Successful Treatment of Hypoglycemia With Alpelisib in Pediatric Patients With PIK3CA-Related Overgrowth Spectrum.

Activating mutations in the PIK3CA gene, causing phosphoinositide 3-kinase (PI3K) hyperactivation, are rare causes of hypoglycemia. We report the novel use of alpelisib (a PI3K inhibitor) for the treatment of hypoketotic, hypoinsulinemic hypoglycemia in 2 children with PIK3CA-related overgrowth spectrum (PROS). Patient 1 was a 7-month-old girl who presented with a hypoglycemic seizure. Despite nutritional management including continuous feeds, she continued to have frequent hypoglycemia. At age 2.8 years, alpelisib was started at 50 mg daily and titrated to 100 mg daily. She was weaned off nocturnal continuous feeds by 8 months. She developed colitis when the alpelisib dose was increased to 125 mg, but this resolved with a dose decrease and medical management. At age 5.3 years, she was doing well with rare hypoglycemia. Her accelerated growth stabilized. Patient 2 was a 3-year-old boy who developed hypoglycemia in early infancy. Alpelisib 50 mg daily was started due to recurrent hypoglycemia despite nutritional management. He came off continuous feeds after 4 months, with decreased hypoglycemia frequency. At age 4.5 years, he had not experienced side effects from treatment. In conclusion, alpelisib appears to be effective in decreasing PROS-related hypoglycemia frequency and severity and should be considered for refractory hypoglycemia in this condition.

Challenges in the care of individuals with severe primary insulin-like growth factor-I deficiency (SPIGFD): an international, multi-stakeholder perspective.

BACKGROUND: Severe primary insulin-like growth factor-I (IGF-I) deficiency (SPIGFD) is a rare growth disorder characterized by short stature (standard deviation score [SDS] ≤ 3.0), low circulating concentrations of IGF-I (SDS ≤ 3.0), and normal or elevated concentrations of growth hormone (GH). Laron syndrome is the best characterized form of SPIGFD, caused by a defect in the GH receptor (GHR) gene. However, awareness of SPIGFD remains low, and individuals living with SPIGFD continue to face challenges associated with diagnosis, treatment and care. OBJECTIVE: To gather perspectives on the key challenges for individuals and families living with SPIGFD through a multi-stakeholder approach. By highlighting critical gaps in the awareness, diagnosis, and management of SPIGFD, this report aims to provide recommendations to improve care for people affected by SPIGFD globally. METHODS: An international group of clinical experts, researchers, and patient and caregiver representatives from the SPIGFD community participated in a virtual, half-day meeting to discuss key unmet needs and opportunities to improve the care of people living with SPIGFD. RESULTS: As a rare disorder, limited awareness and understanding of SPIGFD amongst healthcare professionals (HCPs) poses significant challenges in the diagnosis and treatment of those affected. Patients often face difficulties associated with receiving a formal diagnosis, delayed treatment initiation and limited access to appropriate therapy. This has a considerable impact on the physical health and quality of life for patients, highlighting a need for more education and clearer guidance for HCPs. Support from patient advocacy groups is valuable in helping patients and their families to find appropriate care. However, there remains a need to better understand the burden that SPIGFD has on individuals beyond height, including the impact on physical, emotional, and social wellbeing. CONCLUSIONS: To address the challenges faced by individuals and families affected by SPIGFD, greater awareness of SPIGFD is needed within the healthcare community, and a consensus on best practice in the care of individuals affected by this condition. Continued efforts are also needed at a global level to challenge existing perceptions around SPIGFD, and identify solutions that promote equitable access to appropriate care. Medical writing support was industry-sponsored.

Model-Based Analysis of IGF-I Response, Dosing, and Monitoring for Once-Weekly Somapacitan in Children With GH Deficiency.

Context: Growth hormone (GH) replacement therapy improves longitudinal growth and adult height in children with GH deficiency (GHD). GH stimulates insulin-like growth factor (IGF)-I release, the biomarker used for monitoring GH activity during treatment. Objective: This study aims to provide model-based insights into the dose-IGF-I responses of once-weekly somapacitan, a novel long-acting GH, compared with daily GH in children with GHD. Methods: Analyses included dosing information and 1473 pharmacokinetic samples from 210 somapacitan-treated pediatric patients with GHD across 3 trials, including phase 1 (NCT01973244), phase 2 (NCT02616562; REAL 3), and phase 3 (NCT03811535; REAL 4), as well as 1381 IGF-I samples from 186 patients with GHD treated with somapacitan in REAL 3 and REAL 4. Pharmacokinetic/pharmacodynamic modeling to characterize somapacitan dose-IGF-I response and predict the response to dosing day changes. Results: Relationships were established between somapacitan dose, exposure, change from baseline IGF-I SD score (SDS), and height velocity (HV). A linear model permitted the development of a tool to calculate estimated average weekly IGF-I exposure from a single IGF-I sample obtained at any time within the somapacitan dosing interval at steady state. In practice, the use of this tool requires knowledge of somapacitan injection timing relative to IGF-I sample collection timing. IGF-I SDS simulations support flexible dosing day changes while maintaining at least 4 days between doses. Conclusion: We characterized the dose-IGF-I response of somapacitan in children with GHD. To support physicians in IGF-I monitoring, we present a practical guide about expected weekly average IGF-I concentrations in these patients and provide insights on dosing day flexibility.

Using change in predicted adult height during GnRH agonist treatment for individualized treatment decisions in girls with central precocious puberty.

OBJECTIVES: It is important to understand what variables influence change in predicted adult height (PAH) throughout GnRHa treatment for central precocious puberty (CPP) to individualize treatment decisions and optimize care. METHODS: Changes in PAH, chronological age (CA), bone age (BA), BA/CA, and height velocity (HV) were evaluated in girls with CPP throughout treatment with leuprolide acetate (n=77). A second analysis focused on changes in the 3 years preceding the first observed BA of ≥12 years. Relationships were characterized using plot inspection and linear mixed-effects analyses. Association between treatment duration and last assessed PAH was examined using multiple linear regression models. RESULTS: BA/CA and HV showed a nonlinear change during treatment, with the largest changes and improvement in PAH observed in the first 6-18 months. Rate of BA advancement tended to decrease more slowly in girls initiating treatment at a younger BA. On-treatment change in PAH was predicted by concurrent BA/CA change, HV, and BA, as well as CA at treatment initiation. Last assessed PAH was positively associated with longer treatment durations (primary/exploratory models cut-offs of ≥33/≥55 months). CONCLUSIONS: These findings support individualized monitoring during GnRHa treatment. Initial response should be interpreted with caution until 6-18 months after treatment initiation and failure should not be assumed based on continued bone maturation in girls starting therapy at a younger age. Treatment cessation should not be automatically based on a diminishing change in PAH or HV, as ongoing treatment may result in continued increase or maintenance of PAH.

Evolution and Future of Growth Plate Therapeutics.

BACKGROUND: Longitudinal bone growth is regulated by multiple endocrine signals (e.g., growth hormone, insulin-like growth factor I, estrogen, and androgen) and local factors (e.g., fibroblast growth factors and their receptors and the C-natriuretic peptide/natriuretic peptide receptor-B pathway). SUMMARY: Abnormalities in both endocrine and local regulation of growth plate physiology cause many disorders of human skeletal growth. Knowledge of these pathways creates therapeutic potential for sustaining or even augmenting linear growth. Key Message: During the past 4 decades, advances in understanding growth plate physiology have been accompanied by development and implementation of growth-promoting treatments that have progressed in both efficacy and specificity of action. This paper reviews the history and continuing evolution of growth plate therapeutics.

Developmental Adaptive Immune Defects Associated with STAT5B Deficiency in Three Young Siblings.

Patients with rare homozygous mutations in signal transducer and activator of transcription 5B (STAT5B) develop immunodeficiency resulting in chronic eczema, chronic infections, autoimmunity, and chronic lung disease. STAT5B-deficient patients are typically diagnosed in the teenage years, limiting our understanding of the development of associated phenotypic immune abnormalities. We report the first detailed chronological account of post-natal immune dysfunction associated with STAT5B deficiency in humans. Annual immunophenotyping of three siblings carrying a novel homozygous nonsense mutation in STAT5B was carried out over 4 years between the ages of 7 months to 8 years. All three siblings demonstrated consistent B cell hyperactivity including elevated IgE levels and autoantibody production, associated with diagnoses of atopy and autoimmunity. Total T cell levels in each sibling remained normal, with regulatory T cells decreasing in the oldest sibling. Interestingly, a skewing toward memory T cells was identified, with the greatest changes in CD8+ effector memory T cells. These results suggest an importance of STAT5B in B cell function and naïve versus memory T cell survival. Progressive dysregulation of FOXP3+ regulatory T cells and CD8+ memory T cell subsets reveal a crucial role of STAT5B in T cell homeostasis. The early diagnosis and focused immune evaluations of these three young STAT5B-deficient siblings support an important role of STAT5B in adaptive immune development and function.

The continuum between GH deficiency and GH insensitivity in children.

The continuum of growth hormone (GH)-IGF-I axis defects extends from severe to mild GH deficiency, through short stature disorders of undefined aetiology, to GH insensitivity disorders which can also be mild or severe. This group of defects comprises a spectrum of endocrine, biochemical, phenotypic and genetic abnormalities. The extreme cases are generally easily diagnosed because they conform to well-studied phenotypes with recognised biochemical features. The milder cases of both GH deficiency and GH insensitivity are less well defined and also overlap with the group of short stature conditions, labelled as idiopathic short stature (ISS). In this review the continuum model, which plots GH sensitivity against GH secretion, will be discussed. Defects causing GH deficiency and GH insensitivity will be described, together with the use of a diagnostic algorithm, designed to aid investigation and categorisation of these defects. The continuum will also be discussed in the context of growth-promoting endocrine therapy.

Progression of Vasculopathy in Young Individuals with Turner Syndrome.

Vasculopathy has been identified in young individuals with Turner syndrome (TS). No studies in young individuals with TS have investigated whether this vasculopathy progresses over time. The objective of this study is to describe the changes in vasculopathy over time in a cohort of young individuals with TS. Repeat ultrasound and SphygmoCor CPV® (AtCor Medical) measurements of carotid thickness and peripheral arterial stiffness were performed. Vascular measurements were compared at baseline and follow-up. Follow-up measurements were also compared to historical lean (L) and obese (O) age-, race-, and sex-matched non-TS controls. Thirty-five individuals with TS were studied at a mean age of 19.4 years (range, 13.9-27.5). Mean time to follow-up was 7.2 years (range, 7.1-7.8). Carotid intima media thickness increased by 0.03 ± 0.07 mm (p < 0.01) over time, but was less than L and O controls at follow-up. Pulse wave velocity carotid-femoral increased by 0.51 ± 0.86 m/s (p < 0.01) over time, but was similar to L and less than O controls at follow-up. Augmentation index (AIx) remained unchanged (p = 0.09) over time, but was significantly higher at follow-up than both control groups (p < 0.01 for both). There were no identified differences between 45,X and other TS genotypes. We demonstrate evidence of vascular thickening and stiffening over 7 years in a cohort of young individuals with TS, as well as a persistently increased augmentation index compared to L and O non-TS controls. It is unclear whether the increase in vascular structure and function are related to normal aging or if TS is a risk factor. Higher body mass index seems to be a risk factor. Early estrogen replacement and longer exposure to growth hormone therapy need to be further explored as potential protective factors.

Recombinant human insulin-like growth factor-1 therapy for 6 months improves growth but not motor function in boys with Duchenne muscular dystrophy.

INTRODUCTION: Recombinant human insulin-like growth factor-1 (rhIGF-1) is a growth factor and has anabolic effects on muscle. We investigated whether rhIGF-1 therapy: 1) improves or preserves muscle function; and 2) improves growth in boys with Duchenne muscular dystrophy (DMD). METHODS: In this study we compared prepubescent, ambulatory, glucocorticoid-treated boys with DMD (n = 17) vs controls (glucocorticoid therapy only, n = 21) in a 6-month-long, prospective, randomized, controlled trial of subcutaneous rhIGF-1 therapy. The primary outcome was 6-minute walk distance (6MWD). Secondary outcomes included height velocity (HV), change in height standard deviation score (ΔHtSDS), motor function, cardiopulmonary function, body composition, insulin sensitivity, quality of life, and safety. RESULTS: Change in 6MWD was similar between groups (rhIGF-1 vs controls [mean ± SD]: 3.4 ± 32.4 vs -5.1 ± 50.2 meters, P = .53). Treated subjects grew more than controls (HV: 6.5 ± 1.7 vs 3.3 ± 1.3 cm/year, P < .0001; 6-month ΔHtSDS: 0.25, P < .0001). Lean mass and insulin sensitivity increased in treated subjects. DISCUSSION: In boys with DMD, 6 months of rhIGF-1 therapy did not change motor function, but it improved linear growth.

Diagnosis, Genetics, and Therapy of Short Stature in Children: A Growth Hormone Research Society International Perspective.

The Growth Hormone Research Society (GRS) convened a Workshop in March 2019 to evaluate the diagnosis and therapy of short stature in children. Forty-six international experts participated at the invitation of GRS including clinicians, basic scientists, and representatives from regulatory agencies and the pharmaceutical industry. Following plenary presentations addressing the current diagnosis and therapy of short stature in children, breakout groups discussed questions produced in advance by the planning committee and reconvened to share the group reports. A writing team assembled one document that was subsequently discussed and revised by participants. Participants from regulatory agencies and pharmaceutical companies were not part of the writing process. Short stature is the most common reason for referral to the pediatric endocrinologist. History, physical examination, and auxology remain the most important methods for understanding the reasons for the short stature. While some long-standing topics of controversy continue to generate debate, including in whom, and how, to perform and interpret growth hormone stimulation tests, new research areas are changing the clinical landscape, such as the genetics of short stature, selection of patients for genetic testing, and interpretation of genetic tests in the clinical setting. What dose of growth hormone to start, how to adjust the dose, and how to identify and manage a suboptimal response are still topics to debate. Additional areas that are expected to transform the growth field include the development of long-acting growth hormone preparations and other new therapeutics and diagnostics that may increase adult height or aid in the diagnosis of growth hormone deficiency.

Nonclassical GH Insensitivity: Characterization of Mild Abnormalities of GH Action.

GH insensitivity (GHI) presents in childhood with growth failure and in its severe form is associated with extreme short stature and dysmorphic and metabolic abnormalities. In recent years, the clinical, biochemical, and genetic characteristics of GHI and other overlapping short stature syndromes have rapidly expanded. This can be attributed to advancing genetic techniques and a greater awareness of this group of disorders. We review this important spectrum of defects, which present with phenotypes at the milder end of the GHI continuum. We discuss their clinical, biochemical, and genetic characteristics. The objective of this review is to clarify the definition, identification, and investigation of this clinically relevant group of growth defects. We also review the therapeutic challenges of mild GHI.

Toward More Targeted and Cost-Effective Gonadotropin-Releasing Hormone Analog Treatment in Girls with Central Precocious Puberty.

The use of gonadotropin-releasing hormone analogs (GnRHa) for the treatment of central precocious puberty (CPP), especially in girls, has increased rapidly in recent years. In the context of a secular trend towards earlier puberty onset, many girls now treated for CPP are healthy children experiencing puberty onset within the early end of the normal range. Justifications for GnRHa treatment include the preservation of adult height (AH) potential and the alleviation of presumed distress of early maturation and menarche. With a case of a family requesting treatment for an 8-year-old girl in early puberty as a background, studies of the effect of untreated CPP and of GnRHa treatment of CPP on AH are reviewed. In addition, the limited evidence relating CPP to significant psychological distress - in part due to early menses, and for the amelioration of such distress by GnRHa treatment - is discussed. Taken together, current information suggests that for girls with mildly early onset of puberty (ages 7-9 years), an informed assent discussion with the family should include the consideration of reassurance and observation for many girls who might otherwise receive 2-4 years of GnRHa treatment for a poorly defined benefit and at a cost of at least $20-30,000 per year.

Craniosynostosis as the Presenting Feature of X-linked Hypophosphatemic Rickets.

Craniosynostosis is the premature closure of cranial sutures. Primary, or congenital, craniosynostosis is often sporadic but may be associated with genetic or chromosomal abnormalities. Secondary craniosynostosis presents after gestation, and can occur in metabolic bone diseases, including rickets. We describe the first reported cases of primary craniosynostosis in 2 unrelated, term infants with X-linked hypophosphatemic rickets (XLH). The diagnosis of XLH in both patients was confirmed by genetic testing. At the time craniosynostosis was detected, the patient in the first case did not have any other clinical features of XLH. The second patient developed clinical findings of craniosynostosis, followed by rickets. These are the earliest reported cases of craniosynostosis in XLH and demonstrate that craniosynostosis may be a presenting feature of this disease.

Bone fragility in Turner syndrome: Fracture prevalence and risk factors determined by a national patient survey.

OBJECTIVE: Osteoporosis is considered a comorbidity of adult women with Turner syndrome (TS). Limited data are available on fracture prevalence in girls and women with this diagnosis. We aimed to determine the prevalence of fractures in individuals with TS in the United States and identify risk factors for fracture. DESIGN: Girls and women with TS were invited to participate in an anonymous, self-report, national survey from November 2016 to March 2017. Non-TS controls were obtained through direct contacts of TS participants. RESULTS: During childhood (0-12 years), adolescence (13-25 years) and young adulthood (26-45 years), there was no difference between TS and controls in fracture prevalence. Girls and women with TS were more likely to report upper extremity fractures, whereas controls were more likely to report phalangeal fractures. Older women (>45 years) with TS were more likely to fracture than non-TS controls (P = .01). Balance problems were more common in individuals with TS than controls (26.5% vs 14.8%, P = .0006). In TS, those reporting balance problems were 54% more likely to have a prior fracture than those without balance problems (OR=1.54, 95% CI 1.03, 2.30), even after controlling for age. There was no significant association between balance problems and fractures among controls. CONCLUSIONS: In a nationwide survey, there was no difference in fracture prevalence in younger women with TS compared with controls. However, the location of fractures differed. After controlling for age, impaired balance was associated with an increased fracture risk in TS and may be an underrecognized risk factor for fracture in this population.

Estrogen Replacement in Turner Syndrome: Literature Review and Practical Considerations.

Context: Most girls with Turner syndrome (TS) have hypergonadotropic hypogonadism and need hormonal replacement for induction of puberty and then for maintaining secondary sex characteristics, attaining peak bone mass, and uterine growth. The optimal estrogen replacement regimen is still being studied. Evidence Acquisition: We conducted a systematic search of PubMed for studies related to TS and puberty. Evidence Synthesis: The goals of replacement are to mimic normal timing and progression of physical and social development while minimizing risks. Treatment should begin at age 11 to 12 years, with dose increases over 2 to 3 years. Initiation with low-dose estradiol (E2) is crucial to preserve growth potential. Delaying estrogen replacement may be deleterious to bone and uterine health. For adults who have undergone pubertal development, we suggest transdermal estrogen and oral progestin and discuss other approaches. We discuss linear growth, lipids, liver function, blood pressure, neurocognition, socialization, and bone and uterine health as related to hormonal replacement. Conclusion: Evidence supports the effectiveness of starting pubertal estrogen replacement with low-dose transdermal E2. When transdermal E2 is unavailable or the patient prefers, evidence supports use of oral micronized E2 or an intramuscular preparation. Only when these are unavailable should ethinyl E2 be prescribed. We recommend against the use of conjugated estrogens. Once progestin is added, many women prefer the ease of use of a pill containing both an estrogen and a progestin. The risks and benefits of different types of preparations, with examples, are discussed.

Turner Syndrome: Diagnostic and Management Considerations for Perinatal Clinicians.

The perinatal clinician needs to understand certain essential concepts when encountering an infant with a suspected or confirmed diagnosis of Turner syndrome. This article describes the key clinical features that should prompt testing, the appropriate diagnostic workup, the necessary screening required after diagnosis, and how to best approach family counseling.

Current best practice in the management of Turner syndrome.

Turner syndrome (TS) is characterized by partial or complete loss of the second X-chromosome in phenotypic females resulting in a constellation of clinical findings that may include lymphedema, cardiac anomalies, short stature, primary ovarian failure and neurocognitive difficulties. Optimizing health care delivery is important to enable these individuals achieve their full potential. We review the current best practice management recommendations for individuals with TS focusing on the latest consensus opinion in regard to genetic diagnosis, treatment of short stature, estrogen supplementation, addressing psychosocial issues, as well screening for other comorbidities. A multidisciplinary approach and a well-planned transition to adult follow-up care will improve health care delivery significantly for this population.

Novel Dominant-Negative GH Receptor Mutations Expands the Spectrum of GHI and IGF-I Deficiency.

CONTEXT: Autosomal-recessive mutations in the growth hormone receptor (GHR) are the most common causes for primary growth hormone insensitivity (GHI) syndrome with classical GHI phenotypically characterized by severe short stature and marked insulin-like growth factor (IGF)-I deficiency. We report three families with dominant-negative heterozygous mutations in the intracellular domain of the GHR causing a nonclassical GHI phenotype. OBJECTIVE: To determine if the identified GHR heterozygous variants exert potential dominant-negative effects and are the cause for the GHI phenotype in our patients. RESULTS: All three mutations (c.964dupG, c.920_921insTCTCAAAGATTACA, and c.945+2T>C) are predicted to result in frameshift and early protein termination. In vitro functional analysis of variants c.964dupG and c.920_921insTCTCAAAGATTACA (c.920_921ins14) suggests that these variants are expressed as truncated proteins and, when coexpressed with wild-type GHR, mimicking the heterozygous state in our patients, exert dominant-negative effects. Additionally, we provide evidence that a combination therapy of recombinant human growth hormone (rhGH) and rhIGF-I improved linear growth to within normal range for one of our previously reported patients with a characterized, dominant-negative GHR (c.899dupC) mutation. CONCLUSION: Dominant-negative GHR mutations are causal of the mild GHI with substantial growth failure observed in our patients. Heterozygous defects in the intracellular domain of GHR should, therefore, be considered in cases of idiopathic short stature and IGF-I deficiency. Combination therapy of rhGH and rhIGF-I improved growth in one of our patients.