Sorafenib has potent antitumor activity against multiple myeloma in vitro, ex vivo, and in vivo in the 5T33MM mouse model

Anti-Angiogenic Activity of Drugs in Multiple Myeloma

Angiogenesis represents a pivotal hallmark of multiple myeloma (MM) that correlates to patients’ prognosis, overall survival, and drug resistance. Hence, several anti-angiogenic drugs that directly target angiogenic cytokines (i.e., monoclonal antibodies, recombinant molecules) or their cognate receptors (i.e., tyrosine kinase inhibitors) have been developed. Additionally, many standard antimyeloma drugs currently used in clinical practice (i.e., immunomodulatory drugs, bisphosphonates, proteasome inhibitors, alkylating agents, glucocorticoids) show anti-angiogenic effects further supporting the importance of inhibiting angiogenesis from potentiating the antimyeloma activity. Here, we review the most important anti-angiogenic therapies used for the management of MM patients with a particular focus on their pharmacological profile and on their anti-angiogenic effect in vitro and in vivo. Despite the promising perspective, the direct targeting of angiogenic cytokines/receptors did not show a great efficacy in MM patients, suggesting the need to a deeper knowledge of the BM angiogenic niche for the design of novel multi-targeting anti-angiogenic therapies.

Autophagy and Apoptosis: Current Challenges of Treatment and Drug Resistance in Multiple Myeloma

Over the past two decades, the natural history of multiple myeloma (MM) has evolved dramatically, owing primarily to novel agents targeting MM in the bone marrow microenvironment (BMM) pathways. However, the mechanisms of resistance acquisition remain a mystery and are poorly understood. Autophagy and apoptosis are tightly controlled processes and play a critical role in the cell growth, development, and survival of MM. Genetic instability and abnormalities are two hallmarks of MM. During MM progression, plasma malignant cells become genetically unstable and activate various signaling pathways, resulting in the overexpression of abnormal proteins that disrupt autophagy and apoptosis biological processes. Thus, achieving a better understanding of the autophagy and apoptosis processes and the proteins that crosslinked both pathways, could provide new insights for the MM treatment and improve the development of novel therapeutic strategies to overcome resistance. This review presents a sufficient overview of the roles of autophagy and apoptosis and how they crosslink and control MM progression and drug resistance. Potential combination targeting of both pathways for improving outcomes in MM patients also has been addressed.

Pathogenesis and treatment of multiple myeloma

Multiple myeloma (MM) is the second‐ranking malignancy in hematological tumors. The pathogenesis of MM is complex with high heterogeneity, and the development of the disease is a multistep process. Chromosomal translocations, aneuploidy, genetic mutations, and epigenetic aberrations are essential in disease initiation and progression. The correlation between MM cells and the bone marrow microenvironment is associated with the survival, progression, migration, and drug resistance of MM cells. In recent decades, there has been a significant change in the paradigm for the management of MM. With the development of proteasome inhibitors, immunomodulatory drugs, monoclonal antibodies, chimeric antigen receptor T‐cell therapies, and novel agents, the survival of MM patients has been significantly improved. In addition, nanotechnology acts as both a nanocarrier and a treatment tool for MM. The properties and responsive conditions of nanomedicine can be tailored to reach different goals. Nanomedicine with a precise targeting property has offered great potential for drug delivery and assisted in tumor immunotherapy. In this review, we summarize the pathogenesis and current treatment options of MM, then overview recent advances in nanomedicine‐based systems, aiming to provide more insights into the treatment of MM.

Abnormal saccharides affecting cancer multi-drug resistance (MDR) and the reversal strategies

Clinically, chemotherapy is the mainstay in the treatment of multiple cancers. However, highly adaptable and activated survival signaling pathways of cancer cells readily emerge after long exposure to chemotherapeutics drugs, resulting in multi-drug resistance (MDR) and treatment failure. Recently, growing evidences indicate that the molecular action mechanisms of cancer MDR are closely associated with abnormalities in saccharides. In this review, saccharides affecting cancer MDR development are elaborated and analyzed in terms of aberrant aerobic glycolysis and its related enzymes, abnormal glycan structures and their associated enzymes, and glycoproteins. The reversal strategies including depletion of ATP, circumventing the original MDR pathway, activation by or inhibition of sugar-related enzymes, combination therapy with traditional cytotoxic agents, and direct modification on the sugar moiety, are ultimately proposed. It follows that abnormal saccharides have a significant effect on cancer MDR development, providing a new perspective for overcoming MDR and improving the outcome of chemotherapy.

Dose-dependent regulation of mitochondrial function and cell death pathway by sorafenib in liver cancer cells

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and the fourth most frequent cause of cancer-related death worldwide. Sorafenib is the first line recommended therapy for patients with locally advanced/metastatic HCC. The low response rate is attributed to intrinsic resistance of HCC cells to Sorafenib. The potential resistance to Sorafenib-induced cell death is multifactorial and involves all hallmarks of cancer. However, the presence of sub-therapeutic dose can negatively influence the antitumoral properties of the drug. In this sense, the present study showed that the sub-optimal Sorafenib concentration (10 nM) was associated with activation of caspase-9, AMP-activated protein kinase (AMPK), sustained autophagy, peroxisome proliferator-activated receptor-coactivator 1α (PGC-1α) and mitochondrial function in HepG2 cells. The increased mitochondrial respiration by Sorafenib (10 nM) was also observed in permeabilized HepG2 cells, but not in isolated rat mitochondria, which suggests the involvement of an upstream component in this regulatory mechanism. The basal glycolysis was dose dependently increased at early time point studied (6 h). Interestingly, Sorafenib increased nitric oxide (NO) generation that played an inhibitory role in mitochondrial respiration in sub-therapeutic dose of Sorafenib. The administration of sustained therapeutic dose of Sorafenib (10 µM, 24 h) induced mitochondrial dysfunction and dropped basal glycolysis derived acidification, as well as increased oxidative stress and apoptosis in HepG2. In conclusion, the accurate control of the administered dose of Sorafenib is relevant for the potential prosurvival or proapoptotic properties induced by the drug in liver cancer cells.

The role of autophagy in resistance to targeted therapies

Autophagy is a self-degradative cellular process, involved in stress response such as starvation, hypoxia, and oxidative stress. This mechanism balances macro-molecule recycling to regulate cell homeostasis. In cancer, autophagy play a role in the development and progression, while several studies describe it as one of the key processes in drug resistance. In the last years, in addition to standard anti-cancer treatments such as chemotherapies and irradiation, targeted therapy became one of the most adopted strategies in clinical practices, mainly due to high specificity and reduced side effects. However, similar to standard treatments, drug resistance is the main challenge in most patients. Here, we summarize recent studies that investigated the role of autophagy in drug resistance after targeted therapy in different types of cancers. We highlight positive results and limitations of pre-clinical and clinical studies in which autophagy inhibitors are used in combination with targeted therapies.

Autophagic cell death associated to Sorafenib in renal cell carcinoma is mediated through Akt inhibition in an ERK1/2 independent fashion

OBJECTIVES

To fully clarify the role of Mitogen Activated Protein Kinase in the therapeutic response to Sorafenib in Renal Cell Carcinoma as well as the cell death mechanism associated to this kinase inhibitor, we have evaluated the implication of several Mitogen Activated Protein Kinases in Renal Cell Carcinoma-derived cell lines.

MATERIALS AND METHODS

An experimental model of Renal Cell Carcinoma-derived cell lines (ACHN and 786-O cells) was evaluated in terms of viability by MTT assay, induction of apoptosis by caspase 3/7 activity, autophagy induction by LC3 lipidation, and p62 degradation and kinase activity using phospho-targeted antibodies. Knock down of ATG5 and ERK5 was performed using lentiviral vector coding specific shRNA.

RESULTS

Our data discard Extracellular Regulated Kinase 1/2 and 5 as well as p38 Mitogen Activated Protein Kinase pathways as mediators of Sorafenib toxic effect but instead indicate that the inhibitory effect is exerted through the PI3K/Akt signalling pathway. Furthermore, we demonstrate that inhibition of Akt mediates cell death associated to Sorafenib without caspase activation, and this is consistent with the induction of autophagy, as indicated by the use of pharmacological and genetic approaches.

CONCLUSION

The present report demonstrates that Sorafenib exerts its toxic effect through the induction of autophagy in an Akt-dependent fashion without the implication of Mitogen Activated Protein Kinase. Therefore, our data discard the use of inhibitors of the RAF-MEK-ERK1/2 signalling pathway in RCC and support the use of pro-autophagic compounds, opening new therapeutic opportunities for Renal Cell Carcinoma.

Old and Young Actors Playing Novel Roles in the Drama of Multiple Myeloma Bone Marrow Microenvironment Dependent Drug Resistance

Multiple myeloma (MM) is the second most frequent hematologic cancer. In addition to the deleterious effects of neoplastic plasma cell growth and spreading during the disease evolution, this tumor is characterized by the serious pathological consequences due to the massive secretion of monoclonal immunoglobulins and by the derangement of bone physiology with progressive weakening of the skeleton. Despite significant progresses having been made in the last two decades in the therapeutic management of this plasma cell tumor, MM remains invariably lethal, due to its extremely complex genetic architecture and to the constant protection it receives from the tumor niche, which is represented by the bone marrow microenvironment. While it is predictable that the discovery of novel therapies against the first of these two pathobiological features will take a longer time, the identification of the cellular and molecular mechanisms underlying the pro-growth effects of the myeloma milieu is a task that could lead to the development of novel treatments in a shorter timeframe. In this regard, aside from known “old” determinants of the cross-talk between bone marrow and MM cells, “young” cellular and molecular factors are now emerging, taking the scene of this complex neoplastic setting. In this review we aimed at giving insights on the latest evidence of potentially-targetable modes that MM cells exploit to increase fitness and gain a survival advantage. The benefits coming from the derangements of stress-managing pathways, autophagy, transcriptional rewiring, and non-coding RNAs are examples of such methods that MM cells utilize to escape cell death, but that hopefully will offer novel targets for the ever-increasing anti-MM therapeutic armamentarium.

Signaling Pathways and Emerging Therapies in Multiple Myeloma

Multiple myeloma (MM) is a devastating malignancy of antibody-producing plasma cells. In the absence of a single unifying genetic event contributing to disease manifestation, efforts have focused on understanding signaling events deregulated in myeloma plasma cells. MM cells are dependent on both cellular and non-cellular components of the tumor microenvironment such as bone marrow stromal cells, endothelial cells, and cytokines such as interleukin 6 (IL6), vascular endothelial growth factor (VEGF), and insulin-like growth factor (IGF) for their growth and survival. The cumulative effect of such interactions is the aberrant activation of numerous signal transduction pathways within the MM plasma cells leading to uncontrolled growth and prevention of apoptosis. Here, we will review our current understanding of some of the key signal transduction pathways dysregulated in MM and emerging therapies targeting these pathways in MM.

Preclinical activity of DCZ3301, a novel aryl-guanidino compound in the therapy of multiple myeloma

We synthesized a novel aryl-guanidino compound, DCZ3301, and found that it has potent cytotoxicity against multiple human cancer cell lines. The anticancer activity was most potent against multiple myeloma (MM). DCZ3301 induced cytotoxicity in MM cell lines, as well as patient myeloma cells, in part by decreasing mitochondrial membrane potential to induce apoptosis. In contrast, DCZ3301 had no cytotoxic effect on normal cells. DCZ3301 also inhibited cell cycling and caused a G2/M accumulation that corresponded with downregulation of Cdc25C, CDK1, and Cyclin B1. DCZ3301 retained its activity against MM cells in the presence of exogenous cytokines (IL-6 or VEGF) or bone marrow stromal cells (BMSCs) and reduced activity of multiple signaling pathways (STAT3, NFκB, AKT, ERK1/2) in MM but not normal cells. The STAT3 pathway played an important role in modulating DCZ3301-mediated cytotoxicity. Knockdown of STAT3 using siRNA in MM cells enhanced DCZ3301-induced cytotoxicity, whereas overexpression of STAT3 in MM cells partially protected them from apoptosis. In addition, DCZ3301 inhibited VEGF and IL-6 secretion in a dose-dependent fashion in a co-culture of MM cells and BMSCs. Combining DCZ3301 with bortezomib induced synergistic cytotoxicity in MM cell lines and primary MM cells. Finally, in vivo efficacy of DCZ3301 was confirmed in an MM xenograft mouse model. Together, these results provide a rationale for translation of this small-molecule inhibitor, either alone or in combination, to the clinic against MM.

Endoplasmic reticulum stress induces autophagy and apoptosis while inhibiting proliferation and drug resistance in multiple myeloma through the PI3K/Akt/mTOR signaling pathway

We investigated the effects of endoplasmic reticulum stress (ERS) on autophagy, proliferation, apoptosis, and drug resistance in multiple myeloma (MM). MM patients enrolled in our study (n = 268) were classified into sensitive and resistant groups based on chemotherapy efficacy, and their serum levels of β2-MG, albumin (ALB), lactic dehydrogenase (LDH), Ca²⁺ and hemoglobin were determined. In addition, human MM U266 and MOLP-2/R cells were divided into blank, tunicamycin (TM), TM + insulin-like growth factor-1 (IGF-1), and TM + rapamycin groups, and measured expression of ERS-related, PI3K/Akt/mTOR pathway-related, and autophagy-related mRNA and proteins. Serum levels of β2-MG, LDH and Ca2⁺, and expression of PI3K, Akt, and mTOR were higher in the resistant than sensitive group. Serum levels of ALB and hemoglobin, and expression of glucose-regulated protein 78 (GRP78), GRP94, microtubule associated protein 1 light chain 3 (LC3), and Beclin1, were lower in the resistant than sensitive group. In U266 cells treated with TM and IGF-1 or rapamycin, ERS promoted autophagy and apoptosis while inhibiting proliferation through inhibition of PI3K/Akt/mTOR signaling. ERS also reversed drug resistance in MOLP-2/R cells via the PI3K/Akt/mTOR signaling pathway. These data suggest that ERS activation could be exploited for therapeutic benefits in the treatment of MM.

Caspase-3-dependent cleavage of Bcl-xL in the stroma exosomes is required for their uptake by hematological malignant cells

The intercellular crosstalk between hematological malignancies and the tumor microenvironment is mediated by cell-to-cell interactions and soluble factors. One component of the secretome that is gaining increasing attention is the extracellular vesicles and, in particular, the exosomes. Apart from the role as vectors of molecular information, exosomes have been shown to possess intrinsic biological activity. In this study, we found that caspase-3 is activated in L88 bone marrow stroma cell-derived exosomes and identified 1 of the substrates to be the antiapoptotic protein Bcl-xL. The cleaved Bcl-xL is found in a panel of normal and cancer cell-derived exosomes and is localized on the outer leaflet of the exosomal membrane. Incubation of the exosomes with a caspase-3 inhibitor or the pan-caspase inhibitor prevents the cleavage of Bcl-xL. Importantly, MCF-7 cell-derived exosomes that are caspase-3-deficient are enriched in full-length Bcl-xL, whereas ectopic expression of caspase-3 restores the cleavage of Bcl-xL. Chemical inhibition of Bcl-xL with ABT737 or molecular inhibition by using the D61A and D76A Bcl-xL mutant leads to a significant decrease in the uptake of exosomes by hematopoietic malignant cells. These data indicate that the cleaved Bcl-xL is required for the uptake of exosomes by myeloma and lymphoma cells, leading to their increased proliferation. In summary, we demonstrate for the first time that Bcl-xL is an exosomal caspase-3 substrate and that this processing is required for the uptake of exosomes by recipient cells.

The clinical effect and relevant mechanism of combined sorafenib and radiofrequency ablation in the treatment of early small hepatocellular carcinoma

The number of cases with hepatocellular carcinoma (HCC) are on the increase. The aim of the present study was to investigate the clinical effect and relevant mechanism of combined sorafenib and radiofrequency ablation (RFA) in the treatment of the early small HCC. A total of 120 cases of patients with small HCC that presented during the period of May 2007 to June 2010 were selected and divided into the surgery (n=60) and RF (n=60) groups according to the treatment method employed. The surgery group was treated with a laparotomy resection and the RF group was treated with combined sorafenib and RFA, and a comparative analysis was made between the two groups with regard to recurrence rates, adverse reactions, and survival rates. After treatment of 1 month, the radical effective rate of the surgery and RF groups was 100%. Contrast-enhanced ultrasound images of the patients in the RF group were taken. During the 5-year follow-up, the tumor recurrence rate in the surgery group was 18.3%, significantly lower than that in the RF group where the tumor recurrence rate was 38.3% (P<0.05). The occurrence rate of postoperative pain, fever, abdominal bleeding, infection, and other complications of patients in the surgery group was significantly higher than the complication occurrence rate (P<0.05) of the patients in the RF group. The average survival time of the patients in the surgery group was 51.2±1.5 months and the survival rates during the first, third and fifth year were 90.7, 71.5 and 56.7%, respectively. Additionally, the average survival time of the patients in the RF group was 64.6±2.4 months and the survival rates during the first, third and fifth year were 91.1, 72.8 and 57.5%, respectively. The difference between the two groups was not statistically significant. The tumor-free survival rates in the surgery group during the first, third and fifth year were 87.8, 44.3 and 33.2%, respectively, while the tumor-free survival rates in the RF group during the first, third and fifth year were 86.2, 48.3 and 34.6%, respectively, and the difference between the two groups was not statistically significant. In conclusion, the combined sorafenib and RFA method, and laparotomy resection method have their advantages in the treatment of early small HCC, and under specific medical conditions, the former can partially replace the latter and be used as a preferred treatment means in the treatment of early small HCC.

Modulation of Autophagy by Sorafenib: Effects on Treatment Response

The multikinase inhibitor sorafenib is, at present, the only drug approved for the treatment of hepatocellular carcinoma (HCC), one of the most lethal types of cancer worldwide. However, the increase in the number of sorafenib tumor resistant cells reduces efficiency. A better knowledge of the intracellular mechanism of the drug leading to reduced cell survival could help to improve the benefits of sorafenib therapy. Autophagy is a bulk cellular degradation process activated in a broad range of stress situations, which allows cells to degrade misfolded proteins or dysfunctional organelles. This cellular route can induce survival or death, depending on cell status and media signals. Sorafenib, alone or in combination with other drugs is able to induce autophagy, but cell response to the drug depends on the complex integrative crosstalk of different intracellular signals. In cancerous cells, autophagy can be regulated by different cellular pathways (Akt-related mammalian target of rapamycin (mTOR) inhibition, 5′ AMP-activated protein kinase (AMPK) induction, dissociation of B-cell lymphoma 2 (Bcl-2) family proteins from Beclin-1), or effects of some miRNAs. Inhibition of mTOR signaling by sorafenib and diminished interaction between Beclin-1 and myeloid cell leukemia 1 (Mcl-1) have been related to induction of autophagy in HCC. Furthermore, changes in some miRNAs, such as miR-30α, are able to modulate autophagy and modify sensitivity in sorafenib-resistant cells. However, although AMPK phosphorylation by sorafenib seems to play a role in the antiproliferative action of the drug, it does not relate with modulation of autophagy. In this review, we present an updated overview of the effects of sorafenib on autophagy and its related activation pathways, analyzing in detail the involvement of autophagy on sorafenib sensitivity and resistance.

Sorafenib for the treatment of multiple myeloma

INTRODUCTION

Sorafenib is an orally available compound that acts predominantly by targeting the Ras/Raf/MEK/ERK pathway and by inhibiting the vascular endothelial growth factor (VEGF). Since the Ras/Raf/MEK/ERK pathway is implicated in the proliferation of multiple myeloma (MM) cells and VEGF in bone marrow neovascularization, sorafenib is a drug offering the potential for targeting two important pathogenetic mechanisms involved in MM. Thus, sorafenib is being proposed for use in MM.

AREAS COVERED

In this review, the authors discuss the rationale for the use of sorafenib in MM. They then summarize the clinical development of sorafenib in MM, from initial Phase I to Phase II studies. A systematic literature review of the trials was performed using PubMed.

EXPERT OPINION

Preliminary data from phase I/II trials showed that sorafenib had a good safety profile but minimal anti-myeloma activity as a single agent in relapsed/refractory patients. Results of phase II trials, evaluating sorafenib combined with new drugs, such as bortezomib and lenalidomide are eagerly awaited.

Analysis of Tyrosine Kinase Inhibitor-Mediated Decline in Contractile Force in Rat Engineered Heart Tissue

Introduction

Left ventricular dysfunction is a frequent and potentially severe side effect of many tyrosine kinase inhibitors (TKI). The mode of toxicity is not identified, but may include impairment of mitochondrial or sarcomeric function, autophagy or angiogenesis, either as an on-target or off-target mechanism.

Methods and Results

We studied concentration-response curves and time courses for nine TKIs in three-dimensional, force generating engineered heart tissue (EHT) from neonatal rat heart cells. We detected a concentration- and time-dependent decline in contractile force for gefitinib, lapatinib, sunitinib, imatinib, sorafenib, vandetanib and lestaurtinib and no decline in contractile force for erlotinib and dasatinib after 96 hours of incubation. The decline in contractile force was associated with an impairment of autophagy (LC3 Western blot) and appearance of autophagolysosomes (transmission electron microscopy).

Conclusion

This study demonstrates the feasibility to study TKI-mediated force effects in EHTs and identifies an association between a decline in contractility and inhibition of autophagic flux.

Trial Watch-Oncolytic viruses and cancer therapy

Oncolytic virotherapy relies on the administration of non-pathogenic viral strains that selectively infect and kill malignant cells while favoring the elicitation of a therapeutically relevant tumor-targeting immune response. During the past few years, great efforts have been dedicated to the development of oncolytic viruses with improved specificity and potency. Such an intense wave of investigation has culminated this year in the regulatory approval by the US Food and Drug Administration (FDA) of a genetically engineered oncolytic viral strain for use in melanoma patients. Here, we summarize recent preclinical and clinical advances in oncolytic virotherapy.

Thromboxane A2 Receptor Inhibition Suppresses Multiple Myeloma Cell Proliferation by Inducing p38/c-Jun N-terminal Kinase (JNK) Mitogen-activated Protein Kinase (MAPK)-mediated G2/M Progression Delay and Cell Apoptosis

Multiple myeloma (MM) is a plasma cell malignancy without effective therapeutics. Thromboxane A2 (TxA2)/TxA2 receptor (T prostanoid receptor (TP)) modulates the progression of some carcinomas; however, its effects on MM cell proliferation remain unclear. In this study, we evaluated cyclooxygenase (COX) enzymes and downstream prostaglandin profiles in human myeloma cell lines RPMI-8226 and U-266 and analyzed the effects of COX-1/-2 inhibitors SC-560 and NS-398 on MM cell proliferation. Our observations implicate COX-2 as being involved in modulating cell proliferation. We further incubated MM cells with prostaglandin receptor antagonists or agonists and found that only the TP antagonist, SQ29548, suppressed MM cell proliferation. TP silencing and the TP agonist, U46619, further confirmed this finding. Moreover, SQ29548 and TP silencing promoted MM cell G2/M phase delay accompanied by reducing cyclin B1/cyclin-dependent kinase-1 (CDK1) mRNA and protein expression. Notably, cyclin B1 overexpression rescued MM cells from G2/M arrest. We also found that the TP agonist activated JNK and p38 MAPK phosphorylation, and inhibitors of JNK and p38 MAPK depressed U46619-induced proliferation and cyclin B1/CDK1 protein expression. In addition, SQ29548 and TP silencing led to the MM cell apoptotic rate increasing with improving caspase 3 activity. The knockdown of caspase 3 reversed the apoptotic rate. Taken together, our results suggest that TxA2/TP promotes MM cell proliferation by reducing cell delay at G2/M phase via elevating p38 MAPK/JNK-mediated cyclin B1/CDK1 expression and hindering cell apoptosis. The TP inhibitor has potential as a novel agent to target kinase cascades for MM therapy.

Targeting the Bone Marrow Microenvironment

Unprecedented advances in multiple myeloma (MM) therapy during the last 15 years are predominantly based on our increasing understanding of the pathophysiologic role of the bone marrow (BM) microenvironment. Indeed, new treatment paradigms, which incorporate thalidomide, immunomodulatory drugs (IMiDs), and proteasome inhibitors, target the tumor cell as well as its BM microenvironment. Ongoing translational research aims to understand in more detail how disordered BM-niche functions contribute to MM pathogenesis and to identify additional derived targeting agents. One of the most exciting advances in the field of MM treatment is the emergence of immune therapies including elotuzumab, daratumumab, the immune checkpoint inhibitors, Bispecific T-cell engagers (BiTes), and Chimeric antigen receptor (CAR)-T cells. This chapter will review our knowledge on the pathophysiology of the BM microenvironment and discuss derived novel agents that hold promise to further improve outcome in MM.

Trial Watch-Immunostimulation with cytokines in cancer therapy

During the past decade, great efforts have been dedicated to the development of clinically relevant interventions that would trigger potent (and hence potentially curative) anticancer immune responses. Indeed, developing neoplasms normally establish local and systemic immunosuppressive networks that inhibit tumor-targeting immune effector cells, be them natural or elicited by (immuno)therapy. One possible approach to boost anticancer immunity consists in the (generally systemic) administration of recombinant immunostimulatory cytokines. In a limited number of oncological indications, immunostimulatory cytokines mediate clinical activity as standalone immunotherapeutic interventions. Most often, however, immunostimulatory cytokines are employed as immunological adjuvants, i.e., to unleash the immunogenic potential of other immunotherapeutic agents, like tumor-targeting vaccines and checkpoint blockers. Here, we discuss recent preclinical and clinical advances in the use of some cytokines as immunostimulatory agents in oncological indications.

Molecular mechanisms in multiple myeloma drug resistance

Multiple myeloma (MM) is predominantly an incurable malignancy despite high-dose chemotherapy, autologous stem cell transplant and novel agents. MM is a genetically heterogeneous disease and the complexity increases as the disease progresses to a more aggressive stage. MM arises from a plasma cell, which produces and secretes non-functioning immunoglobulins. Most MM cells are sensitive to proteasome inhibitors (PIs), which have become the main drug in the treatment of newly diagnosed and relapsed MM. However, not all MM is sensitive to PIs. This review summarises the literature regarding molecular biology of MM with a focus on the unfolded protein response and explores how this could affect drug sensitivity and progression of disease.

Trial Watch: Proteasomal inhibitors for anticancer therapy

The so-called "ubiquitin-proteasome system" (UPS) is a multicomponent molecular apparatus that catalyzes the covalent attachment of several copies of the small protein ubiquitin to other proteins that are generally (but not always) destined to proteasomal degradation. This enzymatic cascade is crucial for the maintenance of intracellular protein homeostasis (both in physiological conditions and in the course of adaptive stress responses), and regulates a wide array of signaling pathways. In line with this notion, defects in the UPS have been associated with aging as well as with several pathological conditions including cardiac, neurodegenerative, and neoplastic disorders. As transformed cells often experience a constant state of stress (as a result of the hyperactivation of oncogenic signaling pathways and/or adverse microenvironmental conditions), their survival and proliferation are highly dependent on the integrity of the UPS. This rationale has driven an intense wave of preclinical and clinical investigation culminating in 2003 with the approval of the proteasomal inhibitor bortezomib by the US Food and Drug Administration for use in multiple myeloma patients. Another proteasomal inhibitor, carfilzomib, is now licensed by international regulatory agencies for use in multiple myeloma patients, and the approved indications for bortezomib have been extended to mantle cell lymphoma. This said, the clinical activity of bortezomib and carfilzomib is often limited by off-target effects, innate/acquired resistance, and the absence of validated predictive biomarkers. Moreover, the antineoplastic activity of proteasome inhibitors against solid tumors is poor. In this Trial Watch we discuss the contribution of the UPS to oncogenesis and tumor progression and summarize the design and/or results of recent clinical studies evaluating the therapeutic profile of proteasome inhibitors in cancer patients.

Trial Watch: Immunogenic cell death inducers for anticancer chemotherapy

The term "immunogenic cell death" (ICD) is now employed to indicate a functionally peculiar form of apoptosis that is sufficient for immunocompetent hosts to mount an adaptive immune response against dead cell-associated antigens. Several drugs have been ascribed with the ability to provoke ICD when employed as standalone therapeutic interventions. These include various chemotherapeutics routinely employed in the clinic (e.g., doxorubicin, epirubicin, idarubicin, mitoxantrone, bleomycin, bortezomib, cyclophosphamide and oxaliplatin) as well as some anticancer agents that are still under preclinical or clinical development (e.g., some microtubular inhibitors of the epothilone family). In addition, a few drugs are able to convert otherwise non-immunogenic instances of cell death into bona fide ICD, and may therefore be employed as chemotherapeutic adjuvants within combinatorial regimens. This is the case of cardiac glycosides, like digoxin and digitoxin, and zoledronic acid. Here, we discuss recent developments on anticancer chemotherapy based on ICD inducers.

Emerging Therapeutic Strategies for Overcoming Proteasome Inhibitor Resistance

The debut of the proteasome inhibitor bortezomib (Btz; Velcade®) radically and immediately improved the treatment of multiple myeloma (MM), an incurable malignancy of the plasma cell. Therapeutic resistance is unavoidable, however, and represents a major obstacle to maximizing the clinical potential of the drug. To address this challenge, studies have been conducted to uncover the molecular mechanisms driving Btz resistance and to discover new targeted therapeutic strategies and combinations that restore Btz activity. This review discusses the literature describing molecular adaptations that confer Btz resistance with a primary disease focus on MM. Also discussed are the most recent advances in therapeutic strategies that overcome resistance, approaches that include redox-modulating agents, murine double minute 2 inhibitors, therapeutic monoclonal antibodies, and new epigenetic-targeted drugs like bromodomain and extra terminal domain inhibitors.

The IGF-1 receptor inhibitor picropodophyllin potentiates the anti-myeloma activity of a BH3-mimetic

The ABT-analogous 737, 263 and 199 are BH3 mimetics showing potent anti-myeloma (MM) activity, but only on defined molecular subgroups of MM patients presenting a Bcl-2high/Mcl-1low profile. IGF-1 is a major survival factor in MM regulating the expression of Bcl-2 proteins and might therefore be a resistance factor to these ABT-analogous. We first show that IGF-1 protected human MM cell lines (HMCLs) against ABT-737. Concurrently, the IGF-1 receptor inhibitor picropodophyllin (PPP) synergistically sensitized HMCL, primary human MM and murine 5T33MM cells to ABT-737 and ABT-199 by further decreasing cell viability and enhancing apoptosis. Knockdown of Bcl-2 by shRNA protected MM cells to ABT-737, while Mcl-1 shRNA sensitized the cells. PPP overcame the Bcl-2 dependency of ABT-737, but failed to completely overcome the protective effect of Mcl-1. In vivo, co-treatment of 5T33MM bearing mice significantly decreased tumor burden and prolonged overall survival both in a prophylactic and therapeutic setting. Interestingly, proteasome inhibitor resistant CD138- 5T33MM cells were more sensitive to ABT-737, whereas PPP alone targeted the CD138+ cells more effectively. After co-treatment, both subpopulations were targeted equally. Together, the combination of an IGF-1R inhibitor and an ABT-analogue displays synergistic anti-myeloma activity providing the rational for further (pre)clinical testing.

Serial low doses of sorafenib enhance therapeutic efficacy of adoptive T cell therapy in a murine model by improving tumor microenvironment

Requirements of large numbers of transferred T cells and various immunosuppressive factors and cells in the tumor microenvironment limit the applications of adoptive T cells therapy (ACT) in clinic. Accumulating evidences show that chemotherapeutic drugs could act as immune supportive instead of immunosuppressive agents when proper dosage is used, and combined with immunotherapy often results in better treatment outcomes than monotherapy. Controversial immunomodulation effects of sorafenib, a multi-kinases inhibitor, at high and low doses have been reported in several types of cancer. However, what is the range of the low-dose sorafenib will influence the host immunity and responses of ACT is still ambiguous. Here we used a well-established E.G7/OT-1 murine model to understand the effects of serial low doses of sorafenib on both tumor microenvironment and transferred CD8+ T cells and the underlying mechanisms. Sorafenib lowered the expressions of immunosuppressive factors, and enhanced functions and migrations of transferred CD8+ T cells through inhibition of STAT3 and other immunosuppressive factors. CD8+ T cells were transduced with granzyme B promoter for driving imaging reporters to visualize the activation and distribution of transferred CD8+ T cells prior to adoptive transfer. Better activations of CD8+ T cells and tumor inhibitions were found in the combinational group compared with CD8+ T cells or sorafenib alone groups. Not only immunosuppressive factors but myeloid derived suppressive cells (MDSCs) and regulatory T cells (Tregs) were decreased in sorafenib-treated group, indicating that augmentation of tumor inhibition and function of CD8+ T cells by serial low doses of sorafenib were via reversing the immunosuppressive microenvironment. These results revealed that the tumor inhibitions of sorafenib not only through eradicating tumor cells but modifying tumor microenvironment, which helps outcomes of ACT significantly.

In comparative analysis of multi-kinase inhibitors for targeted medulloblastoma therapy pazopanib exhibits promising in vitro and in vivo efficacy

Regardless of the recent advances in cytotoxic therapies, 30% of children diagnosed with medulloblastoma. succumb to the disease. Therefore, novel therapeutic approaches are warranted. Here we demonstrate that Pazopanib a clinically approved multi-kinase angiogenesis inhibitor (MKI) inhibits proliferation and apoptosis in medulloblastoma cell lines. Moreover, Pazopanib profoundly attenuates medulloblastoma cell migration, a prerequisite for tumor invasion and metastasis. In keeping with the observed anti-neoplastic activity of Pazopanib, we also delineate reduced phosphorylation of the STAT3 protein, a key regulator of medulloblastoma proliferation and cell survival. Finally, we document profound in vivo activity of Pazopanib in an orthotopic mouse model of the most aggressive c-myc amplified human medulloblastoma variant. Pazopanib reduced the growth rate of intracranial growing medulloblastoma and significantly prolonged the survival. Furthermore, to put these results into a broader perspective we analysed Pazopanib side by side with the MKI Sorafenib. Both compounds share a similar target profile but display different pharmacodynamics and pharmacokinetics with distinct cytotoxic activity in different tumor entities. Thus, we identified Pazopanib as a new promising candidate for a rational clinical assessment for targeted paediatric medulloblastoma therapy.

Two death pathways induced by sorafenib in myeloma cells: Puma-mediated apoptosis and necroptosis

PURPOSE

Sorafenib is a multikinase inhibitor that targets the MAPK pathway and is currently used for the treatment of hepatocellular and renal carcinoma. Recently, it has been shown that sorafenib is also cytotoxic to multiple myeloma (MM) cells. Here, we have further analyzed the mechanism of sorafenib-induced death in MM cells.

METHODS

Cell death induced by sorafenib in MM cell lines and in plasma cells from MM patients was evaluated by analysis of gene expression by RT-MLPA and quantitative PCR, protein levels and functionality by Western blot and flow cytometry and gene silencing with siRNA.

RESULTS

Cell death was characterized by phosphatidylserine exposure, ΔΨm loss, cytochrome c release and caspase activation, hallmarks of apoptosis. DL50 at 24 h ranged from 6 to 10 µM. Ex vivo treatment with 20 µM sorafenib induced apoptosis in around 80 % myeloma cells from six multiple myeloma patients. Sorafenib induced caspase-dependent degradation of Bcl-xL and Mcl-1 proteins, destabilizing the mitochondria and speeding up the development of apoptosis. Sorafenib treatment increased levels of Puma at mRNA and protein level and gene silencing with siRNA confirmed a relevant role for Puma in the induction of apoptosis. Co-treatment with the pan-caspase inhibitor Z-VAD-fmk prevented cell death to a variable degree depending on the cell line. In RPMI 8226 cells, Z-VAD-fmk prevented most of sorafenib-induced death. However, death in MM.1S was only prevented by co-incubation with both Z-VAD-fmk and the RIP1K inhibitor necrostatin-1, indicating that under conditions of inefficient caspase activation, sorafenib induces death by necroptosis.

CONCLUSION

Our results demonstrate a key role for Puma in the triggering of sorafenib-induced apoptosis and that this drug can also induce death by necroptosis in multiple myeloma cells.

Chloroquine and hydroxychloroquine for cancer therapy

Macroautophagy (herein referred to as autophagy) is a highly conserved mechanism for the lysosomal degradation of cytoplasmic components. Autophagy is critical for the maintenance of intracellular homeostasis, both in baseline conditions and in the context of adaptive responses to stress. In line with this notion, defects in the autophagic machinery have been etiologically associated with various human disorders including infectious, inflammatory and neoplastic conditions. Once tumors are established, however, autophagy sustains the survival of malignant cells, hence representing an appealing target for the design of novel anticancer regimens. Accordingly, inhibitors of autophagy including chloroquine and hydroxychloroquine have been shown to mediate substantial antineoplastic effects in preclinical models, especially when combined with chemo- or radiotherapeutic interventions. The pharmacological profile of chloroquine and hydroxychloroquine, however, appear to involve mechanisms other than autophagy inhibition. Here, we discuss the dual role of autophagy in oncogenesis and tumor progression, and summarize the results or design of clinical studies recently completed or initiated to evaluate the therapeutic activity of chloroquine derivatives in cancer patients.

Autophagy in blood cancers: biological role and therapeutic implications

Autophagy is a cell recycling process the molecular apparatus of which has been identified over the past decade. Autophagy allows cells to survive starvation and inhospitable conditions and plays a key role in numerous physiological functions, including hematopoiesis and immune responses. In hematologic malignancies, autophagy can either act as a chemo-resistance mechanism or have tumor suppressive functions, depending on the context. In addition, autophagy is involved in other important aspects of blood cancers as it promotes immune competence and anti-cancer immunity, and may even help enhance patient tolerance to standard treatments. Approaches exploiting autophagy, either to activate or inhibit it, could find broad application in hematologic malignancies and contribute to improved clinical outcomes. These aspects are discussed here together with a brief introduction to the molecular machinery of autophagy and to its role in blood cell physiology.

A phase II trial of BAY 43-9006 (sorafenib) (NSC-724772) in patients with relapsing and resistant multiple myeloma: SWOG S0434

The authors assessed the overall response rate, including confirmed complete response (CR) and partial response, in patients with relapsed/refractory multiple myeloma treated with sorafenib. Qualitative and quantitative toxicities associated with this regimen were evaluated. Patients were eligible if they had a confirmed diagnosis of refractory or relapsed (RR) multiple myeloma (MM) with measurable monoclonal protein. Patients had to have adequate renal, hepatic, hematologic, and cardiac function with a Zubrod performance status of 0–2. Patients were given 400 mg sorafenib by mouth twice daily for 28-day treatment cycles. These patients were followed up for a maximum of 3 years to assess responses and adverse events. Twenty-three patients were enrolled. Of these, five were found to be ineligible for the following reasons: four had insufficient documentation of the baseline disease and one patient did not have measurable disease. All eighteen eligible patients were evaluable for toxicities. Three patients experienced grade 4 toxicities: one with thrombocytopenia, one with anemia, and one with renal failure. Four of the eighteen eligible patients were not assessable for response due to removal from protocol treatment prior to adequate disease assessment. Specifically, three were removed for either grade 4 toxicity or progression of disease and one was removed per patient choice (due to reasons unrelated to treatment). Of the 18 patients who were assessed for toxicities, 5 (27.8%) received at least one fully dosed cycle, 2 (11.1%) of whom had all cycles fully dosed. No responses were observed on this study of the 14 patients who were assessable for response. All patients have discontinued protocol treatment as of August 2008. Overall survival at 12 months was 50% (95% CI 27–73%) and median progression-free survival was 1.2 months (95% CI 1.0–5.4). The trial did not exhibit activity by the International Uniform Response Criteria for MM. Further research should focus on combination therapy of sorafenib with standard treatments in selected patients with RR MM.

Trial Watch: Adoptive cell transfer for anticancer immunotherapy

The expression "adoptive cell transfer" (ACT) is commonly employed to indicate an immunotherapeutic regimen involving the isolation of autologous blood-borne or tumor-infiltrating lymphocytes, their selection/expansion/activation ex vivo, and their reinfusion into the patient, most often in the context of lymphodepleting pre-conditioning and in combination with immunostimulatory treatments. Optionally, the cellular material for ACT is genetically manipulated before expansion to (1) target specific tumor-associated antigens; (2) endogenously express immunostimulatory molecules; and/or (3) persist for long periods upon reinfusion. Consistent efforts have been dedicated at the amelioration of this immunotherapeutic regimen throughout the past decade, resulting in the establishment of ever more efficient and safer ACT protocols. Accordingly, the number of clinical trials testing ACT in oncological indications does not cease to increase. In this Trial Watch, we summarize recent developments in this exciting area of research, covering both high-impact studies that have been published during the last 12 months and clinical trials that have been launched in the same period to evaluate the safety and therapeutic potential of ACT in cancer patients.

Do anti-angiogenic cancer therapies increase risk of significant weight loss?

INTRODUCTION

Angiogenesis is important in many disease states such as cancer. Anti-angiogenic cancer drugs are in broad use for the treatment of cancers. However, currently most of these anticancer drugs result in some adverse effects in the patient.

AREAS COVERED

In this paper, we review evidence on the association between anti-angiogenic therapies and weight loss. We report on basic experiments and clinical trials that measure weight loss with anti-angiogenic cancer therapies.

EXPERT OPINION

Few strong associations are found between anti-angiogenic cancer therapies and weight loss, with the exception of some multikinase inhibitors in clinical trials. Anti-angiogenic cancer therapies appear safe in relation to weight loss, but the result needs to be established by further clinical trials.

Trial Watch: Chemotherapy with immunogenic cell death inducers

Accumulating evidence suggests that the clinical efficacy of selected anticancer drugs, including conventional chemotherapeutics as well as targeted anticancer agents, originates (at least in part) from their ability to elicit a novel or reinstate a pre-existing tumor-specific immune response. One of the mechanisms whereby chemotherapy can stimulate the immune system to recognize and destroy malignant cells is commonly known as immunogenic cell death (ICD). Cancer cells succumbing to ICD are de facto converted into an anticancer vaccine and as such elicit an adaptive immune response. Several common chemotherapeutics share the ability of triggering ICD, as demonstrated in vaccination experiments relying on immunocompetent mice and syngeneic cancer cells. A large number of ongoing clinical trials involve such ICD inducers, often (but not always) as they are part of the gold standard therapeutic approach against specific neoplasms. In this Trial Watch, we summarize the latest advances on the use of cyclophosphamide, doxorubicin, epirubicin, oxaliplatin, and mitoxantrone in cancer patients, discussing high-impact studies that have been published during the last 13 months as well as clinical trials that have been initiated in the same period to assess the antineoplastic profile of these immunogenic drugs as off-label therapeutic interventions.

Inhibitory role of the small leucine-rich proteoglycan biglycan in bladder cancer

BACKGROUND

Urothelial bladder cancer is the ninth most common cancer. Despite surgical and chemotherapeutic treatment the prognosis is still poor once bladder cancer progresses to a muscle-invasive state. Discovery of new diagnostic markers and pathophysiologic effectors might help to contribute to novel diagnostic and therapeutic options. The extracellular matrix microenvironment shaped by the extracellular matrix critically affects tumor cell and stroma cell functions. Therefore, aim of the present study was to assess the possible implication of the small leucine-rich proteoglycan biglycan in progression of human urothelial bladder cancer.

METHODS AND RESULTS

For this purpose tumor biopsies of 76 bladder cancer patients with different tumor stages (pTa, pT1-T4) were investigated with respect to biglycan expression and correlated with a long-term (10 years) clinical follow-up. Interestingly, higher biglycan mRNA expression was associated with higher tumor stages and muscle invasiveness. In vitro knock-down of endogenous biglycan in human urothelial carcinoma cells (J82 cells) increased proliferation, whereas addition of recombinant biglycan and overexpression of biglycan inhibited tumor cell proliferation. In line with this growth-inhibitory effect of biglycan, transplantation of J82 cells after knock-down of biglycan resulted in significantly increased growth of subcutaneous xenograft tumors in nude mice in vivo. Furthermore, treatment with two anti-proliferative, multi-receptor tyrosine kinase inhibitors-sunitinib and sorafenib-strongly upregulated biglycan expression. Collectively, the experimental data suggest that high biglycan expression is associated with reduced tumor cell proliferation. In accordance, Kaplan-Meier analysis revealed higher 10-year survival in patients with high biglycan mRNA expression in tumor biopsies.

CONCLUSION

In conclusion, the present data suggest that biglycan is an endogenous inhibitor of bladder cancer cell proliferation that is upregulated in response to anti-proliferative tyrosine kinase inhibitors. In addition, high biglycan expression is associated with favorable prognosis.

Combined inhibition of p97 and the proteasome causes lethal disruption of the secretory apparatus in multiple myeloma cells

Inhibition of the proteasome is a widely used strategy for treating multiple myeloma that takes advantage of the heavy secretory load that multiple myeloma cells (MMCs) have to deal with. Resistance of MMCs to proteasome inhibition has been linked to incomplete disruption of proteasomal endoplasmic-reticulum (ER)-associated degradation (ERAD) and activation of non-proteasomal protein degradation pathways. The ATPase p97 (VCP/Cdc48) has key roles in mediating both ERAD and non-proteasomal protein degradation and can be targeted pharmacologically by small molecule inhibition. In this study, we compared the effects of p97 inhibition with Eeyarestatin 1 and DBeQ on the secretory apparatus of MMCs with the effects induced by the proteasome inhibitor bortezomib, and the effects caused by combined inhibition of p97 and the proteasome. We found that p97 inhibition elicits cellular responses that are different from those induced by proteasome inhibition, and that the responses differ considerably between MMC lines. Moreover, we found that dual inhibition of both p97 and the proteasome terminally disrupts ER configuration and intracellular protein metabolism in MMCs. Dual inhibition of p97 and the proteasome induced high levels of apoptosis in all of the MMC lines that we analysed, including bortezomib-adapted AMO-1 cells, and was also effective in killing primary MMCs. Only minor toxicity was observed in untransformed and non-secretory cells. Our observations highlight non-redundant roles of p97 and the proteasome in maintaining secretory homeostasis in MMCs and provide a preclinical conceptual framework for dual targeting of p97 and the proteasome as a potential new therapeutic strategy in multiple myeloma.

2-Deoxyglucose treatment complements the cisplatin- or BH3-only mimetic-induced suppression of neuroblastoma cell growth

Neuroblastoma (NB) is characterized by pleomorphic molecular characteristics, which may influence cellular metabolism as well as the efficacy of glycolytic inhibitors in suppressing NB cell growth. We studied the metabolic profile of four NB cell lines without or with MYCN amplification and found no unanimous metabolic characteristics. The two NB cell lines with MYCN amplification exhibited a significantly higher HIF-1α expression level and ATP content compared to the two cell lines without MYCN amplification. MYCN amplification was associated with significantly greater inhibition of cellular proliferation and more apoptosis after treatment with the glycolytic inhibitor 2-deoxyglucose (2DG). Further analysis showed that 2DG decreased both PDK1 and the ATP content. [corrected]. In addition, 2DG decreased hexokinase II expression in SK-N-DZ cells and increased HIF-1α, Noxa, and PUMA expression in SK-N-AS cells. Pretreating SK-N-DZ cells with 2DG or cisplatin for 24 h, followed by cisplatin or 2DG for another 24 h, resulted in significantly greater suppression of cellular proliferation compared to treatment with 2DG or cisplatin for 48 h alone. Effective suppression of SK-N-AS proliferation occurred only when the cells were pretreated with cisplatin. Pretreatment of SK-N-DZ, but not SK-N-AS, with 2DG followed by the BH3-only mimetic ABT737 also resulted in significantly greater suppression of cellular proliferation compared to treatment with ABT737 or 2DG alone. A low dose of 2DG (2mM) was as effective as a high dose (20mM) in SK-N-DZ cells. In conclusion, the glycolytic inhibitor 2DG complemented the cisplatin- or ABT737-induced suppression of growth in NB cells, which are sensitive to glycolytic inhibition.