinase activity, or they represent loss-of-function of suppressive regulatory domains. Interestingly, the constitutive activity of mutant receptors translates to downstream pathways, which are subtly different from those stimulated by the wild-type receptor. Cancer drugs intercepting EGFR signaling have already entered clinical application. Both kinase inhibitors specific to EGFR, and monoclonal antibodies to the receptor are described, along with experimental approaches targeting the HSP90 chaperone. Deeper understanding of signaling pathways downstream to mutant receptors will likely improve the outcome of current EGFR-targeted therapies, as well as help develop new drugs and combinations.

Pancreatic cancer: pathobiology, treatment options, and drug delivery

Pancreatic cancer is the fourth leading cause of cancer-related deaths in the USA. The high mortality rate is partly due to lack of effective treatments. This review summarizes the pathobiology and current treatment options for pancreatic cancer. Moreover, the review discusses the opportunities of developing novel therapies for pancreatic cancer provided by the progress in understanding the genetic mutations, tumor microenvironment, cancer stem cells, and drug delivery.

MMP9 but Not EGFR, MET, ERCC1, P16, and P-53 Is Associated with Response to Concomitant Radiotherapy, Cetuximab, and Weekly Cisplatin in Patients with Locally Advanced Head and Neck Cancer

Concomitant administration of radiotherapy with cisplatin or radiotherapy with cetuximab appear to be the treatment of choice for patients with locally advanced head and neck cancer. In the present retrospective analysis, we investigated the predictive role of several biomarkers in an unselected cohort of patients treated with concomitant radiotherapy, weekly cisplatin, and cetuximab (CCRT). We identified 37 patients treated with this approach, of which 13 (35%) achieved a complete response and 10 (27%) achieved a partial response. Severe side effects were mainly leucopenia, dysphagia, rash, and anemia. Tumor EGFR, MET, ERCC1, and p-53 protein and/or gene expression were not associated with treatment response. In contrast, high MMP9 mRNA expression was found to be significantly associated with objective response. In conclusion, CCRT is feasible and active. MMP9 was the only biomarker tested that appears to be of predictive value in cetuximab treated patients. However, this is a hypothesis generating study and the results should not be viewed as definitive evidence until they are validated in a larger cohort.

Emerging drugs in the treatment of pancreatic cancer

BACKGROUND

Pancreatic cancer is the fourth leading cause of cancer-related death in the US. However, there is a growing belief that novel biological agents could improve survival of patients with this cancer. Gemcitabine-based chemotherapy remains the cornerstone treatment for advanced pancreatic cancers. So far, the current targeted agents that have been used in combination with gemcitabine have failed to improve clinical outcomes. This failure may stem from the heterogeneous molecular pathogenesis of pancreatic cancers, which involves several oncogenic pathways and defined genetic mutations.

OBJECTIVE

The aims of this review are: i) to define the existing treatments available at present for patients with pancreatic cancers in the neo-adjuvant, adjuvant, locally advanced and metastatic settings; ii) to highlight the molecular heterogeneity of the cancers and the rationale for targeting specific oncogenic pathways; iii) to give an overview of targeted agents that may potentially have an impact in the treatment of pancreatic cancers.

CONCLUSIONS

Molecular pathogenesis of pancreatic cancer involves several pathways and defined genetic mutations. Targeting these complex molecular pathways with a combination of novel biological and chemotherapeutic agents could potentially improve patient outcome.

Pancreatic cancer: molecular pathogenesis and new therapeutic targets

Patients with pancreatic cancer normally present with advanced disease that is lethal and notoriously difficult to treat. Survival has not improved dramatically despite routine use of chemotherapy and radiotherapy; this situation signifies an urgent need for novel therapeutic approaches. Over the past decade, a large number of studies have been published that aimed to target the molecular abnormalities implicated in pancreatic tumor growth, invasion, metastasis, angiogenesis and resistance to apoptosis. This research is of particular importance, as data suggest that a large number of genetic alterations affect only a few major signaling pathways and processes involved in pancreatic tumorigenesis. Although laboratory results of targeted therapies have been impressive, until now only erlotinib, an epidermal growth factor receptor tyrosine kinase inhibitor, has demonstrated modest survival benefit in combination with gemcitabine in a phase III clinical trial. Whilst the failures of targeted therapies in the clinical setting are discouraging, lessons have been learnt and new therapeutic targets that hold promise for the future management of the disease are continuously emerging. This Review describes some of the important developments and targeted agents for pancreatic cancer that have been tested in clinical trials.