Are aromatase inhibitors in boys with predicted short stature and/or rapidly advancing bone age effective and safe?

Aromatase inhibitors: a useful additional therapeutic option for slowing down advanced bone age in boys with growth hormone deficiency

INTRODUCTION

Aromatase inhibitors (AIs) have been used to slow down estrogen-dependent skeletal maturation in pubertal boys with short stature. In the literature, few data evaluate the effectiveness and safety of AIs in boys with growth hormone deficiency (GHD). This study aimed to evaluate the auxologic effects and short-term laboratory profiles of combined AI and rhGH therapy for 1 year in adolescent males with GHD.

SUBJECTS AND METHODS

Male subjects between the ages of 10 and 16 with GHD from two different centers were included in the study. Patients were divided into two groups: (i) those who only used recombinant human growth hormone (rhGH) therapy (Group I; G-I) and (ii) those who also used AI therapy (anastrozole or letrozole) along with rhGH (Group II; G-II).

RESULTS

Forty-one patients (G-I, 46%; G-II, 54%) were included in the study. All the subjects had isolated GHD. At the beginning of the treatment, the chronological ages (CAs) of the patients in the G-I and G-II groups were 11.8 (10.9-13.7) and 12.8 (12.0-14.3) years, respectively. The ratios of bone age (BA)/CA for the two groups were 0.8 (0.8-0.9) and 1.0 (0.9-1.1), respectively (p < 0.001). After the treatment, the height standard deviation (SD) scores and predicted adult height (PAH) significantly increased from baseline in all subjects in the G-I and G-II groups (p < 0.001; p < 0.001, respectively). There was no significant change in the ratio of BA/CA post-therapy in the G-I group (p = 0.1), while there was a significant decrease in the G-II group (p < 0.001). The growth velocities of the patients in the G-I and G-II groups were 9.1 (7.4-10.1) cm/year [1.5 (0.8-5.0) SD score] and 8.7 (7.5-9.9) cm/year [1.1 (0.3-3.1) SD score], respectively (p = 0.6). While post-therapy serum testosterone concentrations were seen to increase in the G-II group, none of the patients exhibited hematocrit above 50 percent, and the fasting glucose concentrations were normal.

CONCLUSIONS

When used in addition to rhGH therapy in boys with GHD and advanced BA, AIs were observed to slow down the tempo of BA maturation after 1 year, compared to those who received rhGH treatment alone. AI therapy was found to be safe during the 1-year observation period and thus could be considered for preserving growth potential in these patients.

Letrozole combined with rhGH treatment increases the adult height of short pubertal boys

OBJECTIVES

This study was performed to investigate the effectiveness of the combination of letrozole and recombinant human growth hormone (rhGH) to improve the predicted adult height (PAH) and final adult height (FAH) of Chinese short pubertal boys.

METHODS

In total, 171 Chinese short pubertal boys were recruited for this study. 96 of them received letrozole (2.5 mg/d) combined with rhGH (33.3-66.6 μg/kg.d), and the others received rhGH alone. Follow-up visits were conducted at 1, 3, 6, 9, and 12 months or regularly after the first treatment. During each visit, plasma samples were collected for clinical tests and biomedical analyses, all of which were performed according to standard protocols. This study was registered at www.chictr.org.cn under ID number ChiCTR1900026142.

RESULTS

After receiving treatment for at least 3 months, 68 boys (91 %) in the rhGH therapy group and 90 (94 %) in the letrozole combined with rhGH (letrozole+rhGH) therapy group achieved an increase in PAH, with the latter treatment leading to a more effective slowing of bone age (BA) advancement. Moreover, the increased PAH showed a significant positive correlation with treatment time in both groups, and letrozole+rhGH increased the PAH to a greater degree than rhGH alone (p=0.0023). And letrozole+rhGH not only slowed the increase in BA more efficiently than rhGH therapy alone (p=0.0025), but also achieved a higher FAH (p=0.0078).

CONCLUSIONS

Letrozole combined with rhGH treatment is a promising therapy to increase the PAH and FAH of Chinese short pubertal boys.

The effect of anastrozole therapy on final height and sex hormone levels in pubertal boys receiving growth hormone therapy

Objective

This research aimed to evaluate retrospectively the effect of anastrozole on height gain and sex hormone levels in pubertal boys receiving growth hormone (GH).

Materials and methods

Pubertal boys who received both GH and anastrozole (GH+A) were one-to-one matched with boys who received only GH (GH-Only) for chronological and bone age, pubertal stage and height before the GH initiation, treatment duration and midparental height. Anthropometric measurements throughout treatment and adult heights were compared between the groups. Sex hormone levels were evaluated longitudinally in the GH+A group.

Results

Forty-eight cases (24 in each group) were included. There was no statistical difference in adult height between the GH+A and GH-Only (p = 0.071). However, when the analysis was limited to those receiving anastrozole for at least 2 years, mean adult height was higher in the GH+A than in the GH-Only group (173.1 ± 6.2/169.8 ± 5.6 cm, p = 0.044). Despite similar growth rates between the two groups, bone age advancement was slower in the GH+A than in the GH-Only in a mean anastrozole treatment period of 1.59 years (1.37 ± 0.80/1.81 ± 0.98 years, p = 0.001). The greatest increase for FSH, LH, total and free testosterone and decrease for estradiol levels were observed in the third month after anastrozole was started, albeit remaining within the normal ranges according to the actual pubertal stages.

Conclusion

Using anastrozole with GH for at least 2 years decelerates the bone age advancement resulting in adult height gain with no abnormality in sex hormone levels. These results suggest anastrozole can be used as an additional treatment to GH for further height gain in pubertal boys.

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.

Treatment of Short Stature with Aromatase Inhibitors: A Systematic Review and Meta-Analysis

The objective of the study is to determine the risks and benefits of treating idiopathic short stature (ISS) with aromatase inhibitors (AIs). We comprehensively searched PubMed, Embase, and the China National Knowledge Infrastructure between establishment year and January 31, 2020. Mean difference (MD)/Standardized mean differences (SMD) with 95% confidence intervals (CI) of individual studies were pooled using fixed or random effects models. Subgroup and sensitivity analyses were also performed. Publication bias was estimated using funnel plots and Egger tests. Fourteen studies including 388 participants were included. The meta-analysis results showed that AIs significantly increased final height (MD=2.46, 95% CI: 0.8-4.12) and predicted adult height (MD=0.34, 95% CI: 0.11-0.57). Changes in bone age (MD=-0.1, 95% CI: -0.86-0.66) and bone mineral density (MD=-0.05, 95% CI: -0.19-0.1) were not different between intervention and control group. AI significantly increased testosterone level (SMD=2.01, 95% CI: 0.8-3.23) and reduced estradiol level (SMD=-1.13, 95% CI: -1.87 to -0.40); The intervention and control group had no significant differences in the levels of high-density lipoprotein-cholesterol (SMD=-0.31, 95%CI: -0.68-0.06) and IGF-1 (SMD=0.7, 95% CI: -0.66-2.06) levels. Adverse events were more frequent in the intervention group than in the control group (odds ratio=3.12, 95% CI: 1.44-6.73). In conclusion, both AI monotherapy and AI combination therapy can increase predicted adult height and testosterone levels.

Should Skeletal Maturation Be Manipulated for Extra Height Gain?

Skeletal maturation can be delayed by reducing the exposure to estrogens, either by halting pubertal development through administering a GnRH analogue (GnRHa), or by blocking the conversion of androgens to estrogens through an aromatase inhibitor (AI). These agents have been investigated in children with growth disorders (off-label), either alone or in combination with recombinant human growth hormone (rhGH). GnRHa is effective in attaining a normal adult height (AH) in the treatment of children with central precocious puberty, but its effect in short children with normal timing of puberty is equivocal. If rhGH-treated children with growth hormone deficiency or those who were born small-for-gestational age are still short at pubertal onset, co-treatment with a GnRHa for 2-3 years increases AH. A similar effect was seen by adding rhGH to GnRHa treatment of children with central precocious puberty with a poor AH prediction and by adding rhGH plus GnRHa to children with congenital adrenal hyperplasia with a poor predicted adult height on conventional treatment with gluco- and mineralocorticoids. In girls with idiopathic short stature and relatively early puberty, rhGH plus GnRHa increases AH. Administration of letrozole to boys with constitutional delay of growth puberty may increase AH, and rhGH plus anastrozole may increase AH in boys with growth hormone deficiency or idiopathic short stature, but the lack of data on attained AH and potential selective loss-of-follow-up in several studies precludes firm conclusions. GnRHas appear to have a good overall safety profile, while for aromatase inhibitors conflicting data have been reported.

Disorders of Puberty: Pharmacotherapeutic Strategies for Management

During puberty, with activation of the hypothalamic pituitary axis that has been quiescent since the neonatal period, linear growth accelerates, secondary sexual characteristics develop, and adult fertility potential and bone mass are achieved, together with psychosocial and emotional maturation.Disordered pubertal onset and progress, either early or late, presents frequently for endocrine care. Where a disorder is found, due either to a central hypothalamic pituitary cause or to primary gonadal failure, pharmacotherapeutic interventions are required to alter the trajectory of disturbed pubertal onset or progress and for maintenance of adolescent and adult sex hormone status. This paper describes pharmacologic interventions used for pubertal disorders but is not intended to address the diagnostic cascade in detail.

Potential Value of Conventional Ultrasound in Estimation of Bone Age in Patients from Birth to Near Adulthood

We aimed to assess the relationship between standard bone age (BA) stratification obtained using plain radiography and that obtained using ultrasound determination of ossification ratio (OR) as a novelty in patients from birth to near adulthood. The ratio of diameters of the ossification center and epiphysis was calculated to evaluate the OR of bones. The ORs of the bones assigned to different weight coefficient were then summed as the skeletal maturity score (SMS). Pearson's correlation r between SMSs derived from ORs and BAs was 0.97 in girls (p < 0.001) and 0.97 in boys (p < 0.001), respectively. There are significant positive correlations between SMSs measured by conventional ultrasound imaging and BAs obtained by radiography of the hand and wrist in patients from birth to near adulthood. The scoring system may potentially provide a quantitative modality to estimate BA by conventional ultrasound.

Human cytochrome P450 enzymes 5-51 as targets of drugs and natural and environmental compounds: mechanisms, induction, and inhibition - toxic effects and benefits

Cytochrome P450 (P450, CYP) enzymes have long been of interest due to their roles in the metabolism of drugs, pesticides, pro-carcinogens, and other xenobiotic chemicals. They have also been of interest due to their very critical roles in the biosynthesis and metabolism of steroids, vitamins, and certain eicosanoids. This review covers the 22 (of the total of 57) human P450s in Families 5-51 and their substrate selectivity. Furthermore, included is information and references regarding inducibility, inhibition, and (in some cases) stimulation by chemicals. We update and discuss important aspects of each of these 22 P450s and questions that remain open.