Pegvisomant in acromegaly: why, when, how

The Interplay Between Pituitary Health and Diabetes Mellitus - The Need for 'Hypophyseo-Vigilance'

The anterior and posterior hypophyseal hormones alter glucose metabolism in health and disease. Secondary diabetes may occur due to hypersecretion of anterior pituitary hormones like adrenocorticotrophic hormone in Cushing's disease and growth hormone in acromegaly. Other hormones like prolactin, gonadotropins, oxytocin and vasopressin, though not overtly associated with causation of diabetes, have important physiological role in maintaining glucose homeostasis. Hypoglycaemia is not an unusual occurrence in hypopituitarism. Many of the medications that are used for treatment of hypophyseal diseases alter glucose metabolism. Agents like pasireotide should be used with caution in the setting of diabetes, whereas pegvisomant should be given preference. Diabetes mellitus itself, on the other hand, can alter the functioning of hypothalamic pituitary axis; this is documented in both type 1 and type 2 diabetes. This review focuses on the clinically relevant interplay of hypophyseal hormones and glucose homeostasis. The authors define 'hypophyseo-vigilance' as an approach which keeps the bidirectional, multifaceted interactions between the pituitary and glucose metabolism in mind while managing diabetes and pituitary disease.

Management of acromegaly: an exploratory survey of physicians from the Middle East and North Africa

BACKGROUND

Worldwide variations exist in the diagnosis and management of patients with acromegaly. For such a rare condition, the knowledge and perception of physicians would most likely direct the care of patients. However, the adherence of physicians in non-Western regions to guidelines for the diagnosis and management of acromegaly has not been previously ascertained.

METHODS

An online survey was conducted to assess the perceptions and practice of physicians regarding acromegaly diagnosis and management as per international guidelines. An electronic questionnaire containing key questions was mailed, initially to physicians in Saudi Arabia (KSA) and later to other countries in the Middle East and North Africa (MENA) region. Additional questions were included to ensure the relevance of the respondents' replies. The responses were captured and summarized anonymously. Descriptive comparisons were made with two similar international and national surveys from other regions.

RESULTS

Two hundred forty-seven doctors responded to the survey. Of these, 155 (64.5%) fulfilled the inclusion criteria and, in particular, confirmed having treated acromegaly patients in the previous 12 months, and they constituted the basis of this study. The three most common referring specialties for patients were internists (44; 28.4%), neurosurgeons (46; 29.6%), and family medicine physicians (42; 27.1%), respectively. The combination of growth hormone (GH) nadir during the oral glucose tolerance test (OGTT) and elevated insulin-like growth factor-1 (IGF-1) levels was used by 99 physicians (63.9%) to diagnose acromegaly. The main determinant for treatment choice was tumor mass characteristics confirmed by 117 respondents (75.5%) with neurosurgery as first treatment choice confirmed by 124 respondents (80%). Combined measurement of IGF-1 and GH levels after OGTT at 3 months after surgery was the most widely used criterion for assessment of surgical outcomes, confirmed by 82 physicians (52.9%). The biggest barriers to optimal management of acromegaly as perceived by 38.1% and 35.5% of the respondents were high cost of medications and lack of physicians' awareness, respectively.

CONCLUSIONS

The majority of the surveyed physicians reported variable adherence to the international acromegaly guidelines. Clearly, higher awareness is needed among physicians for early diagnosis and timely referral for specialist management.

How to improve effectiveness of pegvisomant treatment in acromegalic patients

PURPOSE

Pegvisomant (PEGV) treatment in acromegaly patients resistant to somatostatin analogues is less effective in the real life than in clinical trials. This is a multicenter, observational, retrospective, longitudinal study. The aim was to detect characteristics which improve long-term PEGV effectiveness.

METHODS

87 acromegalic patients treated with PEGV have been enrolled in seven referral Italian centres. PEGV was administered for up to 4 years, at doses up titrated until IGF-1 normalization or to ≥ 30 mg/day. The rate of patients who reached IGF-1 normalization at last visit has been calculated.

RESULTS

IGF-1 was normalized in 75.9% of patients after 1 year and in 89.6% at last visit. Disease control was associated with lower baseline GH, IGF-1 and IGF-1 xULN and was more frequent when baseline IGF-1 was < 2.7 × ULN (p < 0.02). PEGV dose was dependent on baseline IGF-1 > 2.7 × ULN (p < 0.05) and doses > 1.0 mg/BMI/day were administered more frequently when baseline IGF-1 was > 2.0 × ULN (p = 0.03). PEGV resistance was associated with higher BMI (p = 0.006) and was more frequent when BMI was > 30 kg/m² (p = 0.07). There were no significant differences between patients treated with monotherapy or combined treatment. IGF-1 normalization, PEGV dose and rate of associated treatment were similar between males and females. PEGV effectiveness was independent from previous management. Diabetic patients needed higher doses of PEGV than non-diabetic ones.

CONCLUSIONS

PEGV effectiveness improves when up titration is appropriate. Higher PEGV doses at start and a more rapid up-titration are necessary in patients with obesity and/or IGF-1 > 2.7 × ULN.

Pegvisomant in acromegaly: an update

BACKGROUND

In 2007, we published an opinion document to review the role of pegvisomant (PEG) in the treatment of acromegaly. Since then, new evidence emerged on the biochemical and clinical effects of PEG and on its long-term efficacy and safety.

AIM

We here reviewed the emerging aspects of the use of PEG in clinical practice in the light of the most recent literature.

RESULTS

The clinical use of PEG is still suboptimal, considering that it remains the most powerful tool to control IGF-I in acromegaly allowing to obtain, with a pharmacological treatment, the most important clinical effects in terms of signs and symptoms, quality of life and comorbidities. The number of patients with acromegaly exposed to PEG worldwide has become quite elevated and the prolonged follow-up allows now to deal quite satisfactorily with many clinical issues including major safety issues, such as the concerns about possible tumour (re)growth under PEG. The positive or neutral impact of PEG on glucose metabolism has been highlighted, and the clinical experience, although limited, with sleep apnoea and pregnancy has been reviewed. Finally, the current concept of somatostatin receptor ligands (SRL) resistance has been addressed, in order to better define the acromegaly patients to whom the PEG option may be offered.

CONCLUSIONS

PEG increasingly appears to be an effective and safe medical option for many patients not controlled by SRL but its use still needs to be optimized.

Somatostatin analogs, cabergoline and pegvisomant: comparing the efficacy of medical treatment for acromegaly

Therapies for acromegaly aim at normalizing hormonal excess and controlling tumor growth . Therapeutic approaches are surgery, pharmacotherapy and radiotherapy. Area covered: This review focuses on the role of medical therapy of acromegaly, comparing the efficacy of somatostatin analogues (SSA), dopamine-agonists (DA) and pegvisomant (PEG), the three available drug classes for treating acromegaly. To clarify the difference in response rates reported in the literature for these therapies, we performed a search for original articles published in PubMed. SSA represent the first-line approach to medical treatment. This therapy is effective in controlling acromegaly in about 40% of patients, however there are great differences in the reported hormonal efficacy of SSA in the different series. In patients partially resistant to SSA, cabergoline can be added when hormonal levels are close to normalization, resulting effective in control IGF-I levels in 43% of patients. In patients with higher hormonal levels PEG is indicated, normalizing IGF-I levels in 79.8% and 80.6% of cases when used in monotherapy or in combination with SSA. Pasireotide, the newly developed SSA multi-ligand receptor, represents a new option in SSA resistant patients. Expert commentary: Medical therapy represents an important therapeutic option resulting safe and effective in controlling acromegaly in a high percentage of patients. The best treatment should be individually tailored for each patient, taking into account sex, age, comorbidities, tumor characteristics and hormonal levels.

Does pegvisomant treatment expertise improve control of resistant acromegaly? The Italian ACROSTUDY experience

OBJECTIVE

GH receptor antagonist pegvisomant is indicated for treatment of patients with resistant acromegaly. We compared safety and treatment outcomes of pegvisomant therapy in patients managed by Italian centers enrolling less or more than 15 cases in ACROSTUDY, a safety surveillance study of long-term pegvisomant treatment of patients with acromegaly. A noninterventional safety surveillance study in which safety and treatment outcomes of pegvisomant were evaluated on the basis of data collected during a 7-year period.

METHODS

A total of 204 acromegaly patients treated by seven centers enrolling 16-49 patients each (group A) and 137 subjects by 18 centers following 3-14 cases ( group B).

RESULTS

Patients of group A and B were treated for 4.4 ± 2.7 and 4.2 ± 2.2 years, respectively. IGF-1 ULN normalized in 64.4 % (n = 56) and 54.4 % (n = 31) in group A and B, respectively, after 1-year treatment, and in 57.3 % (n = 106) and 72.5 % (n = 87) at last visit. Starting doses were significantly higher in group A. They were progressively increased during treatment in both groups, but were higher in uncontrolled patients than in controlled ones only in group A. Reported adverse events were more frequent, and the prevalence of patients with adverse events was higher in group B.

CONCLUSIONS

On the basis of this original study approach, we could speculate that in the centers in which more patients are treated with pegvisomant, less adverse events are reported, but the long-term effectiveness is lower than in centers with less cases, perhaps because of an inadequate patient's selection.

ACROSTUDY: the Italian experience

ACROSTUDY is a world-wide non-interventional, post marketing surveillance study performed to monitor the safety and outcomes of pegvisomant (PEG) in clinical practice. We report data from acromegaly patients who have been included in the Italian ACROSTUDY registry. The data of 341 acromegaly patients (171 males) were available for analysis using data freeze (12/9/2012). Patients were enrolled in 25 Italian endocrine centres. Before and during PEG treatment IGF-I, liver enzymes, metabolic parameters, and pituitary MRI were assessed. Before PEG, 54.3% patients had been treated with medical therapy and surgery, 22.9% medical therapy only, and 15.8% medical plus radiation and surgical therapy. 199 adverse events were reported in 98 patients (28.7%). Serious adverse events were documented in 29 patients (8.5%). 71.1% of patients had no significant change in tumor volume. Central MRI reading was performed in 34 patients; in 7 patients, an increase in tumor volume was found. Hormonal efficacy progressively increased since the start of PEG. After 6 years, normal IGF-I levels were found in 70.9% of patients (mean daily dose 18.1 mg). 87.1% of patients were treated with daily PEG although in 8.8% of patients, it was administered 2-6 times per week and in 3.8% with weekly injections. 74.8% received a PEG dose 10-15 mg/daily. PEG is a drug with a favorable safety profile which is efficacious also considering that in Italy it is currently available as third-line therapy.

Cardiovascular events in acromegaly: distinct role of Agatston and Framingham score in the 5-year prediction

Prediction of ischemic cardiovascular events (ICE) in acromegalic patients stratified accordingly with Framingham (FS) and Agatston score (AS). 32 patients with active (group A (0)) and 20 with controlled (group B (0)) acromegaly have been enrolled. During the 5-year follow-up, 19 out of 32 patients in group A (0) reached disease control. At entry, FS and AS, by an eight-slice MDCT scanner, were calculated in all patients. ICE were diagnosed by autopsy, if lethal, and by electrocardiography and/or echocardiography, if non-lethal. Overall, 9.6 % of patients died for lethal ICE. AS >400, but not high FS at entry, was associated with increased risk of lethal ICE. Lethal ICE had occurred in two patients of group A (0) and three of group B (0) (p NS), while a non-lethal ICE had occurred in two cases of the former and in other two of the latter group (p NS). Either FS or AS was correlated with the risk for ICE overall (p < 0.02), but only AS correlated with that of lethal ICE (p < 0.0003). Survival analysis demonstrated reduced life expectancy in patients with high FS (p < 0.02). In acromegalics, AS >400 is associated with increased risk of lethal ICE, while high FS is associated with reduced life expectancy, regardless of disease control.

MTHFR C677T polymorphism, folate status and colon cancer risk in acromegalic patients

BACKGROUND

Acromegalic patients have a higher risk of developing colorectal tumours (CRT). The common C677T polymorphism in methylenetetrahydrofolate reductase (MTHFR) gene is a well-documented CRT risk factor in the general population, but its role in acromegaly has never been examined.

PURPOSE

We investigated the influence of MTHFR C677T polymorphism, folate status and other lifestyle, nutritional and disease-specific variables on CRT risk in acromegaly.

METHODS

Clinical data were collected from 115 acromegalic patients (25 with active disease) who underwent a complete colonoscopy. C677T MTHFR genotype, homocysteine, vitamin B12, insulin growth factor and insulin levels, as well as metabolic variables were evaluated.

RESULTS

Colorectal tumours were identified in 51 patients (3 adenocarcinomas). MTHFR C677T distribution was in the Hardy-Weinberg equilibrium and similar in patients with or without CRT. There was a correlation between patients with TT genotype and CRT occurrence (Spearman's test: P = 0.03), with an Odds Ratio (OR) of 1.32 (95% CI 0.522-3.362, P NS). A folate-MTHFR genotype interaction on CRT risk was found (P = 0.037): in the lower folate subgroup, TT patients showed a 2.4 higher OR for CRT (95% CI 0.484-11.891; P NS) than C-allele carriers. Smoking (P = 0.007), increased HbA1c levels (P = 0.021), dyslipidaemia (P = 0.049), acromegaly control (P = 0.057), and folate-MTHFR genotype interaction (P = 0.088) were associated with CRT at multivariate analysis.

CONCLUSIONS

In this cohort of acromegalic patients, CRT risk is increased in 677TT MTHFR patients with low plasma folate levels. Smoking, high HbA1c levels, dyslipidaemia and disease activity were also associated with increased CRT risk.

HGF/c-met system targeting PI3K/AKT and STAT3/phosphorylated-STAT3 pathways in pituitary adenomas: an immunohistochemical characterization in view of targeted therapies

The ligand/receptor hepatocyte growth factor (HGF)/c-met signaling system promotes cellular growth and angiogenesis through PI3K/phosphor-Akt and STAT3/phosphor-STAT3 downstream effectors. In this study, we have evaluated the expression of molecules of the HGF/c-met pathway in pituitary adenomas (PA). The expression of HGF, c-met, PI3K (p85αsubunit) pAkt, STAT3, and pSTAT3 was analyzed by immunohistochemistry in an archival series of 30 PA (12 non-functioning and 18 functioning; 25 macroadenomas and 5 microadenomas). PAs expressed all six proteins in tumor epithelial cells. The proportion of c-met(+ve) cells was greater than HGF(+ve) cells (49 ± 19 vs 34 ± 17 %, P < 0.01), the pAkt(+ve) cells greater than PI3K(+ve) cells (39 ± 16.0 vs 1.3 ± 0.5 %, P < 0.001), and the STAT3(+ve) cells greater than active pSTAT3(+ve) cells (14 ± 8 vs 7 ± 6 %, P < 0.01). Furthermore, endothelial Akt immunostaining was detected on the vascular surface area of 17 PAs, in macroadenomas more frequently than in microadenomas (82 vs 18 %). The percentage of immunostained endothelial cells was greater in macro than in microadenomas (19 ± 7 and 7 ± 3 %; P < 0.05). In conclusion, HGF and c-met are widely expressed in PA, and correlate with pAkt expression. These data, together with the finding of pAkt immunostaining on microvascular areas related to tumor size, suggest a major role of the pAKT signaling in tumor growth and angiogenesis. There might be practical implications for the targeted therapy of PA.

Octreotide for acromegaly treatment: a reappraisal

INTRODUCTION

Acromegaly is a rare disorder characterized by excess secretion of growth hormone (GH) generally caused by a pituitary macroadenoma and associated with reduced life expectancy if the disease is untreated. This article covers the recent available evidences published on octreotide , the first somatostatin analog introduced into clinical practice for the medical treatment of acromegaly.

AREAS COVERED

This article discusses i) pharmacology of somatostatin and octreotide; ii) biochemical effects of regular octreotide and long-acting repeatable formulation; iii) tumor shrinkage effects of octreotide in acromegaly; iv) impact of octreotide on acromegalic clinical manifestations and chronic complications; v) safety of octreotide and vi) place of octreotide in the guidelines for acromegaly treatment. Full-text articles in the English language were selected from a PubMed search spanning 1984 - 2013, for keywords including 'octreotide,' 'acromegaly,' 'GH,' 'IGF-I,' and 'tumor shrinkage.' Reference lists in selected papers were also used to broaden the search.

EXPERT OPINION

Octreotide is a mature drug with a consolidated favorable benefit versus risks profile in the treatment of acromegaly.

Investigational therapies for acromegaly

INTRODUCTION

The treatment of acromegaly aims at normalizing growth hormone (GH) and insulin-like growth factor (IGF-I) levels and controlling tumor growth. The approaches to therapy are essentially three: surgery and pharmacotherapy, alone or in combination, and radiotherapy, generally used in more aggressive tumors.

AREAS COVERED

This review focuses on the novel drug formulations being developed for medical therapy of acromegaly. Even though many efficient treatments have been made available to manage acromegaly in the last two decades, a significant number of patients remain still uncontrolled. Medical therapy represents an important therapeutic option and can be used as the first-line treatment in many patients. However, roughly 25% of patients might be considered as poor responsive or resistant to conventional long-acting somatostatin analogs (SSA) treatment. Therefore, new longer-acting SSA, oral SSA formulations, new combined therapies with weekly doses of pegvisomant, combination therapy with pegvisomant (PEG) and cabergoline (CAB) or SSA and new approaches have been proposed. New molecules are currently under investigation in clinical trials, such as the SSA multi-receptor ligand, pasireotide, which represents a promising option therapy, especially in patients not adequately controlled with currently available SSA. Further, temozolomide has been suggested as an efficient drug for treating GH-aggressive pituitary tumors resistant to conventional therapy.

EXPERT OPINION

All these novel SSA formulations and new molecules implement the available options in therapies of acromegaly to improve disease control. However, further studies are needed to define the exact role of these newer agents. The predicting factors for response to these new therapies should also be determined.

Glycometabolic control in acromegalic patients with diabetes: a study of the effects of different treatments for growth hormone excess and for hyperglycemia

BACKGROUND

Diabetes mellitus is frequently observed in patients with acromegaly. Current therapies for acromegaly may impact glucose regulation, influencing insulin sensitivity and secretion. The question whether these therapies modify control and progression of diabetes once present is still open.

AIM

Aim of our study is to analyze glucose control in acromegalic patients with diabetes, evaluating the relation with treatments for GH excess and for diabetes.

METHODS

Seventy patients with acromegaly and diabetes were studied. Duration and treatments of acromegaly and diabetes were recorded, together with clinical and metabolic parameters.

RESULTS

Most patients (92.8%) were treated with somatostatin analogs (SSA), either alone or in combination with dopamine-agonists (20%) or pegvisomant (15.7%); 7.1% of patients had been treated by surgery alone. Metformin (65.7%), alone or in combination with other hypoglycemic drugs, was the most frequent treatment for diabetes, followed by insulin (21.5%). Only 15.7% were treated with diet alone. The whole cohort showed a very good control of diabetes and acromegaly. Median glycated hemoglobin was 6.4% (5.9-7). IGF-I was within normal range for age in most patients. No relation was observed between duration of acromegaly or diabetes and metabolic control. SSA had a negative effect on insulin secretion, but these effects did not influence glucose control. Finally, we observed a low prevalence of nephropathy (6%) and retinopathy (20%).

CONCLUSIONS

Our study shows that a good control of hyperglycemia can be obtained with success in the majority of acromegalic patients with diabetes, independently of the type of treatment for GH excess.

Current management practices for acromegaly: an international survey

To determine whether peer-reviewed consensus statements have changed clinical practice, we surveyed acromegaly care in specialist centers across the globe, and determined the degree of adherence to published consensus guidelines on acromegaly management. Sixty-five acromegaly experts who participated in the 7th Acromegaly Consensus Workshop in March 2009 responded. Results indicated that the most common referring sources for acromegaly patients were other endocrinologists (in 26% of centers), neurosurgeons (25%) and primary care physicians (21%). In sixty-nine percent of patients, biochemical diagnoses were made by evaluating results of a combination of growth hormone (GH) nadir/basal GH and elevated insulin like growth factor-I (IGF-I) levels. In both Europe and the USA, neurosurgery was the treatment of choice for GH-secreting microadenomas and for macroadenomas with compromised visual function. The most widely used criteria for neurosurgical outcome assessment were combined measurements of IGF-I and GH levels after oral glucose tolerance test (OGTT) 3 months after surgery. Ninety-eight percent of respondents stated that primary treatment with somatostatin receptor ligands (SRLs) was indicated at least sometime during the management of acromegaly patients. In nearly all centers (96%), the use of pegvisomant monotherapy was restricted to patients who had failed to achieve biochemical control with SRL therapy. The observation that most centers followed consensus statement recommendations encourages the future utility of these workshops aimed to create uniform management standards for acromegaly.

Role of the addition of cabergoline to the management of acromegalic patients resistant to longterm treatment with octreotide LAR

The aim of this prospective open trial was to evaluate the efficacy in normalizing IGF-I levels of the addition of cabergoline to the treatment of acromegalic patients partially responsive to Octreotide-LAR (OCT-LAR), a long acting somatotastin analog (SSA). Fifty-two patients who did not achieve hormonal control after longterm therapy (at least, 12 months) with OCT-LAR (30 mg every 28 days intramuscularly) were given cabergoline in addition to the SSA treatment. Normalization of IGF-I levels was achieved in 40.4% of patients by 6 months after the addition of cabergoline (1.0-3.0 mg/week; mean, 2.19 ± 0.64), and these patients were considered responsive. Compared to non-responsive subjects, responsive patients had significantly lower mean %ULNR-IGF-I and GH levels. However, the rate of hyperprolactinemia and positive immunohistochemical staining for PRL was similar in both groups, before the addition of cabergoline. Responsive patients were followed for at least 12 months on combination treatment and persisted with normal IGF-I levels. Patients with baseline %ULNR IGF-I up to 220% and/or GH up to 5 ng/ml were those who benefited the most from combination treatment. No patients with %ULNR-IGF-I>250% reached normalization of IGF-I levels. Our findings demonstrated that the addition of cabergoline, even at relatively low doses, is effective in both short- and long-term control of IGF-I levels in acromegalic patients partially responsive to octreotide LAR, particularly in those with mild/moderately elevated GH/IGF-levels, irrespective of prolactin status.

Short- and long-term changes of quality of life in patients with acromegaly: results from a prospective study

Quality of life (QoL) may be affected in acromegalic patients, although the role of disease activity is still unsettled. The aim of the study was to assess the QoL of acromegalic patients with a specific questionnaire (ACROQOL). ACROQOL was evaluated in a prospective study (at baseline, at 6 and 24 months) in 23 active untreated acromegalic patients. Control of acromegaly was defined by normal age-matched serum IGF-I concentrations. Patient groups were defined as controlled or uncontrolled at 6 months and at 24 months: controlled or uncontrolled during the entire study period (ACRO(CC) or ACRO(NC), respectively) or uncontrolled at 6 months and controlled thereafter (ACRO(C)). At 6 months, ACROQOL scores improved globally (from 54.3+/-21 to 65.1+/-19, p=0.04) as did subdomains and were inversely related to IGF-I variation (r=-0.50, p=0.052). At 24 months, ACROQOL improved globally (from 54.3+/-21 to 65.7+/-18.0, p=0.04) and this was also seen in the appearance subdomains; however, no correlation was revealed between variation of serum IGF-I concentrations and changes in ACROQOL total score (r=0.008, p=0.87). ACROQOL scores did not significantly change in ACRO(NC) (p=0.310) and in ACRO(C) (p=0.583), whereas it improved globally (from 42.1+/-22.1 to 58.8+/-16.04, p=0.021) and in psychological subdomains in ACRO(CC); however, it reflected the improvement occurred within the first 6 months of disease control. In conclusion, successful treatment, which normalizes disease activity, improves QoL in acromegaly in the short term. However, the lack of correlation between the ACROQOL score in the long term might suggest that factors other than serum IGF-I participate in the well-being of acromegalic patients; however, due to the small sample size, our results need to be confirmed in larger studies.

Comparison of pegvisomant and long-acting octreotide in patients with acromegaly naïve to radiation and medical therapy

BACKGROUND

Normalization of IGF-I in patients with acromegaly is associated with a decrease in mortality. Pegvisomant may be more effective in lowering IGF-I than octreotide.

SUBJECTS AND METHODS

The efficacy and safety of pegvisomant and octreotide long-acting release (LAR) were compared in 118 patients with acromegaly in this 52-week, multicenter, open-label, randomized study. The primary endpoint was IGF-I normalization at week 52. Secondary endpoints included mean changes from baseline in IGF-I, IGF binding protein 3, acromegaly signs and symptom scores, ring size, acromegaly quality of life questionnaire scores, and safety.

RESULTS

Fifty-six patients received pegvisomant and 57 received octreotide LAR. IGF-I normalized in 51% of pegvisomant patients and 34% treated with octreotide LAR (p=0.09, ns). Patients with baseline IGF-I > or = 2x upper limit of normal had a higher rate of IGF-I normalization with pegvisomant vs octreotide LAR (p=0.05). Among the patients who did not achieve a normalized IGF-I, pegvisomant-treated patients were more likely to be receiving < 30 mg of study drug (71% vs 16%). Treatment-related adverse events were mild-to-moderate in both groups. Mean fasting glucose decreased in diabetic and non-diabetic patients on pegvisomant whereas octreotide LAR was associated with an increase at week 52 (p=0.005 and p=0.003 between groups, respectively). Mean change in tumor volume during treatment was similar between groups.

CONCLUSIONS

Pegvisomant and octreotide LAR were equally effective in normalizing IGF-I in the overall population, and pegvisomant was more effective in patients with higher baseline IGF-I levels. Pegvisomant had a more favorable effect on parameters of glycemic control.

Secondary diabetes associated with principal endocrinopathies: the impact of new treatment modalities

The secondary occurrence of type 2 diabetes with various hormonal diseases (e.g. pituitary, adrenal and/or thyroid diseases) is a recurrent observation. Indeed, impaired glucose tolerance (IGT) and overt diabetes mellitus are frequently associated with acromegaly and hypercortisolism (Cushing syndrome). The increased cardiovascular morbidity and mortality associated with acromegaly and Cushing syndrome may partly be a consequence of increased insulin resistance that normally accompanies hormone excess. Acromegalic patients are insulin resistant, both in the liver and in the periphery, displaying hyperinsulinemia and increased glucose turnover in the basal post-absorptive states. The prevalence of diabetes mellitus and that of IGT in acromegaly is reported to range 16-56%, whereas the degree of glucose tolerance seems correlated with circulating growth hormone (GH) levels, age, and disease duration. Moreover, a family history of diabetes and concomitant presence of arterial hypertension have been found to predispose to diabetes as well. GH has physiological effects on glucose metabolism, stimulating gluconeogenesis and lipolysis, which results in increased blood glucose and free fatty acid levels. Conversely, insulin-like growth factor 1 (IGF-I) enhances insulin sensitivity primarily on skeletal muscles. However, in acromegaly, increased IGF-I levels are unable to counteract the insulin-resistance status determined by GH excess. Therapy with somatostatin analogues (SSAs) induce control of GH and IGF-I excess in the majority of patients, but their inhibitory effect on pancreatic insulin secretion might complicate the overall effect of this treatment on glucose tolerance. Hypercortisolism produces visceral obesity, insulin resistance, and dyslipidemia that together with hypertension, hypercoagulability, and ventricular morphologic and functional abnormalities increase cardiovascular risk, and persist up to 5 years after resolution of hypercortisolism. Hypercortisolism leads to hyperglycaemia and reduced glucose tolerance, determines insulin resistance, stimulates hepatic gluconeogenesis and glicogenolisis. In Cushing syndrome the prevalence of diabetes varies between 20 and 50%, but probably this prevalence is underestimated, as not always an oral glucose tolerance test is performed in the presence of an apparently normal fasting glycaemia. Again, disease duration, rather than hormone levels, seems to be the major determinant in the occurrence of systemic complications in Cushing syndrome. Due to the impact they have on mortality and morbidity in both acromegaly and Cushing syndrome, these complications should be treated aggressively. In patients with neuroendocrine tumours (NETs) the occurrence of altered glucose tolerance may be due to a decreased insulin secretion, like it happens in patients who underwent pancreatic surgery and in those with pheochromocytoma, or to an altered counterbalance between hormones, such as in patients with glucagonoma and somatostatinoma. Moreover, SSAs represent a valid therapeutic choice in the symptomatic treatment of NETs, and also in this case the medical therapy of the primary disease, may have a significant impact on the prevalence of glucose metabolism imbalance. In thyroid disorders, an abnormal glucose tolerance may be principally encountered in hyperthyroidism. The pathogenesis is complex and scant data on prevalence and severity are found in the literature. Adequate treatment for glucose imbalance is mandatory in these peculiar patients in line with the American Diabetes Association and the European Association for the Study of Diabetes consensus statement. In particular, since traditional insulins have two features that may complicate therapy (absorption profiles, delayed onset of action and peak activity), the new insulin analogues could be of particular interest in the management of the secondary diabetes associated with endocrinopathies, considering the frailty of these patients. Indeed, it has been demonstrated that insulin glargine, given once daily, reduces the risk of hypoglycaemia compared with other formulations, and can facilitate a more aggressive insulin treatment in this class of patients.

Potential role of type I interferons in the treatment of pituitary adenomas

Cytokines, particularly those endowed with pro-inflammatory properties, are known to influence the release of anterior pituitary hormones by a direct and indirect action at the level of pituitary gland and hypothalamus. Type I interferons (IFNs) represent a group of cytokines that act through a common receptor composed by two chains (IFNAR-1 and IFNAR-2). Several in vitro and in vivo studies underline the fact that type I IFNs are involved in the regulation of the immune-endocrine circuitry. Treatment with type I IFNs of patients affected by chronic viral hepatitis, multiple sclerosis and tumors influences the secretion of pituitary hormones. This article reviews the current knowledge about the effects of IFN-alpha and IFN-beta on hypothalamic-pituitary function and describes the potential role of type I IFNs in the treatment of pituitary adenomas.

Advances in the Diagnosis, Treatment, and Molecular Genetics of Pituitary Adenomas in Childhood

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Clinical and biochemical impact of the d3 growth hormone receptor genotype in acromegaly

CONTEXT

Lack of exon 3 of the GH receptor (d3-GHR) has been associated with increased responsiveness to GH therapy. By analogy, we hypothesized that patients with acromegaly bearing the d3-GHR genotype may have a more morbid clinical and biochemical picture.

OBJECTIVE

Our objective was to determine whether the GHR genotype, by modifying tissue sensitivity to GH, influences the clinical/biochemical expression of acromegaly and its outcome after treatment.

SETTING

The study was conducted at a specialized clinic at a tertiary care hospital.

DESIGN, PATIENTS, AND METHODS

We conducted a prospective genotype investigation and retrospective analysis and correlation with clinical, biochemical, and outcome data from a group of 148 patients. Samples from 175 healthy blood donors were used as controls. GHR genotyping was performed by real-time PCR.

MAIN OUTCOME MEASURES

We assessed prevalence of the three GHR genotypes (fl/fl, d3/d3, and d3/fl), associations between the genotypes, and baseline as well as post-therapeutic characteristics.

RESULTS

Prevalence of the fl/fl, d3/d3, and d3/fl genotypes was 45, 22, and 32%, respectively, similar to what was found in the controls. Baseline characteristics were similar in carriers of the three genotypes. A positive correlation between IGF-I and log GH concentrations was significant only in homo- or heterozygous d3 carriers. Among d3-GHR carriers, diabetes, but no other comorbidities, was more prevalent (odds ratio = 2.02; 95% confidence interval = 0.96-4.2). d3-GHR carriers had significantly higher IGF-I concentrations after treatment. Multiple regression analysis revealed that the homo- or heterozygous lack of exon 3 was the strongest predictor of persistent biochemical activity (odds ratio = 1.29; 95% confidence interval = 0.65-2.58).

CONCLUSIONS

The absence of exon 3 of the GHR may be associated with a more morbid acromegalic clinical and biochemical picture and a lower chance of achieving IGF-I normalization after therapy.

Insulin-like growth factor-1 is essential to the increased mortality caused by excess growth hormone: a case of thyroid cancer and non-Hodgkin's lymphoma in a patient with pituitary acromegaly

The effects of growth hormone are mediated in part by stimulating the production of insulin-like growth factor-1. Insulin-like growth factor-1 has significant effects on cell proliferation and differentiation, it is a potent mitogen, and it is a powerful inhibitor of programmed cell death (apoptosis). Insulin-like growth factor-1 also has a well-established role in the transformation of normal cells to malignant cells. Case reports on a possible association between elevated growth hormone and cancer risk in a variety of patient groups have been published. Here, we describe clinical and laboratory findings for a patient with acromegaly who first developed thyroid cancer, and then, in the follow up period, probably due to poorly controlled insulin-like growth factor-1 levels, developed a large cell non-Hodgkin's lymphoma. A search revealed that a case with these peculiarities had not previously been reported.

Pituitary tumors in childhood: update of diagnosis, treatment and molecular genetics

Pituitary tumors are rare in childhood and adolescence, with a reported prevalence of up to one per 1 million children. Only 2-6% of surgically treated pituitary tumors occur in children. Although pituitary tumors in children are almost never malignant and hormonal secretion is rare, these tumors may result in significant morbidity. Tumors within the pituitary fossa are mainly of two types: craniopharyngiomas and adenomas. Craniopharyngiomas cause symptoms by compressing normal pituitary, causing hormonal deficiencies and producing mass effects on surrounding tissues and the brain; adenomas produce a variety of hormonal conditions such as hyperprolactinemia, Cushing disease and acromegaly or gigantism. Little is known about the genetic causes of sporadic lesions, which comprise the majority of pituitary tumors, but in children, more frequently than in adults, pituitary tumors may be a manifestation of genetic conditions such as multiple endocrine neoplasia type 1, Carney complex, familial isolated pituitary adenoma and McCune-Albright syndrome. The study of pituitary tumorigenesis in the context of these genetic syndromes has advanced our knowledge of the molecular basis of pituitary tumors and may lead to new therapeutic developments.