Model-Informed Drug Development Approach Supporting Approval of Adalimumab (HUMIRA) in Adolescent Patients with Hidradenitis Suppurativa: a Regulatory Perspective

Role of Clinical Pharmacology in Diversity and Inclusion in Global Drug Development: Current Practices and Industry Perspectives: White Paper

The 2022 United States Food and Drug Administration (US FDA) draft guidance on diversity plan (DP), which will be implemented through the Diversity Action Plans by December 2025, under the 21st Century Cures Act, marks a pivotal effort by the FDA to ensure that registrational studies adequately reflect the target patient populations based on diversity in demographics and baseline characteristics. This white paper represents the culminated efforts of the International Consortium of Quality and Innovation (IQ) Diversity and Inclusion (D&I) Working Group (WG) to assess the implementation of the draft FDA guidance by members of the IQ consortium in the discipline of clinical pharmacology (CP). This article describes current practices in the industry and emphasizes the tools and techniques of quantitative pharmacology that can be applied to support the inclusion of a diverse population during global drug development, to support diversity and inclusion of underrepresented patient populations, in multiregional clinical trials (MRCTs). It outlines strategic and technical recommendations to integrate demographics, including age, sex/gender, race/ethnicity, and comorbidities, in multiregional phase III registrational studies, through the application of quantitative pharmacology. Finally, this article discusses the challenges faced during global drug development, which may otherwise limit the enrollment of a broader, potentially diverse population in registrational trials. Based on the outcomes of the IQ survey that provided the current awareness of diversity planning, it is envisioned that in the future, industry efforts in the inclusion of previously underrepresented populations during global drug development will culminate in drug labels that apply to the intended patient populations at the time of new drug application or biologics license application rather than through post-marketing requirements.

Quantitative Systems Pharmacology Models: Potential Tools for Advancing Drug Development for Rare Diseases

Rare diseases, affecting millions globally, present significant drug development challenges. This is due to the limited patient populations and the unique pathophysiology of these diseases, which can make traditional clinical trial designs unfeasible. Quantitative Systems Pharmacology (QSP) models offer a promising approach to expedite drug development, particularly in rare diseases. QSP models provide a mechanistic representation of the disease and drug response in virtual patients that can complement routinely applied empirical modeling and simulation approaches. QSP models can generate digital twins of actual patients and mechanistically simulate the disease progression of rare diseases, accounting for phenotypic heterogeneity. QSP models can also support drug development in various drug modalities, such as gene therapy. Impactful QSP models case studies are presented here to illustrate their value in supporting various aspects of drug development in rare indications. As these QSP model applications continue to mature, there is a growing possibility that they could be more widely integrated into routine drug development steps. This integration could provide a robust framework for addressing some of the inherent challenges in rare disease drug development.

Model-informed drug development in pediatric, pregnancy and geriatric drug development: States of the art and future

The challenges of drug development in pediatric, pregnant and geriatric populations are a worldwide concern shared by regulatory authorities, pharmaceutical companies, and healthcare professionals. Model-informed drug development (MIDD) can integrate and quantify real-world data of physiology, pharmacology, and disease processes by using modeling and simulation techniques to facilitate decision-making in drug development. In this article, we reviewed current MIDD policy updates, reflected on the integrity of physiological data used for MIDD and the effects of physiological changes on the drug PK, as well as summarized current MIDD strategies and applications, so as to present the state of the art of MIDD in pediatric, pregnant and geriatric populations. Some considerations are put forth for the future improvements of MIDD including refining regulatory considerations, improving the integrity of physiological data, applying the emerging technologies, and exploring the application of MIDD in new therapies like gene therapies for special populations.

Biologics and Small Molecule Targeted Therapies for Pediatric Alopecia Areata, Psoriasis, Atopic Dermatitis, and Hidradenitis Suppurativa in the US: A Narrative Review

BACKGROUND

The management of pediatric dermatological conditions such as alopecia areata (AA), psoriasis, atopic dermatitis (AD), and hidradenitis suppurativa (HS) has significantly evolved with the introduction of biologics and small molecule targeted therapies. The advancement in understanding the immunopathogenesis of these chronic skin conditions has led to the development and approval of novel biologics and small molecule therapies. Initially approved by the United States Food and Drug Administration (FDA) for adults, most of these therapies are now being evaluated in clinical trials for safety and efficacy in adolescents and children, expanding new treatment options for pediatric patients. The role of the FDA in drug approval is multifaceted from drug inception, ensuring that research, data, and evidence show that the proposed drug is effective and safe for the intended use.

OBJECTIVE

The goal of this review article is to provide an overview of the recently FDA-approved and potential biologic and oral small molecule therapies in clinical trials for AA, psoriasis, AD, and HS in pediatric patients.

METHODS

The search for this review included keywords in ClinicalTrials.gov, PubMed, and Google Scholar for the latest research and clinical trials relevant to these conditions and treatments without the PRISMA methodology.

RESULTS

For pediatric AA, ritlecitinib is FDA-approved, while baricitinib and updacitinib are in phase 3 clinical trials for pediatric approval. The FDA-approved drugs for pediatric psoriasis include secukinumab, ustekinumab, ixekizumab, etanercept, and apremilast. Other phase 3 clinical trials for pediatric psoriasis include risankizumab, guselkumab, tildrakizumab, brodalumab, and deucravacitinib. For pediatric AD, the FDA-approved drugs are dupilumab, tralokinumab, abrocitinib, and upadacitinib, with many other drugs in phase 3 trials. Adalimumab is an FDA-approved biologic for pediatric HS, with various clinical trials ongoing for adults. The approved biologics and small molecule therapies had higher efficacy and improved safety profiles compared to traditional medications.

CONCLUSIONS

With numerous ongoing trials, the success of these clinical trials could lead to their inclusion in treatment guidelines for these chronic skin conditions. Biologics and small molecule therapies offer new avenues for effective disease management, enabling personalized therapeutic interventions and improving pediatric health outcomes.

Access to dermatologic care and provider impact on hidradenitis suppurativa care: global survey insights

Background

Hidradenitis suppurativa (HS) is an understudied disease, and current HS studies have focused on participants already connected to dermatologic care.

Objective

We surveyed participants in online HS support communities to gain a comprehensive understanding of how provider type impacts HS disease management and the issues individuals with HS face when accessing care.

Methods

From June 13 to June 30, 2021, we administered an anonymous cross-sectional online survey to HS Facebook support group participants who had a self-confirmed diagnosis of HS. Survey items assessed respondent demographics, primary HS provider, and barriers to HS care and pain management. Descriptive analyses are presented.

Results

The survey was viewed 5,168 times and 1,040 surveys met eligibility criteria (20.1%). Survey participants were 97% female and 72% White. Seventy-two percentage resided in the United States and 22% in Europe. Forty-seven percentage reported having a dermatologist as their primary HS provider, 38% reported a nondermatologist, and 15% reported no HS provider. We found that Asian race, full-time employment, private health insurance, and urban setting were each associated with higher rates of having a dermatologist as a primary HS provider. However, 43.7% of those with a dermatologist reported biologic use, as compared with 14.5% with nondermatologist HS providers. Our cohort was notably more severely impacted by comorbid diseases; 55.9% of our cohort had anxiety, 53.6% had depression, and 50.7% had obesity. Overall, 74.2% of our cohort reported experiencing stigma while accessing care for their HS.

Limitations

Participant recruitment via social media platform facilitates recruitment of individuals across the spectrum of healthcare access, but may introduce selection bias and favor well-resourced areas. Self-reported data may be subject to recall bias.

Conclusion

Our study provides unique insights into the characteristics and experiences of individuals with HS across the spectrum of health care access.

A Practical Guide to Using Biologics in Pediatric Dermatology

Psoriasis, hidradenitis suppurativa (HS), atopic dermatitis (AD), and chronic spontaneous urticaria (CSU), are common, immune-mediated, chronic, inflammatory skin diseases that can affect the pediatric population. While there is adequate evidence supporting the use of biologics in pediatric patients, concerns regarding safety and efficacy amongst healthcare providers are not uncommon. However, new emerging evidence in this population highlights the safety of biologic therapy, making it crucial to review and establish a practical guide for their use. This article describes a methodological framework for initiating biologics in the management of pediatric psoriasis, HS, AD, and CSU, with a special focus on baseline work-up, monitoring, dosing, and considerations in this population.

Pediatric model-based dose optimization using a pooled exposure-response safety analysis for nivolumab and nivolumab plus ipilimumab combination in melanoma

An exposure-response (E-R) safety analysis was conducted across adult and pediatric (<18 years) studies to evaluate the potential impact of higher nivolumab and/or ipilimumab exposures in adolescents (≥12 to <18 years) versus adults with melanoma using the approved adult dosing regimens for nivolumab alone or in combination with ipilimumab. Data from 3507 patients across 15 studies were used to examine the relationship between nivolumab-ipilimumab daily average exposure and time to grade 2+ immune-mediated adverse events (gr2+ IMAEs). Results from the E-R safety model showed ipilimumab, but not nivolumab, exposure to be a statistically significant predictor of gr2+ IMAEs. Significant covariates included sex (41% higher risk for women than men), line of therapy (19% higher for first-line than later-line), and treatment setting (26% lower for adjuvant than advanced melanoma). Younger age and lower body weight (BW) were each associated with a lower risk of gr2+ IMAEs (hazard ratio [HR]: 0.830 for 15-year-olds versus 60-year-olds and 0.84 for BW 52 kg versus 75 kg). For adolescents with melanoma treated with nivolumab in the advanced or adjuvant settings, these results are supportive of nivolumab flat dosing regimens for adolescents greater than or equal to 40 kg and BW-based dosing for adolescents less than 40 kg. These results also support adult weight-based dosing regimens for nivolumab plus ipilimumab in adolescents with advanced melanoma. This analysis suggests that although higher exposures are predicted in adolescents with lower weight compared with adults, there is no predicted immune-mediated safety risk when treated with the approved adult dosing of nivolumab with/without ipilimumab.

How to select the initial dose for a pediatric study?

In typical clinical development programs, a new drug is first developed for the adult use. Drugs are often approved for adult use or in the process of obtaining approval in adults in the target indication before pediatric development is initiated. In designing the first pediatric clinical trial, one of the challenges is to select the initial dose to be tested. The ICH E11 R1 guidance advises that chronologic age alone may not always be the most appropriate categorical determinant to define developmental subgroups in pediatric studies. In this manuscript, the approaches to utilize available data in adults related to those factors beyond age to inform the starting dose selection in pediatric drug development are discussed. Practical considerations and approaches are provided for informing pediatric starting dose. Additional considerations to use pre-clinical information are provided in the case when adult information is limited or not available.

Therapeutic Development in Polyarticular Course Juvenile Idiopathic Arthritis: Extrapolation, Dose Selection, and Clinical Trial Design

OBJECTIVE

Stakeholders met to address persistent challenges facing the development of therapeutics for polyarticular juvenile idiopathic arthritis (pJIA), which result in fewer approved therapies for children with pJIA than adults with rheumatoid arthritis (RA) and long lag times from adult RA approval to pediatric labeling. Ensuring that new medications are authorized in a timely manner to meet the needs of JIA patients worldwide is critically important to multiple stakeholders.

METHODS

The Food and Drug Administration in collaboration with the University of Maryland Center for Regulatory Science and Innovation held a public workshop entitled "Accelerating Drug Development for pJIA" on October 2, 2019, to address challenges surrounding access to new medications for children and adolescents with pJIA. Regulatory, academic, and industry stakeholders, as well as patient representatives, participated in the workshop, which consisted of 4 sessions, including panel discussions.

RESULTS

The workshop facilitated broad public discussion of challenges facing the development of pJIA therapeutics, highlighting areas of need and outlining opportunities to expedite development, while underscoring the necessity of close collaboration between all stakeholders, including patients and families.

CONCLUSION

This report summarizes key aspects of the workshop, including the appropriate application of innovative approaches to the development of pJIA therapeutics, including extrapolation, to address current challenges and provide timely access to newer safe and effective treatments. Long-term safety assessment is of pressing concern to stakeholders and cannot be fully extrapolated from adult studies but requires consistent postmarketing long-term follow-up.

Secukinumab in moderate-to-severe hidradenitis suppurativa (SUNSHINE and SUNRISE): week 16 and week 52 results of two identical, multicentre, randomised, placebo-controlled, double-blind phase 3 trials

BACKGROUND

Few therapeutic options are available for patients with moderate-to-severe hidradenitis suppurativa. We aimed to assess the efficacy of secukinumab in patients with moderate-to-severe hidradenitis suppurativa in two randomised trials.

METHODS

SUNSHINE and SUNRISE were identical, multicentre, randomised, placebo-controlled, double-blind phase 3 trials done in 219 primary sites in 40 countries. Patients aged 18 years old or older with the capacity to provide written informed consent and with moderate-to-severe hidradenitis suppurativa (defined as a total of ≥5 inflammatory lesions affecting ≥2 distinct anatomical areas) for at least 1 year were eligible for inclusion. Included patients also agreed to daily use of topical over-the-counter antiseptics on the areas affected by hidradenitis suppurativa lesions while on study treatment. Patients were excluded if they had 20 or more fistulae at baseline, had ongoing active conditions requiring treatment with prohibited medication (eg, systemic biological immunomodulating treatment, live vaccines, or other investigational treatments), or met other exclusion criteria. In both trials, patients were randomly assigned (1:1:1) by means of interactive response technology to receive subcutaneous secukinumab 300 mg every 2 weeks, subcutaneous secukinumab 300 mg every 4 weeks, or subcutaneous placebo all via a 2 mL prefilled syringe in a double-dummy method as per treatment assignment. The primary endpoint was the proportion of patients with a hidradenitis suppurativa clinical response, defined as a decrease in abscess and inflammatory nodule count by 50% or more with no increase in the number of abscesses or in the number of draining fistulae compared with baseline, at week 16, assessed in the overall population. Hidradenitis suppurativa clinical response was calculated based on the number of abscesses, inflammatory nodules, draining fistulae, total fistulae, and other lesions in the hidradenitis suppurativa affected areas. Safety was assessed by evaluating the presence of adverse events and serious adverse events according to common terminology criteria for adverse events, which were coded using Medical Dictionary for Regulatory Activities terminology. Both the SUNSHINE, NCT03713619, and SUNRISE, NCT03713632, trials are registered with ClinicalTrials.gov.

FINDINGS

Between Jan 31, 2019, and June 7, 2021, 676 patients were screened for inclusion in the SUNSHINE trial, of whom 541 (80%; 304 [56%] women and 237 [44%] men; mean age 36·1 years [SD 11·7]) were included in the analysis (181 [33%] in the secukinumab every 2 weeks group, 180 [33%] in the secukinumab every 4 weeks group, and 180 [33%] in the placebo group). Between the same recruitment dates, 687 patients were screened for inclusion in the SUNRISE trial, of whom 543 (79%; 306 [56%] women and 237 [44%] men; mean age 36·3 [11·4] years) were included in the analysis (180 [33%] in the secukinumab every 2 weeks group, 180 [33%] in the secukinumab every 4 weeks group, and 183 [34%] in the placebo group). In the SUNSHINE trial, significantly more patients in the secukinumab every 2 weeks group had a hidradenitis suppurativa clinical response (rounded average number of patients with response in 100 imputations, 81·5 [45%] of 181 patients) compared with the placebo group (60·7 [34%] of 180 patients; odds ratio 1·8 [95% CI 1·1-2·7]; p=0·0070). However, there was no significant difference between the number of patients in the secukinumab every 4 weeks group (75·2 [42%] of 180 patients) and the placebo group (1·5 [1·0-2·3]; p=0·042). Compared with the placebo group (57·1 [31%] of 183 patients), significantly more patients in the secukinumab every 2 weeks group (76·2 [42%] of 180 patients; 1·6 [1·1-2·6]; p=0·015) and the secukinumab every 4 weeks group (83·1 [46%] of 180 patients; 1·9 [1·2-3·0]; p=0·0022) had a hidradenitis suppurativa clinical response in the SUNRISE trial. Patient responses were sustained up to the end of the trials at week 52. The most common adverse event by preferred term up to week 16 was headache in both the SUNSHINE (17 [9%] patients in the secukinumab every 2 weeks group, 20 [11%] in the secukinumab every 4 weeks group, and 14 [8%] in the placebo group) and SUNRISE (21 [12%] patients in the secukinumab every 2 weeks group, 17 [9%] in the secukinumab every 4 weeks group, and 15 [8%] in the placebo group) trials. No study-related deaths were reported up to week 16. The safety profile of secukinumab in both trials was consistent with that previously reported, with no new or unexpected safety findings detected.

INTERPRETATION

When given every 2 weeks, secukinumab was clinically effective at rapidly improving signs and symptoms of hidradenitis suppurativa with a favourable safety profile and with sustained response up to 52 weeks of treatment.

FUNDING

Novartis Pharma.

A cross-sectional study of pediatric hidradenitis suppurativa and the value of the International Hidradenitis Suppurativa Severity Score System (IHS4) as a pediatric clinical trial inclusion criteria

BACKGROUND

Hidradenitis suppurativa (HS) often develops in pediatrics, but few interventional studies include pediatric patients.

OBJECTIVES

This dual analysis of a pediatric HS cohort and typical eligibility criteria in adult trials aims to identify potential patient characteristics and inclusion criteria for future pediatric HS studies.

METHODS

This cross-sectional and descriptive study is based on a prospectively collected data registry from an HS clinic. We also queried 125 HS studies from the Clinicaltrials.gov database and information from 61 interventional systemic HS drug trials was analyzed.

RESULTS

The mean abscess and inflammatory nodule (AN) count in 81 pediatric subjects was 2.3 compared to 5.0 in adults with majority being Hurley stage I (39.5%, 32/81) or II (55.6%, 45/81). Most clinical trials required patients to be Hurley stage II/III with AN count of ≥3.

CONCLUSION

When developing clinical trials for pediatric HS, it is imperative to consider how baseline characteristics impact recruitment and disease assessment. Frequently used eligibility criteria in adult trials may severely limit pediatric recruitment. Although our registry had a large adult sample size, the main limitation of this study was the relatively smaller pediatric sample size.

Review: Role of Model-Informed Drug Development Approaches in the Lifecycle of Drug Development and Regulatory Decision-Making

Model-informed drug development (MIDD) is a powerful approach to support drug development and regulatory review. There is a rich history of MIDD applications at the U.S. Food and Drug Administration (FDA). MIDD applications span across the life cycle of the development of new drugs, generics, and biologic products. In new drug development, MIDD approaches are often applied to inform clinical trial design including dose selection/optimization, aid in the evaluation of critical regulatory review questions such as evidence of effectiveness, and development of policy. In the biopharmaceutics space, we see a trend for increasing role of computational modeling to inform formulation development and help strategize future in vivo studies or lifecycle plans in the post approval setting. As more information and knowledge becomes available pre-approval, quantitative mathematical models are becoming indispensable in supporting generic drug development and approval including complex generic drug products and are expected to help reduce overall time and cost. While the application of MIDD to inform the development of cell and gene therapy products is at an early stage, the potential for future application of MIDD include understanding and quantitative evaluation of information related to biological activity/pharmacodynamics, cell expansion/persistence, transgene expression, immune response, safety, and efficacy. With exciting innovations on the horizon, broader adoption of MIDD is poised to revolutionize drug development for greater patient and societal benefit.

Diagnosing and Managing Hidradenitis Suppurativa in Pediatrics

Hidradenitis suppurativa (HS) is a debilitating chronic inflammatory skin disease that presents as exquisitely tender abscesses, draining fistulae, and sinus tracts. HS can lead to significant impairments in patients' quality of life, especially for children and adolescents who face challenges related to self-esteem and physical and emotional development. Severe long-term physical sequelae of inadequately treated HS include extensive scarring, urogenital strictures, immobility, and squamous cell carcinoma; emotional sequelae include depression, anxiety, and suicidal ideation. Many of the devastating long-term sequelae associated with HS can be prevented with early recognition and proper collaborative management. This article reviews strategies to aid pediatricians in early diagnosis of HS and provides clinical pearls for management and prevention of disease flares. [Pediatr Ann. 2022;51(3):e123-e127.].

Pediatric Hidradenitis Suppurativa: A Cross-Sectional Study on Clinical Features and Treatment Approaches

BACKGROUND

Hidradenitis suppurativa is uncommon in patients of pediatric age, and differentiation with adult-onset disease is controversial. Treatment of pediatric hidradenitis suppurativa is scarcely standardized, and specific guidelines are lacking.

OBJECTIVE

We report the clinical features, relevant risk-factors, comorbidity profile, and treatment patterns of a hospital-based cohort of pediatric hidradenitis suppurativa.

METHODS

In a cross-sectional study data on patients' demographics, disease-specific characteristics, early/pre-pubertal onset of disease, comorbidities, and treatment management were retrieved. Reference population data and clinical data from the national hidradenitis suppurativa disease registry were used for comparison.

RESULTS

From a database of 870 patients with hidradenitis, 71 (15 males and 56 females) patients aged <18 years (mean age: 15.3 years; range 8-17 years), with mild (Hurley I, 45.1%) and moderate-severe disease (Hurley II-III, 54.9%), were retrieved. Smoking (23.9%) and overweight/obese frequencies (59.2%) were higher than reference population standards. Patient's older age at baseline (OR 1.43, 95% CI: 1.01 to 2.02) and higher BMI (OR 1.26, 95% CI: 1.07-1.48) were the only factors associated with moderate-severe disease. Family history and early/pre-pubertal onset of disease were not associated with severity or extent of disease. Sebaceous-follicular comorbid conditions were associated with cigarette smoking (P = .002). Among 81 treatment courses, clindamycin-based and zinc-sulphate-based combination regimens were most frequently used (59.3%). Female preponderance, family history of disease and extensive involvement were significantly different from the general hidradenitis suppurativa population.

CONCLUSIONS

Pediatric hidradenitis suppurativa presents a clinical spectrum comparable to adult-onset disease. Increased preventive measures should target obesity and smoking in this population.

Model-Informed Drug Development in Pediatric Dose Selection

Model-informed drug development (MIDD) has been a powerful and efficient tool applied widely in pediatric drug development due to its ability to integrate and leverage existing knowledge from different sources to narrow knowledge gaps. The dose selection is the most common MIDD application in regulatory submission related to pediatric drug development. This article aims to give an overview of the 3 broad categories of use of MIDD in pediatric dose selection: leveraging from adults to pediatric patients, leveraging from animals to pediatric patients, and integrating mechanism in infants and neonates. Population pharmacokinetic analyses with allometric scaling can reasonably predict the clearance in pediatric patients aged >5 years. A mechanistic-based approach, such as physiologically based pharmacokinetic accounting for ontogeny, or an allometric model with age-dependent exponent, can be applied to select the dose in pediatric patients aged ≤2 years. The exposure-response relationship from adults or from other drugs in the same class may be useful in aiding the pediatric dose selection and benefit-risk assessment. Increasing application and understanding of use of MIDD have contributed greatly to several policy developments in the pediatric field. With the increasing efforts of MIDD under the Prescription Drug User Fee Act VI, bigger impacts of MIDD approaches in pediatric dose selection can be expected. Due to the complexity of model-based analyses, early engagement between drug developers and regulatory agencies to discuss MIDD issues is highly encouraged, as it is expected to increase the efficiency and reduce the uncertainty.

Ixekizumab for the treatment of pediatric patients with moderate to severe plaque psoriasis

Introduction: Ixekizumab (IXE), a high affinity humanized monoclonal antibody that selectively targets interleukin-17A, is approved in the United States (US) and the European Union (EU) for pediatric patients with moderate to severe plaque psoriasis. This review summarizes ixekizumab use in the phase 3, randomized, double-blind, placebo-controlled study in pediatric patients with moderate to severe plaque psoriasis and provides some clinical pearls we have learned after using the drug in the pediatric population for the past 3 years.Areas covered: Review of IXORA-PEDS trial data, general literature review pertaining to the systemic treatment of pediatric psoriasis as well as our clinical experience with IXEExpert opinion: IXE is the only IL17 antagonist for pediatric psoriasis and is a welcome addition to our armamentarium.

Pediatric Dose Selection for Therapeutic Proteins

In selecting optimal dosing regimens in support of the clinical use of monoclonal antibodies and other therapeutic proteins in pediatric indications, the unique pharmacokinetic properties of this class of biologics, as well as the underlying physiologic and pathophysiologic processes and their modulation by childhood growth and development, needs to be appreciated. During drug development, first-in-pediatric dose selection is a capstone event in the pediatric investigation plan that relies heavily on extrapolation of pharmacokinetic and pharmacodynamic data from adult to pediatric populations. It is facilitated by combinations of pharmacometric approaches, including allometry, physiologically based pharmacokinetic modeling, and population pharmacokinetic analyses, although data on reliability and qualification of some of these tools in the context of therapeutic proteins are still limited but emerging. Presented data suggest nonlinear relationships between body weight and both clearance and volume of distribution for therapeutic proteins in pediatric populations, with allometric exponents of 0.75 and 0.8, respectively. For newborns and infants (<1 year), even higher nonlinearity seems to occur. Translation of the quantitative characterization of the pediatric pharmacokinetics of therapeutic proteins into dosing regimens for the drug label requires compromising between precision dosing and clinical practicability, with tiered dosing algorithms based on size or age strata being the currently most frequently applied methodology.

A safety review of biologic therapies for the management of hidradenitis suppurativa and unmet needs

INTRODUCTION

Hidradenitis suppurativa (HS) is a chronic, debilitating inflammatory skin disorder characterized by nodules, abscesses, fistulae, and significant scarring in intertriginous areas rich in apocrine glands. Immunomodulator drugs, including biologics, are a mainstay of treatment for this disease.

AREAS COVERED

This review details the safety profiles of various biologic therapies currently available commercially that have been tried for HS as assessed in clinical trials and observational studies. As the only Food and Drug Administration (FDA)-approved medication for the treatment of moderate-to-severe HS, adalimumab is discussed in the most detail. Additional biologic medications, including tumor necrosis factor α (TNFα) inhibitors, interleukin 1 (IL-1) inhibitors, IL-12 and IL-23 inhibitors, IL-17 inhibitors, and IL-23 inhibitors, are discussed as well. Safety concerns in special populations, including pregnant women and children, are outlined.

EXPERT OPINION

Existing data support excellent short-term and long-term safety profiles for adalimumab, although caution must be taken with use in high-risk patient populations, including those with chronic infections or increased risk of malignancy. Based on their safety data for other indications, additional biologic agents appear safe in HS as well. However, further research is needed to fully understand the safety profiles of these medications in the HS population.

Harnessing formulation and clinical pharmacology knowledge for efficient pediatric drug development: Overview and discussions from M-CERSI pediatric formulation workshop 2019

A pediatric formulation workshop entitled "Pediatric Formulations: Challenges of Today and Strategies for Tomorrow" was held to advance pediatric drug product development efforts in both pre-competitive and competitive environments. The workshop had four main sessions discussing key considerations of Formulation, Analytical, Clinical and Regulatory. This paper focuses on the clinical session of the workshop. It provides an overview of the discussion on the interconnection of pediatric formulation design and development, clinical development strategy and pediatric clinical pharmacology. The success of pediatric drug product development requires collaboration of multi-disciplinary teams across the pharmaceutical industry, consortiums, foundations, academia and global regulatory agencies. Early strategic planning is essential to ensure alignment among major stakeholders of different functional teams. Such an alignment is particularly critical in the collaboration between formulators and clinical pharmacology teams.

Is There a Role for Therapeutic Drug Monitoring in Patients with Hidradenitis Suppurativa on Tumor Necrosis Factor-α Inhibitors?

Tumor necrosis factor-α inhibitors, adalimumab and infliximab, are at the forefront of biologic therapy for the management of moderate-to-severe hidradenitis suppurativa, with adalimumab as currently the only approved medication for this condition. In treating patients, primary or secondary lack of response (also termed suboptimal response) is a major burden for both patients and healthcare systems and is a challenge with biologics in part owing to the development of anti-drug antibodies following treatment. To overcome this, therapeutic drug monitoring may be conducted proactively or reactively to a patient's suboptimal response guided by measurements of trough serum drug concentrations and levels of anti-drug antibodies. While strong evidence to support the utility of therapeutic drug monitoring exists in patients with inflammatory bowel disease, current information is limited in the context of hidradenitis suppurativa. We sought to summarize the available evidence and to present the role of therapeutic drug monitoring and other dose optimization strategies in improving clinical response in patients with hidradenitis suppurativa treated with tumor necrosis factor-α inhibitors.

Anti-TNF Alpha Antibody Humira with pH-dependent Binding Characteristics: A constant-pH Molecular Dynamics, Gaussian Accelerated Molecular Dynamics, and In Vitro Study

Humira is a monoclonal antibody that binds to TNF alpha, inactivates TNF alpha receptors, and inhibits inflammation. Neonatal Fc receptors can mediate the transcytosis of Humira-TNF alpha complex structures and process them toward degradation pathways, which reduces the therapeutic effect of Humira. Allowing the Humira-TNF alpha complex structures to dissociate to Humira and soluble TNF alpha in the early endosome to enable Humira recycling is crucial. We used the cytoplasmic pH (7.4), the early endosomal pH (6.0), and pKa of histidine side chains (6.0-6.4) to mutate the residues of complementarity-determining regions with histidine. Our engineered Humira (W1-Humira) can bind to TNF alpha in plasma at neutral pH and dissociate from the TNF alpha in the endosome at acidic pH. We used the constant-pH molecular dynamics, Gaussian accelerated molecular dynamics, two-dimensional potential mean force profiles, and in vitro methods to investigate the characteristics of W1-Humira. Our results revealed that the proposed Humira can bind TNF alpha with pH-dependent affinity in vitro. The W1-Humira was weaker than wild-type Humira at neutral pH in vitro, and our prediction results were close to the in vitro results. Furthermore, our approach displayed a high accuracy in antibody pH-dependent binding characteristics prediction, which may facilitate antibody drug design. Advancements in computational methods and computing power may further aid in addressing the challenges in antibody drug design.

Hidradenitis suppurativa in pediatric patients

Interest in and research on hidradenitis suppurativa (HS) have increased during the past decade, resulting in expanded knowledge about associated comorbidities and treatment efficacy. Knowledge about pediatric-onset HS is still limited, based on case studies, small case series, and extrapolation from adult studies. With increasing prevalence of childhood obesity, decreasing pubertal age, and increasing awareness of HS, physicians may start encountering younger HS patients. This review presents an updated discussion on the epidemiology, pathophysiology, and associated comorbidities in HS, with a focus on pediatric and adolescent patients. It also suggests recommendations for investigation and treatment based on current evidence.

Biologic therapies for the treatment of hidradenitis suppurativa

Introduction: Hidradenitis suppurativa (HS) is a chronic skin disorder characterized by inflammatory nodules, abscesses, and fistulae. Patients tend to present in young adulthood and are predominantly female. The pathogenesis of HS involves apopilosebaceous gland follicle occlusion and affected areas often occur where this type of gland predominates. Treatment selection depends on HS severity, which is included in different scoring systems. In recent years, biological therapies have been evaluated and used with increasing frequency in moderate-to-severe HS disease.Areas covered: This review focuses on biological therapies for HS as assessed in case reports, case series, and clinical trials. The efficacy, hidradenitis suppurativa scoring systems, and long-term results of these therapies are discussed depending on the studies' endpoints.Expert opinion: Adalimumab is currently the only FDA-approved HS biological therapy. Some patients do not experience treatment efficacy with adalimumab at 40 mg/week, which may result in increasing the dose or seeking other treatments. Infliximab is the next line of HS treatment with demonstrated efficacy. Other biological therapies being studied have demonstrated efficacy in small patient groups, but lack study power. Further studies may provide answers to seeking treatment options for patients who fail to improve on current standard HS treatment.

Long-term safety of adalimumab for patients with moderate-to-severe hidradenitis suppurativa

Introduction: Hidradenitis suppurativa (HS) is a chronic debilitating inflammatory skin disorder that affects regions rich in apocrine glands. Although the etiology of HS is not clear, inflammatory cytokines, like tumor necrosis factor (TNF)-α, participate in pathogenesis. Adalimumab (ADA), a human IgG1 monoclonal antibody that selectively targets TNFα, is the only EMA/FDA-approved biologic agent available for the therapy of moderate-to-severe HS.Areas covered: A comprehensive literature search was conducted to present existing studies with an emphasis on the safety profile of ADA for the treatment of moderate-to-severe HS. ADA is prescribed for more than 15 years for varied indications and has improved the therapeutic outcomes of many diseases. Clinical trials and real-life safety data from ADA administration in HS were presented, with particular attention to special populations, such as children, elderly, and pregnant women.Expert opinion: Existing data advise for limited safety concerns with long-term ADA treatment provided that patients are thoroughly screened for infections, latent tuberculosis, and history of malignancy before the start of treatment.

Management of adolescents with hidradenitis suppurativa

Hidradenitis suppurativa (HS) can have devastating impacts on quality of life (QoL), especially during adolescence when patients face unique challenges related to self-esteem, body-image, and sexual maturation. Many teenage HS patients also experience social challenges related to school, relationships, and employment that may require physician intervention. Strategies for comprehensive management of this special group include addressing low medication adherence, screening for comorbidities, and recommending practical lifestyle modifications to reduce disease flares. Herein, we review the impact of HS on adolescent patients and provide practical recommendations to minimize effects on the adolescent life course.