Phase 2, randomized, double-blind, placebo-controlled, 4-week study to evaluate the safety and efficacy of OPA- 15406 (difamilast), a new topical selective phosphodiesterase type-4 inhibitor, in Japanese pediatric patients aged 2-14 years with atopic dermatitis

An Interim Report of a Phase 3, Long-Term, Open-Label Study to Evaluate Efficacy and Safety of Difamilast Ointment in Japanese Infants with Atopic Dermatitis

INTRODUCTION

Difamilast is the first selective phosphodiesterase 4 inhibitor approved for atopic dermatitis (AD) in Japan. A phase 3, 52-week, open-label study is ongoing to establish efficacy and safety of difamilast ointments in infants with AD aged 3 to < 24 months because a clinical study has not been conducted in this population.

METHODS

This study consisted of a 4-week primary evaluation period in which difamilast 0.3% ointment was applied twice daily to Japanese infants aged 3 to < 24 months (n = 41) and an ongoing 48-week long-term extension period in which difamilast 0.3% or 1% ointment was applied based on existing symptoms. The data on efficacy and safety of difamilast were obtained as of an interim report in the study period.

RESULTS

The response rate in Investigator's Global Assessment score was 45.0% at week 1, which was maintained at 56.1% at week 4 and 63.4% at the interim report. Infants achieved the response rate in Eczema Area and Severity Index 75 (improvement of ≥ 75%) of 47.5% at week 1, which further improved to 82.9% at week 4 and 78.1% at the interim report. Adverse events (AEs) were reported in 22 (53.7%) infants in the primary evaluation period: of those the most frequent AE was nasopharyngitis (19.5%) followed by dermatitis contact (7.3%). As of the interim report, 36 (87.8%) infants experienced AEs: of those, nasopharyngitis (70.7%) and gastroenteritis (22.0%) were most frequently observed. The total AEs were mostly mild or moderate in severity. No investigational medicinal product-related AEs and no AEs leading to discontinuation were reported.

CONCLUSION

Difamilast ointments applied twice daily to Japanese infants with AD aged 3 to < 24 months is effective and well tolerated as of the interim report in the study period. The final results will be reported in the near future.

CLINICAL TRIAL REGISTRATION

Clinical Trials. gov identifier: NCT05372653.

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.

Discovery of Oxidized p-Terphenyls as Phosphodiesterase 4 Inhibitors from Marine-Derived Fungi

Four new p-terphenyl derivatives, talaroterphenyls A-D (1-4), together with three biosynthetically related known ones (5-7), were obtained from the mangrove sediment-derived Talaromyces sp. SCSIO 41412. Compounds 1-3 are rare p-terphenyls, which are completely substituted on the central benzene ring by oxygen atoms; this is the first report of their isolation from natural sources. Their structures were elucidated through NMR spectroscopy, HRESIMS, and X-ray diffraction. Genome sequence analysis revealed that 1-7 were biosynthesized from tyrosine and phenylalanine, involving four key biosynthetic genes (ttpB-ttpE). These p-terphenyls (1-7) and 36 marine-derived terphenyl analogues (8-43) were screened for phosphodiesterase 4 (PDE4) inhibitory activities, and 1-5, 14, 17, 23, and 26 showed notable activities with IC50 values of 0.40-16 μM. The binding pattern of p-terphenyl inhibitors 1-3 with PDE4 were explored by molecular docking analysis. Talaroterphenyl A (1), with a low cytotoxicity, showed obvious anti-inflammatory activity in LPS-stimulated RAW264.7 cells. Furthermore, in the TGF-β1-induced medical research council cell strain-5 (MRC-5) pulmonary fibrosis model, 1 could down-regulate the expression levels of FN1, COL1, and α-SMA significantly at concentrations of 5-20 μM. This study suggests that the oxidized p-terphenyl 1, as a marine-derived PDE4 inhibitor, could be used as a promising antifibrotic agent.

Topical Treatments in Atopic Dermatitis: An Expansive Review

Atopic dermatitis (AD) is a common inflammatory skin condition found worldwide. It impacts patient quality of life (QoL) and is thought to arise as an inflammatory response to epidermal barrier dysfunction and hypersensitivity. AD can lead to large out-of-pocket costs and increased healthcare expenses over a lifetime. An analysis of all randomized control trials conducted since 1990 on topical therapies for AD were reviewed, including 207 trials in the final analysis. It was found that an average of 226 patients were enrolled over 2.43 arms. Common topical treatments included corticosteroids, calcineurin inhibitors, JAK inhibitors, and phosphodiesterase inhibitors. The most utilized tools to identify treatment efficacy were the EASI, IGA, SCORAD, and PGA. There was a paucity of data on trials that evaluated efficacy, QoL, and cost of treatment simultaneously. This review highlights the need for comprehensive trials that evaluate multiple aspects of treatment, including financial cost and QoL impact, to ensure each patient has the best treatment modality for the management of their AD.

Novel Topical Treatments for Itch

The experience of itch often poses a burden on patient quality of life and has the capacity to inflict significant suffering. Topical therapies are a mainstay of treatment for many cutaneous and systemic diseases and afford patients the opportunity to manage their conditions without many of the systemic side effects of non-topical therapies. We review a multitude of new topical medications targeting the skin, immune system, and neural receptors. The list includes Janus kinase inhibitors, tyrosine kinase inhibitors, phosphodiesterase inhibitors, transient receptor vanilloid inhibitors, topical cannabinoids, and topical acetaminophen. Many of the topical therapies reviewed show promising data in phase 2-3 clinical trials, but further research is needed to compare therapies head-to-head and test their efficacy on a broader range of conditions.

Preclinical pharmacokinetic investigation of the bioavailability and skin distribution of HY-072808 ointment, a novel drug candidate for the treatment of atopic dermatitis, in minipigs by a newly LC-MS/MS method

HY-072808 is a novel phosphodiesterase 4 inhibitor clinically used for topical atopic dermatitis treatment. Cytochrome P450 enzymes are involved in transforming it into major metabolite ZZ-24. An efficient UPLC-MS/MS method was established to detect HY-072808 and ZZ-24 in plasma and skin tissues of minipigs.One-step protein precipitation was performed with acetonitrile. Subsequently, elution was served with a methanol and water gradient containing 0.1% formic acid for 3.5 min. The plasma and skin tissue concentrations of HY-072808 and ZZ-24 showed good linearity from 0.200 to 200 ng/mL.The experimental minipigs exhibited low systemic exposure and bioavailability of 3.1-7.6% after transdermal application of 1-4% HY-072808 ointment. Multiple topical administrations over seven consecutive days showed a minor accumulation in systemic exposure, with accumulation factors of 2.3 and 4.0 for HY-072808 and ZZ-24, respectively.The distribution of HY-072808 ointment among different cortical layers in minipigs was studied for the first time. Following transdermal application of 2% HY-072808 ointment, the concentration in plasma and skin tissues in the order of epidermis > dermis > subcutaneous tissue ≈ subcutaneous muscle ≈ plasma; at 48 h after the administration, the epidermis and dermis still had a high concentration of the drug.

Topical treatments for atopic dermatitis (eczema): Systematic review and network meta-analysis of randomized trials

BACKGROUND

Atopic dermatitis (AD) is a common skin condition with multiple topical treatment options, but uncertain comparative effects.

OBJECTIVE

We sought to systematically synthesize the benefits and harms of AD prescription topical treatments.

METHODS

For the 2023 American Academy of Allergy, Asthma & Immunology and American College of Allergy, Asthma, and Immunology Joint Task Force on Practice Parameters AD guidelines, we searched MEDLINE, EMBASE, CENTRAL, CINAHL, LILACS, ICTRP, and GREAT databases to September 5, 2022, for randomized trials addressing AD topical treatments. Paired reviewers independently screened records, extracted data, and assessed risk of bias. Random-effects network meta-analyses addressed AD severity, itch, sleep, AD-related quality of life, flares, and harms. The Grading of Recommendations Assessment, Development and Evaluation approach informed certainty of evidence ratings. We classified topical corticosteroids (TCS) using 7 groups-group 1 being most potent. This review is registered in the Open Science Framework (https://osf.io/q5m6s).

RESULTS

The 219 included trials (43,123 patients) evaluated 68 interventions. With high-certainty evidence, pimecrolimus improved 6 of 7 outcomes-among the best for 2; high-dose tacrolimus (0.1%) improved 5-among the best for 2; low-dose tacrolimus (0.03%) improved 5-among the best for 1. With moderate- to high-certainty evidence, group 5 TCS improved 6-among the best for 3; group 4 TCS and delgocitinib improved 4-among the best for 2; ruxolitinib improved 4-among the best for 1; group 1 TCS improved 3-among the best for 2. These interventions did not increase harm. Crisaborole and difamilast were intermediately effective, but with uncertain harm. Topical antibiotics alone or in combination may be among the least effective. To maintain AD control, group 5 TCS were among the most effective, followed by tacrolimus and pimecrolimus.

CONCLUSIONS

For individuals with AD, pimecrolimus, tacrolimus, and moderate-potency TCS are among the most effective in improving and maintaining multiple AD outcomes. Topical antibiotics may be among the least effective.

How to get rid of itching

Itch is an unpleasant sensation arising from a variety of dermatologic, neuropathic, systemic, and psychogenic etiologies. Various itch pathways are implicated according to the underlying etiology. A variety of pruritogens, or itch mediators, as well as receptors have been identified and provide potential therapeutic targets. Recent research has primarily focused on targeting inflammatory cytokines and Janus kinase signaling, protease-activated receptors, substance P and neurokinin, transient receptor potential-vanilloid ion channels, Mas-related G-protein-coupled receptors (MRGPRX2 and MRGPRX4), the endogenous opioid and cannabinoid balance, and phosphodiesterase 4. Periostin, a newly identified pruritogen, should be further explored with clinical trials. Drugs targeting neural sensitization including the gabergic system and P2X3 are other potential drugs for chronic itch. There is a need for more targeted therapies to improve clinical outcomes and reduce side effects.

Clinical efficacy and safety of topical difamilast in the treatment of patients with atopic dermatitis: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To investigate the clinical efficacy and safety of topical difamilast in mild-to-moderate atopic dermatitis (AD).

METHODS

Only randomized controlled trials (RCTs) that compared topical difamilast with vehicle treatment for patients with AD were included. PubMed, Web of Science, Ovid Medline, Cochrane Library, ClinicalTrials.gov and JapicCTI were searched to 10 April 2022.

RESULTS

Five studies enrolling a total of 1009 patients with mild-to-moderate AD were identified. Compared with the topical vehicle, topical difamilast was associated with a significantly higher success rate according to the Investigator's Global Assessment score at week 4 (relative risk, 2.82; 95% confidence interval [CI]: 2.11-3.77). Compared with the vehicle, difamilast was associated with a significant decrease in day 28 eczema area and severity index scores (mean difference [MD], -4.10; 95% CI: -5.32 to -2.87), verbal rating scale scores (MD, -0.51; 95% CI: -0.71 to -0.32), visual analog scale scores (MD, -12.15; 95% CI: -19.70 to -4.61), patient-oriented eczema measure values (MD, -3.99; 95% CI: -4.91 to -3.07), and total affected body surface area (MD, -6.48; 95% CI: -8.09 to -4.87). No difference in treatment-related adverse events was identified.

CONCLUSIONS

This meta-analysis suggests that topical difamilast is an effective and safe treatment for mild-to-moderate AD.

Treatment Options for Troublesome Itch

Itch (or pruritus) is an unpleasant sensation, inducing the desire to scratch. It is also a major and distressing symptom of many skin and systemic diseases. The involvement of histamine, which is a major itch mediator, has been extensively examined. Recent studies suggest that histamine-independent pathways may play roles in chronic itch. Therefore, antihistamines are not always effective in the treatment of patients with chronic itch. The development of biologics and κ-opioid receptor (KOR) agonists has contributed to advances in the treatment of itch; however, since biologics are expensive for patients to purchase, some patients may limit or discontinue their use of these agents. Furthermore, KOR agonists need to be prescribed with caution due to risks of side effects in the central nervous system. Janus kinase (JAK) inhibitors are sometimes associated with side effects, such as infection. In this review, we summarize antidepressants, antineuralgics, cyclosporine A, antibiotics, crotamiton, phosphodiesterase 4 inhibitor, botulinum toxin type A, herbal medicines, phototherapy, and acupuncture therapy as itch treatment options other than antihistamines, biologics, opioids, and JAK inhibitors; we also explain their underlying mechanisms of action.

Difamilast Ointment in Japanese Adult and Pediatric Patients with Atopic Dermatitis: A Phase III, Long-Term, Open-Label Study

Introduction

Phosphodiesterase 4 (PDE4), which regulates inflammatory cytokine production leading to atopic dermatitis (AD), is selectively inhibited by difamilast. The objective of this phase III, long-term, open-label study was to evaluate the safety and efficacy of topical difamilast in Japanese adult and pediatric patients with AD.

Methods

Adult patients (n = 166) began treatment with difamilast 1% ointment, and pediatric patients began treatment with difamilast 0.3% ointment (n = 144) or difamilast 1% ointment (n = 56). Treatment was continued twice daily for 52 weeks. All patients had an Investigator’s Global Assessment (IGA) score of 2 (mild), 3 (moderate), or 4 (severe/very severe), and an AD-affected body surface area (BSA) of ≥ 5% before treatment, with no restriction on the upper limit for the AD-affected BSA.

Results

During therapy, 120 adult patients (72.3%) and 178 pediatric patients (89.0%) experienced treatment-emergent adverse events (TEAEs), most of which were mild or moderate in severity. Discontinuation due to TEAEs was reported in 13 adult patients (7.8%) and in 7 pediatric patients (3.5%). Treatment-related adverse events were reported in 14 adult patients (8.4%) and 16 pediatric patients (8.0%), most frequently dermatitis atopic (1.8%) and acne (1.2%) in adult patients and dermatitis atopic and pigmentation disorder (each 2.0%) in pediatric patients. The cumulative success rates in Eczema Area and Severity Index (EASI)-75 in adult and pediatric patients were 55.4% and 73.5%, respectively, at week 52, and the cumulative success rates increased from week 4 to week 52. The cumulative success rates in IGA score showed the same trend as those in EASI -75.

Conclusions

This study demonstrates that difamilast ointments are well tolerated and effective in Japanese adult and pediatric patients with AD when applied twice daily for 52 weeks, and are expected to be used for a long-term treatment for AD.

Clinical Trial Registration

Clinical Trials.gov identifier: NCT03961529.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13555-022-00751-9.

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

Sofpironium bromide: an investigational agent for the treatment of axillary hyperhidrosis

INTRODUCTION

In recent years, increased knowledge about pathophysiology of primary hyperhidrosis has led to novel therapeutic advances. Topical and systemic anticholinergic agents have been proven beneficial in reducing sweat production in primary axillary hyperhidrosis (PAH), although their use is limited by the increased likelihood of systemic anticholinergic drug reactions, particularly regarding systemic agents.

AREAS COVERED

This paper provides an overview of pharmaceutical characteristics, efficacy and safety data from phase II and III clinical trials on sofpironium bromide (SB), a topical anticholinergic agent that has been employed for the treatment of PAH and has already received its first approval in Japan for the treatment of PAH in the form of 5% gel formulation.

EXPERT OPINION

The retrometabolic drug design of topical SB presents distinct advantages, by limiting systemic absorption and therefore development of anticholinergic adverse events. This along with the popularity of the non-greasy gel formulation is expected to increase compliance. However, this therapy still offers a temporary control of PAH, compared to sympathectomy or device-based treatments, such as microwave thermolysis. Hence, physicians should balance the effectiveness against adverse events of each therapeutic modality and use a personalized approach based on patient's needs.

Itch: Pathogenesis and treatment

Itch pathogenesis is broadly characterized into histaminergic and nonhistaminergic pathways and transmitted via 2 main receptor families: G protein-coupled receptors and transient receptor potential channels. In the skin, itch is primarily transmitted by unmyelinated type C and thinly myelinated type Aδ nerve fibers. Crosstalk between the immune and neural systems modulates itch transmission at the skin, spinal cord, and brain. Among the many known pruritogens, Th2 cytokines, such as interleukin-4, interleukin-13, interleukin-31, and thymic stromal lymphopoietin, are particularly important mediators that signal through shared Janus kinase pathways, representing novel targets for novel itch therapeutics. Emerging evidence has also revealed that the opioidergic system is a potent modulator of itch transmission, with increased μ-opioid activity and decreased κ-opioid activity contributing to itch pathogenesis. Optimal management of itch requires that treatment approaches be tailored to specific etiologic itch subtypes. When the etiology is unknown and patients are given a diagnosis of chronic pruritus of unknown origin, treatment should be guided by the presence of Th2 polarization, often reflected by increased blood eosinophils. In the second article of this 2-part series, we outline our current understanding of itch pathogenesis and discuss available and emerging treatments for itch.

Anti-inflammatory topical medication - new developments in the treatment of atopic dermatitis

Atopic dermatitis is a chronic inflammatory disease that arises from polygenic disposition, a dysfunction of the physicochemical epithelial barrier, a cutaneous dysbiosis, and a faulty neurosensory activity and shows a highly individual acuity due to epigenetic factors. An essential component of therapeutic management is the application of anti-inflammatory topical medication. Currently, topical glucocorticoids and topical calcineurin inhibitors are routinely used in reactive and proactive therapy. In recent years, the development of molecular medicine has identified several new therapeutic targets that have enabled the development of innovative therapeutic approaches. In addition to phosphodiesterase-4 inhibitors and aryl hydrocarbon receptor modulators, it is mainly Janus kinase inhibitors with different selectivity that are emerging as new effective and safe options for topical therapy. The current data suggests that in the coming months and years representatives of the above-mentioned substance classes will be approved for topical use.

Efficacy and safety of topical Janus kinase and phosphodiesterase inhibitor-4 inhibitors for the treatment of atopic dermatitis: A network meta-analysis

Topical Janus kinase (JAK) and phosphodiesterase-4 (PDE4) inhibitors are novel treatment approaches for atopic dermatitis (AD). This study aimed to compare the efficacy and safety of JAK and PDE4 inhibitors for AD treatment. The databases of PubMed, EMBASE, Web of Science, and Cochrane Library were searched until June 2021 for eligible studies of AD patients treated with topical JAK and PDE4 inhibitors. Baseline and follow-up data were extracted. Efficacy of JAK inhibitors was evaluated using Investigator's Global Assessment (IGA) achieving "clear" or "almost clear", with 2 points or more improvement from baseline at the end of treatment, referred to as "IGA response"). A Bayesian multiple treatment network meta-analysis with fixed effects was performed. Odds ratio (OR) with 95% credibility interval (CrI) were used for comparing the efficacy of JAK and PDE4 inhibitors with placebo for AD. A total of 10 randomized controlled trials of topical JAK and PDE4 inhibitors with 4689 patients were included for analysis. A total of three topical JAK inhibitors and two topical PDE4 inhibitors were included. Compared with placebo, all JAK and PDE4 inhibitors had higher IGA response at 4 weeks of treatment. Notably, with similar safety profile, tofacitinib 2% b.i.d., ruxolitinib 1.5% b.i.d., and delgocitinib 3% b.i.d. showed favorable IGA response compared with topical tacrolimus and corticosteroids. Ranking analysis suggested that among all included JAK and PDE4 inhibitors, tofacitinib 2% b.i.d. had the highest probability of achieving IGA response (SUCRA = 0.880). Besides, JAK and PDE4 inhibitors showed non-inferior safety profile with placebo. This study confirmed that topical JAK and PDE4 inhibitors had promising treatment efficacy and safety for AD patients. Tofacitinib 2% b.i.d., ruxolitinib 1.5% b.i.d. and delgocitinib 3% b.i.d. showed superior efficacy over other JAK and PDE4 inhibitors.

Atopic dermatitis: an expanding therapeutic pipeline for a complex disease

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a complex pathophysiology that underlies a wide spectrum of clinical phenotypes. AD remains challenging to treat owing to the limited response to available therapies. However, recent advances in understanding of disease mechanisms have led to the discovery of novel potential therapeutic targets and drug candidates. In addition to regulatory approval for the IL-4Ra inhibitor dupilumab, the anti-IL-13 inhibitor tralokinumab and the JAK1/2 inhibitor baricitinib in Europe, there are now more than 70 new compounds in development. This Review assesses the various strategies and novel agents currently being investigated for AD and highlights the potential for a precision medicine approach to enable prevention and more effective long-term control of this complex disease.

Recent advances in understanding of the complex phenotype and mechanisms underlying atopic dermatitis (AD) have revealed multiple new potential targets for pharmacological intervention. Here, Bieber reviews therapeutic strategies and assesses the expanding pipeline for the therapy of AD, highlighting the potential for a precision medicine approach to the management of this complex disorder.

Difamilast ointment, a selective phosphodiesterase 4 inhibitor, in paediatric patients with atopic dermatitis: A phase 3 randomised double-blind, vehicle-controlled trial

Background

In atopic dermatitis (AD), phosphodiesterase 4 (PDE4) inhibition reduces proinflammatory mediators and cytokines. Difamilast is a new selective PDE4 inhibitor.

Objectives

To demonstrate the superiority of topical difamilast to vehicle in Japanese paediatric patients with AD.

Methods

This was a phase III randomized, double‐blind, vehicle‐controlled trial. Patients aged 2–14 years with an Investigator Global Assessment (IGA) score of 2 or 3 received difamilast 0·3% (n = 83), difamilast 1% (n = 85) or vehicle (n = 83) ointment twice daily for 4 weeks.

Results

The primary endpoint was the percentage of patients with an IGA score of 0 or 1 with improvement by at least two grades at week 4. The success rates in IGA score at week 4 were 44·6%, 47·1% and 18·1% in the difamilast 0·3%, difamilast 1% and vehicle groups, respectively. Both difamilast groups demonstrated significantly higher success rates in IGA score compared with vehicle at week 4 [difamilast 0·3% (P < 0·001); difamilast 1% (P < 0·001)]. Regarding secondary endpoints, improvements in Eczema Area and Severity Index (EASI; improvement of ≥ 50%, ≥ 75% and ≥ 90% in overall score) at week 4 were significantly higher in patients in the difamilast 0·3% and 1% groups than those in the vehicle group. EASI score in the difamilast 0·3% and 1% groups was significantly reduced compared with that of patients in the vehicle group at week 1. The significant difference between both the difamilast groups and the vehicle groups was maintained from week 1 through to week 4. Most treatment‐emergent adverse events were mild or moderate, and no serious events or deaths were reported.

Conclusions

Difamilast 0·3% and 1% ointments are superior to vehicle and well tolerated in Japanese paediatric patients with AD.

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.

A phase 3, multicenter, randomized, double-blind, vehicle-controlled, parallel-group study of 5% sofpironium bromide (BBI-4000) gel in Japanese patients with primary axillary hyperhidrosis

A phase 3 study was conducted to verify the efficacy and safety of 5% sofpironium bromide (BBI‐4000) gel (hereinafter referred to as sofpironium) administrated for 6 weeks in Japanese patients with primary axillary hyperhidrosis. The primary efficacy end‐point was the proportion of patients who satisfied both criteria of a Hyperhidrosis Disease Severity Score (HDSS) of 1 or 2 at the end of 6‐week treatment and a 50% or more reduction in total gravimetric weight of sweat at the end of treatment relative to baseline. A total of 281 patients were randomized to receive 5% sofpironium (141 patients) or vehicle (140 patients), and all patients were included in the full analysis set (FAS). In the FAS, 70.1% of patients were female, and the median age was 35.0 years. The proportion of patients who achieved the primary efficacy end‐point was 53.9% in the sofpironium group and 36.4% in the vehicle group, with a statistically significant difference of 17.5% (95% confidence interval, 6.02–28.93) between these two groups (P = 0.003). The incidence of adverse events was 44.0% in the sofpironium group and 30.7% in the vehicle group, and the incidence of adverse drug reactions was 16.3% in the sofpironium group and 5.0% in the vehicle group. Reported adverse events were generally mild or moderate in severity. In the sofpironium group, common events (incidence, ≥5%) were nasopharyngitis (14.2%) and dermatitis/erythema at the application site (8.5%/5.7%), with no serious adverse events reported. This study demonstrated the efficacy and safety of 5% sofpironium.

Treatments for Childhood Atopic Dermatitis: an Update on Emerging Therapies

Atopic dermatitis (AD) is generally considered a T helper type 2-dominated disease. Pediatric AD is usually less severe than adult AD, but it may present as moderate to severe lesions that are inadequately managed by current modalities including emollients/moisturizers, topical corticosteroids (TCSs), topical calcineurin inhibitors (TCIs), and even systemic immunosuppressants (such as cyclosporine, azathioprine, methotrexate, and mycophenolate mofetil). In addition, systemic immunosuppressants are often not recommended for childhood AD by the current guidelines due to their toxicities. Therefore, there is still an unmet need for a safe and effective long-term therapy for pediatric AD patients whose disease is inadequately controlled or who are intolerant to current treatments. The emerging therapeutics for AD focuses on intervening in the inflammatory pathway by targeting specific cytokines/chemokines or their receptors. Monoclonal antibodies against immunoglobulin E (IgE), interleukin (IL)-4 receptor subunit α, IL-5, IL-13, IL-31 receptor subunit α, IL-33, and thymic stromal lymphopoietin (TSLP) have been evaluated clinically for AD. Encouraging results have been reported for many of the biologics, of which the most exciting is dupilumab. Other emerging systemic therapies include small molecules such as baricitinib, abrocitinib, upadacitinib, and tradipitant. Several novel topical agents are under clinical investigation for the treatment of AD, including topical phosphodiesterase 4 (PDE4) inhibitors, Janus kinase (JAK) inhibitors, aryl hydrocarbon receptor (AhR) modulating agents, and transient receptor potential vanilloid subfamily member 1 (TRPV1) antagonists. Accompanied by thorough characterization of different phenotype and endotype subsets, the application of precision medicine could provide new prospects for the optimal treatment of AD.