Identification of human S100A9 as a novel target for treatment of autoimmune disease via binding to quinoline-3-carboxamides

Tumour-induced immune suppression: role of inflammatory mediators released by myelomonocytic cells

Tumour-induced immune dysfunction is a serious challenge to immunotherapy for cancer, and intact adaptive and innate cellular immunity is key to its success. Myelomonocytic cells have a central role in this immune suppression, and tumour-associated macrophages, eosinophils, neutrophils and myeloid-derived suppressor cells have all been shown to be of major importance. These myelomonocytic cells secrete a broad repertoire of inflammatory mediators providing them with powerful tools to inhibit tumour-reactive T cells and natural killer cells; free oxygen radicals including reactive oxygen species and NO, arginase, indoleamine 2,3-dioxygenase, prostaglandins, the pro-inflammatory heterodimer S100A8/9 and cytokines, such as granulocyte-macrophage colony-stimulating factor and transforming growth factor-β, have proven particularly potent in suppressing antitumour cellular immunity. Determining which of these factors prevail in individual cancer patients and designing methods aimed at neutralization or inhibition of their effects on target tissues have the potential to greatly enhance the clinical efficacy of immunotherapy.

Defining a role for laquinimod in multiple sclerosis

Multiple sclerosis (MS), an inflammatory disease affecting the central nervous system, is considered to exhibit an important neurodegenerative component as well. Laquinimod is an orally administered quinoline-3-carboxamide under development for the treatment of MS. In vitro and animal studies have revealed various mechanisms by which laquinimod may exert its effects on the immune and nervous systems. These include effects on the innate immune system that promote the differentiation of anti-inflammatory/regulatory T cells, the activation of microglia cells, an increase in the expression of brain-derived neurotrophic factor, as well as the prevention of inflammation-induced excitotoxicity. Two phase III studies revealed the clinical benefits of laquinimod in patients with relapsing-remitting MS and exhibited a benign safety profile for this drug. Ongoing clinical trials will help to define the optimal dose and indication for laquinimod in MS. This article reviews current experimental and clinical evidence on the role of laquinimod in patients with this disabling disease.

Quantitative determination of the anti-tumor agent tasquinimod in human urine by liquid chromatography-tandem mass spectrometry

Tasquinimod is an anti-tumor drug that is currently in clinical development for the treatment of solid cancers. After oral administration, tasquinimod and a number of its metabolites are excreted in the urine. The quantitative determination of tasquinimod in urine is challenging because of the required sensitivity (down to 0.1nM or 40pg/mL), the highly variable nature of this biological matrix and the presence of potentially unstable metabolites, which may convert back to the parent drug. In this article, an LC-MS/MS method is described for the determination of tasquinimod in human urine in the concentration range 0.1-200nM. Liquid-liquid extraction with n-chlorobutane was used to extract tasquinimod from 100μL human urine and to remove interfering endogenous urinary constituents. Reversed-phase liquid chromatography coupled to a triple quadrupole mass spectrometer equipped with an ESI source was used for quantification of tasquinimod in a 2.5-min run. A stable-isotope labeled internal standard was used for response normalization. The intra- and inter-day coefficients of variation (precision) as well as the bias (accuracy) of the method were below 7%. Although considerable conversion of conjugated tasquinimod metabolites back to parent drug was observed when incurred samples were stored at 37°C for a prolonged time, tasquinimod as well as its metabolites were sufficiently stable under all relevant sampling, storage and analysis conditions. The method was successfully applied to determine the urinary excretion of tasquinimod in healthy volunteers and patients with renal impairment after a 0.5-mg oral dose.

Tasquinimod: a novel drug in advanced prostate cancer

Tasquinimod, an oral quinolone-3-carboxamide with anti-tumor activity in preclinical models of prostate cancer, has been tested in patients with minimally symptomatic castration-resistant prostate cancer (CRPC), showing promising inhibitory effects on the occurrence of metastasis and delayed disease progression. Although its mode of action is not fully understood, tasquinimod presumably exerts its unique anti-tumor action through inhibition of angiogenesis and immunomodulation. In clinical studies, tasquinimod demonstrated anti-tumor activity in prostate cancer in combination with a mild-to-moderate side effect profile. With single-agent tasquinimod, dose-limiting toxicity was amylase elevation without signs of pancreatitis and sinus tachycardia. The maximum tolerated dose in Phase I studies in patients with CRPC was once daily administration of 0.5-1-mg tasquinimod orally. In a Phase II trial, significant clinical activity has been demonstrated in asymptomatic or minimally symptomatic, chemotherapy-naive, metastatic CRPC (mCRPC) patients. Men were randomized to tasquinimod or placebo in a 2:1 fashion; treatment with tasquinimod resulted in significant improvement of median progression-free survival (7.6 vs 3.3 months with placebo; p = 0.0042). Based on these encouraging effects, a randomized, double-blind, placebo-controlled trial in men with minimally symptomatic mCRPC has been designed. This large Phase III trial, powered for a primary end point of progression-free survival, has now enrolled the target number of 1200 men. If the Phase II data are validated in the Phase III trial a new compound with a unique mode of action might become approved as a future therapy for minimally symptomatic mCRPC patients.

Functional characterization of S100A8 and S100A9 in altering monolayer permeability of human umbilical endothelial cells

S100A8, S100A9 and S100A8/A9 complexes have been known as important endogenous damage-associated molecular pattern (DAMP) proteins. But the pathophysiological roles of S100A8, S100A9 and S100A8/A9 in cardiovascular diseases are incompletely explained. In this present study, the effects of homo S100A8, S100A9 and their hetero-complex S100A8/A9 on endothelial barrier function were tested respectively in cultured human umbilical venous endothelial cells (HUVECs). The involvement of TLR4 and RAGE were observed by using inhibitor of TLR4 and blocking antibody of RAGE. The clarification of different MAPK subtypes in S100A8/A9-induced endothelial response was implemented by using specific inhibitors. The calcium-dependency was detected in the absence of Ca²⁺ or in the presence of gradient-dose Ca²⁺. The results showed that S100A8, S100A9 and S100A8/A9 could induce F-actin and ZO-1 disorganization in HUVECs and evoked the increases of HUVEC monolayer permeability in a dose- and time-dependent manner. The effects of S100A8, S100A9 and S100A8/A9 on endothelial barrier function depended on the activation of p38 and ERK1/2 signal pathways through receptors TLR4 and RAGE. Most importantly, we revealed the preference of S100A8 on TLR4 and S100A9 on RAGE in HUVECs. The results also showed the calcium dependency in S100A8- and S100A9-evoked endothelial response, indicating that calcium dependency on formation of S100A8 or A9 dimmers might be the prerequisite for this endothelial functional alteration.

Mechanism of action and clinical activity of tasquinimod in castrate-resistant prostate cancer

Castrate-resistant prostate cancer (CRPC) is a disease where survival is poor and treatment is challenging. Over the past 3 years, significant advances in the field have been made with US Food and Drug Administration approval of new drugs for patients with CRPC. However, despite the presence of new approved drugs such as enzalutamide, abiraterone, sipuleucel-T, cabazitaxel, and alpharadin, there is still an unmet need for novel agents with different mechanisms of action to target CRPC. Based on earlier studies demonstrating therapeutic potential of a quinoline-3-carboxamide agent roquinimex as an anticancer drug, efforts were directed to identify other useful members in this class. Tasquinimod is a second-generation quinoline-3-carboxamide agent that is currently in final stages of clinical development as a treatment for CRPC. The preclinical studies of tasquinimod have formed the basis for its success as an antiangiogenic and immunomodulatory agent in this disease. Tasquinimod is an orally available agent that has shown efficacy and favorable safety profile as deduced by the results of Phase I and II clinical trials of this drug in prostate cancer. The place of tasquinimod in the treatment of CRPC patients is currently under examination in an ongoing Phase III clinical trial. In this review, we will discuss tasquinimod, starting from its discovery and current knowledge on potential mechanisms of action to its clinical potential in CRPC.

The experimental autoimmune encephalomyelitis (EAE) model of MS: utility for understanding disease pathophysiology and treatment

While no single model can exactly recapitulate all aspects of multiple sclerosis (MS), animal models are essential in understanding the induction and pathogenesis of the disease and to develop therapeutic strategies that limit disease progression and eventually lead to effective treatments for the human disease. Several different models of MS exist, but by far the best understood and most commonly used is the rodent model of experimental autoimmune encephalomyelitis (EAE). This model is typically induced by either active immunization with myelin-derived proteins or peptides in adjuvant or by passive transfer of activated myelin-specific CD4+ T lymphocytes. Mouse models are most frequently used because of the inbred genotype of laboratory mice, their rapid breeding capacity, the ease of genetic manipulation, and availability of transgenic and knockout mice to facilitate mechanistic studies. Although not all therapeutic strategies for MS have been developed in EAE, all of the current US Food and Drug Administration (FDA)-approved immunomodulatory drugs are effective to some degree in treating EAE, a strong indicator that EAE is an extremely useful model to study potential treatments for MS. Several therapies, such as glatiramer acetate (GA: Copaxone), and natalizumab (Tysabri), were tested first in the mouse model of EAE and then went on to clinical trials. Here we discuss the usefulness of the EAE model in understanding basic disease pathophysiology and developing treatments for MS as well as the potential drawbacks of this model.

Calgranulins may contribute vascular protection in atherogenesis

S100A8, S100A9 and S100A12 are considered proinflammatory mediators of atherosclerosis. Known as calgranulins, they are major components of neutrophils and are upregulated in macrophages and foam cells. They influence leukocyte recruitment, and may propagate inflammation by binding TLR4 and/or receptor for advanced glycation endproducts (RAGE). However, the receptors for calgranulins remain an enigma; we have no evidence for TLR4 or RAGE activation by S100A8 or S100A12. Moreover, gene regulation studies suggest antiinflammatory functions for S100A8 and emerging reports indicate pleiotropic roles. Unlike S100A9, S100A8 effectively scavenges oxidants generated by the myeloperoxidase system in vivo, forming novel thiol modifications. S100A8 is also readily S-nitrosylated, stabilizing nitric oxide and transporting it to hemoglobin. S100A8-SNO reduces leukocyte transmigration in the vasculature. S-glutathionylation of S100A9 modifies its effects on leukocyte adhesion. Both S100A8 forms inhibit mast cell activation, at least partially by scavenging reactive oxygen species required for signaling. Conversely, S100A12 activates and sequesters mast cells. However S100A12 suppresses proinflammatory cytokine induction by SAA-activated monocytes and macrophages, and inhibits matrix metalloprotease activity. We propose that the abundance and types of cells expressing calgranulins in particular microenvironments, their relative concentrations and post-translational modifications may have distinct functional outcomes, including those that are protective, at different stages of atherogenesis.  

The quinoline-3-carboxamide paquinimod (ABR-215757) reduces leukocyte recruitment during sterile inflammation: leukocyte- and context-specific effects

Quinoline-3-carboxamides (Q-compounds) are currently in clinical development for both autoimmune disease and cancer. We have previously shown that the Q-compound paquinimod (ABR-215757) significantly ameliorates disease symptoms in several mouse models of human inflammatory disease. Considering that recruitment of inflammatory cells into tissue is a common denominator of these models, we have in this report investigated whether paquinimod would interfere with cell accumulation during sterile peritoneal inflammation. To mimic the cell recruitment elicited by tissue injury, we used necrotic cells to induce the acute inflammatory response. We show that per oral treatment with paquinimod significantly reduced the accumulation of Ly6C(hi) inflammatory monocytes and eosinophils, but not neutrophils, in this model, and that this correlated with reduced number of such cells also in the omentum. Treatment also reduced the accumulation of these cell populations at a subcutaneous site of inflammation. In alum-induced inflammation, however, neutrophils were the dominant cell population and paquinimod failed to reduce the accumulation of inflammatory cells. Taken together, our results indicate that paquinimod selectively inhibits cell recruitment during acute sterile inflammation, but that this effect is context-dependent. These data have important implications for the understanding of the mechanism of action of Q-compounds in both pre-clinical and clinical settings.

S100A8 and S100A9: DAMPs at the crossroads between innate immunity, traditional risk factors, and cardiovascular disease

Amplification of innate immune responses by endogenous danger-associated molecular patterns (DAMPs) promotes inflammation. The involvement of S100A8 and S100A9, DAMPs belonging to the S100 calgranulin family, in the pathogenesis of cardiovascular disease is attracting an increasing amount of interest. S100A8 and S100A9 (also termed MRP8 and MRP14) preferentially form the S100A8/A9 heterodimer (MRP8/14 or calprotectin) and are constitutively expressed in myeloid cells. The levels of circulating S100A8/A9 in humans strongly correlate to blood neutrophil counts and are increased by traditional cardiovascular risk factors such as smoking, obesity, hyperglycemia, and dyslipidemia. S100A8/A9 is an endogenous ligand of toll-like receptor 4 (TLR4) and of the receptor for advanced glycation end products (RAGE) and has been shown to promote atherogenesis in mice. In humans, S100A8/A9 correlates with the extent of coronary and carotid atherosclerosis and with a vulnerable plaque phenotype. S100A8/A9 is locally released following myocardial infarction and amplifies the inflammatory responses associated with myocardial ischemia/reperfusion injury. Elevated plasma levels of S100A8/A9 are associated with increased risk of future coronary events in healthy individuals and in myocardial infarction survivors. Thus, S100A8/A9 might represent a useful biomarker and therapeutic target in cardiovascular disease. Importantly, S100A8/A9 blockers have been developed and are approved for clinical testing.

Long-term survival and biomarker correlates of tasquinimod efficacy in a multicenter randomized study of men with minimally symptomatic metastatic castration-resistant prostate cancer

PURPOSE

Tasquinimod (Active Biotech) is an oral immunomodulatory, anti-angiogenic, and anti-metastatic agent that delayed metastatic disease progression in a randomized placebo-controlled phase II trial in men with metastatic castration-resistant prostate cancer (mCRPC). Here, we report long-term survival with biomarker correlates from this trial.

EXPERIMENTAL DESIGN

Two hundred and one (134 tasquinimod and 67 placebo) men with mCRPC were evaluated. Forty-one men randomized to placebo crossed over to tasquinimod. Survival data were collected with a median follow-up time of 37 months. Exploratory biomarker studies at baseline and over time were collected to evaluate potential mechanism-based correlates with tasquinimod efficacy including progression-free survival (PFS) and overall survival (OS).

RESULTS

With 111 mortality events, median OS was 33.4 months for tasquinimod versus 30.4 months for placebo overall, and 34.2 versus 27.1 months in men with bone metastases (n = 136), respectively. Multivariable analysis demonstrated an adjusted HR of 0.52 [95% confidence interval (CI), 0.35-0.78; P = 0.001] for PFS and 0.64 (95% CI, 0.42-0.97; P = 0.034) for OS, favoring tasquinimod. Time-to-symptomatic progression was improved with tasquinimod (P = 0.039, HR = 0.42). Toxicities tended to be mild in nature and improved over time. Biomarker analyses suggested a favorable impact on bone alkaline phosphatase and lactate dehydrogenase (LDH) over time and a transient induction of inflammatory biomarkers, VEGF-A, and thrombospondin-1 levels with tasquinimod. Baseline levels of thrombospondin-1 less than the median were predictive of treatment benefit.

CONCLUSIONS

The survival observed in this trial of men with minimally symptomatic mCRPC suggests that the prolongation in PFS with tasquinimod may lead to a survival advantage in this setting, particularly among men with skeletal metastases, and has a favorable risk:benefit ratio.

Mechanisms of action of tasquinimod on the tumour microenvironment

Tasquinimod is a small molecule with pleiotropic effects on the tumour microenvironment. Tasquinimod inhibits the growth and metastasis of tumour cells in vitro and in vivo. It targets the tumour microenvironment, enhancing the host immune response and inhibiting the angiogenic response. Tasquinimod influences infiltrating myeloid cells in the tumour milieu shifting the balance towards a less immunosuppressive phenotype. Myeloid-derived suppressor cells and tumour-associated macrophages are major components of the immunosuppressive microenvironment and as a result promote tumour growth and favour angiogenesis and metastasis formation. Growing evidence indicates that tasquinimod targets these myeloid cells and modulates local tumour immunity by blocking the interaction between the multifunctional protein S100A9 and its ligands receptor of advanced glycation end products and Toll-like receptor 4. Its anti-angiogenic effects are achieved at least in part through these effects on regulatory myeloid cells and also potentially through inactivating histone deacetylase-4 and reducing expression of hypoxia-inducible factor 1-controlled genes. The aim is to comprehensively review the mode of action of tasquinimod as a novel oral anti-cancer agent. Based on its unique combination of effects, tasquinimod is a novel agent with clinical therapeutic potential in various solid tumours, both alone and as part of rational combination therapy.

Management of patients with castration-resistant disease

The medical management of men with castration-resistant prostate cancer (CRPC) has changed dramatically in the last decade. Men can now access several agents developed to extend survival, delay morbidity caused by complications, and preserve quality of life. Strategies to extend survival include docetaxel and cabazitaxel, the CYP-inhibitor abiraterone acetate, the second-generation androgen receptor antagonist enzalutamide, sipuleucel-T immunotherapy, and the α-emitting radionuclide (223)radium. These novel therapies have fostered interest in translational science and a deeper understanding of the underlying biology of CRPC. This article summarizes clinical data and unresolved issues in the use of current and emerging CRPC therapies.

Functions of S100 proteins

The S100 protein family consists of 24 members functionally distributed into three main subgroups: those that only exert intracellular regulatory effects, those with intracellular and extracellular functions and those which mainly exert extracellular regulatory effects. S100 proteins are only expressed in vertebrates and show cell-specific expression patterns. In some instances, a particular S100 protein can be induced in pathological circumstances in a cell type that does not express it in normal physiological conditions. Within cells, S100 proteins are involved in aspects of regulation of proliferation, differentiation, apoptosis, Ca2+ homeostasis, energy metabolism, inflammation and migration/invasion through interactions with a variety of target proteins including enzymes, cytoskeletal subunits, receptors, transcription factors and nucleic acids. Some S100 proteins are secreted or released and regulate cell functions in an autocrine and paracrine manner via activation of surface receptors (e.g. the receptor for advanced glycation end-products and toll-like receptor 4), G-protein-coupled receptors, scavenger receptors, or heparan sulfate proteoglycans and N-glycans. Extracellular S100A4 and S100B also interact with epidermal growth factor and basic fibroblast growth factor, respectively, thereby enhancing the activity of the corresponding receptors. Thus, extracellular S100 proteins exert regulatory activities on monocytes/macrophages/microglia, neutrophils, lymphocytes, mast cells, articular chondrocytes, endothelial and vascular smooth muscle cells, neurons, astrocytes, Schwann cells, epithelial cells, myoblasts and cardiomyocytes, thereby participating in innate and adaptive immune responses, cell migration and chemotaxis, tissue development and repair, and leukocyte and tumor cell invasion.

Small molecules in the treatment of systemic lupus erythematosus

Advances in the understanding of the cellular biological events that underlie systemic lupus erythematosus (SLE) have led to the identification of key molecules and signaling pathways that are aberrantly expressed. The parallel development of small molecule drugs that inhibit or interfere with the specific perturbations identified, offers perspective for more rational, effective and less toxic therapy. In this review, we present data from preclinical and clinical studies of such emerging novel therapies with a particular focus on kinase inhibitors and other compounds that modulate signal transduction. Moreover, we highlight the use of chromatin-modifying medications, bringing attention to the central role of epigenetics in SLE pathogenesis.

Increased serum levels of S100A8/A9 and S100A12 are associated with cardiovascular disease in patients with inactive systemic lupus erythematosus

OBJECTIVES

Patients with SLE have an increased morbidity and mortality from cardiovascular disease (CVD). The reason for this is not entirely understood, but is believed to be partly related to the long-lasting inflammatory process seen in SLE. The aim of the present study was to investigate whether there is an association between CVD and serum levels of the proinflammatory proteins S100A8/A9 and S100A12 in SLE.

METHODS

Serum levels of S100A8/A9 and S100A12 were measured with ELISA in 237 SLE patients with clinically inactive disease and without infections, as well as in 100 healthy individuals. Cardiovascular manifestations were defined according to the SLICC/ACR Damage Index (SLICC/ACR-DI).

RESULTS

Serum levels of S100A8/A9 were elevated in our inactive SLE patients as compared with healthy individuals (P < 0.0001), which was not seen for S100A12 (P = 0.12). SLE patients with a history of CVD had increased serum levels of both S100A8/A9 and S100A12 compared with patients with no CVD or venous thromboembolism (P = 0.003 and P = 0.006, respectively). The presence of organ damage according to SLICC/ACR-DI was associated with an increase in both S100A8/A9 and S100A12 serum levels (P = 0.001 and P = 0.006, respectively).

CONCLUSION

Elevated serum levels of S100A8/A9 and S100A12 may be used as an indicator of severe disease and CVD in SLE, suggesting that SLE patients with elevated serum S100A8/A9 and S100A12 concentrations may benefit from more intense cardiovascular primary preventive strategies and possibly also from more intense and early immunosuppressive treatment.

From bevacizumab to tasquinimod: angiogenesis as a therapeutic target in prostate cancer

It was first posited in the 1970s that angiogenesis may prove to be a useful target for anticancer therapies. Since then, a number of agents have been developed and tested across a range of tumor types; however, to date, there have unfortunately been more failures than successes. Prostate cancer (PCa) is no exception in this regard, and despite a strong preclinical rationale for targeting angiogenesis in men with PCa, there has yet to be an antiangiogenic therapy proven to prolong survival in this group of patients. Drugs have been developed to target a host of angiogenesis mediators. These include vascular endothelial growth factor (VEGF), the VEGF receptors, antiangiogenic factors (e.g., thrombospondin-1), and downstream mediators of angiogenesis (e.g., hypoxia-inducible factor-1α and MET). At present, there are 2 drugs being tested in the phase III setting for men with PCa: cabozantinib and tasquinimod. Cabozantinib, a dual VEGF receptor-2/MET inhibitor, has shown dramatic beneficial effects on radiographically evident bone metastases and pain in the phase II setting. There are currently 2 large phase III trials underway to further investigate cabozantinib's role in treating men with PCa. Both trials randomize subjects to cabozantinib versus mitoxantrone: one is designed to evaluate overall survival, and the other, pain response durability. The other drug, tasquinimod, has a somewhat poorly understood mechanism of action. It is thought to exert an antiangiogenic effect through the inhibition of myeloid-derived suppressor cells, key to the support of an angiogenic environment, and down-regulation of hypoxia-inducible factor-1α. A phase II trial randomizing men to tasquinimod versus placebo revealed a median progression-free survival advantage in the experimental arm (7.6 vs. 3.3 months with placebo; P = 0.0042). Based on these encouraging phase II results, a randomized, double-blind, placebo-controlled trial in men with metastatic castration-resistant PCa was launched. That trial is powered for a primary endpoint of progression-free survival and is expected to enroll 1200 men.

Immunotherapy and immune evasion in prostate cancer

Metastatic prostate cancer remains to this day a terminal disease. Prostatectomy and radiotherapy are effective for organ-confined diseases, but treatment for locally advanced and metastatic cancer remains challenging. Although advanced prostate cancers treated with androgen deprivation therapy achieves debulking of disease, responses are transient with subsequent development of castration-resistant and metastatic disease. Since prostate cancer is typically a slowly progressing disease, use of immune-based therapies offers an advantage to target advanced tumors and to induce antitumor immunity. This review will discuss the clinical merits of various vaccines and immunotherapies in castrate resistant prostate cancer and challenges to this evolving field of immune-based therapies.

Common interactions between S100A4 and S100A9 defined by a novel chemical probe

S100A4 and S100A9 proteins have been described as playing roles in the control of tumor growth and metastasis. We show here that a chemical probe, oxyclozanide (OX), selected for inhibiting the interaction between S100A9 and the receptor for advanced glycation end-products (RAGE) interacts with both S100A9 and S100A4. Furthermore, we show that S100A9 and S100A4 interact with RAGE and TLR4; interactions that can be inhibited by OX. Hence, S100A4 and S100A9 display similar functional elements despite their primary sequence diversity. This was further confirmed by showing that S100A4 and S100A9 dimerize both in vitro and in vivo. All of these interactions required levels of Zn⁺⁺ that are found in the extracellular space but not intracellularly. Interestingly, S100A4 and S100A9 are expressed by distinct CD11b⁺ subpopulations both in healthy animals and in animals with either inflammatory disease or tumor burden. The functions of S100A9 and S100A4 described in this paper, including heterodimerization, may therefore reflect S100A9 and S100A4 that are released into the extra-cellular milieu.

Beneficial effects of quinoline-3-carboxamide (ABR-215757) on atherosclerotic plaque morphology in S100A12 transgenic ApoE null mice

OBJECTIVE

There is an emerging widespread interest in the role of damage-associated molecular pattern molecules (DAMP) S100A8, S100A9 and S100A12 in cardiovascular and other diseases. In this study we tested the efficacy of ABR-215757, a S100 protein binding immuno-modulatory compound to stabilize atherosclerosis in transgenic ApoE null mice that express the human pro-inflammatory S100A12 protein within the smooth muscle cell (SM22α-S100A12).

METHODS

Twelve-week old S100A12 transgenic/ApoE(-/-) and WT/ApoE(-/-) mice were treated with ABR-21575 for 5 weeks and were analyzed 4 month later.

RESULTS

Surface plasmon resonance analysis demonstrated that S100A12 interacts with ABR-215757 in a zinc dependent manner in vitro. In vivo, ABR-215757 administration reduced features of advanced plaque morphology resulting in smaller necrotic cores, diminished intimal and medial vascular calcification, and reduced amount of infiltrating inflammatory cells. ABR-215757 normalized aortic expression of RAGE protein and normalized experimentally-induced delayed hypersensitivity. The effect of ABR-215757 was more prominent in ApoE(-/-) mice expressing S100A12 than in ApoE(-/-) animals lacking expression of human S100A12 protein.

CONCLUSION

Our data suggest that S100A12 is important for progression of atherosclerosis and can be targeted by the small molecule ABR-215757. The specific binding of quinoline-3-carboxamides to S100A12 attenuates S100A12-mediated features of accelerated murine atherosclerosis.

S100A12 suppresses pro-inflammatory, but not pro-thrombotic functions of serum amyloid A

S100A12 is elevated in the circulation in patients with chronic inflammatory diseases and recent studies indicate pleiotropic functions. Serum amyloid A induces monocyte cytokines and tissue factor. S100A12 did not stimulate IL-6, IL-8, IL-1β or TNF-α production by human peripheral blood mononuclear cells but low amounts consistently reduced cytokine mRNA and protein levels induced by serum amyloid A, by ∼49% and ∼46%, respectively. However, S100A12 did not affect serum amyloid A-induced monocyte tissue factor. In marked contrast, LPS-induced cytokines or tissue factor were not suppressed by S100A12. S100A12 did not alter cytokine mRNA stability or the cytokine secretory pathway. S100A12 and serum amyloid A did not appear to form complexes and although they may have common receptors, suppression was unlikely via receptor competition. Serum amyloid A induces cytokines via activation of NF-κB and the MAPK pathways. S100A12 reduced serum amyloid A-, but not LPS-induced ERK1/2 phosphorylation to baseline. It did not affect JNK or p38 phosphorylation or the NF-κB pathway. Reduction in ERK1/2 phosphorylation by S100A12 was unlikely due to changes in intracellular reactive oxygen species, Ca²⁺ flux or to recruitment of phosphatases. We suggest that S100A12 may modulate sterile inflammation by blunting pro-inflammatory properties of lipid-poor serum amyloid A deposited in chronic lesions where both proteins are elevated as a consequence of macrophage activation.

Human S100A9 protein is stabilized by inflammatory stimuli via the formation of proteolytically-resistant homodimers

S100A8 and S100A9 are Ca(2+)-binding proteins that are associated with acute and chronic inflammation and cancer. They form predominantly heterodimers even if there are data supporting homodimer formation. We investigated the stability of the heterodimer in myeloid and S100A8/S100A9 over-expressing COS cells. In both cases, S100A8 and S100A9 proteins were not completely degraded even 48 hrs after blocking protein synthesis. In contrast, in single transfected cells, S100A8 protein was completely degraded after 24 h, while S100A9 was completely unstable. However, S100A9 protein expression was rescued upon S100A8 co-expression or inhibition of proteasomal activity. Furthermore, S100A9, but not S100A8, could be stabilized by LPS, IL-1β and TNFα treatment. Interestingly, stimulation of S100A9-transfected COS cells with proteasomal inhibitor or IL-1β lead to the formation of protease resistant S100A9 homodimers. In summary, our data indicated that S100A9 protein is extremely unstable but can be rescued upon co-expression with S100A8 protein or inflammatory stimuli, via proteolytically resistant homodimer formation. The formation of S100A9 homodimers by this mechanism may constitute an amplification step during an inflammatory reaction.

A review of tasquinimod in the treatment of advanced prostate cancer

Castration resistant prostate cancer remains a major clinical burden and novel therapeutic options are urgently required to improve survival. Tasquinimod is an orally administered quinoline-3-carboxamide with potent antiangiogenic and antitumorigenic action that has shown promise in the treatment of advanced prostate cancers. This review explores both preclinical and clinical findings to date. In summary, tasquinimod has been shown to demonstrate a potent in vitro and in vivo anticancer action and completed early phase clinical trials have demonstrated good drug tolerance and prolonged progression-free survival. Although Phase III clinical trials are on-going, the findings to date highlight the promise of this drug in the treatment of advanced prostate cancer.

Amelioration of experimental autoimmune encephalomyelitis by the quinoline-3-carboxamide paquinimod: reduced priming of proinflammatory effector CD4(+) T cells

Quinoline-3-carboxamide compounds (Q compounds) have demonstrated efficacy in treating autoimmune disease in both humans and mice. However, the mode of action of these compounds is poorly understood. Here, we show that preventive treatment with the Q compound paquinimod (ABR-215757) during the first 5 days after induction of experimental autoimmune encephalomyelitis is sufficient to significantly ameliorate disease symptoms. Parallel cell-depletion experiments demonstrated that Ly6C(hi) inflammatory monocytes play an essential role in this phase. The paquinimod-induced amelioration correlated with reduced priming of antigen-specific CD4(+) T cells and reduced frequency of IFN-γ- and IL-17-producing cells in draining lymph nodes. Importantly, the treatment did not inhibit T-cell division per se. In mice with established experimental autoimmune encephalomyelitis, the numbers of Ly6C(hi) CD115(+) inflammatory monocytes and CD11b(+)CD11c(+) dendritic cells (DCs) were reduced in spleen, but not in bone marrow or draining lymph nodes of treated mice. Inflammatory monocyte-derived DCs and CD4(+) T cells were also reduced in the brain. In contrast, there was no decrease in DC subsets previously shown to be critical for effector CD4(+) T-cell development in lymph nodes. Taken together, these data indicate that preventive treatment with paquinimod ameliorates experimental autoimmune encephalomyelitis by reducing effector T-cell priming and, on prolonged treatment, displays a selective effect by decreasing distinct subpopulations of splenic CD11b(+) myeloid cells.

CD11b+Ly6C++Ly6G- cells show distinct function in mice with chronic inflammation or tumor burden

Background

S100A9 has been shown to be important for the function of so called Myeloid Derived Suppressor Cells (MDSC). Cells with a similar phenotype are also involved in pro-inflammatory processes, and we therefore wanted to investigate the gene expression and function of these cells in animals that were either subjected to chronic inflammation, or inoculated with tumors.

Methods

CD11b⁺Ly6C⁺⁺ and Ly6G⁺ cells were isolated from spleen, tumor tissue or inflammatory granulomas. S100A9, Arginase 1 and iNOS gene expression in the various CD11b⁺ cell populations was analyzed using Q-PCR. The suppressive activity of the CD11b⁺ cell populations from different donors was studied in co-culture experiments.

Results

S100A9 was shown to be expressed mainly in splenic CD11b⁺Ly6C⁺G⁺ cells both at the RNA and protein level. Arginase I and iNOS expression could be detected in both CD11b⁺Ly6C⁺Ly6G⁺ and CD11b⁺Ly6C⁺G^-/C⁺⁺G^- derived from tumors or a site of chronic inflammation, but was very low in the same cell populations isolated from the spleen. CD11b⁺ cells isolated from mice with peritoneal chronic inflammation were able to stimulate T lymphocytes, while CD11b⁺ cells from mice with peritoneal tumors suppressed T cell growth.

Conclusion

An identical CD11b⁺Ly6C⁺⁺G^- cell population appears to have the ability to adopt immune stimulatory or immune suppressive functions dependent on the presence of a local inflammatory or tumor microenvironment. Thus, there is a functional plasticity in the CD11b⁺Ly6C⁺⁺G^- cell population that cannot be distinguished with the current molecular markers.

Phagocyte-derived S100 proteins in autoinflammation: putative role in pathogenesis and usefulness as biomarkers

The cytoplasmic S100 proteins derived from cells of myeloid origin are promising new markers of (auto-)inflammation. S100A8/A9 and S100A12 are released from monocytes and granulocytes during activation of the innate immune system. Tissue and serum concentrations correlate to disease activity, both during local and systemic inflammation. In autoinflammatory diseases such as Familial Mediterranean Fever (FMF) and Systemic onset Juvenile Idiopathic Arthritis (SJIA), a dysregulation of alternative secretory pathways may be involved in pathogenesis and lead to hypersecretion of S100 proteins. Since autoinflammatory diseases can be difficult to diagnose, phagocyte-derived S100 proteins are valid tools in the diagnosis of autoinflammatory diseases. In addition, they may help achieve a better understanding of the pathophysiology of autoinflammatory disorders including SJIA and FMF, and even provide novel therapeutic targets in the future.

The alarmin Mrp8/14 as regulator of the adaptive immune response during allergic contact dermatitis

Mrp8 and Mrp14 are endogenous alarmins amplifying inflammation via Toll-like receptor-4 (TLR-4) activation. Due to their pro-inflammatory properties, alarmins are supposed to enhance adaptive immunity via activation of dendritic cells (DCs). In contrast, analysing a model of allergic contact dermatitis (ACD) we observed a more severe disease outcome in Mrp8/14-deficient compared to wild-type mice. This unexpected phenotype was associated with an enhanced T-cell response due to an accelerated maturation of DCs in Mrp8/14-deficient mice. Accordingly, Mrp8, the active component of the heterocomplex, inhibits early DC maturation and antigen presentation in a TLR-4-dependent manner. Transfer of DCs purified from the local lymph nodes of sensitized Mrp8/14-deficient to wild-type mice determined the outcome of ACD. Our results link a pro-inflammatory role of the endogenous TLR-4 ligand Mrp8/14 to a regulatory function in adaptive immunity, which shows some similarities with the 'hygiene hypothesis' regarding continuous TLR-4 stimulation and decreased risk of allergy.

Tasquinimod Is an Allosteric Modulator of HDAC4 survival signaling within the compromised cancer microenvironment

Tasquinimod is an orally active antiangiogenic drug that is currently in phase III clinical trials for the treatment of castration-resistant prostate cancer. However, the target of this drug has remained unclear. In this study, we applied diverse strategies to identify the histone deacetylase HDAC4 as a target for the antiangiogenic activity of tasquinimod. Our comprehensive analysis revealed allosteric binding (Kd 10-30 nmol/L) to the regulatory Zn(2+) binding domain of HDAC4 that locks the protein in a conformation preventing HDAC4/N-CoR/HDAC3 complex formation. This binding inhibited colocalization of N-CoR/HDAC3, thereby inhibiting deacetylation of histones and HDAC4 client transcription factors, such as HIF-1α, which are bound at promoter/enhancers where epigenetic reprogramming is required for cancer cell survival and angiogenic response. Through this mechanism, tasquinimod is effective as a monotherapeutic agent against human prostate, breast, bladder, and colon tumor xenografts, where its efficacy could be further enhanced in combination with a targeted thapsigargin prodrug (G202) that selectively kills tumor endothelial cells. Together, our findings define a mechanism of action of tasquinimod and offer a perspective on how its clinical activity might be leveraged in combination with other drugs that target the tumor microenvironment. Cancer Res; 73(4); 1386-99. ©2012 AACR.

Induction of nuclear factor-κB responses by the S100A9 protein is Toll-like receptor-4-dependent

Interactions between danger-associated molecular patterns (DAMP) and pathogen-associated molecular patterns (PAMP) and pattern recognition receptors such as Toll-like receptors (TLRs) are critical for the regulation of the inflammatory process via activation of nuclear factor-κB (NF-κB) and cytokine secretion. In this report, we investigated the capacity of lipopolysaccharide (LPS) -free S100A9 (DAMP) protein to activate human and mouse cells compared with lipoprotein-free LPS (PAMP). First, we showed that LPS and S100A9 were able to increase NF-κB activity followed by increased cytokine and nitric oxide (NO) secretion both in human THP-1 cells and in mouse bone marrow-derived dendritic cells. Surprisingly, although S100A9 triggered a weaker cytokine response than LPS, we found that S100A9 more potently induced IκBα degradation and hence NF-κB activation. Both the S100A9-induced response and the LPS-induced response were completely absent in TLR4 knockout mice, whereas it was only slightly affected in RAGE knockout mice. Also, we showed that LPS and S100A9 NF-κB induction were strongly reduced in the presence of specific inhibitors of TLR-signalling. Chloroquine reduced S100A9 but not LPS signalling, indicating that S100A9 may need to be internalized to be fully active as a TLR4 inducer. This was confirmed using A488-labelled S100A9 that was internalized in THP-1 cells, showing a raise in fluorescence after 30 min at 37°. Chloroquine treatment significantly reduced the fluorescence. In summary, our data indicate that both human and mouse S100A9 are TLR4 agonists. Importantly, S100A9 induced stronger NF-κB activation albeit weaker cytokine secretion than LPS, suggesting that S100A9 and LPS activated NF-κB in a qualitatively distinct manner.

Review of S100A9 biology and its role in cancer

S100A9 is a calcium binding protein with multiple ligands and post-translation modifications that is involved in inflammatory events and the initial development of the cancer cell through to the development of metastatic disease. This review has a threefold purpose: 1) describe the S100A9 structural elements important for its biological activity, 2) describe the S100A9 biology in the context of the immune system, and 3) illustrate the role of S100A9 in the development of malignancy via interactions with the immune system and other cellular processes.

Pharmacokinetics, tolerability, and preliminary efficacy of paquinimod (ABR-215757), a new quinoline-3-carboxamide derivative: studies in lupus-prone mice and a multicenter, randomized, double-blind, placebo-controlled, repeat-dose, dose-ranging study in patients with systemic lupus erythematosus

OBJECTIVE

To assess the efficacy of paquinimod, a new immunomodulatory small molecule, in a murine lupus model, and to evaluate its pharmacokinetics and tolerability in systemic lupus erythematosus (SLE) patients at doses predicted to be efficacious and safe and determine the maximum tolerated dose.

METHODS

The efficacy of paquinimod was studied in lupus-prone MRL-lpr/lpr mice and compared with that of established SLE treatments. Dose-response data and pharmacokinetic data were used to calculate effective and safe clinical doses of paquinimod. The pharmacokinetics and tolerability of paquinimod were evaluated in a phase Ib double-blind, placebo controlled, dose-ranging study in which cohorts of SLE patients received daily oral treatment for 12 weeks.

RESULTS

Paquinimod treatment resulted in disease inhibition in MRL-lpr/lpr mice, comparable to that obtained with prednisolone and mycophenolate mofetil; prominent effects on disease manifestations and serologic markers and a steroid-sparing effect were observed. In patients with SLE, the pharmacokinetic properties of paquinimod were linear and well suitable for once-daily oral treatment. The majority of the adverse events (AEs) were mild or moderate, and transient. The most frequent AEs were arthralgia and myalgia, reported with the highest dose levels of paquinimod (4.5 mg/day and 6.0 mg/day). At the 4.5 mg/day dose level and higher, some AEs of severe intensity and serious adverse events were reported.

CONCLUSION

Paquinimod effectively inhibited disease and had a steroid-sparing effect in experimental lupus. Results from preclinical models together with pharmacokinetic data were successfully translated into a safe clinical dose range, and doses of up to 3.0 mg/day were well tolerated in the SLE patients. Taken together, the promising combined data from a murine model and human SLE support the future clinical development of paquinimod.

Inhibition of metastasis in a castration resistant prostate cancer model by the quinoline-3-carboxamide tasquinimod (ABR-215050)

BACKGROUND

Tasquinimod (ABR-215050) is an orally active quinoline-3-carboxamide analog that has completed phase II clinical trial in patients with castration resistant prostate cancer, showing promising inhibiting effects on the occurrence of metastasis and delayed disease progression. Its mechanism of action is not fully elucidated, but previous studies show anti-angiogenic effects and strong interaction with the S100A9 protein.

METHODS

This study was performed to evaluate if tasquinimod inhibits prostate cancer metastasis, by using both orthotopic and intratibial xenograft models. Animals were treated with tasquinimod, and tumor growth characteristics as well as molecular markers for metastasis and angiogenesis were analyzed.

RESULTS

The results show that formation of lung and lymph node metastases from orthotopic castration resistant prostate tumors was inhibited by tasquinimod treatment. Importantly, establishment of tumors in the bone after intratibial implantation was suppressed by tasquinimod. In addition, establishment and growth of subcutaneous tumors were affected. Both in primary tumors and serum from treated mice an upregulation of thrombospondin 1 was observed. Further, downregulation of the hypoxia driven genes VEGF, CXCR4, and LOX was detected in the primary tasquinimod-treated tumors and decreased expression of chemotactic ligand SDF-1 was demonstrated in the lungs. Thus, these molecular changes could contribute to the anti-angiogenic and anti-metastatic effects of tasquinimod.

CONCLUSIONS

In conclusion, this study and clinical data show that tasquinimod interferes with the metastatic process, presumably by inhibition of tumor establishment. Therefore, tasquinimod is an interesting treatment option for patients with prostate cancer prone to metastasis.

Emerging targeted therapies for castration-resistant prostate cancer

Until recently, few therapeutic options were available for patients with castration-resistant prostate cancer (CRPC). Since 2010, four new molecules with a demonstrated benefit (sipuleucel-T, cabazitaxel, abiraterone, and denosumab) have been approved in this setting, and to-date several other agents are under investigation in clinical trials. The purpose of this review is to present an update of targeted therapies for CRPC. Presented data are obtained from literature and congress reports updated until December 2011. Targeted therapies in advanced phases of clinical development include novel androgen signaling inhibitors, inhibitors of alternative signaling pathways, anti-angiogenic agents, inhibitors that target the bone microenvironment, and immunotherapeutic agents. Radium-223 and MDV3100 demonstrated a survival advantage in phase III trials and the road for their introduction in clinical practice is rapidly ongoing. Results are also awaited for phase III studies currently underway or planned with new drugs given as monotherapy (TAK-700, cabozantinib, tasquinimod, PROSTVAC-VF, ipilimumab) or in combination with docetaxel (custirsen, aflibercept, dasatinib, zibotentan). The optimal timing, combination, and sequencing of emerging therapies remain unknown and require further investigation. Additionally, the identification of novel markers of response and resistance to these therapies may better individualize treatment for patients with CRPC.

Targeting angiogenesis for the treatment of prostate cancer

INTRODUCTION

While multiple therapies exist that prolong the lives of men with advanced prostate cancer, none are curative. This had led to a search to uncover novel targets for prostate cancer therapy, distinct from those of traditional hormonal approaches, chemotherapies, immunotherapies and bone-targeting approaches. The process of tumor angiogenesis is one target that is being exploited for therapeutic gain.

AREAS COVERED

The most promising anti-angiogenic approaches for treatment of prostate cancer, focusing on clinical development of selected agents. These include VEGF-directed therapies, tyrosine kinase inhibitors, tumor-vascular disrupting agents, immunomodulatory drugs and miscellaneous anti-angiogenic agents. While none of these drugs have yet entered the market for the treatment of prostate cancer, several are now being tested in Phase III registrational trials.

EXPERT OPINION

The development of anti-angiogenic agents for prostate cancer has met with several challenges. This includes discordance between traditional prostate-specific antigen responses and clinical responses, which have clouded clinical trial design and interpretation, potential inadequate exposure to anti-angiogenic therapies with premature discontinuation of study drugs and the development of resistance to anti-angiogenic monotherapies. These barriers will hopefully be overcome with the advent of more potent agents, the use of dual angiogenesis inhibition and the design of more informative clinical trials.

Laquinimod, a quinoline-3-carboxamide, induces type II myeloid cells that modulate central nervous system autoimmunity

Laquinimod is a novel oral drug that is currently being evaluated for the treatment of relapsing-remitting (RR) multiple sclerosis (MS). Using the animal model for multiple sclerosis, experimental autoimmune encephalomyelitis (EAE), we examined how laquinimod promotes immune modulation. Oral laquinimod treatment reversed established RR-EAE and was associated with reduced central nervous system (CNS) inflammation, decreased Th1 and Th17 responses, and an increase in regulatory T cells (Treg). In vivo laquinimod treatment inhibited donor myelin-specific T cells from transferring EAE to naive recipient mice. In vivo laquinimod treatment altered subpopulations of myeloid antigen presenting cells (APC) that included a decrease in CD11c⁺CD11b⁺CD4⁺ dendritic cells (DC) and an elevation of CD11b^hiGr1^hi monocytes. CD11b⁺ cells from these mice exhibited an anti-inflammatory type II phenotype characterized by reduced STAT1 phosphorylation, decreased production of IL-6, IL-12/23 and TNF, and increased IL-10. In adoptive transfer, donor type II monocytes from laquinimod-treated mice suppressed clinical and histologic disease in recipients with established EAE. As effects were observed in both APC and T cell compartments, we examined whether T cell immune modulation occurred as a direct effect of laquinimod on T cells, or as a consequence of altered APC function. Inhibition of Th1 and Th17 differentiation was observed only when type II monocytes or DC from laquinimod-treated mice were used as APC, regardless of whether myelin-specific T cells were obtained from laquinimod-treated or untreated mice. Thus, laquinimod modulates adaptive T cell immune responses via its effects on cells of the innate immune system, and may not influence T cells directly.

S100A9 interaction with TLR4 promotes tumor growth

By breeding TRAMP mice with S100A9 knock-out (S100A9^−/−) animals and scoring the appearance of palpable tumors we observed a delayed tumor growth in animals devoid of S100A9 expression. CD11b⁺ S100A9 expressing cells were not observed in normal prostate tissue from control C57BL/6 mice but were readily detected in TRAMP prostate tumors. Also, S100A9 expression was observed in association with CD68⁺ macrophages in biopsies from human prostate tumors. Delayed growth of TRAMP tumors was also observed in mice lacking the S100A9 ligand TLR4. In the EL-4 lymphoma model tumor growth inhibition was observed in S100A9^−/− and TLR4^−/−, but not in RAGE^−/− animals lacking an alternative S100A9 receptor. When expression of immune-regulating genes was analyzed using RT-PCR the only common change observed in mice lacking S100A9 and TLR4 was a down-regulation of TGFβ expression in splenic CD11b⁺ cells. Lastly, treatment of mice with a small molecule (ABR-215050) that inhibits S100A9 binding to TLR4 inhibited EL4 tumor growth. Thus, S100A9 and TLR4 appear to be involved in promoting tumor growth in two different tumor models and pharmacological inhibition of S100A9-TLR4 interactions is a novel and promising target for anti-tumor therapies.

Pro-inflammatory S100A8 and S100A9 proteins: self-assembly into multifunctional native and amyloid complexes

S100A8 and S100A9 are EF-hand Ca²⁺ binding proteins belonging to the S100 family. They are abundant in cytosol of phagocytes and play critical roles in numerous cellular processes such as motility and danger signaling by interacting and modulating the activity of target proteins. S100A8 and S100A9 expression levels increased in many types of cancer, neurodegenerative disorders, inflammatory and autoimmune diseases and they are implicated in the numerous disease pathologies. The Ca²⁺ and Zn²⁺-binding properties of S100A8/A9 have a pivotal influence on their conformation and oligomerization state, including self-assembly into homo- and heterodimers, tetramers and larger oligomers. Here we review how the unique chemical and conformational properties of individual proteins and their structural plasticity at the quaternary level account for S100A8/A9 functional diversity. Additional functional diversification occurs via non-covalent assembly into oligomeric and fibrillar amyloid complexes discovered in the aging prostate and reproduced in vitro. This process is also regulated by Ca²⁺and Zn²⁺-binding and effectively competes with the formation of the native complexes. High intrinsic amyloid-forming capacity of S100A8/A9 proteins may lead to their amyloid depositions in numerous ailments characterized by their elevated expression patterns and have additional pathological significance requiring further thorough investigation.

Phase II randomized, double-blind, placebo-controlled study of tasquinimod in men with minimally symptomatic metastatic castrate-resistant prostate cancer

PURPOSE

The activity of the novel antitumor agent tasquinimod (TASQ) with S100A9 as a molecular target was investigated in men with metastatic castration-resistant prostate cancer (CRPC) and minimal symptoms.

PATIENTS AND METHODS

We conducted a randomized, double-blind, placebo-controlled phase II trial in men assigned (at a ratio of two to one) to either oral once-daily TASQ 0.25 mg/d escalating to 1.0 mg/d over 4 weeks or placebo. The primary end point was the proportion of patients without disease progression at 6 months, defined by Response Evaluation Criteria in Solid Tumors Group, Prostate Cancer Working Group (PCWG2), or pain criteria, excluding prostate-specific antigen.

RESULTS

Two hundred one men (134 assigned to TASQ; 67 to placebo) were evaluable, and baseline characteristics were well balanced. Six-month progression-free proportions for TASQ and placebo groups were 69% and 37%, respectively (P < .001), and median progression-free survival (PFS) was 7.6 versus 3.3 months (P = .0042). In PCWG2 CRPC clinical subgroups, PFS in months was as follows: nodal metastases, 6.1 versus 3.1; bone metastases, 8.8 versus 3.4; and visceral metastases, 6.0 versus 3.0 for patients receiving TASQ versus placebo, respectively. Bone alkaline phosphatase levels were stabilized in the TASQ group, whereas the impact on PSA kinetics was less pronounced. Adverse events (AEs) occurring more frequently in the TASQ arm included GI disorders, fatigue, musculoskeletal pains, and elevations of pancreatic and inflammatory biomarkers. Grade 3 to 4 AEs, including asymptomatic elevations of laboratory parameters, were reported in 40% of patients receiving TASQ versus 10% receiving placebo; deep vein thrombosis (4% v 0%) was more common in the TASQ arm.

CONCLUSION

TASQ significantly slowed progression and improved PFS in patients with metastatic CRPC with an acceptable AE profile.

Emerging therapeutic approaches in the management of metastatic castration-resistant prostate cancer

Although treatment options for men with castration-resistant prostate cancer (CRPC) have improved with the recent and anticipated approvals of novel immunotherapeutic, hormonal, chemotherapeutic and bone-targeted agents, clinical benefit with these systemic therapies is transient and survival times remain unacceptably short. Thus, we devote the second section of this two-part review to discussing emerging therapeutic paradigms and research strategies that are entering phase II and III clinical testing for men with metastatic CRPC. We will discuss a range of emerging hormonal, immunomodulatory, antiangiogenic, epigenetic and cell survival pathway inhibitors in current clinical trials, with an emphasis on how these therapies may complement our existing treatment options.