Lack of growth inhibitory synergism with combined MAPK/PI3K inhibition in preclinical models of pancreatic cancer

Targeting KRAS in Pancreatic Ductal Adenocarcinoma: The Long Road to Cure

Pancreatic ductal adenocarcinoma (PDAC) remains an important cause of cancer-related mortality, and it is expected to play an even bigger part in cancer burden in the years to come. Despite concerted efforts from scientists and physicians, patients have experienced little improvement in survival over the past decades, possibly because of the non-specific nature of the tested treatment modalities. Recently, the discovery of potentially targetable molecular alterations has paved the way for the personalized treatment of PDAC. Indeed, the central piece in the molecular framework of PDAC is starting to be unveiled. KRAS mutations are seen in 90% of PDACs, and multiple studies have demonstrated their pivotal role in pancreatic carcinogenesis. Recent investigations have shed light on the differences in prognosis as well as therapeutic implications of the different KRAS mutations and disentangled the relationship between KRAS and effectors of downstream and parallel signaling pathways. Additionally, the recognition of other mechanisms involving KRAS-mediated pathogenesis, such as KRAS dosing and allelic imbalance, has contributed to broadening the current knowledge regarding this molecular alteration. Finally, KRAS G12C inhibitors have been recently tested in patients with pancreatic cancer with relative success, and inhibitors of KRAS harboring other mutations are under clinical development. These drugs currently represent a true hope for a meaningful leap forward in this dreadful disease.

Potential drug-drug interactions with mitogen-activated protein kinase (MEK) inhibitors used to treat melanoma

INTRODUCTION

The management of patients with BRAF-mutated advanced melanoma who are undergoing targeted therapy with MEK inhibitors can be complicated by the co-administration of multiple medications, which can give rise to drug-drug interactions of clinical significance.

COVERED AREAS

Our review presents a comprehensive analysis of the pharmacokinetic and pharmacodynamic interactions of the three approved for advanced melanoma MEK inhibitor drugs - binimetinib, cobimetinib, and trametinib. MEDLINE (PubMed) was utilized for the literature search, comprising clinical studies, observational studies, and preclinical research. The review discusses the impact of these interactions on efficacy and safety of the treatments and differentiates between interactions supported by pharmacokinetic or pharmacodynamic mechanisms, those encountered in clinical practice, and those observed in preclinical studies.

EXPERT OPINION

Physicians should be aware about potential benefits, but also increased toxicity caused by drug interactions between MEK inhibitors and other drugs in the management of patients with metastatic melanoma.

Prospects of targeting PI3K/AKT/mTOR pathway in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) has one of the worst prognoses among all malignancies. PI3K/AKT/mTOR signaling pathway, a main downstream effector of KRAS is involved in the regulation of key hallmarks of cancer. We here report that whole-genome analyses demonstrate the frequent involvement of aberrant activations of PI3K/AKT/mTOR pathway components in PDAC patients and critically evaluate preclinical and clinical evidence on the application of PI3K/AKT/mTOR pathway targeting agents. Combinations of these agents with chemotherapeutics or other targeted therapies, including the modulators of cyclin-dependent kinases, receptor tyrosine kinases and RAF/MEK/ERK pathway are also examined. Although human genetic studies and preclinical pharmacological investigations have provided strong evidence on the role of PI3K/AKT/mTOR pathway in PDAC, clinical studies in general have not been as promising. Patient stratification seems to be the key missing point and with the advent of biomarker-guided clinical trials, targeting PI3K/AKT/mTOR pathway could provide valuable assets for treatment of pancreatic cancer patients.

KRAS wild-type pancreatic ductal adenocarcinoma: molecular pathology and therapeutic opportunities

Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease, whose main molecular trait is the MAPK pathway activation due to KRAS mutation, which is present in 90% of cases.The genetic landscape of KRAS wild type PDAC can be divided into three categories. The first is represented by tumors with an activated MAPK pathway due to BRAF mutation that occur in up to 4% of cases. The second includes tumors with microsatellite instability (MSI) due to defective DNA mismatch repair (dMMR), which occurs in about 2% of cases, also featuring a high tumor mutational burden. The third category is represented by tumors with kinase fusion genes, which marks about 4% of cases. While therapeutic molecular targeting of KRAS is an unresolved challenge, KRAS-wild type PDACs have potential options for tailored treatments, including BRAF antagonists and MAPK inhibitors for the first group, immunotherapy with anti-PD-1/PD-L1 agents for the MSI/dMMR group, and kinase inhibitors for the third group.This calls for a complementation of the histological diagnosis of PDAC with a routine determination of KRAS followed by a comprehensive molecular profiling of KRAS-negative cases.

NGF from pancreatic stellate cells induces pancreatic cancer proliferation and invasion by PI3K/AKT/GSK signal pathway

Pancreatic cancer (PC) is a continuously high lethal disease, and the tumour microenvironment plays a pivotal role during PC progression. Herein, we focus on that the Nerve growth factor (NGF)/Tropomyosin-related kinase A (TrkA), in pancreatic stellate cells-pancreatic cancer cells (PSCs-PC cells) co-culture system, influences PC proliferation and invasion. The model of PC cells and PSCs was directly co-cultured in a no-touch manner, using the Transwell as the co-culture system. NGF and TrkA expression was measured in cultured system by real-time PCR, immunofluorescence, Western blotting analysis or ELISA. Small interfering RNA transfection was used to regulate the expression of TrkA in PC cells. The promotion of cancer invasion was investigated using Matrigel Transwell assay. In our study, NGF/TrkA is overexpressed in PSCs-PC cells co-culture system and promotes the invasion and proliferation of PC cells. And the epithelial-mesenchymal transition-related genes are influenced by si-TrkA. What's more, NGF/TrkA regulates the PC cell proliferation and invasion via activation of PI3K/AKT/GSK signalling. The present study demonstrated NGF/TrkA promoted the PC cell proliferation and invasion in the co-culture system by the activation of the PI3K/AKT/GSK signal cascade, providing a potential therapeutic target for PC patients.

From Genetic Alterations to Tumor Microenvironment: The Ariadne's String in Pancreatic Cancer

The threatening notoriety of pancreatic cancer mainly arises from its negligible early diagnosis, highly aggressive progression, failure of conventional therapeutic options and consequent very poor prognosis. The most important driver genes of pancreatic cancer are the oncogene KRAS and the tumor suppressors TP53, CDKN2A, and SMAD4. Although the presence of few drivers, several signaling pathways are involved in the oncogenesis of this cancer type, some of them with promising targets for precision oncology. Pancreatic cancer is recognized as one of immunosuppressive phenotype cancer: it is characterized by a fibrotic-desmoplastic stroma, in which there is an intensive cross-talk between several cellular (e.g., fibroblasts, myeloid cells, lymphocytes, endothelial, and myeloid cells) and acellular (collagen, fibronectin, and soluble factors) components. In this review; we aim to describe the current knowledge of the genetic/biological landscape of pancreatic cancer and the composition of its tumor microenvironment; in order to better direct in the intrinsic labyrinth of this complex tumor type. Indeed; disentangling the genetic and molecular characteristics of cancer cells and the environment in which they evolve may represent the crucial step towards more effective therapeutic strategies

Translational Landscape of mTOR Signaling in Integrating Cues Between Cancer and Tumor Microenvironment

The mammalian target of rapamycin (mTOR) represents a critical hub for the regulation of different processes in both normal and tumor cells. Furthermore, it is now well established the role of mTOR in integrating and shaping different environmental paracrine and autocrine stimuli in tumor microenvironment (TME) constituents. Recently, further efforts have been employed to understand how the mTOR signal transduction mechanisms modulate the sensitivity and resistance to targeted therapies, also for its involvement of mTOR also in modulating angiogenesis and tumor immunity. Indeed, interest in mTOR targeting was increased to improve immune response against cancer and to develop new long-term efficacy strategies, as demonstrated by clinical success of mTOR and immune checkpoint inhibitor combinations. In this chapter, we will describe the role of mTOR in modulating TME elements and the implication in its targeting as a great promise in clinical trials.

Pancreatic ductal adenocarcinoma: biological hallmarks, current status, and future perspectives of combined modality treatment approaches

Pancreatic ductal adenocarcinoma (PDAC) is a highly devastating disease with poor prognosis and rising incidence. Late detection and a particularly aggressive biology are the major challenges which determine therapeutic failure. In this review, we present the current status and the recent advances in PDAC treatment together with the biological and immunological hallmarks of this cancer entity. On this basis, we discuss new concepts combining distinct treatment modalities in order to improve therapeutic efficacy and clinical outcome - with a specific focus on protocols involving radio(chemo)therapeutic approaches.

PTEN as a Prognostic/Predictive Biomarker in Cancer: An Unfulfilled Promise?

Identifying putative biomarkers of clinical outcomes in cancer is crucial for successful enrichment, and for the selection of patients who are the most likely to benefit from a specific therapeutic approach. Indeed, current research in personalized cancer therapy focuses on the possibility of identifying biomarkers that predict prognosis, sensitivity or resistance to therapies. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates several crucial cell functions such as proliferation, survival, genomic stability and cell motility through both enzymatic and non-enzymatic activities and phosphatidylinositol 3-kinase (PI3K)-dependent and -independent mechanisms. Despite its undisputed role as a tumor suppressor, assessment of PTEN status in sporadic human tumors has yet to provide clinically robust prognostic, predictive or therapeutic information. This is possibly due to the exceptionally complex regulation of PTEN function, which involves genetic, transcriptional, post-transcriptional and post-translational events. This review shows a brief summary of the regulation and function of PTEN and discusses its controversial aspects as a prognostic/predictive biomarker.

Integrative landscape of dysregulated signaling pathways of clinically distinct pancreatic cancer subtypes

Despite modern therapeutic advances, the survival prospects of pancreatic cancer patients have remained poor. Besides being highly metastatic, pancreatic cancer is challenging to treat because it is caused by a heterogeneous array of somatic mutations that impact a variety of signaling pathways and cellular regulatory systems. Here we use publicly available transcriptomic, copy number alteration and mutation profiling datasets from pancreatic cancer patients together with data on disease outcomes to show that the three major pancreatic cancer subtypes each display distinctive aberrations in cell signaling and metabolic pathways. Importantly, patients afflicted with these different pancreatic cancer subtypes also exhibit distinctive survival profiles. Within these patients, we find that dysregulation of the phosphoinositide 3-kinase and mitogen-activated protein kinase pathways, and p53 mediated disruptions of cell cycle processes are apparently drivers of disease. Further, we identify for the first time the molecular perturbations of signalling networks that are likely the primary causes of oncogenesis in each of the three pancreatic cancer subtypes.

mTOR Cross-Talk in Cancer and Potential for Combination Therapy

The mammalian Target of Rapamycin (mTOR) pathway plays an essential role in sensing and integrating a variety of exogenous cues to regulate cellular growth and metabolism, in both physiological and pathological conditions. mTOR functions through two functionally and structurally distinct multi-component complexes, mTORC1 and mTORC2, which interact with each other and with several elements of other signaling pathways. In the past few years, many new insights into mTOR function and regulation have been gained and extensive genetic and pharmacological studies in mice have enhanced our understanding of how mTOR dysfunction contributes to several diseases, including cancer. Single-agent mTOR targeting, mostly using rapalogs, has so far met limited clinical success; however, due to the extensive cross-talk between mTOR and other pathways, combined approaches are the most promising avenues to improve clinical efficacy of available therapeutics and overcome drug resistance. This review provides a brief and up-to-date narrative on the regulation of mTOR function, the relative contributions of mTORC1 and mTORC2 complexes to cancer development and progression, and prospects for mTOR inhibition as a therapeutic strategy.