Pathophysiology of Prurigo Nodularis: Neuroimmune Dysregulation and the Role of Type 2 Inflammation.

Prurigo nodularis (PN) is a chronic, inflammatory skin condition characterized by multiple, intensely pruritic, distinctive nodular lesions. Subsequent scratching can further intensify the pruritus, culminating in a self-reinforcing itch-scratch cycle, which drives lesion development. The latest data indicate dysregulation of the neuroimmune axis in PN pathogenesis, including the involvement of sensory neurons, key effector immune cells, proinflammatory cytokines, dermal fibroblasts, and pruritogens. In this review, we highlight evidence supporting the role of type 2 immune axis dysregulation in driving the clinical presentation of PN and discuss how related signaling pathways may offer effective therapeutic targets to control PN signs and symptoms.

The Skin Acid Mantle: An Update on Skin pH.

The acid mantle concept refers to the buffer system located in the upper stratum corneum of the skin. By sustaining an acidic environment, the acid mantle contributes to the regulation of the microbiome, structural stability, and inflammation. Skin pH is pivotal in maintaining the integrity of the epidermal barrier. Shifts in pH can disrupt barrier properties, and recent studies have emphasized its impact on dermatologic disease processes. This review explores the complex relationship of mechanisms through which skin pH impacts dermatologic pathologies. Furthermore, we highlight the promising potential of pH-targeted therapies for advancing the management of skin conditions.

Patients with Moderate-to-Severe Atopic Dermatitis Maintain Stable Response with No or Minimal Fluctuations with 1 Year of Lebrikizumab Treatment.

INTRODUCTION: Lebrikizumab is a novel monoclonal antibody with established efficacy in patients with moderate-to-severe atopic dermatitis (AD) in multiple Phase 3 trials. One of the ultimate treatment goals for patients with moderate-to-severe AD is to achieve stable disease control without concern for planning future life events. METHODS: In ADvocate1 and ADvocate2, lebrikizumab-treated patients meeting the protocol-defined response criteria at Week 16 were re-randomized 2:2:1 to receive lebrikizumab every 2 weeks (Q2W), lebrikizumab every 4 weeks (Q4W), or placebo Q2W (lebrikizumab withdrawal) for 36 additional weeks. In this post hoc analysis, we evaluated the proportions of patients with no or minimal fluctuations of efficacy during the 36-week maintenance period and plotted individual patient trajectories. We defined no or minimal fluctuations as achieving and maintaining the defined endpoint (≥ 75% improvement in the Eczema Area and Severity Index [EASI 75], ≥ 90% improvement in EASI, Pruritus Numeric Rating Scale [NRS] ≥ 4-point improvement, or Pruritus NRS ≥ 3-point improvement) for ≥ 80% of the study visits. If patients used rescue medication, discontinued treatment, or transferred to the escape arm, data collected at or after the event were imputed as non-response. RESULTS: The proportions of lebrikizumab responders who maintained EASI 75 with no or minimal fluctuations were 70.8% (lebrikizumab Q2W), 71.2% (lebrikizumab Q4W), and 60.0% (lebrikizumab withdrawal). Of the patients with baseline Pruritus NRS ≥ 4 and who achieved ≥ 4-point improvement at Week 16, 66.1% (lebrikizumab Q2W), 62.7% (lebrikizumab Q4W), and 55.2% (lebrikizumab withdrawal) maintained ≥ 4-point Pruritus NRS improvement with no or minimal fluctuations. CONCLUSIONS: Patients who met the response criteria at Week 16 and continued treatment with lebrikizumab Q2W or Q4W demonstrated a stable response with no or minimal fluctuations of efficacy in measures of skin and itch up to Week 52. CLINICAL TRIAL REGISTRATION: NCT04146363 (ADvocate1) and NCT04178967 (ADvocate2).

Atopic dermatitis, also known as atopic eczema (or just eczema), is a common skin disease that causes itchy, dry skin. Patients with eczema are often unsure of when disease flares will happen, even while receiving treatment. In two global studies, ADvocate1 and ADvocate2, lebrikizumab improved the signs and symptoms of moderate-to-severe eczema after 16 weeks of treatment. Most of these patients also saw improvement up to 52 weeks. We wanted to know if patients continued to feel better between Week 16 and Week 52. Patients who responded to lebrikizumab after 16 weeks were given lebrikizumab every 2 weeks, lebrikizumab every 4 weeks, or placebo every 2 weeks. We tested how many patients experienced stable response to therapy, which we said was maintaining the same level of improvement on skin signs and itch symptoms for at least 80% of study visits from Week 16 to Week 52. In patients treated with lebrikizumab every 2 weeks or every 4 weeks, we saw that about seven of every ten patients maintained a stable response in skin improvement and about six of every ten patients maintained stable response in itch symptoms. In patients who stopped lebrikizumab therapy, six out of every ten patients maintained a stable skin improvement and more than five of every ten patients maintained a stable improvement in itch symptoms. In ADvocate1 and ADvocate2, most lebrikizumab-treated patients showed a stable response over time on skin and itch with dosing every 2 weeks or every 4 weeks.

Dupilumab improves pruritus and skin lesions in patients with prurigo nodularis: Pooled results from 2 phase 3 trials (LIBERTY-PN PRIME and PRIME2).

Background: Phase 3 PRIME/PRIME2 trials independently demonstrated efficacy and an acceptable safety profile of dupilumab adults with moderate-to-severe prurigo nodularis. Objective: To obtain a more precise estimate of onset and magnitude of treatment effect using PRIME/PRIME2 pooled data. Methods: In PRIME/PRIME2, patients were randomized to dupilumab or placebo for 24 weeks. Pooled analysis assessed proportion of patients achieving clinically meaningful improvement in itch, clear/almost-clear skin, or both; at weeks 12 and 24; overall and by demographic subgroups and changes from baseline to week 24 in symptoms, signs, and quality of life. Results: Patients receiving dupilumab (n = 153) vs placebo (n = 158) experienced significant improvements in all tested endpoints. At week 24, 90 (58.8%) dupilumab-treated vs 30 (19.0%) placebo-treated patients achieved clinically meaningful improvement in itch, 71 (46.4%) vs 27 (17.1%) clear/almost clear skin, and 54 (35.3%) vs 14 (8.9%) achieved both (P < .0001 for all). Treatment benefits were independent of baseline demographics. Safety to week 36 was generally consistent with the known dupilumab safety profile. Limitations: On-treatment data limited to 24 weeks. Conclusions: Pooled analysis confirmed improvements reported in individual trials and revealed earlier effect onset in itch and skin pain. Dupilumab treatment showed benefits across demographics.

Stable Response and Sustained Improvement of Itch and Sleep Symptoms in Patients with Atopic Dermatitis Treated with Lebrikizumab over 52 Weeks.

BACKGROUND: Lebrikizumab demonstrated significant improvement versus placebo for measures of skin clearance and patient-reported outcomes at weeks 16 and 52 in patients with moderate-to-severe atopic dermatitis (AD). We report the sustained impact of lebrikizumab monotherapy, over 52 weeks and between visits, on the frequency of itch and sleep loss symptoms, as assessed by Patient-Oriented Eczema Measure (POEM), in patients with moderate-to-severe AD. METHODS: In ADvocate1 and ADvocate2, Week-16 lebrikizumab responders (EASI75 or IGA 0/1 with ≥ 2-point improvement and without rescue medication) were randomized to lebrikizumab every 2 weeks (Q2W), every 4 weeks (Q4W), or placebo for 36 weeks. This pooled analysis reports improvement from Week 16 to 52 in patients achieving POEM response 0 (no days) or 1 (1-2 days) for Items 1 (itch) and 2 (sleep disturbance) for the lebrikizumab Q2W and Q4W treatment arms. Observed (excluding data collected after treatment discontinuation, rescue medication use, or patient transfer to escape arm) results were reported. RESULTS: At Week 16, for lebrikizumab Q2W and Q4W, 35.9% (n = 37/103) and 39.3% (n = 42/107) of patients responded 0 or 1 to Item 1 of POEM (Itch) and 12.6% (n = 13/103) and 12.1% (n = 13/107) responded 0. A total of 66.0% (n = 68/103) and 72.6% (n = 77/106) of patients responded 0 or 1 to Item 2 of POEM (Sleep) and 37.9% (n = 39/103) and 44.3% (n = 47/106) responded 0, respectively. By Week 52, for lebrikizumab Q2W and Q4W, 44.6% (n = 29/65) and 48.0% (n = 36/75) responded 0 or 1 to Item 1 of POEM (Itch), and 21.5% (n = 14/65) and 18.7% (n = 14/75) of patients responded 0. A total of 83.1% (n = 54/65) and 78.4% (n = 58/74) responded 0 or 1 to Item 2 of POEM (Sleep), and 67.7% (n = 44/65) and 59.5% (n = 44/74) responded 0, respectively. CONCLUSION: Weekly POEM responses for itch and sleep disturbance remained stable between doses and visits, and continued to improve from Week 16 through 52, in lebrikizumab-treated patients, demonstrating consistent improvement over time for key AD symptoms. TRIAL REGISTRATION NUMBERS: ADvocate1 (NCT04146363) and ADvocate2 (NCT04178967).

Unmet needs in treating itch: reaching beyond eczema.

PURPOSE: Pruritus is an unpleasant sensation that creates the urge to scratch. In many chronic conditions, relentless pruritus and scratching perpetuates a vicious itch-scratch cycle. Uncontrolled itch can detrimentally affect quality of life and may lead to sleep disturbance, impaired concentration, financial burden, and psychological suffering. Recent strides have been made to develop guidelines and investigate new therapies to treat some of the most common severely pruritic conditions, however, a large group of diseases remains underrecognized and undertreated. The purpose of this article is to provide a comprehensive review of the challenges hindering the treatment of pruritus. METHODS: An online search was performed using PubMed, Web of Science, Google Scholar, and ClinicalTrials.gov from 1994 to 2024. Included studies were summarized and assessed for quality and relevance in treating pruritus. RESULTS: Several barriers to treating pruritus emerged, including variable presentation, objective measurement of itch, and identifying therapeutic targets. Itch associated with autoimmune conditions, connective tissue diseases, genodermatoses, cutaneous T-cell lymphoma, and pruritus of unknown origin were among the etiologies with the greatest unmet needs. CONCLUSION: Treating pruritus poses many challenges and there are many itchy conditions that have no yet been addressed. There is an urgent need for large-scale controlled studies to investigate potential targets for these conditions and novel therapies.

International study on prevalence of itch: examining the role of itch as a major global public health problem.

BACKGROUND: Very few studies evaluated the global prevalence of pruritus. OBJECTIVE: To assess its prevalence according to age, gender, ethnicity, and geographic regions. METHODS: An international cross-sectional study was conducted in 20 countries from January to April 2023. Participants were asked to complete a questionnaire on sociodemographics, confirm the presence or absence of a skin disease in the last 12 months and the presence or absence of pruritus in the last 7 days. RESULTS: The studied sample included 50552 individuals. The worldwide prevalence of pruritus was 39.8%. The age group ≥65 had the highest prevalence (43.3%). The prevalence was 40.7% among women and 38.9% among men (p<0.001). There was no significant difference between ethnicities (p=0.14). Compared to North America (41.6%), the prevalence of pruritus was significantly lower in Europe (35.9%, p<0.001), Australia (38.4%, p=0.017), East Asia (40.2%, p=0.04), and Latin America (36.5%, p<0.001), and higher in Africa (45,7%, p=0.007). No significant difference was found with the Middle East (40.2%, p=0.36). The prevalence was 40.3% in developed countries and 38.7% in BRICS countries 40.7% (p<10-3). LIMITATIONS: No information about the severity or type (acute, chronic) of pruritus. CONCLUSION: Global prevalence of pruritus revealed age, gender, and geographic region differences, with no ethnic differences.

Treatment of Brachioradial Pruritus: A Tertiary Center Retrospective Analysis.

This retrospective study investigates the efficacy of 2 treatment regimens, pregabalin alone versus pregabalin combined with ketamine, amitriptyline, and lidocaine cream, in reducing itch in patients with brachioradial pruritus at a tertiary care center. Electronic medical records of 64 brachioradial pruritus patients seen at the University of Miami Itch Center were analyzed. A significant reduction in itch scores was seen with both treatments, with no significant difference between the groups. A small number of patients experienced adverse effects, including drowsiness and weight gain with pregabalin and skin irritation with ketamine, amitriptyline, and lidocaine cream. Ultimately, our findings underscore the potential of utilizing combined therapy for difficult-to-treat brachioradial pruritus cases and implementing individualized approaches for managing neuropathic pruritus. Further controlled clinical trials are needed to establish optimal treatment protocols.

Worst Itch Numeric Rating Scale for Prurigo Nodularis: A Secondary Analysis of 2 Randomized Clinical Trials.

Importance: Prurigo nodularis (PN) is a debilitating skin disease characterized by the hallmark symptom of chronic itch; the intensity of itch in PN was assessed using the Worst Itch Numeric Rating Scale (WI-NRS) to evaluate the primary efficacy end point of 2 recent phase 3 studies of dupilumab treatment for PN. Objective: To validate the psychometric properties and to determine the clinically meaningful improvement threshold for WI-NRS in patients with moderate to severe PN. Design, Setting, and Participants: In this secondary analysis of the PRIME and PRIME2 trials, content validity of WI-NRS was assessed through in-depth patient interviews. Psychometric assessments used pooled data from masked, intention-to-treat (ITT) patients with PN from randomized, double-masked, and placebo-controlled studies. Psychometric assessments included test-retest reliability, construct validity, known-groups validity, and sensitivity to change in adult patients with moderate-to-severe PN. Thresholds for meaningful within-patient improvement in the WI-NRS score were determined using anchor and distribution-based approaches. Data were analyzed after completion of each study, December 2019 to November 2021 for PRIME and January 2020 to August 2021 for PRIME2. Exposures: Dupilumab (300 mg) or placebo subcutaneously every 2 weeks for 24 weeks. Main outcomes and measures: WI-NRS score at specified time points up to 24 weeks after randomization. Results: A total of 20 patients were included across the 2 studies (mean [SD] age, 49.3 [17.2] years; 11 female [55%]); 311 patients were included in the pooled intention-to-treat analysis (mean [SD] age, 49.5 [16.1] years; 203 female [65.3%]). The WI-NRS questions (20 of 20 patients), recall period (19 of 20 patients), and response scale (20 of 20 patients) were easy to understand and relevant for patients with PN. Adequate test-retest reliability was observed between screening and baseline (intraclass correlation coefficient = 0.72, using Patient Global Impression of Severity [PGIS] to define stable patients). Convergent and discriminant validity was supported by moderate to strong correlations (absolute r range = 0.34-0.73) with other conceptually related measures and weaker correlations (absolute r range = 0.06-0.32) with less-related measures, respectively. WI-NRS was sensitive to change, as demonstrated by differences in change from baseline among groups (per PGIS change and PGI of Change [PGIC]). Using anchor-based approach with PGIS and PGIC, the clinically meaningful improvement threshold was 4 points (range, 3.0-4.5), which was also supported by distribution-based methods. Conclusion and Relevance: This study found that WI-NRS may be a fit-for-purpose instrument to support efficacy end points measuring the intensity of itching in adults with PN. Trial Registration: NCT04183335 (PRIME) and NCT04202679 (PRIME2).

A Practical Approach to Diagnosing and Managing Chronic Spontaneous Urticaria.

Chronic spontaneous urticaria (CSU) is an unpredictable inflammatory skin condition characterized by the spontaneous onset of itchy wheals, angioedema, or both, which occurs for longer than 6 weeks overall. Despite the relatively straightforward diagnostic algorithm for CSU, relying primarily on a detailed medical history and only limited laboratory tests, patients often wait years to be diagnosed, with many cycling through different healthcare practitioners before a diagnosis is made. Even then, current treatment options for CSU are limited, with approximately half of patients resistant to standard-of-care second-generation antihistamines at standard or higher doses. As such, there is an unmet need for improved, streamlined management for patients with CSU. Here, we review the evidence-based diagnostic algorithm for CSU, consider the required steps of the diagnostic workup, and provide practical, real-world advice on the management of CSU to improve the timely diagnosis and care of patients with this debilitating disease.

Chronic Pruritus: A Review.

Importance: Chronic pruritus, defined as itch experienced for 6 weeks or longer, affects approximately 22% of people in their lifetime. Approximately 1% of physician visits are for the chief concern of chronic pruritus. Chronic pruritus is associated with adverse outcomes, including impaired sleep and reduced quality of life. Observations: Chronic pruritus can be categorized by etiology into inflammatory, neuropathic, or a combination of inflammatory and neuropathic pruritus. Chronic pruritus is due to inflammation in approximately 60% of patients and may be caused by eczema, psoriasis, or seborrheic dermatitis. Chronic pruritus is due to a neuropathic or mixed etiology in approximately 25% of patients. Neuropathic causes of chronic pruritus include postherpetic neuralgia and notalgia paresthetica and are typically due to localized or generalized nerve dysregulation. Approximately 15% of people with chronic pruritus have other causes including systemic diseases with secondary itch, such as uremic pruritus and cholestatic pruritus, medication-induced pruritus such as pruritus due to immunotherapy, and infectious etiologies such as tinea corporis and scabies. When few primary changes are present, a thorough history, review of symptoms, and laboratory evaluation should be performed, particularly for people with chronic pruritus lasting less than 1 year. Clinicians should consider the following tests: complete blood cell count, complete metabolic panel, and thyroid function testing to evaluate for hematologic malignancy, liver disease, kidney disease, or thyroid disease. First-line treatment for inflammatory chronic pruritus includes topical anti-inflammatory therapies such as hydrocortisone (2.5%), triamcinolone (0.1%), or tacrolimus ointment. Approximately 10% of patients do not respond to topical therapies. In these patients, referral to dermatology and systemic oral or injectable treatments such as dupilumab or methotrexate may be considered. When no underlying systemic disease associated with pruritus is identified, patients are likely to have neuropathic chronic pruritus or mixed etiology such as chronic pruritus of unknown origin. In these patients, neuropathic topical treatments such as menthol, pramoxine, or lidocaine can be used either alone or in combination with immunomodulatory agents such as topical steroids. Other effective therapies for neuropathic pruritus include gabapentin, antidepressants such as sertraline or doxepin, or opioid receptor agonist/antagonists such as naltrexone or butorphanol. Conclusions and Relevance: Chronic pruritus can adversely affect quality of life and can be categorized into inflammatory, neuropathic, or a combined etiology. First-line therapies are topical steroids for inflammatory causes, such as hydrocortisone (2.5%) or triamcinolone (0.1%); topical neuropathic agents for neuropathic causes, such as menthol or pramoxine; and combinations of these therapies for mixed etiologies of chronic pruritus.

Responder analysis using clinically meaningful thresholds: Post hoc analyses from randomized dupilumab clinical trials in patients with prurigo nodularis.

BACKGROUND: Prurigo nodularis (PN) is an intensely pruritic disease characterized by itchy nodules on the trunk/extremities; it is often accompanied by skin pain and sleep disruption with negative impacts on the quality of life (QoL). The patient-reported outcome (PRO) instruments, Worst Itch-Numeric Rating Scale (WI-NRS), Skin Pain-NRS, Sleep-NRS and Dermatology Life Quality Index (DLQI) have been psychometrically validated and the clinically meaningful within-patient improvement thresholds (responder definition) have been established through data pooled from the two Phase-3 trials (PRIME, NCT04183335 and PRIME2, NCT04202679) of dupilumab in adults with PN uncontrolled on topical therapies. OBJECTIVES: To estimate the proportion of dupilumab-treated patients (vs. placebo) achieving clinically meaningful improvement in itch, skin pain, sleep and QoL, either alone or in combination, from the data pooled from PRIME and PRIME2 trials. METHODS: The patient-level data pooled from the two Phase-3 trials (N = 311) were used for this post hoc analysis. Thresholds of clinically meaningful within-patient improvement in PRO instrument scores from baseline at Week 24 used for defining responders were 4 (WI-NRS and Skin Pain-NRS), 2 (Sleep-NRS) and 9 points (DLQI). The proportion of dupilumab-treated patients, versus placebo, achieving the thresholds, and the time taken to achieve the thresholds were evaluated for the individual and combination of PROs. RESULTS: Responder rates were significantly higher with dupilumab, versus placebo at Week 24 for WI-NRS (58.8% vs. 19.0%, p < 0.0001), Skin Pain-NRS (49.7% vs. 20.9%, p < 0.0001), Sleep-NRS (42.5% vs. 23.4%, p < 0.0001) and DLQI (64.7% vs. 22.8%, p < 0.0001). Proportion of patients achieving simultaneous improvement in symptoms and QoL (24.8% vs. 6.3%, p < 0.0001) were significantly higher in dupilumab-treated patients versus placebo. The time needed for achieving clinically meaningful improvement in symptoms were significantly lower in dupilumab-treated patients, versus placebo. CONCLUSIONS: Significantly greater proportion of dupilumab-treated patients with PN, versus placebo, demonstrated clinically meaningful improvements in PRO measures of symptoms and QoL.

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.

Current and emerging drugs for the treatment of pruritus: an update of the literature.

INTRODUCTION: Pruritus, particularly in its chronic form, often imposes significant suffering and reductions in patients' quality of life. The pathophysiology of itch is varied depending on disease context, creating opportunities for unique drug development and multimodal therapy. AREAS COVERED: The purpose of this article is to provide an update of the literature regarding current and emerging therapeutics in itch. We review the multitudes of drug targets available and corresponding drugs that have shown efficacy in clinical trials, with a particular emphasis on phase 2 and 3 trials and beyond. Broadly, these targets include therapies directed against type 2 inflammation (i.e. Th2 cytokines, JAK/STAT, lipid mediators, T-cell mediators, and other enzymes and receptors) and neural receptors and targets (i.e. PARs, TRP channels, opioid receptors, MRGPRs, GABA receptors, and cannabinoid receptors). EXPERT OPINION: Therapeutics for itch are emerging at a remarkable pace, and we are entering an era with more and more specialized therapies. Increasingly, these treatments are able to relieve itch beyond their effect on inflammation by directly targeting the neurosensory system.