Tracking and Cumulative Lifetime Exposure to IGF-I in 6459 Healthy Individuals and in SGA Children Treated With GH

Targeted proteomics of serum IGF-I, -II, IGFBP-2, -3, -4, -5, -6 and ALS

OBJECTIVES

The insulin-like growth factors (IGFs) regulate growth in humans. IGF-I and IGF binding protein (IGFBP)-3 are biomarkers in children with growth disorders. We investigate a targeted proteomics method for absolute quantitation of eight IGF protein family members in human serum, including the peptide hormones IGF-I and -II, and the six binding proteins IGFBP-2, -3, -4, -5, -6 and acid labile subunit (ALS).

METHODS

Serum preparation was optimized for targeted proteomics of IGF related proteins on a clinical LC-MS/MS platform (UHPLC coupled with Triple-Q MS). We created quality controls, standards and internal standards and 289 serum samples from healthy children and adolescents were measured in ten batches over two months. The method was compared to WHO reference standards, clinical and research immunoassays, and relative proteomics profiling.

RESULTS

The sensitivity and reproducibility were sufficient for most but not all IGF protein family members. Targeted proteomics correlated well with clinical immunoassays for IGF-I (R2=0.88) and for IGFBP-3 (R2=0.46), (p<0.001). The correlation between targeted proteomics and non-clinical immunoassays for IGF-II, IGFBP-2, -4, -5, -6 and ALS varied between proteins.

CONCLUSIONS

We present a method for parallel quantification of IGF-I, IGFBP-3, 5 and ALS for clinical verification studies, whereas targeted proteomics of the five remaining IGF related proteins (IGF-II, IGFBP-2, -4, and -6) require further examination. The sensitivity of our new IGF-I method suggests a possible diagnostic role for targeted proteomics of IGF-I in the management of children with extremely low levels of circulating IGF-I.

Somapacitan in Children Born SGA: 52-Week Efficacy, Safety, and IGF-I Response Results From the Phase 2 REAL5 Study

CONTEXT

Somapacitan, a once-weekly reversible albumin-binding growth hormone (GH) derivative, is evaluated in short children born small for gestational age (SGA).

OBJECTIVE

Evaluate efficacy, safety, tolerability as well as total and bioactive insulin-like growth factor I (IGF-I) response of once-weekly somapacitan compared to daily GH in children born SGA.

METHODS

REAL5 is a randomized, multicenter, open-label, controlled phase 2 study comprising a 26-week main phase, a 26-week extension, and an ongoing 4-year safety extension (NCT03878446), conducted at 38 sites across 12 countries. A total of 62 GH-treatment-naïve, prepubertal short children born SGA were randomized; 61 completed 52-weeks of treatment. Patients were randomized (1:1:1:1:1) to somapacitan (0.16, 0.20, or 0.24 mg/kg/week) or daily GH (0.035 or 0.067 mg/kg/day), all administered subcutaneously.

RESULTS

Estimated mean height velocity (HV; cm/year) at week 52 was 8.5, 10.4, and 10.7 cm/year for somapacitan 0.16, 0.20, and 0.24 mg/kg/week, respectively, and 9.3 and 11.2 cm/year for daily GH 0.035 and 0.067 mg/kg/day, respectively. Dose-dependent increases in total IGF-I, as well as peak IGF-I bioactivity, were observed for both treatments and were similar between comparator groups. For somapacitan, exposure-response modeling indicated highest efficacy with 0.24 mg/kg/week after 52 weeks of treatment. Similar safety and tolerability were demonstrated across all groups.

CONCLUSION

A sustained dose-dependent growth response was demonstrated for somapacitan after 52 weeks of treatment. Overall, somapacitan 0.24 mg/kg/week provides similar efficacy, safety, and tolerability, as well as comparable bioactive and total IGF-I response, as daily GH (0.067 mg/kg/day) in children born SGA.

Growth and Adult Height Attainment in Danish Transgender Adolescents Treated With GnRH Analog and Sex Hormones

BACKGROUND

Endogenous sex steroids influence the pubertal growth spurt and adult height. However, the impact of puberty suppression and sex steroids on growth in transgender adolescents is sparsely studied.

AIM

We investigated pubertal growth, serum IGF-I and IGF binding protein-3 (IGFBP-3), and adult height of transgender adolescents receiving hormone therapy.

METHODS

Observational study of a national cohort (2016-2023) comprising 219 transgender adolescents <18 years of age. Treatment consisted of gonadotropin-releasing hormone agonist combined with estradiol or testosterone (adjusted to serum concentrations between 0 and +2 SDs corresponding to the gender identity).

RESULTS

Adult height was within ±2 SD for sex assigned at birth.Most trans girls reached adult height within references of girls. For trans girls (bone age ≤15 years before treatment), a growth spurt was observed during estradiol therapy. IGF-I and height SD score (SDS) declined during oral estradiol administration (-0.13 SDS per month, P = .059, and -0.02 SDS, P = .001, respectively). We observed significantly lower adult height compared to target height for trans girls (-2.7 cm, P = .01) and significant differences between height SDS before treatment and at adult height (-0.35 SDS, P < .001).Half of the trans boys remained short (<-2 SD) compared to references for boys, and most completed growth spurt before initiation of treatment. IGFBP-3 declined following testosterone treatment. There was a significant difference between height SDS before treatment and at adult height (-0.17 SDS, P < .001).

DISCUSSION AND CONCLUSION

The minor reduction in adult height of trans girls after hormone treatment may be beneficial to some, whereas trans boys did not experience height gain.

Upregulation of Insulin-like Growth Factor-I in Response to Chemotherapy in Children with Acute Lymphoblastic Leukemia

The treatment of childhood cancer is challenged by toxic side effects mainly due to chemotherapy-induced organ damage and infections, which are accompanied by severe systemic inflammation. Insulin-like growth factor I (IGF-I) is a key regulating factor in tissue repair. This study investigated associations between the circulating IGF-I levels and chemotherapy-related toxicity in pediatric acute lymphoblastic leukemia (ALL). In this prospective study, we included 114 patients (age: 1-17 years) with newly diagnosed ALL treated according to The Nordic Society of Paediatric Haematology and Oncology (NOPHO) ALL2008 protocol between 2013 and 2018. The patients' plasma levels of IGF-I, and the primary binding protein, IGFBP-3, were measured weekly during the first six weeks of treatment, including the induction therapy. The patients' systemic inflammation was monitored by their C-reactive protein (CRP) and interleukin (IL)-6 levels and their intestinal epithelial damage by their plasma citrulline levels. IGF-I and IGFBP-3 were converted into sex-and age-adjusted standard deviation scores (SDS) using 1621 healthy children as reference. At ALL diagnosis, IGF-I levels were decreased (median (quartiles): -1.2 SDS (-1.9 to -0.5), p = 0.001), but increased significantly following the initiation of chemotherapy, peaking on day 8 (0.0 SDS (from -0.8 to 0.7), p < 0.001). This increase correlated with the levels of CRP (rho = 0.37, p < 0.001) and IL-6 (rho = 0.39, p = 0.03) on day 15, when these markers reached maximum levels. A larger IGF-I increase from day 1 to 15 correlated with a slower recovery rate of the intestinal damage marker citrulline from day 15 to 29 (rho = -0.28, p = 0.01). Likewise, IGFBP-3 was reduced at diagnosis, followed by an increase after treatment initiation, and was highly correlated with same-day IGF-I levels. This study demonstrates a chemotherapy-induced increase in IGF-I, with a response that appears to reflect the severity of tissue damage and systemic inflammation, preceding CRP and IL-6 increases. IGF-I may have potential as an early reactive biomarker for acute toxicity in patients with ALL.

Long-acting growth hormone in the management of GHD in France

Approximately 10,000 children in France with growth hormone deficiency (GHD) are being administered daily recombinant human growth hormone (rhGH). Although this treatment has long proved efficient for restoring children's growth and metabolism, daily injections of rhGH have a few limitations, such as difficulties in terms of adherence to treatment, which may compromise growth during childhood but also metabolism in adulthood. In addition to the disease burden and besides the adherence hurdles, the obligations related to daily injection have a negative impact on the quality of life of patients and their families. The hypothesis that injections administered at intervals of 1 week, or even 1 month, could improve compliance, reduce treatment discontinuations, and optimize quality of life and therapeutic effectiveness has led to the emergence of new long-acting growth hormone (LAGH). Recent access to LAGHs (somatrogon MA) on the European and French market will likely be followed by a high demand from the families concerned and may raise questions on their effectiveness, safety, and practical use. Numerous practical and practice-related points are needed to guide prescribing physicians while many concerns are still left unresolved (treatment effectiveness or ineffectiveness endpoints, long-term effectiveness, etc.). These issues can only be addressed in the future by compiling registries and conducting long-term real-world studies.

Approach to the Patient: Case Studies in Pediatric Growth Hormone Deficiency and Their Management

CONTEXT

Pathologies attributed to perturbations of the GH/IGF-I axis are among the most common referrals received by pediatric endocrinologists.

AIM

In this article, distinctive cased-based presentations are used to provide a practical and pragmatic approach to the management of pediatric growth hormone deficiency (GHD).

CASES

We present 4 case vignettes based on actual patients that illustrate (1) congenital GHD, (2) childhood GHD presenting as failure to thrive, (3) childhood GHD presenting in adolescence as growth deceleration, and (4) childhood-onset GHD manifesting as metabolic complications in adolescence. We review patient presentation and a management approach that aims to highlight diagnostic considerations for treatment based on current clinical guidelines, with mention of new therapeutic and diagnostic modalities being used in the field.

CONCLUSION

Pediatric GHD is diverse in etiology and clinical presentation. Timely management has the potential not only to improve growth but can also ameliorate or even mitigate adverse metabolic outcomes, which can be directly attributed to a GH deficient state.