Comparison of octreotide acetate LAR and lanreotide SR in patients with acromegaly

Interpreting growth hormone and IGF-I results using modern assays and reference ranges for the monitoring of treatment effectiveness in acromegaly

Standard treatment for acromegaly focuses on the achievement of target absolute levels of growth hormone (GH) and insulin-like growth factor (IGF-I). The appropriateness of these targets when measured using modern assay methods is not well defined. This paper reviews biochemical status assessed using methods available at the time and associated clinical outcomes. GH measurements were shown to provide an indication of changes in tumor size, and failure of GH suppression after glucose stimulation is associated with tumor recurrence. IGF-I levels were more closely associated with changes in symptoms and signs. Reduced GH and IGF-I concentrations were shown to be associated with increased longevity, although the degree of increase has only been analyzed for GH. Lowering of GH and IGF-I has consistently been associated with improved outcomes; however, absolute levels reported in previous studies were based on results from methods and reference ranges that are now obsolete. Applying previously described absolute thresholds as targets (e.g. "normal" IGF-I level) when using current methods is best applied to those with active acromegaly symptoms who could benefit from further lowering of biochemical markers. In asymptomatic individuals with mild IGF-I or GH elevations, targeting biochemical "normalization" would result in the need for combination pharmacotherapy in many patients without proven benefit. Measurement of both GH and IGF-I remains an essential component of diagnosis and monitoring the effectiveness of treatment in acromegaly; however, treatment goals based only on previously identified absolute thresholds are not appropriate without taking into account the assay and reference ranges being employed. Treatment goals should be individualized considering biochemical improvement from an untreated baseline, symptoms of disease, risks, burdens and costs of complex treatment regimens, comorbidities, and quality of life.

Long-acting microneedle formulations

The minimally-invasive and painless nature of microneedle (MN) application has enabled the technology to obviate many issues with injectable drug delivery. MNs not only administer therapeutics directly into the dermal and ocular space, but they can also control the release profile of the active compound over a desired period. To enable prolonged delivery of payloads, various MN types have been proposed and evaluated, including dissolving MNs, polymeric MNs loaded or coated with nanoparticles, fast-separable MNs hollow MNs, and hydrogel MNs. These intricate yet intelligent delivery platforms provide an attractive approach to decrease side effects and administration frequency, thus offer the potential to increase patient compliance. In this review, MN formulations that are loaded with various therapeutics for long-acting delivery to address the clinical needs of a myriad of diseases are discussed. We also highlight the design aspects, such as polymer selection and MN geometry, in addition to computational and mathematical modeling of MNs that are necessary to help streamline and develop MNs with high translational value and clinical impact. Finally, up-scale manufacturing and regulatory hurdles along with potential avenues that require further research to bring MN technology to the market are carefully considered. It is hoped that this review will provide insight to formulators and clinicians that the judicious selection of materials in tandem with refined design may offer an elegant approach to achieve sustained delivery of payloads through the simple and painless application of a MN patch.

The safety of lanreotide for neuroendocrine tumor

INTRODUCTION

Lanreotide autogel is a synthetic somatostatin analogue which has been FDA and EMA approved for unresectable, well to moderately differentiated, locally advanced or metastatic gastroenteropancreatic neuroendocrine tumor. Its action is mediated by its affinity to somatostatin receptors, especially sst2 and sst5 receptors. Its longer half-life offers the convenience of 4-week dosing over the need for frequent injections of short-acting somatostatin analogues. Areas covered: Lanreotide ATG offers progression-free survival benefit in locally advanced or metastatic neuroendocrine tumor (NET) compared to placebo, reflecting a strong antiproliferative signal. As lanreotide is commonly used for management of NET, it is imperative to recognize and appropriately manage any drug-related toxicities. In this review, we will provide an overview of the toxicity with lanreotide and its management. Expert opinion: Lanreotide is highly effective in managing carcinoid symptoms and has a robust anti-tumor effect in NET. Overall, it is well tolerated with low rates of treatment discontinuation due to toxicity. It's toxicity profile is mostly predictable, and patients should be informed of the transient nature of some of the upfront toxicities.

Cost-effectiveness of somatostatin analogues in the treatment of acromegaly

INTRODUCTION

Somatostatin analogues (SSAs) are the largest contributor to the direct medical cost of acromegaly management worldwide. The aim of this review was to identify and report available evidence on the cost-effectiveness of SSAs in the treatment of acromegaly.

AREAS COVERED

A literature search on relevant papers published up to April 2018 was performed. A total of 22 eligible studies (10 full-text articles and 12 conference abstracts) conducted in 14 countries were included in the analysis. In majority of studies, modelling technique was the principal research method.

EXPERT COMMENTARY

The results of cost-effectiveness analyses: 1) support published recommendations where SSAs are indicated as first-line medical treatment for patients with persistent disease after surgery or who are not eligible for surgery; 2) suggest that preoperative medical therapy with SSAs may be highly cost-effective in acromegalic patients with macroadenoma, in centres without optimal surgical results 3) indicate that in some countries pasireotide and pegvisomant appeared to be cost-effective or even dominant strategies in comparison to first-generation SSAs. The main limitation of economic evaluations was the lack of high-quality studies designed to directly compare various treatment strategies in acromegaly.

Injectable formulations of poly(lactic acid) and its copolymers in clinical use

Poly(lactic acid) and its copolymers have revolutionized the field of drug delivery due to their excellent biocompatibility and tunable physico-chemical properties. These copolymers have served the healthcare sector by contributing many products to combat various diseases and for biomedical applications. This article provides a comprehensive overview of clinically used products of poly(lactic acid) and its copolymers. Multi-dimension information covering product approval, formulation aspects and clinical status is described to provide a panoramic overview of each product. Moreover, leading patented technologies and various clinical trials on these products for different applications are included. This review focuses on marketed injectable formulations of PLA and its copolymers.

New therapeutic agents for acromegaly

The currently available somatostatin receptor ligands (SRLs) and growth hormone (GH) antagonists are used to control levels of GH and insulin-like growth factor 1 (IGF-1) in patients with acromegaly. However, these therapies are limited by wide variations in efficacy, associated adverse effects and the need for frequent injections. A phase III trial of oral octreotide capsules demonstrated that this treatment can safely sustain suppressed levels of GH and IGF-1 and reduce the severity of symptoms in patients with acromegaly previously controlled by injectable SRL therapy, with the added benefit of no injection-site reactions. Phase I and phase II trials of the pan-selective SRL DG3173, the liquid crystal octreotide depot CAM2029 and an antisense oligonucleotide directed against the GH receptor have shown that these agents can be used to achieve biochemical suppression in acromegaly and have favourable safety profiles. This Review outlines the need for new therapeutic agents for patients with acromegaly, reviews clinical trial data of investigational agents and considers how these therapies might best be integrated into clinical practice.

Treatment Factors That Influence Mortality in Acromegaly

Acromegaly is a rare condition characterized by excessive secretion of growth hormone (GH), which is almost always due to a pituitary adenoma. Acromegaly is associated with significant morbidity such as hypertension, type 2 diabetes, cardiomyopathy, obstructive sleep apnoea, malignancy and musculoskeletal abnormalities. Acromegaly has also been associated with increased mortality in several retrospective studies. This review will focus on the epidemiological data relating to mortality rates in acromegaly, the relationship between acromegaly and malignancy, the role of GH and insulin-like growth factor-I in assessing the risk of future mortality, and the impact of radiotherapy and hypopituitarism on mortality.

Estrogen and selective estrogen receptor modulators (SERMs) for the treatment of acromegaly: a meta-analysis of published observational studies

Estrogen and selective estrogen receptor modulator (SERM) treatments for acromegaly have received limited attention since the development of newer pharmacologic therapies. There has been ongoing research evidence suggesting their utility in the biochemical control of acromegaly. Therefore, the aim of this meta-analysis was to synthesise current evidence with a view to determining to what extent and in which acromegalic patient subsets do estrogen and SERMs reduce IGF-1 levels. A literature search was conducted (finished December 2012), which included all studies pertaining to estrogen or SERM treatment and IGF-1. Seven patient subsets were identified from six published observational studies, and were pooled using meta-analytic methods. Overall, the pooled mean loss in IGF-1 was -29.09 nmol/L (95 % CI -37.23 to -20.95). A sensitivity analysis indicated that women receiving estrogen had a substantially greater reduction in IGF-1 levels compared with women receiving SERMs, with a weighted mean loss in IGF-1 of -38.12 nmol/L (95 % CI -46.78 to -29.45) compared with -22.91 nmol/L (95 % CI -32.73 to -13.09). There was a trend that did not reach statistical significance for men receiving SERM treatment at -11.41 nmol/L (95 % CI -30.14 to 7.31). It was concluded that estrogen and SERMs are a low cost and effective treatment to achieve control of IGF-1 levels in acromegalic women either as concomitant treatment for refractory disease, or where access to conventional therapy is restricted. Their use in men requires further study.

Implications of Somatostatin Analogues in the Treatment of Acromegaly

Octreotide has an important role in the medical management of acromegaly. Its place in the management of acromegaly as an adjuvant therapy after neurosurgery is well established with a well-demonstrated efficacy. It can also be used in certain clinical conditions as a neoadjuvant treatment. Clinicians and patients should be aware of the possible side effects of octreotide treatment.

A review of the use of somatostatin analogs in oncology

Somatostatin is a neuropeptide produced by paracrine cells that are located throughout the gastrointestinal tract, lung, and pancreas, and is also found in various locations of the nervous system. It exerts neural control over many physiological functions including inhibition of gastrointestinal endocrine secretion through its receptors. Potent and biologically stable analogs of somatostatin have been developed. These somatostatin analogs show different efficacy on different receptors, and receptors are varyingly concentrated in specific tissues. Antitumor and antisecretory effects of somatostatin analogs in cancer have been shown in several in vivo and in vitro studies. However, these activities have not always yielded into clinically relevant patient outcome benefit. Somatostatin analogs are of clinical benefit in treating symptoms of ectopic hormone secretion (adrenocorticotropic hormone, growth hormone-releasing hormone) in lung cancer, without inducing a significant tumor response. They have also been shown to induce a statistically significant decrease in bone pain and increase in Karnofsky performance status in patients with metastatic prostate cancer. Somatostatin analogs alone or in combination with other agents have only limited antitumoral effect in breast cancer. In gastrointestinal cancers, studies have not shown an objective tumor response to somatostatin analogs except in endocrine tumors of the liver with symptomatic and biochemical improvement. In neuroendocrine tumors of the gastrointestinal system and pancreas, very high symptomatic and biochemical response rates have been achieved with somatostatin analogs. Antiproliferative activity has been clearly shown in metastatic midgut neuroendocrine tumors.

Long-Acting Octreotide and Prolonged-Release Lanreotide Formulations Have Different Pharmacokinetic Profiles

Single-dose pharmacokinetic (PK) profiles and multiple-dose PK modeling were compared for long-acting octreotide (20 or 60 mg) and prolonged-release lanreotide (90 or 120 mg) over 91 days; steady-state profiles were simulated. All treatments were well tolerated. Octreotide 20-mg profile showed increased concentration on day 1, lag from days 2 to 6, then prolonged plateau phase (days 11-41); 60-mg PK was dose proportional. Lanreotide 90-mg profile showed C(max) on day 1 then elimination (apparent t1/2 25.5 days); 120-mg profile was underproportional. Steady-state PK of octreotide 20 mg/28 d suggested a C(mean) of 1216 rhog/mL (range, 1065-1585) with low fluctuation index (43%). Steady-state PK of lanreotide 90 mg/28 d suggested a C(mean) of 4455 rhog/mL (range, 2499-9279) with high fluctuation index (152%). Long-acting octreotide had more predictable PK than prolonged-release lanreotide. Simulated steady-state profiles suggest long-acting octreotide could be optimized to meet individual patient needs. In contrast, prolonged-release lanreotide requires exposure constantly above the therapeutic target to enable monthly long-term therapy.

Management options for persistent postoperative acromegaly

This article presents management options for the patient with acromegaly after noncurative surgery. The current evidence for repeat surgery, adjuvant medical therapy with somatostatin analogues, dopamine agonists, the growth hormone receptor antagonist pegvisomant, combination medical therapy, and radiotherapy in the context of persistent postoperative disease are summarized. The relative advantages and disadvantages of each of these treatment modalities are explored, and a general treatment algorithm that integrates these modalities is proposed.

Somatostatin analogs as a first-line treatment in acromegaly: when is it appropriate?

PURPOSE OF REVIEW

To discuss the role of medical therapy of acromegaly as a first-line treatment, focusing on recent data on the use of somatostatin analogs (SSAs), the first-choice pharmacotherapy for treating acromegaly.

RECENT FINDINGS

Despite pituitary surgery and radiotherapy, a significant number of patients with acromegaly needed adjuvant medical therapy, and primary medical therapy nowadays is increasingly considered. According to a recent consensus statement on the management of acromegaly, primary pharmacological therapy with SSAs may be indicated in patients who are otherwise poor surgical candidates or refuse surgery, and in those in whom there is a low probability of a surgical cure. The long-acting SSAs have been found to be effective in improving symptoms and signs of acromegaly in a high percentage of patients and induce normalization of growth hormone and insulin-like growth factor-I levels approximately in 60-80% of patients, respectively. Evidence has suggested that SSAs induce a clinically significant tumor shrinkage when given as first-line, when this reduction of tumor volume could be helpful in improving the outcome of subsequent surgery or improving the clinical syndrome in patients with unacceptable surgical risk, whereas the tumor shrinkage was seen less frequently when the drug was used after surgical resection and/or radiotherapy.

SUMMARY

Pharmacological management plays a pivotal role in the treatment of acromegaly, and first-line medical therapy with SSAs is being widely used in clinical practice, either prior to surgery or in patients who are otherwise poor surgical candidates and in those in whom there is a low probability of a surgical cure.

Comparative effectiveness review of treatment options for pituitary microadenomas in acromegaly

OBJECT

Acromegaly, a syndrome of excess growth hormone (GH) secretion typically caused by a GH-secreting pituitary adenoma, reduces life expectancy by approximately 10 years when left untreated. Treatment of acromegaly involves combinations of one or more discrete therapeutic modalities to achieve biochemical control. Unfortunately, data capable of informing decisions among alternate management strategies are presently lacking.

METHODS

The authors performed a comparative effectiveness research (CER) review integrating efficacy, cost, and quality of life (QOL) analysis for treatment strategies comprising various combinations of surgery, radiotherapy, stereotactic radiosurgery, and pharmacotherapy in patients with acromegaly caused by a pituitary microadenoma. A management decision tree was used to identify 5 treatment strategies, each with up to 4 potential treatment steps. Efficacy was assessed using recent literature reports of biochemical control rates for each modality. Cost estimations were derived from wholesale drug prices and from the Healthcare Cost and Utility Project. Quality of life data were obtained from studies utilizing the Acromegaly Quality of Life Questionnaire.

RESULTS

Individual treatment modalities were analyzed and ranked in each of 3 domains: highest rate of success, lowest cost, and highest QOL, and these scores were combined to facilitate comparison of overall effectiveness of each of the management strategies. These aggregate effectiveness scores were used to compare the 5 strategies from the decision tree, and a novel strategy was also proposed.

CONCLUSIONS

The choice of management strategy must be individualized for each patient with acromegaly. This CER analysis provides a comprehensive framework to inform clinical decisions among alternate management strategies in patients with GH-secreting pituitary microadenomas.

Safety review: dose optimization of somatostatin analogs in patients with acromegaly and neuroendocrine tumors

INTRODUCTION

Patients with either acromegaly or neuroendocrine tumors (NET) can be treated with somatostatin analogs to relieve symptoms and improve disease control. However, there is an absence of large clinical trials specifically designed to document the safety when increases in somatostatin analog dosing are needed in patients who do not achieve their treatment goals. To fully explore and communicate any potential risks, we conducted a literature review and present a summary of the studies documenting the safety and tolerability of dose optimization with somatostatin analogs in patients with acromegaly and NET.

METHODS

A literature search was undertaken to find clinical studies specifically reporting the effects of dose titration using the depot formulations of the somatostatin analogs, octreotide long-acting repeatable (LAR) or lanreotide, in patients with acromegaly and NET.

RESULTS

Publications that described the treatment and management of patients with acromegaly and NET were reviewed. The rationale for dose optimization, including high-dose treatment in patients who are inadequately controlled on conventional doses and the safety and tolerability of somatostatin analogs, is discussed.

CONCLUSION

A review of published clinical studies demonstrates that dose optimization provides additional biochemical control in patients with acromegaly and NET who are inadequately controlled with conventional starting doses of octreotide LAR and lanreotide ATG. The benefits of dose optimization include improved efficacy without a significant change in the recorded adverse events and the tolerability of the treatment. Therefore, patient response to treatment should be routinely monitored and their somatostatin analog dose increased or decreased thereafter according to their individual response.

Medical therapy in acromegaly

Acromegaly is a rare disease characterized by excess secretion of growth hormone (GH) and increased circulating insulin-like growth factor 1 (IGF-1) concentrations. The disease is associated with increased morbidity and premature mortality, but these effects can be reduced if GH levels are decreased to <2.5 μg/l and IGF-1 levels are normalized. Therapy for acromegaly is targeted at decreasing GH and IGF-1 levels, ameliorating patients' symptoms and decreasing any local compressive effects of the pituitary adenoma. The therapeutic options for acromegaly include surgery, radiotherapy and medical therapies, such as dopamine agonists, somatostatin receptor ligands and the GH receptor antagonist pegvisomant. Medical therapy is currently most widely used as secondary treatment for persistent or recurrent acromegaly following noncurative surgery, although it is increasingly used as primary therapy. This Review provides an overview of current and future pharmacological therapies for patients with acromegaly.

Octreotide long-acting release (LAR): a review of its use in the management of acromegaly

Octreotide long-acting release (LAR) [Sandostatin LAR] is a somatostatin analogue with a well established clinical profile in patients with acromegaly. It binds to somatostatin receptor subtypes 2 and 5 with high potency to reduce the production and secretion of growth hormone (GH) and insulin-like growth factor (IGF)-I. Octreotide LAR is administered intramuscularly once every 28 days, in contrast to the subcutaneous formulation which requires administration two to three times daily. In several noncomparative trials, octreotide LAR was effective as primary therapy in normalizing GH and IGF-I levels and reducing tumour volume in patients with acromegaly. In addition, no significant difference was seen between octreotide LAR and surgery or lanreotide long-acting (LA) or lanreotide Autogel(R) (ATG) in small, randomized or observational, primary therapy trials. In another small, randomized trial, preoperative octreotide LAR followed by surgery was no more effective than surgery alone in terms of normalizing IGF-I levels, except in patients with macroadenoma. Octreotide LAR has also demonstrated good efficacy as postoperative adjuvant therapy, alone or in combination with pegvisomant, in randomized or noncomparative trials. In patients with different treatment histories (mixed populations), the efficacy of octreotide LAR appears to be generally similar to that of lanreotide ATG and greater than that of lanreotide LA, according to data from switching or crossover studies. Also in mixed populations, the efficacy of octreotide LAR was not significantly different to that of pegvisomant in terms of normalizing IGF-I levels in a randomized trial, and octreotide LAR demonstrated good efficacy in combination with cabergoline in a small, sequential-treatment trial. Octreotide LAR was generally well tolerated in clinical trials, with the most commonly occurring adverse events being gastrointestinal or hepatobiliary in nature. Thus, octreotide LAR continues to be a valuable option in the treatment of acromegaly.

Medical therapy of acromegaly: efficacy and safety of somatostatin analogues

Acromegaly is a chronic disease with signs and symptoms due to growth hormone (GH) excess. The most frequent cause of acromegaly is a GH-producing pituitary adenoma. Chronic GH excess is accompanied by long-term complications of the locomotor (arthrosis) and cardiovascular (atherosclerosis, cardiomyopathy) systems and is, when untreated, associated with an increased mortality. The aim of treatment of acromegaly is to improve symptoms, to achieve local tumour mass control, and to decrease morbidity and mortality. Treatment options include surgery, medical therapy and radiotherapy. Transsphenoidal surgery is the first choice of treatment when a definitive cure can be achieved, particularly in the case of microadenomas and when decompression of surrounding structures (optic chiasm, ophthalmic motor nerves) is indicated. Primary medical therapy has been increasingly applied in recent years, especially when a priori chances of surgical cure are low (because of adenoma size and localization) and in patients with advanced age and/or serious co-morbidity. In addition, preoperative primary medical therapy may result in tumour shrinkage, facilitating tumour resection, and may reduce perioperative complications due to GH excess. Within the spectrum of medical therapy, long-acting somatostatin analogues (somatostatins) are considered as first-line treatment. Treatment with somatostatin analogues results in GH control in approximately 60% of patients. In addition, somatostatin analogues induce tumour shrinkage in 30-50% of patients, particularly when applied as primary therapy. Prolonged treatment with somatostatin analogues appears to be safe and is usually well tolerated. The currently available somatostatin analogues, octreotide and lanreotide, seem to be equally effective; however, this should still be evaluated in prospective, randomized trials evaluating efficacy with respect to GH control and tumour shrinkage. In patients with an insufficient clinical and biochemical response to somatostatin analogues, combination therapy with dopamine receptor agonists or the GH receptor antagonist pegvisomant usually leads to disease control. New developments in the medical therapy of acromegaly include the universal somatostatin receptor agonist pasireotide, which has a broader affinity for all somatostatin receptor (sst) subtypes compared with the currently available somatostatin analogues with preferential affinity for the sst2 receptor, and chimeric compounds that interact with both somatostatin and dopamine receptors with synergizing effects on GH secretion.

Pituitary tumours: acromegaly

Excessive production of the growth hormone (GH) is responsible for acromegaly. It is related to a pituitary GH-secreting adenoma in most cases. Prevalence is estimated 40-130 per million inhabitants. It is characterised by slowly progressive acquired somatic disfigurement (mainly involving the face and extremities) and systemic manifestations. The rheumatologic, cardiovascular, respiratory and metabolic consequences determine its prognosis. The diagnosis is confirmed by an increased serum GH concentration, unsuppressible by an oral glucose load and by detection of increased levels of insulin-like growth factor-I (IGF-I). Treatment is aimed at correcting (or preventing) tumour compression by excising the disease-causing lesion, and at reducing GH and IGF-I levels to normal values. When surgery, the usual first-line treatment, fails to correct GH/IGF-I hypersecretion, medical treatment with somatostatin analogues and/or radiotherapy can be used. The GH-receptor antagonist (pegvisomant) is helpful in patients who are resistant to somatostatin analogues. Thanks to this multistep therapeutic strategy, adequate hormonal disease control is achieved in most cases, allowing a normal life expectancy.

The effect of acute application of pegvisomant alone and in combination with octreotide on endogenous GH levels during a 6-h test in patients with acromegaly on constant pegvisomant treatment

OBJECTIVE

Co-treatment with somatostatin analogues and growth hormone receptor antagonists in acromegaly might be a new treatment option abolishing the negative effects of monotherapy. Nevertheless, little is known about the acute effect of the combined treatment on endogenous GH and pegvisomant levels.

DESIGN

Ten acromegalic patients on constant pegvisomant therapy were included. Two 6-h GH secretion profiles were performed once after pegvisomant alone (P), the other after an additional 100 microg octreotide sc injection (PO). After 180 min, all patients received a standardized light mixed meal. Endogenous serum GH and pegvisomant levels were measured by special in-house assays. In addition, insulin and glucose were measured.

RESULTS

In the combined profile PO, a significant decrease of median endogenous GH was seen (p<0.01, median percentage decline 75.2%, range 23.7-88.2), which was not seen in profile P. Seven of 10 patients had a decline >70% and might be seen as responders. After meal, endogenous GH significantly decreased only in profile P (p<0.01). Pegvisomant levels did not differ significantly between profiles and did not change significantly during the tests. After meal, glucose levels rose higher and later and insulin levels lower and later in profile PO than in profile P.

CONCLUSION

During pegvisomant treatment, endogenous GH can be reduced significantly by acute application of a somatostatin analogue. Therefore, in acromegalic patients on pegvisomant therapy GH regulation due to somatostatin analogues seems to be preserved.

Efficacy of long-term lanreotide treatment in patients with acromegaly

We investigated the effectiveness of lanreotide for the treatment of active acromegaly in a retrospectively multicenter case series including 53 patients (24 male, 29 female; mean age at diagnosis, 49.5 +/- 13.9 years) with acromegaly treated with lanreotide in nine different centers. Mean tumor diameter was 20 +/- 13 mm; mean basal levels of growth hormone (GH) and insulin-like growth factor I (IGF-I) were 21.3 +/- 26.3 and 579 +/- 177 mug/l, respectively. The primary mode of treatment was surgery in 70% of patients. Twenty-nine patients received only lanreotide (Prolonged Release, Autogel), whereas 24 subjects were also treated with octreotide at another treatment stage. Primary therapy with lanreotide was administered in five patients. Maximal monthly dose of lanreotide Autogel (n = 44) was 60 mg in 45%, 90 mg in 26%, 120 mg in 21% and 180 mg in 8%. During 36 months of lanreotide treatment, mean IGF-I levels decreased from 443 +/- 238 to 276 +/- 147 mug/l (P < 0.001), and mean GH levels, from 5.2 +/- 6.4 to 3.2 +/- 3.0 mug/l (P < 0.001). IGF-I levels normalized in 51% of patients and decreased by >50% towards normal in 32%; the normalization rate was higher in women (65%) than men (33%, P = 0.04). Safe random GH levels (</=2 mug/l) were achieved in 49% of patients. Both IGF-I normalization and safe GH levels were reached in 32% of the cohort. Lanreotide is an effective treatment for active acromegaly. Female sex was associated with higher rates of IGF-I normalization.

Octreotide-LAR vs lanreotide-SR as first-line therapy for acromegaly: a retrospective, comparative, head-to-head study

No head-to-head comparisons are available to analyze the efficacy of octreotide (LAR) and lanreotide (LAN) as first-line treatment of acromegaly.We compared the efficacy of these two drugs in 54 newly diagnosed patients (21 women, 33 men), 27 treated with LAR (10-30 mg every 28 days) and 27 with LAN (60-90 mg/28 days), for 12 months. Each LAR-treated patient was matched with one LAN-treated patient as for GH levels, sex, and age (+/-5 yr). Outcome measures were GH and IGF-I levels and tumor shrinkage and secondarily classical cardiovascular risk factors (total/HDL-cholesterol ratio, glucose tolerance), blood pressure and drug tolerability. In LAR- and in LAN-treated patients, respectively: GH and IGF-I were controlled in 21 (77.7%) and in 16 patients (59.3%; p=0.26); tumor shrinkage was absent (<25%) in 4 and 5 patients (p=1), mild (25.1-50%) in 9 and 12 (p=0.57), moderate (50.1-75%) in 10 and 6 (p=0.37) and notable (>75%) in 4 and 4 patients (p=1). The total/HDL-cholesterol ratio and insulin levels significantly decreased while glucose levels significantly increased in both groups. None of the patients with normal glucose tolerance at diagnosis developed diabetes mellitus. Side effects were mostly at the gastrointestinal level and were similar with both drugs. In conclusion, newly diagnosed patients with acromegaly treated with LAR and LAN have no significantly different prevalence of disease control, tumor shrinkage, improvement of cardiovascular risk markers and side effects. Therefore, both drugs can be safely employed as first-line therapy of acromegaly.

[New medical treatments in pituitary adenomas]

Currently, the role of dopaminergic and somatostatinergic agonists in the treatment of pituitary adenomas is quite well established. Nevertheless, a clearer understanding of the expression of dopaminergic and somatostatinergic receptors at the cellular level of pituitary adenomas as well as the development of newer analogues compounds may drastically change current therapeutic modalities. In particular, the emphasis on the co-expression of different receptors types or subtypes in adenomatous cells highlights functional interactions between receptors leading to an increase in their activity. Newer molecules are also in the process of development : new somatostatin analogues with more universal binding properties to different receptors subtypes, as well as chimeric molecules capable of binding to somatostatinergic and dopaminergic receptors. In the midst of GH-secreting pituitary adenomas, a positive correlation exists between the expression of Sst2 mRNA and the inhibition of GH release by somatostatin analogues. The involvement of Sst5 subtype in adenomas resistant to preferential Sst2 agonists has recently been proved. Another recently developed compound has a more universal Sst binding profile. This compound, named SOM-230, has a 25, 5 and 40 times higher binding affinity to Sst1, Sst3 and Sst5 receptors respectively, and 2,5 times lower affinity to Sst2, when compared to octreotide. SOM-230 could therefore allow for much more effective methods in treating patients suffering from acromegaly. Besides, the use of a chimeric molecule presenting a binding affinity to both Sst2 and D2 subtypes (BIM-23A287) inhibits the secretion of GH in ways similar to the Sst2 or D2 agonists used alone or concurrently but however in a concentration 50 times lower than that of the latter. The discovery of Sst5 and D2 subtypes at the level of corticotropic adenomas reveals newer therapeutic perspectives with promising preliminary results with the use of SOM-230 ; these finding lead to a rise in interest in cabergoline. In the midst of non-functioning pituitary adenomas, the expression of Sst2, Sst3 and D2 receptors will perhaps allow the use of combined therapies associating the new somatostatin analogues to the dopaminergic agonists or even use dopastatin (BIM-23A760, chimeric molecule Sst2-Sst5-D2). The preliminary results obtained in vitro with this molecule are actually encouraging since they show a dose dependent inhibition of the cellular replication mechanisms in 60 % of the cases. Finally, concerning prolactinomas the discovery of Sst5 receptors lead to consider the use of somatostatinergic agonists specific to the Sst5 receptor, SOM-230 in particular. Nevertheless, it seems that adenomas resistant to dopaminergic agonist due to a lack of expression of D2 receptor fail to express Sst5 receptors as well. On the other hand, dopastatin appears to be more efficient than cabergoline in the management of this type of adenomas. Therefore, the growing awareness concerning the mechanisms involved in the control of pituitary secretions as well as cellular proliferation will perhaps allow physicians to treat the pathology of pituitary adenomas, macroadenomas in particular, using solely pharmacological means instead of invasive surgical procedures and/or radiotherapy.

Therapeutic options in the management of acromegaly: focus on lanreotide Autogel

BACKGROUND

In acromegaly, expert surgery is curative in only about 60% of patients. Postoperative radiation therapy is associated with a high incidence of hypopituitarism and its effect on growth hormone (GH) production is slow, so that adjuvant medical treatment becomes of importance in the management of many patients.

OBJECTIVE

To delineate the role of lanreotide in the treatment of acromegaly.

METHODS

Search of Medline, Embase, and Web of Science databases for clinical studies of lanreotide in acromegaly.

RESULTS

Treatment with lanreotide slow release and lanreotide Autogel((R)) normalized GH and insulin-like growth factor-I (IGF-I) concentrations in about 50% of patients. The efficacy of 120 mg lanreotide Autogel((R)) on GH and IGF-I levels was comparable with that of 20 mg octreotide LAR. There were no differences in improvement of cardiac function, decrease in pancreatic beta-cell function, or occurrence of side effects, including cholelithiasis, between octreotide LAR and lanreotide Autogel(R). When postoperative treatment with somatostatin analogs does not result in normalization of serum IGF-I and GH levels after noncurative surgery, pegvisomant alone or in combination with somatostatin analogs can control these levels in a substantial number of patients.

Guidelines for the treatment of growth hormone excess and growth hormone deficiency in adults

The V Consensus Group Meeting on 'Guidelines for Treatment of GH Excess and GH Deficiency in the Adult' was an international workshop held on February 20-22, 2006 in Santa Monica, California, USA. The principal aim of this meeting was to provide guidelines for the evaluation and treatment of adults with either form of abnormal GH secretion: GH excess or GH deficiency. The workshop included debates as to the choice of primary treatment, discussions of the targets for adequate treatment, and concluded with presentations on open issues germane to adult GH treatment including the role of GH in malignancies, the impact of longterm treatment on bone, and a cost-benefit analysis. The meeting was comprised of 66 delegates representing 13 different countries.

A critical analysis of clinically available somatostatin analog formulations for therapy of acromegaly

CONTEXT

Short and long-acting somatostatin (SRIF) analogs are approved for clinical use in acromegaly. Recent analysis of the relative efficacy of octreotide LAR and lanreotide SR on the GH-IGF-I axis in acromegaly favored octreotide LAR in the secondary treatment of patients not preselected by SRIF responsiveness. A novel aqueous formulation of lanreotide, lanreotide Autogel (ATG), has recently been approved and is the predominant (and only in the United States) formulation of lanreotide used clinically.

OBJECTIVE

We performed a critical review of SRIF analog treatment to establish the relative efficacy of three clinically available SRIF analog preparations, octreotide LAR, lanreotide SR, and lanreotide ATG (Somatuline depot in the United States) in control of the GH-IGF-I axis in acromegaly.

DATA SOURCES

Data were drawn from MEDLINE and the bibliography of analyses of long-acting SRIF analogs.

DATA COLLECTION

We reviewed the largest studies of sc octreotide, octreotide LAR, and lanreotide SR, all that included biochemical end-point data for lanreotide ATG, and studies that directly compared the efficacy of octreotide LAR and lanreotide SR.

DATA SYNTHESIS

Caveats considered included differences in baseline GH and IGF-I values, patient selection, and interassay and intraassay variability, confounding the analysis. Studies comparing patients treated contiguously with lanreotide SR and octreotide LAR are fraught with methodological problems, however, are suggestive of marginally greater efficacy in control of the GH-IGF-I axis for octreotide LAR. Lanreotide ATG shows noninferiority to lanreotide SR. Five small studies directly comparing octreotide LAR and lanreotide ATG suggest no significant differences between these preparations in control of biochemical end-points.

CONCLUSION

Lanreotide ATG and octreotide LAR are equivalent in the control of symptoms and biochemical markers in patients with acromegaly.

Ghrelin in pathological conditions

The recently identified gastric hormone ghrelin was initially described as a natural Growth Hormone Secretagogue Receptor ligand. Apart from ghrelin's first discovered action, which was the stimulation of Growth Hormone release, implications for many other functions have been reported. It seems that ghrelin exhibits an important role in conditions related to processes regulating nutrition, body composition and growth, as well as heart, liver, thyroid or kidney dysfunction. In this review, current available knowledge about ghrelin's role in various pathological conditions is presented.

Acromegaly

Acromegaly is an acquired disorder related to excessive production of growth hormone (GH) and characterized by progressive somatic disfigurement (mainly involving the face and extremities) and systemic manifestations. The prevalence is estimated at 1:140,000-250,000. It is most often diagnosed in middle-aged adults (average age 40 years, men and women equally affected). Due to insidious onset and slow progression, acromegaly is often diagnosed four to more than ten years after its onset. The main clinical features are broadened extremities (hands and feet), widened thickened and stubby fingers, and thickened soft tissue. The facial aspect is characteristic and includes a widened and thickened nose, prominent cheekbones, forehead bulges, thick lips and marked facial lines. The forehead and overlying skin is thickened, sometimes leading to frontal bossing. There is a tendency towards mandibular overgrowth with prognathism, maxillary widening, tooth separation and jaw malocclusion. The disease also has rheumatologic, cardiovascular, respiratory and metabolic consequences which determine its prognosis. In the majority of cases, acromegaly is related to a pituitary adenoma, either purely GH-secreting (60%) or mixed. In very rare cases, acromegaly is due to ectopic secretion of growth-hormone-releasing hormone (GHRH) responsible for pituitary hyperplasia. The clinical diagnosis is confirmed biochemically by an increased serum GH concentration following an oral glucose tolerance test (OGTT) and by detection of increased levels of insulin-like growth factor-I (IGF-I). Assessment of tumor volume and extension is based on imaging studies. Echocardiography and sleep apnea testing are used to determine the clinical impact of acromegaly. Treatment is aimed at correcting (or preventing) tumor compression by excising the disease-causing lesion, and at reducing GH and IGF-I levels to normal values. Transsphenoidal surgery is often the first-line treatment. When surgery fails to correct GH/IGF-I hypersecretion, medical treatment with somatostatin analogs and/or radiotherapy can be used. The GH antagonist (pegvisomant) is used in patients that are resistant to somatostatin analogs. Adequate hormonal disease control is achieved in most cases, allowing a life expectancy similar to that of the general population. However, even if patients are cured or well-controlled, sequelae (joint pain, deformities and altered quality of life) often remain.

Somatostatin agonists for treatment of acromegaly

The discovery of somatotropin-release inhibitory factor (SRIF) in hypothalamic extract in 1970 led to the synthesis of the first somatostatin analog octreotide, discovery of five somatostatin receptor subtypes, and development of additional somatostatin receptor ligands (SRL) as pharmacotherapy for acromegaly and other neuroendocrine tumors. Long-acting formulations of SRL (octreotide LAR Depot, lanreotide SR and lanreotide autogel) assure improved patient compliance with weekly up to monthly injections, and are commonly used as primary or adjuvant treatment of acromegaly. We review SRL currently available, emphasizing long-acting compounds and their efficacy in controlling acromegaly. Disease control is evaluated by biochemical markers, tumor shrinkage, and disease-symptom improvement balanced against drug-related side effects.

Medical therapy: options and uses

Since the initial use of medical treatment for acromegaly, several advances have been made in the understanding of the pathophysiology of growth hormone producing tumors, resulting in the development of multiple medical options and novel treatments. Currently there are three major classes of medication available for the treatment of acromegaly: somatostatin receptor ligands, growth hormone receptor antagonists, and dopamine agonists. Somatostatin receptor ligands are the treatment of choice for acromegaly due to their effectiveness in controlling growth hormone excess in approximately 60% of patients and their beneficial effects on tumor volume. Clinical trials have demonstrated efficacy of pegvisomant in up to 97% of patients, but long term data and safety have yet to be established. Dopamine agonists are inexpensive, but their use is hampered by their lack of efficacy compared to other medications. Medical therapy has an established role as adjuvant therapy after non-curative surgery, as well as primary therapy for selected patients unsuitable for surgical resection. Medical treatment to control growth hormone hypersecretion is often needed after radiation therapy until the effects are evident. Preliminary data suggest a potential role for medical treatment prior to surgical resection, surgical debulking to improve medical efficacy, and combination therapy with multiple medications from the three classes. More studies are required, however, to validate the utility of these approaches in treating acromegaly. With the available therapies, disease control can be achieved in nearly all patients with acromegaly.

Acromegaly

Acromegaly is caused by growth hormone hypersecretion, mostly from a pituitary adenoma, driving insulin-like growth factor 1 overproduction. Manifestations include skeletal and soft tissue growth and deformities; and cardiac, respiratory, neuromuscular, endocrine, and metabolic complications. Increased morbidity and mortality require early and tight disease control. Surgery is the treatment of choice for microadenomas and well-defined intrasellar macroadenomas. Complete resection of large and invasive macroadenomas rarely is achieved; hence, their low rate of disease remission. Pharmacologic treatments, including long-acting somatostatin analogs, dopamine agonists, and growth hormone receptor antagonists, have assumed more importance in achieving biochemical and symptomatic disease control.

Beneficial effect of dose escalation of octreotide-LAR as first-line therapy in patients with acromegaly

OBJECTIVE

To evaluate the efficacy of dose escalation of Octreotide-long-acting repeatable (LAR) up to 40 mg/month we studied 56 newly diagnosed patients with acromegaly (24 women, 32 men; age 20-82 years).

DESIGN

Analytical, observational, open and prospective.

METHODS

Three months after LAR treatment beginning with a dose of 20 mg /q28d (every 28 days), 24 patients maintained the same dose (Group A), while 32 required a dose of 30 mg/q28d (Group B). The dose was further increased to 40 mg/q28d in 17 out of the 32 patients of Group B for another 12 months (Group C).

RESULTS

After 24 months, serum GH and IGF-I levels decreased by 93.1 +/- 8.6% (95% confidence limit (CL) 90.8-95.4%) and 62.7 +/- 13.4% (95% CL 59.1-66.3%) respectively. Control of GH and IGF-I levels was achieved in 45 patients (80.3%). Tumor shrinkage after 12 months was 49.8 +/- 23%; the relative tumor shrinkage during the second 12 months of treatment was 35.3 +/- 13.1% and overall tumor volume was 68.1 +/- 16.5% (95% CL 63.7-72.5%). Glucose tolerance impaired in eight patients (14.3%): four in Group A and four in Group C (16.7% vs 36.4%, P=0.39). The final dose was predicted by the patient's age at diagnosis (t=-2.2; P=0.032) and baseline tumor volume (t=2.1; P=0.043).

CONCLUSION

An increase of the LAR dose up to 40 mg/q28d in patients resistant to 30 mg/q28d is followed by greater suppression of GH and IGF-I levels and tumor shrinkage without further significant impairment of glucose tolerance when compared with lower doses. These results suggest that a new dosage schedule of 40 mg every 28 days is applied in patients with acromegaly mostly of young age and with bigger tumors who are likely to be poorly responsive to standard doses of Octreotide-LAR.

Octreotide therapy in dumping syndrome: Analysis of long-term results

BACKGROUND

Octreotide therapy is effective in controlling severe dumping symptoms during short-term follow-up but little is known about long-term results.

AIM

To report on the long-term results of patients with severe dumping syndrome treated at the Leiden University Medical Center with subcutaneous or depot intramuscular (long-acting release) octreotide.

METHODS

Follow-up of 34 patients with severe dumping syndrome refractory to other therapeutic measures treated between 1987 and 2005 with octreotide subcutaneous/long-acting release. At regular intervals symptoms, quality of life, weight, faecal fat excretion and gallstone formation were evaluated.

RESULTS

All patients had excellent initial relief of symptoms during octreotide subcutaneous therapy. However, during follow-up 16 patients stopped therapy because of side effects (n = 9) or loss of efficacy (n = 7). Four patients died. Fourteen patients (41%) remain using octreotide (follow-up 93 +/- 15 months), seven are on octreotide subcutaneous and seven on octreotide long-acting release. Patients with severe dumping (both early and late) do better on subcutaneous than long-acting release despite the inconvenience of frequent injections. Dumping symptoms are reduced by 50% even in long-term users. Body weight continues to increase during therapy despite more pronounced steatorrhoea.

CONCLUSION

The long-term the efficacy of octreotide is much less favourable compared with short-term treatment.

Growth hormone receptor antagonists

The currently available long-acting somatostatin analogs normalize serum growth hormone (GH) levels and insulin-like growth factor-I levels in approximately 60% of patients with acromegaly. The recently introduced GH receptor antagonist, pegvisomant, is able to normalize insulin-like growth factor-I levels in virtually all acromegalic subjects. Although no correlation between increased GH concentrations and tumor size has been found, long-term safety studies are still in progress. Also, pegvisomant monotherapy is administered once daily and is very costly. Combined treatment of a somatostatin analog with pegvisomant appears to be an effective and rational approach.

Medical treatment of acromegaly: comorbidities and their reversibility by somatostatin analogs

Relief of symptoms can be achieved following surgery for growth hormone (GH)-secreting adenomas, as well as after pharmacological therapy with somatostatin analogs. Recently, long-acting somatostatin analog depot formulations, octreotide LAR and lanreotide SR have become available. Somatostatin analogs control GH/insulin-like growth factor (IGF)-1 excess, induce tumor shrinkage in a high proportion of patients, improve symptoms of acromegaly with relatively limited side effects and are successfully administered in patients not suitable for surgery. Furthermore, preoperative somatostatin analogs have been suggested to improve outcome for tumors with limited invasiveness, while surgical tumor debulking in cases that are, at least partially, somatostatin resistant, increases the achievement of normal IGF-1 levels by postoperative somatostatin analog treatment. Effective control of hypertension, as well as diabetes, is mandatory in order to reduce the increased vascular morbidity/mortality. Control of GH/IGF-1 excess generally improves glucose metabolism. Somatostatin analogs improve insulin sensitivity, exerting, however, a concomitant direct inhibitory effect on insulin secretion, with a net balance leaning towards a deterioration in glucose homeostasis. As a result, oral insulin secretagogues (and/or insulin) should probably be preferred to insulin sensitizers in acromegalic patients developing diabetes while on somatostatin analogs. Nevertheless, glucose tolerance remains normal in most of the nondiabetic acromegalic patients, while diabetic acromegalic patients on insulin are at risk for hypoglycemia during initiation of somatostatin analog therapy. Although successful management of acromegaly has been associated with improvement in morphological and functional parameters of cardiomyopathy, limited and conflicting information is available regarding the effect on blood pressure control. Contradictory results have also been reported regarding sleep hypopnea or apnea in treated acromegalic patients. As acromegalic skeletal abnormalities are rather irreversible, apneic episodes may persist after normalization of hormonal levels. Aggressive therapy, including surgery, pharmacological treatment and, in some cases, pituitary irradiation, aiming at normalization of IGF-1 levels, is required for arthropathy management. Some improvement in pain, crepitus and range of motion has been observed after treatment with somatostatin analogs. Information on the impact of disease control, either by surgery or somatostatin analog treatment, on gonadal function is limited. Finally, the link between the hormonal/biochemical and the psychiatric/psychological features of acromegaly, as well as a potential basis for positive effects of somatostatin analog therapy remain unclear.

Persistent diastolic dysfunction despite successful long-term octreotide treatment in acromegaly

INTRODUCTION

This study was designed to evaluate potential reversibility of left-ventricular (LV) dysfunction in patients with acromegaly following long-term control of disease. It is unknown whether the cardiac changes induced by acromegaly can be reversed completely by long-term strict control of growth hormone excess by octreotide.

PATIENTS AND METHODS

We compared LV systolic and diastolic function in inactive patients with acromegaly (n = 22), who were divided into patients with long-term control by octreotide (n = 14) and patients with long-term cure by surgery/radiotherapy (n = 8). We also assessed these parameters in patients with active acromegaly (n = 17).

RESULTS

In patients with active acromegaly, systolic function at rest was decreased by 18% (P < 0.01), LV mass index increased by 40% (P < 0.04) and isovolumetric relaxation time increased by 19% (P < 0.01), compared with patients with inactive acromegaly. These parameters were not different between well-controlled and cured patients. Using tissue Doppler imaging, the ratio between early and late diastolic velocity (E'/A' ratio) was decreased in active, compared with inactive acromegaly (0.75+/-0.07 versus 1.24+/-0.15; P < 0.01). This E'/A' ratio was considerably higher in cured, compared with octreotide-treated, patients (1.75+/-0.41 versus 1.05+/-0.1; P < 0.01).

CONCLUSION

Diastolic function is persistently and significantly more impaired in acromegalic patients with long-term control by octreotide than in surgically cured patients, which points to biological effects of subtle abnormalities in growth hormone secretion. Criteria for strict biochemical control of acromegaly should thus be reconsidered.

The somatostatin analogue SOM230, compared with octreotide, induces differential effects in several metabolic pathways in acromegalic patients

OBJECTIVE

Recently, our first clinical study with the novel multiligand somatostatin (SRIF) analogue SOM230 in acromegalic patients showed that SOM230, due to its beneficial inhibitory effects on GH levels compared with octreotide (OCT), might increase the number of patients that can be biochemically controlled. Since SRIF analogues are also known to interact with other metabolic pathways, IGF-I, IGFBP-1, glucose and insulin concentrations on the control day (CD) and on treatment days following a single s.c. injection SOM230 100 and 250 microg, were compared to those following OCT 100 microg.

DESIGN AND PATIENTS

Randomized, cross-over, double-blinded proof-of-concept trial in 12 patients with active acromegaly.

RESULTS

Free IGF-I levels were suppressed after 24 h by OCT, SOM230 250 and 100 microg, whereas at 48 h only both SOM230 dosages still induced these inhibitory effects. Circulating IGFBP-1 levels (AUC; 0830-1430 h) compared with CD, increased sharply after OCT (from 48 to 237 microg/l/h; P < 0.001 vs. CD), while SOM230 250 and 100 microg elicited a lower and dose-dependent effect (163 and 90 microg/l/h, respectively, P < 0.05 vs. CD and OCT). Neither insulin nor GH levels showed statistically significant correlation with IGFBP-1 levels either after SOM230 or OCT. An early rise in glucose levels 1 h postinjection with SOM230 250 microg compared with OCT and CD was observed 8.3 +/- 0.8, 4.4 +/- 0.5 and 4.9 +/- 0.4 mmol/l, respectively: P < 0.05). SOM230 250 microg (19 +/- 4 vs. 46 +/- 3 mU/l on CD: P < 0.05), although clearly less potent than OCT (5.4 +/- 0.4 mU/l: P < 0.01 vs. CD), inhibited insulin release. Since these corresponding absolute insulin levels cannot entirely explain this hyperglycaemic effect of SOM230, other mechanisms seem involved in this glucose rise. If SOM230 would influence glucose homeostasis in peripheral target tissues of insulin action, expression of SS-receptors (sst) seems a logical necessity. In normal human liver tissues, analysed by quantitative polymerase chain reaction (PCR), the average sst1 mRNA expression level appeared significantly higher compared with sst2 (n = 6, relative copy number 161 +/- 46 vs. 57 +/- 6; P < 0.05). Fat tissue expressed both sst1 and sst2 mRNA, whereas in muscle only sst2 mRNA was found.

CONCLUSION

Both dosages of SOM230 inhibit free IGF-I in a more sustained fashion compared to OCT, implying longer duration of action. The superior action of OCT compared with SOM230 in stimulating IGFBP-1 levels, suggests direct regulation of IGFBP-1 by SRIF analogues via sst2. Finally, expression of only sst1 and sst2 in target tissues of insulin action, might point towards additional modulatory effects by SOM230 on glucose homeostasis.

Pharmacologic Therapies for Acromegaly

Acromegaly is associated with insulin resistance and an increased incidence of cardiovascular disease. However, it remains unclear to what extent the effects of growth hormone (GH) excess on cardiovascular morbidity and mortality are mediated through insulin resistance versus through other direct or indirect effects of GH. Adequate control of GH excess by surgery or pharmacologic interventions is associated with decreased insulin resistance, reflected in decreased plasma insulin levels and fasting glucose levels or improved glucose tolerance. Despite divergent effects of both somatostatin and somatostatin analogs on GH, insulin and glucagon secretion, and glucose absorption, treatment with the somatostatin analogs octreotide and lanreotide has only limited effects on glucose metabolism. However, glucose sensitivity has only been formally examined using a hyperinsulinemic euglycemic clamp in a minority of these studies. Treatment with the GH-receptor antagonist pegvisomant ameliorates insulin sensitivity, reflected in decreased fasting plasma insulin levels and fasting glucose levels. Nonetheless, the effect of pegvisomant on glucose sensitivity has not been formally tested by hyperinsulinemic clamp conditions. In acromegaly, preliminary observations on new octreotide analogs with greater specificity for somatostatin-receptor subtypes indicate that these compounds achieve better control of GH hypersecretion than octreotide, but may also negatively influence insulin release. Assessment of insulin secretion and glucose levels in acromegalic patients during administration of these compounds is thus mandatory.

Gross total resection or debulking of pituitary adenomas improves hormonal control of acromegaly by somatostatin analogs

INTRODUCTION

Invasive GH-secreting pituitary adenomas are rarely cured by surgery and although long-term therapy with somatostatin analogs (SSAs) may be employed, hormonal control is achieved in only 60% of cases. The impact of tumor debulking on subsequent control of acromegaly with SSAs has not been studied previously.

METHODS

We studied retrospectively the response to SSA therapy in acromegalic patients before and after incomplete surgical tumor excision. A case review identified 24 acromegalic patients who had received SSA therapy for > or = 1 month before and after gross total resection or debulking of adenomas. No patient received radiotherapy or combination treatment with SSAs and dopamine agonists during the study. GH and IGV-I responses to SSAs were recorded pre- and postoperatively. Postoperative SSA therapy was begun after a washout period of 1-3 months to assess the hormonal effects of the surgery alone.

RESULTS

Before preoperative SSA treatment, 24/24 (100%) patients had elevated GH levels and IGF-I levels were elevated in 19/21 (90.5%) patients with recorded values. During preoperative SSA treatment, GH and IGF-I levels were normalized in 7/24 (29.2%) and 11/24 (45.8%) patients respectively. Following postoperative washout, GH was controlled in only 3/24 (12.5%) patients, while IGF-I was controlled in 8/19 (42.1%) patients with available data. During the second SSA treatment period, normal GH levels were seen in 13/24 (54.2%) patients, while IGF-I control was noted in 18/23 (78.3%).

CONCLUSION

Gross total tumor resection or debulking increases the likelihood of achieving biochemical disease control with SSAs in acromegalic patients with adenomas that were not amenable to complete surgical resection and in whom primary SSA therapy was unable to achieve good biochemical control.

Treatment of Acromegaly

Mortality is increased in individuals with acromegaly unless serum growth hormone (GH) levels are below 2 microg/l and serum insulin-like growth factor (IGF)-I levels are normal following treatment. These combined criteria have been used to define remission of the disorder in this review. Transsphenoidal surgery achieves remission targets in an average of 55% of patients. For those not in remission following surgery, options include repeat surgery or use of adjuvant therapy. Fractionated external beam pituitary radiotherapy achieves 10-year remission rates of 47% but leaves patients exposed to excess GH until remission occurs. Stereotactic radiotherapy and gamma knife radiosurgery achieve remission rates of 40% over 3 years, and dopamine agonists produce remission in about 20% of patients. Somatostatin analogues induce remission in 59% of patients within the first year of treatment. The GH receptor antagonist pegvisomant leads to remission in 90% of patients, using IGF-I levels for assessment. Optimal treatment for a patient with acromegaly thus depends on the likely efficacy of treatment, cost, surgical skill, severity of side effects, tolerability, control of tumour growth, and improvement in complications related to tumour mass. A primary surgical approach, followed by medical therapy for those not in remission, remains the preferred option in most centres.

Octreotide long-acting release (LAR): a review of its use in the management of acromegaly

Octreotide long-acting release (LAR) is a somatostatin analogue designed for once monthly intramuscular injection. As with endogenous somatostatin, octreotide LAR inhibits secretion of growth hormone (GH) as well as various other peptide hormones. In the treatment of acromegaly, octreotide LAR effectively controlled the secretion of GH and insulin-like growth factor-1 (IGF-1) in about 55-70% of patients (n > 100) who had previously been treated with somatostatin analogues, a similar degree of control to that observed with subcutaneous octreotide and lanreotide slow release (SR). Progressive control of serum levels of GH and IGF-1 was achieved with octreotide LAR in clinical studies of up to 4 years' duration. In addition, primary therapy with octreotide LAR provided effective control of GH and IGF-1 secretion, particularly in patients with a pretreatment GH level <20 microg/L. The percentage of patients achieving a target serum GH level of <2-2.5 micro g/L or normal IGF-1 levels was significantly greater with octreotide LAR 10, 20 or 30 mg every 28 days than with lanreotide SR 30 mg every 7-14 days in a large (n = 125) sequential, 6-month study, but was not significantly different between treatment groups in a small, randomised, nonblind, parallel group study of previously untreated patients. The volume of pituitary tumour shrinkage achieved with octreotide LAR or lanreotide SR was also similar ( approximate, equals 33% after 24 months). Acromegaly symptoms, such as headache, increased perspiration, paraesthesia, fatigue and osteoarthralgia were improved during treatment with octreotide LAR or lanreotide SR. Overall, octreotide LAR is generally well tolerated by most patients. The incidence of gastrointestinal symptoms is about 30% but, in most cases, events are transient and mild to moderate. Gallbladder abnormalities (sediment, sludge, microlithiasis and gallstones) can occur, but only 1% have become symptomatic to date. The prevalence of biliary abnormalities did not change after switching from subcutaneous octreotide, or from lanreotide SR, to octreotide LAR. Glucose metabolism can be affected by octreotide LAR in some patients; about 15% become hyperglycaemic, usually mild in severity. In summary, octreotide LAR controls GH and IGF-1 secretion in about 55-70% of patients with acromegaly. Octreotide LAR is administered intramuscularly every 28 days, offering improved patient compliance and convenience over three-times-daily subcutaneous octreotide. Long-term therapy provides progressive control of serum GH and IGF-1 levels, and is generally well tolerated by most patients. Thus, for the medical management of acromegaly, octreotide LAR is an effective, well tolerated and convenient treatment option.

Diagnóstico e tratamento da acromegalia no Brasil

Acromegalia é uma doença debilitante e desfigurante que, se não controlada adequadamente, reduz a expectativa de vida do paciente. Complicações cardiovasculares e respiratórias representam as principais causas de morte nos acromegálicos. Atualmente, o diagnóstico é realizado de acordo com as diretrizes do consenso de 2000: ausência de supressão do GH para um valor <1ng/mL e IGF-1 elevado. Avanços em todas as modalidades terapêuticas têm ocorrido, propiciando o controle bioquímico da doença em um número cada vez maior de pacientes. Estudos prévios mostraram que a obtenção de níveis seguros de GH (GH médio <2,5ng/mL) e de IGF-1 normal reduz a taxa de mortalidade para o normal. Em 2002, foram publicadas diretrizes para o manejo da acromegalia, o qual envolve, muitas vezes, uma abordagem multidisciplinar. Neste artigo, fazemos uma avaliação crítica do que dispomos no Brasil para seguirmos as diretrizes estabelecidas nos consensos sobre diagnóstico e tratamento da acromegalia.

How effective are current therapies for acromegaly?

Currently available therapies for acromegaly are transsphenoidal surgery (TSS), radiotherapy (RT) and medical therapy with the dopamine agonists and somatostatin analogues. The goals of these therapies for acromegaly are to normalize excessive hormone secretion, thus normalizing serum levels of growth hormone (GH) and of insulin-like growth factors (IGF-I), to reduce the clinical signs and symptoms of acromegaly and to reduce tumor size in order to relieve any symptoms due to tumor mass effect. These goals should be accomplished while preserving pituitary function and with as few side effects as possible.TSS, the initial choice of therapy in most patients, is the most effective therapy at reducing the signs and symptoms of mass effect such as visual or neurological compromise. TSS is potentially curative, but the outcome is highly dependent on the tumor size, the degree of tumor invasion and the expertise of the surgeon. TSS can achieve biochemical control with normalization of IGF-I in 80-90% of patients with microadenomas and in 50-60% of those with macroadenomas. RT may be used as adjunctive therapy after unsuccessful surgery. RT can lower GH levels and normalize IGF-I levels, but there is a long lag time before this effect is achieved. Biochemical control is not achieved for 6-10 years after conventional fractionated RT; the time to clinical effect after gamma knife RT seems to be shorter. The most common complication after all forms of RT for acromegaly is the development of new hypopituitarism. Medical therapy has assumed the major role as adjunctive therapy of acromegaly. The dopamine agonists used for the therapy of acromegaly include bromocriptine, quinagolide and cabergoline. Cabergoline seems to be the most efficacious of the dopamine agonists for the treatment of acromegaly, with normalization of IGF-I being achieved in up to 35% of patients treated. Dopamine agonists are generally not effective at reducing the size of pure GH-secreting pituitary tumors. Somatostatin analogues are the most effective medical therapy currently available for acromegaly. The clinically available long-acting somatostatin analogues are long-acting octreotide and slow-release lanreotide. Overall, IGF-I levels normalize in about 66% of patients treated with long-acting octreotide and in 48% of patients treated with lanreotide. About 30% of GH-secreting tumors treated with somatostatin analogues as adjunctive therapy will have some shrinkage, and the amount of shrinkage usually ranges between 20 and 50% of tumor size. Signs and symptoms of the disease improve in about two-thirds of patients treated with long-acting somatostatin analogues. Gastrointestinal side effects are common when initiating somatostatin analogue therapy, but these effects do not typically limit continued use. Multi-modality therapy for acromegaly is often needed to achieve disease control. However, even combinations of currently available therapies cannot achieve all the goals of therapy in many patients with acromegaly.