Bioavailability and therapeutic activity of alicaforsen (ISIS 2302) administered as a rectal retention enema to subjects with active ulcerative colitis

miRNA-Based Potential Biomarkers and New Molecular Insights in Ulcerative Colitis

Ulcerative colitis (UC) is a chronic non-specific inflammatory bowel disease, which usually manifests as abdominal pain, diarrhea and hematochezia. The disease often recurs and is difficult to cure. At present, the pathogenesis is not clear, but it is believed that the disease is caused by a complex interaction among immunity, heredity, environment and intestinal microflora disorders. MicroRNA (miRNA) is endogenous single-stranded non-coding RNA of 17–25 nucleotides (nts). They target the 3'Untranslated Region of a target gene and inhibit or degrade the target gene according to the extent of complementary bases. As important gene expression regulators, miRNAs are involved in regulating the expression of most human genes, and play an important role in the pathogenesis of many autoimmune diseases including UC. Studies in recent years have illustrated that abnormal expression of miRNA occurs very early in disease pathogenesis. Moreover, this abnormal expression is highly related to disease activity of UC and colitis-associated cancer, and involves virtually all key UC-related mechanisms, such as immunity and intestinal microbiota dysregulation. Recently, it was discovered that miRNA is highly stable outside the cell in the form of microvesicles, exosomes or apoptotic vesicles, which raises the possibility that miRNA may serve as a novel diagnostic marker for UC. In this review, we summarize the biosynthetic pathway and the function of miRNA, and summarize the usefulness of miRNA for diagnosis, monitoring and prognosis of UC. Then, we described four types of miRNAs involved in regulating the mechanisms of UC occurrence and development: 1) miRNAs are involved in regulating immune cells; 2) affect the intestinal epithelial cells barrier; 3) regulate the homeostasis between gut microbiota and the host; and 4) participate in the formation of tumor in UC. Altogether, we aim to emphasize the close relationship between miRNA and UC as well as to propose that the field has value for developing potential biomarkers as well as therapeutic targets for UC.

Therapeutic Oligonucleotides for Patients with Inflammatory Bowel Diseases

Introduction

The better understanding of the molecular mechanisms, which drive the pathological process in the gut of patients with Crohn's disease (CD) and patients with ulcerative colitis (UC), the major forms of inflammatory bowel diseases (IBD) in humans, has facilitated the development of novel therapeutic compounds. Among these, antisense oligonucleotides (ASOs) have been used to inhibit the expression of molecules, which sustain the IBD-associated mucosal inflammation.

Areas Covered

In this short review, we summarize experimental and clinical data on the use of ASOs in IBD.

Expert Opinion

Preclinical work indicates that the modulation of specific inflammatory pathways through the use of ASOs is highly effective and associates with low risk of adverse events. Initial clinical studies have confirmed the benefit of some ASOs even though no compound has yet reached the market. Further experimentation is warranted to establish the optimal route of administration for each ASO, ascertain whether and how long ASOs maintain their activity following administration, and identify which patient can benefit from specific ASO treatment.

Local delivery of macromolecules to treat diseases associated with the colon

Current treatments for intestinal diseases including inflammatory bowel diseases, irritable bowel syndrome, and colonic bacterial infections are typically small molecule oral dosage forms designed for systemic delivery. The intestinal permeability hurdle to achieve systemic delivery from oral formulations of macromolecules is challenging, but this drawback can be advantageous if an intestinal region is associated with the disease. There are some promising formulation approaches to release peptides, proteins, antibodies, antisense oligonucleotides, RNA, and probiotics in the colon to enable local delivery and efficacy. We briefly review colonic physiology in relation to the main colon-associated diseases (inflammatory bowel disease, irritable bowel syndrome, infection, and colorectal cancer), along with the impact of colon physiology on dosage form design of macromolecules. We then assess formulation strategies designed to achieve colonic delivery of small molecules and concluded that they can also be applied some extent to macromolecules. We describe examples of formulation strategies in preclinical research aimed at colonic delivery of macromolecules to achieve high local concentration in the lumen, epithelial-, or sub-epithelial tissue, depending on the target, but with the benefit of reduced systemic exposure and toxicity. Finally, the industrial challenges in developing macromolecule formulations for colon-associated diseases are presented, along with a framework for selecting appropriate delivery technologies.

Inflammatory bowel disease: new therapies from antisense oligonucleotides

Inflammatory bowel diseases (IBD) are chronic inflammatory conditions of the gastrointestinal tract encompassing two main clinical entities: Crohn's disease (CD) and ulcerative colitis (UC). These disorders are characterized by various grades of tissue damage and development of local complications and extra-intestinal manifestations. The cause of IBD remains unknown but accumulating evidence indicates that both CD and UC arise in genetically predisposed individuals as a result of the action of multiple environmental factors, which ultimately trigger excessive and poorly controlled immune response against antigens of the luminal flora. Despite this realization, a full understanding of IBD pathogenesis is still out of reach and, consequently, treatment is far from optimal. However, in recent years, several pathways of intestinal damage have been delineated and the improved knowledge has contributed to the development of new therapies. Various approaches have been used to either inhibit the expression and/or function of inflammatory molecules or enhance counter-regulatory mechanisms. This review summarizes the available pre-clinical and clinical data for antisense oligonucleotides and oligonucleotide-based therapy to provide a comprehensive understanding of the rationale and mechanism of action of these compounds in IBD. Key messages Preclinical studies and clinical trials show that antisense oligonucleotide (ASO)-based therapy could be of benefit in inflammatory bowel diseases. ASOs have an excellent safety profile. Technical issues emerged from clinical trials suggest that changes in drug formulation and/or route of administration could improve ASO efficacy.

Alicaforsen, an Antisense Inhibitor of Intercellular Adhesion Molecule-1, in the Treatment for Left-Sided Ulcerative Colitis and Ulcerative Proctitis

BACKGROUND

Data on the efficacy of intercellular adhesion molecule-1 antisense oligonucleotide alicaforsen in ulcerative colitis (UC) is inconsistent.

METHODS

All patients, who had received at least one dose of alicaforsen, were analyzed retrospectively. Alicaforsen's efficacy was assessed in patients treated for left-sided UC and proctitis by comparing clinical and (if applicable) endoscopic disease activity before/after treatment.

RESULTS

Twelve patients were treated for left-sided UC or proctitis. Eleven patients received a 6-week course of a once-daily 240 mg alicaforsen enema formulation. In 1 patient, treatment was discontinued, because it was found to be inefficient. Disease activity measured by the partial Mayo score and 6-point symptom score was significantly reduced after treatment (6.0 vs. 2.4, p = 0.011 and 3.7 vs. 1.4, p = 0.008). Faecal calprotectin showed a trend towards reduction (484.4 vs. 179.5 μg/g, p = 0.063). Clinical improvement was achieved in 10 patients (83.3%). In 7 patients, a relapse occurred (70%). Median duration of clinical improvement was 18.0 weeks (range 1-112). Three patients showed an ongoing improvement of >9 months. No adverse events were reported.

CONCLUSIONS

A 6-week course of alicaforsen seemed to be safe and efficacious in inducing clinical improvement in patients with left-sided UC and proctitis. Prolonged clinical improvement was observed in many but not all patients.

Alicaforsen in the treatment of pouchitis

Alicaforsen is a 20-base antisense oligonucleotide inhibiting ICAM-1 production, which is an important adhesion molecule involved in leukocyte migration and trafficking to the site of inflammation. Hitherto, alicaforsen has been granted orphan drug designation and is prescribed as an unlicensed medicine in accordance with international regulation for the treatment of pouchitis and left-sided ulcerative colitis. Given the positive results evolving from one open-label trial and one case series in patients with chronic refractory pouchitis, US FDA has agreed to a rolling submission for a license application for the treatment of pouchitis, which has been recently initiated. Whether alicaforsen leads to higher endoscopic and clinical remission rates as placebo and whether the response can be maintained in the long-term in larger studies is yet unknown. An ongoing multicenter international Phase III trial will definitely address these unanswered questions.

Alicaforsen for the treatment of inflammatory bowel disease

INTRODUCTION

Intracellular adhesion molecule-1 (ICAM-1), is a transmembrane glycoprotein of the immunoglobulin family, constitutively expressed on vascular endothelial cells and upregulated in inflamed colonic tissue. Alicaforsen, a 20 base ICAM-1 anti-sense oligonucleotide and highly selective ICAM-1 inhibitor, down-regulates ICAM-1 mRNA. Areas covered: We review mechanism of action, pharmacokinetics, pre-clinical, clinical and safety data of alicaforsen for the treatment of ulcerative colitis (UC), pouchitis and Crohn's disease (CD). Expert opinion: After 6 weeks of treatment, topical alicaforsen was significantly more effective than placebo in inducing remission in patients with moderate-severe distal UC, with treatment effects lasting up to 30 weeks. No difference was observed in head-head comparison with mesalamine topical enema, although alicaforsen appeared to have more durable treatment effect. Clinical trials of an intravenous formulation in Crohn's disease showed no significant treatment effect compared to placebo. An open-label trial in alicaforsen for pouchitis demonstrated encouraging results, now being assessed in a multi-national phase 3 trial. No major safety signals have been observed in UC patients treated with alicaforsen enemas. The potential as a novel therapy for pouchitis has led to orphan designation for this indication by the FDA and European Medicines Agency.

Ultrasound-Mediated Delivery of RNA to Colonic Mucosa of Live Mice

BACKGROUND & AIMS

It is a challenge to deliver nucleic acids to gastrointestinal (GI) tissues due to their size and need for intracellular delivery. They are also extremely susceptible to degradation by nucleases, which are ubiquitous in the GI tract. We investigated whether ultrasound, which can permeabilize tissue through a phenomenon known as transient cavitation, can be used to deliver RNA to the colonic mucosa of living mice.

METHODS

We investigated delivery of fluorescently labeled permeants to colon tissues of Yorkshire pigs ex vivo and mice in vivo. Colon tissues were collected and fluorescence was measured by confocal microscopy. We then evaluated whether ultrasound is effective in delivering small interfering (si)RNA to C57BL/6 mice with dextran sodium sulfate-induced colitis. Some mice were given siRNA against tumor necrosis factor (Tnf) mRNA for 6 days; colon tissues were collected and analyzed histologically and TNF protein levels measured by enzyme-linked immunosorbent assay. Feces were collected and assessed for consistency and occult bleeding. We delivered mRNA encoding firefly luciferase to colons of healthy C57BL/6 mice.

RESULTS

Exposure of ex vivo pig colon tissues to 20 kHz ultrasound for 1 minute increased the level of delivery of 3 kDa dextran 7-fold compared with passive diffusion (P = .037); 40 kHz ultrasound application for 0.5 seconds increased the delivery 3.3-fold in living mice (P = .041). Confocal microscopy analyses of colon tissues from pigs revealed regions of punctuated fluorescent dextran signal, indicating intracellular delivery of macromolecules. In mice with colitis, ultrasound delivery of unencapsulated siRNA against Tnf mRNA reduced protein levels of TNF in colon tissues, compared with mice with colitis given siRNA against Tnf mRNA without ultrasound (P ≤ .014), and reduced features of inflammation (P ≤ 4.1 × 10^-5). Separately, colons of mice administered an mRNA encoding firefly luciferase with ultrasound and the D-luciferin substrate had levels of bioluminescence 11-fold greater than colons of mice given the mRNA alone (P = .0025). Ultrasound exposures of 40 kHz ultrasound for 0.5 seconds were well tolerated, even in mice with acute colitis.

CONCLUSIONS

Ultrasound can be used to deliver mRNAs and siRNAs to the colonic mucosa of mice and knock down expression of target mRNAs.

Current and Future Targets for Mucosal Healing in Inflammatory Bowel Disease

The induction and subsequent maintenance of mucosal healing has emerged as one of the central therapeutic goals in the management of patients with inflammatory bowel disease (IBD) (Crohn's disease and ulcerative colitis). Current and novel treatment options are assessed regarding their therapeutic efficacy on the basis of their ability to induce mucosal healing. However, there is still substantial debate about the precise definition of mucosal healing. Here, we will give an overview regarding the definitions of mucosal healing as well as its probable effects on long-term disease behavior and finally focus on current and potential therapeutic targets to achieve this therapeutic goal in IBD patients.

Pharmacology of Antisense Drugs

Recent studies have led to a greater appreciation of the diverse roles RNAs play in maintaining normal cellular function and how they contribute to disease pathology, broadening the number of potential therapeutic targets. Antisense oligonucleotides are the most direct means to target RNA in a selective manner and have become an established platform technology for drug discovery. There are multiple molecular mechanisms by which antisense oligonucleotides can be used to modulate RNAs in cells, including promoting the degradation of the targeted RNA or modulating RNA function without degradation. Antisense drugs utilizing various antisense mechanisms are demonstrating therapeutic potential for the treatment of a broad variety of diseases. This review focuses on some of the advances that have taken place in translating antisense technology from the bench to the clinic.

Carrier-free Gene Silencing by Amphiphilic Nucleic Acid Conjugates in Differentiated Intestinal Cells

Nucleic acid therapy can be beneficial for the local treatment of gastrointestinal diseases that currently lack appropriate treatments. Indeed, several oligonucleotides (ONs) are currently progressing through clinical trials as potential treatments for inflammatory bowel diseases. However, due to low uptake of carrier-free ONs by mucosal cells, strategies aimed at increasing the potency of orally administered ONs would be highly desirable. In this work, we explored the silencing properties of chemically modified and highly resistant ONs derivatized with hydrophobic alkyl chain on intestinal epithelial cells. We screened a set of lipid-ON conjugates for the silencing of model Bcl-2 mRNA and selected 2'-deoxy-2'-fluoro-arabinonucleic acid modified ON bearing docosanoyl moiety (L-FANA) as the most potent candidate with lowest toxicity. The efficacy of L-FANA conjugate was preserved in simulated intestinal fluids and in the inverted transfection setup. Importantly, L-FANA conjugate was able to downregulate target gene expression at both mRNA and protein levels in a difficult-to-transfect polarized epithelial cell monolayer in the absence of delivery devices and membrane disturbing agents. These findings indicate that lipid-ON conjugates could be promising therapeutics for the treatment of intestinal diseases as well as a valuable tool for the discovery of new therapeutic targets.

Antisense approach to inflammatory bowel disease: prospects and challenges

Despite the great success of anti-tumour necrosis factor-based therapies, the treatment of Crohn's disease (CD) and ulcerative colitis (UC) still remains a challenge for clinicians, as these drugs are not effective in all patients, their efficacy may wane with time, and their use can increase the risk of adverse events and be associated with the development of new immune-mediated diseases. Therefore, new therapeutic targets are currently being investigated both in pre-clinical studies and in clinical trials. Among the technologies used to build new therapeutic compounds, the antisense oligonucleotide (ASO) approach is slowly gaining space in the field of inflammatory bowel diseases (IBDs), and three ASOs have been investigated in clinical trials. Systemic administration of alicaforsen targeting intercellular adhesion molecule-1, a protein involved in the recruitment of leukocytes to inflamed intestine, was not effective in CD, even though the same compound was of benefit when given as an enema to UC patients. DIMS0150, targeting nuclear factor (NF) κB-p65, a transcription factor that promotes pro-inflammatory responses, was very promising in pre-clinical studies and is currently being tested in clinical trials. Oral mongersen, targeting Smad7, an intracellular protein that inhibits transforming growth factor (TGF)-β1 activity, was safe and well tolerated by CD patients, and the results of a phase II clinical trial showed the efficacy of the drug in inducing clinical remission in patients with active disease. In this leading article, we review the rationale and the clinical data available regarding these three agents, and we discuss the challenge of using ASOs in IBD.

Where are we heading to in pharmacological IBD therapy?

After a relatively long time of failed developments and negative clinical trials in pharmacological inflammatory bowel disease (IBD) therapy we now phase a time of a great number of successful studies and new therapy principles that will most likely make it into clinical practice. This will change the landscape of IBD therapy in future markedly. Many new therapeutic principles have been developed and old ones that seemed to have failed such as anti-sense technology suddenly now provide promising results. Some initially promising therapies will need further development or have failed such as Trichuris suis ova therapy (but not helminth therapy in general), CCR9 targeted therapies or recombinant IL-10. In contrast anti-leukocate trafficking therapies appear to be quite promising. Vedolizumab is the first in class anti-integrin antibody that was approved for the therapy of CD and UC recently. Other anti-integrin antibodies and small molecule adhesion inhibitors will most likely be approved in the next years for IBD therapy. Tofacitinib, a small molecule JAK inhibitor, is a promising candidate for the treatment of UC. Phosphatidylcholine may be a future option for patients with 5-ASA refractory UC or 5-ASA intolerance. The preliminary data for Mongersen, a Smad7 antisense oligonucleotide, are promising despite some concerns about long term effect of TGFβ induction. Anti IL6 strategies will hopefully be further evaluated keeping in mind the caveat of a lack of CRP induction in anti-IL6 treated patients. Stem cell transplantation will become an option for patients that have experienced failure of established medications. Fecal microbiota transplantation and also perhaps combined probiotic therapy is a field that will be evaluated in more detail in the near future especially for UC patients. Based on these new developments treatment algorithms need to be updated. This review will reflect these current developments and give a perspective for future IBD therapy.

Systematic Review: Rectal Therapies for the Treatment of Distal Forms of Ulcerative Colitis

BACKGROUND

Many therapeutic options are available for patients with distal forms of ulcerative colitis (UC). Rectal therapies (e.g., suppositories, foams, gels, and enemas) may be recommended either alone or in combination with oral treatment. Compared with oral therapies, rectal therapies are underused in patients with distal forms of UC, although rectal therapies have favorable efficacy and safety profiles.

METHODS

This systematic review identified 48 articles for inclusion after a comprehensive PubMed search and the identification of additional relevant articles through other sources. Inclusion criteria were clinical studies examining efficacy and safety of 5-aminosalicylic acid, corticosteroid, and non-5-aminosalicylic acid rectal therapies (suppositories, foams, gels, and enemas) that induce or maintain remission in patients with ulcerative proctitis, ulcerative proctosigmoiditis, or left-sided colitis (i.e., distal forms of UC). The quality of the evidence presented was evaluated using the GRADE system.

RESULTS

Overall, a greater percentage of patients with distal forms of UC receiving 5-aminosalicylic acids or corticosteroid rectal formulations derived greater therapeutic benefit after treatment compared with patients receiving placebo. Furthermore, most uncontrolled studies of rectal therapies reported that patients with distal forms of UC had marked improvement from baseline after treatment. The overall safety profile of rectal therapies was favorable. Treatment with second-generation corticosteroids, such as budesonide and beclomethasone dipropionate, did not increase the incidence of steroid-related adverse effects.

CONCLUSIONS

The current literature supports the use of rectal therapies for both induction and maintenance of remission in patients with distal forms of UC.

MicroRNAs in inflammatory bowel diseases: paradoxes and possibilities

MicroRNAs (miRNAs) are single-stranded RNA molecules, which influence the translation of messenger RNA and hence protein synthesis. The altered expression of miRNAs in disease states in cancer and autoimmune diseases including inflammatory bowel disease is providing new insights into disease pathogenesis. This understanding is leading to consideration of the utility of miRNAs in diagnostics, prognostics, and therapeutics in inflammatory bowel disease. A literature search was conducted using the MEDLINE/PubMed databases using search terms inflammatory bowel disease, miRNA, treatment, and biomarkers.

Targeting integrins and adhesion molecules to combat inflammatory bowel disease

: The etiologies of Crohn's disease and ulcerative colitis, the 2 major forms of inflammatory bowel disease in humans, remain unknown, but experimental studies suggest that inflammatory bowel disease results from interaction between environmental and genetic factors, which promotes an exaggerated and inappropriately controlled inflammatory response that is directed against normal components of the gut flora. There is also evidence that tissue damage is due to a dynamic interplay between immune and nonimmune cells, and recruitment of lymphocytes from the blood stream to the gut wall is crucial for amplifying and sustaining the ongoing mucosal inflammation. These advances have led to the development of several compounds blocking gut homing of effector lymphocytes, which have recently been used or are now ready to move into clinical practice. This article summarizes the recent data on the use of integrin-targeting and adhesion molecule-targeting therapeutics to attenuate the detrimental inflammatory response in inflammatory bowel disease.

Leukocyte traffic blockade as a therapeutic strategy in inflammatory bowel disease

Dysregulated recruitment of leukocytes into the intestine is a characteristic feature of IBD. Several families of molecules regulate the influx of these cells into sites of inflammation within the gastrointestinal tract. Pharmacological blockade of interactions between molecules that mediate the formation of stable bonds (integrins) and their endothelial ligands has already shown clinical efficacy. Antibodies that target participant molecules have been approved by the US Federal Drug Administration for use in Crohn's, multiple sclerosis (MS) (i.e. natalizumab) and psoriasis (i.e. efalizumab). A more recent additional family of drugs, which might also interfere with lymphocyte traffic (i.e. sphingosine-1- phosphate receptor agonists: fingolimod) is in clinical use for MS and just recently entered the clinical trial stage for ulcerative colitis. In the present review we discuss basic aspects of clinically relevant molecules and compile the clinical studies that support the targeting of specific steps of the leukocyte adhesion cascade for therapeutic purposes in IBD.

Alicaforsen: An Emerging Therapeutic Agent for Ulcerative Colitis and Refractory Pouchitis

Pouchitis is a relatively common complication that develops following ileal pouch-anal anastomosis in patients with complicated ulcerative colitis (UC). Both pouchitis and UC share similarities in their development, as well as in the mechanisms involving mediators of the inflammatory process. In the recent years, the discovery and investigation of biological therapies have led to advancement in the management of these disorders, and the continuation of research on this novel area holds strong implications for a future reduction in the use of invasive surgical procedures. Alicaforsen represents one of these emerging therapeutic agents, and has demonstrated promising results in both preclinical and clinical settings. This article reviews the therapeutic effects of alicaforsen for the management of UC and refractory pouchitis, with special emphasis on the mechanism of action of this therapeutic agent and the clinical studies asserting its effectiveness.

Review article: anti-adhesion therapies for inflammatory bowel disease

BACKGROUND

A high proportion of patients with inflammatory bowel disease (IBD) do not achieve clinical remission with the current therapies including mesalazine (mesalamine), immunossupresants (IMS) and antibodies against tumour necrosis factor (anti-TNF). Moreover, IMS and anti-TNF involve a nonnegligible risk for infections and/or malignancies. The anti-adhesion molecules are one of the most interesting new treatments because of their gut-selectivity.

AIM

To review the physiopathology of the adhesion molecules and the current drugs targeting this mechanism.

METHODS

We performed a literature review in PubMed and in clinicaltrials.gov using the terms 'anti-adhesion molecules', 'inflammatory bowel disease', 'natalizumab', 'vedolizumab', 'AMG181', 'Etrolizumab', 'PF-00547659', 'AJM300', 'Alicaforsen' and 'CCX282-B' up to November 2013.

RESULTS

A total of eight drugs were found including those targeting the α4β1, α4β7 or αEβ7 integrins as well as the ICAM-1 and MAdCAM-1 addressins and the chemokine receptor 9. The rationale for these drugs is the blockade of gut-homing T lymphocytes and the ones targeting the α4β7/MAdCAM-1 interaction presented the most promising results in luminal disease. Vedolizumab, an α4β7 antibody, has completed phase 3 trials with very positive results especially for ulcerative colitis. However, many questions remain unanswered such as the effect of these therapies in perianal disease and extraintestinal manifestations.

CONCLUSIONS

The blockade of the α4β7/MAdCAM-1 interaction and especially vedolizumab is an effective and safe gut-specific treatment for IBD. Further studies are needed to clarify the efficacy and safety of the other anti-adhesion drugs and to define the specific indications of these therapies in the different scenarios of IBD.

Meta-analysis using individual patient data: efficacy and durability of topical alicaforsen for the treatment of active ulcerative colitis

BACKGROUND

The antisense ICAM-1 inhibitor alicaforsen has been studied in four phase 2 studies in ulcerative colitis (UC). Recruited patients varied as to the extent of their colitis and in the severity of disease at entry.

AIM

To investigate the efficacy of alicaforsen enema in specific UC populations. Efficacy was analysed for short-term (week 6-10) and long-term (week 30) outcomes compared with either placebo or a high-dose mesalazine (mesalamine) enema in patients with disease extent up to 40 cm from the anal verge in patients with moderate or severe disease, and in patients with both of these features.

METHODS

Individual patient data meta-analyses of 200 patients from four phase 2 studies evaluating nightly alicaforsen 240 mg enema and comparators. Patient data were pooled and analysed in a single data set. Continuous outcomes were evaluated using anova; dichotomous outcomes were evaluated using Pearson chi-square or Fisher's exact tests.

RESULTS

Alicaforsen showed superior efficacy vs. placebo in: patients with disease extent up to 40 cm, patients with moderate and severe disease and especially when both those conditions were satisfied. In these patient groups, mesalazine also showed short-term efficacy. At week 30, however, the efficacy of mesalazine waned and alicaforsen became significantly more efficacious.

CONCLUSIONS

This post hoc meta-analysis showed that alicaforsen is effective in patients with active UC, especially in patients with distal disease, which is of moderate/severe activity. The efficacy of alicaforsen was durable in these sub-groups, suggesting a disease-modifying effect. This analysis suggests that alicaforsen enema may offer an effective, potentially durable response in moderate/severe distal active UC.

Review article: strategies for the management of chronic unremitting ulcerative colitis

BACKGROUND

Chronic active ulcerative colitis (UC) is associated with significant morbidity, loss of productivity, increased colorectal cancer risk and cost. Up to 18% of patients suffer chronic active disease, with 30% requiring colectomy at 10 years. The management remains challenging given the relatively few clinical trials in this area.

AIM

To summarise the evidence regarding optimal management strategies for patients with chronic active UC of differing disease extents and degrees of treatment refractoriness.

METHOD

A literature search using the PubMed and Medline databases was performed. No time limit was set on article publication for inclusion.

RESULTS

The principles of management should focus on confirming disease activity, exclusion of alternative diagnoses, adherence and treatment escalation. Infliximab and topical tacrolimus are options in refractory proctitis, although the evidence for these therapies is limited. Both infliximab and adalimumab are effective in corticosteroid-refractory disease, although the proportions of patients achieving corticosteroid-free remission remain modest (24% at 30 weeks and 16.9% at 8 weeks respectively). Alternatives include ciclosporin and tacrolimus, and possibly methotrexate. Colectomy often leads to an improved quality of life; medical strategies unlikely to provide durable corticosteroid-free remission should not be pursued.

CONCLUSIONS

No current pharmacological treatment delivers mucosal healing in the majority of patients. Newer treatments such as vedolizumab and tofacitinib may represent valuable future therapies. Available medical options should be discussed with patients at every step of their management, with an honest appraisal of the evidence. Surgery should always be considered in patients with chronic refractory disease of any extent.

Inhibition of selective adhesion molecules in treatment of inflammatory bowel disease

Lymphocyte infiltration into the intestinal tract in inflammatory bowel disease (IBD) is mediated by interaction between α4 integrin and its specific ligands. Development of monoclonal antibodies against α4 integrin allowed targeting of lymphocyte trafficking into the intestine as a novel therapeutic intervention. Natalizumab, vedolizumab, alicaforsen AJM300, rhuMAb β7, CCX282-B, and PF-00547,659 are few of monoclonal antibodies that have shown high promise in trials with the potential for more attractive benefit:risk ratio than currently available therapies. In this review, an attempt is made to underline the therapeutic potential and the safety of anti-adhesion molecule treatment in IBD.

Modulation of lipoprotein metabolism by antisense technology: preclinical drug discovery methodology

Antisense oligonucleotides (ASOs) are a new class of specific therapeutic agents that alter the intermediary metabolism of mRNA, resulting in the suppression of disease-associated gene products. ASOs exert their pharmacological effects after hybridizing, via Watson-Crick base pairing, to a specific target RNA. If appropriately designed, this event results in the recruitment of RNase H, the degradation of targeted mRNA or pre-mRNA, and subsequent inhibition of the synthesis of a specific protein. A key advantage of the technology is the ability to selectively inhibit targets that cannot be modulated by traditional therapeutics such as structural proteins, transcription factors, and, of topical interest, lipoproteins. In this chapter, we will first provide an overview of antisense technology, then more specifically describe the status of lipoprotein-related genes that have been studied using the antisense platform, and finally, outline the general methodology required to design and evaluate the in vitro and in vivo efficacy of those drugs.

Efficient suppression of murine intracellular adhesion molecule-1 using ultrasound-responsive and mannose-modified lipoplexes inhibits acute hepatic inflammation

Hepatitis is often associated with the overexpression of various adhesion molecules. In particular, intracellular adhesion molecule-1 (ICAM-1), which is expressed on hepatic endothelial cells (HECs) in the early stage of inflammation, is involved in serious illnesses. Therefore, ICAM-1 suppression in HECs enables the suppression of inflammatory responses. Here, we developed an ICAM-1 small interfering RNA (siRNA) transfer method using ultrasound (US)-responsive and mannose-modified liposome/ICAM-1 siRNA complexes (Man-PEG(2000) bubble lipoplexes [Man-PEG(2000) BLs]), and achieved efficient HEC-selective ICAM-1 siRNA delivery in combination with US exposure. Moreover, the sufficient ICAM-1 suppression effects were obtained via this ICAM-1 siRNA transfer in vitro and in vivo, and potent anti-inflammatory effects were observed in various types of inflammation, such as lipopolysaccharide, dimethylnitrosamine, carbon tetrachloride, and ischemia/reperfusion-induced inflammatory mouse models.

CONCLUSION

HEC-selective and efficient ICAM-1 siRNA delivery using Man-PEG(2000) BLs and US exposure enables suppression of various types of acute hepatic inflammation. This novel siRNA delivery method may offer a valuable system for medical treatment where the targeted cells are HECs.

Targeting leukocyte migration and adhesion in Crohn's disease and ulcerative colitis

Crohn's disease and ulcerative colitis are two chronic inflammatory bowel diseases. Current biologic therapies are limited to blocking tumor necrosis factor alpha. However, some patients are primary non-responders, experience a loss of response, intolerance or side effects defining the urgent unmet need for novel treatments. The rapid recruitment and inappropriate retention of leukocytes is a hallmark of chronic inflammation and a potentially promising therapeutic target. We discuss the immunological mechanisms of leukocyte homing and adhesion in the gut mucosa. The interaction of lymphocytes (CD4+ T-cells, CD8+ T-cells, T(REG), T(H)1, T(H)17, B-cells), monocytes, macrophages, dendritic cells and granulocytes with endothelial and epithelial cells through integrins [α4β7 (LPAM-1), α(E)β₇ (HML1 Human Mucosal Lymphocyte Antigen 1), α₄β₁ (VLA-4), α(L)β₇, (LFA-1)] and their ligands immunoglobulin superfamily cellular adhesion molecules (CAM) (MAdCAM-1 Mucosal Addressin Cellular Adhesion Molecule 1, ICAM-1 Intercellular Cell Adhesion Molecule, VCAM-1 Vascular Cell Adhesion Molecule), fibronectin as well as chemokine receptors (CCR2, CCR4, CCR5, CCR7, CCR9, CCR10, CXCR3, CX3CR1) and chemokines [CCL5, CCL25 (TECK Thymus Expressed Chemokine), CCL28, CX3CL1, CXCL10, CXCL12] in the process of gut homing is critically reviewed and summarized in scientific cartoons. Moreover, we discuss the clinical trial results of approved and investigational antibodies and small molecules including natalizumab (anti-α₄ Tysabri®, Antegren®), AJM300 (anti-α4), etrolizumab (anti-β7, rhuMAb-Beta7), vedolizumab (anti-α4β7, LDP-02, MLN-02, MLN0002), PF-00547659 (anti-MAdCAM), Alicaforsen (anti-ICAM-1), and CCX282-B (anti-CCR9, GSK-1605786, Traficet-EN™) and their risks such as PML reported for natalizumab. Hopefully, the newer gut specific drug designs discussed in this article will have an impact on both efficacy and safety.

Anti-adhesion molecule therapy for inflammatory bowel disease

Although biologic agents directed against tumor necrosis factor alpha (TNFα) continue to be an effective therapeutic strategy for patients with inflammatory bowel disease (IBD), approximately 30% of patients with Crohn's disease (CD) who are refractory to standard treatment do not respond to induction therapy with TNFα inhibitors and, of those who initially respond, 50% or more cease to respond within a year. Moreover, their use can be associated with significant safety issues. Clearly, there is a need to target alternative pathways involved in the inflammatory process. IBD is driven by the trafficking of lymphocytes from the circulation into the gut tissue that is mediated by adhesive interactions between the lymphocytes and endothelial cells. The adhesion molecules involved represent attractive targets for the development of new therapeutics which should aid in the resolution of existing inflammation, prevent recurrence of inflammation, and may potentially lead to long-term control of disease. In this article we review current opportunities and challenges facing anti-adhesion therapy in IBD, and discusses recent clinical development efforts that have focused on having an impact on two particular adhesive interactions: α(4)-integrin/MAdCAM-1 and β(2)-integrin/ICAM-1. Of particular interest is natalizumab, a humanized monoclonal antibody against human α(4) integrin that is approved for the treatment of patients with moderately-to-severely active CD and evidence of active inflammation. This agent represents an efficacious therapeutic option for patients who do not respond to, or have failed, a TNF-α inhibitor.

Emerging drugs to treat Crohn's disease

IMPORTANCE OF THE FIELD

Inflammatory bowel diseases are chronic inflammatory diseases that comprise of two forms - Crohn's disease (CD) and ulcerative colitis (UC) - characterized by aberrant responses to luminal bacteria in genetically susceptible individuals. Whereas inflammation is limited to the large intestine in patients with UC, CD can affect all parts of the gastrointestinal tract. During disease exacerbations, pharmacological or surgical intervention is usually needed to re-establish remission; however, current therapeutic interventions cannot cure CD. As a subgroup of patients with CD will not be able to remain in remission with available drugs or suffer from side effects, new therapeutic strategies are needed.

AREAS COVERED IN THIS REVIEW

This review focuses on emerging drugs in the treatment of CD and reviews data on their efficacy and safety. An extensive review of the available literature was undertaken using MEDLINE to identify relevant studies.

WHAT THE READER WILL GAIN

The reader will learn about current therapeutic strategies in patients with CD and gain insights into emerging new drugs.

TAKE HOME MESSAGE

As modification of the clinical course of CD becomes the therapeutic paradigm, potential future treatments have to induce mucosal healing in order to prevent long-term complications. New biologics show promising results.

Antisense oligonucleotide pharmacokinetics and metabolism

BACKGROUND

The use of oligonucleotides as therapeutic agents has elicited a great deal of interest. Basic understanding and evaluation of the pharmacokinetic properties of oligonucleotides is foundational to their appropriate design and application.

OBJECTIVE

To review the primary pharmacokinetic properties that drive successful use and delivery of oligonucleotides.

METHODS

The primary data set available in the published literature for summarizing the pharmacokinetic properties of oligonucleotides exists for single strand phosphorothioate antisense oligonucleotides and their chimeric chemical modifications (second generation). Where possible, data from other classes of compounds are contrasted with this base class.

RESULTS/CONCLUSION

Although there are several different classes of oligonucleotides being developed as therapeutic agents, their pharmacokinetic properties by class are primarily a function of their backbone chemistry and the resulting chemical relationship to biological stability and plasma protein binding properties.

Colonic treatments and targets: issues and opportunities

The colon provides a plethora of therapeutic opportunities. There are multiple disease targets, drug molecules, and colon-specific delivery systems to be explored. Clinical studies highlight the potential for systemic delivery via the colon, and the emerging data on the levels of cell membrane transporters and metabolic enzymes along the gut could prove advantageous for this. Often efflux transporters and metabolic enzyme levels are lower in the colon, suggesting a potential for improved bioavailability of drug substrates at this site. The locoregional distribution of multiple metabolic enzymes (including cytochromes), efflux transporters (including P-glycoprotein and breast cancer resistance proteins), and influx transporters (including the solute carrier family) along the intestine is summarized. Local delivery to the colonic mucosa remains a valuable therapeutic option. New therapies that target inflammatory mediators could improve the treatment of inflammatory bowel disease, and old and new anticancer molecules could, when delivered topically, prove to be beneficial adjuncts to the current systemic or surgical treatments. New issues such as pharmacogenomics, chronotherapeutics, and the delivery of prebiotics and probiotics are also discussed in this review. Targeting drugs to the colon utilizes various strategies, each with their advantages and flaws. The most promising systems are considered in the light of the physiological data which influence their in vivo behavior.

Antisense inhibition of ICAM-1 expression as therapy provides insight into basic inflammatory pathways through early experiences in IBD

BACKGROUND

Alicaforsen (ISIS 2302), an antisense to intercellular adhesion molecule-1 (ICAM-1) (CD54), was designed to inhibit ICAM-1 expression. ICAM-1 seems to play a role in cell-mediated inflammation, specifically cell trafficking. For this reason, it may be useful in a variety of immune-mediated diseases, including inflammatory bowel disease.

OBJECTIVE

To evaluate the use of alicaforsen in clinical trials to understand its efficacy and side effects, as well as assess for evidence that may offer insight into disease pathways.

METHODS

We evaluate all of the available, published trials, with a focus on the prospective, randomized trials.

RESULTS/CONCLUSIONS

Systemic treatment for Crohn's disease has not revealed significant effect. Topical enemas for ulcerative colitis have demonstrated some effect in secondary outcomes, and initial studies in pouchitis are promising. In general, the compound has been well tolerated and safe.

Advances in antisense oligonucleotide development for target identification, validation, and as novel therapeutics

Antisense oligonucleotides (As-ODNs) are single stranded, synthetically prepared strands of deoxynucleotide sequences, usually 18–21 nucleotides in length, complementary to the mRNA sequence of the target gene. As-ODNs are able to selectively bind cognate mRNA sequences by sequence-specific hybridization. This results in cleavage or disablement of the mRNA and, thus, inhibits the expression of the target gene. The specificity of the As approach is based on the probability that, in the human genome, any sequence longer than a minimal number of nucleotides (nt), 13 for RNA and 17 for DNA, normally occurs only once. The potential applications of As-ODNs are numerous because mRNA is ubiquitous and is more accessible to manipulation than DNA. With the publication of the human genome sequence, it has become theoretically possible to inhibit mRNA of almost any gene by As-ODNs, in order to get a better understanding of gene function, investigate its role in disease pathology and to study novel therapeutic targets for the diseases caused by dysregulated gene expression. The conceptual simplicity, the availability of gene sequence information from the human genome, the inexpensive availability of synthetic oligonucleotides and the possibility of rational drug design makes As-ODNs powerful tools for target identification, validation and therapeutic intervention. In this review we discuss the latest developments in antisense oligonucleotide design, delivery, pharmacokinetics and potential side effects, as well as its uses in target identification and validation, and finally focus on the current developments of antisense oligonucleotides in therapeutic intervention in various diseases.

Inhibition of microRNA with antisense oligonucleotides

Antisense inhibition of microRNA (miRNA) function has been an important tool for uncovering miRNA biology. Chemical modification of anti-miRNA oligonucleotides (AMOs) is necessary to improve affinity for target miRNA, stabilize the AMO to nuclease degradation, and to promote tissue uptake for in vivo delivery. Here I summarize the work done to evaluate the effectiveness of various chemically modified AMOs for use in cultured cells and rodent models, and outline important issues to consider when inhibiting miRNAs with antisense oligonucleotides.

Therapeutic potential for microRNAs

MiRNAs are a conserved class of non-coding RNAs that negatively regulate gene expression post-transcriptionally. Although their biological roles are largely unknown, examples of their importance in cancer, metabolic disease, and viral infection are accumulating, suggesting that they represent a new class of drug targets in these and likely many other therapeutic areas. Antisense oligonucleotide approaches for inhibiting miRNA function and siRNA-like technologies for replacement of miRNAs are currently being explored as tools for uncovering miRNA biology and as potential therapeutic agents. The next few years should see significant progress in our understanding of miRNA biology and the advancement of the technology for therapeutic modulation of miRNA activity.

Safety and efficacy of two dose formulations of alicaforsen enema compared with mesalazine enema for treatment of mild to moderate left-sided ulcerative colitis: a randomized, double-blind, active-controlled trial

BACKGROUND

Alicaforsen is an antisense oligonucleotide inhibitor of intercellular adhesion molecule 1 protein expression with activity in subjects with ulcerative colitis and pouchitis.

AIM

To compare the effects of alicaforsen enema to standard of care mesalazine (mesalamine) enema in subjects with mild to moderate active left-sided ulcerative colitis.

METHOD

A randomized, double-blind, active-controlled multicentre clinical trial. Subjects received a nightly enema of 120 mg alicaforsen (n=55), 240 mg alicaforsen (n=50), or 4 g mesalazine (n=54) for 6 weeks, followed by a 24-week monitoring period. The primary end point was Disease Activity Index at week 6. Clinical improvement, remission and relapse were secondary end points.

RESULTS

No significant difference was observed between treatment arms in the primary end point. However, the median duration of response to alicaforsen enema treatment was two- to threefold longer (128 and 146 days) in comparison with mesalazine (54 days). Complete mucosal healing occurred in 24% of the 240 mg alicaforsen group, when compared with 17% in the mesalazine.

CONCLUSIONS

Alicaforsen enema demonstrated an acute response and safety profile similar to mesalazine enema, but was differentiated by a more durable response. The extended length of remission suggests that alicaforsen enema treatment may have a disease modifying effect.