Pathophysiology of radiation-induced growth hormone deficiency: efficacy and safety of GH replacement

Developments in the Management of Growth Hormone Deficiency: Clinical Utility of Somapacitan

Growth hormone (GH) replacement therapy for growth hormone deficiency (GHD) in children and adults has for over 25 years, until recently, been administered as daily injections. This daily treatment regimen often incurs a burden to patients and caregivers, leading to high rates of non-adherence and, consequently, decreased treatment efficacy outcomes. To address this shortcoming, long-acting growth hormones (LAGHs) have been developed with the aim of reducing the burden of daily injections, thereby potentially improving treatment adherence and outcomes. Somapacitan (Sogroya®) (Novo Nordisk, Bagsværd, Denmark) is a LAGH currently approved for the treatment of adult and childhood GHD (AGHD and CGHD, respectively) in several countries. Other LAGHs, such as somatrogon (Ngenla®) (Pfizer, New York, United States) and lonapegsomatropin/TransCon GH (Skytrofa®) (Ascendis Pharma, Copenhagen, Denmark), are also currently approved and available for the treatment of CGHD in several countries. In this review, we will consider the method of protraction, pharmacokinetics (PK) and pharmacodynamics (PD), efficacy, and safety results of somapacitan in adult and pediatric trials and how these characteristics differ from those of the other aforementioned LAGHs. Additionally, the administration of somapacitan and timing of measurement of serum insulin-like growth factor-I (IGF-I) levels are summarized. Information on administration, advice on missed doses, and clinical guidelines are discussed, as well as identifying which patients are suitable for somapacitan therapy, and how to monitor and adjust dosing whilst on therapy.

Growth hormone after CNS tumor diagnosis: the fundamentals, fears, facts, and future directions

Growth hormone deficiency (GHD) may occur in pediatric patients with central nervous system (CNS) tumors at initial tumor presentation or later as treatment-related sequelae. While it is well recognized that growth hormone (GH) has beneficial effects on growth and endocrinopathies, there's often hesitancy by clinicians to initiate GH therapy for GHD after CNS tumor diagnosis due to the perceived increased risk of tumor recurrence. The available data is described here and based on this review, there is no evidence of increased risk of tumor recurrence or secondary malignancy in patients treated with GH after CNS tumor diagnosis. Further understanding of tumor biology and presence of downstream GH targets including insulin-like growth factor-1 (IGF-1) and insulin receptor activity is still needed.

Isolated anterior pituitary dysfunction in adulthood

Hypopituitarism is defined as a complete or partial deficiency in one or more pituitary hormones. Anterior hypopituitarism includes secondary adrenal insufficiency, central hypothyroidism, hypogonadotropic hypogonadism, growth hormone deficiency and prolactin deficiency. Patients with hypopituitarism suffer from an increased disability and sick days, resulting in lower health status, higher cost of care and an increased mortality. In particular during adulthood, isolated pituitary deficits are not an uncommon finding; their clinical picture is represented by vague symptoms and unclear signs, which can be difficult to properly diagnose. This often becomes a challenge for the physician. Aim of this narrative review is to analyse, for each anterior pituitary deficit, the main related etiologies, the characteristic signs and symptoms, how to properly diagnose them (suggesting an easy and reproducible step-based approach), and eventually the treatment. In adulthood, the vast majority of isolated pituitary deficits are due to pituitary tumours, head trauma, pituitary surgery and brain radiotherapy. Immune-related dysfunctions represent a growing cause of isolated pituitary deficiencies, above all secondary to use of oncological drugs such as immune checkpoint inhibitors. The diagnosis of isolated pituitary deficiencies should be based on baseline hormonal assessments and/or dynamic tests. Establishing a proper diagnosis can be quite challenging: in fact, even if the diagnostic methods are becoming increasingly refined, a considerable proportion of isolated pituitary deficits still remains without a certain cause. While isolated ACTH and TSH deficiencies always require a prompt replacement treatment, gonadal replacement therapy requires a benefit-risk evaluation based on the presence of comorbidities, age and gender of the patient; finally, the need of growth hormone replacement therapies is still a matter of debate. On the other side, prolactin replacement therapy is still not available. In conclusion, our purpose is to offer a broad evaluation from causes to therapies of isolated anterior pituitary deficits in adulthood. This review will also include the evaluation of uncommon symptoms and main etiologies, the elements of suspicion of a genetic cause and protocols for diagnosis, follow-up and treatment.

The multiple roles of GH in neural ageing and injury

Advanced age is typically associated with a decrease in cognitive function including impairment in the formation and retention of new memories. The hippocampus is critical for learning and memory, especially spatial learning, and is particularly affected by ageing. With advanced age, multiple neural components can be detrimentally affected including a reduction in the number of neural stem and precursor cells, a decrease in the formation of adult born neurons (neurogenesis), and deficits in neural circuitry, all of which ultimately contribute to impaired cognitive function. Importantly, physical exercise has been shown to ameliorate many of these impairments and is able to improve learning and memory. Relevantly, growth hormone (GH) is an important protein hormone that decreases with ageing and increases following physical exercise. Originally described due to its role in longitudinal growth, GH has now been identified to play several additional key roles, especially in relation to the brain. Indeed, the regular decrease in GH levels following puberty is one of the most well documented components of neuroendocrine ageing. Growth hormone deficiency (GHD) has been described to have adverse effects on brain function, which can be ameliorated via GH replacement therapy. Physical exercise has been shown to increase circulating GH levels. Furthermore, we recently demonstrated the increase in exercise-mediated GH is critical for improved cognitive function in the aged mouse. Here we examine the multiple roles that GH plays, particularly in the aged brain and following trauma, irradiation and stroke, and how increasing GH levels can ameliorate deficits in cognition.

Growth Hormone replacement therapy in pediatric brain tumor survivors

Brain tumors are the most frequent type of solid neoplasms in children with a recognized 5-year survival rate between 57 and 65%. The survival rate progressively increased in the last few years, due to the improvements in their treatment based on chemotherapy, radiotherapy, and surgery. At the same time, at long term follow-up, clinicians should carefully evaluate comorbidities and long term sequelae secondary to the disease and its treatment. Growth Hormone Deficiency (GHD) is an endocrinopathy commonly found among pediatric cancer survivors, with a negative effect on the child's final height and entire metabolism. GH replacement therapy (GHRT), with a synthetic hormone analog, may improve the growth rate and finally adult height, ameliorating the quality of life after cancer treatment. However, in clinical practice, GHRT is adopted with caution for fear of cancer recurrence or the onset of second malignancies. In our review, we perform a focus on the GH structure and function, comparing benefits and risks of GHRT, derived from the analysis of the data currently available in the literature.

Dual Characters of GH-IGF1 Signaling Pathways in Radiotherapy and Post-radiotherapy Repair of Cancers

Radiotherapy remains one of the most important cancer treatment modalities. In the course of radiotherapy for tumor treatment, the incidental irradiation of adjacent tissues could not be completely avoided. DNA damage is one of the main factors of cell death caused by ionizing radiation, including single-strand (SSBs) and double-strand breaks (DSBs). The growth hormone-Insulin-like growth factor 1 (GH-IGF1) axis plays numerous roles in various systems by promoting cell proliferation and inhibiting apoptosis, supporting its effects in inducing the development of multiple cancers. Meanwhile, the GH-IGF1 signaling involved in DNA damage response (DDR) and DNA damage repair determines the radio-resistance of cancer cells subjected to radiotherapy and repair of adjacent tissues damaged by radiotherapy. In the present review, we firstly summarized the studies on GH-IGF1 signaling in the development of cancers. Then we discussed the adverse effect of GH-IGF1 signaling in radiotherapy to cancer cells and the favorable impact of GH-IGF1 signaling on radiation damage repair to adjacent tissues after irradiation. This review further summarized recent advances on research into the molecular mechanism of GH-IGF1 signaling pathway in these effects, expecting to specify the dual characters of GH-IGF1 signaling pathways in radiotherapy and post-radiotherapy repair of cancers, subsequently providing theoretical basis of their roles in increasing radiation sensitivity during cancer radiotherapy and repairing damage after radiotherapy.

GH deficiency in cancer survivors in the transition age: diagnosis and therapy

BACKGROUND

Survival rates among childhood cancer survivors (CCSs) have significantly risen in the last 40 years due to substantial improvements in treatment protocols. However, this improvement has brought with it serious late effects that frequently involve the endocrine system. Of the endocrine disorders, GH deficiency (GHD) is the most common among CCSs as a consequence of a history of cancers, surgery, and/or radiotherapy involving the hypothalamo-pituitary region.

METHODS

A comprehensive search of English language articles regardless of age was conducted in the MEDLINE database between December 2018 and October 2019. We selected all studies on GH therapy in CCSs during the transition age regarding the most challenging topics: when to retest; which diagnostic tests and cut-offs to use; when to start GH replacement therapy (GHRT); what GH dose to use; safety; quality of life, compliance and adherence to GHRT; interactions between GH and other hormonal replacement treatments.

RESULTS

In the present review, we provide an overview of the current clinical management of challenges in GHD in cancer survivors in the transition age.

CONCLUSIONS

Endocrine dysfunction among CCSs has a high prevalence in the transition age and increase with time. Many endocrine disorders, including GHD, are often not diagnosed or under-diagnosed, probably due to the lack of specialized centers for the long-term follow-up. Therefore, it is crucial that transition specialized clinics should be increased in terms of number and specific skills in order to manage endocrine disorders in adolescence, a delicate and complex period of life. A multidisciplinary approach, also including psychological counseling, is essential in the follow-up and management of these patients in order to minimize their disabilities and maximize their quality of life.

Are hypothyroidism and hypogonadism clinically relevant in patients with malignant gliomas? A longitudinal trial in patients with glioma

BACKGROUND

So far, the development and course of therapy-induced deficiencies in hypothalamic-pituitary hormones in adult patients with malignant gliomas has not received much attention. However, such deficiencies may impact patient's quality of life substantially.

METHODS

In this monocentric longitudinal trial, we examined hormonal levels of TSH, T3, T4, fT3, fT4, FSH, LH, testosterone, estradiol and prolactin in patients with malignant high grade gliomas before the start of radiochemotherapy (RCT), at the end of RCT and then every three months for newly diagnosed patients and every six months in patients diagnosed more than two years before study inclusion. Growth hormone was not measured in this trial.

RESULTS

436 patients (198 female, 238 male) with high-grade gliomas, aged 19-83 years (median 50 years), were included in this study. Low levels of thyroid hormones were observed in around 10% of patients within the first six months of follow up and increasingly after 36 months. Half of premenopausal women at study entry developed premature menopause, 35% showed hyperprolactinemia. Low testosterone levels were measured in 37% of men aged less than 50 years and in 35/63 (55%) of men aged 50 years or older.

DISCUSSION

The results of this study show that a significant percentage of patients with malignant gliomas develop hormonal deficiencies mandating regular clinical follow up, state of the art counseling and if clinically necessary substitution therapy.

Olfactory Memory Impairment Differs by Sex in a Rodent Model of Pediatric Radiotherapy

Although an effective treatment for pediatric brain tumors, cranial radiation therapy (CRT) damages surrounding healthy tissue, thereby disrupting brain development. Animal models of pediatric CRT have primarily relied on visual tasks to assess cognitive impairment. Moreover, there has been a lack of sex comparisons as most research on the cognitive effects of pediatric CRT does not include females. Therefore, we utilized olfaction, an ethologically relevant sensory modality, to assess cognitive impairment in an animal model of CRT that included both male and female mice. Specifically, we used the novel odor recognition (NOdorR) task with social odors to test recognition memory, a cognitive parameter that has been associated with olfactory neurogenesis, a form of cellular plasticity damaged by CRT. In addition to odor recognition memory, olfactory ability or discrimination of non-social and social odors were assessed both acutely and 3 months after CRT. Magnetic resonance imaging (MRI) and histology were performed after behavioral testing to assess long-term damage by CRT. Long-term but not acute radiation-induced impairment in odor recognition memory was observed, consistent with delayed onset of cognitive impairment in human patients. Males showed greater exploration of social odors than females, but general exploration was not affected by irradiation. However, irradiated males had impaired odor recognition memory in adulthood, compared to non-irradiated males (or simply male controls). Female olfactory recognition memory, in contrast, was dependent on estrus stage. CRT damage was demonstrated by (1) histological evaluation of olfactory neurogenesis, which suggested a reduction in CRT versus control, and (2) imaging analyses which showed that the majority of brain regions were reduced in volume by CRT. Specifically, two regions involved in social odor processing (amygdala and piriform cortex) were damaged by cranial irradiation in males but not females, paralleling olfactory recognition findings.

GH deficiency in adult survivors of childhood cancer

Childhood cancer survivors (CCS) are a fast growing population, but late adverse effects of cancer therapies are not rare. In CCS treated with cranial radiotherapy, growth hormone deficiency (GHD) is a well-known occurrence and the potential impact of GH replacement therapy on the global outcome of CCS is under continuous evaluation. In the present review, we discuss advantages and disadvantages of GH replacement therapy in survivors of pediatric malignancies, taking into consideration the different reasons for treating GHD during childhood or adult life. It is doubtless that GH treatment is advisable to obtain a normal growth in pediatric patients. As far as the beginning/continuation of the replacement therapy in adult age is concerned, contrasting results have been reported in literature. The suggestion is that the decision to treat adult CCS should be taken after careful evaluation of each patient's clinical history and of the potential side effects, in agreement with the patients.

Growth hormone exposure as a risk factor for the development of subsequent neoplasms of the central nervous system: a report from the childhood cancer survivor study

CONTEXT

Cranial radiation therapy (CRT) predisposes to GH deficiency and subsequent neoplasms (SNs) of the central nervous system (CNS). Increased rates of SNs have been reported in GH-treated survivors.

OBJECTIVE

The objective of the study was to evaluate the association between GH treatment and the development of CNS-SNs.

DESIGN

The study was designed with a retrospective cohort with longitudinal follow-up.

SETTING

The setting of the study was multiinstitutional.

PARTICIPANTS

A total of 12 098 5-year pediatric cancer survivors from the Childhood Cancer Survivor Study, diagnosed with cancer prior to age 21 years, of whom 338 self-reported GH treatment, which was verified through medical record review.

INTERVENTIONS

INTERVENTIONS included subject surveys, medical records abstraction, and pathological review.

OUTCOME MEASURES

Incidence of meningioma, glioma, and other CNS-SNs was measured.

RESULTS

Among GH-treated survivors, 16 (4.7%) developed CNS-SN, including 10 with meningioma and six with glioma. Two hundred three survivors without GH treatment (1.7%) developed CNS-SN, including 138 with meningioma, 49 with glioma, and 16 with other CNS-SNs. The adjusted rate ratio in GH-treated compared with untreated survivors for development of any CNS-SN was 1.0 [95% confidence interval (CI) 0.6-1.8, P = .94], for meningiomas, 0.8 (95% CI 0.4-1.7, P = .61), and for gliomas, 1.9 (95% CI 0.7-4.8, P = .21). Factors associated with meningioma development included female gender (P = .001), younger age at primary cancer diagnosis (P < .001), and CRT/longer time since CRT (P < .001). Glioma was associated with CRT/shorter time since CRT (P < .001).

CONCLUSIONS

There was no statistically significant increased overall risk of the occurrence of a CNS-SN associated with GH exposure. Specifically, occurrence of meningiomas and gliomas were not associated with GH treatment.

Endocrinopathies in survivors of childhood neoplasia

Advancements in cancer treatments have increased the number of survivors of childhood cancers. Endocrinopathies are common complications following cancer therapy and may occur decades later. The objective of the current review is to address the main endocrine abnormalities detected in childhood cancer survivors including disorders of the hypothalamic-pituitary axis, thyroid, puberty, gonads, bone, body composition, and glucose metabolism.

Baseline characteristics and effects of ten years of growth hormone (GH) replacement therapy in adults previously treated with pituitary irradiation

CONTEXT

Little is known of the importance of previous irradiation therapy for baseline characteristics and responsiveness to GH replacement in GH deficient (GHD) adults.

OBJECTIVE/DESIGN/PATIENTS

In this prospective, single-centre, open-label study, the effects of 10-year GH replacement were determined in 18 GHD adults that had previously received conventional external fractionated pituitary irradiation therapy (IRR group) and 18 non-irradiated GHD patients (non-IRR group). All patients had adult onset disease and complete deficiency of anterior pituitary hormones and both groups were comparable in terms of age, gender, body mass index (BMI), and waist:hip ratio.

RESULTS

At baseline, IRR patients had higher serum triglyceride (TG) and insulin levels and lower high density lipoprotein (HDL)-cholesterol (HDL-C) level than non-IRR patients (all p<0.05). The 10-year GH replacement improved body composition, bone mass and serum lipid profile without any between-group differences, except for a marginally more beneficial response in serum TG level in the IRR patients. After 10 years, there was no between-group difference in any variable after correction for a higher replacement dose of glucocorticoids in the IRR patients at study end using an analysis of covariance. During the 10-year GH replacement, 5 IRR patients suffered from vascular events (2 fatal) whereas only one non-fatal vascular event occurred in the non-IRR patients.

CONCLUSIONS

IRR patients with GHD display a more severely impaired cardiovascular risk profile at baseline, which was reversed by the 10-year GH replacement after correction for the higher glucocorticoid dose at study end. However, vascular events occurred more frequently in the IRR patients.

Radiotherapy-induced hypopituitarism: a review

Hypopituitarism is a disorder caused by impaired hormonal secretions from the hypothalamic-pituitary axis. Radiotherapy is the most common cause of iatrogenic hypopituitarism. The hypothalamic-pituitary axis inadvertently gets irradiated in patients receiving prophylactic cranial radiotherapy for leukemia, total body irradiation and radiotherapy for intracranial, base skull, sinonasal and nasopharyngeal tumors. Radiation-induced hypopituitarism (RIH) is insidious, progressive and largely nonreversible. Mostly, RIH involves one hypothalamic-pituitary axis; however, multiple hormonal axes deficiency starts developing at higher doses. Although the clinical effects of the hypopituitarism are more profound in children and young adults, its implications in older adults are being increasingly recognized. The risk continues to persist or increase up to 10 years following radiation exposure. The clinical management of hypopituitarism is challenging both for the patients and healthcare providers. Here we have reviewed the scale of the problem, the risk factors and the management of RIH.

Growth hormone: the expansion of available products and indications

Growth hormone is a widely used hormone. This article describes its historical use, current indications and studies for possible future uses.

Postradiation therapy hypopituitarism

The increasing use of radiation treatment for head and neck cancers and other tumors, including pituitary adenomas, from the mid-20th Century onwards led to the recognition that pituitary function may be affected - often leading to some degree of pituitary insufficiency. Our knowledge is mostly based on observational or retrospective rather than randomized prospective studies. The various axes may be impacted at the hypothalamic or pituitary levels, or both. Some axes - the somatotropic and gonadotropic - appear to be especially vulnerable to radiation damage and may be affected quite early, whereas posterior pituitary function is rarely affected. Increased use of stereotactic radiosurgery, which focuses the radiation dose on the abnormal tissue, may be expected to reduce the impact on normal pituitary function, but such studies that are available are, as yet, relatively short term. Prospective studies of the effect of stereotactic radiosurgery on pituitary function would be valuable.

Rational design of HIV vaccine and microbicides: report of the EUROPRISE annual conference

EUROPRISE is a Network of Excellence sponsored from 2007 to 2011 by the European Commission within the 6th Framework Program. The Network encompasses a wide portfolio of activities ranging from an integrated research program in the field of HIV vaccines and microbicides to training, dissemination and advocacy. The research program covers the whole pipeline of vaccine and microbicide development from discovery to early clinical trials. The Network is composed of 58 partners representing more than 65 institutions from 13 European countries; it also includes three major pharmaceutical companies (GlaxoSmithKline, Novartis and Sanofi-Pasteur) involved in HIV microbicide and vaccine research. The Network displays a dedicated and informative web page: http://www.europrise.org. Finally, a distinguishing trait of EUROPRISE is its PhD School of students from across Europe, a unique example in the world of science aimed at spreading excellence through training. EUROPRISE held its second annual conference in Budapest in November, 2009. The conference had 143 participants and their presentations covered aspects of vaccine and microbicide research, development and discovery. Since training is a major task of the Network, the students of the EUROPRISE PhD program summarized certain presentations and their view of the conference in this paper.

Somatotropin in the treatment of growth hormone deficiency and Turner syndrome in pediatric patients: a review

Growth hormone (GH), also known as somatotropin, is a peptide hormone that is synthesized and secreted by the somatotrophs of the anterior pituitary gland. The main action of GH is to stimulate linear growth in children; however, it also fosters a healthy body composition by increasing muscle and reducing fat mass, maintains normal blood glucose levels, and promotes a favorable lipid profile. This article provides an overview of the normal pathophysiology of GH production and action. We discuss the history of GH therapy and the development of the current formulation of recombinant human GH given as daily subcutaneous injections. This paper reviews two of the longest standing FDA-approved indications for GH treatment, GH deficiency and Turner syndrome. We will highlight the pathogenesis of these disorders, including presentations, presumed mechanism(s) for the associated short stature, and diagnostic criteria, with a review of stimulation test benefits and pitfalls. This review also includes current recommendations for GH therapy to help maximize final height in these children, as well as data demonstrating the efficacy and safety of GH treatment in these populations.

Growth hormone: the expansion of available products and indications

Growth hormone is a widely used hormone. This article describes its historical use, current indications and studies for possible future uses.

Malignant tumors of the nasal cavity and paranasal sinuses: long-term outcome and morbidity with emphasis on hypothalamic-pituitary deficiency

PURPOSE

To evaluate the long-term outcome after surgery and radiotherapy for patients with sinonasal cancer and assess late toxicity, with special emphasis on hypothalamic-pituitary dysfunction.

METHODS AND MATERIALS

A retrospective analysis of 168 patients treated for sinonasal cancer in a single institute between 1986 and 2006. A more detailed analysis was performed on a subgroup of 76 patients with adenocarcinoma or squamous cell carcinoma treated with curative intent. Long-term survivors were evaluated for late toxicity by a multidisciplinary team using the late effects of normal tissues (LENT SOMA) scoring system. Additional endocrinologic tests were performed for assessment of hypothalamic-pituitary function.

RESULTS

Five-year actuarial local control and overall survival rates were 62% and 35% for all patients and 64% and 42% for the subgroup with squamous cell carcinoma and adenocarcinoma. In multivariate analysis, T stage was the only significant factor predicting local relapse (79% at 5 years for T1-T3 vs. 53% for T4; p = 0.006). Sinonasal mucosal melanomas had the highest rate of regional failure (33% at 5 years). Thirteen of 21 patients (62%) evaluated at the late morbidity clinic had hormonal disturbances, of whom 5 (24%) had definitive evidence of hypopituitarism with multiple hormonal deficiencies.

CONCLUSION

Local failure is the dominant cause of treatment failure for patients with sinonasal cancer, with T4 stage the only independent predictor. Because of a high rate of radiation-induced hypopituitarism, we recommend endocrinologic surveillance for these patients.

Growth hormone treatment and cancer risk

Increasing numbers of children receive growth hormone (GH) to treat a range of growth disorders, including those rendered GH deficient (GHD) by tumors or their treatment. Young persons with persistent growth hormone deficiency (GHD) and adults with severe GHD are also eligible to receive GH treatment. As in vitro and in vivo studies and epidemiologic observations provide some evidence that the GH--insulin like growth factor-I (IGF-I) axis is associated with tumorigenesis, it is important to assess, in practice, the incidence of tumors related to GH treatment. Reassuringly, surveillance studies in large cohorts of children and in smaller cohorts of adults indicate that GH is not associated with an increased incidence of tumor occurrence or recurrence. Nevertheless, all children who have received GH, in particular cancer survivors and those receiving GH in adulthood, should be in surveillance programs to assess whether an increased rate od late-onset and rare tumours may occur.

The oncogenic potential of growth hormone

A growing body of recent literature indicates that in addition to an essential role in growth and development, growth hormone may also play a more sinister role in oncogenic transformation and neoplastic progression. Here we review the accumulating evidence implicating growth hormone in the development and progression of cancer and describe what is known of the mechanisms utilised by this hormone in neoplastic transformation.