Use of aromatase inhibitors in children and adolescents: what's new?

Aromatase Inhibitors May Increase the Risk of Cardiometabolic Complications in Adolescent Boys

INTRODUCTION

Aromatase inhibitors (AIs) are increasingly used in children and adolescents to augment adult height. The aim of this study was to investigate the effects AIs have on cardiac morphology, functions and their relation to several metabolic parameters in adolescent boys.

METHODS

Three groups matched for sex (boys, n = 67), age (median age 13.5 years), weight, height, body mass index, and puberty stages were enrolled: (i) Group 1: 23 patients using AIs (only AI (n = 6) or in combination with growth hormone (GH) (n = 17)) for at least 6 months; (ii) Group 2: 22 patients using only GH, and (iii) Group 3: 22 healthy boys. Two-dimensional, M-mode conventional Doppler and tissue Doppler examinations of the left ventricle (LV) were performed. Bioelectrical bioimpedance analyses was conducted and follicle-stimulating hormone, luteinizing hormone, total testosterone, lipid, and hemogram parameters were obtained.

RESULTS

Patients in Group 1 had significantly higher serum total testosterone (p < 0.001) and hemoglobin (p < 0.001) levels, fat free mass (p = 0.005), LV mass (LVM) (p = 0.002), as well as increased LV posterior wall diameter (LVPWD) (p = 0.002), interventricular septum diameter (IVSD) (p = 0.019), and myocardial systolic wave velocity (Sm) (p = 0.020) compared to the two other control groups. No significant differences were observed in terms of diastolic and systolic functions and lipid profiles (p > 0.05). There were positive correlations between total testosterone, hemoglobin levels, LVM, LVPWD and IVSD (p < 0.05).

CONCLUSION

Increased LVM, LVPWD, IVSD and Sm of patients receiving AI therapy in comparison to the control groups, and the significant correlations of these parameters with total testosterone and hemoglobin levels were determined as potential side effects of AIs. These findings emphasize the need of routine cardiac follow-up in patients using AIs.

Multidisciplinary Clinical Considerations in the Treatment of Pediatric Epithelial Ovarian Cancer

BACKGROUND

Epithelial ovarian cancers are a rare subset of the less than 1% of ovarian cancers diagnosed in children. This case highlights considerations when caring for these patients.

CASE

Evaluation of a 12-year-old postmenarchal girl who presented with suprapubic pain revealed a solid/cystic pelvic mass involving bilateral adnexa and elevated Cancer Antigen 125 (CA-125) level. Diagnostic laparoscopy pathology confirmed low-grade papillary serous ovarian carcinoma. Treatment involved surgical tumor debulking, hysterectomy, bilateral salpingo-oophorectomy, and omentectomy; adjuvant chemotherapy with no residual disease, and normalization of Cancer Antigen 125 (CA-125) level; and an aromatase inhibitor for maintenance.

SUMMARY AND CONCLUSION

In children with adult-type gynecologic cancers necessitating treatments including surgical sterilization and hormone-modulating therapy, psychological support and developmentally informed collaboration between adult and pediatric services is essential. Clinical decisions for long-term bone and sexual health present opportunities for future research.

Off-label use of letrozole in Chinese short pubertal boys: Effectiveness, safety, and exposure-response analysis

AIMS

Recently, letrozole has been used off-label to treat short pubertal boys. The experience on letrozole effectiveness and safety has been obtained primarily from Caucasian children. A simple extrapolation of the data to Chinese paediatric populations is questionable because of the substantial ethnic differences between the two populations. Therefore, the present study aimed to determine the effectiveness and safety of letrozole use in Chinese short pubertal boys as well as to establish an exposure-response relationship.

METHODS

Forty-one Chinese boys were included in the study. Patients were given letrozole tablets (2.5 mg) once daily in combination with growth hormone, and follow-up visits were made after 1, 3, 6 and 12 months of treatment. Plasma samples were taken from clinical examinations and analysed using high performance liquid chromatography with fluorescence detection.

RESULTS

After 1 year of treatment, 35 (88%) boys showed increased predicted adult heights. However, possible adverse drug reactions were seen in nine boys (22%). Predicted adult heights increased significantly from 168.4 ± 3.7 to 173.0 ± 4.2 cm, while oestrogen levels dropped from 33.2 ± 7.4 to 21.6 ± 7.3 pg/mL. Increments in predicted adult height were significantly correlated with trough letrozole concentrations (r = 0.39, P = .01).

CONCLUSION

Letrozole treatment in Chinese pubertal populations should be further optimized, and more personalized therapies should be developed.

Characterization of letrozole in human hair using LC-MS/MS and confirmation by LC-HRMS: Application to a doping case

Letrozole is a reversible aromatase inhibitor, used in the treatment of hormone-dependent woman cancer. No indication for medical use is available for men. In recent years, several cases of doping with letrozole have been observed, especially among high level athletes. Aromatase inhibitors reverse the harmful effects (feminizing) of the abuse of anabolic androgenic steroids. Letrozole is included on the list of products prohibited in- and out-competition by the World Anti-Doping Agency, under section S4.1. The aim of the present work was to develop a specific method to identify letrozole in human hair of a male amateur athlete by LC-MS/MS and confirmation by LC-HRMS, after incubation of 20 mg of matrix in 1 mL of methanol. The chromatographic separation was performed using a reverse phase column HSS C18 with a gradient elution of 15 min (from 87% to 5% of formate buffer adjusted to pH 3). Linearity was observed from 1 to 1000 pg/mg (r² = 0.9999), after spiking blank hair with the corresponding amounts of letrozole. The limit of detection was estimated at 0.5 pg/mg and the lower limit of quantification was the first point of the calibration curve, i.e. 1 pg/mg. The precision was lower than 20% and there was no interference with the analytes by chemicals or any extractable endogenous materials present in hair. Letrozole was identified in the male amateur athlete hair at 310 pg/mg (segment 0-2 cm) and 245 pg/mg (segment 2-4 cm).

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.

Prevention of Recurrent Mucinous Borderline Ovarian Tumor with Aromatase Inhibitor

BACKGROUND

Aromatase inhibitors (AIs) are used for estrogen-modulated conditions. Some borderline ovarian tumors (BOT) express estrogen receptors. We present 2 cases of progression from mucinous cystadenoma to mucinous BOT (mBOT) after prior cystectomies in whom an AI was used with recurrence prevention.

CASES

Two patients underwent laparoscopic ovarian cystectomy for mucinous cystadenoma. Serial imaging demonstrated recurrent ovarian cysts for which both underwent fertility sparing surgery (FSS) with ovarian cystectomy for mBOT. Both patients were initiated on an AI and have been without recurrence.

SUMMARY AND CONCLUSION

BOT predominantly occur in reproductive aged females. FSS with cystectomy is an option, but recurrence occurs in 12-36% of cases. The use of AI in prevention of recurrent BOT shows promise, and more studies are needed to explore this treatment.

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.

The use of aromatase inhibitors in boys with short stature: what to know before prescribing?

Aromatase is a cytochrome P450 enzyme (CYP19A1 isoform) able to catalyze the conversion of androgens to estrogens. The aromatase gene mutations highlighted the action of estrogen as one of the main regulators of bone maturation and closure of bone plate. The use of aromatase inhibitors (AI) in boys with short stature has showed its capability to improve the predicted final height. Anastrozole (ANZ) and letrozole (LTZ) are nonsteroidal inhibitors able to bind reversibly to the heme group of cytochrome P450. In this review, we describe the pharmacokinetic profile of both drugs, discussing possible drug interactions between ANZ and LTZ with other drugs. AIs are triazolic compounds that can induce or suppress cytochrome P450 enzymes, interfering with metabolism of other compounds. Hydroxilation, N-dealkylation and glucoronidation are involved in the metabolism of AIs. Drug interactions can occur with azole antifungals, such as ketoconazole, by inhibiting CYP3A4 and by reducing the clearance of AIs. Antiepileptic drugs (lamotrigine, phenobarbital, and phenytoin) also inhibit aromatase. Concomitant use of phenobarbital or valproate has a synergistic effect on aromatase inhibition. Therefore, it is important to understand the pharmacokinetics of AIs, recognizing and avoiding possible drug interactions and offering a safer prescription profile of this class of aromatase inhibitors. Arch Endocrinol Metab. 2017;61(3):391-7.

Disruption of aromatase homeostasis as the cause of a multiplicity of ailments: A comprehensive review

Human health is beset with a legion of ailments, which is exacerbated by lifestyle errors. Out of the numerous enzymes in human body, aromatase, a cytochrome P450 enzyme is particularly very critical. Occurring at the crossroads of multiple signalling pathways, its homeostasis is vital for optimal health. Unfortunately, medications, hormone therapy, chemical additives in food, and endocrine-disrupting personal care products are oscillating the aromatase concentration beyond the permissible level. As this enzyme converts androgens (C19) into estrogens (C18), its agitation has different outcomes in different genders and age groups. Some common pathologies associated with aromatase disruption include breast cancer, prostate cancer, polycystic ovary syndrome (PCOS), endometriosis, osteoporosis, ovarian cancer, gastric cancer, pituitary cancer, Alzheimer's disease, schizophrenia, male hypogonadism, and transgender issues. Several drugs, cosmetics and pesticides act as the activators and suppressors of this enzyme. This carefully-compiled critical review is expected to increase public awareness regarding the threats resultant of the perturbations of this enzyme and to motivate researchers for further investigation of this field.

Novel approaches to short stature therapy

Besides growth hormone, several pharmaceutical products have been investigated for efficacy and safety in increasing short term growth or adult height. Short-term treatment with testosterone esters in boys with constitutional delay of growth and puberty is efficacious in generating secondary sex characteristics and growth acceleration. The addition of oxandrolone to growth hormone (GH) in Turner syndrome has an additive effect on adult height gain. Treatment with GnRH analogs is the established treatment of central precocious puberty, and its addition to GH therapy appears effective in increasing adult height in GH deficient children, and possibly short children born SGA or with SHOX deficiency, who are still short at pubertal onset. Aromatase inhibitors appear effective in several rare disorders, but their value in increasing adult height in early pubertal boys with GH deficiency or idiopathic short stature is uncertain. A trial with a C-natriuretic peptide analog offers hope for children with achondroplasia.

Height augmentation in 11β-hydroxylase deficiency congenital adrenal hyperplasia

Context

11β-hydroxylase deficiency is the second most common form of congenital adrenal hyperplasia. Untreated, this enzyme deficiency leads to virilization, hypertension, and significant height impairment.

Patient

We describe a patient from abroad who first presented to us at age 7 years for follow-up of ambiguous genitalia. He had been investigated and treated in Pakistan at 3-years-of-age following presentation for bilateral cryptorchidism. He was found to have 46, XX karyotype, elevated 17-OH progesterone and was diagnosed with congenital adrenal hyperplasia. In Pakistan, the patient had abdominal hysterectomy, bilateral salpingoophrectomy, and was started on corticosteroid replacement. At 7 years, shortly after immigrating to Canada, height was 138 cm and BMI 19.3 kg/m² (+2.9 SDS and +1.7 SDS, respectively, male growth chart) and blood pressure was greater than the 99th percentile for age and height. The patient had Prader stage III - IV genital anatomy. Bone age was significantly advanced, yielding a severely compromised predicted final adult height. Biochemical evaluation was consistent with 11β-hydroxylase deficiency congenital adrenal hyperplasia.

Intervention and outcome

In an attempt to improve final height, in addition to glucocorticoid replacement, this patient was treated with recombinant growth hormone and a third generation aromatase inhibitor (Letrozole) with an improvement in final height attained as compared with predicted height.

Conclusions

This case of a 46,XX patient raised as male with congenital adrenal hyperplasia due to 11β-hydroxylase deficiency highlights a number of unique and difficult treatment challenges; specifically, the role of new therapeutic options for optimization of growth in the context of prior suboptimal disease management.

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.