Apremilast: a novel PDE4 inhibitor in the treatment of autoimmune and inflammatory diseases

An Update on the Latest Developments in Nonsteroidal Topical Therapy for Atopic Dermatitis

The author provides a thorough review of the latest topical treatment approaches for atopic dermatitis. Some agents are currently available in the marketplace, while others are in development. Modes of action, including phosphodiesterase-4 inhibition, aryl hydrocarbon receptor activation, and Janus kinase inhibition are discussed. Emphasis is placed on therapeutic approaches related to modes of action, with clinical data included.

Apremilast Normalizes Gene Expression of Inflammatory Mediators in Human Keratinocytes and Reduces Antigen-Induced Atopic Dermatitis in Mice

Background

Apremilast, an oral phosphodiesterase (PDE) 4 inhibitor, has demonstrated efficacy in psoriasis, while its efficacy in atopic dermatitis (AD) was found to be modest. AD is a chronic inflammatory skin disease associated with activation of T helper (Th) 2 and Th17 immunity and a compromised epidermal barrier.

Objective

The objectives of this study were to examine the expression of PDE4 isoforms in skin from healthy subjects and AD patients, and to determine the effects of apremilast on AD-related inflammatory markers in vitro and in murine models of AD.

Methods

The expression of PDE4 isoforms (A, B, C, and D) in skin biopsies from healthy subjects and AD patients was evaluated using immunohistochemistry and digital image analysis. Using quantitative real-time reverse-transcriptase polymerase chain reaction, we evaluated the effects of apremilast on gene expression in adult human epidermal keratinocytes (HEKa) stimulated by Th2 and Th17 cytokines, and in two mouse models of antigen-induced AD.

Results

Expression of PDE4 isoforms increased up to three-fold in the epidermis of AD patients versus healthy skin. In interleukin (IL)-4 and IL-17-stimulated HEKa cells, apremilast significantly changed the expression of ILs, including IL-12/IL-23p40 and IL-31, and alarmins S100A7, S100A8, and S100A12. In mouse models of AD, apremilast significantly reduced ear swelling and monocyte chemoattractant protein-1 expression.

Conclusion

PDE4 is overexpressed in AD skin compared with normal skin, and inflammatory gene expression by human keratinocytes and mouse dermatitis can be modulated by apremilast.

Apremilast increases IL-10-producing regulatory B cells and decreases proinflammatory T cells and innate cells in psoriatic arthritis and psoriasis

OBJECTIVES

Psoriatic arthritis (PsA) and psoriasis are immune-mediated inflammatory diseases sharing common immunological mechanisms. Regulatory B cells (Breg cells) producing IL-10 (B10 cells), a critical anti-inflammatory B-cell subset, were found to be decreased in both PsA and psoriasis. Apremilast, a phosphodiesterase-4(PDE4) inhibitor, increases IL-10 and therefore, we examined the effect of apremilast on Breg cells.

METHODS

Fifty patients, including 20 with PsA and 30 with psoriasis, were included in the study. The effect of apremilast on Breg cells at 3, 6 and 12 months post-treatment, was examined by flow cytometry in ODN2006 (TLR9)-stimulated peripheral blood mononuclear cells and magnetically-isolated cells. Th1 cells, Th17 cells and NKT were also measured.

RESULTS

Ex vivo stimulated cell analysis identified that post-apremilast (IL-10+CD19+) B10 cells were increased in all PsA and psoriasis patients and correlated with psoriatic skin and joint clinical improvement. Apremilast decreased IFNγ(+) T and NKT cells and IL-17(+)NKT cells. B10 cells also inversely correlated with Th1 cells, and IFNγ(+)NKT cells.

CONCLUSION

These results suggest that Breg cells are a major target of apremilast in PsA and psoriasis and that apremilast-induced increase of Breg cells is associated with a decrease of Th1 cells, IFNγ-producing NKT cells and IL-17-producing NKT cells.

Interleukin-23 pathway at the enthesis: The emerging story of enthesitis in spondyloarthropathy

The inflammatory disorders collectively termed the seronegative spondyloarthropathies (SpA) include ankylosing spondylitis (AS), psoriatic arthritis (PsA), reactive arthritis, the arthritis associated with inflammatory bowel disease including Crohn's disease and ulcerative colitis, the arthritis related to anterior uveitis, and finally, somewhat controversially Behcet's disease. All of these diseases are associated with SNPs in the IL-23R or the interleukin-23 (IL-23) cytokine itself and related downstream signaling JAK pathway genes and the interleukin-17 (IL-17) pathway. In rheumatoid arthritis, the target of the immune response is the synovium but the SpA disorders target the tendon, ligament, and joint capsule skeletal anchorage points that are termed entheses. The discovery that IL-23R-expressing cells were ensconced in healthy murine enthesis, and other extraskeletal anchorage points including the aortic root and the ciliary body of the eye and that systemic overexpression of IL-23 resulted in a severe experimental SpA, confirmed a fundamentally different immunobiology to rheumatoid arthritis. Recently, IL-23R-expressing myeloid cells and various innate and adaptive T cells that produce IL-17 family cytokines have also been described in the human enthesis. Blockade of IL-23 pathway with either anti-p40 or anti-p19 subunits has resulted in some spectacular therapeutic successes in psoriasis and PsA including improvement in enthesitis in the peripheral skeleton but has failed to demonstrate efficacy in AS that is largely a spinal polyenthesitis. Herein, we discuss the known biology of IL-23 at the human enthesis and highlight the remarkable emerging story of this unique skeletal tissue.

Drug repurposing to improve treatment of rheumatic autoimmune inflammatory diseases

The past century has been characterized by intensive efforts, within both academia and the pharmaceutical industry, to introduce new treatments to individuals with rheumatic autoimmune inflammatory diseases (RAIDs), often by 'borrowing' treatments already employed in one RAID or previously used in an entirely different disease, a concept known as drug repurposing. However, despite sharing some clinical manifestations and immune dysregulation, disease pathogenesis and phenotype vary greatly among RAIDs, and limited understanding of their aetiology has made repurposing drugs for RAIDs challenging. Nevertheless, the past century has been characterized by different 'waves' of repurposing. Early drug repurposing occurred in academia and was based on serendipitous observations or perceived disease similarity, often driven by the availability and popularity of drug classes. Since the 1990s, most biologic therapies have been developed for one or several RAIDs and then tested among the others, with varying levels of success. The past two decades have seen data-driven repurposing characterized by signature-based approaches that rely on molecular biology and genomics. Additionally, many data-driven strategies employ computational modelling and machine learning to integrate multiple sources of data. Together, these repurposing periods have led to advances in the treatment for many RAIDs.

Neuroinflammation as a Factor of Neurodegenerative Disease: Thalidomide Analogs as Treatments

Neuroinflammation is initiated when glial cells, mainly microglia, are activated by threats to the neural environment, such as pathogen infiltration or neuronal injury. Although neuroinflammation serves to combat these threats and reinstate brain homeostasis, chronic inflammation can result in excessive cytokine production and cell death if the cause of inflammation remains. Overexpression of tumor necrosis factor-α (TNF-α), a proinflammatory cytokine with a central role in microglial activation, has been associated with neuronal excitotoxicity, synapse loss, and propagation of the inflammatory state. Thalidomide and its derivatives, termed immunomodulatory imide drugs (IMiDs), are a class of drugs that target the 3'-untranslated region (3'-UTR) of TNF-α mRNA, inhibiting TNF-α production. Due to their multi-potent effects, several IMiDs, including thalidomide, lenalidomide, and pomalidomide, have been repurposed as drug treatments for diseases such as multiple myeloma and psoriatic arthritis. Preclinical studies of currently marketed IMiDs, as well as novel IMiDs such as 3,6'-dithiothalidomide and adamantyl thalidomide derivatives, support the development of IMiDs as therapeutics for neurological disease. IMiDs have a competitive edge compared to similar anti-inflammatory drugs due to their blood-brain barrier permeability and high bioavailability, with the potential to alleviate symptoms of neurodegenerative disease and slow disease progression. In this review, we evaluate the role of neuroinflammation in neurodegenerative diseases, focusing specifically on the role of TNF-α in neuroinflammation, as well as appraise current research on the potential of IMiDs as treatments for neurological disorders.

[Gastrointestinal side effects of apremilast : Characterization and management]

Apremilast is an oral inhibitor of phosphodiesterase-4 (PDE4) that is licensed for the second-line treatment of psoriasis and psoriatic arthritis. Data from several phase III clinical trials and real-world studies showed a good benefit-risk profile, with diarrhea and nausea as the most common adverse events. Diarrhea and nausea most frequently occurred during the first month of treatment. In most cases, they were mild or moderate in severity and tended to resolve over time with continued dosing and without intervention. In this review we summarize available data on gastrointestinal side effects of apremilast in patients with psoriasis and psoriasis arthritis and provide practical strategies for managing these symptoms.

Triazole-Pyridine Dicarbonitrile Targets Phosphodiesterase 4 to Induce Cytotoxicity in Lung Carcinoma Cells

Phosphodiesterase 4 (PDE4) is a key enzyme involved in the hydrolysis of cyclic adenosine monophosphate (cAMP) and widely expressed in several types of cancers. The inhibition of PDE4 results in an increased concentration of intracellular cAMP levels that imparts the anti-inflammatory response in the target cells. In the present report, two series of triazolo-pyridine dicarbonitriles and substituted dihydropyridine dicarbonitriles were synthesized using green protocol (TBAB in refluxed water). We next evaluated the title compounds for their cytotoxicity towards lung cancer (A549) cells and identified 7'-[4-(methylsulfonyl)phenyl]-5'-oxo-1',5'-dihydrospiro[cyclohexane-1,2'-[1,2,4]triazolo[1,5-a]pyridine]-6',8'-dicarbonitrile (5h) and 7'-(1-methyl-1H-imidazol-2-yl)-5'-oxo-1',5'-dihydrospiro[cyclohexane-1,2'-[1,2,4]triazolo[1,5-a]pyridine]-6',8'-dicarbonitrile (5j) as lead analogs with the IC₅₀ values of 15.2 and 24.1 μm, respectively. Furthermore, all the new compounds were tested for PDE4 inhibitory activity and 5j showed relatively good inhibitory activity towards PDE4 with inhibition of 50.9 % at 10 μm. In silico analysis demonstrated the favorable interaction of the title compounds with the target enzyme. Taken together, the present study introduces a new scaffold for the development of novel PDE4 inhibitors to fight against inflammatory diseases.

Interventions to chronic prostatitis/Chronic pelvic pain syndrome treatment. Where are we standing and what's next?

Chronic prostatitis/chronic pelvic pain syndrome (CP/CPPS) is a frustrating syndrome. The pathogenesis and state of the art treatment of CP/CPPS are not known. A wide variety of therapies including anti-inflammatories, antibiotics, alpha-blockers, neuropathic pain modulators, and 5α-reductase inhibitors are in practice. These treatment strategies focus on alleviating symptoms in specific domains without treating root-cause and therapeutic outcome is far from satisfactory. We review the literature on current pharmacological treatments for CP/CPPS in detail and suggest future perspectives to modify the treatment strategies. We suggest that introducing novel treatment strategies such as gene editing, and T_regs expressing chimeric receptors may improve the treatment outcomes by inducing immune tolerance and controlling expression of pro-inflammatory cytokines.

Therapeutic opportunities in colon cancer: Focus on phosphodiesterase inhibitors

Despite novel technologies, colon cancer remains undiagnosed and 25% of patients are diagnosed with metastatic colon cancer. Resistant to chemotherapeutic agents is one of the major problems associated with treating colon cancer which creates the need to develop novel agents targeting towards newer targets. A phosphodiesterase is a group of isoenzyme, which, hydrolyze cyclic nucleotides and thereby lowers intracellular levels of cAMP and cGMP leading to tumorigenic effects. Many in vitro and in vivo studies have confirmed increased PDE expression in different types of cancers including colon cancer. cAMP-specific PDE inhibitors increase intracellular cAMP that leads to activation of effector molecules-cAMP-dependent protein kinase A, exchange protein activated by cAMP and cAMP gated ion channels. These molecules regulate cellular responses and exert its anticancer role through different mechanisms including apoptosis, inhibition of angiogenesis, upregulating tumor suppressor genes and suppressing oncogenes. On the other hand, cGMP specific PDE inhibitors exhibit anticancer effects through cGMP dependent protein kinase and cGMP dependent cation channels. Elevation in cGMP works through activation of caspases, suppression of Wnt/b-catenin pathway and TCF transcription leading to inhibition of CDK and survivin. These studies point out towards the fact that PDE inhibition is associated with anti-proliferative, anti-apoptotic and anti-angiogenic pathways involved in its anticancer effects in colon cancer. Thus, inhibition of PDE enzymes can be used as a novel approach to treat colon cancer. This review will focus on cAMP and cGMP signaling pathways leading to tumorigenesis and the use of PDE inhibitors in colon cancer.

Systemic rheumatic diseases: From biological agents to small molecules

The development of biologics and small oral molecules has recently changed the scenario of pharmacologic treatment of systemic rheumatic diseases and it has become a real revolution. These drugs have innovative mechanisms of action, based on the inhibition of specific molecular or cellular targets directly involved in disease pathogenesis. This new scenario has lead to a regular update of the management recommendations of several institutions, such as those for Rheumatoid Arthritis treatment that address the use of conventional and biologic therapies including TNF inhibitors (adalimumab, certolizumab pegol, etanercept, golimumab, infliximab), abatacept, rituximab, IL-6 inhibitors (tocilizumab and sarilumab), biosimilars and small oral molecules (the JAK inhibitors tofacitinib and baricitinib). Monotherapy, combination therapy, treatment strategies (such as treat-to-target) and the targets of sustained clinical remission or low disease activity are the final goal of the guidelines for rheumatic patients management. In another condition represented by Axial Spondyloarthritis guidelines suggest to start first with non-steroidal anti-inflammatory drugs to improve lifestyle and reduce spine inflammation, but if this is not achieved in 2-4 weeks it is important to consider the use of local therapies (i.e. glucocorticoid injections) or to start biologic therapy such as TNF inhibitors and then eventually switching to another TNF inhibitor or swapping to IL-17 inhibitor. In the case of active Psoriatic Arthritis, guidelines suggest to start with non-steroidal anti-inflammatory drugs and even local glucocorticoid injections especially for oligoarthritis, then to start conventional therapies if lack of efficacy, and finally start biologics or small oral molecules in the presence of drugs toxicity, unfavorable prognostic factors and still active arthritis. In several cases, active Psoriatic Arthritis patients develop a complex clinical condition with comorbidities such as diabetes, inflammatory bowel disease and high risk of infections, and for this reason the American College of Rheumatology and the National Psoriasis Foundation have developed specific guidelines for their management. Biologic and new small molecules therapies are very expensive, but the availability of biosimilars offers the opportunity of reducing the treatment cost and significantly decreasing the cost of originators as well. In fact, we live in a period characterized by the need to rationalize costs of these drugs, to allow treating a higher number of patients and to maintain a homogeneous possibility of treatment choice. For these reasons, we need to follow scientific guidelines and patients' clinical conditions to choose the correct treatment, also based on the economic burden of therapies.

Off-label studies on apremilast in dermatology: a review

Purpose: Apremilast is a phosphodiesterase-4 inhibitor FDA approved for psoriatic arthritis and moderate to severe plaque psoriasis. In recent years, multiple studies have suggested other potential uses for apremilast in dermatology. A summary of these various studies will be a valuable aid to dermatologists considering apremilast for an alternative indication.Materials and methods: The PubMed/MEDLINE and ClinicalTrials.gov databases were queried with the term 'apremilast,' with results manually screened to identify published data on off-label uses of apremilast. The article was structured by the quality of evidence available.Results: Apremilast use in dermatology beyond plaque psoriasis and psoriatic arthritis is frequently described in the literature, with a mixture of positive and negative results. Randomized controlled data is available for Behçet's disease, hidradenitis suppurativa, nail/scalp/palmoplantar psoriasis, alopecia areata, and atopic dermatitis.Conclusion: The relatively safe adverse effect profile of apremilast and its broad immunomodulatory characteristics may make it a promising option in the future for patients with difficult to treat diseases in dermatology, refractory to first line therapies, but further studies will be necessary to clarify its role.

IL-12/IL-23p40 identified as a downstream target of apremilast in ex vivo models of arthritis

BACKGROUND

Apremilast (Otezla®) is a phosphodiesterase 4 (PDE4) inhibitor approved for the treatment of psoriasis and psoriatic arthritis (PsA), but the reason why apremilast shows clinical effect is not fully understood. The objective of this study was to study the downstream effects of apremilast on cells of inflamed joints in immune-mediated inflammatory arthritis.

METHODS

Synovial fluid was obtained from patients with active rheumatoid arthritis (RA), PsA or peripheral spondyloarthritis (SpA; n = 18). The in vitro models consisted of synovial fluid mononuclear cells (SFMCs) or fibroblast-like synovial cells (FLSs) cultured for 48 h, SFMCs cultured for 21 days, an osteoclast pit formation assay, and a mineralization assay.

RESULTS

In SFMCs cultured for 48 h, apremilast decreased the production of interleukin (IL)-12/IL-23p40 (the shared subunit of IL-12 and IL-23), colony-stimulating factor 1, CD6, and CD40 and increased the production of C-X-C motif chemokine 5 dose-dependently. Apremilast had a very different response signature compared with the tumor necrosis factor alpha inhibitor adalimumab with a substantially greater inhibition of IL-12/IL-23p40. In SFMCs cultured for 21 days, apremilast increased the secretion of IL-10. In FLS cultures, apremilast decreased matrix metalloproteinase-3 production. Apremilast decreased osteoclastogenesis but did not affect mineralization by human osteoblasts.

CONCLUSION

This study reveals the downstream effects of apremilast in ex vivo models of arthritis with a strong inhibition of IL-12/IL-23p40 by SFMCs. Our findings could explain some of the efficacy of apremilast seen in IL-12/IL-23-driven immune-mediated inflammatory diseases such as psoriasis and PsA.

TAS-203, an oral phosphodiesterase 4 inhibitor, exerts anti-inflammatory activities in a rat airway inflammation model

Cyclic adenosine monophosphate (cAMP) is a key intracellular second messenger, which is degraded by phosphodiesterase 4 (PDE4). PDE4 suppresses cAMP levels, and thus stimulates the activity of inflammatory cells. Therefore, PDE4 has been considered as a therapeutic target for airway inflammatory diseases including asthma and chronic obstructive pulmonary disease (COPD). Roflumilast, an approved PDE4 inhibitor, has been shown to have clinical benefits in COPD. However, central nervous system-related side effects including nausea and vomiting have limited the therapeutic index of roflumilast. Moreover, although airway mucus hypersecretion is the characteristic feature, which is associated with the severity and prognosis, the inhibitory effect of roflumilast on sputum production is limited to a minority of patients. In this study, we demonstrate the inhibitory effects of TAS-203, which is an orally active PDE4 inhibitor associated with a lowered emetic effect, on airway inflammation and mucus hypersecretion. A cell-based assay showed TAS-203 treatment suppressed epidermal growth factor (EGF)-induced mucin MUC5AC expression. TAS-203 also suppressed monocyte chemoattractant protein-1 (MCP-1), interleukin (IL)-5 and IL-13 production in a Sephadex-induced airway inflammation model, and the number of infiltrating cells in bronchoalveolar lavage (BAL) fluid. TAS-203 caused marked reduction of goblet cell hyperplasia in a histopathological analysis of airway epithelium. Furthermore, TAS-203 suppressed 5-hydroxytryptamine (5-HT)-induced airway hyperresponsiveness (AHR). In addition, we preliminarily confirmed TAS-203 prevents airway MUC5AC production in BAL fluid, and shows lower specific airway resistance (sRaw) in a cigarette smoke-induced COPD-like model. Our data suggest that TAS-203 might be useful in the treatment of airway inflammatory disease.

Targeting Metalloenzymes for Therapeutic Intervention

Metalloenzymes are central to a wide range of essential biological activities, including nucleic acid modification, protein degradation, and many others. The role of metalloenzymes in these processes also makes them central for the progression of many diseases and, as such, makes metalloenzymes attractive targets for therapeutic intervention. Increasing awareness of the role metalloenzymes play in disease and their importance as a class of targets has amplified interest in the development of new strategies to develop inhibitors and ultimately useful drugs. In this Review, we provide a broad overview of several drug discovery efforts focused on metalloenzymes and attempt to map out the current landscape of high-value metalloenzyme targets.

Nonribosomal peptides and polyketides of Burkholderia: new compounds potentially implicated in biocontrol and pharmaceuticals

Bacteria belonging to the genus Burkholderia live in various ecological niches and present a significant role in the environments through the excretion of a wide variety of secondary metabolites including modular nonribosomal peptides (NRPs) and polyketides (PKs). These metabolites represent a widely distributed biomedically and biocontrol important class of natural products including antibiotics, siderophores, and anticancers as well as biopesticides that are considered as a novel source that can be used to defend ecological niche from competitors and to promote plant growth. The aim of this review is to present all NRPs produced or potentially produced by strains of Burkholderia, as NRPs represent a major source of active compounds implicated in biocontrol. The review is a compilation of results from a large screening we have performed on 48 complete sequenced genomes available in NCBI to identify NRPS gene clusters, and data found in the literature mainly because some interesting compounds are produced by strains not yet sequenced. In addition to NRPs, hybrids NRPs/PKs are also included. Specific features about biosynthetic gene clusters and structures of the modular enzymes responsible for the synthesis, the biological activities, and the potential uses in agriculture and pharmaceutical of NRPs and hybrids NRPs/PKs will also be discussed.

Topical application of anthranilate derivatives ameliorates psoriatic inflammation in a mouse model by inhibiting keratinocyte-derived chemokine expression and neutrophil infiltration

Psoriasis is an inflammatory autoimmune skin disorder possessing a complex etiology related to genetic and environmental triggers. Keratinocytes show a potential role for the origin of psoriasis. In this study, we estimated the efficiency of 2 anthranilate derivatives-(E)-4-( N-{2-[1-(hydroxyimino)ethyl]phenyl}sulfamoyl)phenyl pivalate (HFP031) and butyl 2-[2-(2-fluorophenyl)acetamido]benzoate (HFP034)-on psoriasis amelioration in a mouse model. The results showed that topical treatment with both compounds could attenuate epidermal thickness and scaling in an imiquimod (IMQ)-induced psoriasis mouse model via decreased expression of cytokines and chemokines [C-X-C chemokine ligand (CXCL)1 and CXCL2], leading to the reduction of neutrophilic abscess in the skin. The in vivo cutaneous absorption of HFP034 was 7.6-fold greater than that of HFP031. Both compounds caused negligible irritation on healthy mouse skin. In addition, we examined the effect of the anthranilate derivatives on chemokine expression in IMQ-treated HaCaT keratinocytes. Our results elucidated a mechanism for anti-inflammatory activity of HFP034 that involved the elevation of intracellular cAMP concentration, suppression of NF-κB activity, and attenuation of neutrophil chemoattractant expression. These results suggest that HFP034 could increase the cutaneous concentration of cAMP to suppress neutrophil infiltration into the skin. Topically applied HFP034 may demonstrate a potential for future clinical application as a novel therapy for psoriasis treatment.-Lin, Z.-C., Hsieh, P.-W., Hwang, T.-L., Chen, C.-Y., Sung, C. T., Fang, J.-Y. Topical application of anthranilate derivatives ameliorates psoriatic inflammation in a mouse model by inhibiting keratinocyte-derived chemokine expression and neutrophil infiltration.

Determination of a PDE4 inhibitor Hemay005 in human plasma and urine by UPLC-MS/MS and its application to a PK study

AIM

Hemay005 is a novel small-molecule inhibitor of phosphodiesterase-4 developed for the treatment of psoriasis. Measurement of Hemay005 in biological samples is critical for evaluation of its pharmacokinetics in clinical studies. Methodology & results: Plasma and urine samples were extracted and then chromatographed on an Acquity UPLC HSS T3 column with a gradient elution. Detection was performed on a Xevo TQ-S tandem mass spectrometer using negative ESI.

CONCLUSION

For the first time, a sensitive and robust ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was established and validated for the quantitative determination of Hemay005 in human plasma and urine, and it was successfully applied to evaluate the pharmacokinetics of Hemay005 in healthy subjects in a first-in-human study.

Apremilast Alters Behavioral Responses to Ethanol in Mice: I. Reduced Consumption and Preference

BACKGROUND

Phosphodiesterase type 4 (PDE4) inhibitors produce widespread anti-inflammatory effects and reduce ethanol (EtOH) consumption in several rodent models. These drugs are potential treatments for several diseases, including central nervous system disorders, but clinical use is limited by their emetic activity. Apremilast is a selective PDE4 inhibitor with fewer gastrointestinal side effects that is FDA-approved for the treatment of psoriasis.

METHODS

We measured the acute and chronic effects of apremilast on EtOH consumption in male and female C57BL/6J mice using the continuous and intermittent 24-hour 2-bottle choice drinking models. We also studied the effects of apremilast on preference for sucrose or saccharin, spontaneous locomotor activity, and blood EtOH clearance. Finally, apremilast levels in plasma, liver, and brain were measured 1 or 2 hours after injection.

RESULTS

In the continuous and intermittent drinking tests, apremilast (15 to 50 mg/kg, p.o.) dose dependently reduced EtOH intake and preference in male and female mice. Higher doses of apremilast (30 to 50 mg/kg) also reduced total fluid intake in these mice. Chronic administration of apremilast (20 mg/kg) produced a stable reduction in EtOH consumption in both drinking tests with no effect on total fluid intake. The drinking effects were reversible after drug treatment was replaced with vehicle administration (saline) for 2 to 4 days. Six daily apremilast injections did not alter preference for saccharin or sucrose in male or female mice. Apremilast (20 mg/kg) transiently decreased spontaneous locomotor activity and did not alter blood EtOH clearance. The highest levels of apremilast were found in liver followed by plasma and brain.

CONCLUSIONS

Apremilast produced stable reductions in voluntary EtOH consumption and was rapidly distributed to plasma and tissues (including the brain), suggesting that it may be an improved PDE4 inhibitor for medication development and repurposing efforts to treat alcohol abuse.

East Indian Sandalwood Oil Is a Phosphodiesterase Inhibitor: A New Therapeutic Option in the Treatment of Inflammatory Skin Disease

Cyclic adenosine monophosphate phosphodiesterases (PDEs) regulate pro-inflammatory cytokine production. One isoform, PDE4, is overactive in chronic relapsing inflammatory skin diseases: psoriasis and eczema/atopic dermatitis, and in several cancers. East Indian sandalwood oil (EISO) has significant anti-inflammatory properties. Here, we report that 75% of pediatric eczema/atopic dermatitis patients treated with topical EISO formulations achieved a >50% reduction in their Eczema Area and Severity Index score. EISO treatment of a psoriasis model reduced PDE4 expression and reversed histopathology. EISO directly inhibited PDE enzymatic activity in vitro. In lipopolysaccharide-stimulated human dermal fibroblast, BEAS-2B, A549, and THP-1 cells, EISO suppressed total cellular PDE activity, PDE4, and 7 transcript levels, nuclear factor kappa B (NF-κB) activation, and pro-inflammatory cytokines/chemokine production. These results suggest that EISO anti-inflammatory activity is mediated through suppressing PDE activity, thus facilitating cAMP-regulated inhibition of NF-κB and indicate EISO as an attractive natural therapeutic for chronic and acute inflammatory disorders.

Inhibition of Phosphodiesterase 4 by FCPR03 Alleviates Lipopolysaccharide-Induced Depressive-Like Behaviors in Mice: Involvement of p38 and JNK Signaling Pathways

Inflammatory responses induced by peripheral administration of lipopolysaccharide (LPS) triggers depressive-like behavioral syndrome in rodents. Inhibition of phosphodiesterase 4 (PDE4) produces a robust anti-inflammatory effect in inflammatory cells. Unfortunately, archetypal PDE4 inhibitors cause intolerable gastrointestinal side-effects, such as vomiting and nausea. N-isopropyl-3-(cyclopropylmethoxy)-4-difluoromethoxy benzamide (FCPR03) is a novel, selective PDE4 inhibitor with little, or no, emetic potency. Our previous studies show that FCPR03 is effective in attenuating neuroinflammation in mice treated with LPS. However, whether FCPR03 could exert antidepressant-like effect induced by LPS is largely unknown. In the present study, mice injected intraperitoneally (i.p.) with LPS was established as an in vivo animal model of depression. The antidepressant-like activities of FCPR03 were evaluated using a tail suspension test, forced swimming test, and sucrose preference test. We demonstrated that administration of FCPR03 (1 mg/kg) produced antidepressant-like effects in mice challenged by LPS, as evidenced by decreases in the duration of immobility in the forced swim and tail suspension tests, while no significant changes in locomotor activity were observed. FCPR03 also increased sucrose preference in mice treated with LPS. In addition, treatment with FCPR03 abolished the downregulation of brain-derived neurotrophic factor induced by LPS and decreased the level of corticosterone in plasma. Meanwhile, periphery immune challenge by LPS induced enhanced phosphorylation of p38-mitogen activated protein kinase (p38) and c-Jun N-terminal kinase (JNK) in both the cerebral cortex and hippocampus in mice. Interestingly, treatment with FCPR03 significantly blocked the role of LPS and reduced the levels of phosphorylated p38 and JNK. Collectively, these results indicate that FCPR03 shows antidepressant-like effects in mice challenged by LPS, and the p38/JNK signaling pathway is possibly involved in this process. Our findings suggest that FCPR03 is a potential compound for the prevention or treatment of depression.

Novel butanehydrazide derivatives of purine-2,6-dione as dual PDE4/7 inhibitors with potential anti-inflammatory activity: Design, synthesis and biological evaluation

A novel butanehydrazide derivatives of purine-2,6-dione designed using a ligand-based approach were synthesized and their in vitro activity against both PDE4B and PDE7A isoenzymes was assessed. The 7,8-disubstituted purine-2,6-dione derivatives 31, 34, 37, and 40 appeared to be the most potent PDE4/7 inhibitors with IC₅₀ values in the range of that of the reference rolipram and BRL-50481, respectively. Moreover, docking studies explained the importance of N-(2,3,4-trihydroxybenzylidene)butanehydrazide substituent in position 7 of purine-2,6-dione core for dual PDE4/7 inhibitory properties. The inhibition of both the cAMP-specific PDE isoenzymes resulted in a strong anti-TNF-α effect. Compounds 31, 34, and 37 in the in vivo study in rats with LPS-induced endotoxemia decreased the maximum concentration of this proinflammatory cytokine by 53, 84 and 88%, respectively.

Discovery and Optimization of Thiazolidinyl and Pyrrolidinyl Derivatives as Inhaled PDE4 Inhibitors for Respiratory Diseases

Phosphodiesterase 4 (PDE4) is a key cAMP-metabolizing enzyme involved in the pathogenesis of inflammatory disease, and its pharmacological inhibition has been shown to exert therapeutic efficacy in chronic obstructive pulmonary disease (COPD). Herein, we describe a drug discovery program aiming at the identification of novel classes of potent PDE4 inhibitors suitable for pulmonary administration. Starting from a previous series of benzoic acid esters, we explored the chemical space in the solvent-exposed region of the enzyme catalytic binding pocket. Extensive structural modifications led to the discovery of a number of heterocycloalkyl esters as potent in vitro PDE4 inhibitors. (S*,S**)-18e and (S*,S**)-22e, in particular, exhibited optimal in vitro ADME and pharmacokinetics properties and dose-dependently counteracted acute lung eosinophilia in an experimental animal model. The optimal biological profile as well as the excellent solid-state properties suggest that both compounds have the potential to be effective topical agents for treating respiratory inflammatory diseases.

Recommendations of the Spanish Society of Rheumatology on treatment and use of systemic biological and non-biological therapies in psoriatic arthritis

OBJECTIVE

The main purpose of this recommendation statement is to provide clinicians with the best available evidence and the best opinion agreed upon by the panelists for a rational use of synthetic disease modifying antirheumatic drugs (DMARDs) and biologicals in psoriatic arthritis (PsA) patients. The present document also focuses on important aspects in the management of PsA, such as early diagnosis, therapeutic objectives, comorbidities and optimization of treatment.

METHODS

The recommendations were agreed by consensus by a panel of 8 expert rheumatologists, previously selected by the Spanish Society of Rheumatology (SER) through an open call. The phases of the work were: identification of key areas for updating the previous consensus, analysis and synthesis of scientific evidence (modified Oxford system, Centre for Evidence-based Medicine, 2009) and formulation of recommendations based on this evidence and by consensus techniques.

RESULTS

Seventeen recommendations were issued for the treatment of PsA patients. Six of them were of general nature, ranging from the early diagnosis and treatment to the importance of assessing comorbidities. The other 11 were focused on the indications for DMARDs and biological therapy in the distinct clinical forms of the disease. Likewise, the situation of failure of the first biological is addressed and treatment algorithms and a table with the different biological therapies are also included.

CONCLUSIONS

We present the update of SER recommendations for the treatment of PsA with DMARDs and biologics.

Signaling Рathway Blockers: Action Mechanism, Efficacy, Safety of Therapy for Patients with Psoriasis and Psoriatic Arthritis

In the literature review, contemporary data on immune pathogenesis of psoriasis and the emergence of comorbid states against the background of systemic chronic inflammation among patients is discussed. On the example of the apremilast medical preparation, the information on a new class of therapeutic agents for the treatment of psoriasis and psoriatic arthritis – “small molecules” is given, including their physicochemical properties and action mechanism, as well as on the key differences from immune-suppressive and genetically engineered biological preparations. Data on large-scale international randomised clinical trials of the efficacy and safety of the PDE4 inhibitor of apremilast among patients with moderate to severe psoriasis and psoriatic arthritis is presented. The published international clinical recommendations on the use of apremilast among patients with psoriasis and psoriatic arthritis, the criteria for evaluating the response to therapy, as well as the potential profile of patients for the use of apremilast in real clinical practice are discussed.

PDE4 Inhibition and Inflammatory Bowel Disease: A Novel Therapeutic Avenue

BACKGROUND

In the last few decades, a better knowledge of the inflammatory pathways involved in the pathogenesis of Inflammatory Bowel Disease (IBD) has promoted biological therapy as an important tool to treat IBD patients. However, in spite of a wider spectrum of biological drugs, a significant proportion of patients is unaffected by or lose their response to these compounds, along with increased risks of infections and malignancies. For these reasons there is an urgent need to look for new pharmacological targets. The novel Phosphodiesterase 4 (PDE4) inhibitors have been recently introduced as new modulators of intracellular signals and gene transcription for the treatment of IBD.

AIM

To discuss and describe the state of the art of this new class of compounds in the IBD field, with particular attention to apremilast.

METHODS

Published articles selected from PubMed were comprehensively reviewed, with key words including apremilast, inflammatory disease, IBD, psoriasis, psoriatic arthritis, pathogenesis, therapies, and treatment.

RESULTS

PDE4 inhibitors generate elevated intracellular levels of cyclic Adenosine Monophosphate (cAMP), that consequently down-regulate the release of pro-inflammatory cytokines in the mucosa of IBD patients. The newly developed apremilast is one of these drugs and has already been approved for the treatment of dermatologic/rheumatologic inflammatory conditions; studies in psoriasis and psoriatic arthritis have in fact demonstrated its clinical activity. However, no clinical trials have yet been published on the use of apremilast in IBD.

CONCLUSION

In light of the similarity of pro-inflammatory signaling pathways across the gut, the skin, and joints, apremilast is likely supposed to show its efficacy also in IBD.

The phosphodiesterase 4 inhibitor apremilast inhibits Th1 but promotes Th17 responses induced by 6-sulfo LacNAc (slan) dendritic cells

BACKGROUND

The phosphodiesterase 4 (PDE4) inhibitor apremilast increases cellular cAMP levels and has proven effective in the treatment of psoriasis and psoriasis arthritis. We recently described 6-sulfo LacNAc dendritic cells (slanDCs) as immature DCs in blood and as a subset of inflammatory dermal DCs in psoriasis with a pronounced capacity to produce proinflammatory cytokines and to program Th17/Th1 T cell responses.

OBJECTIVE

The aim of this study was to investigate possible immune regulatory effects of the PDE4 inhibitor apremilast on slanDCs.

METHODS

In vitro studies were performed analyzing the effects of apremilast on the proinflammatory function of slanDCs and their capacity to induce Th1/Th17-biased T cell responses.

RESULTS

Increasing cAMP levels in slanDCs by PDE4 inhibition strongly reduced production of IL-12 and TNF-α. In line with these findings, co-culture experiments with apremilast-pulsed slanDCs and allogeneic T cells either from psoriasis patients or healthy controls, revealed a significant reduction of IFN-γ production and expression of the transcription factor T-bet. In parallel, production of IL-23 and IL-1ß by slanDCs was increased and co-cultured T cells revealed a largely augmented IL-17 production and an upregulated RORyt expression.

CONCLUSIONS

We here demonstrate anti-inflammatory as well as Th17-promoting effects of apremilast when studying blood precursors of human inflammatory dermal dendritic cells. In the concert of the broad anti-inflammatory effects of apremilast on keratinocytes, fibroblasts and endothelial cells, the dual effect on slan⁺ inflammatory dermal DCs should be taken into account and may constrain therapeutic responses.

Apremilast, an oral phosphodiesterase 4 inhibitor, in the treatment of Japanese patients with moderate to severe plaque psoriasis: Efficacy, safety and tolerability results from a phase 2b randomized controlled trial

Apremilast, an oral, small‐molecule phosphodiesterase 4 inhibitor, works intracellularly within immune cells to regulate inflammatory mediators. This phase 2b randomized, placebo‐controlled study evaluated efficacy and safety of apremilast among Japanese patients with moderate to severe plaque psoriasis. In total, 254 patients were randomized to placebo, apremilast 20 mg b.i.d. (apremilast 20) or apremilast 30 mg b.i.d. (apremilast 30) through week 16; thereafter, all placebo patients were re‐randomized to apremilast 20 or 30 through week 68. Efficacy assessments included achievement of 75% or more reduction from baseline in Psoriasis Area and Severity Index score (PASI‐75; primary) and achievement of static Physician Global Assessment (sPGA; secondary) score of 0 (clear) or 1 (minimal) at week 16. Safety was assessed through week 68. At week 16, PASI‐75 response rates were 7.1% (placebo), 23.5% (apremilast 20; P = 0.0032 vs placebo) and 28.2% (apremilast 30; P = 0.0003 vs placebo); sPGA response rates (score of 0 or 1) were 8.8% (placebo), 23.9% (apremilast 20; P = 0.0165 vs placebo) and 29.6% (apremilast 30; P = 0.0020 vs placebo). Responses were maintained with apremilast through week 68. Most common adverse events (AEs) with placebo, apremilast 20 and apremilast 30 (0–16 weeks) were nasopharyngitis (8.3%, 11.8%, 11.8%), diarrhea (1.2%, 8.2%, 9.4%), and abdominal discomfort (1.2%, 1.2%, 7.1%), respectively. Exposure‐adjusted incidence of these AEs did not increase with continued apremilast treatment (up to 68 weeks). Apremilast demonstrated efficacy and safety in Japanese patients with moderate to severe plaque psoriasis through 68 weeks that was generally consistent with prior studies.

Beyond TNF Inhibitors: New Pathways and Emerging Treatments for Psoriatic Arthritis

Psoriatic arthritis (PsA) is a chronic inflammatory disease characterized by psoriasis, synovitis, enthesitis, spondylitis and association with other extra-articular manifestations. Chronic inflammation of involved tissues possibly leads to structural damage and to a reduction in function and quality of life. The treatment of PsA dramatically changed with the introduction of anti-tumor necrosis factor (TNF)-α drugs, which have been shown to reduce the symptoms and signs of the disease, and slow radiographic progression. However, some patients do not respond to anti-TNFα or have a loss of response. Recently, the discovery of new pathogenic mechanisms have made possible the development of new drugs that target pro-inflammatory cytokines, such as interleukin (IL)-12, IL-23 and IL-17, or interfere with cellular pathways involved in skin, joint and entheseal inflammation. New molecules, namely ustekinumab, secukinumab, and apremilast have shown efficacy and safety over the various components of the disease in randomized clinical trials. These drugs have been recently approved for the treatment of PsA and included in new treatment recommendations. Other molecules are currently being tested in phase III clinical trials and are potential new treatment options for PsA. The aim of this review is to update the new pathways involved in the development of the disease and the emerging treatments for PsA beyond TNFα inhibition.

A new therapeutic for the treatment of moderate-to-severe plaque psoriasis: apremilast

Psoriasis is a common, chronic, inflammatory skin disease. Being a life-long condition, a prolonged and safe control of the disease is needed. Current anti-psoriatic treatments show some limits in terms of tolerability and route of administration. Recently, a new oral small molecule, apremilast, has been approved for the treatment of patients with moderate-to-severe plaque psoriasis. Apremilast is a phosphodiesterase 4 (PDE4) inhibitor that regulates the transduction of intracellular signals, including pro-inflammatory and anti-inflammatory pathways. Because of the favorable safety profile and the oral route of administration, apremilast may represent a promising therapeutic target for moderate-to-severe psoriasis. In this review, we report an updated overview about clinical trials testing apremilast in the treatment of psoriasis and seek to provide comprehensive information about this anti-psoriatic drug and a future perspective of the therapeutic algorithm for psoriasis.

Selective intracellular inhibition of signalling pathways - new direction in systematic treatment of psoriasis patients

This article presents current data from publications on new direction in systematic treatment of patients with psoriasis with help of "small molecules" that act intracellularly, selectively inhibiting signaling pathways responsible for production of key pro- and anti-inflammatory mediators that play an important role in the pathophysiology of psoriasis. We discuss key issues that refer to immunopathogenesis of psoriasis, targeted influence of "small molecules" on key components of innate and adaptive immune system of patients psoriasis. This article presents results of the studies performed according to the evidence-based medicine approaches, on the efficiency and safety of apremilast - the first and only current selective inhibitor of intracellular phosphodiesterase 4 - for treating medium-severe and severe psoriasis, including patients with problematic localizations of dermatosis (psoriasis of scalp pilar part, palms, soles, nail plates), as well as in the long run. It is shown that continuous apremilast therapy for the term of 52-156 weeks was accompanied by a significant decrease in prevalence and severity of psoriasis. Adverse events were recorded rarely, they were mild, and frequency of serious adverse reactions was comparable to placebo.

In vivo effective dibenzo[b,d]furan-1-yl-thiazoles as novel PDE-4 inhibitors

Herein we report the synthesis, PDE-4B and TNF-α inhibitory activities of a few dibenzo[b,d]furan-1-yl-thiazole derivatives. The hydroxycyclohexanol amide derivatives 14, 18, 24, 29, 31 and 33 exhibited promising in vitro PDE-4B and TNF-α inhibitory activities. Compound 24 showed good systemic availability in preclinical animal models and was also found to be non-toxic (exploratory mutagenicity test). Further it exhibited promising results in in vivo asthma/COPD and Uveitis models.

Oral Apremilast for the Treatment of Plaque Psoriasis

This article provides an update on the use of oral apremilast, a phosphodiesterase-4 (PDE4) inhibitor, for the treatment of plaque psoriasis. Emphasis is placed on safety evaluations, although efficacy considerations are also addressed. Both two-year and three -year data analyses support the favorable safety profile reported in pivotal trials with this agent. Although effective in many study subjects despite baseline characteristics, higher response rates were noted in those with a baseline psoriasis area and severity index (PASI) score <20 and in subjects not previously treated with systemic therapy for psoriasis. Gastrointestinal (GI) side effects are the most common adverse events (AEs) reported, especially during the first few weeks of use; recommendations on management of GI AEs are discussed. Psychological AEs appear to be rare, including with prolonged durations of use, and are not clearly associated with the drug itself as depression and suicidal behaviors are common in individuals with psoriasis. Data reported through up to 182 weeks of exposure to apremilast do not support an association with cardiac AEs, emergence of malignancies, enhanced predilection to develop significant opportunistic infections, or reactivation of occult infection, such as tuberculosis.

The effects of apremilast on the QTc interval in healthy male volunteers: a formal, thorough QT study

OBJECTIVE

This study was conducted to evaluate the effect of apremilast and its major metabolites on the placebocorrected change-from-baseline QTc interval of an electrocardiogram (ECG).

MATERIALS AND METHODS

Healthy male subjects received each of 4 treatments in a randomized, crossover manner. In the 2 active treatment periods, apremilast 30 mg (therapeutic exposure) or 50 mg (supratherapeutic exposure) was administered twice daily for 9 doses. A placebo control was used to ensure doubleblind treatment of apremilast, and an openlabel, single dose of moxifloxacin 400 mg was administered as a positive control. ECGs were measured using 24-hour digital Holter monitoring.

RESULTS

The two-sided 98% confidence intervals (CIs) for ΔΔQTcI of moxifloxacin completely exceeded 5 ms 2 - 4 hours postdose. For both apremilast dose studies, the least-squares mean ΔΔQTcI was < 1 ms at all time points, and the upper limit of two-sided 90% CIs was < 10 ms. There were no QT/QTc values > 480 ms or a change from baseline > 60 ms. Exploratory evaluation of pharmacokinetic/pharmacodynamic data showed no trend between the changes in QT/QTc interval and the concentration of apremilast or its major metabolites M12 and M14.

CONCLUSIONS

Apremilast did not prolong the QT interval and appears to be safe and well tolerated up to doses of 50 mg twice daily.

[Guidelines for vaccination of immunocompromised individuals]

Immunosuppression of various origins is associated with an increased risk of infection; therefore the prevention of infectious diseases by vaccination is especially important in immunocompromised patients. However, the response to vaccinations is often reduced in these risk groups and the application of live vaccines is contraindicated during immunosuppression.In the following expert statement, recommendations for vaccination were created on the basis of current evidence and theoretical/immunological considerations. A first, general part elaborates on efficacy and safety of vaccinations during immunosuppression, modes of action of immunosuppressive medications and recommended time intervals between immunosuppressive treatments and vaccinations. A core piece of this part is a graduation of immunosuppression into three stages, i. e. no relevant immunosuppression, mild to moderate and severe immunosuppression and the assignment of various medications (including biologicals) to one of those stages; this is followed by an overview of possible and necessary vaccinations in each of those stages.The second part gives detailed vaccination guidelines for common diseases and therapies associated with immunosuppression. Primary immune deficiencies, chronic kidney disease, diabetes mellitus, solid and hematological tumors, hematopoetic stem cell transplantation, transplantation of solid organs, aspenia, rheumatological-, gastroenterologic-, dermatologic-, neurologic diseases, biologicals during pregnancy and HIV infection are dealt with.These vaccination guidelines, compiled for the first time in Austria, aim to be of practical help for physicians to facilitate and improve vaccination coverage in immunocompromised patients and their household members and contact persons.

Pharmacodynamic assessment of apremilast for the treatment of moderate-to-severe plaque psoriasis

INTRODUCTION

Psoriasis is a chronic inflammatory skin disease affecting 2-3% of the population. Certain systemic drugs currently available for its treatment could be associated, in the long term, with organ toxicity and adverse events, thus, clinical monitoring throughout treatment is required. Moreover, tolerability issues, parenteral administration, and barriers to patient access, such as high cost and specialist management lead to treatment failure.

AREAS COVERED

Apremilast is an oral small molecule inhibitor of phosphodiesterase 4 (PDE4i). PDE is the major enzyme class responsible for the hydrolysis of cyclic adenosine monophosphate in immune cells (cAMP). With PDE4 inhibition, apremilast works intracellularly to modulate pro-inflammatory and anti-inflammatory mediator production critically involved in psoriasis. The aim of this paper is to focus the attention on apremilast pharmacodynamics effects, its efficacy and safety in treating moderate-to-severe plaque psoriasis.

EXPERT OPINION

Apremilast is an effective and well-tolerated option in treating moderate-to-severe plaque psoriasis. Its safety profile and the oral administration offer significant advantages in prescribing apremilast for the treatment of psoriasis, particularly in some subsets of patients.

Determination of apremilast in rat plasma by UPLC–MS/MS in ESI-negative mode to avoid adduct ions formation

Background: Quantification of target analyte by LC–MS/MS is sometimes hampering due to competitive adduct ions formation (sodium and/or ammonium) in positive ionization mode. A UPLC–MS/MS assay was developed for the determination of apremilast in rat plasma using ESI-negative mode to avoid adduct ions formation. Method & results: After extraction from plasma by ethyl acetate, analyte and IS were separated on Aquity BEH C18 column using acetonitrile-10 mM ammonium acetate (85:15) as mobile phase. The calibration curve was linear between 3.04 and 1000 ng/ml with correlation coefficients (r2) of ≥0.995 and lower limit of quantification of 3.04 ng/ml. All validation parameter results were within the acceptable range. The assay was successfully employed in oral PK study with Cmax of 584.29 ng/ml and AUC0–20 of 6530 ng.h/ml after apremilast (2 mg/kg) administration. Conclusion: This result suggests that ESI in negative mode would be an alternative approach for LC–MS/MS quantification of analytes, which produce competitive adducts in positive mode.

Considerations for the Conduct of Clinical Trials with Antiinflammatory Agents in Cystic Fibrosis. A Cystic Fibrosis Foundation Workshop Report

Inflammation leads to lung destruction and loss of pulmonary function in patients with cystic fibrosis (CF). Drugs that modulate the cystic fibrosis transmembrane conductance regulator (CFTR) have recently been approved. Although the impact of CFTR modulators on sweat chloride and lung function are exciting, they have not yet demonstrated an effect on inflammation. Therefore, CF antiinflammatory drug development must continue. Unfortunately, the lack of clarity with this process has left investigators and industry sponsors frustrated. The Cystic Fibrosis Foundation established a working group in early 2014 to address this issue. There are many inflammatory processes disrupted in CF, and, therefore, there are many potential targets amenable to antiinflammatory therapy. Regardless of a drug's specific mechanism of action, it must ultimately affect the neutrophil or its products to impact CF. The working group concluded that before bringing new antiinflammatory drugs to clinical trial, preclinical safety studies must be conducted in disease-relevant models to assuage safety concerns. Furthermore, although studies of antiinflammatory therapies must first establish safety in adults, subsequent studies must involve children, as they are most likely to reap the most benefit. The working group also recommended that pharmacokinetic-pharmacodynamic studies and early-phase safety studies be performed before proceeding to larger studies of longer duration. In addition, innovative study designs may improve the likelihood of adequately assessing treatment response and mitigating risk before conducting multiyear studies. Learning from past experiences and incorporating this knowledge into new drug development programs will be instrumental in bringing new antiinflammatory therapies to patients.

The cAMP Pathway as Therapeutic Target in Autoimmune and Inflammatory Diseases

Nucleotide signaling molecules contribute to the regulation of cellular pathways. In the immune system, cyclic adenosine monophosphate (cAMP) is well established as a potent regulator of innate and adaptive immune cell functions. Therapeutic strategies to interrupt or enhance cAMP generation or effects have immunoregulatory potential in autoimmune and inflammatory disorders. Here, we provide an overview of the cyclic AMP axis and its role as a regulator of immune functions and discuss the clinical and translational relevance of interventions with these processes.