Characterization and prevalence of severe primary IGF1 deficiency in a large cohort of French children with short stature

Frequency and Predictive Factors of Hypoglycemia in Patients Treated With rhIGF-1: Data From the Eu-IGFD Registry

CONTEXT

The European Increlex® Growth Forum Database (Eu-IGFD) is an ongoing surveillance registry (NCT00903110) established to collect long-term safety and effectiveness data on the use of recombinant human insulin-like growth factor-1 (rhIGF-1, mecasermin, Increlex) for the treatment of children/adolescents with severe primary insulin-like growth factor-1 deficiency (SPIGFD).

OBJECTIVE

This analysis of Eu-IGFD data aimed to identify the frequency and predictive factors for hypoglycemia adverse events (AEs) in children treated with rhIGF-1.

METHODS

Data were collected from December 2008 to May 2021. Logistic regression was performed to identify predictive risk factors for treatment-induced hypoglycemia AEs. Odds ratios (ORs) are presented with 95% CIs for each factor.

RESULTS

In total, 306 patients were enrolled in the registry; 84.6% were diagnosed with SPIGFD. Patients who experienced ≥ 1 hypoglycemia AE (n = 80) compared with those with no hypoglycemia AEs (n = 224) had a lower mean age at treatment start (8.7 years vs 9.8 years), a more frequent diagnosis of Laron syndrome (27.5% vs 10.3%), and a history of hypoglycemia (18.8% vs 4.5%). Prior history of hypoglycemia (OR 0.25; 95% CI: [0.11; 0.61]; P = .002) and Laron syndrome diagnosis (OR 0.36; 95% CI: [0.18; 0.72]; P = .004) predicted future hypoglycemia AEs. Total hypoglycemia AEs per patient per treatment year was 0.11 and total serious hypoglycemia AEs per patient per treatment year was 0.01.

CONCLUSION

Hypoglycemia occurs more frequently in patients with prior history of hypoglycemia and/or Laron syndrome compared with patients without these risk factors, and these patients should be carefully monitored for this AE throughout treatment.

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.

Alterations in Stem Cell Populations in IGF-1 Deficient Pediatric Patients Subjected to Mecasermin (Increlex) Treatment

Pathway involving insulin-like growth factor 1 (IGF-1) plays significant role in growth and development. Crucial role of IGF-1 was discovered inter alia through studies involving deficient patients with short stature, including Laron syndrome individuals. Noteworthy, despite disturbances in proper growth, elevated values for selected stem cell populations were found in IGF-1 deficient patients. Therefore, here we focused on investigating role of these cells-very small embryonic-like (VSEL) and hematopoietic stem cells (HSC), in the pathology. For the first time we performed long-term observation of these populations in response to rhIGF-1 (mecasermin) therapy. Enrolled pediatric subjects with IGF-1 deficiency syndrome were monitored for 4-5 years of rhIGF-1 treatment. Selected stem cells were analyzed in peripheral blood flow cytometrically, together with chemoattractant SDF-1 using immunoenzymatic method. Patients' data were collected for correlation of experimental results with clinical outcome. IGF-1 deficient patients were found to demonstrate initially higher levels of VSEL and HSC compared to healthy controls, with their gradual decrease in response to therapy. These changes were significantly associated with SDF-1 plasma levels. Correlations of VSEL and HSC were also reported in reference to growth-related parameters, and IGF-1 and IGFBP3 values. Noteworthy, rhIGF-1 was shown to efficiently induce development of Laron patients achieving at least proper rate of growth (compared to healthy group) in 80% of subjects. In conclusion, here we provided novel insight into stem cells participation in IGF-1 deficiency in patients. Thus, we demonstrated basis for future studies in context of stem cells and IGF-1 role in growth disturbances.

Pubertal Timing and Growth Dynamics in Children With Severe Primary IGF-1 Deficiency: Results From the European Increlex® Growth Forum Database Registry

BACKGROUND

Puberty is delayed in untreated children and adolescents with severe primary IGF-1 deficiency (SPIGFD); to date, it has not been reported whether recombinant human insulin-like growth factor-1 mecasermin (rhIGF-1) treatment affects this. Pubertal growth outcomes were extracted from the European Increlex^® Growth Forum Database (Eu-IGFD) Registry (NCT00903110).

METHODS

The Eu-IGFD Registry includes children and adolescents aged 2 to 18 years with growth failure associated with SPIGFD who are treated with rhIGF-1. Reported outcomes include: age at last registration of Tanner stage 1 and first registration of Tanner stage 2-5 (T2-T5; based on breast development for girls and genital development for boys, respectively); maximum height velocity during each Tanner stage; and pubertal peak height velocity (PPHV). Data cut-off was 13 May 2019.

RESULTS

This analysis included 213 patients (132 boys and 81 girls). Mean (SD) age at last registration of T1 and first registration of T5 was 13.0 (2.0) and 16.3 (1.6) years, respectively, in boys and 11.6 (1.8) and 14.7 (1.5) years, respectively, in girls. Among patients reaching the end of puberty (25 boys and 11 girls), mean (SD) height SDS increased from -3.7 (1.4) at baseline in the Eu-IGFD Registry to -2.6 (1.4) at T5 in boys and from -3.1 (1.1) to -2.3 (1.5) in girls. Maximum height velocity was observed during T2 in girls and T3 in boys. Median (range) PPHV was 8.0 (0.3-13.0) cm/year in boys and 6.8 (1.3-9.6) cm/year in girls and occurred most frequently during T2. Overall, the adverse events seen in this analysis were in line with the known safety profile of rhIGF-1.

CONCLUSION

Children and adolescents treated with rhIGF-1 for SPIGFD with growth failure experienced an increase in height SDS in prepubertal years compared with baseline. Despite 1.5 years delay in pubertal start and a delayed and slightly lower PPHV, height SDS gain during puberty was maintained.

A synonymous mutation in IGF-1 impacts the transcription and translation process of gene expression

Insulin-like growth factor 1 (IGF-1) is considered to be a crucial gene in the animal development of bone and body size. In this study, a unique synonymous mutation (c.258 A > G) of the IGF-1 gene was modified with an adenine base editor to observe the growth and developmental situation of mutant mice. Significant expression differences and molecular mechanisms among vectors with different alanine synonymous codons were explored. Although modification of a single synonymous codon rarely interferes with animal phenotypes, we observed that the expression and secretion of IGF-1 were different between 8-week-old homozygous (Ho) and wild-type (WT) mice. In addition, the IGF-1 with optimal codon combinations showed a higher expression content than other codon combination modes at both transcription and translation levels and performed proliferation promotion. The gene stability and translation initiation efficiency also changed significantly. Our findings illustrated that the synonymous mutation altered the IGF-1 gene expression in individual mice and suggested that the synonymous mutation affected the IGF-1 expression and biological function through the transcription and translation processes.

Significance of Direct Confirmation of Growth Hormone Insensitivity for the Diagnosis of Primary IGF-I Deficiency

Primary insulin-like growth factor-I (IGF-I) deficiency is a synonym of growth hormone (GH) insensitivity (GHI), however the necessity of direct confirmation of GH resistance by IGF-I generation test (IGF-GT) is discussed. GHI may disturb intrauterine growth, nevertheless short children born small for gestational age (SGA) are treated with GH. We tested the hypothesis that children with appropriate birth size (AGA), height standard deviation score (SDS) <−3.0, GH peak in stimulation tests (stimGH) ≥10.0 µg/L, IGF-I <2.5 centile, and excluded GHI may benefit during GH therapy. The analysis comprised 21 AGA children compared with 6 SGA and 20 GH-deficient ones, with height SDS and IGF-I as in the studied group. All patients were treated with GH up to final height (FH). Height velocity, IGF-I, and IGF binding protein-3 (IGFBP-3) concentrations before and during first year of treatment were assessed. Effectiveness of therapy was better in GHD than in IGF-I deficiency (IGFD), with no significant difference between SGA and AGA groups. All but two AGA children responded well to GH. Pretreatment IGF-I and increase of height velocity (HV) during therapy but not the result of IGF-GT correlated with FH. As most AGA children with apparent severe IGFD benefit during GH therapy, direct confirmation of GHI seems necessary to diagnose true primary IGFD in them.

The Effect of Recombinant Growth Hormone Treatment in Children with Idiopathic Short Stature and Low Insulin-Like Growth Factor-1 Levels

OBJECTIVE

Idiopathic short stature (ISS) constitutes a heterogeneous group of short stature which is not associated with an endocrine or other identifiable cause. Some ISS patients may have varying degrees of insulin-like growth factor-1 (IGF-1) deficiency. Recombinant growth hormone (rGH) treatment has been used by some authors with variable results. Reports on long-term rGH treatment are limited.

METHODS

In this study, 21 slowly growing, non-GH-deficient ISS children who received rGH treatment for 3.62±0.92 years were evaluated at the end of a 5.42±1.67-year follow-up period. The study group included patients with low IGF-1 levels who also responded well to an IGF generation test. The patients were divided into two groups as good responders [height increment >1 standard deviation (SD)] and poor responders (height increment <1 SD) at the end of the follow-up period.

RESULTS

The height of the patients improved from -3.16±0.46 SD score (SDS) to -1.9±0.66 SDS. At the end of the follow-up period, mean height SDS was -1.72. Eleven of the patients showed a good response to treatment. Clinical parameters were essentially similar in the good responders and the poor responders groups. A female preponderance was noted in the good responders group.

CONCLUSION

rGH treatment can safely be used in ISS children. Long-term GH treatment will ameliorate the height deficit and almost 40% of patients may reach their target height.