An open label 12-month pilot trial on the effects of the aromatase inhibitor anastrozole in growth hormone (GH)-treated GH deficient adolescent boys

Anastrozole monotherapy further improves near-adult height after the initial combined treatment with leuprorelin and anastrozole in early-maturing girls with compromised growth prediction: results from the second phase of the GAIL study

Background

The first phase of the GAIL study ("Girls treated with an Aromatase Inhibitor and Leuprorelin," ISRCTN11469487) has shown that the combination of anastrozole and leuprorelin for 24 months is safe and effective in improving the predicted adult height (PAH) in girls with early puberty and compromised growth prediction by +1.21 standard deviation score (SDS; +7.51 cm) compared to inhibition of puberty alone, +0.31 SDS (+1.92 cm).

Objectives and hypotheses

In the second phase of the GAIL study, we assessed the adult height (AH)/near-adult height (NAH) at the end of the first phase and, in addition, the efficacy of anastrozole monotherapy thereafter in further improving NAH.

Methods

We measured the AH (age 16.5 years)/NAH [bone age (BA), 15 years] of the 40 girls included, divided into two matched groups: group A (20 girls on anastrozole + leuprorelin) and group B (20 girls on leuprorelin alone). Group A was further randomized into two subgroups: A1 and A2. Group A1 (n = 10), after completion of the combined therapy, received anastrozole 1 mg/day as monotherapy until BA 14 years, with a 6-month follow-up. Group A2 (n = 10) and group B (n = 20), who received only the combined treatment and leuprorelin alone, respectively, were recalled for evaluation of AH/NAH.

Results

AH or NAH exceeded the PAH at the completion of the 2-year initial phase of the GAIL study in all groups, but the results were statistically significant only in group A1: NAH-PAH group A1, +3.85 cm (+0.62 SDS, p = 0.01); group A2, +1.6 cm (+0.26 SDS, p = 0.26); and group B, +1.7 cm (+0.3 SDS, p = 0.08). The gain in group A1 was significantly greater than that in group A2 (p = 0.04) and in group B (p = 0.03). Anastrozole was determined to be safe even as monotherapy in Group A1.

Conclusions

In early-maturing girls with compromised growth potential, the combined treatment with leuprorelin and anastrozole for 2 years or until the age of 11 years resulted in a total gain in height of +9.7 cm when continuing anastrozole monotherapy until the attainment of NAH, as opposed to +7.4 cm if they do not continue with the anastrozole monotherapy and +3.6 cm when treated with leuprorelin alone. Thus, the combined intervention ends at the shortest distance from the target height if continued with anastrozole monotherapy until BA 14 years.

Use of letrozole to augment height outcome in pubertal boys: a retrospective chart review

OBJECTIVES

We describe growth patterns and predicted adult height (PAH) in pubertal boys treated with letrozole and evaluate the potential predictors of growth responses.

METHODS

We performed a retrospective analysis of data from 2002 to 2020. All subjects were treated for ≥6 months and had at least 3 height measurements to calculate the growth velocity (GV) before and during treatment. We evaluated growth measurements, bone age, and biochemical parameters before, during and after treatment.

RESULTS

A total of 59 subjects aged 12.7 (± 1.7) years old were included. At treatment initiation, bone age was 13.1 (± 1.5) years and predicted adult height (PAH) was 163.8 (± 9.9) cm compared to mid-parental height of 172.4 (± 5.8) cm. Growth velocity decreased during letrozole therapy and rebounded after completion. Sub-analysis of 26 subjects with bone age data available at baseline and at least 1 year later showed a trend to modest increase in PAH. In boys simultaneously receiving growth hormone (rhGH), the change in PAH was significantly more (3.2 cm, p<0.05) compared to those treated with letrozole alone.

CONCLUSIONS

We show that letrozole appropriately slows down skeletal maturation and GV responses are variable. Possible negative predictors include lower baseline GV and advanced bone age. A small positive trend in PAH with letrozole therapy is augmented by simultaneous use of rhGH. Future randomized controlled trials are needed to better understand which group of patients will benefit from treatment.

The Effect of Anastrozole on the Lipid Profile: Systematic Review and Meta-analysis of Randomized Controlled Trials

PURPOSE

We aimed to investigate the impact of anastrozole administration on the traditional components of the lipid profile (ie, total cholesterol [TC], LDL-C, HDL-C, and triglycerides [TGs]) by means of a systematic review and meta-analysis of randomized controlled trials.

METHODS

We searched the PubMed/Medline, Scopus, Embase, and Web of Science databases for relevant randomized controlled trials published in the English language until January 18, 2022. The weighted mean difference (WMD) and 95% CIs were calculated using a random-effects model (DerSimonian and Laird methods).

FINDINGS

Anastrozole administration significantly lowered TC concentrations when the treatment duration was ≤3 months (WMD = -2.73 mg/dL; 95% CI, -5.09 to -0.38 mg/dL; P = 0.02) and when the baseline TC concentration was ≥200 mg/dL (WMD = -3.64 mg/dL; 95% CI, -6.30 to -0.98 mg/dL; P = 0.007). HDL-C levels decreased after anastrozole administration when the treatment duration was >3 months (WMD = -1.67 mg/dL; 95% CI, -3.24 to -0.10 mg/dL; P = 0.03). Anastrozole administration had no impact on TG or LDL-C values.

IMPLICATIONS

Anastrozole administration in humans can decrease TC and HDL-C levels but has no effect on LDL-C or TG concentrations.

Estrogenic activity of biological samples as a biomarker

Biological assays can evaluate the cumulative effect of a mixture, considering synergistic/antagonistic interactions and effects of unknown/unconsidered compounds. Therefore, their application could increase in the next years also to analyse biological samples. The aim of this review is to discuss the methodological approach and the application of estrogenic activity assays in human biological samples. 75 research articles were analysed and divided according to whether they used these assays: i) to quantify the level of estrogens and/or as a biomarker of estrogenic status ii) as a biomarker of exposure to endocrine disrupting chemicals (EDCs). For the first purpose, some authors extracted biological samples while others tested them directly without any treatment. The study of these methodologies outlined that the methodology applied influenced the specificity of analysis. The estrogenic activity biomarker was used to analyse physiological variations of estrogens, pediatric diseases, hormone-dependent diseases and estrogen suppression/enhancement after pharmaceutical treatments. For the second purpose, some authors extracted samples while others tested them directly, some authors divided endogenous estrogens from xenoestrogens while others tested samples without separation. The analysis of these methodologies outlined some limitations related to the efficiency of extraction and the incorrect separation of some compounds. The studies which applied this EDC biomarker showed that it was correlated with some EDCs, it varied according to the exposure of the population and it allowed the identification of some relationships between EDC exposure and breast cancer, type 1 diabetes and adverse health effects on children. In conclusion, the estrogenic activity of biological samples can be a useful tool: to quantify low levels of 17β-estradiol, to assess the combined effect of endogenous estrogens and xenoestrogens, to estimate the estrogenic status providing considerable insight into physiological or pathological conditions, to evaluate EDC presence implementing the existing knowledge about EDC exposure and adverse health effects.

Restoration of Height after 11 Years of Letrozole Treatment in 11β-Hydroxylase Deficiency

11β-hydroxylase deficiency (11β-OHD) is the second most common form of congenital adrenal hyperplasia (CAH). Males with 11β-OHD CAH are often diagnosed late with a significantly advanced bone age leading to a poor height prognosis due to early closure of epiphysis. Delaying epiphyseal fusion by treatment of aromatase inhibitors (AIs) might be a useful strategy in patients with very advanced bone ages. However, there are limited data regarding the effect on final height and long-term safety of this approach. We report our experience with 11 years of letrozole treatment and 17 years of follow-up in a boy with 11β-OHD. He presented at 2 years and 11 months of age with a bone age of 13 years (predicted adult height, PAH, 129.5 cm). Letrozole was added after 1 year of glucocorticoid treatment due to no improvement in height prognosis (130 cm), and continued until the age of 14 years and 11 months. He also received GnRH analog treatment at 10 years and 3 months of age for 2.5 years due to central activation of puberty. He reached a final height of 165.2 cm (35.2 cm above his PAH). This long-term treatment with letrozole was associated with changes in vertebral morphology such as vertebral body end-plate changes, Schmorl nodes, and mild protrusions in the intervertebral discs. Testicular volumes, gonadotropins, testosterone, and anti-Müllerian hormone were normal at age 20 years. A spermiogram showed a normal count but impaired sperm motility and morphology. This unique case represents the longest duration of AI treatment reported in CAH and the first case in which letrozole was started before puberty with the final height reported. We conclude that AIs may restore height in selected patients with CAH with very advanced bone age and severely compromised height prognosis.

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.

Anastrozole plus leuprorelin in early maturing girls with compromised growth: the "GAIL" study

PURPOSE

Aromatase inhibitors have been used to increase predicted adult height (PAH) in boys but in girls only in McCune-Albright syndrome. We investigated whether anastrozole combined with leuprorelin for up to 2 years is safe and effective in improving PAH in girls with early puberty and compromised growth, compared to leuprorelin alone.

METHODS

The "GAIL" study: girls treated with an aromatase inhibitor and an LHRH analogue, ISRCTN11469487, was a 7-year prospective phase IIa study with parallel design, performed at Athens Medical Center (C-A), and Attikon University Hospital, Athens, Greece (C-B). Forty girls, consecutively referred for early puberty (onset 7.5-9 years) with a PAH <-2 or >1.5 SD lower than their target height (TH), were included. Twenty started on leuprorelin sc/im 0.3 mg/kg/month plus anastrozole 1 mg/d p.o. (group-A, C-A) and 20 on leuprorelin (group-B, C-B) for 2 years or until the age of 10 years. Groups did not differ in age, height, BMI, bone age advancement (BAA), and distance of PAH from TH. Follow-up was at 6, 12, 18, and 24 m.

RESULTS

Reduction in BAA was significantly higher in group-A compared to group-B already by 6 m. Despite the transiently significant decrease in height velocity in group-A, gain in PAH SD was almost double by 12 and 18 m vs group-B and reached the maximum of +1.21 ± 0.45 (7.51 cm) vs +0.31 ± 0.37 (1.92 cm, p = 0.001) in group-B at 24 m. Group-A had no clinical or biochemical hyperandrogenism, unchanged normal bone density, and lumbar spine X-rays.

CONCLUSION

The co-administration of anastrozole with leuprorelin safely improves PAH in girls with compromised growth.

Aromatase inhibitors for short stature in male children and adolescents

BACKGROUND

As a result of the essential role of oestrogens in epiphyseal closure, aromatase inhibitors have been trialled as an intervention to improve height outcomes in male children and adolescents by inhibiting the conversion of testosterone to oestradiol.

OBJECTIVES

To assess the effects of aromatase inhibitors in male children and adolescents with short stature.

SEARCH METHODS

To identify relevant trials, we searched the Cochrane Library (2014, Issue 7), MEDLINE, EMBASE, and the World Health Organization (WHO) ICTRP trial register from their inception until August 2014. In addition, we conducted citation searches and screened reference lists of included trials.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) if they compared use of an aromatase inhibitor with placebo in male children and adolescents with short stature.

DATA COLLECTION AND ANALYSIS

Two authors independently screened titles and abstracts for relevance. Both authors carried out screening for inclusion, data extraction, and risk of bias assessment, with any disagreements resolved following discussion. We assessed trials for quality of evidence using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) instrument. We contacted study authors regarding missing information. Primary outcomes were final or near-final height, adverse events, and health-related quality of life. Secondary outcomes included all-cause mortality, cognitive outcomes, socioeconomic effects, laboratory measures, short-term growth parameters, and assessment of effects on bone health. Meta-analysis was not appropriate due to the substantial clinical heterogeneity between trials; we presented the findings of the review in narrative format.

MAIN RESULTS

We included four RCTs involving 207 participants (84 on interventions) in the review. Trials included males with constitutional delay of growth and puberty (CDGP), idiopathic short stature (ISS), and growth hormone (GH) deficiency. Three of the trials had an overall low or unclear risk of bias for primary outcomes. Short-term growth outcomes, such as predicted adult height, improved in all trials. Just one trial reported the primary outcome of final and near-final height as an extension under non-randomised conditions. None of the trials assessed health-related quality of life. One publication provided detailed information regarding the incidence of adverse events. A significant proportion (45%) of prepubertal boys with ISS treated with letrozole developed mild morphological abnormalities of their vertebrae, compared with none in the placebo group.

AUTHORS' CONCLUSIONS

Available evidence suggested that aromatase inhibitors improved short-term growth outcomes. There was no evidence to support an increase in final adult height, based on limited data, with only one of four trials publishing final height data under non-randomised conditions.

Is there a role for estrogen activity assays? Recombinant cell bioassay for estrogen: Development and applications

There are many questions which cannot be answered without a very sensitive estradiol assay. A recombinant cell bioassay (RCBA) for estradiol was developed in 1994. The sensitivity of the bioassay is 0.02-0.2 pg/ml (0.07-0.7 pmol/L), more than 20 times more sensitive than commercial RIAs and 10 times more sensitive than newer mass spectrometry assays. The RCBA for estradiol opened the door to study low levels of estradiol equivalents (EE) across the physiological spectrum of life from prepubertal children through menopause and across the spectrum from normal physiology, in boys as well as girls, to pathology, including: premature thelarche; estradiol suppression in children treated with GnRH analogues for precocious puberty; aromatase inhibition in boys with growth hormone deficiency; the differences between oral and transdermal routes of estrogen administration in girls with Turner's syndrome; women with breast cancer treated with aromatase inhibitors; and women with urogenital atrophy treated with low dose vaginal estrogen. A bioassay also allows study of endocrine disruptors, like phytoestrogens and other environmental compounds, which are relevant to public health and alternative medicine options. This paper reviews the assay and the last 20 years of applications. A bioassay for estrogen has a role because measuring biological effect is theoretically useful, increasing the understanding of physiology in addition to biochemical levels, giving different information than other assays, and opening the door to measure very low levels of estrogen activity in both humans and the environment.

A randomized pilot trial of growth hormone with anastrozole versus growth hormone alone, starting at the very end of puberty in adolescents with idiopathic short stature

BACKGROUND

When given during the course of puberty, anastrozole (A), an aromatase inhibitor, has been shown to increase the predicted adult height (PAH) of GH-deficient (GHD) boys treated with recombinant human growth hormone (rhGH). Our study questioned whether this treatment could retain some of its effects in non-GHD adolescent boys if started only at the very end of puberty, a time when rhGH treatment is denied to short adolescents who have almost reached their final height.

OBJECTIVE

To explore the effect on adult height of a combination of rhGH and A, compared with rhGH alone, at the end of puberty in boys with idiopatic short stature (ISS).

METHODS

A prospective randomized study comparing rhGH + A and rhGH was conducted in 24 healthy adolescent boys aged 15.2 ± 1.2 yrs with serum testosterone at adult levels and a faltering growth velocity <3.5 cm/yr leading to a predicted adult height (PAH) <2.5 SDS. Treatments were stopped when growth velocity became <10 mm in 6 months or when height was close to 170 cm. A historical group of ISS adolescents (N = 17) matched for puberty and growth was used for comparison.

RESULTS

IGF1 levels remained within normal limits in all treated patients. Mean treatment duration was 19 months in the rhGH + A group and 11.5 months in the rhGH group (P = 6.10(-4)). Adult height reached 168.4 ± 2.6 cm in the rhGH + A group and 164.2 ± 5.6 cm in the rhGH group (P < 0.02). Adult height was 160.1 ± 2.8 cm in the historical controls.

CONCLUSION

A combination of rhGH and A, started at the very end of puberty, seems to allow boys with ISS to reach a greater adult height than rhGH alone. Larger trials are needed to confirm this preliminary observation.

Aromatase inhibitors in pediatrics

Aromatase, an enzyme located in the endoplasmic reticulum of estrogen-producing cells, catalyzes the rate-limiting step in the conversion of androgens to estrogens in many tissues. The clinical features of patients with defects in CYP19A1, the gene encoding aromatase, have revealed a major role for this enzyme in epiphyseal plate closure, which has promoted interest in the use of inhibitors of aromatase to improve adult height. The availability of the selective aromatase inhibitors letrozole and anastrozole--currently approved as adjuvant therapy for breast cancer--have stimulated off-label use of aromatase inhibitors in pediatrics for the following conditions: hyperestrogenism, such as aromatase excess syndrome, Peutz-Jeghers syndrome, McCune-Albright syndrome and functional follicular ovarian cysts; hyperandrogenism, for example, testotoxicosis (also known as familial male-limited precocious puberty) and congenital adrenal hyperplasia; pubertal gynecomastia; and short stature and/or pubertal delay in boys. Current data suggest that aromatase inhibitors are probably effective in the treatment of patients with aromatase excess syndrome or testotoxicosis, partially effective in Peutz-Jeghers and McCune-Albright syndrome, but probably ineffective in gynecomastia. Insufficient data are available in patients with congenital adrenal hyperplasia or functional ovarian cysts. Although aromatase inhibitors appear effective in increasing adult height of boys with short stature and/or pubertal delay, safety concerns, including vertebral deformities, a decrease in serum HDL cholesterol levels and increase of erythrocytosis, are reasons for caution.

Strategies for maximizing growth in puberty in children with short stature

The approach to the child with growth retardation who is in puberty remains an important clinical challenge. The use of high-dose growth hormone (GH), suppression of puberty with GnRH analogs in combination with GH, and the use of selective inhibitors of the aromatase enzyme with aromatase inhibitors (also in combination with GH) are all therapeutic choices that have been studied. Aromatase blockade effectively blocks estrogen production in males with a reciprocal increase in testosterone, and a new generation of aromatase inhibitors, including anastrozole, letrozole and exemestane, is under investigation in adolescent subjects with severe growth retardation. This class of drugs, if judiciously used for a window of time, offers promise as an adjunct treatment of growth delay in pubertal patients with GH deficiency, idiopathic short stature, testotoxicosis, and other disorders of growth. These evolving uses of aromatase inhibitors, however, represent off-label use of the product, and definitive data on their efficacy are not available for each of the conditions mentioned. Safety issues regarding bone health also require further study.

Impaired reproduction in adult male, but not female, rats following juvenile treatment with the aromatase inhibitor, exemestane

BACKGROUND

Exemestane is an irreversible steroidal inhibitor of cytochrome-P450 aromatase required for estrogen synthesis. The safety of the drug in the pediatric population, particularly in males, has not previously been evaluated. Given the increased interest in treating children with aromatase inhibitors, we undertook a study in rats to assess the potential for exemestane to alter reproductive development and function when administered to juveniles.

METHODS

Male and female rats were treated with exemestane at doses anticipated to produce exposures approximately 2- and 35-fold the expected clinical plasma exposure in young adult males during the period of reproductive maturation. After maturation, treated rats were mated to evaluate the potential impact on reproductive function.

RESULTS AND CONCLUSION

There were no effects on sexual maturation in either sex or on female reproductive function. Treatment of juvenile male rats caused increased cohabitation time and decreased copulation rates; pregnancy rates and litter size were not affected in rats that mated. Decreased testis (10-15%) and epididymis (20-30%) weights, and decreased Sertoli cell numbers were noted at all doses. This indicates that exemestane can reduce Sertoli cell proliferation during maturation. The sensitive window for this effect is expected to be limited to the period of Sertoli cell proliferation, which is completed by around postnatal day 15 in rats and before puberty in humans. Treatment beginning at a later time relative to the window for Sertoli cell proliferation or for a longer duration is not expected to have additional adverse effect as the effect was not shown to be degenerative.

Bicalutamide plus anastrozole for the treatment of gonadotropin-independent precocious puberty in boys with testotoxicosis: a phase II, open-label pilot study (BATT)

OBJECTIVE

To evaluate the efficacy, tolerability, and pharmacokinetics of bicalutamide plus anastrozole in young males with testotoxicosis.

METHODS

This was a multicenter, open-label, single-arm, 12-month, Phase II pilot trial in 14 males (2-9 years) with testotoxicosis treated with bicalutamide (12.5, 25, 50, or 100 mg) and anastrozole (0.5 or 1 mg) daily. The primary outcome was change in growth rate.

RESULTS

At 1 year, the mean (standard deviation) change from baseline in growth rate was -1.6 (+/- 5.1) cm/year and -0.1 (+/- 1.8) SD units, and in bone maturation was -2.3 (+/- 0.5) years. The bone age/chronological age ratio was reduced from 2.1 (+/- 0.6) at baseline to 1.0 (+/- 0.4) (p = 0.00013). Steady-state trough R-bicalutamide and anastrozole concentrations were attained by Day 21 and 8, respectively. Gynecomastia (42.9%) and breast tenderness (12.5%) were the most common treatment-related adverse events.

CONCLUSIONS

Treatment of testotoxicosis with bicalutamide plus anastrozole resulted in slower growth rate.

Strategies for maximizing growth in puberty in children with short stature

The approach to the child with growth retardation who is in puberty remains an important clinical challenge. The use of high-dose growth hormone (GH), suppression of puberty with GnRH analogs in combination with GH, and the use of selective inhibitors of the aromatase enzyme with aromatase inhibitors (also in combination with GH) are all therapeutic choices that have been studied. Aromatase blockade effectively blocks estrogen production in males with a reciprocal increase in testosterone, and a new generation of aromatase inhibitors, including anastrozole, letrozole and exemestane, is under investigation in adolescent subjects with severe growth retardation. This class of drugs, if judiciously used for a window of time, offers promise as an adjunct treatment of growth delay in pubertal patients with GH deficiency, idiopathic short stature, testotoxicosis, and other disorders of growth. These evolving uses of aromatase inhibitors, however, represent off-label use of the product, and definitive data on their efficacy are not available for each of the conditions mentioned. Safety issues regarding bone health also require further study.

Pharmacokinetics and pharmacodynamics of anastrozole in pubertal boys with recent-onset gynecomastia

CONTEXT

Use of aromatase inhibitors to suppress estrogen production is being actively investigated in a variety of experimental conditions in both females and males. Anastrozole (Arimidex) is a potent and selective reversible inhibitor of the aromatase enzyme in females.

OBJECTIVE

Our objective was to characterize the pharmacokinetics (PK) and pharmacodynamics (PD) of anastrozole in adolescent males with gynecomastia of less than 1 yr duration. The effect of anastrozole on breast size was also assessed as an exploratory aim.

DESIGN

We conducted a PK/PD open-label study.

SETTING

This clinical research center study was undertaken at pediatric academic centers.

PATIENTS

Forty-two boys with gynecomastia (mean age 13 +/- 1.8 yr; duration of gynecomastia 7.0 +/- 2.5 months; body mass index 28.3 +/- 5.9 kg/m(2)) were recruited.

INTERVENTIONS

Anastrozole, 1 mg, was given daily for 6 months.

MAIN OUTCOMES

We assessed PK/PD of anastrozole after 14 d daily dosing and changes in breast size (exploratory aim) by manual tape measurements (area) and ultrasound (volume) after 6 months.

RESULTS

Anastrozole was rapidly absorbed orally (time to reach maximum concentration, 1 h) with a slow apparent clearance of 1.54 liters/h and a terminal half-life of 46.8 h. Testosterone/estradiol ratios increased significantly with concomitant increase in LH/FSH concentrations indicating aromatase blockade. There was a reduction in breast area (approximately 63%) and breast volume (approximately 57%) in the study group as compared with baseline (P = 0.004). The drug was well tolerated.

CONCLUSIONS

Anastrozole is a potent aromatase inhibitor in adolescent males, with rapid absorption and slow elimination kinetics after oral dosing. Exploratory analysis of changes in breast size showed breast reduction in the cohort; this deserves further study.

The aromatase inhibitor anastrozole is ineffective in the treatment of precocious puberty in girls with McCune-Albright syndrome

CONTEXT

Precocious puberty (PP) in girls with McCune-Albright syndrome (MAS) is characterized by episodic development of large unilateral ovarian cysts followed by sudden onset of vaginal bleeding. Some patients experience frequent bleeding as well as accelerated linear growth and advanced skeletal maturation. The use of anastrozole for the treatment of PP in this condition has not been well studied.

OBJECTIVE

The objective of the study was to determine the safety and efficacy of the aromatase inhibitor anastrozole for the treatment of PP in girls with MAS.

DESIGN AND SETTINGS

This was a prospective international multicenter study in which subjects received anastrozole 1 mg daily for 1 yr.

PATIENTS

Twenty-eight girls 10 years of age or younger with MAS and progressive PP were enrolled.

MAIN OUTCOME MEASURES

Vaginal bleeding, rate of skeletal maturation (change in bone age over change in chronological age), growth velocity, and uterine/ovarian volumes were measured. These indices were compared with a 6-month pretreatment interval.

RESULTS

No difference in vaginal bleeding (mean number of days per year) was noted. Mean change in DeltaBA/DeltaCA, which was 1.25 +/- 0.77 at baseline, was -0.25 +/- 1.02 at study end (P = 0.22). Average growth velocity z score was 1.40 +/- 3.15 at study entry and 0.26 +/- 2.71 at 12 months (P = 0.10). Mean ovarian/uterine volumes were unaffected by anastrozole, and no significant adverse events occurred.

CONCLUSIONS

Although it appears safe, anastrozole for 1 yr was ineffective in halting vaginal bleeding, attenuating rates of skeletal maturation, and linear growth in girls with MAS. Pharmacological strategies other than anastrozole should be pursued for the treatment of PP in this population.

Use of aromatase inhibitors in children and adolescents with disorders of growth and adolescent development

Although treatment of children and adolescents who have disorders of growth and adolescent development with aromatase inhibitors is increasingly common, data for or against their use are extremely limited. Precocious puberty, short stature, and gynecomastia are conditions for which inhibition of the enzyme aromatase might prove beneficial to reduce clinical signs of estrogenization and/or estrogen-mediated skeletal maturation. In this report, we summarize the published data regarding the use of aromatase inhibitors in these conditions, and review known and potential benefits, safety concerns, and shortcomings of the available information.

Idiopathic short stature: management and growth hormone treatment

In the management of ISS auxological, biochemical, psychosocial and ethical elements have to be considered. In boys with constitutional delay of growth and puberty androgens are effective in increasing height and sexual characteristics, but adult height is unchanged. GH therapy is efficacious in increasing height velocity and adult height, but the inter-individual variation is considerable. The effect on psychosocial status is uncertain. Factors affecting final height gain include GH dose, height deficit in comparison to midparental height, age and first year height velocity. In case of a low predicted adult height at the onset of puberty, addition of a GnRH analogue can be considered. Although GH therapy appears safe, long-term monitoring is recommended.

Anastrozole increases predicted adult height of short adolescent males treated with growth hormone: a randomized, placebo-controlled, multicenter trial for one to three years

CONTEXT

The process of epiphyseal fusion during puberty is regulated by estrogen, even in males.

OBJECTIVE

Our objective was to investigate whether anastrozole, a potent aromatase inhibitor, could delay bone age acceleration and increase predicted adult height in adolescent boys with GH deficiency.

METHODS

Fifty-two adolescent males with GH deficiency treated with GH were randomized to cotreatment with anastrozole or placebo daily for up to 36 months.

RESULTS

Fifty subjects completed 12 months, 41 completed 24 months, and 28 completed 36 months. Linear growth was comparable between groups; however, there was a significantly slower increase in bone age advancement from baseline in the anastrozole group vs. placebo group after 2 yr (+1.8+/-0.1 vs. +2.7+/-0.1 yr, P<0.0001) and after 3 yr (+2.5+/-0.2 vs. +4.1+/-0.1 yr, P<0.0001). This resulted in a net increase in predicted adult height of +4.5+/-1.2 cm in the anastrozole group at 24 months and +6.7+/-1.4 cm at 36 months as compared with a 1-cm gain at both time points in the placebo group. Estradiol and estrone concentrations increased less in the anastrozole group compared with placebo group. All boys on the aromatase inhibitor had normal tempo of virilization. Safety data, including glucose, and plasma lipid concentrations were comparable between groups.

CONCLUSIONS

Anastrozole increases adult height potential of adolescent boys on GH therapy while maintaining normal pubertal progression after 2-3 yr. This treatment offers an alternative in promoting growth in GH-deficient boys in puberty. Long-term follow up is needed to elucidate fully the safety and efficacy of this approach.

Of mice and men: the many guises of estrogens

Models of estrogen insufficiency have revealed new and unexpected roles for estrogens in males as well as females. These models include natural mutations in the aromatase gene in humans, as well as mouse knock-outs of aromatase and the estrogen receptors, and one man with a mutation in the ERa gene. These mutations, both natural and experimental, have revealed that estrogen deficiency results in a spectrum of symptoms. These include loss of fertility and libido in both males and females; loss of bone in both males and females; a cardiovascular and cerebrovascular phenotype; development of a metabolic syndrome in both males and females, with truncal adiposity and male-specific hepatic steatosis. Most of these symptoms can be reversed or attenuated by estradiol therapy. Thus estrogen is involved in the maintenance of general physiological homeostasis in both sexes.

Gonadal steroids and bone metabolism in men

PURPOSE OF REVIEW

Over the past decade, our increasing awareness of the clinical importance of osteoporosis in men has stimulated intense interest in trying to better understand male skeletal physiology and pathophysiology. The present review focuses on a major focus of research in this area, namely the attempt to define the influence and therapeutic potential of gonadal steroids in male bone metabolism.

RECENT FINDINGS

Building on previous work defining the relative roles of androgens and estrogens in the developing male skeleton and in maintaining normal bone turnover, recent studies have begun to define these issues from epidemiologic, physiologic and therapeutic perspectives. With access to data from large prospectively defined populations of men, investigators are confirming and challenging existing hypotheses and forwarding new concepts. Clinical trials have expanded beyond standard androgen replacement studies to explore more complex hormonal interventions. Physiologic investigation has continued to probe the mechanisms underlying the differential and independent roles of androgens and estrogens in male bone metabolism.

SUMMARY

Recent work has added significantly to our understanding of the role of gonadal steroids in male skeletal physiology. Nonetheless, further research is necessary to build on these initial human studies and to capitalize on rapidly emerging advances in our understanding of the basic biology of bone metabolism.

Treatment of familial male-limited precocious puberty with bicalutamide and anastrozole

This report describes the use of bicalutamide and anastrozole in two subjects with familial male-limited precocious puberty. Clinical improvements include decreased facial acne and pubic hair. Most importantly, a marked decrease in growth velocity and skeletal advancement has been achieved.

Estradiol levels and secretory dynamics in normal girls and boys as determined by an ultrasensitive bioassay: a 10 year experience

We utilized an ultrasensitive recombinant cell bioassay to measure serum estradiol in 800 normal children from birth through puberty. 105 children had repeat samples every 4 months as they approached puberty. We measured estradiol levels every hour for 24 hours in 55 children. Estradiol increased with age and pubertal stage in girls and boys, and was higher in girls than boys at each stage. Prepubertal girls have estradiol levels of 1.6 +/- 2.6 pg/ml. Prepubertal boys have estradiol levels of 0.4 + 1.1 pg/ml. Estradiol had a diurnal variation in girls and boys, with the trough occurring 08.00-20.00 h in girls, and 12.00-20.00 h in boys. We confirm that estradiol levels are higher in girls than boys even before physical signs of puberty, and that estradiol increases throughout puberty in girls and boys. This 10-year experience in 800 children shows the range and variability of estradiol by an ultrasensitive bioassay.

Treatment with the aromatase inhibitor letrozole during adolescence increases near-final height in boys with constitutional delay of puberty

OBJECTIVE

We investigated whether inhibition of oestrogen biosynthesis with the aromatase inhibitor, letrozole, during adolescence improves near-final height in boys with constitutional delay of puberty.

PATIENTS AND METHODS

Seventeen boys with constitutional delay of puberty were randomized to receive testosterone (T) enanthate (1 mg/kg i.m.) every 4 weeks for 6 months in combination with placebo (Pl, n = 8), or the aromatase inhibitor letrozole (Lz, 2.5 mg/day orally) (n = 9), for 12 months. After treatment, patients were followed up until near-final height. Height discrepancy was calculated as near-final height minus mid-parental target height.

MEASUREMENTS

The primary end point was the difference in near-final height between the groups treated either with T + Pl or T + Lz. Secondarily, height discrepancy and gain in height standard deviation score (SDS) were analysed in both groups.

RESULTS

Boys treated with T + Lz reached a higher mean near-final height than did boys on T + Pl (175.8 vs. 169.1 cm, respectively, P = 0.04). In T + Lz-treated boys, mean near-final height did not differ from their mid-parental target height (175.8 vs. 177.1 cm, P = 0.38), whereas in T + Pl-treated boys, mean near-final height was lower than mid-parental target height (169.1 vs. 173.9 cm, P = 0.007). T + Lz-treated boys had a greater increment in height SDS over the pretreatment height SDS than T + Pl-treated boys (+1.4 SDS vs.+0.8 SDS, P = 0.03).

CONCLUSIONS

Our findings indicate that in adolescent boys an increase in adult height can be attained by use of aromatase inhibitors.

Of mice and men: the evolving phenotype of aromatase deficiency

We are rapidly becoming aware of the importance of estrogen in maintaining virtually all facets of male health. In order for estrogens to be synthesized endogenously, the enzyme responsible for their synthesis from androgens, aromatase, must be functional. The seven known men in whom aromatase is nonfunctional all have a mutation in either exon V or IX of the CYP19 gene, which encodes aromatase. Collectively, these men are reported to have undetectable estrogen; normal to high levels of testosterone and gonadotropins; tall stature with delayed skeletal maturation and epiphyseal closure; osteoporosis; impaired lipid and insulin metabolism; and impaired reproductive function. The aromatase knockout mouse presents with a phenotype that is similar in many aspects and provides a valuable tool with which to examine and manipulate the actions of estrogen. By studying the naturally occurring aromatase-deficient humans, together with studies of the aromatase-knockout mouse, we are expanding our understanding of the essential role of estrogen in male physiology.

Sperm analysis in growth hormone-deficient adolescents previously treated with an aromatase inhibitor: Comparison with normal controls

We performed two semen analyses in each of a small cohort of 11 GH-deficient (GHD) adolescents (mean age 18.1 +/- 0.6 yrs), previously treated (mean 29 months prior) with either GH alone or GH and an aromatase inhibitor (anastrozole) for 12 months and compared their data with those of 10 healthy controls (mean age 18.7 +/- 1.8 yrs). Although some adolescents had lower sperm parameters as compared to adult reference values, mean sperm concentrations, motility, and morphology were comparable among the 3 groups, suggestive that this small group of GHD adolescents previously treated with anastrozole has descriptively similar sperm parameters as other GHD and GH-sufficient adolescent controls.