Treatment of Skin Inflammation with Benzoxaborole Phosphodiesterase Inhibitors: Selectivity, Cellular Activity, and Effect on Cytokines Associated with Skin Inflammation and Skin Architecture Changes

Phosphodiesterase-4 Inhibitors Increase Pigment Cell Proliferation and Melanization in Cultured Melanocytes and within a 3-Dimensional Skin Equivalent Model

Vitiligo is a common chronic autoimmune disease characterized by white macules and patches of the skin, having a negative impact on patients' life and without any definitive cure at present. Identification of new compounds to reverse depigmentation is therefore a pressing need for this disease. The pharmacologic compounds phosphodiesterase-4 inhibitors (PDE4is) are small molecules with immunomodulatory properties used for treatment of inflammatory dermatoses. PDE4is have shown repigmentation effects in patients with vitiligo, in some case reports. We characterized the proliferative and melanogenic potential of 2 known PDE4is-crisaborole and roflumilast-and of a more recently designed compound, PF-07038124. We used 2 in vitro model systems-the primary human melanocyte culture and a 3-dimensional cocultured skin model (MelanoDerm)-with an exploratory testing platform composed of complementary assays (spectrophotometry, melanin and proliferation assays, immunostaining, Fontana-Masson staining, RT-qPCR, western blot, and whole-transcriptome RNA sequencing). We identified that treatment with PDE4is was associated with increased melanocyte proliferation and melanization in both in vitro models and with increase in the melanogenic genes and proteins expression in cultured melanocytes. These effects were found to be enhanced by addition of α-melanocyte-stimulating hormone. Our findings support the further evaluation of PDE4is with or without α-melanocyte-stimulating hormone agonists in vitiligo trials.

Role of PDE4 Family in Cardiomyocyte Physiology and Heart Failure

Phosphodiesterase 4 (PDE4) is a key regulator of cyclic adenosine monophosphate (cAMP) signalling in cardiomyocytes, controlling contractility, calcium handling, and hypertrophic responses. PDE4 provides spatial and temporal precision to cAMP signalling, particularly under β-adrenergic stimulation, through its compartmentalised activity in subcellular nanodomains, including the sarcoplasmic reticulum, plasma membrane and nuclear envelope. This review highlights the cardiac PDE4 isoforms PDE4A, PDE4B and PDE4D, focusing on their distinct localisation and contributions to cardiac physiology and pathophysiology, particularly in heart failure and arrhythmias. Although PDE4 plays a smaller role in overall cAMP hydrolysis in human hearts than in rodents, its compartmentalised function remains critical. Recent therapeutic advances have shifted from pan-PDE4 inhibitors to isoform-specific approaches to enhance efficacy while minimising systemic toxicity. We discuss the potential of selective PDE4 modulators, gene therapies and combination strategies in restoring cAMP compartmentation and preventing maladaptive cardiac remodelling. By integrating rodent and human studies, this review underscores the translational challenges and therapeutic opportunities surrounding PDE4, positioning it as both a key regulator of cardiac signalling and a promising target for heart failure therapies.

Efficacy and Safety of Once-Daily Roflumilast Cream 0.05% in Pediatric Patients Aged 2-5 Years With Mild-to-Moderate Atopic Dermatitis (INTEGUMENT-PED): A Phase 3 Randomized Controlled Trial

BACKGROUND/OBJECTIVES

Efficacy and safety of roflumilast cream 0.15% were demonstrated in patients aged ≥ 6 years with atopic dermatitis (AD) in two Phase 3 trials. This Phase 3 parallel-group, double-blind trial (INTEGUMENT-PED; NCT04845620) compared the efficacy and safety of roflumilast cream 0.05% and a vehicle in patients aged 2-5 years with AD.

METHODS

Patients aged 2-5 years with mild-to-moderate AD were treated with once-daily roflumilast cream 0.05% or vehicle for 4 weeks. The primary efficacy endpoint was Validated Investigator Global Assessment for AD (vIGA-AD) Success (0 [Clear] or 1 [Almost Clear] plus ≥ 2-grade improvement from baseline) at Week 4. Other endpoints included ≥ 75% improvement in Eczema Area and Severity Index (EASI-75) and Worst Itch-Numeric Rating Score (WI-NRS) Success (≥ 4-point improvement in patients with baseline ≥ 4). Safety and tolerability were also assessed.

RESULTS

Among 437 and 215 patients treated with roflumilast and vehicle, respectively, significantly greater proportions of the roflumilast group achieved Week-4 vIGA-AD Success (25.4% vs. 10.7%; p < 0.0001), EASI-75 (39.4% vs. 20.6%; p < 0.0001), and WI-NRS Success (35.3% vs. 18.0%; nominal p = 0.0002). Improvement in pruritus was observed within 24 h after the first application (nominal p = 0.0014). Treatment-emergent adverse event (TEAE) rates were low in both groups, and 98.9% were mild or moderate. At all timepoints, stinging/burning that caused definite discomfort was reported by ≤ 0.7% of caregivers of patients in the roflumilast group.

CONCLUSIONS

In this Phase 3 trial, once-daily roflumilast cream 0.05% improved AD signs/symptoms in patients aged 2-5 years, with early pruritus improvement, low AE rates, and local tolerability comparable with vehicle.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT04845620.

Tape-strip profiling identifies unique immune and lipid dysregulation in patients with seborrheic dermatitis

BACKGROUND

Seborrheic dermatitis (SD) is a common, chronic inflammatory skin disease with limited understanding of its pathophysiology. Molecular profiling has been limited by invasiveness of sampling methods.

OBJECTIVE

To analyze the molecular skin profile of adult patients with SD using tape strips.

METHODS

Tape-strips obtained from facial lesions of 26 adult SD patients and 18 demographically matched healthy controls were evaluated with RNA sequencing.

RESULTS

SD molecular skin fingerprint was characterized by strong and significant upregulation of interleukin (IL)23/T-helper (Th)17 and Th22 (i.e. IL23A, IL22, PI3, LL37, S100A8, S100A12), some Th1 skewing (OASL, STAT1, CXCL9), and limited Th2 modulation. A parallel downregulation of barrier markers (CLDN1/8, FA2H, ELOVL3) was also observed.

LIMITATIONS

Limited representation of mild and severe SD patients.

CONCLUSION

These data deepen our understanding of SD suggesting that it has robust Th17/Th22, some Th1 skewing, and minimal Th2 activation, and associated skin barrier alterations. This provides rationale for novel immunomodulatory treatment approaches for SD patients targeting IL23/Th17 and/or Th22 pathways.

Cyclic nucleotide phosphodiesterases as drug targets

Cyclic nucleotides are synthesized by adenylyl and/or guanylyl cyclase, and downstream of this synthesis, the cyclic nucleotide phosphodiesterase families (PDEs) specifically hydrolyze cyclic nucleotides. PDEs control cyclic adenosine-3',5'monophosphate (cAMP) and cyclic guanosine-3',5'-monophosphate (cGMP) intracellular levels by mediating their quick return to the basal steady state levels. This often takes place in subcellular nanodomains. Thus, PDEs govern short-term protein phosphorylation, long-term protein expression, and even epigenetic mechanisms by modulating cyclic nucleotide levels. Consequently, their involvement in both health and disease is extensively investigated. PDE inhibition has emerged as a promising clinical intervention method, with ongoing developments aiming to enhance its efficacy and applicability. In this comprehensive review, we extensively look into the intricate landscape of PDEs biochemistry, exploring their diverse roles in various tissues. Furthermore, we outline the underlying mechanisms of PDEs in different pathophysiological conditions. Additionally, we review the application of PDE inhibition in related diseases, shedding light on current advancements and future prospects for clinical intervention. SIGNIFICANCE STATEMENT: Regulating PDEs is a critical checkpoint for numerous (patho)physiological conditions. However, despite the development of several PDE inhibitors aimed at controlling overactivated PDEs, their applicability in clinical settings poses challenges. In this context, our focus is on pharmacodynamics and the structure activity of PDEs, aiming to illustrate how selectivity and efficacy can be optimized. Additionally, this review points to current preclinical and clinical evidence that depicts various optimization efforts and indications.

Exploring the Therapeutic Landscape: A Narrative Review on Topical and Oral Phosphodiesterase-4 Inhibitors in Dermatology

Phosphodiesterase-4 (PDE4) is involved in the synthesis of inflammatory cytokines that mediate several chronic inflammatory disorders, including psoriasis and atopic dermatitis. In recent years, the therapeutic armamentarium in dermatology has expanded with the introduction of PDE4 inhibitors, both in oral and topical formulations. PDE4 inhibitors have gained increasing interest due to their remarkable safety record and ease of prescription, as evidenced by the recent influx of literature detailing its off-label uses. Apremilast was the first PDE4 inhibitor approved by the US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for psoriasis, psoriatic arthritis, and oral ulcers of Behcet's disease. Off-label use has been reported in diverse dermatological conditions, including aphthous stomatitis, chronic actinic dermatitis, atopic dermatitis, cutaneous sarcoidosis, hidradenitis suppurativa, lichen planus, and discoid lupus erythematosus. Roflumilast is a PDE4 inhibitor that was approved by the FDA and the EMA as an oral treatment of chronic obstructive pulmonary disease. Since patent expiration, several generic formulations of oral roflumilast have become available, and various studies have documented its off-label use in psoriasis and other dermatological conditions such as hidradenitis suppurativa, recurrent oral aphthosis, nummular eczema, lichen planus, and Behçet's disease. Topical roflumilast has received FDA approval for treatment of plaque psoriasis and seborrheic dermatitis. The favorable safety profile encourages its long-term use as an alternative to corticosteroids, addressing the chronic nature of many dermatological conditions. New oral PDE4 inhibitors are being developed, such as orismilast (LEO-32731), mufemilast (Hemay005), difamilast (OPA-15406) or lotamilast (E6005/RVT-501), among others. This narrative review provides a comprehensive synthesis of the pharmacology, clinical efficacy, safety profile, and practical considerations regarding the oral and topical use of PDE4 inhibitors in dermatology.

Long-Term Safety and Efficacy with Roflumilast Cream 0.15% in Patients Aged ≥6 Years with Atopic Dermatitis: A Phase 3 Open-Label Extension Trial

Background: Safety and efficacy of roflumilast cream 0.15% for atopic dermatitis (AD) were demonstrated in two 4-week phase 3 trials. Objective: Evaluate long-term safety, tolerability, and efficacy of roflumilast cream 0.15% in AD. Methods: In this open-label extension (OLE) trial (INTEGUMENT-OLE; NCT04804605), patients aged ≥6 years who completed one of the 4-week phase 3 trials applied roflumilast for up to 52 weeks. After 4 weeks of once-daily application, patients who achieved Validated Investigator Global Assessment for AD (vIGA-AD) of clear (0) switched to twice-weekly (BIW) application to normal-appearing flare-prone areas (proactive treatment). Results: Among 657 patients treated, 36.7% reported adverse events, including 4.7% that were treatment related. Application site pain and stinging/burning that caused definite discomfort at any visit were reported for 0.5% and 0.4%-2.1% of patients, respectively. Patients who achieved vIGA-AD 0 and switched to proactive BIW application maintained vIGA-AD 0/1 (almost clear) for a median of 281 days (Kaplan-Meier estimate). Conclusion: Roflumilast cream 0.15% was well tolerated for up to 56 weeks. BIW application to normal-appearing flare-prone sites maintained improvement in AD signs and symptoms, showing that proactive treatment represents an alternative to the current standard practice of reactive treatment.

Phosphodiesterases: Evolving Concepts and Implications for Human Therapeutics

Phosphodiesterases (PDEs) are a superfamily of enzymes that hydrolyze cyclic nucleotides. While the 11 PDE subfamilies share common features, key differences confer signaling specificity. The differences include substrate selectivity, enzymatic activity regulation, tissue expression, and subcellular localization. Selective inhibitors of each subfamily have elucidated the protean role of PDEs in normal cell function. PDEs are also linked to diseases, some of which affect the immune, cardiac, and vascular systems. Selective PDE inhibitors are clinically used to treat these specific disorders. Ongoing preclinical studies and clinical trials are likely to lead to the approval of additional PDE-targeting drugs for therapy in human disease. In this review, we discuss the structure and function of PDEs and examine current and evolving therapeutic uses of PDE inhibitors, highlighting their mechanisms and innovative applications that could further leverage this crucial family of enzymes in clinical settings.

Topical Application of Dipyridamole and Roflumilast Combination Nanoparticles Loaded Nanoemulgel for the Treatment of Psoriasis in Rats

Background

Phosphodiesterase-4 is an enzyme that regulates immune responses and contributes to the development of psoriasis. Dipyridamole and roflumilast function as phosphodiesterase-4 inhibitors, reducing pro-inflammatory cytokine expression. The aim was to evaluate the anti-psoriatic effect of the topical administration of dipyridamole and roflumilast nanoemulgel combination on imiquimod-induced psoriasiform skin inflammation in rats.

Methods

Dipyridamole and roflumilast were formulated into nanoemulgel to enhance skin penetration and retention. The production of nanoemulgels involves a two-part process. A nanoemulsion is created (the aqueous phase titration method was employed to create nanoemulsions‎), which is then incorporated into the gelling agent during the second phase. The new formula was then tested in rats. The rats were divided into seven groups; all animals were treated for 16 days. Induction was achieved by 120 mg of 5% imiquimod cream, which was applied daily for 8 days. After induction, groups received one of the following: 0.05% clobetasol ointment, 1% dipyridamole nanoemulgel (D-NEG), 0.3% roflumilast nanoemulgel (R-NEG), 1% dipyridamole and 0.3% roflumilast gel combination (DR-gel), and 1% dipyridamole and 0.3% roflumilast nanoemulgel combination (DR-NEG). At the end of the experiment, all animals were euthanized, and their blood and skin tissue samples were obtained. Inflammatory markers, immunohistochemistry, and histopathology were measured.

Results

The DR-NEG group showed significantly lower levels of IL17, IL23, and TNF-α, while TGF-β showed higher levels than the clobetasol group. The expression of CK16 was significantly lower compared to the clobetasol group. DR-NEG showed a significantly lower PASI and Baker score than the clobetasol group.

Conclusion

The new DR-NEG's topical combination administration showed better anti-inflammatory, tissue healing, and anti-psoriatic activity than each drug alone or topical clobetasol administration; this could be attributed to the possible synergic effects of both drugs and the enhanced skin penetration offered by the nanoemulgel formulation.

Roflumilast Cream, 0.15%, for Atopic Dermatitis in Adults and Children: INTEGUMENT-1 and INTEGUMENT-2 Randomized Clinical Trials

Importance

Safe, effective, and well-tolerated topical treatment options available for long-term use in patients with atopic dermatitis (AD) are limited and associated with low adherence rates.

Objective

To evaluate efficacy and safety of once-daily roflumilast cream, 0.15%, vs vehicle cream in patients with AD.

Design, Setting, and Participants

Two phase 3, randomized, double-blind, vehicle-controlled trials (Interventional Trial Evaluating Roflumilast Cream for the Treatment of Atopic Dermatitis 1 and 2 [INTEGUMENT-1 and INTEGUMENT-2]), included patients from sites in the US, Canada, and Poland. Participants were 6 years or older with mild to moderate AD based on Validated Global Assessment for Atopic Dermatitis (assessed on a 5-point scale ranging from 0 [clear] to 4 [severe]).

Intervention

Patients were randomized 2:1 to receive roflumilast cream, 0.15%, or vehicle cream once daily for 4 weeks.

Main Outcomes and Measures

The primary efficacy end point was Validated Investigator Global Assessment for Atopic Dermatitis success at week 4, defined as a score of 0 or 1 plus at least a 2-grade improvement from baseline. Secondary end points included Eczema Area and Severity Index and Worst Itch Numeric Rating Scale. Safety and local tolerability were also evaluated.

Results

Among 1337 patients (654 patients in INTEGUMENT-1 and 683 patients in INTEGUMENT-2), the mean (SD) age was 27.7 (19.2) years, and 761 participants (56.9%) were female. The mean body surface area involved was 13.6% (SD = 11.6%; range, 3.0% to 88.0%). Significantly more patients treated with roflumilast than vehicle achieved the primary end point (INTEGUMENT-1: 32.0% vs 15.2%, respectively; P < .001; INTEGUMENT-2: 28.9% vs 12.0%, respectively; P < .001). At week 4, statistically significant differences favoring roflumilast also occurred for the achievement of at least 75% reduction in the Eczema Area and Severity Index (INTEGUMENT-1: 43.2% vs 22.0%, respectively; P < .001; INTEGUMENT-2: 42.0% vs 19.7%, respectively; P < .001). Roflumilast was well tolerated with low rates of treatment-emergent adverse events. At each time point, investigators noted no signs of irritation at the application site in 885 patients who were treated with roflumilast (≥95%), and 885 patients who were treated with roflumilast (90%) reported no or mild sensation at the application site.

Conclusions and Relevance

In 2 phase 3 trials enrolling adults and children, once-daily roflumilast cream, 0.15%, improved AD relative to vehicle cream, based on multiple efficacy end points, with favorable safety and tolerability.

Trial Registration

ClinicalTrials.gov Identifiers: NCT04773587, NCT04773600.

Addressing Unmet Needs in Atopic Dermatitis: Evaluating Disease-Modifying Capabilities of Current and Emerging Therapies

Atopic dermatitis (AD) is a highly burdensome inflammatory skin condition affecting nearly one-quarter of the pediatric population and often continuing into adulthood. Despite recent advancements in systemic therapies providing temporary symptom relief over the past decade, AD frequently remains difficult to control, necessitating increased dosages or alternative treatments due to recurrent disease. This review synthesizes current literature to identify unmet needs of treating AD beyond medication-related limitations and evaluates existing therapies for their efficacy in modifying underlying disease mechanisms. Key findings include variability in AD pathophysiology and phenotypes across different age groups and ethnicities, indicating a need for research into endotype-specific treatments. The literature also comprises evidence suggesting that select current drugs, such as targeted biologics and Janus Kinase (JAK) inhibitors, may offer long-term disease-modifying benefits. Future management strategies should explore novel approaches, including manipulation of the microbiome, immune response, and neural function, as these may lead to additional improvements in AD treatment and long-term symptom relief.

[Phosphodiesterase 4 inhibitors in dermatology : Role in the treatment of skin diseases]

BACKGROUND

Chronic inflammatory skin diseases are of great social and medical importance and require effective drug therapy. Phosphodiesterase 4 (PDE4) inhibitors represent a possible therapeutic option by regulating inflammatory processes. PDEs cause the release of proinflammatory cytokines by interfering with signaling pathways. The PDE4 inhibitors apremilast (treatment of psoriasis and Behçet's disease), roflumilast (treatment of chronic obstructive pulmonary disease), and crisaborole (treatment of atopic dermatitis) are currently approved in Europe.

PSORIASIS

Apremilast is used for second-line treatment of plaque psoriasis and psoriatic arthritis and has a favorable side effect profile. Topical PDE4 inhibitors are currently being researched and have not yet been approved by the European Medicines Agency (EMA).

ATOPIC DERMATITIS

The topical PDE4 inhibitor crisaborole was approved by the EMA in 2020 as a topical treatment alternative to glucocorticoids and calcineurin inhibitors. Although the substance has shown good tolerability in studies and also alleviates the accompanying itching, it did not find its way onto the German market. BEHçET'S DISEASE: Apremilast is approved for the treatment of Behçet's disease in adults with refractory, severe oral ulcers.

OUTLOOK

Case studies have also demonstrated the efficacy of systemic PDE4 inhibition in other skin diseases (including blistering autoimmune dermatoses, lichen planus, and acantholytic genodermatoses). The substances are also being researched and used to treat extracutaneous inflammatory diseases.

Crisaborole combined with vitamin D demonstrates superior therapeutic efficacy over either monotherapy in mice with allergic contact dermatitis

This study evaluated the therapeutic efficacy and underlying mechanisms of crisaborole combined with vitamin D in the treatment of allergic contact dermatitis. While crisaborole, a phosphodiesterase 4 inhibitor, and vitamin D analogs are commonly used in the treatment of atopic dermatitis, their combined therapeutic potential in allergic contact dermatitis (ACD) remains unexplored. Given their anti-inflammatory properties, we hypothesized that the combination of crisaborole and vitamin D could offer superior efficacy in mitigating the symptoms and underlying mechanisms of allergic contact dermatitis. In vitro, HaCaT cells stimulated with tumor necrosis factor-α and interferon-γ were treated with a combination of crisaborole and vitamin D, followed by cytokine expression analysis. In vivo, male C57BL/6 mice were divided into five groups and treated accordingly: blank control, dinitrochlorobenzene-induced model, crisaborole alone, vitamin D alone, and a combination of crisaborole and vitamin D. On day 14, dorsal skin and ear thickness were measured, followed by comprehensive pathological evaluations. In vivo and in vitro experiments showed that the expression levels of inflammatory factors were significantly lower in the DNCB + VD + Cri group than in the DNCB group. Histological analyses revealed that, compared with the DNCB group, the combined treatment group significantly reduced epidermal hyperkeratosis, improved epidermal transdermal water loss, decreased dermatitis scores, and diminished mast cell infiltration. Moreover, it lowered the expression levels of IL-6, IL-4, TNF-α, iNOS, IL-17, CC chemokine ligand 2 (CCL2), and CC chemokine receptor 2 (CCR2). CCL2 recognizes CCR2 and stimulates inflammatory cells, enhancing the inflammatory response. Increased CCL2 expression correlates with heightened inflammation and dendritic cell infiltration in ACD, while downregulation of CCL2 attenuates inflammation. Thus, the combined use of crisaborole and vitamin D demonstrates superior therapeutic efficacy over monotherapy in a mouse model of ACD. The combination of vitamin D and crisaborole significantly reduces inflammation and epidermal hyperkeratosis in a mouse model of allergic contact dermatitis, demonstrating superior therapeutic efficacy compared to either treatment alone. This suggests that the combined therapy could be a promising approach for the prevention and treatment of allergic contact dermatitis.

Long-term safety and effectiveness of roflumilast cream 0.3% in adults with chronic plaque psoriasis: A 52-week, phase 2, open-label trial

BACKGROUND

Efficacy and/or safety profiles limit topical psoriasis treatments.

OBJECTIVE

Evaluate long-term effects of once-daily roflumilast cream 0.3% in patients with psoriasis.

METHODS

In this open-label phase 2 trial, adult patients (N = 332) with psoriasis who completed the phase 2b parent trial or were newly enrolled applied roflumilast once-daily for 52 weeks. Safety and effectiveness were assessed.

RESULTS

Overall, 244 patients (73.5%) completed the trial; 13 patients (3.9%) discontinued due to adverse events (AEs) and 3 (0.9%) due to lack of efficacy. Twelve patients (3.6%) reported treatment-related AEs; none were serious. ≥97% of patients had no irritation. No tachyphylaxis was observed with 44.8% of the patients achieving Investigator Global Assessment (IGA) Clear or Almost Clear at Week 52.

LIMITATIONS

Intertriginous-IGA and Psoriasis Area and Severity Index (PASI) were not evaluated in all patients.

CONCLUSIONS

In this long-term trial, once-daily roflumilast cream was well-tolerated and efficacious up to 64 weeks in patients in the earlier trial, suggesting it is suitable for chronic treatment, including the face and intertriginous areas.

The Psoriasis Treatment Pipeline: An Overview and Update

Significant research advances in our understanding of psoriatic disease have led to the development of several highly selective, effective, and safe topical and systemic treatments. These treatments have led to unprecedented levels of disease clearance and control for most patients with psoriasis with cutaneous disease. However, there remains a need for improved treatments for those patients with recalcitrant disease, psoriatic arthritis, or nonplaque disease variants. Recently approved therapies and investigational products in ongoing clinical development programs that target IL-17A/F, IL-23, TYK2, PDE4, AhR or IL-36 cytokine signaling are improving the clinician's ability to care for a broader range of patients affected by psoriasis.

Vitiligo non-responding lesions to narrow band UVB have intriguing cellular and molecular abnormalities that may prevent epidermal repigmentation

We have discovered that human vitiligo patients treated with narrow-band UVB (NBUVB) demonstrated localized resistance to repigmentation in skin sites characterized by distinct cellular and molecular pathways. Using immunostaining studies, discovery-stage RNA-Seq analysis, and confirmatory in situ hybridization, we analyzed paired biopsies collected from vitiligo lesions that did not repigment after 6 months of NBUVB treatment (non-responding) and compared them with repigmented (responding) lesions from the same patient. Non-responding lesions exhibited acanthotic epidermis, had low number of total, proliferative, and differentiated melanocyte (MC) populations, and increased number of senescent keratinocytes (KCs) and of cytotoxic CD8+ T cells as compared with responding lesions. The abnormal response in the non-responding lesions was driven by a dysregulated cAMP pathway and of upstream activator PDE4B, and of WNT/β-catenin repigmentation pathway. Vitiligo-responding lesions expressed high levels of WNT10B ligand, a molecule that may prevent epidermal senescence induced by NBUVB, and that in cultured melanoblasts prevented the pro-melanogenic effect of α-MSH. Understanding the pathways that govern lack of NBUVB-induced vitiligo repigmentation has a great promise in guiding the development of new therapeutic strategies for vitiligo.

Roflumilast foam 0.3% for adolescent and adult patients with seborrheic dermatitis: A randomized, double-blinded, vehicle-controlled, phase 3 trial

BACKGROUND

The topical phosphodiesterase 4 inhibitor roflumilast has been studied in several dermatologic conditions.

OBJECTIVE

Roflumilast foam 0.3% is being investigated as a topical treatment for seborrheic dermatitis (SD).

METHODS

In this phase 3, double-blinded trial, patients with SD were randomly assigned (2:1 ratio) to once-daily roflumilast foam 0.3% or vehicle foam for 8 weeks. The primary efficacy outcome was Investigator Global Assessment (IGA) Success at week 8, defined as IGA of 0 (Clear) or 1 (Almost Clear) plus ≥2-point improvement from baseline. Safety was also assessed.

RESULTS

79.5% of roflumilast-treated and 58.0% of vehicle-treated patients met the primary endpoint (P < .001); statistically significant differences in IGA Success also favored roflumilast at week 2 (roflumilast: 43.0%; vehicle: 25.7%; P < .001) and week 4 (roflumilast: 73.1%; vehicle: 47.1%; P < .001). Roflumilast was well-tolerated with a low rate of treatment-emergent adverse events.

LIMITATIONS

Study limitations include the 8-week treatment period for this chronic condition.

CONCLUSIONS

Once-daily roflumilast foam was superior to vehicle in leading to IGA of Clear or Almost Clear plus ≥2-point improvement from baseline at 8 weeks in patients with SD. Longer trials are needed to determine durability and safety of roflumilast foam in SD.

Topical and Oral Roflumilast in Dermatology: A Narrative Review

Oral roflumilast is a phosphodiesterase-4 inhibitor approved for the prevention of exacerbations of chronic obstructive pulmonary disease and chronic bronchitis. In dermatology, topical roflumilast is authorized by the US Food and Drug Administration for the treatment of plaque psoriasis and mild to moderate seborrheic dermatitis. Several studies have described the off-label use of roflumilast in dermatology, including a randomized controlled trial showing its usefulness in the treatment of psoriasis; case reports and small series have also reported successful outcomes in hidradenitis suppurativa, recurrent oral aphthosis, nummular eczema, lichen planus, and Behçet disease. Roflumilast has a favorable safety profile, similar to that of apremilast, and it is considerably cheaper than new generation drugs and even some conventional immunosuppressants. We review the pharmacokinetics and pharmacodynamics of topical and oral roflumilast and discuss potential adverse effects and both approved and off-label uses in dermatology. Roflumilast is a promising agent to consider.

[Translated aticle] Topical and Oral Roflumilast in Dermatology: A Narrative Review

Oral roflumilast is a phosphodiesterase-4 inhibitor approved for the prevention of exacerbations of chronic obstructive pulmonary disease and chronic bronchitis. In dermatology, topical roflumilast is authorized by the US Food and Drug Administration for the treatment of plaque psoriasis and mild to moderate seborrheic dermatitis. Several studies have described the off-label use of roflumilast in dermatology, including a randomized controlled trial showing its usefulness in the treatment of psoriasis; case reports and small series have also reported successful outcomes in hidradenitis suppurativa, recurrent oral aphthosis, nummular eczema, lichen planus, and Behçet disease. Roflumilast has a favorable safety profile, similar to that of apremilast, and it is considerably cheaper than new generation drugs and even some conventional immunosuppressants. We review the pharmacokinetics and pharmacodynamics of topical and oral roflumilast and discuss potential adverse effects and both approved and off-label uses in dermatology. Roflumilast is a promising agent to consider.

Topical Management of Pediatric Psoriasis: A Review of New Developments and Existing Therapies

Psoriasis is a chronic immune-mediated disorder that commonly affects adults and children. In recent years, pediatric psoriasis has increased in prevalence and the disease is often associated with various comorbidities and psychological distress. The conventional topical treatments for psoriasis, such as corticosteroids, calcineurin inhibitors, vitamin D analogs, anthralin, and coal tar, are often limited by their side effects, tolerability, and/or efficacy, particularly for use in children and on sensitive and intertriginous areas. Recently, the US Food and Drug Administration approved two new topical non-steroidal agents for treating psoriasis that target different pathogenic pathways than the conventional treatments. Roflumilast is a phosphodiesterase type 4 inhibitor approved for the treatment of plaque psoriasis in patients aged 12 years and older. Tapinarof is a novel aryl hydrocarbon receptor modulator approved for adult psoriasis and currently undergoing studies for pediatric psoriasis. Ongoing efforts are also being made to optimize conventional treatments, for instance, a new foam formulation of halobetasol propionate was recently approved for pediatric psoriasis. Clinical trials of various new drugs targeting one or multiple pathogenic pathways of psoriasis, such as Janus kinase inhibitors, different formulations of phosphodiesterase type 4 inhibitors, and aryl hydrocarbon receptor modulators have also been explored. The recent emergence of novel topical agents provides promising new options for managing pediatric psoriasis with the potential to improve clinical outcomes and quality of life. In this article, we review the mechanism of action, efficacy, and safety profile of novel topical agents and discuss their potential roles in the management of pediatric psoriasis.

Phosphodiesterase-4 Inhibition in the Management of Psoriasis

Psoriasis is a common chronic immune-mediated disease with many comorbidities and impacts on quality of life. Among the treatments for psoriasis, phosphodiesterase-4 (PDE4) inhibitors are emerging with expanding options. PDE4 inhibitors play a pivotal role in the inflammatory cascade by degrading cyclic adenosine monophosphate (cAMP), contributing to pro-inflammatory mediator production. Apremilast, an oral PDE4 inhibitor, is approved for psoriasis. While effective, its adverse effects can limit its utility. Roflumilast, a topical PDE4 inhibitor, was also recently approved for psoriasis and shows promise in clinical trials. Crisaborole, a PDE4 inhibitor approved for atopic dermatitis, has also been studied in psoriasis. This review summarizes evidence from randomized clinical trials regarding the efficacy and safety of PDE4 inhibitors in psoriasis treatment. By highlighting their potential benefits and limitations, this review provides valuable insights for clinicians and researchers aiming to optimize psoriasis management.

Next Generation PDE4 Inhibitors that Selectively Target PDE4B/D Subtypes: A Narrative Review

For decades, topical corticosteroids have been the mainstay of treatment for mild-to-moderate inflammatory skin diseases, even though only short-term use is approved for these agents and systemic inflammation is not addressed. Increased understanding of the immunopathogenesis of these conditions, especially for psoriasis and atopic dermatitis, has facilitated the development of antibody-based drugs that neutralize single key cytokines or their associated receptors, such as interleukin (IL)-17A/F, IL-23, and IL-17RA in psoriasis and IL-13 and IL-4Rα in atopic dermatitis. However, oral therapy is still preferred by many patients owing to the ease of use and needle-free administration. Phosphodiesterase 4 (PDE4) inhibitors have been approved for both oral and topical use for inflammatory skin diseases. In this review, we present a summary of an emerging class of selective PDE4B/D inhibitors under clinical development and compare the differences in selectivity of this new generation of PDE4 inhibitors with the less selective currently approved PDE4 inhibitors.

Elemental exchange: Bioisosteric replacement of phosphorus by boron in drug design

Continuous efforts are being directed toward the employment of boron in drug design due to its advantages and unique characteristics including a plethora of target engagement modes, lower metabolism, and synthetic accessibility, among others. Phosphates are components of multiple drug molecules as well as clinical candidates, since they play a vital role in various biochemical functions, being components of nucleotides, energy currency- ATP as well as several enzyme cofactors. This review discusses the unique chemistry of boron functionalities as phosphate bioisosteres - "the boron-phosphorus elemental exchange strategy" as well as the superiority of boron groups over other commonly employed phosphate bioisosteres. Boron phosphate-mimetics have been utilized for the development of enzyme inhibitors as well as novel borononucleotides. Both the boron functionalities described in this review-boronic acids and benzoxaboroles-contain a boron connected to two oxygens and one carbon atom. The boron atom of these functional groups coordinates with a water molecule in the enzyme site forming a tetrahedral molecule which mimics the phosphate structure. Although boron phosphate-mimetic molecules - FDA-approved Crisaborole and phase II/III clinical candidate Acoziborole are products of the boron-phosphorus bioisosteric elemental exchange strategy, this technique is still in its infancy. The review aims to promote the use of this strategy in future medicinal chemistry projects.

Roflumilast 0.3% Cream: a Phosphodiesterase 4 Inhibitor for the Treatment of Chronic Plaque Psoriasis

BACKGROUND

Plaque psoriasis is a chronic dermatologic autoimmune disease that affects adults and children. Roflumilast 0.3% cream is currently the only topical phosphodiesterase 4 inhibitor indicated for the treatment of plaque psoriasis in patients 12 years or older.

PHARMACODYNAMICS AND PHARMACOKINETICS

Roflumilast inhibits phosphodiesterase 4 inhibitor enzyme leading to the accumulation of cyclic adenosine monophosphate, which suppresses the inflammatory mediators interferon-γ and tumor necrosis factor-α. Roflumilast, applied once daily, reaches steady state by day 15 and has a half life of approximately 4 days in adults. Roflumilast undergoes extensive hepatic metabolism by cytochrome P450 enzymes and conjugation. Roflumilast is 99% bound to plasma proteins.

CLINICAL TRIALS

Roflumilast efficacy and safety were evaluated in the DERMIS-1 and DERMIS-2 clinical trials. These identically designed, double-blind, vehicle-controlled phase 3 trials randomized 881 patients to roflumilast 0.3% cream or vehicle, applied once daily for 8 weeks. In DERMIS-1, the Investigator Global Assessment success rate was 42.4% with roflumilast 0.3% cream compared with 6.1% with the vehicle (32.3%-46.9%; P <0.001). Similarly, in DERMIS-2, the Investigator Global Assessment success rate was 37.5% with roflumilast 0.3% cream compared with 6.9% with the vehicle (20.8%-36.9%; P <0.001). Of 881 participants, 1% discontinued treatment with roflumilast cream due to adverse reactions compared with 1.3% treated with vehicle. Urticaria at the application site (0.3%) was the most common adverse reaction that led to discontinuation of roflumilast.

THERAPEUTIC ADVANCE

To date, topical corticosteroids are the most commonly used agents to treat mild plaque psoriasis. Sensitive areas are often challenging to treat with existing topical therapy, including corticosteroids. Topical roflumilast has shown to be effective in treating sensitive areas, including skin folds, and may be an alternative to systemic therapy for some patients. The Food and Drug Administration approved topical roflumilast for the treatment of plaque psoriasis, including intertriginous areas, for patients 12 years or older.

Crisaborole Inhibits Itch and Pain by Preventing Neutrophil Infiltration in a Mouse Model of Atopic Dermatitis

Crisaborole, a phosphodiesterase 4 (PDE4) inhibitor, has been approved for the treatment of mild to moderate atopic dermatitis. Atopic dermatitis is often associated with increased pain. Using a mouse model, this study investigated whether crisaborole suppresses pain associated with atopic dermatitis and the potential mechanisms underlying it. The mouse model for atopic dermatitis was developed by repeatedly applying MC903. MC903-treated mice had increased spontaneous scratching (itch-related behaviour) and wiping behaviour (pain-related behaviour). Crisaborole was topically applied to the cheek skin of MC903-treated mice, and it reduced both itch- and pain-related behaviours in these mice. Immunofluorescence staining revealed that crisaborole reduced neutrophil infiltration and interaction of neutrophils with sensory neurones. Intradermal injection of S100A8/A9, proinflammatory neutrophil mediator, enhanced not only itch-related behaviours evoked by histamine or chloroquine, but also pain-related behaviours evoked by capsaicin. Calcium imaging of mouse dorsal root ganglion neurones revealed that pretreatment with S100A8/A9 significantly increased calcium responses to histamine and capsaicin, and the proportion of chloroquine-sensitive neurones. These findings suggest that the PDE4 inhibitor reduces itch and pain, in part by inhibiting infiltration of S100A8/A9-containing neutrophils in a mouse model of MC903-induced atopic dermatitis.

Topical roflumilast for the treatment of psoriasis

INTRODUCTION

New non-steroidal topical agents are needed for the treatment of psoriasis. Roflumilast cream 0.3% is a once daily phosphodiesterase-4 inhibitor that was recently approved by the FDA for the treatment of plaque psoriasis in adolescents and adults. It is indicated for use on all body surfaces including intertriginous areas.

AREAS COVERED

In this review, we summarize the current knowledge about roflumilast cream for the treatment of psoriasis, highlighting its efficacy and safety profile from published clinical trials. Roflumilast's mechanism of action and pharmacokinetic profile are also discussed.

EXPERT OPINION

Positive results were reported across trials with 48% of patients treated with roflumilast achieving an Investigator Global Assessment score of clear or almost clear at 8 weeks in phase III studies. Most adverse events were mild or moderate in severity and few application-site reactions were reported among participants. Unique advantages of the cream are its success in treating intertriginous areas and its ability to reduce symptoms of itch, results of which may significantly improve quality of life for patients. In the future, real-world data and active comparator trials with existing non-steroidal agents are needed to better understand roflumilast's place in the current treatment landscape.

Efficacy of Roflumilast Foam, 0.3%, in Patients With Seborrheic Dermatitis: A Double-blind, Vehicle-Controlled Phase 2a Randomized Clinical Trial

Importance

Current topical treatment options for seborrheic dermatitis are limited by efficacy and/or safety.

Objective

To assess safety and efficacy of roflumilast foam, 0.3%, in adult patients with seborrheic dermatitis affecting the scalp, face, and/or trunk.

Design, Setting, and Participants

This multicenter (24 sites in the US and Canada) phase 2a, parallel group, double-blind, vehicle-controlled clinical trial was conducted between November 12, 2019, and August 21, 2020. Participants were adult (aged ≥18 years) patients with a clinical diagnosis of seborrheic dermatitis for a 3-month or longer duration and Investigator Global Assessment (IGA) score of 3 or greater (at least moderate), affecting 20% or less body surface area, including scalp, face, trunk, and/or intertriginous areas. Data analysis was performed from September to October 2020.

Interventions

Once-daily roflumilast foam, 0.3% (n = 154), or vehicle foam (n = 72) for 8 weeks.

Main Outcomes and Measures

The main outcome was IGA success, defined as achievement of IGA score of clear or almost clear plus 2-grade improvement from baseline, at week 8. Secondary outcomes included IGA success at weeks 2 and 4; achievement of erythema score of 0 or 1 plus 2-grade improvement from baseline at weeks 2, 4, and 8; achievement of scaling score of 0 or 1 plus 2-grade improvement from baseline at weeks 2, 4, and 8; change in Worst Itch Numeric Rating Scale (WI-NRS) score from baseline; and WI-NRS success, defined as achievement of 4-point or greater WI-NRS score improvement in patients with baseline WI-NRS score of 4 or greater. Safety and tolerability were also assessed.

Results

A total of 226 patients (mean [SD] age, 44.9 [16.8] years; 116 men, 110 women) were randomized to roflumilast foam (n = 154) or vehicle foam (n = 72). At week 8, 104 (73.8%) roflumilast-treated patients achieved IGA success compared with 27 (40.9%) in the vehicle group (P < .001). Roflumilast-treated patients had statistically significantly higher rates of IGA success vs vehicle at week 2, the first time point assessed. Mean (SD) reductions (improvements) on the WI-NRS at week 8 were 59.3% (52.5%) vs 36.6% (42.2%) in the roflumilast and vehicle groups, respectively (P < .001). Roflumilast was well tolerated, with the rate of adverse events similar to that of the vehicle foam.

Conclusions and Relevance

The results from this phase 2a randomized clinical trial of once-daily roflumilast foam, 0.3%, demonstrated favorable efficacy, safety, and local tolerability in the treatment of erythema, scaling, and itch caused by seborrheic dermatitis, supporting further investigation as a nonsteroidal topical treatment.

Trial Registration

ClinicalTrials.gov Identifier: NCT04091646.

Effect of Roflumilast Cream (ARQ-151) on Itch and Itch-Related Sleep Loss in Adults with Chronic Plaque Psoriasis: Patient-Reported Itch Outcomes of a Phase 2b Trial

BACKGROUND

Itch is the most bothersome symptom reported by patients with psoriasis. Safe and effective treatments for psoriasis that also address itch are needed.

OBJECTIVES

To report effects of roflumilast cream on itch-related outcomes from a Phase 2b trial.

METHODS

Adults with chronic plaque psoriasis were randomized to roflumilast 0.3%, roflumilast 0.15%, or vehicle once-daily for 12 weeks. Psoriasis severity was assessed via the Investigator Global Assessment (IGA; a 5-point scale assessing plaque thickening, scaling, and erythema ranging from 0 [clear] to 4 [severe]) and ≥ 2 on a modified Psoriasis Area and Severity Index (PASI-HD, which combines severity of lesions and area affected, ranging from 0 [no disease] to 72 [maximal disease], with the actual percentage of the anatomical area involved in those patients with < 10% of anatomical area involved [e.g., 0.1 for 1% to 0.9 for 9%]). Itch was evaluated via Worst Itch Numeric Rating Scale (WI-NRS), Psoriasis Symptom Diary (PSD) Items 1 (severity of itch) and 2 (bother of itch), and itch-related sleep loss NRS scores. Post hoc correlation analyses between WI-NRS and PASI, WI-NRS and itch-related sleep loss, and WI-NRS and DLQI were also performed.

RESULTS

Roflumilast-treated patients had significantly greater improvements than vehicle-treated patients in WI-NRS and PSD Items 1 and 2 beginning at Week 2 and in itch-related sleep loss Weeks 6 through 12. Among patients with baseline WI-NRS ≥ 6, significantly more patients achieved ≥ 4-point improvement with roflumilast than with vehicle as early as Week 2. Itch severity had low correlation with PASI while WI-NRS and IGA were not always aligned.

LIMITATIONS

The first assessment was at 2 weeks, limiting the ability to assess early onset of itch response.

CONCLUSION

Roflumilast cream improved itch and itch-related sleep loss associated with chronic plaque psoriasis.

CLINICALTRIALS

GOV IDENTIFIER

NCT03638258.

Pharmacokinetics of Roflumilast Cream in Chronic Plaque Psoriasis: Data from Phase I to Phase III Studies

BACKGROUND

Most patients with chronic plaque psoriasis receive topical treatment; however, available options lack a balance of efficacy with long-term safety and tolerability. Roflumilast cream 0.3% is a highly potent phosphodiesterase 4 (PDE4) inhibitor approved by the US FDA for treatment of psoriasis.

OBJECTIVE

The aim of this study was to define the pharmacokinetic (PK) profile of roflumilast delivered topically from a phase I maximal usage study and data from phase II and phase III studies.

METHODS

PK data for roflumilast and the active metabolite, roflumilast N-oxide, were determined from a phase I PK and safety maximal usage study of roflumilast cream 0.3% applied once daily for 14 days in patients with plaque psoriasis affecting body surface area (BSA) ≥20% (N = 26). Serial plasma samples were obtained on Days 1 and 15 to determine maximum plasma concentration (C_max) and area under the concentration-time curve (AUC). Plasma concentrations were also assessed at Weeks 3, 4, and 5 for terminal half-life (t_½). Concentrations of roflumilast and roflumilast N-oxide in skin were assessed at Day 28 for 14 patients with psoriasis in a phase I/IIa study of once-daily roflumilast cream 0.5% and 0.15% for 28 days. Systemic exposure (C_trough and AUC) of roflumilast and roflumilast N-oxide in two phase III trials (DERMIS-1, n = 245; DERMIS-2, n = 250) of roflumilast cream 0.3% for 8 weeks was assessed at Weeks 4 and 8.

RESULTS

Bioavailability of roflumilast cream 0.3% after topical administration was 1.5%. Unlike after oral dosing, the plasma concentration-time curve was flat, with a peak-to-trough ratio of 1.2. Roflumilast N-oxide concentrations were eightfold higher than roflumilast concentrations. The t_½ in adult patients was 4.0 days for roflumilast and 4.6 days for roflumilast N-oxide following the last dose administered. Steady state was reached by Day 15. Concentrations of roflumilast in skin were, on average, 126- and 61.8-fold higher than corresponding mean plasma C_trough following administration of roflumilast cream 0.15% and 0.5% daily for 28 days. Roflumilast N-oxide was quantifiable in only one skin sample (N = 27). Following 8 weeks of treatment in DERMIS-1, mean plasma C_trough of roflumilast was 1.78 ng/mL, and 9.86 ng/mL for roflumilast N-oxide. In DERMIS-2, mean plasma C_trough was 1.72 ng/mL and 10.2 ng/mL, respectively. In the maximal usage study (mean BSA: 27.5%), eight patients (30.8%) experienced adverse events (AEs) and all were mild or moderate, with no reports of diarrhea, headache, insomnia, or application-site pain; no patients discontinued treatment due to an AE.

CONCLUSION

Topical administration of roflumilast cream 0.3% results in concentrations in skin 126- and 61.8-fold higher relative to plasma, which are much higher than expected to be achievable with oral dosing. PDE4 inhibition in the skin is likely due to roflumilast as compared with its active metabolite, as there is no significant conversion to roflumilast N-oxide in the skin. Consistent with reservoir formation and retention of drug in the stratum corneum, roflumilast is slowly released from the skin (t_½ 4 days) and peak-to-trough ratio is 1.2.

CLINICALTRIALS

GOV IDENTIFIERS

NCT04279119, NCT03392168, NCT04211363, NCT04211389.

Effect of Roflumilast Cream vs Vehicle Cream on Chronic Plaque Psoriasis: The DERMIS-1 and DERMIS-2 Randomized Clinical Trials

IMPORTANCE

Once-daily roflumilast cream, 0.3%, a potent phosphodiesterase 4 inhibitor, demonstrated efficacy and was well tolerated in a phase 2b trial of patients with psoriasis.

OBJECTIVE

To evaluate the efficacy of roflumilast cream, 0.3%, applied once daily for 8 weeks in 2 trials of patients with plaque psoriasis.

DESIGN, SETTING, AND PARTICIPANTS

Two phase 3, randomized, double-blind, controlled, multicenter trials (DERMIS-1 [trial 1; n = 439] and DERMIS-2 [trial 2; n = 442]) were conducted at 40 centers (trial 1) and 39 centers (trial 2) in the US and Canada between December 9, 2019, and November 16, 2020, and between December 9, 2019, and November 23, 2020, respectively. Patients aged 2 years or older with plaque psoriasis involving 2% to 20% of body surface area were enrolled. The dates of final follow-up were November 20, 2020, and November 23, 2020, for trial 1 and trial 2, respectively.

INTERVENTIONS

Patients were randomized 2:1 to receive roflumilast cream, 0.3% (trial 1: n = 286; trial 2: n = 290), or vehicle cream (trial 1: n = 153; trial 2: n = 152) once daily for 8 weeks.

MAIN OUTCOMES AND MEASURES

The primary efficacy end point was Investigator Global Assessment (IGA) success (clear or almost clear status plus ≥2-grade improvement from baseline [score range, 0-4]) at week 8, analyzed using a Cochran-Mantel-Haenszel test stratified by site, baseline IGA score, and intertriginous involvement. There were 9 secondary outcomes, including intertriginous IGA success, 75% reduction in Psoriasis Area and Severity Index (PASI) score, and Worst Itch Numeric Rating Scale score of 4 or higher at baseline achieving 4-point reduction (WI-NRS success) at week 8 (scale: 0 [no itch] to 10 [worst imaginable itch]; minimum clinically important difference, 4 points).

RESULTS

Among 881 participants (mean age, 47.5 years; 320 [36.3%] female), mean IGA scores in trial 1 were 2.9 [SD, 0.52] for roflumilast and 2.9 [SD, 0.45] for vehicle and in trial 2 were 2.9 [SD, 0.48] for roflumilast and 2.9 [SD, 0.47]) for vehicle. Statistically significantly greater percentages of roflumilast-treated patients than vehicle-treated patients had IGA success at week 8 (trial 1: 42.4% vs 6.1%; difference, 39.6% [95% CI, 32.3%-46.9%]; trial 2: 37.5% vs 6.9%; difference, 28.9% [95% CI, 20.8%-36.9%]; P < .001 for both). Of 9 secondary end points, statistically significant differences favoring roflumilast vs vehicle were observed for 8 in trial 1 and 9 in trial 2, including intertriginous IGA success (71.2% vs 13.8%; difference, 66.5% [95% CI, 47.1%-85.8%] and 68.1% vs 18.5%; difference, 51.6% [95% CI, 29.3%-73.8%]; P < .001 for both), 75% reduction in PASI score (41.6% vs 7.6%; difference, 36.1% [95% CI, 28.5%-43.8%] and 39.0% vs 5.3%; difference, 32.4% [95% CI, 24.9%-39.8%]; P < .001 for both), WI-NRS success (67.5% vs 26.8%; difference, 42.6% [95% CI, 31.3%-53.8%] and 69.4% vs 35.6%; difference, 30.2% [95% CI, 18.2%-42.2%]; P < .001 for both). The incidence of treatment-emergent adverse events was 25.2% with roflumilast vs 23.5% with vehicle in trial 1 and 25.9% with roflumilast vs 18.4% with vehicle in trial 2. The incidence of serious adverse events was 0.7% with roflumilast vs 0.7% with vehicle in trial 1 and 0% with roflumilast vs 0.7% with vehicle in trial 2.

CONCLUSIONS AND RELEVANCE

Among patients with chronic plaque psoriasis, treatment with roflumilast cream, 0.3%, compared with vehicle cream resulted in better clinical status at 8 weeks. Further research is needed to assess efficacy compared with other active treatments and to assess longer-term efficacy and safety.

TRIAL REGISTRATION

ClinicalTrials.gov Identifiers: NCT04211363, NCT04211389.

Current emerging and investigational drugs for the treatment of chronic hand eczema

INTRODUCTION

: Chronic hand eczema (CHE) is a highly prevalent, burdensome condition associated with functional impairment. Currently, topical therapeutics are the mainstay of CHE management. However, many cases are refractory to existing topical therapeutics, and the few existing systemic options are often limited in efficacy and by their side effect profiles.

AREAS COVERED

: Following a brief overview of CHE pathogenesis and existing treatments, this review will outline the mechanisms and available data on emerging and investigational drugs currently being studied in clinical trials for the treatment of CHE.

EXPERT OPINION

: Immunomodulatory drugs such as topical and systemic JAK inhibitors and Th2-targeting antibodies such as dupilumab are currently under investigation for CHE treatment, with early promise. Management of CHE will likely move toward more targeted treatments through clinical trials and away from broad immunosuppressants such as cyclosporine and methotrexate, which have previously been investigated for CHE and have more side effects. In coming years, CHE patients may benefit from a wider range of both topical and systemic therapeutics that target immune pathways relevant to the various CHE subtypes.

Boron-Containing heterocycles as promising pharmacological agents

The incorporation of the "magic" boron atom has been established as an important new strategy in the field of medicinal chemistry as boron compounds have been shown to form various bonds with their biological targets. Currently, a number of boron-based drugs (e.g. bortezomib, crisaborole, and tavaborole) have been FDA approved and are in the clinic, and several other boron-containing compounds are in clinical trials. Boron-based heterocycles have an incredible potential in the ongoing quest for new therapeutic agents owing to their plethora of biological activities and useful pharmacokinetic profiles. The present perspective is intended to review the pharmacological applications of boron-based heterocycles that have been published. We have classified these compounds into groups exhibiting shared pharmacological activities and discussed their corresponding biological targets focusing mainly on the most potent therapeutic compounds.

The Boron Advantage: The Evolution and Diversification of Boron’s Applications in Medicinal Chemistry

In this review, the history of boron’s early use in drugs, and the history of the use of boron functional groups in medicinal chemistry applications are discussed. This includes diazaborines, boronic acids, benzoxaboroles, boron clusters, and carboranes. Furthermore, critical developments from these functional groups are highlighted along with recent developments, which exemplify potential prospects. Lastly, the application of boron in the form of a prodrug, softdrug, and as a nanocarrier are discussed to showcase boron’s emergence into new and exciting fields. Overall, we emphasize the evolution of organoboron therapeutic agents as privileged structures in medicinal chemistry and outline the impact that boron has had on drug discovery and development.

Clinical Implication of Phosphodiesterase-4-Inhibition

The pleiotropic function of 3',5'-cyclic adenosine monophosphate (cAMP)-dependent pathways in health and disease led to the development of pharmacological phosphodiesterase inhibitors (PDE-I) to attenuate cAMP degradation. While there are many isotypes of PDE, a predominant role of PDE4 is to regulate fundamental functions, including endothelial and epithelial barrier stability, modulation of inflammatory responses and cognitive and/or mood functions. This makes the use of PDE4-I an interesting tool for various therapeutic approaches. However, due to the presence of PDE4 in many tissues, there is a significant danger for serious side effects. Based on this, the aim of this review is to provide a comprehensive overview of the approaches and effects of PDE4-I for different therapeutic applications. In summary, despite many obstacles to use of PDE4-I for different therapeutic approaches, the current data warrant future research to utilize the therapeutic potential of phosphodiesterase 4 inhibition.

High Efficiency In Vitro Wound Healing of Dictyophora indusiata Extracts via Anti-Inflammatory and Collagen Stimulating (MMP-2 Inhibition) Mechanisms

Dictyophora indusiata or Phallus indusiatus is widely used as not only traditional medicine, functional foods, but also, skin care agents. Biological activities of the fruiting body from D. indusiata were widely reported, while the studies on the application of immature bamboo mushroom extracts were limited especially in the wound healing effect. Wound healing process composed of 4 stages including hemostasis, inflammation, proliferation, and remodelling. This study divided the egg stage of bamboo mushroom into 3 parts: peel and green mixture (PGW), core (CW), and whole mushroom (WW). Then, aqueous extracts were investigated for their nucleotide sequencing, biological compound contents, and wound healing effect. The anti-inflammatory determination via the levels of cytokine releasing from macrophages, and the collagen stimulation activity on fibroblasts by matrix metalloproteinase-2 (MMP-2) inhibitory activity were determined to serve for the wound healing process promotion in the stage 2–4 (wound inflammation, proliferation, and remodelling of the skin). All D. indusiata extracts showed good antioxidant potential, significantly anti-inflammatory activity in the decreasing of the nitric oxide (NO), interleukin-1 (IL-1), interleukin-1 (IL-6), and tumour necrosis factor-α (TNF-α) secretion from macrophage cells (p < 0.05), and the effective collagen stimulation via MMP-2 inhibition. In particular, CW extract containing high content of catechin (68.761 ± 0.010 mg/g extract) which could significantly suppress NO secretion (0.06 ± 0.02 µmol/L) better than the standard anti-inflammatory drug diclofenac (0.12 ± 0.02 µmol/L) and their MMP-2 inhibition (41.33 ± 9.44%) was comparable to L-ascorbic acid (50.65 ± 2.53%). These findings support that CW of D. indusiata could be an essential natural active ingredient for skin wound healing pharmaceutical products.

Ribes nigrum Leaf Extract Preferentially Inhibits IFN-γ-Mediated Inflammation in HaCaT Keratinocytes

Ribes nigrum L. (blackcurrant) leaf extracts, due to high levels of flavonols and anthocyanins, have been shown to exhibit beneficial effects in inflammatory diseases. However, whereas their traditional use has been investigated and validated in several models of inflammation and oxidative stress, the possible impact on skin disorders is still largely unknown. The purpose of this work was to elucidate the effects of R. nigrum leaf extract (RNLE) on keratinocyte-derived inflammatory mediators, elicited by a Th1 or Th2 cytokine milieu. HaCaT cells were challenged with TNF-α, either alone or in combination with the costimulatory cytokines IFN-γ or IL-4, and the release of proinflammatory cytokines and mediators (IL-8, IL-6, s-ICAM-1, and TSLP) was evaluated. The results showed that RNLE preferentially interferes with IFN-γ signaling, demonstrating only negligible activity on TNF-α or IL-4. This effect was attributed to flavonols, which might also account for the ability of RNLE to impair TNF-α/IL-4-induced TSLP release in a cAMP-independent manner. These results suggest that RNLE could have an antiallergic effect mediated in keratinocytes via mechanisms beyond histamine involvement. In conclusion, the discovery of RNLE preferential activity against IFN-γ-mediated inflammation suggests potential selectivity against Th1 type response and the possible use in Th1 inflammatory diseases.

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.

Progress in the medicinal chemistry of organoboron compounds

The review aims to draw attention to the latest advances in the organoboron chemistry and therapeutic use of organoboron compounds. The synthetic strategies towards boron-containing compounds with proven in vitro and/or in vivo biological activities, including derivatives of boronic acids, benzoxaboroles, benzoxaborines and benzodiazaborines, are summarized. Approaches to the synthesis of hybrid structures containing an organoboron moiety as one of the pharmacophores are considered, and the effect of this modification on the pharmacological activity of the initial molecules is analyzed. On the basis of analysis of the published data, the most promising areas of research in the field of organoboron compounds are identified, including the latest methods of synthesis, modification and design of effective therapeutic agents.

The bibliography includes 246 references.

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.

Translational Relevance of Mouse Models of Atopic Dermatitis

The complexity of atopic dermatitis (AD) continues to present a challenge in the appropriate selection of a mouse model because no single murine model completely recapitulates all aspects of human AD. This has been further complicated by recent evidence of the distinct AD endotypes that are dictated by unique patterns of inflammation involving Th1, Th2, Th17, and Th22 axes. A review of currently used mouse models demonstrates that while all AD mouse models consistently exhibit Th2 inflammation, only some demonstrate concomitant Th17 and/or Th22 induction. As the current understanding of the pathogenic contributions of these unique endotypes and their potential therapeutic roles expands, ongoing efforts to maximize a given mouse model’s homology with human AD necessitates a close evaluation of its distinct immunological signature.

DRM02, a novel phosphodiesterase-4 inhibitor with cutaneous anti-inflammatory activity

Chronic inflammatory skin disorders are frequently associated with impaired skin barrier function. Selective phosphodiesterase-4 (PDE4) inhibition constitutes an effective therapeutic strategy for the treatment of inflammatory skin diseases. We now report the pharmacological anti-inflammatory profile of DRM02, a novel pyrazolylbenzothiazole derivative with selective in vitro inhibitory activity toward PDE4 isoforms A, B and D. DRM02 treatment of cultured primary human and mouse epidermal keratinocytes interfered with pro-inflammatory cytokine production elicited by interleukin-1α and tumor necrosis factor-α. Similarly, DRM02 inhibited the production of pro-inflammatory cytokines by human peripheral blood mononuclear cells ex vivo and cultured THP-1 monocyte-like cells, with IC₅₀ values of 0.6-14 µM. These anti-inflammatory properties of DRM02 were associated with dose-dependent repression of nuclear factor-κB (NF-κB) transcriptional activity. In skin inflammation in vivo mouse models, topically applied DRM02 inhibited the acute response to phorbol ester and induced Th2-type contact hypersensitivity reactivity. Further, DRM02 also decreased cutaneous clinical changes and expression of Th17 immune pathway cytokines in a mouse model of psoriasis evoked by repeated topical imiquimod application. Thus, the overall pharmacological profiling of the PDE4 inhibitor DRM02 has revealed its potential as a topical therapy for inflammatory skin disorders and restoration of skin homeostasis.

Off-Label Therapeutic Potential of Crisaborole

Crisaborole, a topical phosphodiesterase-4 inhibitor, was recently approved in 2016 for the treatment of mild to moderate atopic dermatitis in adults and children greater than 2 years of age. Since that time, several case reports and a small randomized controlled trial have been published regarding the off-label use of crisaborole for the treatment of other inflammatory dermatologic disorders. This paper reviews the current, albeit limited, evidence for off-label use of crisaborole for psoriasis, seborrheic dermatitis, vitiligo, and inflammatory linear verrucous epidermal nevus. Additional potential therapeutic uses for crisaborole are also postulated, based on its mechanism of action. Future studies are required to elucidate the full therapeutic potential of crisaborole; however, it is a welcome addition to the current nonsteroid topical treatments for inflammatory dermatologic disease.

Antibacterial Activity and Mode of Action of a Sulfonamide-Based Class of Oxaborole Leucyl-tRNA-Synthetase Inhibitors

Benzoxaboroles are a class of boron-containing compounds with a broad range of biological activities. A subset of benzoxaboroles have antimicrobial activity due primarily to their ability to inhibit leucyl-tRNA synthetase (LeuRS) via the oxaborole tRNA-trapping mechanism, which involves the formation of a stable tRNA^Leu-benzoxaborole adduct in which the boron atom interacts with the 2'- and 3'-oxygen atoms of the terminal 3' tRNA adenosine. We sought to identify other antibacterial targets for this promising class of compounds by means of mode-of-action studies, and we selected a nitrophenyl sulfonamide based oxaborole (PT638) as a probe molecule because it had potent antibacterial activity (MIC of 0.4 μg/mL against methicillin-resistant Staphylococcus aureus) but did not inhibit LeuRS (IC₅₀ > 100 μM). Analogues of PT638 were synthesized to explore the importance of the sulfonamide linker and the impact of altering the functionalization of the phenyl ring. These structure-activity-relationship studies revealed that the nitro substituent was essential for activity. To identify the target for PT638, we raised resistant strains of S. aureus, and whole-genome sequencing revealed mutations in leuRS, suggesting that the target for this compound was indeed LeuRS, despite the lack of enzyme inhibition. Subsequent analysis of PT638 metabolism demonstrated that bacterial nitroreductases readily converted this compound into the amino analogue, which inhibited LeuRS with an IC₅₀ of 3.0 ± 1.2 μM, demonstrating that PT638 is thus a prodrug.

Boron in drug design: Recent advances in the development of new therapeutic agents

Advances in the field of boron chemistry have expanded the application of this element in Medicinal Chemistry. Boron-containing compounds represent a new class for medicinal chemists to use in their drug designs. Bortezomib (Velcade^®), a dipeptide boronic acid approved by the FDA in 2003 for treatment of multiple myeloma, paved the way for the discovery of new boron-containing compounds. After its approval, two other boron-containing compounds have been approved, tavaborole (Kerydin^®) for the treatment of onychomicosis and crisaborole (Eucrisa^®) for the treatment of mild to moderate atopic dermatitis. A number of boron-containing compounds have been described and evaluated for a plethora of therapeutic applications. The present review is intended to highlight the recent advances related to boron-containing compounds and their therapeutic applications. Here, we focused only in those most biologically active compounds with proven in vitro and/or in vivo efficacy in the therapeutic area published in the last years.

Effects of boron-containing compounds on immune responses: review and patenting trends

INTRODUCTION

Boron-containing compounds induce effects on immune responses. Such effects are interesting to the biomedical field for the development of therapeutic tools to modulate the immune system.

AREAS COVERED

The scope of BCC use to modify immune responses is expanding, mainly with regard to inflammatory diseases. The information was organized to demonstrate the breadth of reported effects. BCCs act as modulators of innate and adaptive immunity, with the former including regulation of cluster differentiation and cytokine production. In addition, BCCs exert effects on inflammation induced by infectious and noninfectious agents, and there are also reports regarding their effects on mechanisms involving hypersensitivity and transplants. Finally, the authors discuss the beneficial effects of BCCs on pathologies involving various targets and mechanisms.

EXPERT OPINION

Some BCCs are currently used as drugs in humans. The mechanisms by which these BCCs modulate immune responses, as well as the required structure-activity relationship for each observed mechanism of action, should be clarified. The former will allow for the development of improved immunomodulatory drugs with extensive applications in medicine. Patenting trends involve claims concerning the synthesis and actions of identified molecules with a defined profile regarding cytokines, cell differentiation, proliferation, and antibody production.