Phase I study of a chloroquine-gemcitabine combination in patients with metastatic or unresectable pancreatic cancer

Hydroxychloroquine in combination with platinum doublet chemotherapy as first-line treatment for extensive-stage small cell lung cancer (Study 15): A randomised phase II multicentre trial

BACKGROUND

Most patients with small-cell lung cancer (SCLC) present with extensive-stage (ES) disease and have a poor prognosis despite achieving high initial response rates to platinum-based doublet chemotherapy. This study evaluated whether adding hydroxychloroquine (HCQ) to chemotherapy could improve outcomes.

METHODS

This was a randomised multicentre phase II trial. Eligible patients had untreated ES-SCLC, a performance status 0-2 and measurable disease. Patients were randomly assigned (1:1 ratio) to HCQ (400 mg orally twice daily) plus carboplatin-gemcitabine or carboplatin-etoposide alone. Chemotherapy was administered for up to six cycles, with HCQ given concurrently and then as single agent for up to 30 months. Primary endpoint was PFS, aiming for a hazard ratio (HR) of 0.70.

RESULTS

72 patients were randomised (36 HCQ+chemotherapy and 36 chemotherapy alone). Median HCQ treatment duration was 4.4 months. HCQ did not improve PFS (HR 1·12 95 %CI 0·69-1.84; p = 0·64), with a median of 5.7 months (HCQ+chemotherapy) versus 6.2 months (chemotherapy). The corresponding median OS were 8.9 and 10.2 months (HR 0.83, 95 %CI 0.48-1.45, p = 0.52). Fewer patients in the HCQ arm completed four cycles of chemotherapy due to adverse events (64 % vs. 81 %). Grade ≥ 3 adverse events were higher in the HCQ+chemotherapy arm (83.3 % vs. 27.8 %), primarily anaemia, neutropenia, and thrombocytopenia, partly due to the initially higher gemcitabine dose used CONCLUSIONS: Combining HCQ with platinum doublet chemotherapy did not improve PFS or OS outcomes for ES-SCLC, resulting in more patients stopping chemotherapy due to increased adverse events. When considered alongside other randomised studies of HCQ in cancer, the evidence collectively indicates a limited role for HCQ as a therapeutic option.

Risk factors of using late-autophagy inhibitors: Aspects to consider when combined with anticancer therapies

Cancer resistance to therapy is still an unsolved scientific and clinical problem. In 2022, the hallmarks of cancer have been expanded to include four new features, including cellular senescence. Therapy-induced senescence (TIS) is a stressor-based response to conventional treatment methods, e.g. chemo- and radiotherapy, but also to non-conventional targeted therapies. Since TIS reinforces resistance in cancers, new strategies for sensitizing cancer cells to therapy are being adopted. These include macroautophagy as a potential target for inhibition due to its potential cytoprotective role in many cancers. The mechanism of late-stage autophagy inhibitors is based on blockage of autophagolysosome formation or an increase in lysosomal pH, resulting in disrupted cargo degradation. Such inhibitors are relevant candidates for increasing anticancer therapy effectiveness. In particular, 4-aminoquoline derivatives: chloroquine/hydroxychloroquine (CQ/HCQ) have been tested in multiple clinical trials in combination with senescence-inducing anti-cancer drugs. In this review, we summarize the properties of selected late-autophagy inhibitors and their role in the regulation of autophagy and senescent cell phenotype in vitro and in vivo models of cancer as well as treatment response in clinical trials on oncological patients. Additionally, we point out that, although these compounds increase the effectiveness of treatment in some cases, their practical usage might be hindered due to systemic toxicity, hypoxic environment, dose- ant time-dependent inhibitory effects, as well as a possible contribution to escaping from TIS.

Current trends and future prospects of drug repositioning in gastrointestinal oncology

Gastrointestinal (GI) cancers comprise a significant number of cancer cases worldwide and contribute to a high percentage of cancer-related deaths. To improve survival rates of GI cancer patients, it is important to find and implement more effective therapeutic strategies with better prognoses and fewer side effects. The development of new drugs can be a lengthy and expensive process, often involving clinical trials that may fail in the early stages. One strategy to address these challenges is drug repurposing (DR). Drug repurposing is a developmental strategy that involves using existing drugs approved for other diseases and leveraging their safety and pharmacological data to explore their potential use in treating different diseases. In this paper, we outline the existing therapeutic strategies and challenges associated with GI cancers and explore DR as a promising alternative approach. We have presented an extensive review of different DR methodologies, research efforts and examples of repurposed drugs within various GI cancer types, such as colorectal, pancreatic and liver cancers. Our aim is to provide a comprehensive overview of employing the DR approach in GI cancers to inform future research endeavors and clinical trials in this field.

Sensitivity of osteosarcoma cell lines to autophagy inhibition as determined by pharmacologic and genetic manipulation

Pharmacologic inhibition of autophagy can be achieved using lysosomotropic agents such as hydroxychloroquine (HCQ) that interfere with fusion of the autophagosome to the lysosome thus preventing completion of the recycling process. The goal of the present study is to determine the sensitivity of eight canine (cOSA) and four human (hOSA) osteosarcoma tumour cell lines to antiproliferative and cytotoxic effects of lysosomal autophagy inhibitors, and to compare these results to the autophagy-dependence measured using a CRISPR/Cas9 live-cell imaging assay in OSA and other tumour cell lines. Antiproliferative and cytotoxic response to HCQ and Lys05 was determined using live cell imaging and YOYO-1 staining. CRISPR/Cas9 live cell imaging screen was done using species specific guide RNA's and transfection of reagents into cells. Response to autophagy core genes was compared to response to an essential (PCNA) and non-essential (FOXO3A) gene. cOSA and hOSA cell lines showed similar antiproliferative and cytotoxic responses to HCQ and Lys05 with median lethal dose (Dm ) values ranging from 4.6-15.8 μM and 2.1-5.1 μM for measures of anti-proliferative response, respectively. A relationship was observed between antiproliferative responses to HCQ and Lys05 and VPS34 CRISPR score with Dm values correlating with VPS34 response (r = 0.968 and 0.887) in a species independent manner. The results show that a subset of cOSA and hOSA cell lines are autophagy-dependent and sensitive to HCQ at pharmacologically-relevant exposures.

Genetic assessment of pathogenic germline alterations in lysosomal genes among Asian patients with pancreatic ductal adenocarcinoma

BACKGROUND

Lysosomes are closely linked to autophagic activity, which plays a vital role in pancreatic ductal adenocarcinoma (PDAC) biology. The survival of PDAC patients is still poor, and the identification of novel genetic factors for prognosis and treatment is highly required to prevent PDAC-related deaths. This study investigated the germline variants related to lysosomal dysfunction in patients with PDAC and to analyze whether they contribute to the development of PDAC.

METHODS

The germline putative pathogenic variants (PPV) in genes involved in lysosomal storage disease (LSD) was compared between patients with PDAC (n = 418) and healthy controls (n = 845) using targeted panel and whole-exome sequencing. Furthermore, pancreatic organoids from wild-type and KrasG12D mice were used to evaluate the effect of lysosomal dysfunction on PDAC development. RNA sequencing (RNA-seq) analysis was performed with established PDAC patient-derived organoids (PDOs) according to the PPV status.

RESULTS

The PPV in LSD-related genes was higher in patients with PDAC than in healthy controls (8.13 vs. 4.26%, Log2 OR = 1.65, P = 3.08 × 10-3). The PPV carriers of LSD-related genes with PDAC were significantly younger than the non-carriers (mean age 61.5 vs. 65.3 years, P = 0.031). We further studied a variant of the lysosomal enzyme, galactosylceramidase (GALC), which was the most frequently detected LSD variant in our cohort. Autophagolysosomal activity was hampered when GALC was downregulated, which was accompanied by paradoxically elevated autophagic flux. Furthermore, the number of proliferating Ki-67+ cells increased significantly in pancreatic organoids derived from Galc knockout KrasG12D mice. Moreover, GALC PPV carriers tended to show drug resistance in both PDAC cell line and PDAC PDO, and RNA-seq analysis revealed that various metabolism and gene repair pathways were upregulated in PDAC PDOs harboring a GALC variant.

CONCLUSIONS

Genetically defined lysosomal dysfunction is frequently observed in patients with young-onset PDAC. This might contribute to PDAC development by altering metabolism and impairing autophagolysosomal activity, which could be potentially implicated in therapeutic applications for PDAC.

Unravelling the complexity of lncRNAs in autophagy to improve potential cancer therapy

Autophagy is well-known as an internal catabolic process that is evolutionarily conserved and performs the key biological function in maintaining cellular homeostasis. It is tightly controlled by several autophagy-related (ATG) proteins, which are closely associated with many types of human cancers. However, what has remained controversial is the janus roles of autophagy in cancer progression. Interestingly, the biological function of long non-coding RNAs (lncRNAs) in autophagy has been gradually understood in different types of human cancers. More recently, numerous studies have demonstrated that several lncRNAs may regulate some ATG proteins and autophagy-related signaling pathways to either activate or inhibit the autophagic process in cancer. Thus, in this review, we summarize the latest advance in the knowledge of the complicated relationships between lncRNAs and autophagy in cancer. Also, the in-depth dissection of the lncRNAs-autophagy-cancers axis involved in this review would shed new light on discovery of more potential cancer biomarkers and therapeutic targets in the future.

Autophagy inhibitors for cancer therapy: Small molecules and nanomedicines

Autophagy is a conserved process in which the cytosolic materials are degraded and eventually recycled for cellular metabolism to maintain homeostasis. The dichotomous role of autophagy in pathogenesis is complicated. Accumulating reports have suggested that cytoprotective autophagy is responsible for tumor growth and progression. Autophagy inhibitors, such as chloroquine (CQ) and hydroxychloroquine (HCQ), are promising for treating malignancies or overcoming drug resistance in chemotherapy. With the rapid development of nanotechnology, nanomaterials also show autophagy-inhibitory effects or are reported as the carriers delivering autophagy inhibitors. In this review, we summarize the small-molecule compounds and nanomaterials inhibiting autophagic flux as well as the mechanisms involved. The nanocarrier-based drug delivery systems for autophagy inhibitors and their distinct advantages are also described. The progress of autophagy inhibitors for clinical applications is finally introduced, and their future perspectives are discussed.

The role of epithelial-mesenchymal transition and autophagy in pancreatic ductal adenocarcinoma invasion

Of all pancreatic cancer (PC) cases, approximately 90% are pancreatic ductal adenocarcinoma (PDAC), which progress rapidly due to its high degree of invasiveness and high metastatic potential. Epithelial-mesenchymal transition (EMT) is a prerequisite for cancer cell invasion and spread, and it is mediated by the specific cellular behaviors and the tumor microenvironment. Autophagy has long been a target of cancer therapy, and it has been considered to play a dual and contradictory role, particularly regarding EMT-mediated PDAC invasion. This review discusses the characteristics and the biological role of EMT and autophagy from a cellular perspective, explaining invasion as a survival behavior of PDAC, with the aim of providing novel insights into targeting EMT and autophagy to overcome PDAC invasion.

What Is the Significance of Lysosomal-Mediated Resistance to Imatinib?

The lysosomal sequestration of hydrophobic weak-base anticancer drugs is one proposed mechanism for the reduced availability of these drugs at target sites, resulting in a marked decrease in cytotoxicity and consequent resistance. While this subject is receiving increasing emphasis, it is so far only in laboratory experiments. Imatinib is a targeted anticancer drug used to treat chronic myeloid leukaemia (CML), gastrointestinal stromal tumours (GISTs), and a number of other malignancies. Its physicochemical properties make it a typical hydrophobic weak-base drug that accumulates in the lysosomes of tumour cells. Further laboratory studies suggest that this might significantly reduce its antitumor efficacy. However, a detailed analysis of published laboratory studies shows that lysosomal accumulation cannot be considered a clearly proven mechanism of resistance to imatinib. Second, more than 20 years of clinical experience with imatinib has revealed a number of resistance mechanisms, none of which is related to its accumulation in lysosomes. This review focuses on the analysis of salient evidence and raises a fundamental question about the significance of lysosomal sequestration of weak-base drugs in general as a possible resistance mechanism both in clinical and laboratory settings.

Clustering analysis revealed the autophagy classification and potential autophagy regulators' sensitivity of pancreatic cancer based on multi-omics data

BACKGROUND

Pancreatic ductal adenocarcinoma (PDAC) is a lethal malignancy and is unresponsive to conventional therapeutic modalities due to its high heterogeneity, expounding the necessity, and priority of searching for effective biomarkers and drugs. Autophagy, as an evolutionarily conserved biological process, is upregulated in PDAC and its regulation is linked to a poor prognosis. Increased autophagy sequestered MHC-I on PDAC cells and weaken the antigen presentation and antitumor immune response, indicating the potential therapeutic strategies of autophagy inhibitors.

METHODS

By performing 10 state-of-the-art multi-omics clustering algorithms, we constructed a robust PDAC classification model to reveal the autophagy-related genes among different subgroups.

OUTCOMES

After building a more comprehensive regulating network for potential autophagy regulators exploration, we concluded the top 20 autophagy-related hub genes (GAPDH, MAPK3, RHEB, SQSTM1, EIF2S1, RAB5A, CTSD, MAP1LC3B, RAB7A, RAB11A, FADD, CFKN2A, HSP90AB1, VEGFA, RELA, DDIT3, HSPA5, BCL2L1, BAG3, and ERBB2), six miRNAs, five transcription factors, and five immune infiltrated cells as biomarkers. The drug sensitivity database was screened based on the biomarkers to predict possible drug-targeting signal pathways, hoping to yield novel insights, and promote the progress of the anticancer therapeutic strategy.

CONCLUSION

We succefully constructed an autophagy-related mRNA/miRNA/TF/Immune cells network based on a 10 state-of art algorithm multi-omics analysis, and screened the drug sensitivity dataset for detecting potential signal pathway which might be possible autophagy modulators' targets.

Effects of chloroquine and hydroxychloroquine on the sensitivity of pancreatic cancer cells to targeted therapies

Approaches to improve pancreatic cancer therapy are essential as this disease has a very bleak outcome. Approximately 80% of pancreatic cancers are pancreatic ductal adenocarcinomas (PDAC). PDAC is a cancer which is difficult to effectively treat as it is often detected late in the disease process. Almost all PDACs (over 90%) have activating mutations in the GTPase gene KRAS. These mutations result in constitutive KRas activation and the mobilization of downstream pathways such as the Raf/MEK/ERK pathway. Small molecule inhibitors of key components of the KRas/Raf/MEK/ERK pathways as well as monoclonal antibodies (MoAbs) specific for upstream growth factor receptors such insulin like growth factor-1 receptor (IGF1-R) and epidermal growth factor receptors (EGFRs) have been developed and have been evaluated in clinical trials. An additional key regulatory gene frequently mutated (∼75%) in PDAC is the TP53 tumor suppressor gene which controls the transcription of multiple genes involved in cell cycle progression, apoptosis, metabolism, cancer progression and other growth regulatory processes. Small molecule mutant TP53 reactivators have been developed which alter the structure of mutant TP53 protein and restore some of its antiproliferative activities. Some mutant TP53 reactivators have been examined in clinical trials with patients with mutant TP53 genes. Inhibitors to the TP53 negative regulator Mouse Double Minute 2 (MDM2) have been developed and analyzed in clinical trials. Chloroquine and hydroxychloroquine are established anti-malarial and anti-inflammatory drugs that also prevent the induction of autophagy which can have effects on cancer survival. Chloroquine and hydroxychloroquine have also been examined in various clinical trials. Recent studies are suggesting effective treatment of PDAC patients may require chemotherapy as well as targeting multiple pathways and biochemical processes.

Targeting autophagy in pancreatic cancer: The cancer stem cell perspective

Pancreatic cancer is currently the seventh leading cause of cancer-related deaths worldwide, with the estimated death toll approaching half a million annually. Pancreatic ductal adenocarcinoma (PDAC) is the most common (>90% of cases) and most aggressive form of pancreatic cancer, with extremely poor prognosis and very low survival rates. PDAC is initiated by genetic alterations, usually in the oncogene KRAS and tumor suppressors CDKN2A, TP53 and SMAD4, which in turn affect a number of downstream signaling pathways that regulate important cellular processes. One of the processes critically altered is autophagy, the mechanism by which cells clear away and recycle impaired or dysfunctional organelles, protein aggregates and other unwanted components, in order to achieve homeostasis. Autophagy plays conflicting roles in PDAC and has been shown to act both as a positive effector, promoting the survival of pancreatic tumor-initiating cells, and as a negative effector, increasing cytotoxicity in uncontrollably expanding cells. Recent findings have highlighted the importance of cancer stem cells in PDAC initiation, progression and metastasis. Pancreatic cancer stem cells (PaCSCs) comprise a small subpopulation of the pancreatic tumor, characterized by cellular plasticity and the ability to self-renew, and autophagy has been recognised as a key process in PaCSC maintenance and function, simultaneously suggesting new strategies to achieve their selective elimination. In this review we evaluate recent literature that links autophagy with PaCSCs and PDAC, focusing our discussion on the therapeutic implications of pharmacologically targeting autophagy in PaCSCs, as a means to treat PDAC.

Focusing on the Role of Natural Products in Overcoming Cancer Drug Resistance: An Autophagy-Based Perspective

Autophagy is a critical cellular adaptive response in tumor formation. Nutritional deficiency and hypoxia exacerbate autophagic flux in established malignancies, promoting tumor cell proliferation, migration, metastasis, and resistance to therapeutic interventions. Pro-survival autophagy inhibition may be a promising treatment option for advanced cancer. Furthermore, excessive or persistent autophagy is cytotoxic, resulting in tumor cell death. Targeted autophagy activation has also shown significant promise in the fight against tumor drug resistance. Several research groups have examined the ability of natural products (NPs) such as alkaloids, terpenoids, polyphenols, and anthraquinones to serve as autophagy inhibitors or activators. The data support the capacity of NPs that promote lethal autophagy or inhibit pro-survival autophagy from being employed against tumor drug resistance. This paper discusses the potential applications of NPs that regulate autophagy in the fight against tumor drug resistance, some limitations of the current studies, and future research needs and priorities.

Novel 7-Chloro-(4-thioalkylquinoline) Derivatives: Synthesis and Antiproliferative Activity through Inducing Apoptosis and DNA/RNA Damage

A series of 78 synthetic 7-chloro-(4-thioalkylquinoline) derivatives were investigated for cytotoxic activity against eight human cancer as well as 4 non-tumor cell lines. The results showed, with some exceptions, that sulfanyl 5-40 and sulfinyl 41-62 derivatives exhibited lower cytotoxicity for cancer cell lines than those of well-described sulfonyl N-oxide derivatives 63-82. As for compound 81, the most pronounced selectivity (compared against BJ and MRC-5 cells) was observed for human cancer cells from HCT116 (human colorectal cancer with wild-type p53) and HCT116p53-/- (human colorectal cancer with deleted p53), as well as leukemia cell lines (CCRF-CEM, CEM-DNR, K562, and K562-TAX), lung (A549), and osteosarcoma cells (U2OS). A good selectivity was also detected for compounds 73 and 74 for leukemic and colorectal (with and without p53 deletion) cancer cells (compared to MRC-5). At higher concentrations (5 × IC₅₀) against the CCRF-CEM cancer cell line, we observe the accumulation of the cells in the G0/G1 cell phase, inhibition of DNA and RNA synthesis, and induction of apoptosis. In addition, X-ray data for compound 15 is being reported. These results provide useful scientific data for the development of 4-thioalkylquinoline derivatives as a new class of anticancer candidates.

Recent advances in glioblastoma multiforme therapy: A focus on autophagy regulation

Despite conventional treatment options including chemoradiation, patients with the most aggressive primary brain tumor, glioblastoma multiforme (GBM), experience an average survival time of less than 15 months. Regarding the malignant nature of GBM, extensive research and discovery of novel treatments are urgently required to improve the patients' prognosis. Autophagy, a crucial physiological pathway for the degradation and recycling of cell components, is one of the exciting targets of GBM studies. Interventions aimed at autophagy activation or inhibition have been explored as potential GBM therapeutics. This review, which delves into therapeutic techniques to block or activate autophagy in preclinical and clinical research, aims to expand our understanding of available therapies battling GBM.

Role of interferon-gamma (IFN-γ) and IFN-γ receptor 1/2 (IFNγR1/2) in regulation of immunity, infection, and cancer development: IFN-γ-dependent or independent pathway

IFN-γ, a soluble cytokine being produced by T lymphocytes, macrophages, mucosal epithelial cells, or natural killer cells, is able to bind to the IFN-γ receptor (IFNγR) and in turn activate the Janus kinase (JAK)-signal transducer and transcription protein (STAT) pathway and induce expression of IFN-γ-stimulated genes. IFN-γ is critical for innate and adaptive immunity and aberrant IFN-γ expression and functions have been associated with different human diseases. However, the IFN-γ/IFNγR signaling could be a double-edged sword in cancer development because the tissue microenvironments could determine its anti- or pro-tumorigenic activities. The IFNγR protein consists of two IFNγR1 and IFNγR2 chains, subunits of which play different roles under certain conditions. This review assessed IFNγR polymorphisms, expression and functions in development and progression of various human diseases in an IFN-γ-dependent or independent manner. This review also discussed tumor microenvironment, microbial infection, and vital molecules in the IFN-γ upstream signaling that might regulate IFNγR expression, drug resistance, and druggable strategy, to provide evidence for further application of IFNγR.

Targeting autophagy as a therapeutic strategy against pancreatic cancer

Macroautophagy (hereafter autophagy) is a catabolic process through which cytosolic components are captured in the autophagosome and degraded in the lysosome. Autophagy plays two major roles: nutrient recycling under starvation or stress conditions and maintenance of cellular homeostasis by removing the damaged organelles or protein aggregates. In established cancer cells, autophagy-mediated nutrient recycling promotes tumor progression, whereas in normal/premalignant cells, autophagy suppresses tumor initiation by eliminating the oncogenic/harmful molecules. Pancreatic ductal adenocarcinoma (PDAC) is a deadly disease that is refractory to most currently available treatment modalities, including immune checkpoint blockade and molecular-targeted therapy. One prominent feature of PDAC is its constitutively active and elevated autophagy-lysosome function, which enables PDAC to thrive in its nutrient-scarce tumor microenvironment. In addition to metabolic support, autophagy promotes PDAC progression in a metabolism-independent manner by conferring resistance to therapeutic treatment or facilitating immune evasion. Besides to cell-autonomous autophagy in cancer cells, host autophagy (autophagy in non-cancer cells) supports PDAC progression, further highlighting autophagy as a promising therapeutic target in PDAC. Based on a growing list of compelling preclinical evidence, there are numerous ongoing clinical trials targeting the autophagy-lysosome pathway in PDAC. Given the multifaceted and context-dependent roles of autophagy in both cancer cells and normal host cells, a deeper understanding of the mechanisms underlying the tumor-promoting roles of autophagy as well as of the consequences of autophagy inhibition is necessary for the development of autophagy inhibition-based therapies against PDAC.

Autophagy, Oxidative Stress and Cancer Development

Simple Summary

Autophagy, as an important cellular repair mechanism, is important for the prevention of several diseases, including metabolic and neurologic disorders, and cancer. Hence, dysfunctional autophagy has been linked to these diseases, and in recent years researchers have tried to outline therapeutic targets in autophagy-related pathways as a treatment. With this review of the literature, we want to give an overview about the connection between oxidative stress, autophagy and cancer.

Abstract

Autophagy is an important cellular repair mechanism, aiming at sequestering misfolded and dysfunctional proteins and damaged cell organelles. Dysfunctions in the autophagy process have been linked to several diseases, like infectious and neurodegenerative diseases, type II diabetes mellitus and cancer. Living organisms are constantly subjected to some degree of oxidative stress, mainly induced by reactive oxygen and nitrogen species. It has been shown that autophagy is readily induced by reactive oxygen species (ROS) upon nutrient deprivation. In recent years, research has increasingly focused on outlining novel therapeutic targets related to the autophagy process. With this review of the literature, we want to give an overview about the link between autophagy, oxidative stress and carcinogenesis.

Autophagy Agents in Clinical Trials for Cancer Therapy: A Brief Review

Autophagy has been of novel interest since it was first demonstrated to have effect in Burkitt's lymphoma. Since that time, the autophagy agents chloroquine and hydroxychloroquine have become the only FDA (Food and Drug Administration)-approved autophagy inhibitors. While not approved for cancer therapy, there are ongoing clinical trials to evaluate their safety and efficacy. Pevonedistat has emerged as a novel inhibitor through the neddylation pathway and is an autophagy activator. This paper summarizes and presents current clinical trials for hydroxychloroquine (HCQ), chloroquine (CQ), and Pevonedistat for the clinician.

Autophagy Contributes to Metabolic Reprogramming and Therapeutic Resistance in Pancreatic Tumors

Metabolic reprogramming is a feature of cancers for which recent research has been particularly active, providing numerous insights into the mechanisms involved. It occurs across the entire cancer process, from development to resistance to therapies. Established tumors exhibit dependencies for metabolic pathways, constituting vulnerabilities that can be targeted in the clinic. This knowledge is of particular importance for cancers that are refractory to any therapeutic approach, such as Pancreatic Ductal Adenocarcinoma (PDAC). One of the metabolic pathways dysregulated in PDAC is autophagy, a survival process that feeds the tumor with recycled intracellular components, through both cell-autonomous (in tumor cells) and nonautonomous (from the local and distant environment) mechanisms. Autophagy is elevated in established PDAC tumors, contributing to aberrant proliferation and growth even in a nutrient-poor context. Critical elements link autophagy to PDAC including genetic alterations, mitochondrial metabolism, the tumor microenvironment (TME), and the immune system. Moreover, high autophagic activity in PDAC is markedly related to resistance to current therapies. In this context, combining autophagy inhibition with standard chemotherapy, and/or drugs targeting other vulnerabilities such as metabolic pathways or the immune response, is an ongoing clinical strategy for which there is still much to do through translational and multidisciplinary research.

Therapeutic Targeting of Autophagy in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease characterized by early metastasis, late detection, and poor prognosis. Progress towards effective therapy has been slow despite significant efforts. Novel treatment approaches are desperately needed and autophagy, an evolutionary conserved process through which proteins and organelles are recycled for use as alternative energy sources, may represent one such target. Although incompletely understood, there is growing evidence suggesting that autophagy may play a role in PDAC carcinogenesis, metastasis, and survival. Early clinical trials involving autophagy inhibiting agents, either alone or in combination with chemotherapy, have been disappointing. Recently, evidence has demonstrated synergy between the MAPK pathway and autophagy inhibitors in PDAC, suggesting a promising therapeutic intervention. In addition, novel agents, such as ONC212, have preclinical activity in pancreatic cancer, in part through autophagy inhibition. We discuss autophagy in PDAC tumorigenesis, metabolism, modulation of the immune response, and preclinical and clinical data with selected autophagy modulators as therapeutics.

Chloroquine Potentiates the Anticancer Effect of Pterostilbene on Pancreatic Cancer by Inhibiting Autophagy and Downregulating the RAGE/STAT3 Pathway

The treatment of pancreatic ductal adenocarcinoma (PDAC) remains a huge challenge, because pro-survival signaling pathways—such as the receptor for advanced glycation end products (RAGE)/signal transducer and activator of transcription 3 (STAT3) pathway—are overexpressed in PDAC cells. Moreover, PDAC cells are highly resistant to chemotherapeutic agents because of autophagy induction. Therefore, autophagy and its modulated signaling pathways are attractive targets for developing novel therapeutic strategies for PDAC. Pterostilbene is a stilbenoid chemically related to resveratrol, and has potential for the treatment of cancers. Accordingly, we investigated whether the autophagy inhibitor chloroquine could potentiate the anticancer effect of pterostilbene in the PDAC cell lines MIA PaCa-2 and BxPC-3, as well as in an orthotopic animal model. The results indicated that pterostilbene combined with chloroquine significantly inhibited autophagy, decreased cell viability, and sensitized the cells to pterostilbene-induced apoptosis via downregulation of the RAGE/STAT3 and protein kinase B (AKT)/mammalian target of rapamycin (mTOR) pathways in PDAC cells. The results of the orthotopic animal model showed that pterostilbene combined with chloroquine significantly inhibited pancreatic cancer growth, delayed tumor quadrupling times, and inhibited autophagy and STAT3 in pancreatic tumors. In summary, the present study suggested the novel therapeutic strategy of pterostilbene combined with chloroquine against the growth of pancreatic ductal adenocarcinoma by inhibiting autophagy and downregulating the RAGE/STAT3 signaling pathways.

Next-generation immunotherapy for pancreatic ductal adenocarcinoma: navigating pathways of immune resistance

To date, the use of immune checkpoint inhibitors has proven largely ineffective in patients with advanced pancreatic ductal adenocarcinoma. A combination of low tumor antigenicity, deficits in immune activation along with an exclusive and suppressive tumor microenvironment result in resistance to host defensives. However, a deepening understanding of these immune escape and suppressive mechanisms has led to the discovery of novel molecular targets and treatment strategies that may hold the key to a long-awaited therapeutic breakthrough. In this review, we describe the tumor-intrinsic and microenvironmental barriers to modern immunotherapy, examine novel immune-based and targeted modalities, summarize relevant pre-clinical findings and human experience, and, finally, discuss novel synergistic approaches to overcome immune-resistance in pancreatic cancer. Beyond checkpoint inhibition, immune agonists and anti-tumor vaccines represent promising strategies to stimulate host response via activation and expansion of anti-tumor immune effectors. Off-the-shelf natural killer cell therapies may offer an effective method for bypassing downregulated tumor antigen presentation. In parallel with this, sophisticated targeting of crosstalk between tumor and tumor-associated immune cells may lead to enhanced immune infiltration and survival of anti-tumor lymphocytes. A future multimodal treatment strategy involving immune priming/activation, tumor microenvironment reprogramming, and immune checkpoint blockade may help transform pancreatic cancer into an immunogenic tumor.

Targeting KRAS in pancreatic cancer: new drugs on the horizon

Kirsten Rat Sarcoma (KRAS) is a master oncogene involved in cellular proliferation and survival and is the most commonly mutated oncogene in all cancers. Activating KRAS mutations are present in over 90% of pancreatic ductal adenocarcinoma (PDAC) cases and are implicated in tumor initiation and progression. Although KRAS is a critical oncogene, and therefore an important therapeutic target, its therapeutic inhibition has been very challenging, and only recently specific mutant KRAS inhibitors have been discovered. In this review, we discuss the activation of KRAS signaling and the role of mutant KRAS in PDAC development. KRAS has long been considered undruggable, and many drug discovery efforts which focused on indirect targeting have been unsuccessful. We discuss the various efforts for therapeutic targeting of KRAS. Further, we explore the reasons behind these obstacles, novel successful approaches to target mutant KRAS including G12C mutation as well as the mechanisms of resistance.

Adjuvant Treatment in Pancreatic Cancer: Shaping the Future of the Curative Setting

Pancreatic ductal adenocarcinoma (PDAC) is a lethal disease even in the early stages, despite progresses in surgical and pharmacological treatment in recent years. High potential for metastases is the main cause of therapeutic failure in localized disease, highlighting the current limited knowledge of underlying pathological processes. However, nowadays research is focusing on the search for personalized approaches also in the adjuvant setting for PDAC, by implementing the use of biomarkers and investigating new therapeutic targets. In this context, the aim of this narrative review is to summarize the current treatment scenario and new potential therapeutic approaches in early stage PDAC, from both a preclinical and clinical point of view. Additionally, the review examines the role of target therapies in localized PDAC and the influence of neoadjuvant treatments on survival outcomes.

Drug Repurposing, an Attractive Strategy in Pancreatic Cancer Treatment: Preclinical and Clinical Updates

Pancreatic cancer (PC) is one of the deadliest malignancies worldwide, since patients rarely display symptoms until an advanced and unresectable stage of the disease. Current chemotherapy options are unsatisfactory and there is an urgent need for more effective and less toxic drugs to improve the dismal PC therapy. Repurposing of non-oncology drugs in PC treatment represents a very promising therapeutic option and different compounds are currently being considered as candidates for repurposing in the treatment of this tumor. In this review, we provide an update on some of the most promising FDA-approved, non-oncology, repurposed drug candidates that show prominent clinical and preclinical data in pancreatic cancer. We also focus on proposed mechanisms of action and known molecular targets that they modulate in PC. Furthermore, we provide an explorative bioinformatic analysis, which suggests that some of the PC repurposed drug candidates have additional, unexplored, oncology-relevant targets. Finally, we discuss recent developments regarding the immunomodulatory role displayed by some of these drugs, which may expand their potential application in synergy with approved anticancer immunomodulatory agents that are mostly ineffective as single agents in PC.

The role of autophagy in pancreatic cancer progression

Patients with pancreatic cancer have an abysmal survival rate. The poor prognosis of pancreatic cancer is due to the difficulty of making an early diagnosis, high rate of metastasis, and frequent chemoresistance. In recent years, as a self-regulatory procedure within cells, the effect and mechanism of autophagy have been explored. Dysregulated autophagy serves as a double-edged sword in cancer development in which autophagy inhibits cancer initiation but promotes cancer progression. After tumor formation, activation of autophagy can induce epithelial-mesenchymal transition, regulate metabolism, specifically glutamine usage and the glycolytic process, and mediate drug resistance in pancreatic cancer. Multiple genes, RNA molecules, proteins, and certain drugs exert antitumor effects by inhibiting autophagy-mediated drug resistance. Several clinical trials have combined autophagy inhibitors with chemotherapeutic drugs in pancreatic cancer treatment, some of which have shown promising results. In conclusion, autophagy plays a vital role in pancreatic cancer progression and deserves further study.

Chloroquine and hydroxychloroquine in antitumor therapies based on autophagy-related mechanisms

Chloroquine (CQ) and hydroxychloroquine (HCQ) are the most common drugs used to relieve acute and chronic inflammatory diseases. In this article, we present a review about the use of CQ and HCQ in antitumor therapies based on autophagy mechanisms. These molecules break/discontinue autophagosome-lysosome fusions in initial phases and enhance antiproliferative action of chemotherapeutics. Their sensitizing effects of chemotherapy when used as an adjuvant option in clinical trials against cancer. However, human related-MDR genes are also under risk to develop chemo or radioresistance because cancer cells have ability to throw 4-aminoquinolines out from digestive vacuoles well. Additionally, they also have antitumor mechanism unrelated to autophagy, including cell death from apoptosis and necroptosis and immunomodulatory/anti-inflammatory properties. However, the link between some anticancer mechanisms, clinical efficacy and pharmacological safety has not yet been fully defined.

Drug Repurposing Opportunities in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is considered one of the deadliest tumors worldwide. The diagnosis is often possible only in the latter stages of the disease, with patients already presenting an advanced or metastatic tumor. It is also one of the cancers with poorest prognosis, presenting a five-year survival rate of around 5%. Treatment of PDAC is still a major challenge, with cytotoxic chemotherapy remaining the basis of systemic therapy. However, no major advances have been made recently, and therapeutic options are limited and highly toxic. Thus, novel therapeutic options are urgently needed. Drug repurposing is a strategy for the development of novel treatments using approved or investigational drugs outside the scope of the original clinical indication. Since repurposed drugs have already completed several stages of the drug development process, a broad range of data is already available. Thus, when compared with de novo drug development, drug repurposing is time-efficient, inexpensive and has less risk of failure in future clinical trials. Several repurposing candidates have been investigated in the past years for the treatment of PDAC, as single agents or in combination with conventional chemotherapy. This review gives an overview of the main drugs that have been investigated as repurposing candidates, for the potential treatment of PDAC, in preclinical studies and clinical trials.

Autophagy as a therapeutic target in pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is characterised by early metastasis and resistance to anti-cancer therapy, leading to an overall poor prognosis. Despite continued research efforts, no targeted therapy has yet shown meaningful efficacy in PDAC; mutations in the oncogene KRAS and the tumour suppressor TP53, which are the most common genomic alterations in PDAC, have so far shown poor clinical actionability. Autophagy, a conserved process allowing cells to recycle altered or unused organelles and cellular components, has been shown to be upregulated in PDAC and is implicated in resistance to both cytotoxic chemotherapy and targeted therapy. Autophagy is thus regarded as a potential therapeutic target in PDAC and other cancers. Although the molecular mechanisms of autophagy activation in PDAC are only beginning to emerge, several groups have reported interesting results when combining inhibitors of the extracellular-signal-regulated kinase/mitogen-activated protein kinase pathway and inhibitors of autophagy in models of PDAC and other KRAS-driven cancers. In this article, we review the existing preclinical data regarding the role of autophagy in PDAC, as well as results of relevant clinical trials with agents that modulate autophagy in this cancer.

AZD9291 Resistance Reversal Activity of a pH-Sensitive Nanocarrier Dual-Loaded with Chloroquine and FGFR1 Inhibitor in NSCLC

AZD9291 can effectively prolong survival of non-small cell lung cancer (NSCLC) patients. Unfortunately, the mechanism of its acquired drug resistance is largely unknown. This study shows that autophagy and fibroblast growth factor receptor 1 signaling pathways are both activated in AZD9291 resistant NSCLC, and inhibition of them, respectively, by chloroquine (CQ) and PD173074 can synergistically reverse AZD9291 resistance. Herein, a coloaded CQ and PD173074 pH-sensitive shell-core nanoparticles CP@NP-cRGD is developed to reverse AZD9291 resistance in NSCLC. CP@NP-cRGD has a high encapsulation rate and stability, and can effectively prevent the degradation of drugs in circulation process. CP@NP-cRGD can target tumor cells by enhanced permeability and retention effect and the cRGD peptide. The pH-sensitive CaP shell can realize lysosome escape and then release drugs successively. The combination of CP@NP-cRGD and AZD9291 significantly induces a higher rate of apoptosis, more G0/G1 phase arrest, and reduces proliferation of resistant cell lines by downregulation of p-ERK1/2 in vitro. CQ in CP@NP-cRGD can block protective autophagy induced by both AZD9291 and PD173074. CP@NP-cRGD combined with AZD9291 shows adequate tumor enrichment, low toxicity, and excellent antitumor effect in nude mice. It provides a novel multifunctional nanoparticle to overcome AZD9291 resistance for potential clinical applications.

Targets (Metabolic Mediators) of Therapeutic Importance in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC), an extremely aggressive invasive cancer, is the fourth most common cause of cancer-related death in the United States. The higher mortality in PDAC is often attributed to the inability to detect it until it has reached advanced stages. The major challenge in tackling PDAC is due to its elusive pathology, minimal effectiveness, and resistance to existing therapeutics. The aggressiveness of PDAC is due to the capacity of tumor cells to alter their metabolism, utilize the diverse available fuel sources to adapt and grow in a hypoxic and harsh environment. Therapeutic resistance is due to the presence of thick stroma with poor angiogenesis, thus making drug delivery to tumor cells difficult. Investigating the metabolic mediators and enzymes involved in metabolic reprogramming may lead to the identification of novel therapeutic targets. The metabolic mediators of glucose, glutamine, lipids, nucleotides, amino acids and mitochondrial metabolism have emerged as novel therapeutic targets. Additionally, the role of autophagy, macropinocytosis, lysosomal transport, recycling, amino acid transport, lipid transport, and the role of reactive oxygen species has also been discussed. The role of various pro-inflammatory cytokines and immune cells in the pathogenesis of PDAC and the metabolites involved in the signaling pathways as therapeutic targets have been previously discussed. This review focuses on the therapeutic potential of metabolic mediators in PDAC along with stemness due to metabolic alterations and their therapeutic importance.

Inhibiting autophagy to prevent drug resistance and improve anti-tumor therapy

Cytotoxic drugs remain the first-line option for cancer therapy but the development of drug-resistance by tumor cells represents a primary obstacle for successful chemotherapy. Autophagy is a physiological mechanism of cell survival efficiently used by tumor cells to avoid cell death and to induce drug-resistance. It is a macromolecular process, in which cells degrade and recycle intracellular substrates and damaged organelles to alleviate cell stress caused by nutritional deprivation, hypoxia, irradiation, and cytotoxic agents, as well. There is evidence that autophagy prevents cancer during the early steps of carcinogenesis, but once transformed, these cells show enhanced autophagy capacity and use it to survive, grow, and facilitate metastasis. Current basic studies and clinical trials show the feasibility of using pharmacological or molecular blockage of autophagy to improve the anticancer therapy efficiency. In this review, we overviewed the pathways and molecular aspects of autophagy, its role in carcinogenesis, and the evidence for its role in cancer adaptation and drug-resistance. Finally, we reviewed the clinical findings on how the autophagy interference helps to improve conventional anticancer therapy.

Dietary Energy Modulation and Autophagy: Exploiting Metabolic Vulnerabilities to Starve Cancer

Cancer cells experience unique and dynamic shifts in their metabolic function in order to survive, proliferate, and evade growth inhibition in the resource-scarce tumor microenvironment. Therefore, identification of pharmacological agents with potential to reprogram cancer cell metabolism may improve clinical outcomes in cancer therapy. Cancer cells also often exhibit an increased dependence on the process known as autophagy, both for baseline survival and as a response to stressors such as chemotherapy or a decline in nutrient availability. There is evidence to suggest that this increased dependence on autophagy in cancer cells may be exploitable clinically by combining autophagy modulators with existing chemotherapies. In light of the increased metabolic rate in cancer cells, interest is growing in approaches aimed at "starving" cancer through dietary and pharmacologic interventions that reduce availability of nutrients and pro-growth hormonal signals known to promote cancer progression. Several dietary approaches, including chronic calorie restriction and multiple forms of fasting, have been investigated for their potential anti-cancer benefits, yielding promising results in animal models. Induction of autophagy in response to dietary energy restriction may underlie some of the observed benefit. However, while interventions based on dietary energy restriction have demonstrated safety in clinical trials, uncertainty remains regarding translation to humans as well as feasibility of achieving compliance due to the potential discomfort and weight loss that accompanies dietary restriction. Further induction of autophagy through dietary or pharmacologic metabolic reprogramming interventions may enhance the efficacy of autophagy inhibition in the context of adjuvant or neo-adjuvant chemotherapy. Nonetheless, it remains unclear whether therapeutic agents aimed at autophagy induction, autophagy inhibition, or both are a viable therapeutic strategy for improving cancer outcomes. This review discusses the literature available for the therapeutic potential of these approaches.

Autophagy Takes Center Stage as a Possible Cancer Hallmark

Cancer remains one of the leading causes of death worldwide, despite significant advances in cancer research and improvements in anticancer therapies. One of the major obstacles to curing cancer is the difficulty of achieving the complete annihilation of resistant cancer cells. The resistance of cancer cells may not only be due to intrinsic factors or factors acquired during the evolution of the tumor but may also be caused by chemotherapeutic treatment failure. Conversely, autophagy is a conserved cellular process in which intracellular components, such as damaged organelles, aggregated or misfolded proteins and macromolecules, are degraded or recycled to maintain cellular homeostasis. Importantly, autophagy is an essential mechanism that plays a key role in tumor initiation and progression. Depending on the cellular context and microenvironmental conditions, autophagy acts as a double-edged sword, playing a role in inducing apoptosis or promoting cell survival. In this review, we propose several scenarios in which autophagy could contribute to cell survival or cell death. Moreover, a special focus on novel promising targets and therapeutic strategies based on autophagic resistant cells is presented.

Chloroquine combined with concurrent radiotherapy and temozolomide for newly diagnosed glioblastoma: a phase IB trial

Treatment of glioblastoma xenografts with chloroquine results in macroautophagy/autophagy inhibition, resulting in a reduction of tumor hypoxia and sensitization to radiation. Preclinical data show that EGFRvIII-expressing glioblastoma may benefit most from chloroquine because of autophagy dependency. This study is the first to explore the safety, pharmacokinetics and maximum tolerated dose of chloroquine in combination with radiotherapy and concurrent daily temozolomide in patients with a newly diagnosed glioblastoma. This study is a single-center, open-label, dose-finding phase I trial. Patients received oral chloroquine daily starting one week before the course of chemoradiation (temozolomide 75 mg/m²/d) until the end of radiotherapy (59.4 Gy/33 fractions). Thirteen patients were included in the study (n = 6: 200 mg, n = 3: 300 mg, n = 4: 400 mg chloroquine). A total of 44 adverse events, possibly related to chloroquine, were registered including electrocardiogram QTc prolongation, irreversible blurred vision and nausea/vomiting resulting in cessation of temozolomide or delay of adjuvant cycles. The maximum tolerated dose was 200 mg chloroquine. Median overall survival was 16 months (range 2–32). Median survival was 11.5 months for EGFRvIII- patients and 20 months for EGFRvIII+ patients. A daily dose of 200 mg chloroquine was determined to be the maximum tolerated dose when combined with radiotherapy and concurrent temozolomide for newly diagnosed glioblastoma. Favorable toxicity and promising overall survival support further clinical studies.

Abbreviations: AE: adverse events; CQ: chloroquine; DLT: dose-limiting toxicities; EGFR: epidermal growth factor receptor; GBM: glioblastoma; HCQ: hydroxychloroquine; IDH1/2: isocitrate dehydrogenase (NADP(+)) 1/2; MTD: maximum tolerated dose; CTC: National Cancer Institute Common Toxicity Criteria; MGMT: O-6-methylguanine-DNA methyltransferase; OS: overall survival; po qd: per os quaque die; SAE: serious adverse events; TMZ: temozolomide; WHO: World Health Organization

Pharmacological Advances of Chloroquine and Hydroxychloroquine: From Antimalarials to Investigative Therapies in COVID-19

During the coronavirus disease 2019 (COVID-19) pandemic, numerous existing chemicals have been screened for antiviral potential against the emerging coronavirus severe acute respiratory syndrome coronavirus 2. Chloroquine and hydroxychloroquine, after exhibiting potent in vitro efficacy, have gained tremendous attention. Both therapeutics are derivatives of natural alkaloid quinine and were first synthesized to treat malaria. Thereafter, the pharmaceutical applications of the agents have expanded to many new areas. In this article, the medicinal history and pharmacological activities of chloroquine and hydroxychloroquine are summarized. Antimalarial, anti-inflammatory, antitumor, antiviral properties, and therapeutic potential in the emerging viral infection COVID-19 are discussed. Pharmacokinetics, adverse effects, and toxicities are reviewed.

The rRNA synthesis inhibitor CX-5461 may induce autophagy that inhibits anticancer drug-induced cell damage to leukemia cells

Autophagy induced in cancer cells during chemotherapy is classified into two types, which differ depending on the kind of cells or anticancer drugs. The first type of autophagy contributes to the death of cells treated with drugs. In contrast, the second type plays a crucial role in preventing anticancer drug-induced cell damages; the use of an autophagy inhibitor is considered effective in improving the efficacy of chemotherapy. Thus, it is important to determine which type of autophagy is induced during chemotherapy. Here, we showed that a novel inhibitor of RNA polymerase I, suppresses growth, induces cell cycle arrest and promotes apoptosis in leukemia cell lines. The number of apoptotic cells induced by co-treatment with CX-5461 and chloroquine, an autophagy inhibitor, increased compared with CX-5461 alone. Thus, the autophagy which may be induced by CX-5461 was the second type.

Chloroquine Triggers Cell Death and Inhibits PARPs in Cell Models of Aggressive Hepatoblastoma

Background: Hepatoblastoma (HB) is the most common pediatric liver malignancy. Despite advances in chemotherapeutic regimens and surgical techniques, the survival of patients with advanced HB remains poor, underscoring the need for new therapeutic approaches. Chloroquine (CQ), a drug used to treat malaria and rheumatologic diseases, has been shown to inhibit the growth and survival of various cancer types. We examined the antineoplastic activity of CQ in cell models of aggressive HB. Methods: Seven human HB cell models, all derived from chemoresistant tumors, were cultured as spheroids in the presence of relevant concentrations of CQ. Morphology, viability, and induction of apoptosis were assessed after 48 and 96 h of CQ treatment. Metabolomic analysis and RT-qPCR based Death Pathway Finder array were used to elucidate the molecular mechanisms underlying the CQ effect in a 2-dimensional cell culture format. Quantitative western blotting was performed to validate findings at the protein level. Results: CQ had a significant dose and time dependent effect on HB cell viability both in spheroids and in 2-dimensional cell cultures. Following CQ treatment HB spheroids exhibited increased caspase 3/7 activity indicating the induction of apoptotic cell death. Metabolomic profiling demonstrated significant decreases in the concentrations of NAD⁺ and aspartate in CQ treated cells. In further investigations, oxidation of NAD⁺ decreased as consequence of CQ treatment and NAD⁺/NADH balance shifted toward NADH. Aspartate supplementation rescued cells from CQ induced cell death. Additionally, downregulated expression of PARP1 and PARP2 was observed. Conclusions: CQ treatment inhibits cell survival in cell models of aggressive HB, presumably by perturbing NAD⁺ levels, impairing aspartate bioavailability, and inhibiting PARP expression. CQ thus holds potential as a new agent in the management of HB.

Drug Sequestration in Lysosomes as One of the Mechanisms of Chemoresistance of Cancer Cells and the Possibilities of Its Inhibition

Resistance to chemotherapeutics and targeted drugs is one of the main problems in successful cancer therapy. Various mechanisms have been identified to contribute to drug resistance. One of those mechanisms is lysosome-mediated drug resistance. Lysosomes have been shown to trap certain hydrophobic weak base chemotherapeutics, as well as some tyrosine kinase inhibitors, thereby being sequestered away from their intracellular target site. Lysosomal sequestration is in most cases followed by the release of their content from the cell by exocytosis. Lysosomal accumulation of anticancer drugs is caused mainly by ion-trapping, but active transport of certain drugs into lysosomes was also described. Lysosomal low pH, which is necessary for ion-trapping is achieved by the activity of the V-ATPase. This sequestration can be successfully inhibited by lysosomotropic agents and V-ATPase inhibitors in experimental conditions. Clinical trials have been performed only with lysosomotropic drug chloroquine and their results were less successful. The aim of this review is to give an overview of lysosomal sequestration and expression of acidifying enzymes as yet not well known mechanism of cancer cell chemoresistance and about possibilities how to overcome this form of resistance.

Hydroxychloroquine and short-course radiotherapy in elderly patients with newly diagnosed high-grade glioma: a randomized phase II trial

Background

Effective treatment for patients at least 70 years with newly diagnosed glioblastoma remains challenging and alternatives to conventional cytotoxics are appealing. Autophagy inhibition has shown promising efficacy and safety in small studies of glioblastoma and other cancers.

Methods

We conducted a randomized phase II trial to compare radiotherapy with or without hydroxychloroquine (2:1 allocation). Patients aged at least 70 years with newly diagnosed high-grade glioma deemed suitable for short-course radiotherapy with an ECOG performance status of 0-1 were included. Radiotherapy treatment consisted of 30 Gy, delivered as 6 fractions given over 2 weeks (5 Gy per fraction). Hydroxychloroquine was given as 200 mg orally b.d. from 7 days prior to radiotherapy until disease progression. The primary endpoint was 1-year overall survival (OS). Secondary endpoints included progression-free survival (PFS), quality of life, and toxicity.

Results

Fifty-four patients with a median age of 75 were randomized between May 2013 and October 2016. The trial was stopped early in 2016. One-year OS was 20.3% (95% confidence interval [CI] 8.2-36.0) hydroxychloroquine group, and 41.2% (95% CI 18.6-62.6) radiotherapy alone, with a median survival of 7.9 and 11.5 months, respectively. The corresponding 6-month PFS was 35.3% (95% CI 19.3-51.7) and 29.4% (95% CI 10.7-51.1). The outcome in the control arm was better than expected and the excess of deaths in the hydroxychloroquine group appeared unrelated to cancer. There were more grade 3-5 events in the hydroxychloroquine group (60.0%) versus radiotherapy alone (38.9%) without any clear common causation.

Conclusions

Hydroxychloroquine with short-course radiotherapy did not improve survival compared to radiotherapy alone in elderly patients with glioblastoma.

Metabolism of pancreatic cancer: paving the way to better anticancer strategies

Pancreatic cancer is currently one of the most lethal diseases. In recent years, increasing evidence has shown that reprogrammed metabolism may play a critical role in the carcinogenesis, progression, treatment and prognosis of pancreatic cancer. Affected by internal or external factors, pancreatic cancer cells adopt extensively distinct metabolic processes to meet their demand for growth. Rewired glucose, amino acid and lipid metabolism and metabolic crosstalk within the tumor microenvironment contribute to unlimited pancreatic tumor progression. In addition, the metabolic reprogramming involved in pancreatic cancer resistance is also closely related to chemotherapy, radiotherapy and immunotherapy, and results in a poor prognosis. Reflective of the key role of metabolism, the number of preclinical and clinical trials about metabolism-targeted therapies for pancreatic cancer is increasing. The poor prognosis of pancreatic cancer patients might be largely improved after employing therapies that regulate metabolism. Thus, investigations of metabolism not only benefit the understanding of carcinogenesis and cancer progression but also provide new insights for treatments against pancreatic cancer.

Dissecting pharmacological effects of chloroquine in cancer treatment: interference with inflammatory signaling pathways

Chloroquines are 4-aminoquinoline-based drugs mainly used to treat malaria. At pharmacological concentrations, they have significant effects on tissue homeostasis, targeting diverse signaling pathways in mammalian cells. A key target pathway is autophagy, which regulates macromolecule turnover in the cell. In addition to affecting cellular metabolism and bioenergetic flow equilibrium, autophagy plays a pivotal role at the interface between inflammation and cancer progression. Chloroquines consequently have critical effects in tissue metabolic activity and importantly, in key functions of the immune system. In this article, we will review the work addressing the role of chloroquines in the homeostasis of mammalian tissue, and the potential strengths and weaknesses concerning their use in cancer therapy.

Effects of neoadjuvant FOLFIRINOX and gemcitabine-based chemotherapy on cancer cell survival and death in patients with pancreatic ductal adenocarcinoma

Background: The progression and response to systemic treatment of cancer is substantially dependent on the balance between cancer cell death (apoptosis and necroptosis) and cancer cell survival (autophagy). Although well characterized in experimental systems, the status of cancer cell survival and cell death in human pancreatic ductal adenocarcinoma (PDAC), especially in response to chemotherapy and different types of chemotherapy is poorly described.

Results: The median (95% confidence interval) survival was 31.6 (24.5–44.5) months after FOLFIRINOX versus 15.8 (2.0–20.5) months after gemcitabine-based therapy (p = 0.039). PDAC tissue autophagy was reduced compared to normal pancreata based on reduced BECLIN-1 expression and LC3-Lamp-2 colocalization, whilst necroptosis (RIP-1) was increased. Neoadjuvant therapy was associated with further reduced autophagy based on p62/SQSTM-1 accumulation, and increased necroptosis (RIP3 and pMLKL) and apoptosis (BAX, cleaved CASPASE-9 and CASPASE-3) markers, increased nuclear p65 (NF-κB) and extracellular HMGB1 expression, with greater CD8⁺ lymphocyte infiltration. Survival was associated with reduced autophagy and increased apoptosis. Necroptosis (RIP-3, pMLKL) and apoptosis (BAX and cleaved CASPASE-9) markers were higher after FOLFIRINOX than gemcitabine-based treatment.

Patients and methods: Cancer cell autophagy, apoptosis, and necroptosis marker expression was compared in pancreatic tissue samples from 51 subjects, comprising four groups: (1) surgical resection for PDAC after FOLFIRINOX (n = 11), or (2) after gemcitabine-based (n = 14) neoadjuvant therapy, (3) patients undergoing PDAC resection without prior chemotherapy (n = 13), and (4) normal pancreata from 13 organ donors. Marker expression was undertaken using semi-automated immunofluorescence-FACS-like analysis, defining PDAC cells by CK-7⁺ expression.

LW6 enhances chemosensitivity to gemcitabine and inhibits autophagic flux in pancreatic cancer

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LW6 inhibits proliferation and induces cell death in pancreatic cancer cells.

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LW6 improves the anti-proliferation efficacy of gemcitabine.

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LW6 enhances gemcitabine-induced cell death.

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LW6 in combination with gemcitabine decreases tumor weight.

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LW6 inhibits autophagic flux.

The efficacy of gemcitabine therapy is often insufficient for the treatment of pancreatic cancer. The current study demonstrated that LW6, a chemical inhibitor of hypoxia-inducible factor 1α, is a promising drug for enhancing the chemosensitivity to gemcitabine. LW6 monotherapy and the combination therapy of LW6 plus gemcitabine significantly inhibited cell proliferation and enhanced cell death in pancreatic cancer cells. This combination therapy also significantly reduced the tumor weight in a syngeneic orthotopic pancreatic carcinoma model without causing toxic side effects. In addition, this study provides insight into the mechanism of how LW6 interferes with the pathophysiology of pancreatic cancer. The results revealed that LW6 inhibited autophagic flux, which is defined by the accumulation of microtubule-associated protein 1 light chain 3 (LC3) and p62/SQSTM1. Moreover, these results were verified by the analysis of a tandem RFP-GFP-tagged LC3 protein. Thence, for the first time, these data demonstrate that LW6 enhances the anti-tumor effects of gemcitabine and inhibits autophagic flux. This suggests that the combination therapy of LW6 plus gemcitabine may be a novel therapeutic strategy for pancreatic cancer patients.

Corrigendum: Metabolic Dependencies in Pancreatic Cancer

[This corrects the article DOI: 10.3389/fonc.2018.00617.].

Metabolic Dependencies in Pancreatic Cancer

Pancreatic ductal adenocarcinoma (PDA) is a highly lethal cancer with a long-term survival rate under 10%. Available cytotoxic chemotherapies have significant side effects, and only marginal therapeutic efficacy. FDA approved drugs currently used against PDA target DNA metabolism and DNA integrity. However, alternative metabolic targets beyond DNA may prove to be much more effective. PDA cells are forced to live within a particularly severe microenvironment characterized by relative hypovascularity, hypoxia, and nutrient deprivation. Thus, PDA cells must possess biochemical flexibility in order to adapt to austere conditions. A better understanding of the metabolic dependencies required by PDA to survive and thrive within a harsh metabolic milieu could reveal specific metabolic vulnerabilities. These molecular requirements can then be targeted therapeutically, and would likely be associated with a clinically significant therapeutic window since the normal tissue is so well-perfused with an abundant nutrient supply. Recent work has uncovered a number of promising therapeutic targets in the metabolic domain, and clinicians are already translating some of these discoveries to the clinic. In this review, we highlight mitochondria metabolism, non-canonical nutrient acquisition pathways (macropinocytosis and use of pancreatic stellate cell-derived alanine), and redox homeostasis as compelling therapeutic opportunities in the metabolic domain.

Chloroquine plays a cell-dependent role in the response to treatment of pancreatic adenocarcinoma

In this study, our aim is to assess the role played by autophagy and its inhibition in the different PDAC cellular compartments, and its involvement in chemo-resistance using primary human pancreatic cancer-derived cells (PCC) and Cancer Associated Fibroblasts (CAF). Autophagy flux, as measured by LC3-I and -II in the presence of Chloroquine, showed a variable level in PCC and CAFs. We found no correlation between autophagy level and degree of tumor differentiation. Association of Chloroquine with gemcitabine, 5FU, oxaliplatin, irinotecan and docetaxel revealed that its effect on survival is cell- and drug-dependent in vitro and in vivo. In addition, we demonstrated that autophagy in CAFs can play an important role in sensitizing PDAC to anticancer treatments since its inhibition increased the resistance of PCCs to gemcitabine. In conclusion, this work clearly shows a heterogeneity in the effect of Chloroquine and highlights a role of CAFs autophagy in sensitizing tumors to treatments. It also reveals that the role of autophagy is more complex than expected in PDAC as well as its sensitivity to treatments.

How Tumor Cells Choose Between Epithelial-Mesenchymal Transition and Autophagy to Resist Stress-Therapeutic Implications

Tumor cells undergo epithelial-mesenchymal transition (EMT) or macroautophagy (hereafter autophagy) in response to stressors from the microenvironment. EMT ensues when stressors act on tumor cells in the presence of nutrient sufficiency, and mechanistic target of rapamycin (mTOR) appears to be the crucial signaling node for EMT induction. Autophagy, on the other hand, is induced in the presence of nutrient deprivation and/or stressors from the microenvironment with 5' adenosine monophosphate-activated protein kinase (AMPK) playing an important, but not exclusive role, in autophagy induction. Importantly, mTOR and EMT on one hand, and AMPK and autophagy on the other hand, negatively regulate each other. Such regulation occurs at different levels and suggests that, in many instances, these two stress responses are mutually exclusive. Nevertheless, EMT and autophagy are able to interconvert and we suggest that this may depend on spatiotemporal changes in the tumor microenvironment and/or on duration/intensity of the stressor signal(s). Eventually, we propose a three-pronged therapeutic approach aimed at targeting these three major tumor cell populations. First, cytotoxic drugs that act on differentiated and proliferating tumor cells and which, per se, may promote induction of EMT or autophagy in surviving tumor cells. Second, inhibitors of mTOR in order to prevent EMT induction. Third inducers of autophagic cell death (autosis) in order to deplete tumor cells that are constitutively in an autophagic state or are induced to enter an autophagic state in response to antitumor therapy.