Apremilast, a cAMP phosphodiesterase-4 inhibitor, demonstrates anti-inflammatory activity in vitro and in a model of psoriasis

An Overview of PDE4 Inhibitors in Clinical Trials: 2010 to Early 2022

Since the early 1980s, phosphodiesterase 4 (PDE4) has been an attractive target for the treatment of inflammation-based diseases. Several scientific advancements, by both academia and pharmaceutical companies, have enabled the identification of many synthetic ligands for this target, along with the acquisition of precise information on biological requirements and linked therapeutic opportunities. The transition from pre-clinical to clinical phase was not easy for the majority of these compounds, mainly due to their significant side effects, and it took almost thirty years for a PDE4 inhibitor to become a drug i.e., Roflumilast, used in the clinics for the treatment of chronic obstructive pulmonary disease. Since then, three additional compounds have reached the market a few years later: Crisaborole for atopic dermatitis, Apremilast for psoriatic arthritis and Ibudilast for Krabbe disease. The aim of this review is to provide an overview of the compounds that have reached clinical trials in the last ten years, with a focus on those most recently developed for respiratory, skin and neurological disorders.

More than a random association between chronic obstructive pulmonary disease and psoriatic arthritis: shared pathogenic features and implications for treatment

INTRODUCTION

Psoriatic arthritis (PsA) is a chronic inflammatory condition characterized by skin and joints involvement, and with a great burden of comorbidity that could affect the choice of treatment. Chronic obstructive pulmonary disease (COPD) is one of the primary causes of morbidity and mortality. Medical therapy can improve symptoms and the frequency and severity of exacerbations. A variety of evidence showed an increasing association between COPD and PsA.

AREAS COVERED

Psoriatic disease and COPD appear to have a possible pathophysiologic link. The inhibition of intracellular molecules responsible for pro-inflammatory responses could be a therapeutic approach for both psoriatic diseases and COPD. Inhibitors of phosphodiesterase 4 (PDE-4) were developed to treat chronic inflammatory conditions such as psoriasis, PsA and COPD. Roflumilast has been used to treat COPD and asthma, while Apremilast to treat psoriasis and PsA. Given the efficacy and safety of these treatments, we can speculate that blocking PDE-4 might also provide clinical benefits in patients with co-existing COPD and PsA.

EXPERT OPINION

This hypothesis could offer the opportunity to screen patients for both diseases. Furthermore, this approach would increase the involvement of other specialists in the management of PsA, and it would improve the use of a tailored treatment for each patient.

Regulatory T Cells: Therapeutic Opportunities in Uveitis

Regulatory T cells (Tregs) are critical for the maintenance of immune tolerance and the suppression of excessive inflammation. Many inflammatory autoimmune disorders, including autoimmune uveitis, involve the loss of the suppressive capacities of Tregs. Over the past decade, Tregs' therapeutic potential in uveitis has garnered increasing attention. Specific subsets of Tregs, including TIGIT+ and PD-1+ Tregs, have emerged as potent immunosuppressors that may be particularly well-suited to cell-based therapeutics. Studies have elucidated the interaction between Treg development and the gut microbiome as well as various intracellular signaling pathways. Numerous cell-based therapies and therapeutic molecules have been proposed and investigated using the murine experimental autoimmune uveitis (EAU) model. However, certain challenges remain to be addressed. Studies involving the use of Tregs in human patients with uveitis are lacking, and there are concerns regarding Tregs' production and purification for practical use, their plasticity towards inflammatory phenotypes, immunogenicity, and tumorigenicity. Nevertheless, recent research has brought Tregs closer to yielding viable treatment options for uveitis.

The Evolving Landscape of Cutaneous Sarcoidosis: Pathogenic Insight, Clinical Challenges, and New Frontiers in Therapy

Sarcoidosis is a multisystem disorder of unknown etiology characterized by accumulation of granulomas in affected tissue. Cutaneous manifestations are among the most common extrapulmonary manifestations in sarcoidosis and can lead to disfiguring disease requiring chronic therapy. In many patients, skin disease may be the first recognized manifestation of sarcoidosis, necessitating a thorough evaluation for systemic involvement. Although the precise etiology of sarcoidosis and the pathogenic mechanisms leading to granuloma formation, persistence, or resolution remain unclear, recent research has led to significant advances in our understanding of this disease. This article reviews recent advances in epidemiology, sarcoidosis clinical assessment with a focus on the dermatologist's role, disease pathogenesis, and new therapies in use and under investigation for cutaneous and systemic sarcoidosis.

Discovery and Structural Optimization of Toddacoumalone Derivatives as Novel PDE4 Inhibitors for the Topical Treatment of Psoriasis

Psoriasis is a common immune-mediated skin disorder manifesting in abnormal skin plaques, and phosphodiesterase 4 (PDE4) is an effective target for the treatment of inflammatory diseases such as psoriasis. Toddacoumalone is a natural PDE4 inhibitor with moderate potency and imperfect drug-like properties. To discover novel and potent PDE4 inhibitors with considerable druggability, a series of toddacoumalone derivatives were designed and synthesized, leading to the compound (2R,4S)-6-ethyl-2-(2-hydroxyethyl)-2,8-dimethyl-4-(2-methylprop-1-en-1-yl)-2,3,4,6-tetrahydro-5H-pyrano[3,2-c][1,8]naphthyridin-5-one (33a) with high inhibitory potency (IC₅₀ = 3.1 nM), satisfactory selectivity, favorable skin permeability, and a well-characterized binding mechanism. Encouragingly, topical administration of 33a exhibited remarkable therapeutic effects in an imiquimod-induced psoriasis mouse model.

Inhibition of PDE4 by apremilast attenuates skin fibrosis through directly suppressing activation of M1 and T cells

Systemic sclerosis (SSc) is a life-threatening chronic connective tissue disease with the characteristics of skin fibrosis, vascular injury, and inflammatory infiltrations. Though inhibition of phosphodiesterase 4 (PDE4) has been turned out to be an effective strategy in suppressing inflammation through promoting the accumulation of intracellular cyclic adenosine monophosphate (cAMP), little is known about the functional modes of inhibiting PDE4 by apremilast on the process of SSc. The present research aimed to investigate the therapeutic effects and underlying mechanism of apremilast on SSc. Herein, we found that apremilast could markedly ameliorate the pathological manifestations of SSc, including skin dermal thickness, deposition of collagens, and increased expression of α-SMA. Further study demonstrated that apremilast suppressed the recruitment and activation of macrophages and T cells, along with the secretion of inflammatory cytokines, which accounted for the effects of apremilast on modulating the pro-fibrotic processes. Interestingly, apremilast could dose-dependently inhibit the activation of M1 and T cells in vitro through promoting the phosphorylation of CREB. In summary, our research suggested that inhibiting PDE4 by apremilast might provide a novel therapeutic option for clinical treatment of SSc patients.

Apremilast Improves Endothelial Glycocalyx Integrity, Vascular and Left Ventricular Myocardial Function in Psoriasis

The phosphodiesterase 4 inhibitor apremilast is used for the treatment of psoriasis. We investigated the effects of apremilast on endothelial glycocalyx, vascular and left ventricular (LV) myocardial function in psoriasis. One hundred and fifty psoriatic patients were randomized to apremilast (n = 50), anti-tumor necrosis factor-α (etanercept; n = 50), or cyclosporine (n = 50). At baseline and 4 months post-treatment, we measured: (1) Perfused boundary region (PBR), a marker of glycocalyx integrity, in sublingual microvessels with diameter 5–25 μm using a Sidestream Dark Field camera (GlycoCheck). Increased PBR indicates damaged glycocalyx. Functional microvascular density, an index of microvascular perfusion, was also measured. (2) Pulse wave velocity (PWV-Complior) and (3) LV global longitudinal strain (GLS) using speckle-tracking echocardiography. Compared with baseline, PBR5–25 μm decreased only after apremilast (−12% at 4 months, p < 0.05) whereas no significant changes in PBR5–25 μm were observed after etanercept or cyclosporine treatment. Compared with etanercept and cyclosporine, apremilast resulted in a greater increase of functional microvascular density (+14% versus +1% versus −1%) and in a higher reduction of PWV. Apremilast showed a greater increase of GLS (+13.5% versus +7% versus +2%) than etanercept and cyclosporine (p < 0.05). In conclusion, apremilast restores glycocalyx integrity and confers a greater improvement of vascular and myocardial function compared with etanercept or cyclosporine after 4 months.

Antirheumatic Drugs against COVID-19 from the Perspective of Rheumatologists

Coronavirus disease 2019 (COVID-19) remains a global threat to humanity. Its pathogenesis and different phases of disease progression are being elucidated under the pandemic. Active viral replication activates various immune cells and produces large amounts of inflammatory cytokines, which leads to the cytokine storm, a major cause of patient death. Therefore, viral inhibition is expected to be the most effective early in the course of the disease, while immunosuppressive treatment may be useful in the later stages to prevent disease progression. Based on the pathophysiology of rheumatic diseases, various immunomodulatory and immunosuppressive drugs are used for the diseases. Due to their mechanism of action, the antirheumatic drugs, including hydroxychloroquine, chloroquine, colchicine, calcineurin inhibitors (e.g., cyclosporine A and tacrolimus), glucocorticoids, cytokines inhibitors, such as anti-tumor necrosis factor-α (e.g., infliximab), anti-interleukin (IL)-6 (e.g., tocilizumab, sarilumab, and siltuximab), anti-IL-1 (e.g., anakinra and canakinumab) and Janus kinase inhibitors (e.g., baricitinib and tofacitinib), cytotoxic T lymphocyte-associated antigen 4 blockade agents (e.g., abatacept), and phosphodiesterase 4 inhibitors (e.g., apremilast), have been tried as a treatment for COVID-19. In this review, we discuss the mechanisms of action and clinical impact of these agents in the management of COVID-19.

Effects of Apremilast on Induced Hypertrophic Scar of Rabbits

The present study aimed to assess the effect of Apremilast on experimentally induced hypertrophic scars in rabbits. A total of 40 healthy male New Zealand White rabbits between 6 and 12 months of age were assigned to four groups (n=10). Group I consists of apparently healthy control rabbits, in group II, the rabbits with an induced hypertrophic scar received no treatment, except for base gel. In group III, the rabbits with induced hypertrophic scar were treated with triamcinolone acetonide (TAC) 0.1% as standard medication. In group IV, rabbits with induced hypertrophic scars were treated with Apremilast 5%. On the first day, four surgical incisions were made using an 8-mm biopsy punch on the ventral surface of the rabbit ear down to cartilage. The TAC and Apremilast were topically administered to the developed scars on day 31. The results included an examination of skin histopathology, the level of transforming growth factor beta-1 (TGF-β1), and collagen III in skin tissue. In the treatments, the inflammatory score, scar index, as well as immunological scores of TGFβ1 and collagen III, significantly decreased, compared to the hypertrophic induced scar group (P≤ 0.001). Moreover, there was a significant reduction in fibroblast count, compared to the group of induced hypertrophic scars (P<0.05). Apremilast was efficacious in the treatment of hypertrophic scars due to its ability to reduce inflammations and fibroblast counts and scar index. Nonetheless, the reduction of immunological scores was almost comparable to that of topical TAC.

Phosphodiesterase-4 Inhibition Reduces Cutaneous Inflammation and IL-1β Expression in a Psoriasiform Mouse Model but Does Not Inhibit Inflammasome Activation

Apremilast (Otezla^®) is an oral small molecule phosphodiesterase 4 (PDE4) inhibitor approved for the treatment of psoriasis, psoriatic arthritis, and oral ulcers associated with Behçet’s disease. While PDE4 inhibition overall is mechanistically understood, the effect of apremilast on the innate immune response, particularly inflammasome activation, remains unknown. Here, we assessed the effect of apremilast in a psoriasis mouse model and primary human cells. Psoriatic lesion development in vivo was studied in K5.Stat3C transgenic mice treated with apremilast for 2 weeks, resulting in a moderate (2 mg/kg/day) to significant (6 mg/kg/day) resolution of inflamed plaques after 2-week treatment. Concomitantly, epidermal thickness dramatically decreased, the cutaneous immune cell infiltrate was reduced, and proinflammatory cytokines were significantly downregulated. Additionally, apremilast significantly inhibited lipopolysaccharide- or anti-CD3-induced expression of proinflammatory cytokines in peripheral mononuclear cells (PBMCs). Notably, inflammasome activation and secretion of IL-1β were not inhibited by apremilast in PBMCs and in human primary keratinocytes. Collectively, apremilast effectively alleviated the psoriatic phenotype of K5.Stat3 transgenic mice, further substantiating PDE4 inhibitor-efficiency in targeting key clinical, histopathological and inflammatory features of psoriasis. Despite lacking direct effect on inflammasome activation, reduced priming of inflammasome components upon apremilast treatment reflected the indirect benefit of PDE4 inhibition in reducing inflammation.

Apremilast effectively inhibits TNFα-induced vascular inflammation in human endothelial cells

BACKGROUND

Patients with chronic inflammatory diseases (e.g. psoriasis and rheumatoid arthritis) are at increased risk for the development of atherosclerosis and cardiovascular diseases (CVD). Previous studies have suggested that phosphodiesterase 4 (PDE4) inhibitors possess anti-inflammatory properties.

OBJECTIVES

Here we examined the effect of the PDE4 inhibitor apremilast, a well-established anti-psoriatic drug, on pro-inflammatory responses in TNFα-activated endothelial cells.

METHODS

Human umbilical vein endothelial cells (HUVEC) were treated with tumour necrosis factor-α (TNFα) in the presence or absence of apremilast. Expression levels of pro-inflammatory cytokines, chemokines and adhesion molecules were assessed by ELISA, western blot and RT-PCR. Effects of apremilast on adhesion and transendothelial migration (TEM) of THP-1 monocytic cells were analysed in transwell assays.

RESULTS

Apremilast suppressed TNFα-induced expression and secretion of important endothelial and monocytic pro-inflammatory factors, including granulocyte-macrophage colony-stimulating factor (GM-CSF), C-X-C motif chemokine ligand 10 (CXCL10), chemokine (C-C motif) ligand 2 (CCL2), vascular cell adhesion molecule 1 (VCAM-1), E-selectin and matrix metalloproteinase-9 (MMP9). Functionally, apremilast reduced adhesion of THP-1 cells to activated HUVECs and TEM in response to TNFα. Mechanistically, apremilast suppressed activation of nuclear factor κB (NFκB) and mitogen-activated protein kinases (MAPK) signalling in activated HUVECs. Furthermore, inhibition of p38, C-Jun-N-terminale Kinase (JNK) and NFκB in activated HUVECs decreased expression of GM-CSF, VCAM-1 and E-selectin. Additionally, apremilast decreased IL-17A-induced secretion of IL-6 and CCL2.

CONCLUSIONS

We demonstrate that apremilast has distinct anti-inflammatory effects in activated HUVECs, indicating that apremilast could have the therapeutic potential to prevent higher risk for CVD in patients with chronic inflammatory diseases.

Immune treatments for alcohol use disorder: A translational framework

While the immune system is essential for survival, an excessive or prolonged inflammatory response, such as that resulting from sustained heavy alcohol use, can damage the host and contribute to psychiatric disorders. A growing body of literature indicates that the immune system plays a critical role in the development and maintenance of alcohol use disorder (AUD). As such, there is enthusiasm for treatments that can restore healthy levels of inflammation as a mechanism to reduce drinking and promote recovery. In this qualitative literature review, we provide a conceptual rationale for immune therapies and discuss progress in medications development for AUD focused on the immune system as a treatment target. This review is organized into sections based on primary signaling pathways targeted by the candidate therapies, namely: (a) toll-like receptors, (b) phosphodiesterase inhibitors, (c) peroxisome proliferator-activated receptors, (d) microglia and astrocytes, (e) other immune pharmacotherapies, and (f) behavioral therapies. As relevant within each section, we examine the basic biological mechanisms of each class of therapy and evaluate preclinical research testing the role of the therapy on mitigating alcohol-related behaviors in animal models. To the extent available, translational findings are reviewed with discussion of completed and ongoing randomized clinical trials and their findings to date. An applied and clinically focused approach is taken to identify the potential clinical applications of the various treatments reviewed. We conclude by delineating the most promising candidate treatments and discussing future directions by considering opportunities for immune treatment development and personalized medicine for AUD.

Systematic thermodynamic analysis of apremilast polymorphs via solubility measurement with modeling: Mechanism evaluation through molecular simulation

The polymorphism of apremilast has been investigated. Two polymorphs have been identified and characterized by differential scanning calorimeter, fourier transform infrared spectroscopy, and powder X-ray diffractometer. Solubilities of apremilast forms B and E in three binary solvents of methanol-water, acetonitrile-water, and acetonitrile-methanol have been measured using the static method at a temperature ranging from 288.15 K to 328.15 K under standard atmospheric pressure. Subsequently, the solubility data have been analyzed using the Wilson, NRTL, and UNIQUAC thermodynamic models, respectively. Furthermore, the Gibbs energy of solution and the radial distribution function have been calculated using the molecular simulation method to evaluate the dissolution mechanism. The Gibbs energy of solution reveals that the rank of solute-solvent interaction correlated well with solubility order in binary solvent mixtures, and the radial distribution function indicates that weakening of solvent-solvent interaction led to an increase in solubility.

Two cases of Hailey-Hailey disease effectively treated with apremilast and a review of reported cases

Hailey-Hailey disease (HHD) is an autosomal dominant genetic disease caused by a mutation of the ATP2C1 gene. Corticosteroids, antibiotics or cyclosporine have been administered to reduce inflammation and prevent flare-ups, but the efficacy is not always sufficient. We herein report two cases of HHD effectively treated with apremilast and review the previous literature. Patient 1 was a 28-year-old male and patient 2 was a 35-year-old female. Both patients were diagnosed with HHD based on histological and genetic analyses. Both patients were treated with oral antibiotics or topical corticosteroids, but their symptoms were refractory, therefore apremilast was administered to both patients. Two weeks later, the skin lesion of both patients was improved. No adverse reaction was observed except for mild headache in patient 2. There have been 13 reported cases of HHD treated with apremilast, including our cases. Eight cases showed a good response to apremilast, whereas five cases showed no response. There seems to be no association between the disease severity and efficacy of apremilast, although the reason remains unknown. Interestingly, an early improvement of the HHD lesion was observed in all good response cases. Although digestive symptoms, headache, and myalgia were observed as adverse events, the treatment was well-tolerated. The accumulation of a greater number of similar cases and further research will be required. We hypothesize that apremilast may be a useful therapeutic option for skin lesions of HHD.

Insights into the Pathogenesis of HS and Therapeutical Approaches

Hidradenitis suppurativa (HS) is a debilitating, chronic, (auto)inflammatory disease primarily affecting apocrine gland-rich areas of the body. Although pathogenic mechanisms responsible for HS have not yet been fully elucidated, it is a multifactorial process whose main target is the terminal follicle. The role of the inflammatory process (and consequently of cytokine milieu) and of several other factors (genetics, lifestyle, hormonal status, microbiome, innate and adaptive immune systems) involved in HS pathogenesis has been investigated (and often defined) over the years with a view to transferring research results from bench to bedside and describing a unique and universally accepted pathogenetic model. This review will update readers on recent advances in our understanding of HS pathogenesis and novel (potential) medical therapies for patients with moderate-to-severe HS.

Establishment of an Intradermal Ear Injection Model of IL-17A and IL-36γ as a Tool to Investigate the Psoriatic Cytokine Network

Psoriasis is a chronic skin disease affecting 2–3% of the global population. The proinflammatory IL-17A is a key cytokine in psoriasis. Accumulating evidence has revealed that IL-36γ plays also a pathogenic role. To understand more precisely the role of the IL-17A–IL-36γ cytokine network in skin pathology, we used an ear injection model. We injected IL-17A or IL-36γ alone and in combination into the ear pinnae of mice. This resulted in a significant increase in ear thickness measured over time. Histological evaluation of IL-17A + IL-36γ-treated skin showed a strong acanthosis, hyperparakeratosis and infiltration of neutrophils. The same histological features were found in mice after injection of IL-36γ alone, but to a lesser extent. IL-17A alone was not able to induce psoriasis-like changes. Genes encoding proteins of the S100 family, antimicrobial peptides and chemo-attractants for neutrophils were upregulated in the IL-17A + IL-36γ group. A much weaker expression was seen after the injection of each cytokine alone. These results strengthen the hypothesis that IL-17A and IL-36γ drive psoriatic inflammation via a synergistic interaction. Our established intradermal ear injection model can be utilized in the future to monitor effects of various inhibitors of this cytokine network.

Apremilast in a Japanese subgroup with Behçet's syndrome: Results from a Phase 3, randomised, double-blind, placebo-controlled study

OBJECTIVES

Apremilast efficacy and safety was assessed in a prespecified subgroup of Japanese patients with oral ulcers associated with Behçet's syndrome from a Phase 3 randomized, placebo-controlled, double-blind study of apremilast (RELIEF).

METHODS

The primary end point was area under the curve for number of oral ulcers during the 12-week placebo-controlled phase (AUCWk0-12). Key secondary end points were change from baseline in oral ulcer pain, complete oral ulcer resolution, and measures of disease activity and quality of life (QoL).

RESULTS

Thirty-nine Japanese patients were randomised (apremilast 30 mg BID: n = 19; placebo: n = 20). Improvements at Week 12 were observed for apremilast vs. placebo in AUCWk0-12 for the number of oral ulcers (115.9 vs. 253.3; nominal P = 0.0168); 57.9% vs. 25.0% achieved complete oral ulcer resolution, 47.4% vs. 0.0% achieved oral ulcer resolution by Week 6 and maintained oral ulcer-free status for ≥6 additional weeks; mean change from baseline in BSAS was -10.5 vs. 0.5. Favourable effects were observed for apremilast vs. placebo in other secondary end points, including QoL. Clinical benefits were sustained over 28 weeks of continued apremilast treatment. Adverse events were consistent with apremilast's known safety profile.

CONCLUSIONS

Apremilast reduced the number of oral ulcers and overall disease activity in this Japanese subgroup with Behçet's syndrome.

The Role of Chemokines in Psoriasis-An Overview

By participating in both the recruitment and activation of T lymphocytes, macrophages and neutrophils at the site of psoriatic inflammation, chemokines play an important role in the pathogenesis of psoriasis and, crucially, may be one indicator of the response to the systemic treatment of the disease. As a result of their major involvement in both physiological and pathological processes, both chemokines and their receptors have been identified as possible therapeutic targets. Due to their presence in the inflammatory process, they play a role in the pathogenesis of diseases that often coexist with psoriasis, such as atherosclerosis and psoriatic arthritis. Chemokines, cytokines and adhesion molecules may be biological markers of disease severity in psoriasis. However, the mechanism of inflammation in psoriasis is too complex to select only one marker to monitor the disease process and improvement after treatment. The aim of this review was to summarize previous reports on the role of chemokines in the pathogenesis of psoriasis, its treatment and comorbidities.

Anti-inflammatory effects of a novel phosphodiesterase-4 inhibitor, AA6216, in mouse dermatitis models

Atopic dermatitis (AD) is a chronic inflammatory skin disease that is commonly treated with corticosteroids. However, these drugs have long-term adverse effects, representing an unmet need for new treatments. AD is associated with dysregulation of phosphodiesterase 4 (PDE4) activity in inflammatory cells and the topical PDE4 inhibitor, crisaborole, is approved by the US FDA for mild-to-moderate AD. In this study, we compared the effects of a novel PDE4 inhibitor, AA6216, with those of crisaborole on skin inflammation. We found that AA6216 is a more potent inhibitor of PDE4 and of cytokine production (TNF-α, IL-12/23p40, IL-4, IL-13, and IFN-γ) by human peripheral blood mononuclear cells (PBMCs) stimulated by phytohemagglutinin (PHA) or anti-CD3 antibodies, with IC₅₀ values ranging from 5.9 to 47 nM. AA6216 also significantly suppressed skin inflammation in three mouse models of dermatitis. In acute and chronic oxazolone-induced dermatitis models, topical AA6216 exhibited stronger inhibitory effects on ear inflammation and cytokine production (TNFα, IL-1β, and IL-4) in skin lesions compared with crisaborole. In a Dermatophagoides farinae-induced dermatitis model, AA6216 significantly reduced the dermatitis score, based on the development of erythema/hemorrhage, scarring/dryness, edema, and excoriation/erosion, compared with a clinically used topical AD drug, tacrolimus. These results suggest the possibility that AA6216 is a novel and effective topical therapeutic agent for the treatment of dermatitis including AD.

Emerging Pathophysiological Targets of Psoriasis for Future Therapeutic Strategies

Psoriasis is a chronic autoimmune skin disorder which involves complex interactions between genes, keratinocytes, T-cells and inflammatory cells. It affects 2-3% population worldwide. Molecular biology and cellular immunology of psoriasis, when linked with biotechnology and genetic studies can help researchers to understand the pathophysiology of psoriasis. T-cells activation, keratinocyte hyperproliferation, and angiogenesis are the core mechanisms entailed in the development of psoriasis lesion. Investigators are trying to overcome the challenges of complex pathophysiology pathways involved in this disorder. The different possible hypotheses for its pathophysiology such as growth factors, enzymes, inflammation, and genetic factors mediated pathophysiology have been described in the present review paper in detail. Clinically available drugs only control the symptoms of psoriasis but are not effective for the treatment of the disorder completely and are also associated with some side effects such as itching, renal disorders, hematologic, nonmelanoma skin cancer, pulmonary, gastrointestinal toxicity, etc. This paper made an effort to understand the pathophysiological targets, discuss the research done so far and the treatments available for the effective management of psoriasis.

Development of Phosphodiesterase-Protein-Kinase Complexes as Novel Targets for Discovery of Inhibitors with Enhanced Specificity

Phosphodiesterases (PDEs) hydrolyze cyclic nucleotides to modulate multiple signaling events in cells. PDEs are recognized to actively associate with cyclic nucleotide receptors (protein kinases, PKs) in larger macromolecular assemblies referred to as signalosomes. Complexation of PDEs with PKs generates an expanded active site that enhances PDE activity. This facilitates signalosome-associated PDEs to preferentially catalyze active hydrolysis of cyclic nucleotides bound to PKs and aid in signal termination. PDEs are important drug targets, and current strategies for inhibitor discovery are based entirely on targeting conserved PDE catalytic domains. This often results in inhibitors with cross-reactivity amongst closely related PDEs and attendant unwanted side effects. Here, our approach targeted PDE–PK complexes as they would occur in signalosomes, thereby offering greater specificity. Our developed fluorescence polarization assay was adapted to identify inhibitors that block cyclic nucleotide pockets in PDE–PK complexes in one mode and disrupt protein-protein interactions between PDEs and PKs in a second mode. We tested this approach with three different systems—cAMP-specific PDE8–PKAR, cGMP-specific PDE5–PKG, and dual-specificity RegA–R_D complexes—and ranked inhibitors according to their inhibition potency. Targeting PDE–PK complexes offers biochemical tools for describing the exquisite specificity of cyclic nucleotide signaling networks in cells.

The Role of PDE8 in T Cell Recruitment and Function in Inflammation

Inhibitors targeting cyclic nucleotide phosphodiesterases (PDEs) expressed in leukocytes have entered clinical practice to treat inflammatory disorders, with three PDE4 inhibitors currently in clinical use as therapeutics for psoriasis, psoriatic arthritis, atopic dermatitis and chronic obstructive pulmonary disease. In contrast, the PDE8 family that is upregulated in pro-inflammatory T cells is a largely unexplored therapeutic target. It was shown that PDE8A plays a major role in controlling T cell and breast cancer cell motility, including adhesion to endothelial cells under physiological shear stress and chemotaxis. This is a unique function of PDE8 not shared by PDE4, another cAMP specific PDE, employed, as noted, as an anti-inflammatory therapeutic. Additionally, a regulatory role was shown for the PDE8A-rapidly accelerated fibrosarcoma (Raf)-1 kinase signaling complex in myelin antigen reactive CD4⁺ effector T cell adhesion and locomotion by a mechanism differing from that of PDE4. The PDE8A-Raf-1 kinase signaling complex affects T cell motility, at least in part, via regulating the LFA-1 integrin mediated adhesion to ICAM-1. The findings that PDE8A and its isoforms are expressed at higher levels in naive and myelin oligodendrocyte glycoprotein (MOG)_35–55 activated effector T (Teff) cells compared to regulatory T (Treg) cells and that PDE8 inhibition specifically affects MOG_35–55 activated Teff cell adhesion, indicates that PDE8A could represent a new beneficial target expressed in pathogenic Teff cells in CNS inflammation. The implications of this work for targeting PDE8 in inflammation will be discussed in this review.

Phosphodiesterase-4 Inhibition in Psoriasis

Psoriasis is a chronic immune-mediated inflammatory disorder. Phosphodiesterase-4 (PDE-4) is an enzyme that mediates inflammatory responses and plays a role in psoriasis pathogenesis. PDE-4 degrades its substrate cyclic adenosine monophosphate (cAMP) to adenosine monophosphate (AMP), which subsequently leads to the production of pro-inflammatory mediators. Inhibitors of PDE-4 work by blocking the degradation of cAMP, which leads to a reduction in inflammation. Apremilast is the only approved oral PDE-4 inhibitor for the treatment of psoriasis. While it is effective for some patients, it may be limited by adverse effects in others. A topical PDE-4 inhibitor, roflumilast, is being investigated in psoriasis and showing promising results. Crisaborole, a topical PDE-4 inhibitor approved for use in atopic dermatitis, has also been investigated in psoriasis. This is an updated comprehensive review to summarize the currently available evidence for the PDE-4 inhibitors apremilast, roflumilast and crisaborole in the treatment of psoriasis, with a focus on data from randomized clinical trials.

Vitiligo: Targeted Therapies Add Color to Disease Pathophysiology

There is excitement in the air for patients with vitiligo. For the first time in decades, we have early case studies showing that targeted therapies can repigment vitiliginous skin, and well-powered clinical trials are underway. However, at the time of this writing, there is no Food and Drug Administration-approved drug for vitiligo. In a randomized clinical trial by Khemis et al. report negative results on a randomized clinical trial testing the combination of apremilast, a phosphodiesterase 4 inhibitor, and narrowband-ultraviolet B versus placebo and narrowband-ultraviolet B in patients with nonsegmental vitiligo. The results of this trial are a reminder that clinical management of vitiligo is challenging at best, even when combining anti-inflammatory and/or immunomodulating agents with repigmenting agents. However, these negative trials are critical in improving our understanding of this complex and disfiguring disease.

A Phase III Randomized Study of Apremilast, an Oral Phosphodiesterase 4 Inhibitor, for Active Ankylosing Spondylitis

OBJECTIVE

To evaluate the efficacy and safety of apremilast, an oral phosphodiesterase 4 inhibitor, in patients with active ankylosing spondylitis (AS).

METHODS

This phase III, multicenter, double-blind, placebo-controlled study (ClinicalTrials.gov: NCT01583374) randomized patients with active AS (1:1:1) to placebo, apremilast 20 mg twice daily, or apremilast 30 mg twice daily for 24 weeks, followed by a long-term extension phase (up to 5 yrs). The primary endpoint was Assessment of the Spondyloarthritis international Society 20 (ASAS20) response at Week 16. The effect of treatment on radiographic outcomes after 104 weeks was assessed using the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS).

RESULTS

In total, 490 patients with active AS were randomized in the study (placebo: n = 164; apremilast 20 mg twice daily: n = 163; apremilast 30 mg twice daily: n = 163). The primary endpoint of ASAS20 response at Week 16 was not met (placebo: 37%; apremilast 20 mg twice daily: 35%; apremilast 30 mg twice daily: 33%; P = 0.44 vs placebo). At Week 104, mean (SD) changes from baseline in mSASSS were 0.83 (3.6), 0.98 (2.2), and 0.57 (1.9) in patients initially randomized to placebo, apremilast 20 mg twice daily, and apremilast 30 mg twice daily, respectively. The most frequently reported adverse events through Week 104 were diarrhea, nasopharyngitis, upper respiratory infection, and nausea.

CONCLUSION

No clinical benefit was observed with apremilast treatment in patients with active AS. The safety and tolerability of apremilast were consistent with its known profile.

Targeting inflammatory cytokine storm to fight against COVID-19 associated severe complications

Such testing and trying time probably never seen before in the human history. The novel coronavirus disease abbreviated as COVID-19 is the ongoing health crisis which entered into human life in late December 2019. The ease of transmission between humans and the undetectability in early stage makes COVID-19 frightening and unprecedented. The disease is characterised by pneumonia progressing to breathing difficulty, acute respiratory distress syndrome (ARDS) and multi-organ failure. Clinical studies suggest excessive release of inflammatory mediators leads to cytokine storm, a phenomenon which appears to be potentially life-threatening in COVID-19. Across the globe, when the world authorities are grappling to contain the virus, our review provides a glimpse on structure, pathophysiology of the virus and further sheds light on various clinical complications associated with the disease in order to open up/raise new horizons to explore various possible theoretical targets for COVID-19. The review also portrays a question and debates: Can targeting cytokine storm can be a feasible approach to combat COVID-19?

Adenylate control in cAMP signaling: implications for adaptation in signalosomes

In cAMP-Protein Kinase A (PKA) signaling, A-kinase anchoring protein scaffolds assemble PKA in close proximity to phosphodiesterases (PDE), kinase-substrates to form signaling islands or 'signalosomes'. In its basal state, inactive PKA holoenzyme (R2:C2) is activated by binding of cAMP to regulatory (R)-subunits leading to dissociation of active catalytic (C)-subunits. PDEs hydrolyze cAMP-bound to the R-subunits to generate 5'-AMP for termination and resetting the cAMP signaling. Mechanistic basis for cAMP signaling has been derived primarily by focusing on the proteins in isolation. Here, we set out to simulate cAMP signaling activation-termination cycles in a signalosome-like environment with PDEs and PKA subunits in close proximity to each other. Using a combination of fluorescence polarization and amide hydrogen exchange mass spectrometry with regulatory (RIα), C-subunit (Cα) and PDE8 catalytic domain, we have tracked movement of cAMP through activation-termination cycles. cAMP signaling operates as a continuum of four phases: (1) Activation and dissociation of PKA into R- and C-subunits by cAMP and facilitated by substrate (2) PDE recruitment to R-subunits (3) Hydrolysis of cAMP to 5'-AMP (4) Reassociation of C-subunit to 5'-AMP-bound-RIα in the presence of excess ATP to reset cAMP signaling to form the inactive PKA holoenzyme. Our results demonstrate that 5'-AMP is not merely a passive hydrolysis end-product of PDE action. A 'ligand-free' state R subunit does not exist in signalosomes as previously assumed. Instead the R-subunit toggles between cAMP- or 5'-AMP bound forms. This highlights, for the first time, the importance of 5'-AMP in promoting adaptation and uncovers adenylate control in cAMP signaling.

Biologic and advanced immunomodulating therapeutic options for sarcoidosis: a clinical update

Introduction: Sarcoidosis is a multi-organ disease with a wide range of clinical manifestations and outcomes. A quarter of sarcoidosis patients require long-term treatment for chronic disease. In this group, corticosteroids and cytotoxic agents be insufficient to control diseaseAreas covered: Several biologic agents have been studied for treatment of chronic pulmonary and extra-pulmonary disease. A review of the available literature was performed searching PubMed and an expert opinion regarding specific therapy was developed.Expert opinion: These agents have the potential of treating patients who have progressive disease. Many of these agents have different mechanisms of action, response rates, and toxicity profiles.

Carbon dioxide inhibits UVB-induced inflammatory response by activating the proton-sensing receptor, GPR65, in human keratinocytes

Carbon dioxide (CO₂) is the predominant gas molecule emitted during aerobic respiration. Although CO₂ can improve blood circulation in the skin via its vasodilatory effects, its effects on skin inflammation remain unclear. The present study aimed to examine the anti-inflammatory effects of CO₂ in human keratinocytes and skin. Keratinocytes were cultured under 15% CO₂, irradiated with ultraviolet B (UVB), and their inflammatory cytokine production was analyzed. Using multiphoton laser microscopy, the effect of CO₂ on pH was observed by loading a three-dimensional (3D)-cultured epidermis with a high-CO₂ concentration formulation. Finally, the effect of CO₂ on UVB-induced erythema was confirmed. CO₂ suppressed the UVB-induced production of tumor necrosis factor-α (TNFα) and interleukin-6 (IL-6) in keratinocytes and the 3D epidermis. Correcting medium acidification with NaOH inhibited the CO₂-induced suppression of TNFα and IL-6 expression in keratinocytes. Moreover, the knockdown of H⁺-sensing G protein-coupled receptor 65 inhibited the CO₂-induced suppression of inflammatory cytokine expression and NF-κB activation and reduced CO₂-induced cyclic adenosine monophosphate production. Furthermore, the high-CO₂ concentration formulation suppressed UVB-induced erythema in human skin. Hence, CO₂ suppresses skin inflammation and can be employed as a potential therapeutic agent in restoring skin immune homeostasis.

H89 Treatment Reduces Intestinal Inflammation and Candida albicans Overgrowth in Mice

Deregulation of the dynamic crosstalk between the gut microbiota, intestinal epithelial cells, and immune cells is critically involved in the development of inflammatory bowel disease and the overgrowth of opportunistic pathogens, including the human opportunistic fungus Candida albicans. In the present study, we assessed the effect of N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H89), a protein kinase A inhibitor, on the migration of macrophages to C. albicans through dextran sulphate sodium (DSS)-challenged Caco-2 cells. We also investigated the impact of H89 on intestinal inflammation and C. albicans clearance from the gut, and determined the diversity of the gut microbiota in a murine model of DSS-induced colitis. H89 reduced the migration of macrophages to C. albicans through DSS-challenged Caco-2 cells. In addition, H89 decreased C. albicans viability and diminished the expression of pro-inflammatory cytokines and innate immune receptors in macrophages and colonic epithelial Caco-2 cells. In mice with DSS-induced colitis, H89 attenuated the clinical and histological scores of inflammation and promoted the elimination of C. albicans from the gut. H89 administration to mice decreased the overgrowth of Escherichia coli and Enterococcus faecalis populations while Lactobacillus johnsonii populations increased significantly. Overall, H89 reduced intestinal inflammation and promoted the elimination of C. albicans from the gut.

Imperfect storm: is interleukin-33 the Achilles heel of COVID-19?

The unique cytokine signature of COVID-19 might provide clues to disease mechanisms and possible future therapies. Here, we propose a pathogenic model in which the alarmin cytokine, interleukin (IL)-33, is a key player in driving all stages of COVID-19 disease (ie, asymptomatic, mild-moderate, severe-critical, and chronic-fibrotic). In susceptible individuals, IL-33 release by damaged lower respiratory cells might induce dysregulated GATA-binding factor 3-expressing regulatory T cells, thereby breaking immune tolerance and eliciting severe acute respiratory syndrome coronavirus 2-induced autoinflammatory lung disease. Such disease might be initially sustained by IL-33-differentiated type-2 innate lymphoid cells and locally expanded γδ T cells. In severe COVID-19 cases, the IL-33-ST2 axis might act to expand the number of pathogenic granulocyte-macrophage colony-stimulating factor-expressing T cells, dampen antiviral interferon responses, elicit hyperinflammation, and favour thromboses. In patients who survive severe COVID-19, IL-33 might drive pulmonary fibrosis by inducing myofibroblasts and epithelial-mesenchymal transition. We discuss the therapeutic implications of these hypothetical pathways, including use of therapies that target IL-33 (eg, anti-ST2), T helper 17-like γδ T cells, immune cell homing, and cytokine balance.

Apremilast Regulates the Teff/Treg Balance to Ameliorate Uveitis via PI3K/AKT/FoxO1 Signaling Pathway

Autoimmune uveitis (AU), being one of the sight-threatening ocular inflammatory disorders, has been widely regarded by ophthalmologists and immunologists as a great challenge. Apremilast, a phosphodiesterase-4 inhibitor (PDE4i), which was approved by the U.S. Food and Drug Administration (FDA) for the treatment of active psoriatic arthritis in 2014, has been attracting researchers, who are exploring its efficiency and mechanism on uveitis. In this study, we used an experimental autoimmune uveitis (EAU), a representative model for human AU, to investigate the effect of apremilast on regulating anti-inflammatory mediators. Our study demonstrated that apremilast treatment resulted in a decrease in vascular leakage, macular edema, and inflammatory cell infiltration in the retina, corresponding to decreased clinical and pathological scores. Specifically, apremilast decreased the proportion and population of Th17 cells and increased the proportion and population of T regulatory (Treg) cells. Mechanistically, apremilast may regulate Th17 and Treg cells by inhibiting the phosphorylation of the phosphoinositide 3-kinase (PI3K)/protein kinase B(AKT)/Forkhead box O1 (FoxO1) signaling pathway. These findings suggested that apremilast alleviated EAU by regulating Th17 and Treg through the PI3K/AKT/FoxO1 pathway.

Apremilast in dermatology: A review of literature

Apremilast is an orally administered small molecule that specifically inhibits the phosphodiesterase-4 enzyme and modulates the immune system by increasing the levels of intracellular cyclic adenosine monophosphate (cAMP) and inhibiting IL-2 & 8, interferon-γ and tumor necrosis factor (TNF) production. It is FDA approved for the treatment of psoriasis, psoriatic arthritis, and oral ulcers of Behcet's disease. More recently, apremilast has been used off-label to treat varied dermatological diseases where systemic corticosteroids or immunosuppressive agents were not effective. We review the efficacy and safety of apremilast in the treatment of aphthous stomatitis, Behçet's disease, chronic actinic dermatitis, atopic dermatitis, cutaneous sarcoidosis, hidradenitis suppurativa, lichen planus, and discoid lupus erythematosus in cases where standard treatment has failed.

Successful Treatment of Refractory Palmoplantar Pustular Psoriasis With Apremilast: A Case Series

Introduction: Palmoplantar pustular psoriasis (PPPP) is a debilitating inflammatory skin disorder of the palms and soles that poses a high burden on affected patients. Satisfactory treatment response is rarely achieved using current treatment options, little is known about the potential benefit of the PDE4 inhibitor apremilast in the treatment of refractory PPPP patients. We aimed to evaluate the use of apremilast in PPPP patients. Patients and Methods: Six patients, four with severe physician global assessment (PGA) = 3 on a scale of 0-4 and two with very severe (PGA = 4) treatment-refractory PPPP [mean age (years ± SD): 56.2 ± 15.6], were included in this study. Five patients had concomitant psoriatic arthritis (PsA). Prior to apremilast administration, topical corticosteroids, psoralen-UVA and multiple systemic oral and biologic anti-inflammatory treatments were insufficient to improve their skin condition or had to be discontinued due to adverse events. Apremilast (titrated to a maintenance dose of 30 mg 2x/d) was commenced in all patients with clinical follow-up over 18 months. Results: Within the first 4 weeks of treatment, each patient's symptoms improved as assessed by PGA score. At 3 months, four patients had a mild PGA score and two were cleared from PPPP. After 18 months of follow-up, three patients improved from PGA = 3 to PGA = 1 and one patient from PGA = 4 to PGA = 1. Two patients discontinued treatment, one due to a lack of efficacy against PsA and the other to a desire to have a child. However, both patients recorded improvements before discontinuing treatment. Conclusion: Apremilast may be a promising treatment option for refractory and severely affected PPPP patients. Our observation, however, requires further validation.

Apremilast and its role in psoriatic arthritis

Psoriatic arthritis (PsA) is a seronegative inflammatory arthritis often observed in patients with skin psoriasis. Treatment of PsA, especially peripheral PsA, has typically relied on disease-modifying anti-rheumatic agents (DMARDs); however, these agents have limited efficacy and considerable associated toxicity. More recently, monoclonal antibodies (biologic agents) have revolutionized management of immune-mediated diseases; however, these therapies carry a high cost and require parenteral administration. Apremilast, a novel oral DMARD, was approved by the European Union for psoriatic arthritis in 2015. Apremilast inhibits the function of phosphodiesterase-4, a regulator of cyclic adenosine monophosphate, leading to a broad inhibition of proinflammatory mediators and subsequent reduction in tumour necrosis factor-alpha (TNF-α) response. The PALACE and ACTIVE trials, phase III randomized controlled trials for apremilast, showed that apremilast is effective at improving various clinical and patient-reported outcome measures for psoriatic arthritis in both DMARD-naïve and DMARD-experienced PsA patients. Efficacy was limited in patients with previous biologic DMARD failure and the overall efficacy of apremilast appears to be less than biologics agents, though no head-to-head trials exist comparing apremilast to biologic DMARDs. Apremilast is generally well tolerated, with short-lived gastrointestinal side effects being the most commonly reported adverse events. Guidelines suggest a trial of apremilast in patients who have failed traditional oral DMARDs and for whom, biologics are contraindicated. More studies directly comparing apremilast to conventional DMARDs and biologic DMARDs are needed and will be crucial in informing clinical and economic decisions about apremilast role in management of PsA.

Apremilast ameliorates ox-LDL-induced endothelial dysfunction mediated by KLF6

Apremilast is a phosphodiesterase 4 (PDE4) inhibitor used in the treatment of psoriasis and several other inflammatory diseases. Interest has been expressed in seeking out therapies that address both psoriasis and atherosclerosis. In the present study, we explored the effects of apremilast in human aortic endothelial cells (HAECs) exposed to oxidized low-density lipoprotein (ox-LDL) to simulate the atherosclerotic microenvironment in vitro. Our findings indicate that apremilast may reduce the expression of lectin-like oxidized-low-density-lipoprotein receptor-1 (LOX-1), the main ox-LDL scavenging receptor. Apremilast also inhibited the expression of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and interleukin-8 (IL-8), which are deeply involved in the chronic inflammatory response associated with atherosclerosis. Interestingly, we found that apremilast inhibited the attachment of U937 monocytes to HAECs by reducing the expression of the chemokine monocyte chemotactic protein 1 (MCP-1) and the cellular adhesion molecule vascular cell adhesion molecule-1 (VCAM-1). This effect was found to be mediated through the rescue of Krüppel like factor 6 (KLF6) expression, which was reduced in response to ox-LDL via increased phosphorylation of c-Jun N-terminal kinase (JNK). These findings suggest a potential role for apremilast in the treatment of atherosclerosis.

Response to Inhibition of Receptor-Interacting Protein Kinase 1 (RIPK1) in Active Plaque Psoriasis: A Randomized Placebo-Controlled Study

Receptor-interacting protein kinase 1 (RIPK1), a regulator of inflammation and cell death, is a potential therapeutic target in immune-mediated inflammatory diseases (IMIDs). The objective of this phase IIa multicenter, randomized, double-blind, placebo-controlled study was to evaluate safety, tolerability pharmacokinetics, pharmacodynamics, and preliminary efficacy of GSK2982772, a RIPK1 inhibitor, in plaque-type psoriasis. Psoriasis patients (N = 65) were randomized to 60 mg twice daily (b.i.d.) or three times daily (t.i.d.), or placebo for 84 days. Most adverse events (AEs) were mild with no severe drug-related AEs reported. Plaque Lesion Severity Sum improved with b.i.d. treatment compared with placebo; interpretation of t.i.d. treatment results was complicated by a high placebo response. Reductions in epidermal thickness and infiltration by CD3+ T cells in the epidermis and dermis were observed compared with placebo. Results support the rationale for additional studies on RIPK1 inhibition in IMIDs.

The effect of apremilast therapy on skin cytokine levels in patients with psoriasis

Objective — Assessment of phosphodiesterase-4 inhibitor (apremilast) therapy’s influence on skin cytokine levels in patients with moderate-to-severe and severe psoriasis. Material and Methods — An open, uncontrolled study was conducted. 16 patients with plaque psoriasis (13 men, 3 women; mean ± standard deviation (SD) age 35.1±9.7 years, range 21-60) were enrolled. The mean Psoriasis Area and Severity Index (PASI) was 20.7±8.93 (range 10-47). All patients were prescribed apremilast 30 milligrams (mg) per os (PO) Bis In Die (BID). The efficacy of therapy was evaluated by PASI at 14 and 26 weeks of therapy. Lesional skin samples were collected at baseline and weeks 14 and 26. Levels of interleukin (IL)-1β, IL-4, IL-6, IL-10, IL-17A, IL-17F, IL-21, IL-22, IL-23, IL-25, IL-31, IL -33, interferon (INF)-γ, Soluble CD40-ligand (sCD40L), tumor necrosis factor (TNF)-α were measured by microsphere-based suspension array technology (Luminex® xMAP™ system). Results — Levels of cytokines (except IL-4 and IL-33) in lesional skin samples were found to have decreased at week 14 compared with those at baseline. Similar decreases were seen for IL-23, IL-25, IL-31, sCD40L at week 26. In contrast, the levels of other cytokines increased again at week 26, in comparison with baseline. Levels of IL-4 and IL-33 rose throughout the follow-up period. Cytokine levels in lesional skin samples were compared with those of healthy controls both at baseline and during therapy. Conclusion — The results of our study show that administering apremilast therapy to patients with psoriasis can bring the levels of cytokines involved in the IL-23/IL-17 axis in the lesional skin to the level of cytokine in non-lesional skin and to the levels in the skin of healthy individuals.

Multidisciplinary Management of the Adverse Effects of Apremilast

We present a series of general and specific recommendations based on pathophysiologic considerations for managing the most common adverse effects of apremilast that lead to treatment discontinuation: diarrhea, nausea, and headache. The recommendations are based on a review of the literature and the experience of a multidisciplinary team of 14 experts including dermatologists, rheumatologists, neurologists, gastroenterologists, pharmacists, and nurses. We propose a series of simple algorithms that include clinical actions and suggestions for pharmacologic treatment. The adverse effects of apremilast can be managed from a multidisciplinary approach. The purpose of optimizing management is to bring clinical benefits to patients.

Switch Rates and Total Cost of Care Associated with Apremilast and Biologic Therapies in Biologic-Naive Patients with Plaque Psoriasis

Purpose

Compare treatment switching rates and costs among biologic-naive psoriasis patients initiating apremilast or biologics.

Methods

This retrospective claims analysis used IBM MarketScan Commercial and Medicare Supplemental databases to identify patients who initiated apremilast or a biologic (ie, tumor necrosis factor [TNF] or interleukin [IL] inhibitor) for psoriasis treatment between January 1, 2015, and December 31, 2016. A 1:1 propensity score matching was used to adjust for possible selection bias and maximize the number of patients available for analysis. Treatment switching, days to switch, and healthcare costs were assessed at 12 months. T-test and chi-square test were used to evaluate differences between cohorts for continuous and categorical variables as appropriate; Wilcoxon rank-sum tests were used to assess cost differences.

Results

In total, 88,025 patients newly initiated apremilast, a TNF inhibitor, or an IL inhibitor. After inclusion/exclusion criteria were applied and patients were propensity score matched, 1645 (apremilast), 1207 (TNF inhibitor), and 438 (IL inhibitor) patients were included in this analysis. Twelve-month switch rates were significantly lower for apremilast initiators compared with TNF inhibitor initiators (14% vs 25%; p<0.01) and comparable to IL inhibitors (14% vs 11%; p>0.05). No statistical difference was observed in days to switch at 12 months for any treatment group. Total healthcare costs were lower for apremilast initiators compared with TNF and IL inhibitor initiators ($34,028 vs $55,973 and $64,430; p<0.0001). Per-patient per-month (PPPM) costs were significantly lower for apremilast initiators compared with TNF inhibitor and IL inhibitor initiators ($2834 vs $4662 and $5366; p<0.0001).

Conclusion

Over a 12-month follow-up, biologic-naive psoriasis patients initiating apremilast had significantly lower switching rates compared with patients on TNF inhibitors and similar rates as patients on IL inhibitors. PPPM and total healthcare costs were significantly lower for patients initiating apremilast vs TNF or IL inhibitors, primarily due to lower pharmacy costs.