The effects of somatostatin analogue therapy on pituitary tumor volume in patients with acromegaly

Investigational drugs for the treatment of acromegaly: new agents to transform therapy

INTRODUCTION

Disease control is essential to decrease morbidity burden and mortality in acromegaly patients. In the last decades, the availability of new drugs increased the rate of disease control. However, up to 55% of patients remain uncontrolled despite available treatment strategies in real-world data. The reasons for this finding may include poor adherence, inadequate tolerability, therapeutic inertia, and high costs. Since acromegaly is a chronic disease and medical therapy is usually life-long, patient's adherence to treatment is fundamental in both achieving and maintaining disease control. Less invasive routes of administration could improve adherence and concur to increase disease control rate.

AREAS COVERED

The aim of current review is to provide a detailed update about investigational drugs for acromegaly treatment currently under investigation as paltusotine, ONO-5788, AP102, GT-02037, ISIS 766720, CAM2024, Lanreotide PRF, DP1038, MTD201, solid dose injection of octreotide.

EXPERT OPINION

Medical therapy of acromegaly is an evolving field. Current studies are addressing patient's need for both new molecules and less invasive routes of administration for already existing drugs. It cannot be ruled out that drugs currently used for other diseases such as cancer could be considered in the future for the treatment of acromegaly.

Long-term pasireotide therapy in acromegaly: extensive real-life experience of a referral center

PURPOSE

Pasireotide is a novel therapeutic option for patients with acromegaly resistant to first-generation somatostatin receptor ligands. To date, real-life data are still scant, therefore, the aim of the current study is to evaluate the impact of long-term pasireotide therapy on disease control, pituitary tumor size, gluco-insulinemic and lipid profile in a real-life setting.

METHODS

Retrospective study of data prospectively collected, evaluating hormonal, tumoral, and metabolic data of 28 patients with acromegaly administered with pasireotide in a pituitary tertiary referral center.

RESULTS

Within the first 12 months of treatment, 70.4% of patients achieved normal IGF-I levels, which was maintained at 36-month evaluation in these responders patients. Patients who started with pasireotide 60 mg monthly exhibited significantly lower IGF-I levels after 36 months (p = 0.05) as compared to patients administered first with pasireotide 20 or 40 mg monthly. The maximal tumoral diameter was significantly decreased after 12 months of pasireotide (p < 0.001) and a further reduction was registered throughout the following months, with 41.2% of patients achieving a significant reduction (> 25% of baseline measurement) after 36 months of treatment. Fasting glucose significantly increased during the first 6 months (p < 0.001) with a gradual rise in diabetes prevalence during the following months, resulting diabetes prevalence after 36 months of pasireotide significantly increased compared to baseline (p = 0.003), although with glycated hemoglobin levels within the normal range. Diabetes was managed using oral glucose-lowering drugs or glucagon-like peptide 1 agonists, with no patient requiring insulin therapy. Pasireotide improved lipid profile, mainly during the first 12 months of treatment, by increasing HDL and decreasing triglycerides levels.

CONCLUSION

Pasireotide is effective and safe in the long-term. Hyperglycemia is a common event and is manageable even without insulin treatment.

Endocrinological aspects of pituitary adenoma surgery in Europe

Hormone-secreting adenomas are treated in many neurosurgical centers within Europe. The goal of the survey is to understand variance in practice management of pituitary tumors amongst neurosurgical centers. A list of departments performing pituitary surgery was created. The survey consisted of 58 questions. This study focuses on neurosurgical care of hormone-secreting adenomas. For analysis, the departments were divided into four subgroups: academic/non-academic, high-volume/low-volume, “mainly endoscopic/mainly microscopic practice” and geographical regions. Data from 254 departments from 34 countries were obtained. Most centers surgically treat 1–5 hormone-secreting adenomas per year. In prolactinomas this is the case in 194 centers, (76.4%), in GH-secreting adenomas: 133 centers, (52.4%), ACTH-secreting adenomas: 172 centers, (69.8%). Surgery as a primary treatment of prolactinomas is considered in 64 centers (25.2%). In 47 centers (18.8%), GH-secreting microadenomas are often treated pharmacologically first. Debulking surgery for an invasive GH-secreting adenoma in which hormonal remission is not a realistic goal of the surgery and the patient has no visual deficit surgery is always or mostly indicated in 156 centers (62.9%). Routine postoperative hydrocortisone replacement therapy is administered in 147 centers (58.6%). Our survey shows that in most centers, few hormone-secreting adenomas are treated per year. In about 25% of the centers, prolactinoma surgery may be regarded as first-line treatment; in about 20% of the centers, medical treatment is the first-line treatment for GH-secreting adenomas. Pretreatment for ACTH-secreting adenomas is routinely used in 21% of centers. This survey may serve as plea for neurosurgical care centralization of hormone-secreting adenomas.

Oral Octreotide: A Review of Recent Clinical Trials and Practical Recommendations for Its Use in the Treatment of Patients With Acromegaly

OBJECTIVE

Acromegaly is characterized by chronic growth hormone (GH) and insulin-like growth factor-I (IGF-I) hypersecretion, often caused by a GH-secreting pituitary adenoma. Surgery remains first line, but medical therapy is essential if surgery is contraindicated, does not achieve remission, or does not prevent recurrence despite apparent surgical remission. Oral octreotide capsules (OOC) that combine octreotide with a transient permeability enhancer technology are the first oral somatostatin receptor ligand (SRL) approved in the US for acromegaly.

METHODS

We review the literature and clinical trial data of OOC for patients with acromegaly and discuss clinical assessment of OOC use, potential drug-drug interactions, drug initiation, dose titration, and monitoring of drug efficacy and tolerability.

RESULTS

Four pivotal clinical trials involving a total of 238 patients with acromegaly treated with OOC effective suppression of serum GH and IGF-I levels, maintenance of disease control, decreased breakthrough symptoms and symptomatic improvement with noninferiority of OOC to injectable SRLs (iSRLs) in maintaining biochemical response. Additionally, the safety profile of OOC is comparable to that of iSRLs. Most patients who completed the clinical trials of OOC have also expressed preference to oral compared to iSRL administration.

CONCLUSION

OOC is an effective treatment option for patients with acromegaly who previously responded to iSRLs, with the benefits of avoiding injection-related side effects. This article provides a review of the pharmacology, safety, and efficacy and offers practical recommendations on utilization of OOCs to treat iSRL-responsive patients with acromegaly.

Evaluation of acromegaly treatment direct costs with respect to biochemical control and follow-up length

PURPOSE

Acromegaly is a severe chronic endocrine disease. Achieving biochemical control often needs a multimodal treatment approach, including prolonged medical treatment. Aim of the study is to evaluate the burden of treatment direct costs with respect to the different therapeutic strategies, disease control, and follow-up length.

METHODS

Single center retrospective study on 73 acromegaly patients. Costs of acromegaly treatments were computed based on a detailed revision of patients' clinical charts.

RESULTS

Median total treatment cost/patient was €47,343 during the entire follow-up (8 years), while median treatment cost/patient/year was €6811. The majority of patients received medical therapy (71/73, 97.3%). Median cost for first-line medical treatment (first-generation somatostatin receptor ligands) was lower compared to second-line treatments (pegvisomant monotherapy or combination therapies), considering both total (€22,824 vs €76,140; p < 0.001), and yearly cost/patient (€4927 vs €9161; p < 0.001). Sixty patients (82.2%) reached biochemical control at last follow-up (IGF-1 ≤ 1 xULN). The percentage of patients treated with first- or second-line medical therapies was comparable between controlled and uncontrolled patients (p = 1.000), and the yearly cost/patient did not significantly differ between the two groups (€6936 vs €6680; p = 0.829). Follow-up duration was significantly longer in controlled patients compared to the uncontrolled ones (8.7 vs 3.5 years; p = 0.019).

CONCLUSIONS

Direct costs for the management of acromegaly have a significant burden on the healthcare systems. However, more than 80% of our patients reached biochemical control using multimodal approaches. Treatment modalities and yearly costs did not significantly differ between controlled and uncontrolled patients, while follow-up length represented a major determinant of biochemical outcome.

Current and Emerging Medical Therapies in Pituitary Tumors

Pituitary tumors (PT) represent in, the majority of cases, benign tumors for which surgical treatment still remains, except for prolactin-secreting PT, the first-line therapeutic option. Nonetheless, the role played by medical therapies for the management of such tumors, before or after surgery, has evolved considerably, due in part to the recent development of well-tolerated and highly efficient molecules. In this review, our aim was to present a state-of-the-art of the current medical therapies used in the field of PT and the benefits and caveats for each of them, and further specify their positioning in the therapeutic algorithm of each phenotype. Finally, we discuss the future of PT medical therapies, based on the most recent studies published in this field.

Role of Somatostatin Signalling in Neuroendocrine Tumours

Somatostatin (SST) is a small peptide that exerts inhibitory effects on a wide range of neuroendocrine cells. Due to the fact that somatostatin regulates cell growth and hormone secretion, somatostatin receptors (SSTRs) have become valuable targets for the treatment of different types of neuroendocrine tumours (NETs). NETs are a heterogeneous group of tumours that can develop in various parts of the body, including the digestive system, lungs, and pituitary. NETs are usually slow growing, but they are often diagnosed in advanced stages and can display aggressive behaviour. The mortality rate of NETs is not outstandingly increased compared to other malignant tumours, even in the metastatic setting. One of the intrinsic properties of NETs is the expression of SSTRs that serve as drug targets for SST analogues (SSAs), which can delay tumour progression and downregulate hormone overproduction. Additionally, in many NETs, it has been demonstrated that the SSTR expression level provides a prognostic value in predicting a therapeutic response. Furthermore, higher a SSTR expression correlates with a better survival rate in NET patients. In recent studies, other epigenetic regulators affecting SST signalling or SSA–mTOR inhibitor combination therapy in NETs have been considered as novel strategies for tumour control. In conclusion, SST signalling is a relevant regulator of NET functionality. Alongside classical SSA treatment regimens, future advanced therapies and treatment modalities are expected to improve the disease outcomes and overall health of NET patients.

Personalized Medical Treatment in Patients with Acromegaly: A Review

Acromegaly is associated with significant morbidity and mortality if not appropriately treated. In addition to insulin-like growth factor 1 (IGF-1) and growth hormone (GH) normalization, and tumor shrinkage, treatment goals include symptom relief, managing complications and improving quality of life. Surgical resection is a first-line treatment in most patients, with few being pretreated pre-operatively with medications. Somatostatin receptor ligands (SRLs), injectable and more recently oral capsules, have been the cornerstone of first-line medical therapy for persistent disease. However, several factors, including sparsely granulated adenomas, absent/low somatostatin receptor (SSTR2) status, imaging T2-hyperintensity, young age and aryl hydrocarbon receptor interacting protein mutations could predict first-generation SRL resistance. Patients with these characteristics may be better candidates for the GH receptor antagonist, pegvisomant, or in cases of large tumors the second-generation SRL, pasireotide. Combination therapy should be further pursued in patients who remain biochemically uncontrolled or have high remnant tumor after monotherapy. An efficacious and cost-effective pegvisomant dose-sparing effect of SRLs when used in combination has been demonstrated. With such a wide array of medical treatment options, it is increasingly important to tailor treatment to patients' unique characteristics as well as preferences, with a goal of personalizing management to achieve high quality outcomes.

Long-term effects of somatostatin analogues in rat GH-secreting pituitary tumor cell lines

PURPOSE

First-generation somatostatin analogs, octreotide (OCT) and lanreotide, are the cornerstone for the medical treatment of growth hormone (GH)-secreting pituitary tumors. A new multireceptor analog, such as pasireotide (PAS), showed better activity than OCT in long-term treatment of patients with acromegaly, but modulation of intracellular key processes is still unclear in vitro. In this study, we evaluated the antitumor activity of OCT and PAS in two GH-secreting pituitary tumor cell lines, GH3 and GH4C1, after a long-term incubation.

METHODS

The effects of PAS and OCT on the cell viability, cell cycle, apoptosis, GH secretion, and tumor-induced angiogenesis have been evaluated through a colorimetric method (MTS Assay), DNA flow cytometry with propidium iodide, and Annexin V-FITC/propidium iodide staining, ELISA assay and zebrafish platform, respectively.

RESULTS

PAS showed a more potent antitumor activity compared to OCT in GH3 cell line exerted through inhibition of cell viability, perturbation of cell cycle progression, and induction of apoptosis after 6 days of incubation. A concomitant decrease in GH secretion has been observed after 2 days of incubation only with PAS. No effect on tumor-induced angiogenesis has been reported after treatment with OCT or PAS in zebrafish/tumor xenograft model.

CONCLUSION

Long-term incubation with PAS showed a more potent antitumor activity than that reported after OCT in GH3 cells, mainly modulated by a cell cycle perturbation and a relevant induction in apoptosis.

Epigenetic and post-transcriptional regulation of somatostatin receptor subtype 5 (SST5 ) in pituitary and pancreatic neuroendocrine tumors

Somatostatin receptor subtype 5 (SST₅) is an emerging biomarker and actionable target in pituitary (PitNETs) and pancreatic (PanNETs) neuroendocrine tumors. Transcriptional and epigenetic regulation of SSTR5 gene expression and mRNA biogenesis is poorly understood. Recently, an overlapping natural antisense transcript, SSTR5‐AS1, potentially regulating SSTR5 expression, was identified. We aimed to elucidate whether epigenetic processes contribute to the regulation of SSTR5 expression in PitNETs (somatotropinomas) and PanNETs. We analyzed the SSTR5/SSTR5‐AS1 human locus in silico to identify CpG islands. SSTR5 and SSTR5‐AS1 expression was assessed by quantitative real‐time PCR (qPCR) in 27 somatotropinomas, 11 normal pituitaries (NPs), and 15 PanNETs/paired adjacent (control) samples. We evaluated methylation grade in four CpG islands in the SSTR5/SSTR5‐AS1 genes. Results revealed that SSTR5 and SSTR5‐AS1 were directly correlated in NP, somatotropinoma, and PanNET samples. Interestingly, selected CpG islands were differentially methylated in somatotropinomas compared with NPs. In PanNETs cell lines, SSTR5‐AS1 silencing downregulated SSTR5 expression, altered aggressiveness features, and influenced pasireotide response. These results provide evidence that SSTR5 expression in PitNETs and PanNETs can be epigenetically regulated by the SSTR5‐AS1 antisense transcript and, indirectly, by DNA methylation, which may thereby impact tumor behavior and treatment response.

Obesity-related gut hormones and cancer: novel insight into the pathophysiology

The number of cancers attributed to obesity is increasing over time. The mechanisms classically implicated in cancer pathogenesis and progression in patients with obesity involve adiposity-related alteration of insulin, sex hormones, and adipokine pathways. However, they do not fully capture the complexity of the association between obesity-related nutritional imbalance and cancer. Gut hormones are secreted by enteroendocrine cells along the gastrointestinal tract in response to nutritional cues, and act as nutrient sensors, regulating eating behavior and energy homeostasis and playing a role in immune-modulation. The dysregulation of gastrointestinal hormone physiology has been implicated in obesity pathogenesis. For their peculiar function, at the cross-road between nutrients intake, energy homeostasis and inflammation, gut hormones might represent an important but still underestimated mechanism underling the obesity-related high incidence of cancer. In addition, cancer research has revealed the widespread expression of gut hormone receptors in neoplastic tissues, underscoring their implication in cell proliferation, migration, and invasion processes that characterize tumor growth and aggressiveness. In this review, we hypothesize that obesity-related alterations in gut hormones might be implicated in cancer pathogenesis, and provide evidence of the pathways potentially involved.

Early postoperative prediction of both disease remission and long-term disease control in acromegaly using the oral glucose tolerance test

PURPOSE

Transsphenoidal surgery (TSS) is the cornerstone of acromegaly treatment. Two biochemical parameters, growth hormone (GH) and insulin-like growth factor-1 (IGF-1) levels, sometimes diverge postoperatively; however, it is important to maintain disease control without further treatment, regardless of whether these parameters converge. This study investigated whether remission and long-term disease control could be predicted using early postoperative GH and IGF-1 levels.

METHODS

We reviewed 36 consecutive surgically treated patients with acromegaly. IGF-1 levels and minimum GH levels during an oral glucose tolerance test (OGTT) were evaluated at 2 weeks, as well as at 3 months postoperatively. After comparison between the remission and nonremission groups, we analyzed whether early postoperative parameters could predict remission and long-term disease control.

RESULTS

Twenty-five patients (69.4%, Group A) achieved remission within 1 year postoperatively. Of the remaining patients (median follow-up period, 53 months), seven (19.5%, Group B) maintained normal IGF-1 levels without treatment, whereas four (11.1%, Group C) required additional treatment. GH levels <1.5 ng/mL measured on the morning after surgery and nadir GH levels <0.7 ng/mL during the OGTT conducted at 2 weeks postoperatively were predictive of remission, with the latter demonstrating 95.2% sensitivity and 100% specificity. All group C patients had nadir GH levels ≥0.7 ng/mL during the OGTT and IGF-1 levels ≥SD +3 at 2 weeks postoperatively.

CONCLUSION

Early postoperative nadir GH levels during the OGTT and IGF-1 levels at 2 weeks postoperatively demonstrated excellent predictive value for both endocrinological remission and the necessity for additional treatment.

The Dose of Somatostatin Analogues during Pre-Surgical Treatment Is a Key Factor to Achieve Surgical Remission in Acromegaly

Purpose: to determine whether pre-surgical treatment using long-acting somatostatin analogues (SSAs) may improve surgical outcomes in acromegaly. Methods: retrospective study of 48 patients with acromegaly operated by endoscopic transsphenoidal approach and for first time. Surgical remission was evaluated based on the 2010 criteria. Results: most patients, 83.3% (n = 40), harbored macroadenomas and 31.3% (n = 15) invasive pituitary adenomas. In this case, 14 patients were treated with lanreotide LAR and 6 with octreotide LAR, median monthly doses of 97.5 [range 60–120] and 20 [range 20–30] mg, respectively, for at least 3 months preoperatively. Presurgical variables were comparable between pre-treated and untreated patients (p > 0.05). Surgical remission was more frequent in those pre-treated with monthly doses ≥90 mg of lanreotide or ≥30 mg of octreotide than in untreated or pre-treated with lower doses (OR = 4.64, p = 0.025). However, no differences were found between pre-treated and untreated patients when lower doses were included or between those treated for longer than 6 months compared to those untreated or pre-treated for shorter than 6 months. Similarly, no differences were found either in terms of surgical or endocrine complications (OR = 0.65, p = 0.570), independently of the doses and the duration of SSA treatment (p > 0.05). Conclusions: the dose of SSAs is a key factor during pre-surgical treatment, since the beneficial effects in surgical remission were observed with monthly doses equal or higher than 90 mg of lanreotide and 30 mg of octreotide, but not with lower doses.

Large Scale Molecular Studies of Pituitary Neuroendocrine Tumors: Novel Markers, Mechanisms and Translational Perspectives

Simple Summary

Pituitary neuroendocrine tumors are non-cancerous tumors of the pituitary gland, that may overproduce hormones leading to serious health conditions or due to tumor size cause chronic headache, vertigo or visual impairment. In recent years pituitary neuroendocrine tumors are studied with the latest molecular biology methods that simultaneously investigate a large number of factors to understand the mechanisms of how these tumors develop and how they could be diagnosed or treated. In this review article, we have studied literature reports, compiled information and described molecular factors that could affect the development and clinical characteristics of pituitary neuroendocrine tumors, discovered factors that overlap between several studies using large scale molecular analysis and interpreted the potential involvement of these factors in pituitary tumor development. Overall, this study provides a valuable resource for understanding the biology of pituitary neuroendocrine tumors.

Abstract

Pituitary neuroendocrine tumors (PitNETs) are non-metastatic neoplasms of the pituitary, which overproduce hormones leading to systemic disorders, or tumor mass effects causing headaches, vertigo or visual impairment. Recently, PitNETs have been investigated in large scale (exome and genome) molecular analyses (transcriptome microarrays and sequencing), to uncover novel markers. We performed a literature analysis on these studies to summarize the research data and extrapolate overlapping gene candidates, biomarkers, and molecular mechanisms. We observed a tendency in samples with driver mutations (GNAS, USP8) to have a smaller overall mutational rate, suggesting driver-promoted tumorigenesis, potentially changing transcriptome profiles in tumors. However, direct links from drivers to signaling pathways altered in PitNETs (Notch, Wnt, TGF-β, and cell cycle regulators) require further investigation. Modern technologies have also identified circulating nucleic acids, and pinpointed these as novel PitNET markers, i.e., miR-143-3p, miR-16-5p, miR-145-5p, and let-7g-5p, therefore these molecules must be investigated in the future translational studies. Overall, large-scale molecular studies have provided key insight into the molecular mechanisms behind PitNET pathogenesis, highlighting previously reported molecular markers, bringing new candidates into the research field, and reapplying traditional perspectives to newly discovered molecular mechanisms.

Medication for Acromegaly Reduces Expression of MUC16, MACC1 and GRHL2 in Pituitary Neuroendocrine Tumour Tissue

Acromegaly is a disease mainly caused by pituitary neuroendocrine tumor (PitNET) overproducing growth hormone. First-line medication for this condition is the use of somatostatin analogs (SSAs), that decrease tumor mass and induce antiproliferative effects on PitNET cells. Dopamine agonists (DAs) can also be used if SSA treatment is not effective. This study aimed to determine differences in transcriptome signatures induced by SSA/DA therapy in PitNET tissue. We selected tumor tissue from twelve patients with somatotropinomas, with half of the patients receiving SSA/DA treatment before surgery and the other half treatment naive. Transcriptome sequencing was then carried out to identify differentially expressed genes (DEGs) and their protein–protein interactions, using pathway analyses. We found 34 upregulated and six downregulated DEGs in patients with SSA/DA treatment. Three tumor development promoting factors MUC16, MACC1, and GRHL2, were significantly downregulated in therapy administered PitNET tissue; this finding was supported by functional studies in GH3 cells. Protein–protein interactions and pathway analyses revealed extracellular matrix involvement in the antiproliferative effects of this type of the drug treatment, with pronounced alterations in collagen regulation. Here, we have demonstrated that somatotropinomas can be distinguished based on their transcriptional profiles following SSA/DA therapy, and SSA/DA treatment does indeed cause changes in gene expression. Treatment with SSA/DA significantly downregulated several factors involved in tumorigenesis, including MUC16, MACC1, and GRHL2. Genes that were upregulated, however, did not have a direct influence on antiproliferative function in the PitNET cells. These findings suggested that SSA/DA treatment acted in a tumor suppressive manner and furthermore, collagen related interactions and pathways were enriched, implicating extracellular matrix involvement in this anti-tumor effect of drug treatment.

Predictive and prognostic significance of tumour subtype, SSTR1-5 and e-cadherin expression in a well-defined cohort of patients with acromegaly

In somatotroph pituitary tumours, somatostatin analogue (SSA) therapy outcomes vary throughout the studies. We performed an analysis of cohort of patients with acromegaly from the Czech registry to identify new prognostic and predictive factors. Clinical data of patients were collected, and complex immunohistochemical assessment of tumour samples was performed (SSTR1‐5, dopamine D2 receptor, E‐cadherin, AIP). The study included 110 patients. In 31, SSA treatment outcome was evaluated. Sparsely granulated tumours (SGST) differed from the other subtypes in expression of SSTR2A, SSTR3, SSTR5 and E‐cadherin and occurred more often in young. No other clinical differences were observed. Trouillas grading system showed association with age, tumour size and SSTR2A expression. Factors significantly associated with SSA treatment outcome included age, IGF1 levels, tumour size and expression of E‐cadherin and SSTR2A. In the group of SGST, poor SSA response was observed in younger patients with larger tumours, lower levels of SSTR2A and higher Ki67. We observed no relationship with expression of other proteins including AIP. No predictive value of E‐cadherin was observed when tumour subtype was considered. Multiple additional factors apart from SSTR2A expression can predict treatment outcome in patients with acromegaly.

Pasireotide in the Personalized Treatment of Acromegaly

The delay in controlling the disease in patients who do not respond to first-line treatment with first generation somatostatin receptor ligands (first-generation SRLs) can be quantified in years, as every modification in the medical therapy requires some months to be fully evaluated. Considering this, acromegaly treatment should benefit from personalized medicine therapeutic approach by using biomarkers identifying drug response. Pasireotide has been positioned mostly as a compound to be used in first-generation SRLs resistant patients and after surgical failure, but sufficient data are now available to indicate it is a first line therapy for patients with certain characteristics. Pasireotide has been proved to be useful in patients in which hyperintensity T2 MRI signal is shown and in those depicting low SST2 and high expression of SST5, low or mutated AIP condition and sparsely granulated immunohistochemical pattern. This combination of clinical and pathological characteristics is unique for certain patients and seems to cluster in the same cases, strongly suggesting an etiopathogenic link. Thus, in this paper we propose to include this clinico-pathologic phenotype in the therapeutic algorithm, which would allow us to use as first line medical treatment those compounds with the highest potential for achieving the fastest control of GH hypersecretion as well as a positive effect upon tumor shrinkage, therefore accelerating the implementation of precision medicine for acromegaly. Moreover, we suggest the development, validation and clinical use of a pasireotide acute test, able to identify patients responsive to pasireotide LAR as the acute octreotide test is able to do for SRLs.

Efficacy and predictors of short-term first-generation somatostatin analog presurgical treatment in acromegaly: A hospital-based study of 237 cases

OBJECTIVE

To investigate the effectiveness and predictors of short-term somatostatin analog (SSA) presurgical therapy in a large cohort and to assess the correlation between clinical and pathological variables.

DESIGN

237 newly diagnosed patients with acromegaly received presurgical SSA treatment for three months were recruited. Clinical characteristics were collected, and response to SSA in hormone and tumor size was evaluated. The correlation between clinical information and pathological variables were analyzed.

RESULTS

After 3 months presurgical SSA therapy, 51 (21.5%) patients were biochemically responsive with ≥50% decrease in IGF-1 while 126 (53.2%) patients showed at least 20% tumor size decrease. Biochemical responders were associated with a smaller maximum tumor diameter (MTD) and an older age (OR, 0.448; P = 0.003; OR, 1.050; P = 0.001). Tumor size responders were associated with a smaller MTD (OR, 0.435; P < 0.001). A combination of MTD < 2 cm and age ≥49 years predicted biochemical responders (PPV, 54.5%; NPV, 86.0%; P < 0.001), while MTD ≤2.2 cm (PPV, 67.1%; NPV, 67.0%; P < 0.001) predicted tumor size responders. Compared to patients with MTD < 2 cm, patients with MTD ≥ 2 cm showed higher percentage of sparsely granulated (SG) adenoma (62.1% vs. 31.3%, P = 0.005). In addition, the percentage of SG adenoma tended to be higher in patients < 49 years than ≥49 years (48.1% and 31.0% P = 0.089).

CONCLUSIONS

The baseline MTD and age correlate with granulation patterns and may be used as easily acquired predictors of presurgical SSA treatment in acromegaly. Patients over their 50s with a tumor less than 2 cm in diameter are more likely to have a response to the short-term presurgical SSA therapy.

Autophagy and Pituitary Adenoma

Pituitary adenomas (PAs) are common, benign intracranial tumors that are usually effectively controlled with surgery, pharmacotherapy or radiotherapy. Some PAs against which conventional treatment is ineffective are great clinical challenges at present. Autophagy is a widespread physiological process in cells. Through autophagy, cells can degrade damaged or redundant proteins and organelles and achieve the recycling of intracellular substances to maintain the homeostasis of the intracellular environment. An increasing number of studies have demonstrated the importance of autophagy in tumor therapy. Both radiotherapy and chemotherapy can induce autophagy, which plays different roles in the course of therapy. In recent years, there has been growing interest in the role of autophagy during the treatment of PAs. This chapter reviews the recent progress of research on autophagy in PA and the autophagic mechanisms in the treatment of PA.

Normal Insulin-like Growth Factor 1 During Somatostatin Receptor Ligand Treatment Predicts Surgical Cure in Acromegaly

CONTEXT

Treatment with somatostatin receptor ligands (SRLs) is often given before pituitary surgery to patients with acromegaly.

OBJECTIVE

To study whether the response to treatment with SRLs is predictive of surgical outcome.

DESIGN

Retrospective, observational study.

SETTING

Tertiary care center.

PATIENTS

We investigated 272 patients with acromegaly who had been treated with an SRL between 1990 and 2018.

INTERVENTION

All patients underwent pituitary surgery performed by a skilled neurosurgeon.

MAIN OUTCOME MEASURE

Outcome of pituitary surgery in patients who had normalization of insulin-like growth factor 1 (IGF-1) levels during SRL therapy in comparison with patients who did not normalize IGF-1 levels.

RESULTS

Normalization of IGF-1 levels during SRL treatment occurred in 62 patients (22.8%) and was similar for the 3 different types of SRL (P = .88). Surgical remission occurred in 59.6% of the patients. Patients who normalized IGF-1 levels during SRL treatment had a higher probability of surgical cure than patients without IGF-1 normalization (83.9% vs 52.4%, respectively; P < .001). Multivariate analysis confirmed that lack of cavernous sinus invasion, small maximum tumor diameter, and IGF-1 normalization during SRL therapy were the only factors independently associated with a favorable surgical outcome.

CONCLUSIONS

Our study demonstrates that the normalization of IGF-1 levels during treatment with SRLs is an independent predictive factor of a favorable surgical outcome. The underlying mechanisms remain unclear, but an optimal response to medical therapy may be a characteristic of less aggressive tumors that are more likely to be entirely removed at surgery.

Systematic review and network meta-analysis assess the comparative efficacy and safety of transsphenoidal surgery for pituitary tumor

To quantitatively synthesize the comparative efficacy and safety of the most common surgical approaches including endonasal transsphenoidal endoscopic surgery (ETES), sublabial transsphenoidal microsurgery (STMS) and endonasal transsphenoidal microsurgery (ETMS) for all kinds of pituitary tumors. This systematic review and network meta-analysis was performed on randomized controlled trials (RCTs) and comparison studies from databases of Pubmed, EMBASE, and the Cochrane library. We selected the rate of gross complete resection as our primary outcome of efficacy. And the incidence of all complications, cerebrospinal fluid (CSF) leak, diabetes insipidus, nasal septal perforation, death, and bleeding were designed as our primary outcomes of safety. Twenty-seven studies with 2618 patients were included in this network meta-analysis. On efficacy, there was no statistical difference among the three methods including ETES, STMS, and ETMS. As for safety, results indicated that the incidence of total complications of STMS (OR = 4.74; 95% CI 1.03, 40.14) is significantly superior to ETES. And the incidence of diabetes insipidus of ETMS (OR = 2.21; 95% CI 1.31, 3.81) was significantly superior to that of ETES. Besides, there was no statistical difference in the other complications including CSF leak, nasal septal perforation, death, and bleeding. We clarified the overpraise of the efficacy of endoscopy especially the endonasal transsphenoidal approach, and verified that all the approaches owned similar efficacy. Moreover, we recommended the endoscopy to be the first choice for pituitary tumors, because it demonstrated the best safety.

Somatostatin receptor expression and mTOR pathway activation in glioneuronal tumours of childhood

PURPOSE

To investigate the expression of somatostatin receptors (SSTRs) and markers of mTOR pathway in paediatric glioneuronal tumours and correlate these findings with tumour type, BRAFV600E mutational status and clinical characteristics such as tumour location, seizure frequency and duration, and age.

METHOD

37 children and adolescents with a neuropathological diagnosis of glioneuronal tumour were identified over a 22-year period. Immunohistochemical analyses for SSTRs type 1, 2A, 3, 5 and ezrin-radixin-moesin (ERM) and phosphorylated S6 (pS6), which are indicators of mTOR pathway activation, were performed in tumour specimens from 33 patients and evaluated using the immunoreactive score (IRS). The IRS were compared to tumour type, BRAFV600E status and clinical characteristics.

RESULTS

Ganglioglioma (GG) was the most frequently encountered subgroup (n = 27), followed by dysembryoplastic neuroepithelial tumour (DNET; n = 4). GGs expressed SSTR2A and SSTR3 to a high extent, 56 % and 44 % respectively. Expression of SSTR2A was also found in DNETs. Signs of mTOR pathway activation were abundant in GGs, but only present in one DNET. No correlations with BRAFV600E presence or clinical characteristics were found.

CONCLUSIONS

Expression of SSTRs and activation of mTOR pathway in paediatric glioneuronal tumour suggest that somatostatin analogues and mTOR inhibitors may have potential therapeutic implications in a subset of inoperable childhood glioneuronal tumours causing medically refractory epilepsy and/or tumour growth. Further clinical studies are warranted to validate these findings.

Italian Association of Clinical Endocrinologists (AME) and Italian AACE Chapter Position Statement for Clinical Practice: Acromegaly - Part 2: Therapeutic Issues

Any newly diagnosed patient should be referred to a multidisciplinary team experienced in the treatment of pituitary adenomas. The therapeutic management of acromegaly always requires a personalized strategy. Normal age-matched IGF-I values are the treatment goal. Transsphenoidal surgery by an expert neurosurgeon is the primary treatment modality for most patients, especially if there are neurological complications. In patients with poor clinical conditions or who refuse surgery, primary medical treatment should be offered, firstly with somatostatin analogs (SSAs). In patients who do not reach hormonal targets with first-generation depot SSAs, a second pharmacological option with pasireotide LAR or pegvisomant (alone or combined with SSA) should be offered. Irradiation could be proposed to patients with surgical remnants who would like to be free from long-term medical therapies or those with persistent disease activity or tumor growth despite surgery or medical therapy. Since the therapeutic tools available enable therapeutic targets to be achieved in most cases, the challenge is to focus more on the quality of life.

Statins Directly Regulate Pituitary Cell Function and Exert Antitumor Effects in Pituitary Tumors

INTRODUCTION

Pituitary neuroendocrine tumors (PitNETs), the most abundant of all intracranial tumors, entail severe comorbidities. First-line therapy is transsphenoidal surgery, but subsequent pharmacological therapy is often required. Unfortunately, many patients are/become unresponsive to available drugs (somatostatin analogues [SSAs]/dopamine agonists), underscoring the need for new therapies. Statins are well-known drugs commonly prescribed to treat hyperlipidemia/cardiovascular diseases, but can convey additional beneficial effects, including antitumor actions. The direct effects of statins on normal human pituitary or PitNETs are poorly known. Thus, we aimed to explore the direct effects of statins, especially simvastatin, on key functional parameters in normal and tumoral pituitary cells, and to evaluate the combined effects of simvastatin with metformin (MF) or SSAs.

METHODS

Effects of statins in cell proliferation/viability, hormone secretion, and signaling pathways were evaluated in normal pituitary cells from a primate model (Papio anubis), tumor cells from corticotropinomas, somatotropinomas, nonfunctioning pituitary tumors, and PitNET cell-lines (AtT20/GH3-cells).

RESULTS

All statins decreased AtT20-cell proliferation, simvastatin showing stronger effects. Indeed, simvastatin reduced cell viability and/or hormone secretion in all PitNETs subtypes and cell-lines, and ACTH/GH/PRL/FSH/LH secretion (but not expression), in primate cell cultures, by modulating MAPK/PI3K/mTOR pathways and expression of key receptors (GH-releasing hormone-receptor/ghrelin-R/Kiss1-R) regulating pituitary function. Addition of MF or SSAs did not enhance simvastatin antitumor effects.

CONCLUSION

Our data reveal direct antitumor effects of simvastatin on PitNET-cells, paving the way to explore these compounds as a possible tool to treat PitNETs.

Multimodal therapy in aggressive pituitary tumors

The concept of aggressive pituitary tumor (APT) has been precisely defined in recent years. These tumors are characterized by morphological (radiological or histopathological) data of invasion, proliferative activity superior to that of typical adenomas and a clinical behavior characterized by resistance to standard therapies and frequent recurrences. The absence of cerebrospinal or distant metastases differentiates them from the pituitary carcinoma. APTs account for about 10% of all pituitary neoplasm. Proper diagnostic implies participation not only of radiological and hormonal investigation but also a thorough pathological assessment including proliferation markers and immunohistochemistry for hormones and transcription factors. Surgical resection, aiming gross total resection or tumor debulking, is the mainstay initial therapy in most patients. Most patients with APTs need more than one surgical intervention, pituitary radiation, sometimes on more than one occasion, and multiple sequential or combined medical treatments, to finally be doomed to unusual treatments, such as alkylating agents (temozolomide alone or in combination), molecular targeted therapies, or peptide receptor radionuclide therapy. Multimodal therapy, implemented by experts, preferably in specialized centers with high volume caseload, is the only way to improve the prognosis of patients with these uncommon tumors. The research needs in this area are multiple and include a greater knowledge of the molecular biology of these tumors, establishment of protocols for monitoring and sequencing of treatments, development of multicenter studies and international registries.

The Use of Prophylactic Somatostatin Therapy Following Pancreaticoduodenectomy: A Meta-analysis of Randomised Controlled Trials

BACKGROUND

Prophylactic administration of somatostatin analogues (SA) to reduce the incidence of post-operative pancreatic fistula (POPF) remains contentious. This meta-analysis evaluated its impact on outcomes following pancreaticoduodenectomy (PD).

METHODS

The EMBASE, MEDLINE and Cochrane databases were searched for randomised controlled trials (RCTs) investigating prophylactic SA following PD. Comparative effects were summarised as odds ratio and weighted mean difference based on an intention to treat. Quantitative pooling of the effect sizes was derived using the random-effects model.

MAIN RESULTS

Twelve RCTs were included involving 1615 patients [SA-treated group (n = 820) and control group (n = 795)]. The SA used included somatostatin-14, pasireotide, vapreotide and octreotide. Pooling of the data showed no significant benefit of its use for the primary outcome measure of all grades of POPF, odds ratio (OR) 0.73 [95% confidence interval (CI), 0.51-1.05, p = 0.09] and clinically relevant POPF, OR 0.48 [95% CI, 0.22-1.06, p = 0.07]. There were no benefits in the secondary outcome measures of delayed gastric emptying, OR 0.98 [95% CI, 0.57-1.69, p = 0.94]; infected abdominal collections, OR 0.80 [95% CI, 0.44-1.43, p = 0.80]; reoperation rates, OR 1.24 [95% CI, 0.73-2.13, p = 0.42]; duration of hospital stay, - 0.23 [95% CI - .59 to 1.13, p = 0.74]; and mortality, 1.78 [95% CI, 0.94-3.39, p = 0.08].

CONCLUSION

SA did not improve the post-operative outcomes following PD, including reducing the incidence of POPF. The routine administration of SA cannot be recommended following PD.

Pituitary magnetic resonance imaging predictive role in the therapeutic response of growth hormone-secreting pituitary adenomas

Background

Growth hormone (GH)-secreting pituitary adenomas, responsible for the development of acromegaly, are the second most frequent type of secreting pituitary adenomas and are characterized by very variable T2-weighted signal intensity on pituitary magnetic resonance imaging (MRI). Previous data have demonstrated a correlation between T2-weighted tumor signal intensity and response to therapy with conventional somatostatin analogs (SSA) in patients with acromegaly. The aim of the current retrospective study was to investigate the correlation between the T2-weighted tumor signal on pituitary MRI and both biochemical and radiological response to first-line SSA therapy.

Methods

Twenty-two naive patients with acromegaly were eligible for the study (14 females and 8 males, mean age ± SD: 58.8±15.74). A biochemical evaluation (GH and IGF-I levels) and an MRI assessment (volume and signal intensity analysis of adenoma) were conducted in each patient at diagnosis and after 12 months of SSA therapy.

Results

On diagnostic pituitary MRI, 16 (72.7%) adenomas were T2- hypointense and 6 (27.2%) T2-hyperintense. After 12 months of SSA therapy, IGF-I levels decreased by more than 50% from baseline in 62.5% of patients with T2-hypointense and 33.3% of patients with T2- hyperintense tumor signal, respectively (P=0.03). Moreover, GH levels decreased by more than 80% from baseline in 81.3% and 33.3% of patients with T2-hypointense and T2-hyperintense tumor signal (P=0.02). A significant tumor volume reduction (≥20%) was observed in 75% of the T2-hypointense and 33.3% of the T2-hyperintense adenomas (P=0.001).

Conclusions

In naive patients with acromegaly, first-line SSA therapy is associated with a better biochemical response and greater tumor shrinkage in T2-hypointense compared to T2-hyperintense adenomas. Therefore, T2-weighted sequences of pituitary MRI can help to classify GH-secreting pituitary adenomas into a T2-hypointense and T2-hyperintense type and, therefore, to identify patients who can better respond to first-line SSA therapy.

Biguanides Exert Antitumoral Actions in Pituitary Tumor Cells Through AMPK-Dependent and -Independent Mechanisms

CONTEXT

Pituitary neuroendocrine tumors (PitNETs) are a commonly underestimated pathology in terms of incidence and associated morbimortality. Currently, an appreciable subset of patients are resistant or poorly responsive to the main current medical treatments [i.e., synthetic somatostatin analogs (SSAs) and dopamine agonists]. Thus, development and optimization of novel and available medical therapies is necessary. Biguanides (metformin, buformin, and phenformin) are antidiabetic drugs that exert antitumoral actions in several tumor types, but their pharmacological effects on PitNETs are poorly known.

OBJECTIVE

We aimed to explore the direct effects of biguanides on key functions (cell viability, hormone release, apoptosis, and signaling pathways) in primary cell cultures from human PitNETs and cell lines. Additionally, we evaluated the effect of combined metformin with SSAs on cell viability and hormone secretion.

DESIGN

A total of 13 corticotropinomas, 13 somatotropinomas, 13 nonfunctioning PitNETs, 3 prolactinomas, and 2 tumoral pituitary cell lines (AtT-20 and GH3) were used to evaluate the direct effects of biguanides on cell viability, hormone release, apoptosis, and signaling pathways.

RESULTS

Biguanides reduced cell viability in all PitNETs and cell lines (with phenformin being the most effective biguanide) and increased apoptosis in somatotropinomas. Moreover, buformin and phenformin, but not metformin, reduced hormone secretion in a cell type-specific manner. Combination metformin/SSA therapy did not increase SSA monotherapy effectiveness. Effects of biguanides on PitNETs could involve the modulation of AMP-activated protein kinase-dependent ([Ca2+]i, PI3K/Akt) and independent (MAPK) mechanisms.

CONCLUSION

Altogether, our data unveil clear antitumoral effects of biguanides on PitNET cells, opening avenues to explore their potential as drugs to treat these pathologies.

Pretreatment with somatostatin analogs does not affect the anesthesiologic management of patients with acromegaly

PURPOSE

Acromegaly may be associated with an increased risk of complex intraoperative management and anesthetic complications. No study addressed whether pretreatment with somatostatin receptor ligands (SRLs) affects anesthesiologic management.

METHODS

We studied 211 consecutive acromegalic patients who had a recorded intraoperative computerized anesthetic record (ICAR) available for analysis. Ninety-six (45.5%) patients were SRL-pretreated while 115 patients were treatment naïve.

RESULTS

Treatment with SRLs reduced mean basal growth hormone level from 23.8 ± 4.2 to 5.9 ± 1.3 µg/L. Normalization of insulin-like growth factor-1 was achieved in 26 patients (27.1%). The frequency of comorbidities at surgery was similar in the two groups. Five patients with difficult intubation were naïve (4.3%) as compared with 5 SRL-pretreated patients (5.2%; P = 1.0). ICAR registration did not show any significant change of intraoperative vital parameters in the two groups of patients as well as in the intraoperative utilization of drugs. Total duration of anesthesia and surgery were similar in the two groups. Four patients with an intraoperative adverse event were naïve (3.5%) as compared with 4 SRL-pretreated patients (4.2%; P = 1.00). Remission of disease occurred in 83 of 114 naïve patients (72.8%) and in 57 of 93 SRL-pretreated patients (61.3%; P = 0.11).

CONCLUSIONS

SRL-pretreatment of patients with acromegaly had no significant impact on intraoperative anesthesiologic management. Despite a better Cormack-Lehane score in SRL-pretreated than in naïve patients, the rate of difficult intubation was similar in both groups. SRL-pretreatment did not affect the rate of surgical remission or complications as well.

The effect of somatostatin analogues on Ki-67 levels in GH-secreting adenomas

PURPOSE

Somatostatin analogues (SSAs) can slow down the growth of neuroendocrine tumors. However, the mechanism remains unclear. Recent studies on patients with acromegaly suggest that SSAs may induce apoptosis, increase autophagy, and decrease cell proliferation of pituitary adenoma. Ki-67-labeling index is a marker of cellular proliferation; therefore, decreased levels are associated with inhibition of proliferation. The aim of this study was to evaluate and compare the Ki-67-labeling index of GH-secreting pituitary adenoma tissues in patients who had undergone pituitary surgery twice due to residual or recurrent tumors and had received SSA treatment between the two surgeries.

METHOD

Thirty acromegaly patients who met the above criteria were identified and evaluated for the demographic, clinical and radiological features retrospectively. Surgical pathology samples of each operation were stained for Ki-67 and evaluated blindly by a staff pathologist specialized in pituitary diseases.

RESULTS

Among patients who received SSA treatment between the first and second operations, the Ki-67 index of the adenoma at the second operation was significantly lower than the Ki-67 index at the first operation. There were no differences in clinical and radiological prognostic markers between the groups with decreased and unchanged Ki-67 index.

CONCLUSION

We concluded that SSA treatment appears to decrease Ki-67 proliferation index independent of tumor features, SSA type, dose and treatment duration. This result suggests that SSA treatment may decrease cellular proliferation, supporting the previous studies.

Acromegaly

Acromegaly is characterized by increased release of growth hormone and, consequently, insulin-like growth factor I (IGF1), most often by a pituitary adenoma. Prolonged exposure to excess hormone leads to progressive somatic disfigurement and a wide range of systemic manifestations that are associated with increased mortality. Although considered a rare disease, recent studies have reported an increased incidence of acromegaly owing to better disease awareness, improved diagnostic tools and perhaps a real increase in prevalence. Acromegaly treatment approaches, which include surgery, radiotherapy and medical therapy, have changed considerably over time owing to improved surgical procedures, development of new radiotherapy techniques and availability of new medical therapies. The optimal use of these treatments will reduce mortality in patients with acromegaly to levels in the general population. Medical therapy is currently an important treatment option and can even be the first-line treatment in patients with acromegaly who will not benefit from or are not suitable for first-line neurosurgical treatment. Pharmacological treatments include somatostatin receptor ligands (such as octreotide, lanreotide and pasireotide), dopamine agonists and the growth hormone receptor antagonist pegvisomant. In this Primer, we review the main aspects of acromegaly, including scientific advances that underlie expanding knowledge of disease pathogenesis, improvements in disease management and new medical therapies that are available and in development to improve disease control.

Efficacy of transsphenoidal surgery for pituitary tumor: A protocol for systematic review

BACKGROUND

This systematic review aims to assess the efficacy and safety of transsphenoidal surgery (TPS) for patients with a pituitary tumor (PT).

METHODS

We will retrieve the following electronic databases for randomized controlled trials or case-control studies to assess the effect and safety of TPS for PT: Cochrane Library, EMBASE, MEDLINE, Cumulative Index to Nursing and Allied Health Literature, Web of Science, Allied and Complementary Medicine Database, and Chinese Biomedical Literature Database. Each database will be retrieved from the inception to December 20, 2018. The entire process consists of the study selection, data collection, methodology quality assessment, data pooled, and meta-analysis performance. The methodology quality will be assessed by using Cochrane risk of bias tool. The data pooled and meta-analysis will be conducted by using RevMan 5.3 software.

RESULTS

This study will evaluate the efficacy and safety of TPS for PT. The primary outcome includes total tumor resection rate. The secondary outcomes consist of quality of life, total tumor resection rate, postoperative complication rate, and the rate of functional tumor hormone levels.

CONCLUSION

The expected results may provide up-to-date evidence of TPS for the treatment of PT.

PROSPERO REGISTRATION NUMBER

PROSPERO CRD42018120194.

International Union of Basic and Clinical Pharmacology. CV. Somatostatin Receptors: Structure, Function, Ligands, and New Nomenclature

Somatostatin, also known as somatotropin-release inhibitory factor, is a cyclopeptide that exerts potent inhibitory actions on hormone secretion and neuronal excitability. Its physiologic functions are mediated by five G protein-coupled receptors (GPCRs) called somatostatin receptor (SST)1-5. These five receptors share common structural features and signaling mechanisms but differ in their cellular and subcellular localization and mode of regulation. SST₂ and SST₅ receptors have evolved as primary targets for pharmacological treatment of pituitary adenomas and neuroendocrine tumors. In addition, SST₂ is a prototypical GPCR for the development of peptide-based radiopharmaceuticals for diagnostic and therapeutic interventions. This review article summarizes findings published in the last 25 years on the physiology, pharmacology, and clinical applications related to SSTs. We also discuss potential future developments and propose a new nomenclature.

Effectiveness and safety of pegvisomant: a systematic review and meta-analysis of observational longitudinal studies

PURPOSE

Acromegaly is a rare disease that often requires drug treatment to achieve control, with pegvisomant being one of the most widely used therapies. In the present paper, we aimed to obtain evidence regarding the effectiveness and safety of pegvisomant by reviewing real-world observational longitudinal studies.

METHODS

A systematic review was performed with a meta-analysis of event rates (95% confidence interval (CI)) using a random effects model. Sensitivity and subgroup analyses were performed (comprehensive meta-analysis 2.0). The systematic review was performed in accordance to preferred reporting items for systematic reviews and meta-analyses, meta-analysis of observational studies in epidemiology, and Cochrane recommendations (PROSPERO register CRD 42017059880). PubMed, Scopus, Web of Science, and SciELO were used to search for literature. Observational studies in patients using pegvisomant for the treatment of acromegaly were included.

RESULTS

Initially, 552 papers were retrieved from the databases; and 31 articles were included in the qualitative analysis and 14 in the quantitative analysis. Eight primary meta-analyses were performed. The overall rate of patients with disease control was of 60.9% (51.8-69.3%; 95% CI). When considering patients under monotherapy, the control rate was 71.7% (64.0-78.4%; 95% CI). Tumor growth was estimated in 7.3% (4.7-11.1%; 95% CI) and elevation of transaminases in 3.0% (1.7-5.2%; 95% CI).

CONCLUSIONS

The real-world data showed that the effectiveness of pegvisomant is not as high as reported in interventional studies. Acromegaly appears to be better controlled when pegvisomant is used as a monotherapy. No serious adverse events were associated with the use of pegvisomant; however, given the high cost of this drug, further studies are required.

A Consensus Statement on acromegaly therapeutic outcomes

The 11th Acromegaly Consensus Conference in April 2017 was convened to update recommendations on therapeutic outcomes for patients with acromegaly. Consensus guidelines on the medical management of acromegaly were last published in 2014; since then, new pharmacological agents have been developed and new approaches to treatment sequencing have been considered. Thirty-seven experts in the management of patients with acromegaly reviewed the current literature and assessed changes in drug approvals, clinical practice standards and clinical opinion. They considered current treatment outcome goals with a focus on the impact of current and emerging somatostatin receptor ligands, growth hormone receptor antagonists and dopamine agonists on biochemical, clinical, tumour mass and surgical outcomes. The participants discussed factors that would determine pharmacological choices as well as the proposed place of each agent in the guidelines. We present consensus recommendations highlighting how acromegaly management could be optimized in clinical practice.

A prospective longitudinal study of Pasireotide in Nelson's syndrome

PURPOSE

Nelson's syndrome is a challenging condition that can develop following bilateral adrenalectomy for Cushing's disease, with high circulating ACTH levels, pigmentation and an invasive pituitary tumor. There is no established medical therapy. The aim of the study was to assess the effects of pasireotide on plasma ACTH and tumor volume in Nelson's syndrome.

METHODS

Open labeled multicenter longitudinal trial in three steps: (1) a placebo-controlled acute response test; (2) 1 month pasireotide 300-600 μg s.c. twice-daily; (3) 6 months pasireotide long-acting-release (LAR) 40-60 mg monthly.

RESULTS

Seven patients had s.c. treatment and 5 proceeded to LAR treatment. There was a significant reduction in morning plasma ACTH during treatment (mean ± SD; 1823 ± 1286 ng/l vs. 888.0 ± 812.8 ng/l during the s.c. phase vs. 829.0 ± 1171 ng/l during the LAR phase, p < 0.0001). Analysis of ACTH levels using a random intercept linear mixed-random effects longitudinal model showed that ACTH (before the morning dose of glucocorticoids) declined significantly by 26.1 ng/l per week during the 28-week of treatment (95% CI - 45.2 to - 7.1, p < 0.01). An acute response to a test dose predicted outcome in 4/5 patients. Overall, there was no significant change in tumor volumes (1.4 ± 0.9 vs. 1.3 ± 1.0, p = 0.86). Four patients withdrew during the study. Hyperglycemia occurred in 6 patients.

CONCLUSIONS

Pasireotide lowers plasma ACTH levels in patients with Nelson's syndrome. A longer period of treatment may be needed to assess the effects of pasireotide on tumor volume.

TRIAL REGISTRATION

Clinical Trials.gov ID, NCT01617733.

Cellular effects of AP102, a somatostatin analog with balanced affinities for the hSSTR2 and hSSTR5 receptors

BACKGROUND

Somatostatin analogs (SSAs) are first-line medical therapy for the treatment of acromegaly and neuroendocrine tumors that express somatostatin receptors (SSTR). Somatostatin suppresses secretion of a large number of hormones through the stimulation of the five SSTR. However, unbalanced inhibition of secretion as observed with the highly potent SSAs pasireotide causes hyperglycaemia mainly by inhibiting insulin secretion. In contrast, AP102 a new SSAs has neutral effect on blood glucose while suppressing GH secretion. Our objective was to establish the cellular effects of AP102 on SSTR2 and SSTR5 that may explain the differences observed between AP102 and other SSAs.

METHODS

We compared the binding and agonist activity of AP102 with somatostatin-14, octreotide and pasireotide in HEK293 cells transfected with human SSTR2 and SSTR5 receptors. SSAs signal transduction effects (cAMP concentrations) were measured in forskolin-treated cells in the presence of SSAs. Proliferation and apoptotic effects were determined and binding assays were performed using ¹²⁵I- somatostatin-14.

RESULTS

AP102 has comparable affinity and agonist effect to octreotide at SSTR2 (IC50's of 112 pM and 244 pM, respectively; EC50's of 230 pM and 210 pM, respectively) in contrast to pasireotide that exhibits a 12-27 fold higher IC50 (3110 pM) and about 5-fold higher EC50 (1097 pM). At SSTR5, AP102 has much higher affinity and stimulating effect than octreotide (IC50's of 773 pM and 16,737 pM, respectively; EC50's of 8526 pM and 26,800 pM), and an intermediate affinity and agonist effect between octreotide and pasireotide. AP102, octreotide and pasireotide have variable anti-proliferative effects on HEK cells transfected with SSTR2 and SSTR5.

CONCLUSION

AP102 is a new SSA that better reduces signaling at SSTR2 than SSTR5 and prevents cell proliferation at both receptors. The euglycaemic effect of AP102 observed in preclinical studies may be related to this intermediate agonistic potency between pasireotide and octreotide at SSTR2 and SSTR5.

Presurgical treatment with somatostatin analogues in growth hormone-secreting pituitary adenomas: A long-term single-center experience

OBJECTIVE

Acromegalic patients with macro- or giant adenomas often had poor prognosis after surgery. Somatostatin analogues (SSAs) show high effectiveness in both tumor shrinkage and serum GH reduction. But the role of SSAs in pre-surgical treatment and the management among macro- and giant adenomas remains controversial.

PATIENTS AND METHODS

A total of 100 acromegalic patients with macro- or giant adenomas that underwent surgery in our institution between January 2010 and December 2016 were enrolled in the current retrospective study. The relationships between several potential parameters and surgical outcomes were further analyzed.

RESULTS

The overall long-term remission rate was 45% accompanied by gross total resection (GTR) rate of 44%. GTR (adjusted OR = 16.346; p = .001) and nadir GH level on OGTT 7 days after surgery (GH-7, adjusted OR = 0.660, p = .039) showed predictive significance for remission after surgery. Tumor size and invasiveness as well as cavernous sinus invasion were risk factors for residual tumor. For invasive macro- or giant adenomas, 6 of 15 patients achieved long-term remission with SSA pre-treatment whereas none of the 18 patients without any preoperative treatment was endocrine controlled.

CONCLUSIONS

Acromegalic patients did not gain more benefits from SSAs pretreatment. But, pre-treatment with SSA could be recommended to patients with invasive macro- or giant adenomas for significant improvement in long-term remission. GTR and GH-7 could be significant predictors in postoperative management of macro- or giant adenomas.

HMGA2 cooperates with either p27kip1 deficiency or Cdk4R24C mutation in pituitary tumorigenesis

We have previously reported a critical role of HMGA proteins in pituitary tumorigenesis since either the Hmga1 or Hmga2 gene overexpression/activation induces the development of mixed growth hormone/prolactin cell pituitary adenomas by activating the E2F transcription factor 1, and then enhancing the G1/S transition of the cell cycle. Consistently, amplification and overexpression of the HMGA2 gene was found in human pituitary prolactinomas. Since impairment of the cell cycle control represents a feature of experimental and human pituitary adenomas, we have investigated the possible synergism between the alterations of other cell cycle regulators, such as p27 deficiency or Cdk4^R24C mutation, with Hmga2 overexpression in pituitary tumorigenesis. Therefore, we crossed the Hmga2/T mice, overexpressing the truncated/active form of the Hmga2 gene, either with the knockout mice for p27^kip1, or with the knockin mice for the Cdk4^R24C mutation, both developing pituitary adenomas. Increased incidence and decreased latency in the development of pituitary lesions appeared in double mutant Hmga2/T;Cdk4^R24C mice, and increased features of invasiveness and atypia were observed in pituitary tumors of both Hmga2/T;p27-ko and Hmga2/T;Cdk4^R24C double mutant mice as compared with single mutant compounds. Interestingly, most of these mice develop pituitary adenomas with high Ki67 index, extrasellar expansion and brain tissue infiltration, representing good mouse models for human aggressive pituitary adenomas. Taken together, the results reported here indicate a cooperation between HMGA2 overexpression and either p27^kip1 or CDK4 impairment in promoting pituitary tumor development and progression.

Novel Somatostatin Receptor Ligands Therapies for Acromegaly

Surgery is considered the treatment of choice in acromegaly, but patients with persistent disease after surgery or in whom surgery cannot be considered require medical therapy. Somatostatin receptor ligands (SRLs) octreotide (OCT), lanreotide, and the more recently approved pasireotide, characterized by a broader receptor ligand binding profile, are considered the mainstay in the medical management of acromegaly. However, in the attempt to offer a more efficacious and better tolerated medical approach, recent research has been aimed to override some limitations related to the use of currently approved drugs and novel SRLs therapies, with potential attractive features, have been proposed. These include both new formulation of older molecules and new molecules. Novel OCT formulations are aimed in particular to improve patients' compliance and to reduce injection discomfort. They include an investigational ready-to-use subcutaneous depot OCT formulation (CAM2029), delivered via prefilled syringes and oral OCT that uses a "transient permeability enhancer" technology, which allows for OCT oral absorption. Another new delivery system is a long-lasting OCT implant (VP-003), which provide stable doses of OCT throughout a period of several months. Finally, a new SRL DG3173 (somatoprim) seems to be more selective for GH secretion, suggesting possible advantages in the presence of hyperglycemia or diabetes. How much these innovations will actually be beneficial to acromegaly patients in real clinical practice remains to be seen.

Prolonged preoperative treatment of acromegaly with Somatostatin analogs may improve surgical outcome in patients with invasive pituitary macroadenoma (Knosp grades 1-3): a retrospective cohort study conducted at a single center

BACKGROUND

This study aimed to investigate preoperative somatostatin analogs (SSAs) treatment on the surgical outcome in patients with acromegaly.

METHODS

An analysis of 358 patients with acromegaly was conducted. The preoperative medical therapy group (81 patients) received SSA treatment for at least 3 months prior to surgery, while the primary surgery group (277 patients) underwent transsphenoidal surgery directly. Follow-up duration was ≥3 months. Tumor invasion was evaluated by magnetic resonance imaging (MRI) and classified according to the Knosp grading system.

RESULTS

Most patients were diagnosed with macroadenoma. Among all patients (Knosp grades 0-4), preoperative SSA therapy did not significantly improve the curative effect of surgery, according to the levels of growth hormone (GH) and/or insulin-like growth factor 1 (IGF-1) markers. In patients with macroadenoma (Knosp grades 1-3), the remission rates were significantly higher in the SSA group compared to the surgery group when considering GH (56.4% vs. 37.3%, P = 0.048) and IGF-1 (43.2% vs. 17.6%, P = 0.004). In the preoperative medical therapy group, long-term use of SSAs (>6 months) led to higher remission rates (GH, 72.2% vs. 51.0%; and IGF-1, 61.1% vs. 29.8%; P = 0.12 and 0.02, respectively].

CONCLUSIONS

The long-term preoperative SSAs treatment may improve the surgical curative rate in acromegalic patients with invasive macroadenomas (Knosp grades 1-3).

Prescription patterns of long-acting somatostatin analogues

Background:

Acromegaly and endocrine tumors are uncommon morbidities that are currently treated with different drugs.

Objective:

To determine the prescription patterns of somatostatin analogues in patients affiliated with the Health System of Colombia.

Methods:

Retrospective cohort study of patients of any age and sex treated with octreotide or lanreotide between January 2011 and August 2015. Socio-demographic, clinical (indications) and pharmacological (comedications) variables were considered. Multivariate analysis was performed with SPSS 23.0.

Results:

We identified 289 patients, with a mean age of 56.6 ± 14.0 years and female predominance (59.5%), who underwent treatment during the 56 months of monitoring. Octreotide was used in 56.1% of cases, followed by lanreotide (43.9%), both at approved doses. We found that 4.5% of subjects changed from one drug to another over the course of therapy, which was associated with being diabetic and receiving insulin (odds ratio: 4.27; 95% confidence interval: 1.23–14.84; p = 0.014). The most common indications were acromegaly (52.2% of cases) followed by neuroendocrine tumors (15.9%). The most common comorbidities were hypertension (39.4% of cases), depression (27.3%), dyslipidemia (23.3%), diabetes mellitus (23.5%) and hypothyroidism (23.5%). Being male (odds ratio: 0.57; 95% confidence interval: 0.35–0.94; p = 0.029) and belonging to the age group between 45 and 65 years (odds ratio: 0.44; 95% confidence interval: 0.21–0.90; p = 0.024) were significantly associated with a lower risk of receiving comedications.

Conclusion:

Somatostatin analogues are being used at recommended doses, especially in patients with acromegaly and neuroendocrine tumors. Variables associated with change in therapy were identified.

Management of aggressive growth hormone secreting pituitary adenomas

Aggressive GH-secreting pituitary adenomas (GHPAs) represent an important clinical problem in patients with acromegaly. Surgical therapy, although often the mainstay of treatment for GHPAs, is less effective in aggressive GHPAs due to their invasive and destructive growth patterns, and their proclivity for infrasellar invasion. Medical therapies for GHPAs, including somatostatin analogues and GH receptor antagonists, are becoming increasingly important adjuncts to surgical intervention. Stereotactic radiosurgery serves as an important fallback therapy for tumors that cannot be cured with surgery and medications. Data suggests that patients with aggressive and refractory GHPAs are best treated at dedicated tertiary pituitary centers with multidisciplinary teams of neuroendocrinologists, neurosurgeons, radiation oncologists and other specialists who routinely provide advanced care to GHPA patients. Future research will help clarify the defining features of "aggressive" and "atypical" PAs, likely based on tumor behavior, preoperative imaging characteristics, histopathological characteristics, and molecular markers.

The role of combination medical therapy in the treatment of acromegaly

PURPOSE

Uncontrolled acromegaly results in approximately 2-fold excess mortality. Pituitary surgery is first-line therapy, and medical treatment is indicated for persistent disease. While cabergoline and pegvisomant are used in select patients, somatostatin receptor ligands (SRLs) remain the cornerstone of medical treatment. Management of patients poorly responsive to SRLs is therefore, challenging. The purpose of this review is to highlight the options for combination medical therapy in the treatment of acromegaly, with an emphasis on efficacy and safety.

METHODS

All original articles/abstracts detailing combination medical therapy in acromegaly were identified from a PubMed search.

RESULTS

Studies reviewed included retrospective and open-label prospective studies. While the combination of SRL and cabergoline was generally well tolerated, a lower baseline insulin-like growth factor-1 (IGF-1) level was the best predictor of efficacy; this combination may be most effective in patients with mildly elevated IGF-1. SRL-pegvisomant combination normalized IGF-1 in the majority of patients; continued efficacy despite individual drug dosing reduction was also reported. The risk of significant liver enzyme elevation was, however, higher than that reported with SRL monotherapy; close monitoring is recommended. Data on pegvisomant-cabergoline combination is limited, but this may be an option in the setting of SRL intolerance. Reports on temozolomide used in combination with other medical therapies in patients with aggressive GH-secreting tumors are also summarized.

CONCLUSION

While more prospective, randomized controlled trials on long-term efficacy and safety are needed, combination medical therapy remains a treatment strategy that should be considered for acromegaly patients poorly responsive to SRLs.

Pasireotide Long-Acting Release Treatment for Diabetic Cats with Underlying Hypersomatotropism

BACKGROUND

Long-term medical management of hypersomatotropism (HS) in cats has proved unrewarding. Pasireotide, a novel somatostatin analogue, decreases serum insulin-like growth factor 1 (IGF-1) and improves insulin sensitivity in cats with HS when administered as a short-acting preparation.

OBJECTIVES

Assess once-monthly administration of long-acting pasireotide (pasireotide LAR) for treatment of cats with HS.

ANIMALS

Fourteen cats with HS, diagnosed based on diabetes mellitus, pituitary enlargement, and serum IGF-1 > 1000 ng/mL.

METHODS

Uncontrolled, prospective cohort study. Cats received pasireotide LAR (6-8 mg/kg SC) once monthly for 6 months. Fructosamine and IGF-1 concentrations, and 12-hour blood glucose curves (BGCs) were assessed at baseline and then monthly. Product of fructosamine concentration and insulin dose was calculated as an indicator of insulin resistance (Insulin Resistance Index). Linear mixed-effects modeling assessed for significant change in fructosamine, IGF-1, mean blood glucose (MBG) of BGCs, insulin dose (U/kg) and Insulin Resistance Index.

RESULTS

Eight cats completed the trial. Three cats entered diabetic remission. Median IGF-1 (baseline: 1962 ng/mL [range 1051-2000 ng/mL]; month 6: 1253 ng/mL [524-1987 ng/mL]; P < .001) and median Insulin Resistance Index (baseline: 812 μmolU/L kg [173-3565 μmolU/L kg]; month 6: 135 μmolU/L kg [0-443 μmolU/L kg]; P = .001) decreased significantly. No significant change was found in mean fructosamine (baseline: 494 ± 127 μmol/L; month 6: 319 ± 113.3 μmol/L; P = .07) or MBG (baseline: 347.7 ± 111.0 mg/dL; month 6: 319.5 ± 113.3 mg/dL; P = .11), despite a significant decrease in median insulin dose (baseline: 1.5 [0.4-5.2] U/kg; 6 months: 0.3 [0.0-1.4] U/kg; P < .001). Adverse events included diarrhea (n = 11), hypoglycemia (n = 5), and worsening polyphagia (n = 2).

CONCLUSIONS AND CLINICAL IMPORTANCE

Pasireotide LAR is the first drug to show potential as a long-term management option for cats with HS.

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.

Expression of Somatostatin Receptor 2 in Somatotropinoma Correlated with the Short-Term Efficacy of Somatostatin Analogues

The expression of somatostatin receptor subtypes (SSTRs) in pituitary growth hormone- (GH-) secreting adenomas may predict the response to somatostatin analogues (SSA). Our aim was to evaluate the value of the immunohistochemical (IHC) scores of 2 subtypes, SSTR2 and SSTR5, in predicting the short-term efficacy of SSA therapy in patients with active acromegaly. Ninety-three newly diagnosed acromegalic patients were included in our study. These patients were categorized into either a SSA-pretreated group (SA, n = 63) or a direct-surgery group (DS, n = 30), depending on whether or not presurgical SSA treatment was received. IHC analysis, using a 12-grade scoring system, with rabbit monoclonal antibodies against SSTR2 and SSTR5, was performed on all adenoma tissues. The reduction of GH, IGF-1, and tumor size after treatment with SSA for 3 months was measured. Compared with that in the DS group, SSTR2 expression was lower in the SA group. Additionally, in the SA group, SSTR2 expression was positively correlated with the reduction of IGF-1 and tumor volume. However, there was no correlation between the SSTR5 score and the efficacy of SSA. In conclusion, the protein expression of SSTR2, but not of SSTR5, is a valuable indicator in predicting biochemical and tumor size response to short-term SSA treatment in acromegalic patients.

The value of an acute octreotide suppression test in predicting short-term efficacy of somatostatin analogues in acromegaly

Predicting the efficacy of long-acting somatostatin analogues (SSA) remains a challenge. We aim to quantitatively evaluate the predictive value of the octreotide suppression test (OST) in short-term efficacy of SSA in active acromegaly. Sixty-seven newly diagnosed acromegaly patients were assessed with OST. Subsequently, all patients were treated with long-acting SSA for 3 months, followed by reassessment. Nine parameters were tested, including GH_n (the nadir GH during OST), ΔGH1 (= [GH_0h-GH_n]/GH_0h, GH_0h was the baseline GH during OST), ΔGH2 (= [GH_m-GH_n]/GH_m, GH_m was the mean GH on day curve), AUC_(0-6h) (the GH area under the curve during OST) , ΔAUC1 (= [GH_0h-AUC_(0-6h)]/GH_0h), ΔAUC2 (=[GH_m-AUC_(0-6h)]/GH_m), AUC_(m-6h) (the GH AUC during OST where GH_m was used instead of GH_0h), ΔAUC1' (=[GH_0h-AUC_(m-6h)]/GH_0h) and ΔAUC2' (=[GH_m-AUC_(m-6h)]/GH_m). The Youden indices were calculated to determine the optimal cutoffs to predict the short-term efficacy of SSA. ΔGH2 more than 86.83%, ΔAUC2 more than -57.48% and ΔAUC2' more than -57.98% provided the best predictors of a good GH response (sensitivity 93.8%, specificity 85.7%). ΔGH2 more than 90.51% provided the best predictor of a good tumor size response (sensitivity 84.8%, specificity 87.5%). The percentage fall of GH_n (ΔGH) was a better predictive parameter than GH_n. OST showed higher efficiency in predicting the efficacy of octreotide LAR than lanreotide SR. In conclusion, OST is a valid tool to predict both GH and tumor size response to short-term efficacy of SSA in acromegaly, especially for octreotide LAR. GH_m is better to be used as basal GH than GH₀ during OST.

Pasireotide Therapy of Multiple Endocrine Neoplasia Type 1-Associated Neuroendocrine Tumors in Female Mice Deleted for an Men1 Allele Improves Survival and Reduces Tumor Progression

Pasireotide, a somatostatin analog, is reported to have anti-proliferative effects in neuroendocrine tumors (NETs). We therefore assessed the efficacy of pasireotide for treating pancreatic and pituitary NETs that develop in a mouse model of multiple endocrine neoplasia type 1 (MEN1). Men1(+/-) mice were treated from age 12 mo with 40 mg/kg pasireotide long-acting release formulation, or PBS, intramuscularly monthly for 9 mo. The Men1(+/-) mice had magnetic resonance imaging at 12 and 21 mo, and from 20 mo oral 5-bromo-2-deoxyuridine for 1 mo, to assess tumor development and proliferation, respectively. NETs were collected at age 21 mo, and proliferation and apoptosis assessed by immunohistochemistry and TUNEL assays, respectively. Pasireotide-treated Men1(+/-) mice had increased survival (pasireotide, 80.9% vs PBS, 65.2%; P < .05), with fewer mice developing pancreatic NETs (pasireotide, 86.9% vs PBS, 96.9%; P < .05) and smaller increases in pituitary NET volumes (pre-treated vs post-treated, 0.803 ± 0.058 mm(3) vs 2.872 ± 0.728 mm(3) [pasireotide] compared with 0.844 ± 0.066 mm(3) vs 8.847 ±1.948 mm(3) [PBS]; P < .01). In addition, pasireotide-treated mice had fewer pancreatic NETs compared with PBS-treated mice (2.36 ± 0.25 vs 3.72 ± 0.32, respectively; P < .001), with decreased proliferation in pancreatic NETs (pasireotide, 0.35 ± 0.03% vs PBS, 0.78 ± 0.08%; P < .0001) and pituitary NETs (pasireotide, 0.73 ±0.07% vs PBS, 1.81 ± 0.15%; P < .0001), but increased apoptosis in pancreatic NETs (pasireotide, 0.42 ± 0.05% vs PBS, 0.19 ± 0.03%; P < .001) and pituitary NETs (pasireotide, 14.75 ± 1.58% vs PBS, 2.35 ± 0.44%; P < .001). Thus, pasireotide increased survival and inhibited pancreatic and pituitary NET growth, thereby indicating its potential as an anti-proliferative and pro-apoptotic therapy.

Pasireotide: a novel treatment for patients with acromegaly

Morbidity and mortality rates in patients with active acromegaly are higher than the general population. Adequate biochemical control restores mortality to normal rates. Now, medical therapy has an increasingly important role in the treatment of patients with acromegaly. Somatostatin receptor ligands (SRLs) are considered the standard medical therapy, either after surgery or as a first-line therapy when surgery is deemed ineffective or is contraindicated. Overall, octreotide and lanreotide are first-generation SRLs and are effective in ~20%-70% of patients. Pegvisomant, a growth hormone receptor antagonist, controls insulin-like growth factor 1 in 65%-90% of cases. Consequently, a subset of patients (nonresponders) requires other treatment options. Drug combination therapy offers the potential for more efficacious disease control. However, the development of new medical therapies remains essential. Here, emphasis is placed on new medical therapies to control acromegaly. There is a focus on pasireotide long-acting release (LAR) (Signifor LAR®), which was approved in 2014 by the US Food and Drug Administration and the European Medicine Agency for the treatment of acromegaly. Pasireotide LAR is a long-acting somatostatin multireceptor ligand. In a Phase III clinical trial in patients with acromegaly (naïve to medical therapy or uncontrolled on a maximum dose of first-generation SRLs), 40 and 60 mg of intramuscular pasireotide LAR achieved better biochemical disease control than octreotide LAR, and tumor shrinkage was noted in both pasireotide groups. Pasireotide LAR tolerability was similar to other SRLs, except for a greater frequency and degree of hyperglycemia and diabetes mellitus. Baseline glucose may predict hyperglycemia occurrence after treatment, and careful monitoring of glycemic status and appropriate treatment is required. A precise definition of patients with acromegaly who will derive the greatest therapeutic benefit from pasireotide LAR remains to be established. Lastly, novel therapies and new potential delivery modalities (oral octreotide) are summarized.