SOCIETY FOR ENDOCRINOLOGY ENDOCRINE EMERGENCY GUIDANCE: Acute management of the endocrine complications of checkpoint inhibitor therapy.

Immunotherapy treatment with checkpoint inhibitors (CPI) (CTLA-4 and PD-1 inhibitors) significantly improves survival in a number of cancers. Treatment can be limited by immune-mediated adverse effects including endocrinopathies such as hypophysitis, adrenalitis, thyroiditis and diabetes mellitus. If endocrinopathies (particularly hypocortisolemia) are not recognized early, they can be fatal. The diagnosis and management of endocrinopathies can be complicated by simultaneous multi-organ immune adverse effects. Here, we present Endocrine Emergency Guidance for the acute management of the endocrine complications of checkpoint inhibitor therapy, the first specialty-specific guidance with Endocrinology, Oncology and Acute Medicine input and endorsed by the Society for Endocrinology Clinical Committee. We present algorithms for management: endocrine assessment and management of patients in the first 24 hours who present life-threateningly unwell (CTCAE grade 3-4) and the appropriate management of mild-moderately unwell patients (CTCAE grade 1-2) presenting with features compatible with an endocrinopathy. Other important considerations in relation to hypohysitis and the maintenance of glucocorticoid therapy are discussed.

Affective alterations in patients with Cushing's syndrome in remission are associated with decreased BDNF and cortisone levels.

OBJECTIVE: Affective alterations and poorer quality of life often persist in patients with Cushing's syndrome (CS) in remission. Brain-derived neurotrophic factor (BDNF) regulates the hypothalamic-pituitary-adrenal axis (HPA) and is highly expressed in brain areas controlling mood and response to stress. Our aims were to assess affective alterations after long-term remission of CS and evaluate whether they are associated with serum BDNF, salivary cortisol (SalF) and/or cortisone (SalE) concentrations. SUBJECTS AND METHODS: Thirty-six CS patients in remission (32 females/4 males; mean age (±s.d.), 48.8 ± 11.8 years; median duration of remission, 72 months) and 36 gender-, age- and BMI-matched controls were included. Beck Depression Inventory-II (BDI-II), Center for Epidemiological Studies Depression Scale (CES-D), Positive Affect Negative Affect Scale (PANAS), State-Trait Anxiety Inventory (STAI), Perceived Stress Scale (PSS) and EuroQoL and CushingQoL questionnaires were completed and measured to evaluate anxiety, depression, stress perception and quality of life (QoL) respectively. Salivary cortisol was measured using liquid chromatography/tandem mass spectrometry (LC/TMS). BDNF was measured in serum using an ELISA. RESULTS: Remitted CS patients showed worse scores in all questionnaires than controls: STAI (P < 0.001), BDI (P < 0.001), CES-D (P < 0.001), PANAS (P < 0.01), PSS (P < 0.01) and EuroQoL (P < 0.01). A decrease in BDNF was observed in CS vs controls (P = 0.038), and low BDNF was associated with more anxiety (r = -0.247, P = 0.037), depression (r = -0.249, P = 0.035), stress (r = -0.277, P = 0.019) and affective balance (r = 0.243, P = 0.04). Morning salivary cortisone was inversely associated with trait anxiety (r = -0.377, P = 0.040) and depressed affect (r = -0.392, P = 0.032) in CS patients. Delay to diagnosis was associated with depressive symptoms (BDI-II: r = 0.398, P = 0.036 and CES-D: r = 0.449, P = 0.017) and CushingQoL scoring (r = -0.460, P < 0.01). CONCLUSIONS: Low BDNF levels are associated with affective alterations in 'cured' CS patients, including depression, anxiety and impaired stress perception. Elevated levels of SalE might also be related to poor affective status in these patients.

Proopiomelanocortin interference in the measurement of adrenocorticotrophic hormone: a United Kingdom National External Quality Assessment Service study.

OBJECTIVE: It is recognized that measurement of ACTH-precursor peptides including proopiomelanocortin (POMC) has clinical utility in identifying the aetiology of Cushing's syndrome. Recent data have also demonstrated cross-reactivity of POMC in ACTH immunoassays used in clinical laboratories. The aim of this study was to assess the cross-reactivity of POMC in the main commercial immunoassays for ACTH and to survey the awareness of laboratory professionals to this potential interference. METHOD: To assess cross-reactivity, specimens containing ACTH and/or POMC were prepared by the UK National External Quality Assessment Service (UK NEQAS) [Edinburgh]. A separate interpretative exercise was also sent to participating laboratories. RESULTS: Eighty-seven laboratories measured 'total' ACTH (i.e. ACTH and/or POMC) in their assays. Cross-reactivity of POMC varied from a mean of 1·6-4·7% (reflected in a large percentage increase in measured ACTH of up to 261% due to POMC cross-reactivity) depending on the manufacturer. Major differences in the clinical interpretation of test results were observed in returned responses to the interpretative exercise. CONCLUSION: An appraisal of POMC cross-reactivity in currently available ACTH immunoassays has been achieved. Cross-reactivity was sufficient to detect ACTH precursors at concentrations that could be found in patients with ectopic ACTH syndrome. These data will assist laboratories in interpreting results when assessing the hypothalamic-pituitary-adrenal axis. Endocrinologists and laboratory professionals should be aware of the degree of cross-reactivity in ACTH immunoassay in order to minimize the risk of misinterpretation of results and/or potentially delayed treatment.

Routine measurement of plasma chromogranin B has limited clinical utility in the management of patients with neuroendocrine tumours.

OBJECTIVE: Chromogranin A (CgA) and B (CgB) are markers for monitoring disease status in patients with gastroenteropancreatic neuroendocrine tumours (NETs). These are specialized diagnostic tests often necessitating referral of specimens to a supraregional assay service (SAS) laboratory for analysis. The aim of this audit was to assess whether measurement of either plasma CgA or CgB alone provides sufficient clinical information in comparison with the current practice of measuring both markers together. DESIGN: A retrospective analysis was undertaken for all chromogranin tests requested for patients with a known NET diagnosis. Results were categorized based on whether plasma concentrations were elevated for one or both CgA and CgB. RESULTS: A total of 325 sequential patients with a NET diagnosis had plasma chromogranin levels measured during the period of review. Baseline CgA was elevated in 60·9% of patients. Isolated elevations in CgA (with normal CgB) were found in 44·9% of patients, whilst combined elevations in both CgA and CgB were found in 16% of patients. Combined CgA and CgB concentrations within the normal range were observed for 38·5% of patients. Only two patients (0·6%) had an isolated elevation in CgB at baseline. Both patients had a diagnosis of pancreatic NET and were radiologically stable. Plasma CgA and CgB corresponded with disease stage (localized vs metastatic). CgB in addition to CgA did not provide any significant improvement in diagnostic performance for identification of metastatic disease compared to CgA alone. CONCLUSIONS: Based on this NET population and specific assay performance characteristics, CgA alone provides sufficient information for the management of NET patients; the routine estimation of CgB in all patients is not informative in clinical practice.

Effective combination treatment with cabergoline and low-dose pegvisomant in active acromegaly: a prospective clinical trial.

CONTEXT: With adequate dose titration, pegvisomant normalizes IGF-I in up to 97% of patients with acromegaly. Pegvisomant is indicated for treatment-resistant disease but is expensive, particularly at a high dose. It has been used successfully in combination with somatostatin analogs. However, there are no therapeutic reports of pegvisomant in combination with dopamine agonists. Cabergoline is orally active, well-tolerated, and relatively inexpensive, and as monotherapy for acromegaly it is reported to normalize IGF-I in up to 30% of patients. OBJECTIVE: The aim of the study was to investigate the efficacy of cabergoline monotherapy and pegvisomant in combination with cabergoline to control serum IGF-I in patients with active acromegaly. Twenty-four patients were recruited into a United Kingdom, multicenter, open-label, prospective clinical trial. MAIN OUTCOME MEASURE: We measured the change in serum IGF-I. RESULTS: After 18 wk of dose titration to a maximum dose of 0.5 mg once daily, cabergoline monotherapy did not significantly reduce IGF-I (454 ± 219 baseline vs. 389 ± 192 ng/ml cabergoline), although two patients did normalize IGF-I. The addition of 10 mg pegvisomant daily for 12 wk significantly reduced IGF-I (389 ± 192 ng/ml cabergoline vs. 229 ± 101 ng/ml combination), and 68% achieved a normal IGF-I. Twelve weeks after cabergoline withdrawal, while continuing to receive pegvisomant 10 mg, only 26% of patients maintained an IGF-I within the reference range (229 ± 101 ng/ml combination vs. 305 ± 177 ng/ml pegvisomant). There were no significant changes in liver transaminases or glucose metabolism throughout the study. CONCLUSION: These data suggest that combination treatment with cabergoline and pegvisomant is more effective at reducing IGF-I levels than either cabergoline or pegvisomant monotherapy.

Serum regulates cortisol bioactivity by corticosteroid-binding globulin-dependent and independent mechanisms, as revealed by combined bioassay and physicochemical assay approaches.

CONTEXT: Corticosteroid-binding globulin (CBG) is the principal carrier of natural glucocorticoids in the circulation, and we hypothesized that it modulates glucocorticoid bioactivity (GBA). Alterations in CBG, the presence of noncortisol, naturally occurring glucocorticoids and the use of potent, synthetic glucocorticoids, all make it difficult to assess adrenal activity in-vivo; these problems can be addressed by a glucocorticoid bioassay. DESIGN AND SUBJECTS: A bioassay was developed for serum GBA and a physicochemical ultrafiltration-liquid chromatography-tandem mass spectrometry assay for free serum cortisol (FreeF). We studied individuals homozygous and heterozygous for a nonfunctioning CBG variant (CBG G237V) and healthy controls. RESULTS: FreeF concentrations were similar in healthy controls, and those with absent functional CBG, but surprisingly we found low GBA in CBG null individuals. This may suggest that CBG delivers cortisol to target cells. However, further experiments revealed that dilution of serum in the bioassay caused release of cortisol from CBG, resulting in elevated GBA measurements in all but the CBG G237V homozygotes. Furthermore, we identified a specific and potent inhibitory effect of high concentration serum on glucocorticoid sensitivity of the recipient cells used in the bioassay. Analysis of inflammatory synovial fluid, a filtrate of serum with lower CBG concentration, revealed elevated free cortisol compared to noninflammatory synovial fluid, a change not attributable to interconversion between cortisol and cortisone. CONCLUSIONS: Our findings reveal that dilution of CBG enhances cortisol release, and so bioactivity, and also that serum potently induces glucocorticoid resistance in target cells.

Changes in arterial stiffness but not carotid intimal thickness in acromegaly.

CONTEXT: Acromegaly increases cardiovascular morbidity. We tested the hypothesis that increased arterial stiffness together with left ventricular hypertrophy may be a contributory factor. PATIENTS AND DESIGN: Fifty-six patients (40 males, 54 ± 13 yr; 25 active disease, 31 in remission) and 46 healthy controls (30 males, 52 ± 13 yr) underwent measurements of aortic pulse wave velocity (PWV), carotid Doppler (IMT), echocardiography, and cardiovascular risk factors. RESULTS: Mean serum IGF-I was 323 ± 286 ng/ml (sd score 1.8 ± 1.9) in all patients. Age, body mass index, diastolic blood pressure (BP), and lipid levels were similar comparing patients and controls. Systolic BP (130.8 ± 19.9 vs. 122 ± 14 mm Hg controls, P < 0.01) and PWV (11.7 ± 3.8 vs. 9.7 ± 2.8 m/sec, 95% confidence interval -3.4 to -0.7, P <0.01) were higher in patients than controls. Regression analysis revealed age, presence of acromegaly, systolic BP, and body mass index, inversely, as significantly and independently associated with PWV. No difference in carotid IMT was seen (0.8 ± 0.2 patients vs. 0.7 ± 0.2 mm controls, P = 0.5) or between active/controlled disease. In the subset of participants with echocardiography (n = 32), left ventricular mass was higher by a mean of 38.2 g (95% confidence interval -80.9 to +4.6, P = 0.08). CONCLUSION: In summary, patients with acromegaly had independently and significantly increased aortic PWV as evidence of arterial stiffening but unaltered carotid IMT compared with controls, also influenced by age and systolic BP. Premature cardiovascular disease in patients with acromegaly is likely related to pressure-related arterial and left ventricular stiffening rather than atherosclerotic disease.

Corticosteroid-binding globulin regulates cortisol pharmacokinetics.

OBJECTIVE: Corticosteroid-binding globulin (CBG) is the principal carrier for cortisol in the circulation. Variations in CBG-binding capacity are predicted to alter total serum cortisol disposition, but free serum cortisol is believed to be unaffected. Unbound cortisol pharmacokinetics (PK) have not been studied in the context of CBG changes. We aimed to assess the regulation of cortisol PK by CBG. DESIGN AND SUBJECTS: Women on oestrogens [oral contraceptive pill, (OCP)], patients homozygous for a nonfunctioning CBG variant (CBG null) and healthy controls (HV) were studied before and after IV and oral administration of hydrocortisone 20 mg. MEASUREMENTS: PK parameters were studied for total serum cortisol (SerF), free serum cortisol (FreeF) and cortisone (FreeE), and salivary cortisol (SalF) and cortisone (SalE): area under the curve (AUC), clearance (CL), half-life and volume of distribution (V(d)). RESULTS: Following IV hydrocortisone, AUC and half-life of SerF were significantly higher in the OCP group and lower in the CBG null. SerF CL and V(d) were significantly lower in the OCP group and increased in the CBG null, compared to HV. PK parameters for FreeF and the salivary biomarkers were not different between the CBG null and HV, although OCP patients still had higher AUC compared to HV and prolonged half-life. These findings were confirmed following oral hydrocortisone, but concentration-time profiles were highly heterogeneous and SalF interpretation was problematic because of oral contamination. CONCLUSIONS: We have demonstrated that CBG has a distinct effect on cortisol PK. When CBG binding is disrupted, FreeF retains normal PK characteristics, although CBG null patients lack a CBG-bound pool of readily releasable cortisol. Women on oestrogens may have altered free serum cortisol kinetics and thus may be potentially overexposed to glucocorticoids.

Salivary cortisone is a potential biomarker for serum free cortisol.

CONTEXT: Salivary cortisol measurement is used as a practical surrogate for serum free cortisol. However, parotid tissue harbors 11ß-hydroxysteroid dehydrogenase (11ß-HSD2) activity converting cortisol to cortisone. OBJECTIVE: This study was designed to assess the impact of parotid 11ß-HSD2 activity on the measurement of salivary cortisol. PATIENTS, DESIGN, AND OUTCOME MEASURES: Study participants with changes in circulating corticosteroid-binding globulin (CBG) (±oral contraceptive, functionally CBG null) and controls were studied during adrenal stimulation by ACTH and postoral and iv hydrocortisone administration. Simultaneous serum and saliva samples were collected for the measurement of total serum cortisol (SerF) by immunoassay, and unbound cortisol and cortisone in serum (FreeF and FreeE) and saliva (SalF and SalE) by liquid chromatography-tandem mass spectrometry. RESULTS: ACTH stimulation increased SerF, FreeF, SalF, SalE, but not FreeE in all individuals. SerF significantly decreased after stopping oral contraceptive administration, but FreeF, SalF and SalE remained unchanged. In the hydrocortisone administration study, individual FreeF and SalE curves were nearly identical and SalE closely reflected FreeF in all participants, irrespective of CBG changes. The highest correlation in all (n = 537) matched serum-saliva samples was between SalE and FreeF (r = 0.95, P < 0.0001), and there was no evidence of 11ß-HSD2 saturation. CONCLUSION: Salivary cortisol is a useful surrogate for circulating free cortisol, but its concentration is determined both by serum free cortisol and parotid metabolism to cortisone. We have shown that salivary cortisone closely reflects free serum cortisol after adrenal stimulation and hydrocortisone administration and is unaffected by CBG changes. Salivary cortisone has potential as a useful surrogate for serum free cortisol in research and clinical assessment, and further research in states of chronic glucocorticoid excess is now needed.

Novel corticosteroid-binding globulin variant that lacks steroid binding activity.

BACKGROUND: Corticosteroid-binding globulin (CBG) is the principal carrier for glucocorticoids in the circulation and a regulator of their bioavailability. Inherited CBG deficiencies are rarely reported, and only three causative mutations in four families have been described. PATIENTS, METHODS, AND RESULTS: In a 26-yr-old female with hypotension, fatigue, and undetectable total serum cortisol at presentation, we have identified a novel homozygous c.776g>t transversion in exon 3 of the CBG (SERPINA6) gene. This results in a p.Gly237Val substitution that is predicted to influence the positioning of two ß-sheets that constitute part of the CBG steroid-binding site. Two siblings were also homozygous for the variant, whereas her mother and an unaffected sibling were heterozygous. No other symptomatic family members were identified apart from the proband. Individuals homozygous for the variant had serum CBG levels below the reference range when measured by RIA, but CBG was unmeasurable in cortisol-binding capacity assays. In the same individuals, we observed very low baseline and stimulated total serum cortisol levels but normal free serum and salivary cortisol and plasma ACTH. In a study of ultradian cortisol pulsatility, increased pulse frequency was only observed in the proband. CONCLUSION: We describe a novel CBG variant that lacks steroid binding activity. All mutant homozygotes have very low total serum cortisol, but normal free serum cortisol levels. The only biochemical feature to distinguish the symptomatic subject was increased cortisol pulsatility, and we suggest that this may influence glucocorticoid signaling and contribute to symptoms previously associated with CBG deficiency.

Successful use of weekly pegvisomant administration in patients with acromegaly.

CONTEXT: Clinical trials using 80 mg once weekly pegvisomant (pegV) in active acromegaly led to a 30% fall in serum IGF1. Subsequent studies demonstrated that daily administration of up to 40 mg/day achieved an IGF1 within reference range in 97% of patients. PegV has a half-life of >70 h suggesting weekly dosing may be possible but using higher doses than in the initial trials. OBJECTIVE: To determine the efficacy of weekly dosing of pegV. DESIGN: A two center, open-label prospective study in patients with acromegaly converted from a stable daily dose of pegV (median dose 15 mg daily (range 10-20 mg od), IGF1 normal for 3 months prior to inclusion) to twice-weekly (week 0-16) followed by once-weekly (week 16-32) administration. RESULTS: Seven patients (4M, age 57+/-7 years, 6/7 prior transsphenoidal surgery, 7/7 prior radiotherapy) were recruited. Six patients completed the twice-weekly and five patients both the twice-weekly and once-weekly administration. Headaches led to two patient withdrawals at 0+24 weeks. Mean pre-dose serum IGF1 levels remained stable with the different administration regimens (IGF1 baseline 145+/-39 ng/ml, twice-weekly 124+/-39 ng/ml and once-weekly 127+/-22 ng/ml) and all values were within age adjusted IGF1 reference range. PegV dose was reduced in two patients and five opted to continue weekly administration at trial termination. Safety and quality of life parameters remained stable. CONCLUSIONS: Twice and once-weekly administration of pegV is effective in controlling serum IGF1 levels in acromegaly and although not formally assessed, continuation of weekly dosing in five patients at study conclusion suggests patient preference for this regimen.

Pegvisomant improves insulin sensitivity and reduces overnight free fatty acid concentrations in patients with acromegaly.

INTRODUCTION: Acromegaly is complicated by an increased incidence of diabetes mellitus caused by impaired insulin sensitivity and reduced beta-cell function. Pegvisomant blocks activity at GH receptors, normalizing IGF-I in over 90% of patients and improving insulin sensitivity. The mechanisms for this increase in insulin sensitivity are not fully determined. We used stable isotope techniques to investigate the effects of pegvisomant on glucose and lipid metabolism in acromegaly. METHODS: Five patients (age, 43 yr +/- sd) with active acromegaly were studied on two occasions: before pegvisomant and after 4 wk of pegvisomant (20 mg daily sc). (2)H(5)-glycerol was infused overnight to measure overnight and early morning (basal) glycerol production rate (Ra). The next morning (2)H(2)-glucose was infused for 2 h before and throughout a hyperinsulinemic euglycemic (1.5 mU/kg x min insulin) clamp to measure basal glucose Ra and insulin-stimulated peripheral glucose disposal (Rd). RESULTS: Mean IGF-I was significantly reduced after pegvisomant treatment (mean, 539 +/- 176 vs. 198 +/- 168 microg/ml; P = 0.001). The insulin sensitivity of endogenous glucose production was significantly increased after pegvisomant [mean glucose Ra *insulin, 118.5 +/- 28 vs. 69.2 +/- 22 micromol/kg x min *(mU/liter); P = 0.04]. No differences in glucose Rd were seen after pegvisomant. All patients showed a reduction in glycerol Ra adjusted for insulin [mean, 18.12 +/- 1.75 vs. 14.4 +/- 4.75 micromol/kg x min *(mU/liter); P = 0.08] and overnight FFA concentrations (mean area under the curve, 278 +/- 84 vs. 203 +/- 71; P < 0.05) after pegvisomant. CONCLUSION: Short-term administration of pegvisomant leads to a reduction in overnight endogenous glucose production, and this may be related to reduced levels of FFA.

A subnormal peak cortisol response to stimulation testing does not predict a subnormal cortisol production rate.

INTRODUCTION: The decision to commence lifelong glucocorticoid replacement therapy is often based on a cortisol stimulation test. We investigated the relationship between the peak cortisol response to insulin-induced hypoglycemia and daily cortisol production rate (CPR) to ascertain whether provocative tests are accurate in indicating the need to initiate lifelong glucocorticoid replacement. PATIENTS AND METHODS: Ten patients (five male; mean age, 44 +/- 13 yr) with pituitary disease and with demonstrably suboptimal peak cortisol response (350-500 nmol/liter) to insulin-induced hypoglycemia, underwent CPR measurement by isotope dilution using gas chromatography-mass spectrometry and 24-h urinary free cortisol (UFC). RESULTS: The median baseline and peak cortisol attained with hypoglycemia were 284 (164-323) and 473.5 (366-494) nmol/liter, respectively. A strong positive correlation was seen between peak stimulated cortisol and CPR (adjusted for body surface area) (r = 0.75; P = 0.02), and in all patients CPR [4.6 (2.9-15.1) mg/d x m(2)] was within the reference range (2.1-12 mg/d x m(2)) or elevated (one patient). A wide range was found for 24-h UFC [116.5 (20.5-265.9) nmol/liter] in this group of patients, and this parameter lacked significant correlation with either serum cortisol concentration or CPR. CONCLUSION: This is the first study to demonstrate a significant correlation between CPR and peak cortisol values during hypoglycemic challenge. An inadequate cortisol response to hypoglycemia suggests the need for glucocorticoid cover at times of stress, but these data indicate that a suboptimal peak cortisol does not equate to a low CPR and should not be an automatic indication for lifelong glucocorticoid replacement therapy. UFC bears no relation to serum cortisol or CPR and is therefore unhelpful in assessment of such patients.

Long-term experience of pegvisomant therapy as a treatment for acromegaly.

AIMS: To evaluate the long-term efficacy and safety of pegvisomant as a treatment for acromegaly. DESIGN: Retrospective analysis of clinical and trial data from all patients treated with pegvisomant since 1997 at two centres with common protocols. RESULTS: Fifty-seven patients (age range 27-78 years) have been treated with pegvisomant since 1997 for up to 91 months (median 18 months). Before commencing pegvisomant, patients had an IGF-I above the upper limit of normal (ULN) of the age-related reference range (median 1.8 x ULN, range 1.2-4.1). Ninety-five per cent normalized IGF-I using a median dose of 15 mg daily (range 10 mg alternate day to 60 mg daily) with no influence of gender on dose requirement. Five patients had combination therapy with either somatostatin analogues (SSA) or cabergoline. Two patients initially controlled on 10 mg and 20 mg required dose increases (to 20 mg + 40 mg) over 24 months to reduce IGF-I. Twenty-seven patients stopped pegvisomant. Reasons included side-effects [abnormal liver function tests (LFTs)] and patient choice. Two patients developed elevated liver transaminases, which normalized on stopping pegvisomant. Patients had 6-12-monthly pituitary magnetic resonance imaging (MRI) scans. One patient had significant tumour size increase. CONCLUSION: This long-term experience in 57 patients indicates pegvisomant to be effective, safe and well-tolerated. Raised transaminases occurred within the first month of therapy in two patients, and tumour growth was seen in one patient (tumour was growing prior to pegvisomant). In two patients increasing doses of pegvisomant were required to keep IGF-I within the target range.

Use of a GH receptor antagonist (GHRA) to explore the relationship between GH and IGF-I in adults with severe GH deficiency (GHD).

OBJECTIVE: At diagnosis, approximately 50% of adults with severe GH deficiency (GHD) have an IGF-I within the reference range. It is unclear whether in such patients serum IGF-I levels are regulated by factors other than GH. DESIGN AND PATIENTS: We performed a double-blind, randomized, placebo-controlled, cross-over study to investigate the effect of the GH receptor antagonist - pegvisomant (20 mg daily for 14 days) on GH and IGF-I levels in three cohorts: patients with GHD and a normal IGF-I (NORMS); patients with GHD and a low IGF-I (LOWS) and healthy volunteers (CONS). RESULTS: Pegvisomant decreased IGF-I in CONS and NORMS [158.5 (101-206) vs. 103 (77-125) microg/l, P < 0.01; 124 (81-136) vs. 95 (51-113) microg/l, P < 0.01 respectively], but not in LOWS [31 (< 31-32) vs. 34.5 (< 31-38) microg/l], and this was associated with an increase in mean 24 h GH in CONS [0.49 (0.12-0.89) to 1.38 (0.22-2.45) microg/l (P = 0.03)] and in NORMS [69 (0-320)% from 0.1 (< 0.1-0.13) to 0.17 (0.11-0.42) microg/l (P = 0.03)], but not in the LOWS. The peak GH response to arginine was increased by pegvisomant in CONS and NORMS [6.1 (0.8-9) vs. 20.4 (13.1-28.8) microg/l, P = 0.03; 0.4 (0.1-0.5) vs. 0.5 (0.3-0.6) microg/l, respectively], but not in LOWS. CONCLUSIONS: These data indicate that patients with severe GHD with a normal IGF-I are able to increase GH secretion in response to a pegvisomant-induced fall in IGF-I, whereas those with low IGF-I levels are unable to increase GH secretion. Therefore circulating IGF-I appears to be GH-independent in GHD patients with a low IGF-I, but remains partially GH-dependent in GHD patients with a normal IGF-I.

Growth hormone excess and the development of growth hormone receptor antagonists.

In 1990, a single amino acid substitution in the growth hormone (GH) gene at position 119 was found to transform the consequent protein from an agonist to an antagonist at the growth hormone receptor (GHR). Further amino acid substitutions plus prolongation of the half-life of the protein by pegylation resulted in the first clinically effective GHR antagonist, pegvisomant. Following extensive clinical trials, this medication has emerged as the most efficacious therapy for treatment-resistant acromegaly. Subsequent advances in our understanding of GH-GHR interactions and downstream GH signalling pathways suggest that pegvisomant binds to preformed GHR dimers and prevents rotational changes within the receptor-GH complex necessary for intracellular signalling to occur. This article reviews the discovery of pegvisomant, from initial experimental data to successful licensing of the drug for treatment-resistant acromegaly, and discusses its other potential therapeutic uses in diseases with abnormalities in the GH-IGF-I axis.

Surgical debulking of pituitary macroadenomas causing acromegaly improves control by lanreotide.

BACKGROUND: Macroadenomas causing acromegaly are cured surgically in only around 50% of patients. Primary medical treatment with somatostatin analogues has been suggested to be a means of treating patients with a potentially poor surgical outcome. Previous retrospective studies have also suggested that surgical debulking of pituitary tumours causing acromegaly improves control by somatostatin analogues. No prospective study using lanreotide has been carried out thus far to assess whether this is the case. OBJECTIVE: We carried out a prospective study to assess whether surgical debulking of pituitary macroadenomas causing acromegaly improved the subsequent control of acromegaly by the somatostatin analogue lanreotide. PATIENTS AND METHODS: We treated 26 consecutive patients [10 males and 16 females--median age 53.5 years (range 22-70)] with macroadenoma causing acromegaly unselected for somatostatin response for 16 weeks with lanreotide, maximizing GH and IGF-I suppression, if necessary, by incremental dosing. Surgical resection was carried out and the patients were re-assessed off medical treatment at 16 weeks following surgery. Those with nadir GH > 2 mU/l in the oral glucose tolerance test (OGTT) and a mean GH in the GH day curve (GHDC) > 5 mU/l were subsequently restarted on lanreotide and the responses were assessed at the same time points as during the preoperative lanreotide treatment. RESULTS: GH values fell on lanreotide treatment and prior to surgery they were considered 'safe' (mean GH in GHDC < 5 mU/l) in eight patients (30.7%). After surgery, they were 'safe' in 18 patients (69.2%). The figures for normal IGF-I were 11 (42.3%) before surgery and 23 (88.5%) after surgery. After surgery, six patients had nadir GH > 2 mU/l in the OGTT and 'unsafe' GH levels (mean GH in GHDC > 5 mU/l); on re-exposure to lanreotide, GH levels fell in all patients and at the end of 16 weeks postsurgery, they were 'safe' in three of them (50%) (P < 0.05). Pituitary tumour volume was also assessed prospectively, preoperatively on lanreotide and showed a mean fall of 33.1%. Eighty-three percent of patients had > 20% shrinkage. CONCLUSIONS: In this first prospective study using lanreotide, surgical debulking of pituitary tumours causing acromegaly improved subsequent postoperative control by the somatostatin analogue lanreotide. Surgery should, therefore, be considered in patients with macroadenoma causing acromegaly, even if there is little prospect of surgical cure. Lanreotide causes significant pituitary tumour shrinkage in the majority of patients.

Wide variation in surgical outcomes for acromegaly in the UK.

OBJECTIVE: Unsuccessful surgery for acromegaly has major consequences for the patient as well as financial consequences for the National Health Service (NHS). Surgical expertise affects the outcome. We have used the UK National Acromegaly Register to assess surgical outcomes in different centres to investigate whether these match the previously published case series. DESIGN: Retrospective and prospective observational study by analysis of anonymized national computer register records derived from individual clinical case records from 22 UK endocrine units and their associated pituitary surgical services. PATIENTS: Cases of acromegaly, presenting in 1970-2004, with levels of GH or IGF-1 (785 and 430 cases, respectively) recorded prior to transsphenoidal adenomectomy and in the 12 months postsurgery, before any subsequent pituitary surgery or radiotherapy. GH-lowering pharmacological therapy was permitted only if suspended for biochemical testing. MEASUREMENTS: Percentage of cases with 'safe' mean postoperative GH levels (< 5 mU/l) and/or IGF-1 in the age- and sex-adjusted normal range. RESULTS: 'Safe' GH, normal IGF-1, or both was achieved for 26%, 29% and 20% of extrasellar macroadenomas (> 1 cm), respectively, 39%, 39% and 29% of intrasellar macroadenomas, 56%, 51% and 37% of microadenomas (< 1 cm) and 39%, 39% and 28% of cases overall. In centres contributing more than 10 patients' data, rates of safe GH levels ranged from 20% to 68% and IGF-1 from 19% to 55%. Success rates in attaining safe postsurgical levels of GH improved only slightly in the UK between 1974 and 1999 but markedly thereafter. CONCLUSIONS: Surgical outcomes for acromegaly in UK centres vary widely and historically have not, except in a few centres, matched those of large published series, which mostly have a success rate around 60%. Results have, however, improved substantially since 2000 and in the most successful units match those of the best published series. Experience is an important determinant of surgical success in acromegaly and the very recent improvement in surgical results in the UK coincides with a trend to concentrate pituitary surgery in the hands of a smaller number of specialists. Therefore, patients should be offered surgery by a dedicated pituitary surgeon with a caseload sufficient to offer the prospect of safe postsurgical GH and IGF-1 levels for the majority of cases.

Variation in GH and IGF-I assays limits the applicability of international consensus criteria to local practice.

BACKGROUND: There is increasing reliance on consensus criteria for decision making. Recent criteria state that acromegaly is excluded by a nadir GH during an oral glucose tolerance test (OGTT) of < 1 microg/l and a normal level of IGF-I. OBJECTIVE: To study GH and IGF-I assay performance close to cut-off values for active acromegaly. DESIGN AND METHODS: Two serum samples known to give borderline results were sent to all centres participating in the UK National External Quality Assessment Service (NEQAS). Sample A was assigned to be a nadir during an OGTT and sent for GH assessment to 104 centres. Sample B, with a clinical scenario, was sent to 23 centres that measure IGF-I, and these centres were asked to measure IGF-I, interpret the result and provide the source of their reference ranges (RRs). RESULTS: For sample A, the median GH was 2.6 mU/l (range 1.04-3.5 mU/l). Applying a conversion factor (CF) of 2.0 (1 microg/l = 2 mU/l), the most negatively biased method classified 10% of the values consistent with acromegaly, while the most positively biased method classified all values as consistent with the diagnosis. Applying a CF of 3.0 (1 microg/l = 3 mU/l), only 11% of results were consistent with acromegaly. For sample B, the median IGF-I was 50.8 nmol/l (range 24.3-60.9 nmol/l). All centres used age-related RRs. There was a 50% variation in the upper limit of the RRs between centres. Overall, 30% of the IGF-I results were against the diagnosis. There was little agreement in the RRs quoted by centres using the same method. CONCLUSION: Variability in assay performance, coupled with use of inappropriate CFs and RRs, undermines the applicability of international consensus criteria to local practice.