Review of current and emerging treatment options in acromegaly

In almost every patient, acromegaly is caused by a growth hormone secreting pituitary adenoma. Clinical features are the result of excessive growth hormone secretion and the consecutive excess in insulin-like growth factor I levels. This results in somatic overgrowth and metabolic disturbances with a higher morbidity and mortality than in the general population. With optimal disease management, mortality can be reduced to that seen in the general population. The current treatment of acromegaly is based on a combination of surgery, radiotherapy and medical therapy. This review provides an overview of the current and upcoming therapies with a focus on medical therapy.

Pituitary dysfunction after aneurysmal subarachnoid haemorrhage: course and clinical predictors—the HIPS study

OBJECTIVE

We describe the occurrence and course of anterior pituitary dysfunction (PD) after aneurysmal subarachnoid haemorrhage (SAH), and identify clinical determinants for PD in patients with recent SAH.

METHODS

We prospectively collected demographic and clinical parameters of consecutive survivors of SAH and measured fasting state endocrine function at baseline, 6 and 14 months. We included dynamic tests for growth-hormone function. We used logistic regression analysis to compare demographic and clinical characteristics of patients with SAH with and without PD.

RESULTS

84 patients with a mean age of 55.8 (±11.9) were included. Thirty-three patients (39%) had PD in one or more axes at baseline, 22 (26%) after 6 months and 6 (7%) after 14 months. Gonadotropin deficiency in 29 (34%) patients and growth hormone deficiency (GHD) in 26 (31%) patients were the most common deficiencies. PD persisted until 14 months in 6 (8%) patients: GHD in 5 (6%) patients and gonadotropin deficiency in 4 (5%). Occurrence of a SAH-related complication was associated with PD at baseline (OR 2.6, CI 2.2 to 3.0). Hydrocephalus was an independent predictor of PD 6 months after SAH (OR 3.3 CI 2.7 to 3.8). PD was associated with a lower score on health-related quality of life at baseline (p=0.06), but not at 6 and 14 months.

CONCLUSIONS

Almost 40% of SAH survivors have PD. In a small but substantial proportion of patients GHD or gonadotropin deficiency persists over time. Hydrocephalus is independently associated with PD 6 months after SAH.

TRIAL REGISTRATION NUMBER

NTR 2085.

Pregnancy in acromegaly patients treated with pegvisomant

To summarize all available data on pregnancy outcome of acromegaly patients exposed to the growth hormone receptor antagonist pegvisomant (PEGV) during pregnancy as present in the Pfizer's Global Safety Database. Pfizer's Global Safety Database contains adverse event data obtained from the following sources: spontaneous reports, health authorities, Pfizer-sponsored post-marketing surveillance program (ACROSTUDY), customer engagement programs, and clinical studies, reported regardless of outcome. The safety database was searched up to 10th March 2014. From the 35 pregnancy cases, 27 involved maternal [mean age (range) 33.3 years (23-41) and 8 paternal (33.7 years (32-38)] PEGV exposure. Two female patients were reported with two pregnancy cases each. Fetal outcome was normal in 14 (4 paternal) of the 18 reported as live birth, while 4 cases (1 paternal) did not specify the birth outcome. At conception, PEGV mean dose (range) was 15.3 mg/d (4.3-30). In 3 cases of maternal exposure of the 18 cases reporting live birth, PEGV was continued throughout the pregnancy in a dose of 12.1 mg/d (10-15). In 5 cases (all maternal) an elective termination of the pregnancy was performed with no reported fetal abnormalities, 2 cases (maternal) reported a non-PEGV-related spontaneous abortion and in 1 maternal case an ectopic pregnancy occurred. In 9 cases (3 paternal), the fetal outcome was not reported. Three women reported gestational diabetes; one woman continued PEGV treatment during pregnancy. Although the number of reported pregnancies with exposure to PEGV is very small, the presented data reflect the largest series of data available to date and do not suggest adverse consequences of PEGV on pregnancy outcome. Nevertheless, it should be stressed that PEGV should not be used during pregnancy unless absolutely necessary.

Changes in circulating IGF1 receptor stimulating activity do not parallel changes in total IGF1 during GH treatment of GH-deficient adults

CONTEXT

Previously we demonstrated that IGF1 receptor stimulating activity (IGF1RSA) offers advantages in diagnostic evaluation of adult GH deficiency (GHD). It is unknown whether IGF1RSA can be used to monitor GH therapy.

OBJECTIVE

To investigate the value of circulating IGF1RSA for monitoring GH therapy.

DESIGN/METHODS

106 patients (54 m; 52 f) diagnosed with GHD were included; 22 were GH-naïve, 84 were already on GH treatment and discontinued therapy 4 weeks before baseline values were established. IGF1RSA was determined by the IGF1R kinase receptor activating assay, total IGF1 by immunoassay (Immulite). GH doses were titrated to achieve total IGF1 levels within the normal range.

RESULTS

After 12 months, total IGF1 and IGF1RSA increased significantly (total IGF1 from 8.1 (95% CI 7.3-8.9) to 14.9 (95% CI 13.5-16.4) nmol/l and IGF1RSA from 115 (95% CI 104-127) to 181 (95% CI 162-202) pmol/l). After 12 months, total IGF1 normalized in 81% of patients, IGF1RSA in 51% and remained below normal in more than 40% of patients in whom total IGF1 had normalized.

CONCLUSIONS

During 12 months of GH treatment, changes in IGF1RSA did not parallel changes in total IGF1. Despite normalization of total IGF1, IGF1RSA remained subnormal in a considerable proportion of patients. At present our results have no short-term consequences for GH therapy of GHD patients. However, based on our findings we propose future studies to examine whether titrating GH dose against IGF1RSA results in a better clinical outcome than titrating against total IGF1.

Tumor Recurrence or Regrowth in Adults With Nonfunctioning Pituitary Adenomas Using GH Replacement Therapy

CONTEXT

GH replacement therapy (GH-RT) is a widely accepted treatment in GH-deficient adults with nonfunctioning pituitary adenoma (NFPAs). However, some concerns have been raised about the safety of GH-RT because of its potentially stimulating effect on tumor growth.

OBJECTIVE

The aim of this study was to evaluate tumor progression in NFPA patients using GH-RT.

DESIGN, SETTING, AND PATIENTS

From the Dutch National Registry of Growth Hormone Treatment in Adults, a nationwide surveillance study in severely GH-deficient adults (1998-2009), all NFPA patients with ≥ 30 days of GH-RT were selected (n = 783). Data were retrospectively collected from the start of GH-RT in adulthood (baseline).

MAIN OUTCOME MEASURE

Tumor progression, including tumor recurrence after complete remission at baseline and regrowth of residual tumor.

RESULTS

Tumor progression developed in 12.1% of the patients after a median (range) time of 2.2 (0.1-14.9) years. Prior radiotherapy decreased tumor progression risk compared to no radiotherapy (hazard ratio = 0.16; 95% confidence interval, 0.09-0.26). Analysis in 577 patients with available baseline imaging data showed that residual tumor at baseline increased tumor progression risk compared to no residual tumor (hazard ratio = 4.5; 95% confidence interval, 2.4-8.2).

CONCLUSIONS

The findings in this large study were in line with those reported in literature and provide further evidence that GH-RT does not appear to increase tumor progression risk in NFPA patients. Although only long-term randomized controlled trials will be able to draw firm conclusions, our data support the current view that GH-RT is safe in NFPA patients.

Ghrelin

BACKGROUND

The gastrointestinal peptide hormone ghrelin was discovered in 1999 as the endogenous ligand of the growth hormone secretagogue receptor. Increasing evidence supports more complicated and nuanced roles for the hormone, which go beyond the regulation of systemic energy metabolism.

SCOPE OF REVIEW

In this review, we discuss the diverse biological functions of ghrelin, the regulation of its secretion, and address questions that still remain 15 years after its discovery.

MAJOR CONCLUSIONS

In recent years, ghrelin has been found to have a plethora of central and peripheral actions in distinct areas including learning and memory, gut motility and gastric acid secretion, sleep/wake rhythm, reward seeking behavior, taste sensation and glucose metabolism.

Cerebrovascular events, secondary intracranial tumors, and mortality after radiotherapy for nonfunctioning pituitary adenomas: a subanalysis from the Dutch National Registry of Growth Hormone Treatment in Adults

CONTEXT

Radiotherapy is frequently administered as adjuvant treatment in patients with clinically nonfunctioning pituitary adenomas (NFPAs). However, concerns have been raised about potential long-term side effects, including cerebrovascular events (CVEs) and secondary intracranial tumors.

OBJECTIVE

The aim of this study was to analyze the risk of CVEs, secondary intracranial tumors, and mortality in irradiated (IRR) NFPA patients, compared with NFPA patients who were not irradiated (non-IRR).

DESIGN, SETTING, AND PATIENTS

The study cohort included 806 patients with a NFPA from the Dutch National Registry of Growth Hormone Treatment in Adults, a nationwide long-term surveillance study in severe GH-deficient adult patients. IRR patients (n = 456) were compared with non-IRR patients (n = 350).

MAIN OUTCOME MEASURES

CVEs, secondary intracranial tumors, and mortality were measured.

RESULTS

Sixty-nine subjects developed a CVE. In men, but not in women, the incidence of a CVE was significantly higher in IRR patients than in non-IRR patients (hazard ratio 2.99, 95% confidence interval 1.31-6.79). A secondary intracranial tumor developed in five IRR patients and two non-IRR patients. After adjustment for age, radiotherapy was not associated with mortality.

CONCLUSIONS

The incidence of secondary intracranial tumors and mortality did not differ between IRR and non-IRR patients. However, a CVE was found significantly more frequently in IRR men but not in women. Further research into the long-term effects of cranial radiotherapy seems mandatory. The potential risks of radiotherapy have to be taken into account when radiotherapy is considered in NFPA patients, and long-term follow-up is recommended.

The introduction of the IDS-iSYS total IGF-1 assay may have far-reaching consequences for diagnosis and treatment of GH deficiency

CONTEXT

IGF-1 measurements are used for screening and monitoring GH deficiency (GHD) and acromegaly.

OBJECTIVE

Our objective was to study whether the introduction of the IDS-iSYS IGF-1 assay would lead to different clinical interpretations in GHD and acromegaly.

DESIGN

In 106 GHD subjects and in 15 acromegalic subjects visiting our university hospital, total IGF-1 levels were measured before and during therapy by using the Immulite (IM) assay and IDS-iSYS (ID) assay. Z-scores were calculated by using assay-specific age-specific normative range values. All treatment decisions were based upon results obtained by the IM assay.

RESULTS

In GHD subjects, absolute IGF-1 concentrations differed significantly between both IGF-1 assays before treatment (P < .001) but not during GH treatment (P = .32), and mean Z-scores for IGF-1 differed significantly before starting (IM, -2.23, vs ID, -1.43; P < .001) and during GH treatment (IM, -0.60, vs ID, +0.21; P < .001). In acromegalic subjects, absolute IGF-1 concentrations did not differ between both IGF-1 assays before treatment (P = .18) but were significantly different during treatment (P = 0.009), and mean Z-scores for IGF-1 were not different before starting (IM, 10.93, vs ID, 10.78; P = .41) or during treatment (IM, 3.60, vs ID, 3.18; P = .23).

CONCLUSIONS

In GHD subjects, mean IGF-1 Z-scores significantly differed when measured by the IM assay compared with the ID assay irrespective of treatment. In contrast, in acromegaly, mean IGF-1 Z-scores did not differ significantly between both assays. Our study suggests that replacement of the IM assay by the ID assay may have far-reaching consequences for the clinical diagnosis and treatment of GHD.

Long-term efficacy and safety of pegvisomant in combination with long-acting somatostatin analogs in acromegaly

BACKGROUND

Treatment for acromegaly patients with long-acting somatotropin release-inhibiting factor (LA-SRIF) often does not result in complete normalization of IGF-1. Addition of pegvisomant (PEGV), a GH receptor antagonist, could improve this; however, the literature has not described long-term follow-up.

OBJECTIVE

To assess long-term efficacy and safety of this combined treatment in the largest current single-center cohort of patients, from 2004-2013.

DESIGN

Acromegaly patients were treated for at least 6 months with a high-dose LA-SRIF. To patients with persistently elevated IGF-1 levels (>1.2 × upper limit of normal) or poor quality of life, PEGV was added as one weekly injection.

RESULTS

The patients (n = 141) were treated with PEGV and LA-SRIFs for a median period of 4.9 years (range, 0.5-9.2). Efficacy, defined as the lowest measured IGF-1 level during treatment, was 97.0%. The median PEGV dose to achieve this efficacy was 80 mg weekly (interquartile range, 60-120 mg). Combination treatment-related adverse events were recorded in 26 subjects (18.4%). Pituitary tumor size increase was observed in one patient. Injection-site reactions were observed in four subjects. In 19 patients (13.5%), transiently elevated liver transaminases of more than three times the upper limit of normal were observed, of which 83% occurred within the first year of combination treatment. Eight patients died, at a mean age of 71 years; none of them were considered treatment-related.

CONCLUSIONS

The combination treatment with LA-SRIFs and PEGV was effective in 97% of the patients, it appears to be a safe medical treatment and it reduces the required dose of PEGV.

Development of potent selective competitive-antagonists of the melanocortin type 2 receptor

Cushing's disease, a hypercortisolemic state induced by an ACTH overexpressing pituitary adenoma, causes increased morbidity and mortality. Selective antagonism of the melanocortin type 2 receptor (MC2R) may be a novel treatment modality. Five structurally related peptides with modified HFRW sites but intact putative MC2R binding sites were tested for antagonistic activity at MC1R, MC2R/MRAP, MC3R, MC4R and MC5R. Two of these peptides (GPS1573 and GPS1574) dose-dependently antagonized ACTH-stimulated MC2R activity (IC50s of 66±23 nM and 260±1 nM, respectively). GPS1573 and 1574 suppressed the Rmax but not EC50 of ACTH on MC2R, indicating non-competitive antagonism. These peptides did not antagonize α-MSH stimulation of MC1R and antagonized MC3, 4 and 5R at markedly lower potency. GP1573 and GPS1574 antagonize MC4R with IC50s of 950 nM and 3.7 μM, respectively. In conclusion, two peptide antagonists were developed with selectivity for MC2R, forming a platform for development of a medical treatment for Cushing's disease.

Differentiating between Cushing's disease and pseudo-Cushing's syndrome: comparison of four tests

OBJECTIVE

To evaluate the diagnostic performance of four different tests in order to differentiate between Cushing's disease (CD) and pseudo-Cushing's syndrome (PCS).

METHODS

In this prospective study, a total of 73 patients with clinical features of hypercortisolism and insufficient suppression of serum cortisol after 1 mg overnight dexamethasone and/or an elevated excretion of cortisol in 24-h urine samples were included. The circadian rhythm of serum cortisol levels as well as midnight serum cortisol (MserC) levels were assessed in all 73 patients. Late-night salivary cortisol (LNSC) concentrations were obtained in 44 patients. The dexamethasone-CRH (Dex-CRH) test was performed in 54 patients.

RESULTS

FIFTY-THREE PATIENTS WERE DIAGNOSED WITH CD AND SUBSEQUENTLY TREATED. TWENTY PATIENTS WERE CLASSIFIED AS HAVING PSC. SERUM CORTISOL CIRCADIAN RHYTHM: the diurnal rhythmicity of cortisol secretion was retained in PCS. A cortisol midnight:morning ratio of >0.67 is highly suggestive of CD (positive predictive value (PPV) 100% and negative predictive value (NPV) 73%). MserC concentration >243 nmol/l has a PPV of 98% in predicting true CD (NPV 95%). LNSC level >9.3 nmol/l predicted CD in 94% of patients (NPV 100%). Dex-CRH test: after 2 days of dexamethasone suppression, a CRH-stimulated cortisol level >87 nmol/l (T=15 min) resulted in a PPV of 100% and an NPV of 90%.

CONCLUSION

The Dex-CRH test as well as a single measurement of cortisol in serum or saliva at late (mid-) night demonstrated high diagnostic accuracy in differentiating PCS from true CD.

Pasireotide versus octreotide in acromegaly: a head-to-head superiority study

CONTEXT

Biochemical control reduces morbidity and increases life expectancy in patients with acromegaly. With current medical therapies, including the gold standard octreotide long-acting-release (LAR), many patients do not achieve biochemical control.

OBJECTIVE

Our objective was to demonstrate the superiority of pasireotide LAR over octreotide LAR in medically naive patients with acromegaly.

DESIGN AND SETTING

We conducted a prospective, randomized, double-blind study at 84 sites in 27 countries.

PATIENTS

A total of 358 patients with medically naive acromegaly (GH >5 μg/L or GH nadir ≥1 μg/L after an oral glucose tolerance test (OGTT) and IGF-1 above the upper limit of normal) were enrolled. Patients either had previous pituitary surgery but no medical treatment or were de novo with a visible pituitary adenoma on magnetic resonance imaging.

INTERVENTIONS

Patients received pasireotide LAR 40 mg/28 days (n = 176) or octreotide LAR 20 mg/28 days (n = 182) for 12 months. At months 3 and 7, titration to pasireotide LAR 60 mg or octreotide LAR 30 mg was permitted, but not mandatory, if GH ≥2.5μg/L and/or IGF-1 was above the upper limit of normal.

MAIN OUTCOME MEASURE

The main outcome measure was the proportion of patients in each treatment arm with biochemical control (GH <2.5 μg/L and normal IGF-1) at month 12.

RESULTS

Biochemical control was achieved by significantly more pasireotide LAR patients than octreotide LAR patients (31.3% vs 19.2%; P = .007; 35.8% vs 20.9% when including patients with IGF-1 below the lower normal limit). In pasireotide LAR and octreotide LAR patients, respectively, 38.6% and 23.6% (P = .002) achieved normal IGF-1, and 48.3% and 51.6% achieved GH <2.5 μg/L. 31.0% of pasireotide LAR and 22.2% of octreotide LAR patients who did not achieve biochemical control did not receive the recommended dose increase. Hyperglycemia-related adverse events were more common with pasireotide LAR (57.3% vs 21.7%).

CONCLUSIONS

Pasireotide LAR demonstrated superior efficacy over octreotide LAR and is a viable new treatment option for acromegaly.

In active acromegaly, IGF1 bioactivity is related to soluble Klotho levels and quality of life

The value of measuring IGF1 bioactivity in active acromegaly is unknown. Soluble Klotho (S-Klotho) level is elevated in active acromegaly and it has been suggested that S-Klotho can inhibit activation of the IGF1 receptor (IGF1R). A cross-sectional study was carried out in 15 patients with active acromegaly based on clinical presentation, unsuppressed GH during an oral glucose tolerance test, and elevated total IGF1 levels (>+2 s.d.). Total IGF1 was measured by immunoassay, IGF1 bioactivity by the IGF1R kinase receptor activation assay and S-Klotho by an ELISA. Quality of Life (QoL) was assessed by Acromegaly QoL (AcroQoL) Questionnaire and Short-Form-36 Health Survey Questionnaire (SF-36). Out of 15 patients, nine had IGF1 bioactivity values within the reference range. S-Klotho was higher in active acromegaly compared with controls. Age-adjusted S-Klotho was significantly related to IGF1 bioactivity (r=0.75, P=0.002) and to total IGF1 (r=0.62, P=0.02). IGF1 bioactivity and total IGF1 were inversely related to the physical component summary of the SF-36 (r=-0.78, P=0.002 vs r=-0.60, P=0.03). Moreover, IGF1 bioactivity, but not total IGF1, was significantly inversely related to the physical dimension of the AcroQoL Questionnaire (r=-0.60, P=0.02 vs r=-0.37, P=0.19). In contrast to total IGF1, IGF1 bioactivity was within the reference range in a considerable number of subjects with active acromegaly. Elevated S-Klotho levels may have reduced IGF1 bioactivity. Moreover, IGF1 bioactivity was more strongly related to physical measures of QoL than total IGF1, suggesting that IGF1 bioactivity may better reflect physical limitations perceived in active acromegaly.

Cortisol diurnal rhythm and quality of life after successful medical treatment of Cushing's disease

Cushing's disease (CD) is associated with severely impaired quality of life (QoL). Moreover, the physiological cortisol diurnal rhythm (CDR) is disturbed in CD. QoL can improve after successful surgery, the primary treatment for CD. We evaluated the effects of medical treatment on QoL and CDR. In 17 patients, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline and the adrenal-blocking agent ketoconazole. After 80 days, 15/17 (88%) patients had reached normal urinary free cortisol excretion (UFC). Subsequently, patients continued medical therapy or underwent surgery. UFC, plasma and salivary CDR and QoL-related parameters (assessed using 5 questionnaires: Nottingham Health Profile, Hospital Anxiety and Depression Scale, Multidimensional Fatigue Index-20, RAND-36, CushingQoL) were measured. At baseline, 5/17 patients had preserved CDR. In 6/12 patients with disturbed baseline CDR, recovery was observed, but without any correlation with QoL. QoL was significantly impaired according to 18/20 subscales in CD patients compared to literature-derived controls. According to the RAND-36 questionnaire, patients reported more pain at day 80 (p < 0.05), which might reflect steroid-withdrawal. Generally, QoL did not improve or deteriorate after 80 days. CushingQoL scores seemed to improve after 1 year of remission in three patients that continued medical therapy (p = 0.11). CDR can recover during successful pituitary- and adrenal-targeted medical therapy. Patients with CD have impaired QoL compared to controls. Despite the occurrence of side-effects, QoL does not deteriorate after short-term biochemical remission induced by medical therapy, but might improve after sustained control of hypercortisolism.

Final height and IGF1 in adult survivors of Wilms tumour

OBJECTIVE

One-sided nephrectomy is followed by increased levels of IGF1, associated with linear growth during childhood. The aim was to evaluate final height and IGF1 levels in nephrectomized Wilms tumour survivors when compared with healthy Dutch references and survivors of other cancer types.

DESIGN

Cross-sectional retrospective study.

METHODS

Data of 575 adult childhood cancer survivors were analysed. median follow-up time was 17.8 (range 5.048.8) years. Analysis of (co)variance was performed to evaluate differences between subgroups: nephrectomized Wilms survivors treated with or without abdominal irradiation (n=41 and n=36) and survivors of other cancer types treated with or without irradiation involving the cranium, abdomen or total body (n=149 and n=349). Main outcome measures were IGF1 and height, expressed as SDS.

RESULTS

After adjustment for age at diagnosis, former corticosteroid treatment and renal impairment, height SDS in non-irradiated nephrectomized Wilms survivors was significantly higher than that in non-irradiated survivors of other cancer types (estimated mean SDS -0.09 vs -0.49, P=0.044), abdominal irradiated survivors (SDS -0.70, P=0.015) and other irradiated survivors (SDS -1.47, P<0.001). Non-irradiated nephrectomized Wilms tumour survivors had significantly higher IGF1 SDS than other irradiated survivors (estimated mean SDS -0.05 vs -1.36, P<0.001 and 0.11 vs 1.37, P<0.001), while there was no significant difference with the other two subgroups.

CONCLUSIONS

Adult survivors of Wilms tumour showed better attainment of final height and relatively higher IGF1 levels than those of other cancer types who had significantly shorter stature and lower IGF1 levels than Dutch references.

Diagnostic value of a ghrelin test for the diagnosis of GH deficiency after subarachnoid hemorrhage

OBJECTIVE

To determine the diagnostic value of a ghrelin test in the diagnosis of GH deficiency (GHD) shortly after aneurysmal subarachnoid hemorrhage (SAH).

DESIGN

Prospective single-center observational cohort study.

METHODS

A ghrelin test was assessed after the acute phase of SAH and a GH-releasing hormone (GHRH)-arginine test 6 months post SAH. Primary outcome was the diagnostic value of a ghrelin test compared with the GHRH-arginine test in the diagnosis of GHD. The secondary outcome was to assess the safety of the ghrelin test, including patients' comfort, adverse events, and idiosyncratic reactions.

RESULTS

Forty-three survivors of SAH were included (15 males, 35%, mean age 56. 6 ± 11.7). Six out of 43 (14%) SAH survivors were diagnosed with GHD by GHRH-arginine test. In GHD subjects, median GH peak during ghrelin test was significantly lower than that of non-GHD subjects (5.4 vs 16.6, P=0.002). Receiver operating characteristics analysis showed an area under the curve of 0.869. A cutoff limit of a GH peak of 15 μg/l corresponded with a sensitivity of 100% and a false-positive rate of 40%. No adverse events or idiosyncratic reactions were observed in subjects undergoing a ghrelin test, except for one subject who reported flushing shortly after ghrelin infusion.

CONCLUSION

Owing to its convenience, validity, and safety, the ghrelin test might be a valuable GH provocative test, especially in the early phase of SAH.

Desacyl ghrelin is influenced by changes in insulin concentration during an insulin tolerance test

OBJECTIVE

Ghrelin, a gut-brain peptide, regulates energy homeostasis and glucose metabolism and is present in acylated and nonacylated form in the circulation. Although desacyl ghrelin (DAG), the predominant form of ghrelin, is associated with insulin sensitivity and improved metabolic state, not much is known about its direct regulation by insulin. We aimed to assess changes in DAG in response to the rapid increase in insulin concentration during an insulin tolerance test (ITT) in normal weight and obese subjects.

DESIGN

We performed an observational single center study. An ITT was assessed in eight subjects (four males), median age of 29.9 years (range 19.6-42.0). DAG concentrations were measured at 20, 40, 60 and 90 min after insulin infusion. Homeostatic Model Assessment (HOMA) was calculated from fasting insulin and glucose. Body mass index (BMI) and waist circumference were assessed.

RESULTS

Three subjects were obese (BMI ≥ 30 kg/m(2)), one subject was overweight (BMI = 25-30 kg/m(2)) and four subjects had normal weight (BMI = 18.5-25 kg/m(2)). Median DAG decreased after insulin infusion (90 pg/mL, p = 0.028), especially in normal weight subjects. Baseline DAG was lower in subjects with higher BMI (ρ = -0.76, p = 0.028) and higher fasting insulin (ρ = -0.76, p = 0.030). DAG changes correlated with fasting insulin levels (ρ = -0.85, p = 0.007), HOMA (ρ = -0.86, p = 0.007), BMI (ρ = -0.83, p = 0.010) and waist circumference (ρ = -0.93, p < 0.001).

CONCLUSION

DAG levels rapidly decreased in response to insulin administration in normal subjects, but not in insulin-resistant obese who are in a state of relative DAG deficiency.

Decreased ovarian function is associated with obesity in very long-term female survivors of childhood cancer

OBJECTIVE

Obesity and gonadal dysfunction are known major side effects of treatment in adult childhood cancer survivors (CCS). In the general population, obesity has a negative influence on female fertility. We aimed to evaluate whether obesity and serum insulin are associated with decreased ovarian reserve markers in CCS.

DESIGN

Retrospective single-center cohort study.

METHODS

Data of 191 female survivors of childhood cancer were analyzed. Median follow-up time was 18.8 (2.348.8) years. Outcome measures were serum anti-Müllerian hormone (AMH) and total follicle count (FC). Potential risk factors were: BMI; body composition measures, determined by dual-energy X-ray absorptiometry (total fat percentage, lean body mass, and visceral fat percentage); and fasting insulin.

RESULTS

Lower serum AMH was found in obese subjects (β (%) -49, P=0.007) and in subjects with fasting insulin in the highest tertile (β (%) -43, P=0.039). Total fat percentage tends to be associated with serum AMH (β (%) -2.1, P=0.06). Survivors in the highest tertile of insulin had significantly lower FC than survivors in the lowest tertile (β -6.3, P=0.013). BMI and other measures of body composition were not associated with FC. Correlation between serum AMH and antral follicle count (AFC) was ρ=0.32 (P=0.08).

CONCLUSIONS

Obesity and insulin resistance are associated with gonadal damage, as reflected by decreased AMH and reduced FC in adult survivors of childhood cancer. In contrast to its highly predictive value for AFC in the healthy female population, serum AMH does not seem to correlate as well with AFC in CCS.

Metabolic effects of overnight continuous infusion of unacylated ghrelin in humans

OBJECTIVE

To clarify the metabolic effects of an overnight i.v. infusion of unacylated ghrelin (UAG) in humans. UAG exerts relevant metabolic actions, likely mediated by a still unknown ghrelin receptor subtype, including effects on β-cell viability and function, insulin secretion and sensitivity, and glucose and lipid metabolism.

DESIGN

We studied the effects of a 16-h infusion (from 2100 to 1300  h) of UAG (1.0  μg/kg per h) or saline in eight normal subjects (age (mean±s.e.m.), 29.6±2.4 years; body mass index (BMI), 22.4±1.7  kg/m(2)), who were served, at 2100 and 0800  h respectively, with isocaloric balanced dinner and breakfast. Glucose, insulin, and free fatty acid (FFA) levels were measured every 20  min.

RESULTS

In comparison with saline, UAG induced significant (P<0.05) changes in glucose, insulin, and FFA profiles. UAG infusion decreased glucose area under the curve (AUC) values by 10% (UAG(0 - 960  min): 79.0±1.7×10(3)  mg/dl per min vs saline(0- 960  min): 87.5±3.8×10(3)  mg/dl per min) and the AUC at night by 14% (UAG(180)(-)(660  min): 28.4±0.5×10(3)  mg/dl per min vs saline(180 - 660  min): 33.2±1.1×10(3)  mg/dl per min). The overall insulin AUC was not significantly modified by UAG infusion; however, insulin AUC observed after meals was significantly increased under the exposure to UAG with respect to saline at either dinner or breakfast. The FFA AUC values were decreased by 52% under the exposure to UAG in comparison with saline (UAG(0 - 960  min): 0.3±0.02×10(3)  mEq/l per min vs saline(0 - 960  min): 0.6±0.05×10(3)  mEq/l per min).

CONCLUSIONS

Exposure to the i.v. administration of UAG improves glucose metabolism and inhibits lipolysis in healthy volunteers. Thus, in contrast to the diabetogenic action of AG, UAG displays hypoglycemic properties.

Long-term safety of pegvisomant in patients with acromegaly: comprehensive review of 1288 subjects in ACROSTUDY

CONTEXT

Pegvisomant is a GH receptor antagonist. The ACROSTUDY is a global safety surveillance study of long-term treatment of acromegaly with pegvisomant.

OBJECTIVE

The objective of the study was to monitor long-term safety and treatment outcomes.

DESIGN

ACROSTUDY is open to all patients with acromegaly who are treated with pegvisomant. We report an interim analysis of data captured from 1288 subjects enrolled before a database freeze of December 31, 2009.

SETTING

This was a global noninterventional surveillance study.

MAIN OUTCOME MEASURE(S)

Long-term monitoring of safety, including central magnetic resonance imaging (MRI) reading and treatment outcomes, was measured.

RESULTS

Subjects (n = 1288) were treated with pegvisomant for a mean of 3.7 yr and followed up in ACROSTUDY for a mean of 2.1 yr. A total of 1147 adverse events (AE) were recorded in 477 subjects (37%), among which 192 AE in 124 subjects (9.6%) were considered to be related to pegvisomant. Serious AE were recorded in 159 subjects (12.3%), whereas pegvisomant-related Serious AE were recorded in 26 subjects (2%). No deaths (15 subjects; 1.2%) were attributed to pegvisomant use. The incidence of increase in pituitary tumor size in the subset with confirmed MRI increases on central reading represented 3.2% of the overall cohort with at least two available MRI (n = 936). Injection-site reactions were reported in 28 cases (2.2%). In 30 patients (2.5%), an elevated aspartate aminotransferase or alanine aminotransferase of more than 3 times the upper level of normality was reported. There were no reports of liver failure. After 5 yr of pegvisomant treatment, 63.2% of subjects had normal IGF-I levels at a mean dose of 18 mg/d.

CONCLUSIONS

Data entered and evaluated in ACROSTUDY indicate that pegvisomant is an effective and safe medical treatment in patients with acromegaly. The reported low incidence of pituitary tumor size increase, liver enzyme elevations, and lipodystrophy at the injection site are reassuring.

What is active acromegaly and which parameters do we have?

Disease activity of acromegaly can be measured in many ways. Growth hormone (GH) and insulin-like growth factor 1 (IGF1) concentrations are the main biochemical markers used to measure the response to treatment. Both GH and IGF1 have been associated with prognosis, in particular mortality. In this review, we discuss the available parameters to assess disease activity in acromegaly.

Effects of chronic slow release-lanreotide treatment on insulin-like growth factor system and metabolic parameters in acromegalic patients

Insulin and IGF binding protein (IGFBP)-1 are linked by negative association. Somatostatin (SS) reduces insulin secretion by acting on pancreatic β-cell and also by decreasing GH secretion. SS analogues in acromegaly reduce total IGF-I levels inhibiting GH hypersecretion, but they also reduce free IGF-I bioactivity increasing IGFBP-1 levels by inducing insulin decrease. In 13 acromegalic patients we studied GH, IGF system, insulin, and glucagon levels at baseline and at 7 days, 1 and 6 months under treatment with slow release (SR)-lanreotide (LAN) (60 mg im monthly). The hormonal and metabolic response to arginine (ARG) (0.5 g/kg iv in 30 min) was also studied at each time point. LAN decreased GH, total IGF-I, and IGFBP-3 levels at each time point. Insulin and glucagon levels were reduced, while IGFBP-1 and free IGF-I levels were increased by LAN at day 7 and after 1 month only. LAN did not modify the GH, insulin, glucagon, glucose, and IGFBP-1 responses to ARG. At each time point ARG-induced insulin increase was coupled to increase in glucagon and IGFBP-1 levels. This study shows that acromegalic patients under chronic treatment with LAN display: a) inhibition of GH and total IGF-I levels, not coupled to persistent decrease in free IGF-I levels; b) persistent decrease in IGFBP- 3 but transient decrease and increase in insulin and IGFBP- 1, respectively; c) unchanged hormonal and metabolic response to ARG. Our findings also show that ARG stimulates IGFBP-1 despite marked increase in insulin secretion; this escape from the negative relationship linking insulin and IGFBP- 1 would likely reflect the ARG-induced glucagon increase.

The hypercoagulable state in Cushing's disease is associated with increased levels of procoagulant factors and impaired fibrinolysis, but is not reversible after short-term biochemical remission induced by medical therapy

CONTEXT

Cushing's disease (CD) is accompanied by an increased risk of venous thromboembolism. Surgery is the primary treatment of CD.

OBJECTIVE

The aim of the study was to compare hemostatic parameters between patients with CD and controls and to evaluate the effect of medical treatment of CD on hemostasis.

DESIGN AND SETTING

During 80 d, stepwise medical treatment was applied with the somatostatin analog pasireotide, the dopamine agonist cabergoline, and ketoconazole, which suppresses adrenocortical steroidogenesis, at four university medical centers in The Netherlands.

PATIENTS

Seventeen patients with de novo, residual, or recurrent CD were included.

MAIN OUTCOME MEASURES

We measured urinary free cortisol and parameters of coagulation and fibrinolysis.

RESULTS

Patients with CD had significantly higher body mass index (P < 0.001), shortened activated partial thromboplastin time (P < 0.01), and higher levels of fibrinogen, Factor VIII, and protein S activity (P < 0.05) compared to healthy control subjects. In addition, fibrinolytic capacity was impaired in patients with CD as reflected by prolonged clot lysis time (P < 0.001) and higher levels of plasminogen activator inhibitor type 1, thrombin-activatable fibrinolysis inhibitor, and α2-antiplasmin (P < 0.01). There were no statistically significant differences in von Willebrand factor:antigen, antithrombin, and protein C activity. After 80 d, 15 of 17 patients had normalized urinary free cortisol excretion. Despite biochemical remission, only slight decreases in antithrombin (P < 0.01) and thrombin-activatable fibrinolysis inhibitor (P < 0.05) levels were observed. Other parameters of coagulation and fibrinolysis did not change significantly.

CONCLUSIONS

The hypercoagulable state in patients with CD, which is explained by both increased production of procoagulant factors and impaired fibrinolysis, is not reversible upon short-term biochemical remission after successful medical therapy. This may have implications for the duration of anticoagulant prophylaxis in patients with (cured) CD.

Pegvisomant and improvement of quality of life in acromegalic patients

BACKGROUND

Acromegaly is a growth disorder, but mostly it is a metabolic disease related to excessive production of growth hormone (GH). It is characterized by progressive somatic disfigurement in combination with sometimes severe systemic manifestations. Long-acting somatostatin analog (SSA) therapy normalizes serum insulin-like growth factor I (IGF-I) levels in approximately 55% of patients, but we postulate that these patients still have acromegaly in many tissues other than the liver. Direct and indirect effects of SSA reduce hepatic IGF-I generation and make the liver behave as if it is GH resistant. The remaining 'peripheral' or non- hepatic acromegaly has a significant negative impact on the quality of life of these patients.

CONCLUSIONS

Pegvisomant is the most effective medical treatment for acromegaly. Due to its mode of action and pharmacodynamic properties, it is the ideal partner for combination therapy with an SSA for acromegalic patients with a remaining, peripheral form of the disease.

Rapid decrease in adrenal responsiveness to ACTH stimulation after successful pituitary surgery in patients with Cushing's disease

OBJECTIVE

The aim of this study was to investigate the effects of transsphenoidal surgery (TS) on the adrenal sensitivity to ACTH (adrenocorticotropin) stimulation in patients with Cushing's disease (CD).

METHODS

We measured the cortisol response to 1 μg synthetic ACTH (1-24) 6 days after pituitary surgery in 45 patients with CD. Mean follow-up period was 56·5 months (SE 4·7).

RESULTS

In 24 of 28 patients in sustained remission after pituitary surgery, peak cortisol concentrations below 774 nm (28·0 μg/dl) were recorded after stimulation with 1 μg synthetic ACTH (86%). Two patients with recurrent disease after initial remission (late relapse) also showed ACTH-stimulated peak cortisol levels below 774 nM. Fourteen of 15 patients with persistent CD after surgery (early failure) showed absolute peak cortisol levels >774 nm in response to ACTH stimulation.

CONCLUSION

Patients in remission after pituitary surgery for CD showed a rapid decrease of adrenal responsiveness to exogenous ACTH stimulation. This phenomenon may be explained by ACTH-receptor down-regulation in the adrenal cortex after complete removal of the pituitary corticotroph adenoma. In our study, the postoperative low-dose ACTH stimulation test had a sensitivity of 93% and a specificity of 87% in predicting immediate remission of CD after pituitary surgery.