Current Pharmaceutical Design - Volume 21, Issue 17, 2015

The advent of biologic therapy has transformed the outcomes of patients with Rheumatoid Arthritis (RA), but has also highlighted important issues for their development. Early attempts at T-cell driven therapies gave mixed results with difficulties extrapolating from non-human models to first in man trials. There is currently one T-cell modulating therapy – abatacept – licenced for use in RA. Cytokine inhibition has proven to be more fruitful with a number of anti-TNF and IL6 agents either licenced for use in RA or in development. The B-cell depleting therapy rituximab has also shown good efficacy as a chemotherapy agent repurposed for RA treatment. Overall the biologics show good efficacy in RA and have been shown to retard progression of radiographic joint damage. However, this benefit comes with a burden of increased infection risk and a financial cost significantly higher than conventional disease modifying therapies. As a result current UK licencing holds the biologics in reserve following failure of a conventional therapy and the presence of moderate to severely active disease. The long term use of the biologics in RA has highlighted the risk of immunogenicity, with significant proportions of patients developing anti-drug antibodies and losing therapeutic effect. The side effect profile and cost also raise the question around duration of therapy and trials of drug tapering following disease remission are now taking place with several biologic agents. Our inability to stratify patients to the most appropriate biologic drug (stratified or precision medicine) has also catalysed a large and critically important research agenda. Beyond identifying new biologic targets, the development of biosimilar agents will likely drive the future shape of the RA biologics market as lower cost alternatives are developed, thereby improving access to these therapies.

Monoclonal antibodies have undergone a radical evolutionary journey over the last 25 years, with advances in molecular biology, process development and drug formulation underpinning their rise to becoming one of the most efficacious and economically important class of drug today. The success of antibodies for the treatment of rheumatological conditions, such as rheumatoid arthritis in particular, has driven the biopharmaceutical industry to optimize all aspects of therapeutic antibody discovery and development, in order to provide further benefits for patients over and above marketed treatments, via increased clinical efficacy and patient convenience. Recent advances in many of the key aspects of antibody design that are driving this evolution, such as affinity optimization, effector function modulation, pharmacokinetic engineering, as well as developments in subcutaneous drug delivery, are reviewed here.

Rheumatoid arthritis (RA) is a common and debilitating disease. Expanded therapeutic options, targeting pro-inflammatory cytokines such as tumour necrosis factor (TNF) and interleukin-6 (IL-6), have revolutionised RA treatment. To date, efficacy data shows superiority of IL-6 inhibition over placebo, conventional disease modifying anti-rheumatic drugs such as methotrexate, and TNF inhibition. Moreover, while demonstrating some key differences in the safety profile compared with TNF inhibition (e.g. hyperlipidemia and neutropenia), these safety concerns have not, at least to date, been found to cause clinically significant adverse outcomes. Other safety parameters, such as infection and malignancy rates have been found to be comparable between IL-6 and TNF inhibition. This review explores the biology and clinical applications of IL-6 inhibition in the management of RA.

Interleukin-1 inhibitors were tested in large arthritis trials with less than impressive results, despite having convincing disease expression data and pre-clinical animal model supporting the potential pathogenic role of this cytokine in these settings. Despite disappointing beginnings, some IL-1 pathway blocking drugs are now beginning to find a place in the pharmacopoeia of rheumatologists. Drug developers utilised rapidly growing understanding of the molecular pathway and the genetic basis of key diseases to seek out conditions in which IL-1 pathway activation was much more likely to have a pivotal role in disease pathogenesis compared to the major arthritides. This review details the crucial advances in understanding of the IL-1 pathway activation which enabled this progress, particularly the advent of inflammasome biology. The drug development of IL-1 biologics in rheumatological diseases makes a fascinating case study illustrating major changes in drug development strategy encompassing closer synergies between translational biology, underlying molecular pathophysiology of disease, and novel clinical development pathways of biologic therapeutics.

Given the paucity of effective therapies and the increasing prevalence of osteoarthritis (OA) with ageing and overweight populations, new therapies for this painful, life-impairing condition are desperately needed, for both symptom relief and structural modification. With a growing understanding that OA involves multiple tissue pathologies including inflammation, many more therapeutic targets have been identified. This review will provide a current overview on the role of biologics in OA, including anti-tumour necrosis factor agents, growth factors and interleukin-1 antagonists.

Rheumatoid Arthritis (RA) is a chronic, inflammatory, autoimmune disease affecting diarthrodial joints and extra-articular tissues; in the absence of an effective treatment, it is characterized by persistent symmetrical and erosive synovitis which leads to structural joint damage and lifelong disability. Several autoantibodies have been associated with RA such as rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA). B cells have been shown to play a crucial role in the pathogenesis of RA by producing autoantibodies and promoting synovial inflammation through antigen presentation, T cells activation and cytokines production [1]. Although biologic agents have notably improved disease outcome and patients’ quality of life, currently around 30-40% of subjects do not respond to treatment and the mechanisms leading to resistance are still not known [2]. For this reason, new prognostic biomarkers and predictors of response are needed. We and others have postulated that the development of biomarkers for patients’ stratification prior therapeutic intervention may be possible through a better understanding of the different histopathological patterns present both in early and established individual RA patient and the related underlying cellular and molecular mechanisms. To date, Tumor Necrosis Factor (TNF)-α has been shown to be one of the master elements of inflammation in RA; however, even though therapies aimed at blocking this key cytokine have emerged as a major tool in the treatment of RA, a large proportion of patients (approximately 30-40%) do not achieve a meaningful clinical response assessed by either the American College of Rheumatology (ACR) or the European League Against Rheumatism (EULAR) criteria. The same limitation can be applied to the use of rituximab, a chimeric monoclonal antibody directed against CD20, which is uniquely expressed by all B-lymphocytes during the maturation process from late stage pro-B cells to memory cells. The clinical efficacy of rituximab has been proved by several clinical studies [3] but it is highly variable. Currently, NICE guidelines recommend rituximab in patients with inadequate response to a first-line biologic therapy, including at least one anti-TNFα agent independently of their pre-treatment chance to respond. In all cases, whether considering biologics used for several years in RA patients (anti-TNFα or rituximab) or relatively newer biologics in clinical use (i.e. tocilizumab, an anti-interleukin (IL) -6 receptor blocking monoclonal antibody or abatacept, a CTLA4 inhibitor fusion protein designed to target the T cell co-stimulatory signal mediated through the CD28-CD80/86 pathway), no validated biomarkers predictive of clinical response currently exist. Consequently, to date a “trial-and-error” approach is used in the prescription of biologics in RA, which has the obvious disadvantage of potentially exposing patients to drugs that they may not respond, with potential unnecessary side-effects, delaying use of an effective treatment and causing a significant economic burden to society. Therefore, identifying pre-treatment predictors of response with a customized stratification approach would be of invaluable importance in RA, also in consideration of the large number of biologics in development targeting novel pathways currently being tested in clinical trials. In this manuscript, we review existing data and provide future perspectives with regard to the role of synovial histopathology as a potential prognostic biomarker for patient stratification in RA, in particular regarding the use of specific biologic therapies.

A small but increasing number of gene expression based biomarkers are becoming available for routine clinical use, principally in oncology and transplantation. These underscore the potential of gene expression arrays and RNA sequencing for biomarker development, but this potential has not yet been fully realized and most candidates do not progress beyond the initial report. The first part of this review examines the process of gene expression- based biomarker development, highlighting how systematic biases and confounding can significantly skew study outcomes. Adequate validation in an independent cohort remains the single best means of protecting against these concerns. The second part considers gene-expression based biomarkers in Systemic Lupus Erythematosus (SLE) and systemic vasculitis. The type 1 interferon inducible gene signature remains by far the most studied in autoimmune rheumatic disease. While initially presented as an objective, blood-based biomarker of active SLE, subsequent research has shown that it is not specific to SLE and that its association with disease activity is considerably more nuanced than first thought. Nonetheless, it is currently under evaluation in ongoing trials of anti-interferon therapy. Other candidate markers of note include a prognostic CD8+ T-cell gene signature validated in SLE and ANCA-associated vasculitis, and a disease activity biomarker for SLE derived from modules of tightly correlated genes.

MicroRNAs (miRNAs) are small non-coding RNA molecules that diversely regulate physiological and pathophysiological processes by specifically binding to different regions of targeting messenger RNAs (mRNAs). Fibrosis is characterized by the abnormal proliferation of fibroblasts and the deposition of the extracellular matrix (ECM). Both clinical and experimental animal studies have revealed that aberrant expression of miRNAs is closely associated with the development of fibrotic diseases. microRNA-21 (miR-21) is a ubiquitously expressed miRNA that is traditionally considered to be an oncogenic miRNA (oncomiR). Recent studies have demonstrated that elevated expression of miR-21 may play a vital role in the development of fibrosis by promoting the proliferation of interstitial fibroblasts and increasing the abnormal deposition of the ECM. In this review, we comprehensively summarize the role of miR-21 in tissue fibrosis. Furthermore, we highlight miR-21 as a potential diagnostic and prognostic marker and therapeutic target for fibrosis diseases.

Contradictory results exist for levels of vitamin D measured in patients with cardiovascular disease (CVD), obesity and metabolic syndrome (MetS). To clarify this, we investigated 527 participants of the STYJOBS/ EDECTA cohort (NCT00482924), with ages between 10 and 65 years. A cross-sectional analysis of anthropometry, carotid intima media thickness (IMT), and laboratory measurements for 25OH-Vitamin D3 (vitD), glucose metabolism, ultra-sensitive C-reactive protein (US-CRP), interleukin-6 (IL-6), lipids, liver-, renal-parameters, and kynurenine to tryptophan ratio were made for a selection of persons who were either obese or of normal weight. The homeostasis model assessment insulin resistance (HOMA) was also measured. As compared to the normal weight controls, significantly decreased blood levels of vitD were found in overweight/obese adults, which were not observed in the juveniles. Nevertheless, both overweight/obese juveniles and adults had significantly increased US-CRP, IL-6, HOMA, triglyceride, and LDL-cholesterol levels, and significantly decreased HDL-cholesterol levels. Juveniles with MetS displayed unchanged levels of vitD as compared to overweight/obese juveniles without MetS. Although IMT was significantly increased in both juvenile and adult overweight/obese subjects, vitD and IMT levels were not correlated. Assuming a minimum threshold of 20 ng/ml for the establishment of “low” or “normal” vitD levels, no significant alteration in IMT, metabolic, and inflammatory markers was observed in juveniles with a low vitD-status . In conclusion, although metabolic and inflammatory symptoms of obesity are displayed in juveniles, their vitD levels are unaffected. This, together with the complete lack of association with carotid IMT in both juveniles and adults, argues against a causative role of vitD in obesity-associated vascular pathology.

Though migraine and neurodegenerative disorders have a high socioeconomic impact, their therapeutic management has not been fully addressed. Their pathomechanisms are not completely understood, but glutamateinduced excitotoxicity, mitochondrial disturbances and oxidative stress all seem to play crucial roles. The overactivation of glutamate receptors contributes to the hyperexcitability observed in migraine and also to the neurodegenerative process. The kynurenine pathway of the tryptophan metabolism produces the only known endogenous Nmethyl- D-aspartate receptor antagonist, kynurenic acid, which has been proven in different preclinical studies to exert a neuroprotective effect. Influencing the kynurenine pathway might be beneficial in migraine and neurodegenerative diseases, and in the normalization of glutamatergic neurotransmission and the prevention of excitotoxic neuronal damage. The synthesis of kynurenic acid analogues may offer a valuable tool for drug development.

Leishmaniasis is a diverse group of neglected diseases caused by protozoan parasite of genus Leishmania and transmitted by the bite of a female phlebotomine sand fly. These diseases stand as a major health problem worldwide, especially in their visceral form. Despite innumerable studies on leishmaniasis, many questions are still unanswered. One of the main challenges is the presence of different Leishmania species and various clinical manifestations, complicating the therapeutic approach. There are many available antileishmanial agents, but the drug of choice is still out of reach, since almost all available drugs share several limitations and many of them are expensive with severe side effects or have a markedly reduced effectiveness. Immunosuppressed patients should also be given a special attention which represents an additional challenge. In the meantime, the combination of local and parenteral therapies with existing drugs remain a priority to improve the efficacy and to shorten the duration of the treatment. This review was undertaken to highlight the chemotherapeutic strategies, their mechanisms of action and main limitations.

Metastatic rectal cancer patients could benefit from novel therapeutic approaches. The signaling network formed by chemokines and their receptors can promote metastasis and resistance to current anticancer treatments. This study assessed the expression of chemokine receptor 4 (CXCR4) and its ligand CXCL12 immuhistochemically in stage IV rectal tumors. Paraffin-embedded primary tumor collected before and after local radiotherapy and systemic treatment with bevacizumab, oxaliplatin and capecitabine was analyzed. Receptor and ligand expression was assessed in the cytoplasm and nucleus of tumor, stromal and normal rectal crypt cells. Baseline expression of CXCR4 and CXCL12 was correlated with patients' pathologic response to treatment. At diagnosis (n=46), 89% of the rectal tumors expressed cytoplasmic CXCR4 and 81% CXCL12. Nuclear CXCR4 expression in tumor cells was present in 30% and nuclear CXCL12 expression in 35% of the tumors. After radiochemotherapy and administration of bevacizumab, nuclear CXCL12 expression was observed in 79% of residual tumors, as compared to 31% of the paired tumor samples expressing nuclear CXCL12 before treatment (P=0.001). There were no differences in CXCR4 or CXCL12 expression at baseline between the patients who had (n=9) and did not have (n=30) a pathologic complete response. Our results show that CXCR4 and CXCL12 are extensively expressed in primary rectal tumors of patients presenting with metastatic disease, while radiochemotherapy and bevacizumab further upregulate CXCL12 expression. These data indicate the importance of the CXCR4/CXCL12 axis in rectal tumor biology, and may suggest the CXCR4/CXCL12 receptor-ligand pair as a potential therapeutic target in metastatic rectal cancer.

Background: Protective effect of pretreatment with ghrelin against different forms of acute pancreatitis (AP) has been recently reported. Moreover, the healing properties of this peptide have been proved in AP evoked by cerulein. However, no studies have investigated whether the administration of ghrelin affects the course of ischemia/reperfusion-induced AP. Aim: The aim of this study was to evaluate the impact of ghrelin therapy on the course of necrotizing inflammation of the pancreas and to test its impact on peroxidation of lipids and antioxidant defense system in the acutely inflamed pancreas. Methods: Acute inflammation of the pancreas was triggered by pancreatic ischemia which was then followed by reperfusion of the gland. Ghrelin (8nmol/kg/dose) was administered to intraperitoneally twice daily, 24h after the initiation of AP. The impact of ghrelin on the course of necrotizing pancreatitis was evaluated between 1 and 21 days, and involved histological, functional, and biochemical analyses. Results: Treatment with ghrelin ameliorated morphological signs of pancreatic damage including edema, acinar cells vacuolization, hemorrhages, acinar necrosis, leukocytic infiltration of the gland, and led to its earlier regeneration. These effects were accompanied by an improvement in pancreatic blood flow, enhanced DNA synthesis, reduced serum level of pro- inflammatory interleukin-1β, decreased levels of malondialdehyde and an enhanced superoxide dismutase activity in pancreatic tissue. Conclusions: Ghrelin exerts a pronounced therapeutic effect against ischemia-reperfusion-induced pancreatitis. The mechanisms involved are likely multifactorial and are mediated by its anti-inflammatory, as well as anti-oxidative properties.

We have synthesized a novel series of N-substituted sarcosines, analogues of NFPS (N-[3-(biphenyl-4- yloxy)-3-(4-fluorophenyl)propyl]-N-methylglycine), as type-1 glycine transporter (GlyT-1) inhibitors. Several compounds incorporated a diazine ring inhibited recombinant hGlyT-1b expressed permanently in CHO cells and GlyT-1 in rat brain synaptosomal preparations. A structure-activity relationship for the newly synthesized compounds was obtained and discussed on the ground of their GlyT-1 inhibitory potencies. Replacement of the biphenyl-4-yloxy moiety in NFPS with a 5-pyridazinylphenoxy moiety (compounds 3, 4, 5, and 6) or a 2-phenyl-5- pyridazinyloxy moiety (compounds 10, 11, and 12) afforded compounds exhibiting potent inhibition on GlyT-1 activity. The GlyT-1 inhibitory properties of NFPS analogues, in which sarcosine was closed into a ring forming (methylamino)pyridazine-3-(2H)-one, were markedly reduced (compounds 13 and 14). The pyridazine-containing GlyT-1 inhibitors with in vitro GlyT-1 inhibitory potency also enhanced extracellular glycine concentrations in conscious rat striatum as was measured by microdialysis technique. In contrast to NFPS, sarcosine-based pyridazine containing GlyT-1 inhibitors failed to evoke compulsive running behavior whereas they inhibited phencyclidine- induced hypermotility in mice. It is believed that increase of extracellular concentrations of glycine by inhibition of its reuptake may probably influence positively glutamate N-methyl-D-aspartate (NMDA)-type ionotropic receptors in the central nervous system. This may have importance in the treatment of neuropsychiatric disorders associated with hypofunctional NMDA receptor-mediated glutamatergic neurochemical transmission. Thus, impaired NMDA receptor functions have been shown to be involved in the development of the negative symptoms and the cognitive deficit of schizophrenia and the treatment of these symptoms is the possible clinical indication of GlyT-1 inhibitors including those containing pyridazine moiety.