Safety, tolerability and pharmacokinetics of a novel phosphodiesterase inhibitor, E6005 ointment, in healthy volunteers and in patients with atopic dermatitis

Topical anti-inflammatory treatments for eczema: network meta-analysis

BACKGROUND

Eczema (atopic dermatitis) is the most burdensome skin condition worldwide and cannot currently be prevented or cured. Topical anti-inflammatory treatments are used to control eczema symptoms, but there is uncertainty about the relative effectiveness and safety of different topical anti-inflammatory treatments.

OBJECTIVES

To compare and rank the efficacy and safety of topical anti-inflammatory treatments for people with eczema using a network meta-analysis.

SEARCH METHODS

We searched the Cochrane Skin Specialised Register, CENTRAL, MEDLINE, Embase and trial registries on 29 June 2023, and checked the reference lists of included studies.

SELECTION CRITERIA

We included within-participant or between-participant randomised controlled trials (RCTs) in people of any age with eczema of any severity, but excluded trials in clinically infected eczema, seborrhoeic eczema, contact eczema, or hand eczema. We included topical anti-inflammatory treatments used for at least one week, compared with another anti-inflammatory treatment, no treatment, or vehicle/placebo. Vehicle is a 'carrier system' for an active pharmaceutical substance, which may also be used on its own as an emollient for dry skin. We excluded trials of topical antibiotics used alone, complementary therapies, emollients used alone, phototherapy, wet wraps, and systemic treatments.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Primary outcomes were patient-reported eczema symptoms, clinician-reported eczema signs and investigator global assessment. Secondary outcomes were health-related quality of life, long-term control of eczema, withdrawal from treatment/study, and local adverse effects (application-site reactions, pigmentation changes and skin thinning/atrophy were identified as important concerns through patient and public involvement). We used CINeMA to quantify our confidence in the evidence for each outcome.

MAIN RESULTS

We included 291 studies involving 45,846 participants with the full spectrum of eczema severity, mainly conducted in high-income countries in secondary care settings. Most studies included adults, with only 31 studies limited to children aged < 12 years. Studies usually included male and female participants, multiple ethnic groups but predominantly white populations. Most studies were industry-funded (68%) or did not report their funding sources/details. Treatment duration and trial participation were a median of 21 and 28 days (ranging from 7 days to 5 years), respectively. Interventions used were topical corticosteroids (TCS) (172), topical calcineurin inhibitors (TCI) (134), phosphodiesterase-4 (PDE-4) inhibitors (55), janus kinase (JAK) inhibitors (30), aryl hydrocarbon receptor activators (10), or other topical agents (21). Comparators included vehicle (170) or other anti-inflammatory treatments. The risk of bias was high in 242 of the 272 (89.0%) trials contributing to data analyses, most commonly due to concerns about selective reporting. Network meta-analysis (NMA) was only possible for short-term outcomes. Patient-reported symptoms NMA of 40 trials (6482 participants) reporting patient-reported symptoms as a binary outcome ranked tacrolimus 0.1% (OR 6.27, 95% CI 1.19 to 32.98), potent TCS (OR 5.99, 95% CI 2.83 to 12.69), and ruxolitinib 1.5% (OR 5.64, 95% CI 1.26 to 25.25) as the most effective, all with low confidence. Mild TCS, roflumilast 0.15%, and crisaborole 2% were the least effective. Class-level sensitivity analysis found potent/very potent TCS had similar effectiveness to potent TCI and was more effective than mild TCI and PDE-4 inhibitors. NMA of 29 trials (3839 participants) reporting patient-reported symptoms as a continuous outcome ranked very potent TCS (SMD -1.99, 95% CI -3.25 to -0.73; low confidence) and tacrolimus 0.03% (SMD -1.57, 95% CI -2.42 to -0.72; moderate confidence) the highest. Direct information for tacrolimus 0.03% was based on one trial of 60 participants at high risk of bias. Roflumilast 0.15%, delgocitinib 0.25% or 0.5%, and tapinarof 1% were the least effective. Class-level sensitivity analysis found potent/very potent TCS had similar effectiveness to potent TCI and JAK inhibitors and mild/moderate TCS was less effective than mild TCI. A further 50 trials (9636 participants) reported patient-reported symptoms as a continuous outcome but could not be included in NMA. Clinician-reported signs NMA of 32 trials (4121 participants) reported clinician signs as a binary outcome and ranked potent TCS (OR 8.15, 95% CI 4.99, 13.57), tacrolimus 0.1% (OR 8.06, 95% CI 3.30, 19.67), ruxolitinib 1.5% (OR 7.72, 95% CI 4.92, 12.10), and delgocitinib 0.5% (OR 7.61, 95% CI 3.72, 15.58) as most effective, all with moderate confidence. Mild TCS, roflumilast 0.15%, crisaborole 2%, and tapinarof 1% were the least effective. Class-level sensitivity analysis found potent/very potent TCS more effective than potent TCI, mild TCI, JAK inhibitors, PDE-4 inhibitors; and mild TCS and PDE-4 inhibitors had similar effectiveness. NMA of 49 trials (5261 participants) reported clinician signs as a continuous outcome and ranked tacrolimus 0.03% (SMD -2.69, 95% CI -3.36, -2.02) and very potent TCS (SMD -1.87, 95% CI -2.69, -1.05) as most effective, both with moderate confidence; roflumilast 0.15%, difamilast 0.3% and tapinarof 1% were ranked as least effective. Direct information for tacrolimus 0.03% was based on one trial in 60 participants with a high risk of bias. For some sensitivity analyses, potent TCS, tacrolimus 0.1%, ruxolitinib 1.5%, delgocitinib 0.5% and delgocitinib 0.25% became some of the most effective treatments. Class-level analysis found potent/very potent TCS had similar effectiveness to potent TCI and JAK inhibitors, and moderate/mild TCS was more effective than mild TCI. A further 100 trials (22,814 participants) reported clinician signs as a continuous outcome but could not be included in NMA. Investigator Global Assessment NMA of 140 trials (23,383 participants) reported IGA as a binary outcome and ranked ruxolitinib 1.5% (OR 9.34, 95% CI 4.8, 18.18), delgocitinib 0.5% (OR 10.08, 95% CI 2.65, 38.37), delgocitinib 0.25% (OR 6.87, 95% CI 1.79, 26.33), very potent TCS (OR 8.34, 95% CI 4.73, 14.67), potent TCS (OR 5.00, 95% CI 3.80, 6.58), and tacrolimus 0.1% (OR 5.06, 95% CI 3.59, 7.13) as most effective, all with moderate confidence. Mild TCS, crisaborole 2%, pimecrolimus 1%, roflumilast 0.15%, difamilast 0.3% and 1%, and tacrolimus 0.03% were the least effective. In a sensitivity analysis of low risk of bias information (12 trials, 1639 participants), potent TCS, delgocitinib 0.5% and delgocitinib 0.25% were most effective, and pimecrolimus 1%, roflumilast 0.15%, difamilast 1% and difamilast 0.3% least effective. Class-level sensitivity analysis found potent/very potent TCS had similar effectiveness to potent TCI and JAK inhibitors and were more effective than PDE-4 inhibitors; mild/moderate TCS were less effective than potent TCI and had similar effectiveness to mild TCI. Longer-term outcomes over 6 to 12 months showed a possible increase in effectiveness for pimecrolimus 1% versus vehicle (4 trials, 2218 participants) in a pairwise meta-analysis, and greater treatment success with mild/moderate TCS than pimecrolimus 1% (based on 1 trial of 2045 participants). Local adverse effects NMA of 83 trials (18,992 participants, 2424 events) reporting application-site reactions ranked tacrolimus 0.1% (OR 2.2, 95% CI 1.53, 3.17; moderate confidence), crisaborole 2% (OR 2.12, 95% CI 1.18, 3.81; high confidence), tacrolimus 0.03% (OR 1.51, 95%CI 1.10, 2.09; low confidence), and pimecrolimus 1% (OR 1.44, 95% CI 1.01, 2.04; low confidence) as most likely to cause site reactions. Very potent, potent, moderate, and mild TCS were least likely to cause site reactions. NMA of eight trials (1786 participants, 3 events) reporting pigmentation changes found no evidence for increased pigmentation changes with TCS and crisaborole 2%, with low confidence for mild, moderate or potent TCS and moderate confidence for crisaborole 2%. NMA of 25 trials (3691 participants, 36 events) reporting skin thinning found no evidence for increased skin thinning with short-term (median 3 weeks, range 1-16 weeks) use of mild TCS (OR 0.72, 95% CI 0.12, 4.31), moderate TCS (OR 0.91, 95% CI 0.16, 5.33), potent TCS (OR 0.96, 95% CI 0.21, 4.43) or very potent TCS (OR 0.88, 95% CI 0.31, 2.49), all with low confidence. Longer-term outcomes over 6 to 60 months showed increased skin thinning with mild to potent TCS versus TCI (3 trials, 4069 participants, 6 events with TCS).

AUTHORS' CONCLUSIONS

Potent TCS, JAK inhibitors and tacrolimus 0.1% were consistently ranked as amongst the most effective topical anti-inflammatory treatments for eczema and PDE-4 inhibitors as amongst the least effective. Mild TCS and tapinarof 1% were ranked amongst the least effective treatments in three of five efficacy networks. TCI and crisaborole 2% were ranked most likely to cause local application-site reactions and TCS least likely. We found no evidence for increased skin thinning with short-term TCS but an increase with longer-term TCS.

New and Upcoming Topical Treatments for Atopic Dermatitis: A Review of the Literature

Atopic dermatitis (AD) is a chronic inflammatory dermatosis with periods of exacerbation and remissions. AD is characterized by intense, persistent pruritus and heterogeneity in clinical symptomatology and severity. Therapeutic goals include the amelioration of cutaneous eruptions, diminishing relapses and eventually the disease burden. To date, topical corticosteroids (TCS) and calcineurin inhibitors (TCI) have yet been deemed the mainstay of topical treatments in AD management. Nevertheless, despite their indisputable efficiency, TCS and TCI are not indicated for continuous long-term use given their safety profile. While research in AD has concentrated predominantly on systemic therapies, more than 30 novel topical compounds are under development. The existing data appear encouraging, with some regimens that are already FDA-approved (ruxolitinib was the most recent in September 2021) and several pharmaceutical pipeline products for mild-to-moderate AD that are in an advanced stage of development, such as tapinarof, difamilast and roflumilast. Larger, long-term studies are still required to evaluate the efficacy and safety of these novel compounds in the long run and weigh their advantages over present treatments. In this review, we aim to provide an overview of the latest knowledge about AD topical treatments, echoing upcoming research trends.

Safety profile and tolerability of topical phosphodiesterase 4 inhibitors for the treatment of atopic dermatitis: A systematic review and meta-analysis

Objective

Methods

Results

Conclusions

Phosphodiesterase‑4 inhibitors: a review of current developments (2013-2021)

INTRODUCTION

Cyclic nucleotide phosphodiesterase 4 (PDE4) is responsible for the hydrolysis of cAMP, which has become an attractive therapeutic target for lung, skin, and severe neurological diseases. Here, we review the current status of development of PDE4 inhibitors since 2013 and discuss the applicability of novel medicinal-chemistry strategies for identifying more efficient and safer inhibitors.

AREAS COVERED

This review summarizes the clinical development of PDE4 inhibitors from 2013 to 2021, focused on their pharmacophores, the strategies to reduce the side effects of PDE4 inhibitors and the development of subfamily selective PDE4 inhibitors.

EXPERT OPINION

To date, great efforts have been made in the development of PDE4 inhibitors, and researchers have established a comprehensive preclinical database and collected some promising data from clinical trials. Although four small-molecule PDE4 inhibitors have been approved by FDA for the treatment of human diseases up to now, further development of other reported PDE4 inhibitors with strong potency has been hampered due to the occurrence of severe side effects. There are currently three main strategies for overcoming the dose limitation and systemic side effects, which provide new opportunities for the clinical development of new PDE4 inhibitors.

New and Emerging Therapies for Pediatric Atopic Dermatitis

Atopic dermatitis (AD) is a chronic, inflammatory skin disease characterized by pruritus, inflammatory erythematous skin lesions, and skin-barrier defect. Current mainstay treatments of emollients, steroids, calcineurin inhibitors, and immunosuppressants have limited efficacy and potentially serious side effects. Recent advances and understanding of the pathogenesis of AD have resulted in new therapies that target specific pathways with increased efficacy and the potential for less systemic side effects. New FDA-approved therapies for AD are crisaborole and dupilumab. The JAK-STAT inhibitors (baricitinib, upadacitinib, PF-04965842, ASN002, tofacitinib, ruxolitinib, and delgocitinib) have the most promising results of the emerging therapies. Other drugs with potential include the aryl hydrocarbon receptor modulating agent tapinarof, the IL-4/IL-13 antagonists lebrikizumab and tralokinumab, and the IL-31Rα antagonist nemolizumab. In this review, new and emerging AD therapies will be discussed along with their mechanisms of action and their potential based on clinical study data.

Phosphodiesterase-4 Inhibitors for the Treatment of Inflammatory Diseases

Phosphodiesterase-4 (PDE4), mainly present in immune cells, epithelial cells, and brain cells, manifests as an intracellular non-receptor enzyme that modulates inflammation and epithelial integrity. Inhibition of PDE4 is predicted to have diverse effects via the elevation of the level of cyclic adenosine monophosphate (cAMP) and the subsequent regulation of a wide array of genes and proteins. It has been identified that PDE4 is a promising therapeutic target for the treatment of diverse pulmonary, dermatological, and severe neurological diseases. Over the past decades, numerous PDE4 inhibitors have been designed and synthesized, among which roflumilast, apremilast, and crisaborole were approved for the treatment of inflammatory airway diseases, psoriatic arthritis, and atopic dermatitis, respectively. It is regrettable that the dramatic efficacies of a drug are often accompanied by adverse effects, such as nausea, emesis, and gastrointestinal reactions. However, substantial advances have been made to mitigate the adverse effects and obtain better benefit-to-risk ratio. This review highlights the dialectical role of PDE4 in drug discovery and the disquisitive details of certain PDE4 inhibitors to provide an overview of the topics that still need to be addressed in the future.

Adult atopic dermatitis: new and emerging therapies

INTRODUCTION

Adult atopic dermatitis (AD) is very difficult to manage. Indeed, AD in adults is frequently refractory to topical treatment, especially with regards to the persistent form. Therefore, long-term treatment with oral immunosuppressive therapy is often required to control the burden of the disease, prevent flare-ups and achieve better patient quality of life outcomes. Areas covered: In the last decade the better understanding of AD pathogenesis has been used to improve treatment strategies with many emerging therapeutics options. Epidermal barrier impairment often plays the initial role in the initiation of the disease. Moreover, T helper 2 cytokines interleukin (IL)-4 and IL-13 and their downstream effects are prominent in AD, with pleiotropic effects on the innate and adaptive immune system. Targeting these cells, their products or receptors appears to be a reasonable therapeutic strategy. Expert commentary: In the next years, many therapeutic options for adult AD will be available. Clinical trials showed that JAK inhibitors, PDE-4 inhibitors and monoclonal antibodies against some IL (IL-4, IL 13, IL-17, IL-22, IL-31) seem to be the most promising drugs, but dermatologists will have to evaluate their effectiveness and safety in clinical practice.

Topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor, for the treatment of atopic dermatitis

INTRODUCTION

Local adverse effects of steroid use and the burning sensation of calcineurin inhibitors impair patients' adherence to treatment and decrease the treatment response in atopic dermatitis (AD). Steroid phobia appears to be a psychological problem in patients with AD. Topical non-steroidal remedies are in demand. Areas covered: This manuscript reviews the current literature on preclinical and clinical studies regarding topical E6005/RVT-501, a novel phosphodiesterase 4 inhibitor. We also discuss the mechanistic background of E6005/RVT-501 in the treatment of AD. Expert opinion: Topical E6005/RVT-501 improves skin eruption and pruritus of pediatric and adult AD patients without any serious side effects. It is useful for mild to moderate lesions of AD in pediatric and adult patients. Topical E6005/RVT-501 is non-steroidal agent but its potency is equal to that of mild rank topical steroid, therefore, it may fit the demand of patients with steroid phobia. Its steroid-sparing effects may also be investigated in future clinical trials and may minimize the dose and frequency of topical steroids.

Immunologic Targets in Atopic Dermatitis and Emerging Therapies: An Update

Atopic dermatitis is one of the most common chronic inflammatory skin diseases. It usually begins in childhood, has a considerable impact on patients' quality of life, and incurs substantial healthcare costs. The standard-of-care treatments for patients with moderate to severe disease are very limited and have variable and typically insufficient efficacy and many side effects, some of which are quite serious. However, over the last decade, considerable advances in our understanding of the pathogenesis of atopic dermatitis have paved the way for a number of new treatments. Most notable are the drugs that target the Th2-polarized immune system, which is thought to play a key role in many of the signs and symptoms characteristic of this disease. In this article, we briefly review the pathophysiology of atopic dermatitis, while noting that each patient's disease phenotype is likely due to a unique interplay of several disease-specific dysregulated pathways. Lastly, we cover emerging therapies for atopic dermatitis, focusing on those that target specific components of the immune system, which are altered in atopic dermatitis. The hope is that these new biologics or small-molecule antagonists, which have high specificity for their target molecules, will decrease the undesirable side effects caused by off-target effects commonly observed with current immunosuppressive agents that are characterized by broad biological actions.

The IL-17-Th1/Th17 pathway: an attractive target for lung cancer therapy?

INTRODUCTION

There is strong pharmaceutical development of agents targeting the IL-17-TH17 pathway for the treatment of psoriasis (Ps) and psoriatic arthritis (PsA). Lung cancer accounts for 28% of all cancer-related deaths worldwide, and roughly 80% of patients with newly-diagnosed non-small cell lung cancer (NSCLC) present with metastatic disease, with a poor prognosis of around 12 months. Therefore, there is a high unmet medical need for the development of new and potent systemic treatments in this deadly disease. The emergence of immunotherapies such as anti-PD-1 or anti-PDL1 as candidate therapies in non-small cell lung cancer (NSCLC) indicates that targeting critical immuno-modulatory cytokines including those within the IL-17-Th1/Th17 axis may have proven benefit in the treatment of lung cancer. Areas covered: In this review we describe the current evidence for aberrant IL-17-Th1/Th17 settings in cancer, particularly with regard to targeting this axis in NSCLC. We further discuss the current agents under pharmaceutical development which could potentially target this axis, and discuss the current limitations and areas of concern regarding the use of these in lung cancer. Expert opinion: Current evidence suggests that moving forward agents targeting the IL-17-Th1/Th17 pathway may have novel new oncoimmunology indications in the treatment paradigm for NSCLC.