Efficacy and Safety of switching to Pasireotide in Acromegaly Patients controlled with Pegvisomant and Somatostatin Analogues: PAPE extension study

Real-life data of Pasireotide LAR in acromegaly: a long-term follow-up

OBJECTIVE

Pasireotide LAR (PAS-LAR) was released in Italy in 2017 to treat acromegaly patients resistant to SRLs (Somatostatin Receptors Ligands). The long-term follow-up data of PAS-LAR therapy in Italy are limited. This study aimed to evaluate the efficacy and safety of PAS-LAR in acromegaly.

DESIGN

Patients with acromegaly in PAS-LAR treatment were enrolled in three tertiary Italian endocrinological centers and evaluated by a retrospective observational real-life multicentre study.

METHODS

Patients have been studied before (baseline) and 1, 6, 12, 24 and > 36 months after PAS-LAR start. Clinical, biochemical, and pituitary magnetic resonance data were collected, along with information on adverse events. Acromegaly disease activity was classified according to the IGF-1 index (normal value < 1.0).

RESULTS

Fifty patients (female 23) were enrolled. PAS-LAR treatment (mean follow-up 24 ± 16 months) significantly decreased IGF-1 levels (IGF-1 index baseline vs last visit: 1.9 ± 0.6 vs 1.2 ± 0.6, p < 0.0001). At the last visit, 67% of patients had controlled disease, and 44% showed a decrease in tumor volume. Clinical and biochemical efficacy was observed as early as after 1-month of PAS-LAR treatment (IGF-1 index baseline vs 1-month: 1.9 ± 0.6 vs 1.4 ± 0.7, p < 0.0001). Also, 50% of patients referred headache improvement or disappearance. Fifteen patients discontinued PAS-LAR due to failure of treatment and poor glycaemic control. The prevalence of diabetes increased from 33% at the baseline to 54% at the last visit (p = 0.0072).

CONCLUSION

In real-life settings, PAS-LAR significantly decreases symptoms, IGF-1 levels, and the size of adenoma in patients with acromegaly resistant to SRLs. Beneficial effects may occur early after the first injection.

Medical treatment of functional pituitary adenomas, trials and tribulations

CONTEXT

Functioning pituitary adenomas (FPAs) include most frequently prolactinomas, somatotroph or corticotroph adenomas, while thyrotroph and gonadotroph adenomas are very rare. Despite their benign histological nature (aggressive tumors are rare and malignant ones exceptional), FPAs could cause significant morbidity and increased mortality due to complications associated with hormonal excess syndromes and/or mass effect leading to compression of adjacent structures. This mini review will focus on the increasing role of medical therapy in the multimodal treatment, which also includes transsphenoidal surgery (TSS) and radiotherapy.

EVIDENCE SYNTHESIS

Most patients with prolactinomas are treated only with medications, but surgery could be considered for some patients in a specialized pituitary center, if higher chances of cure. Dopamine agonists, especially cabergoline, are efficient in reducing tumor size and normalizing prolactin. TSS is the first-line treatment for all other FPAs, but most patients require complex adjuvant treatment, including a combination of therapeutic approaches. Medical therapy is the cornerstone of treatment in all patients after unsuccessful surgery or when surgery cannot be offered and includes somatostatin receptor ligands and dopamine agonists (almost all FPAs), growth hormone receptor antagonists (acromegaly), adrenal steroidogenesis inhibitors and glucocorticoid receptor blockers (Cushing's disease). Novel medical treatments, especially for acromegaly and Cushing's disease are under research.

CONCLUSIONS

An enlarged panel of effective drugs available with increased knowledge of predictive factors for response and/or adverse effects will enhance the possibility to offer a more individualized treatment. This would not only improve disease control and prognosis, but also quality of life.

Assessment of multimodal treatment options in recurrent and persistent acromegaly: a systematic review and meta-analysis

PURPOSE

In patients with acromegaly, secondary treatment options in cases of hormonal non-remission or tumor progression include repeat transsphenoidal surgery (TSS), radiation-based treatment (RT), or medical therapy (MT). In this study, we aim to evaluate the clinical effectiveness of various second-line treatment options for acromegaly.

METHODS

Using the PRISMA guideline, a systematic review was performed by searching MEDLINE (PubMed), Web of Science, Scopus, and Cochrane electronic bibliographic databases from conception to the end of 2022. Outcomes of interest included hormonal remission rate, complications, and mortality associated with each treatment modality for refractory acromegaly.

RESULTS

A total of 79 studies including 3,208 refractory acromegaly patients (44.90% males) were analyzed, with a mean patient age of 43.89 years. There was a statistically significant difference between various therapeutic modalities in terms of remission rate, with MT offering the highest remission rate (62.55%), followed by RT (50.15%) and TSS (37.39%). Subgroup analysis of radiotherapeutic and medical modalities did not show a significant difference in remission rate between different kinds of sub-modalities in each treatment approach. Recurrence following secondary treatment was not different in patients treated with reoperation TSS compared to other modalities.

CONCLUSIONS

The management of persistent and recurrent acromegaly optimally requires a multimodal approach. In different scenarios of refractory acromegaly based on previous treatment, secondary treatments may vary in terms of remission rate and complications. Medical agents provide considerable effectiveness as a second-line therapy for recurrent or persistent disease. In selected cases, however, reoperation still provides an opportunity for cure or freedom from medications. The findings of this study may help clinicians to prioritize varying options involved in this multifaceted decision-making process.

Management of pasireotide-induced hyperglycemia in patients with acromegaly: An experts' consensus statement

Pasireotide is a somatostatin analogue for the treatment of acromegaly, a chronic condition caused by excess growth hormone. Despite the therapeutic benefits of pasireotide as a second-line treatment for inadequately controlled acromegaly, a major concern is its hyperglycemic side-effect. Here, we provide guidance on how to select appropriate patients with acromegaly for treatment with pasireotide. We summarize baseline characteristics of patients at high risk for pasireotide-associated hyperglycemia and recommend a monitoring strategy based on the risk profile. Self-monitoring of blood glucose levels (SMBG), measurements of fasting plasma glucose (FPG), postprandial plasma glucose (PPG) and regular HbA1c measurements are the foundation of our proposed monitoring approach. The pathophysiology of pasireotide-induced hyperglycemia involves decreased secretion of the incretin hormones GIP (glucose-dependent insulinotropic polypeptide) and GLP-1 (glucagon-like peptide-1). Our expert recommendations address the specific pathophysiology of pasireotide-induced hyperglycemia by recommending the incretin-based therapeutics dipeptidyl peptidase-4 inhibitors (DPP-4i) and glucagon-like peptide-1 receptor agonists (GLP-1 RA) in all appropriate patients as an alternative to first-line monotherapy with metformin. Furthermore, we emphasize the importance of adequate control of acromegaly, excellent diabetes education, nutrition and lifestyle guidance and advise to consult expert diabetologists in case of uncertainty in the management of patients with hyperglycemia under pasireotide.

Current role of pasireotide in the treatment of acromegaly

"First-generation" somatostatin receptor agonists (SSTRAs) octreotide and lanreotide are the most commonly used first-line pharmacological therapy for patients with acromegaly. A subset of patients respond only partially or not at all to the first-generation SSTRA, necessitating the use of additional pharmacological agents or other modes of therapy. Pasireotide is a "second-generation" SSTRA that has multi-receptor activity. Prospective studies have shown promise in the use of pasireotide in patients with poor response to first-generation SSTRA. Here we elucidate the molecular pathways of resistance to first-generation SSTRA, the mechanism of action, pre-clinical and clinical evidence of the use of pasireotide in patients having incomplete / lack of response to first-generation SSTRA. We also discuss the clinical, pathological, and radiological markers predicting response to pasireotide, and the difference in side-effect profiles of pasireotide, compared to first-generation SSTRA.

Efficacy and Safety of Pegvisomant in the Treatment of Acromegaly

Pegvisomant, the first and currently only clinically available growth hormone receptor antagonist, is an effective therapeutic option for the medical treatment of acromegaly, a rare disorder characterized by excessive growth hormone secretion. With now over 20 years of real world experience, its safety and efficacy is well-established. However, several aspects of its clinical use are still controversially discussed. The high cost of pegvisomant has limited its use in several countries, and recent studies have reported a lower efficacy than the initial clinical trials. A reported increase in tumor volume under therapy varies between studies and has been attributed to either actual growth or re-expansion after cessation of somatostatin receptor ligand therapy. Furthermore, different combinations of pegvisomant and other therapeutic agents aiming at reduction of acromegaly disease activity have been proposed to increase or retain effectiveness while lowering side effects and cost. This review aims to assess current clinical data on the safety and efficacy of pegvisomant while also addressing controversies surrounding its use.

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.

Impairment in insulin secretion without changes in insulin resistance explains hyperglycemia in patients with acromegaly treated with pasireotide LAR

Objective

Pasireotide is a second-generation somatostatin receptor ligand (SRL) used for treating acromegaly. Its clinical use is limited by adverse effects on glucose homeostasis. The aim of this study was to evaluate longitudinal changes in beta-cell function and insulin sensitivity associated with pasireotide in patients not controlled by first-generation SRLs.

Design

We performed a retrospective study.

Methods

The efficacy (growth hormone (GH)/insulin-like growth factor (IGF-1) concentrations; tumor size) and effect on glucose homeostasis were analyzed in 33 patients. Longitudinal data on oral glucose tolerance tests were available before, shortly (mean ± s.d., 6.1 ± 3.8 months) and long term (24.4 ± 11.1 months) after initiation of pasireotide in 14 patients. Insulin secretion (insulinogenic index; disposition index) and insulin sensitivity were calculated by validated indices.

Results

Pasireotide-induced diabetes occurred in 12 patients (36%). It was mediated by impaired insulin secretion, which occurred shortly after initiation of treatment and then remained stable on long term (insulinogenic index, median (min; max), 80 (12; 542) vs 16 (6.4; 101) vs 25 (3.7; 396) pmol/mmol, respectively; P = 0.028; disposition index, 1.45 (0.42; 4.88) vs 0.53 (0.17; 2.63) vs 0.60 (0.22; 1.71), respectively; P = 0.024). No significant changes in insulin sensitivity were observed, despite a marked reduction of GH/IGF-1 concentrations. Older age and a worse glycemic control at baseline were the strongest predictors for hyperglycemia and the need for antidiabetic treatment.

Conclusion

Worsening of glycemic control during pasireotide therapy is caused by an impaired insulin secretion, whereas insulin sensitivity is not affected. These findings might be important for the choice of antidiabetic treatment for pasireotide-induced hyperglycemia.

Significance statement

Pasireotide, a second-generation SRL used for treating acromegaly, may be associated with glucose metabolism impairment. In a retrospective study of 33 patients, we observed that treatment with pasireotide was associated with normalization of serum IGF-1 in almost 60% of patients, but one-third of patients developed diabetes. In the patients who stopped pasireotide because of hyperglycemia, HbA1c promptly decreased. Longitudinal data in 14 patients show that diabetes is mediated by impaired insulin secretion, which occurred shortly and then remained stable on long term, while no significant changes in insulin sensitivity were observed, despite a marked reduction of GH/IGF-1 concentrations. Older age and a worse glycemic control at baseline were the strongest predictors for hyperglycemia.

Second line treatment of acromegaly: Pasireotide or Pegvisomant?

Acromegaly is a chronic disease with an increased mortality in case of persistently active disease. The treatment of acromegaly is mainly based on the surgical resection of the GH secreting pituitary tumor and, in cases with persistent disease, on the medical therapy with first generation somatostatin analogues (first gen-SSAs). Data from national registries, meta-analysis and epidemiology studies showed that 24%-65% of acromegaly patients treated with first gen-SSA did not reach the control of disease, requiring second line therapies, as the second gen-SSAs and the GH receptor antagonist. According to the high efficacy of these treatments and their molecular mechanisms of action, the choice of second line therapies should be personalized. In this review, we summarize the evidence on clinical, molecular and morphological aspects that may predict the response to second line therapies, in order to integrate and translate in the clinical practice for a patient-tailored therapeutic approach.

Acromegaly: pathogenesis, diagnosis, and management

Growth hormone-secreting pituitary adenomas that cause acromegaly arise as monoclonal expansions of differentiated somatotroph cells and are usually sporadic. They are almost invariably benign, yet they can be locally invasive and show progressive growth despite treatment. Persistent excess of both growth hormone and its target hormone insulin-like growth factor 1 (IGF-1) results in a wide array of cardiovascular, respiratory, metabolic, musculoskeletal, neurological, and neoplastic comorbidities that might not be reversible with disease control. Normalisation of IGF-1 and growth hormone are the primary therapeutic aims; additional treatment goals include tumour shrinkage, relieving symptoms, managing complications, reducing excess morbidity, and improving quality of life. A multimodal approach with surgery, medical therapy, and (more rarely) radiation therapy is required to achieve these goals. In this Review, we examine the epidemiology, pathogenesis, diagnosis, complications, and treatment of acromegaly, with an emphasis on the importance of tailoring management strategies to each patient to optimise outcomes.

Clinical Management of Acromegaly: Therapeutic Frontiers and New Perspectives for Somatostatin Receptor Ligands (SRLs)

Somatostatin receptor ligands (SRLs) represent a true milestone in the medical therapy for acromegaly. The first-generation SRLs (FG-SRLs), octreotide and lanreotide, have demonstrated good efficacy in disease control and tumor shrinkage, and are still considered first-line medical therapies. The development of long-acting release (LAR) formulations has certainly improved the therapeutic tolerability of these drugs, although many patients still experience therapy-related burden. As such, new formulations have recently been developed to improve adherence and therapeutic efficacy and more solutions are on the way. In the case of FG-SRL-resistant disease, pasireotide, the only second generation SRL currently available, demonstrated superiority in disease control and tumor shrinkage compared to FG-SRLs. However, its use in clinical practice is still limited due to concern for impairment in glucose homeostasis. In this review, we discuss the news about the present and future role of SRLs in acromegaly, exploring the therapeutical frontiers of this drug class. Moreover, we provide practical guidance on the use of pasireotide, based on the data in the literature and our clinical experience.

Pasireotide-a novel somatostatin receptor ligand after 20 years of use

Pasireotide, a novel multireceptor-targeted somatostatin receptor ligand (SRL) is characterized by a higher affinity to somatostatin receptor type 5 than type 2, unlike first-generation SRLs. Because of the broader binding profile, pasireotide has been suggested to have a greater clinical efficacy in acromegaly than first-generation SRLs and to be efficacious in Cushing's disease. The consequence of this binding profile is the increased blood glucose level in some patients. This results from the inhibition of both insulin secretion and the incretin effect and only a modest suppression of glucagon. A monthly intramuscular formulation of long-acting release pasireotide has been approved for both acromegaly and Cushing's disease treatment. This review presents data on the efficacy and safety of pasireotide treatment mostly in patients with acromegaly and Cushing's disease. Moreover, other possible therapeutic applications of pasireotide are mentioned.

Approach to the Patient With Treatment-resistant Acromegaly

Although most tumors in patients with acromegaly are benign and are cured or controlled by surgery and/or first-generation somatostatin receptor ligands therapy, some can behave more aggressively and are resistant to these standard therapies. Acromegaly, if left untreated, is a rare and chronic disorder, commonly caused by a GH-producing pituitary adenoma and is associated with significant comorbidities and an increased mortality. Transsphenoidal surgery is considered the mainstay of acromegaly management, but medical therapy has an increasingly important role. However, disease activity is not fully controlled in a significant number of patients treated with surgery and/or high-dose first-generation somatostatin receptor ligand monotherapy. In these circumstances, therefore, repeated surgery, second-line medical therapy, and radiotherapy, alone or combined as multimodal therapeutic strategies should be considered, in a patient-centered perspective.

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.

Glucose metabolism outcomes in acromegaly patients on treatment with pasireotide-LAR or pasireotide-LAR plus Pegvisomant

INTRODUCTION

Disorders of glucose metabolism are a serious acromegaly comorbidity and may be differently impacted by medical treatments of acromegaly. In this retrospective longitudinal multicenter study, we investigated the outcome of glucose metabolism and its predictors in patients treated with Pasireotide LAR (PAS-LAR) alone or in combination with Pegvisomant (PAS-LAR + Peg-V).

SUBJECTS AND METHODS

Acromegaly patients treated continously with PAS-LAR or PAS-LAR + Peg-V for at least 6 months.

RESULTS

Forty patients (25 females, 15 males) were enrolled. At last visit, 27/40 patients (67.5%) reached biochemical control of acromegaly. Overall, glucose metabolism improved in 3 (all in PAS-LAR + Peg-V; 7.5%), worsened in 26 (65%) and remained unchanged in 11 patients (27.5%). Glucose metabolism worsened in 25 patients (73.5%) treated with PAS-LAR and in a single patient (16.7%) treated with PAS-LAR + Peg-V (p < 0.001). Among patients treated with Pas-LAR alone, GH at baseline was higher in those with worsening of glucose metabolism (p = 0.04) as compared to those with stable glucose status. A significantly higher reduction of HbA1c was observed in patients treated with PAS-LAR + Peg-V, as compared with those treated with PAS-LAR alone (p = 0.005).

CONCLUSIONS

Our data confirmed that glucose metabolism in patients treated with PAS-LAR is often worsened, and may be predicted by entity of baseline GH hypersecretion and by the dose of PAS-LAR. Moreover, our data, although limited by small numbers, may suggest that the combination treatment PAS-LAR + Peg-V can improve glucose homeostasis in selected patients.

A Pituitary Society update to acromegaly management guidelines

Guidelines and consensus statements ensure that physicians managing acromegaly patients have access to current information on evidence-based treatments to optimize outcomes. Given significant novel recent advances in understanding acromegaly natural history and individualized therapies, the Pituitary Society invited acromegaly experts to critically review the current literature in the context of Endocrine Society guidelines and Acromegaly Consensus Group statements. This update focuses on how recent key advances affect treatment decision-making and outcomes, and also highlights the likely role of recently FDA-approved therapies as well as novel combination therapies within the treatment armamentarium.

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.

The Effect of 6 Months' Treatment With Pasireotide LAR on Glucose Metabolism in Patients With Resistant Acromegaly in Real-World Clinical Settings

OBJECTIVE

The aim of the study was to evaluate glucose metabolism, as measured by glycated hemoglobin (HbA1c) levels and the need for antidiabetic medical treatment, in patients with acromegaly resistant to first-generation somatostatin receptors ligands (SRLs) treated with pasireotide long-acting release (LAR) in real-world clinical practice. Biochemical control of acromegaly, as measured by growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels, was also assessed.

STUDY DESIGN

Two-center retrospective cohort of consecutive patients with acromegaly treated with first-generation SRLs at maximum doses, who had not achieved biochemical disease control. After SRLs were discontinued, patients were given pasireotide LAR 40 mg i.m. every 28 days. The dose was increased to 60 mg i.m. in patients for whom adequate control was not achieved after 3 months. Patients were given dietary and lifestyle advice, and antihyperglycemic treatment was modified as needed.

MAIN OUTCOME MEASURES

Biochemical disease control parameters (GH and IGF-1 concentration), as well as HbA1c level at baseline and after 6 months.

RESULTS

In total, 39 patients with acromegaly were enrolled. GH concentration decreased (Δ_me =-1.56 µg/L, range -21.38-3.62, p <0.001) during 6 months of pasireotide LAR treatment. A worsening of metabolic status was observed, with an increase of median HbA1c (Δ_me =0.40%, range -0.20%-2.30%, p <0.001), and antihyperglycemic treatment intensification in 23 (59.0%) patients. The median decline in IGF-1 concentration was: -283.0 µg/L, range -682.7-171.6, p <0.001. IGF-1 reached the age- and gender-specific upper level of normal in 23 (59%) patients.

CONCLUSIONS

Pasireotide LAR is an effective therapeutic option in patients with acromegaly refractory to first-generation SRLs. However, this therapy may result in pasireotide LAR-associated hyperglycemia, which requires early and aggressive antidiabetic medical therapy to prevent glucose homeostasis alterations.

Novel therapies for acromegaly

Acromegaly is a systemic disease associated with increased morbidity and mortality. Most of these comorbidities can be prevented or delayed with adequate disease treatment. Although three modalities of treatment (surgery, medical treatment, and radiotherapy) are available and new drugs were approved in the last decades, there are still some patients that maintain disease activity despite treatment. Therefore, there is a need for novel therapies for acromegaly and for that purpose new formulations of currently used drugs and also new drugs are currently under study. In this review, we summarize the novel therapies for acromegaly.

Somatostatin receptor expression and patients' response to targeted medical treatment in pituitary tumors: evidences and controversies

BACKGROUND

Somatostatin receptors (SSTs) are widely co-expressed in pituitary tumors. SST₂ and SST₅ are the most represented SST subtypes. First-generation somatostatin receptor ligands (SRLs) mainly target SST₂, while pasireotide, a multi-receptor ligand, shows high binding affinity for both SST₅ and SST₂. Therefore, SRLs are routinely used as medical treatment for GH-, TSH-, and ACTH-secreting pituitary tumors.

METHODS

Critical revision of literature data correlating SST expression with patients' response to SRLs.

RESULTS

SST₂ expression in somatroph tumors directly correlates with GH and IGF-1 decrease after first-generation SRL treatment. SST₂ immunohistochemistry represents a valuable tool to predict biochemical response to first-generation SRLs in acromegalic patients. Pasireotide seems to exert its biological effects via SST₂ in unselected patients. However, in those subjects resistant to first-generation SRLs, harbouring tumors with negligible SST₂ expression, pasireotide can act throughout SST₅. More than somatotroph tumors, TSH-omas represent the paradigm of tumors showing a satisfactory response to SRLs. This is probably due to the high SST₂ expression observed in nearly 100% of cases, as well as to the balanced amount of SST₅. In corticotroph tumors, pasireotide mainly act via SST₅, although there is a need for translational studies correlating its efficacy with SST expression in this peculiar tumor histotype.

CONCLUSIONS

The assumption "more target receptor, more drug efficacy" is not straightforward for SRLs. The complex pathophysiology of SSTs, and the technical challenges faced to translate research findings into clinical practice, still need our full commitment to make receptor evaluation a worthwhile procedure for individualizing treatment decisions.

Emerging drugs for the treatment of acromegaly

INTRODUCTION

Acromegaly is a disease characterized by elevated growth hormone (GH) and insulin-like growth factor 1 (IGF-1) levels. Surgery is the only curative treatment, while medical therapies are administered life-long. To date, almost 30% of patients treated with the currently available medical therapies do not achieve biochemical control.

AREAS COVERED

This review focuses on new drugs in development for acromegaly. In detail, we provide an overview of the new molecules designed to improve disease control rate (such as novel somotostatin receptor ligands and antisense oligonucleotides), as well as the new formulations of existing medications aiming to improve patients' compliance (e.g. oral or long-acting subcutaneous octreotide).

EXPERT OPINION

The constant progresses in the medical treatment of acromegaly could lead to an individualized therapy based on tumor, as well as patient's characteristics. Besides disease control, patient's need represents a major target of medical treatment in chronic diseases such as acromegaly, in order to improve compliance to therapy and patients' quality of life.

Combined therapy of somatostatin analogues with pegvisomant for the treatment of acromegaly: a meta-analysis of prospective studies

BACKGROUND

Acromegaly is a rare, chronic and severe disease. Drug therapy including somatostatin analogues (SAs), dopamine receptor agonists and growth hormone receptor antagonists (pegvisomant, PEG) are commonly used to treat patients who do not respond to surgery. The use of combination therapy with PEG and SAs has become more common over the last decade. We performed this study to accurately evaluate the effect of combination therapy of SAs with PEG on acromegalic patients.

METHODS

PubMed, EMBASE, The Cochrane Library, ClinicalTrials.gov, Scopus, Web of Science, Chinese Biomedical Literature Database and Trip database were searched for relevant studies. Prospective clinical trials treating acromegaly with the co-administration of SAs and PEG were included. We performed a meta-analysis by using Stata 12.1. Sensitivity analysis was conducted to explore heterogeneity.

RESULTS

Nine studies were included in this meta-analysis. The overall rate of serum insulin-like growth factor 1 (IGF-1) normalization was 66% (95% CI: 52-78%; I² = 62.59%). The combination therapy did not significantly change patients' fasting plasma glucose (ES: 0.011 mmol*L^- 1; 95% CI: - 0.374 to 0.397 mmol*L^- 1; P = 0.954) or glycosylated haemoglobin (ES: - 0.074%; 95% CI: - 0.166 to 0.315%; P = 0.544) while decreasing the fasting plasma insulin (ES: - 21.487 pmol*L^-1; 95% CI: - 35.713 to - 7.260 pmol*L^-1; P = 0.003). Elevation of liver enzyme levels was found in 14% (95% CI: 8 to 21%) of the patients. There was no significant difference for serious adverse events and treatment discontinuation due to adverse event between SAs monotherapy group and combination therapy group.

CONCLUSIONS

Combined therapy of SAs and PEG effectively normalized IGF-1 levels in most of the patients whose IGF-1 level was greater than the upper limit of normal after high dose SAs monotherapy. The therapy also decreased significantly FPI levels with a neutral effect on glucose parameters in acromegaly patients. Moreover, elevated liver enzyme levels were observed in a small number of patients, which suggests a need for liver function monitoring.

TRIAL REGISTRATION

We have our protocol registered in PROSPERO. (Registration number: CRD42019115549 ).

Soluble Klotho: a possible predictor of quality of life in acromegaly patients

PURPOSE

Although quality of life (QoL) is improved in patients with acromegaly after disease control, QoL correlates only weakly with traditional biomarkers. Our objective is to investigate a potential relation between the new serum biomarker soluble Klotho (sKlotho), GH and insulin-like growth factor 1 (IGF-1) levels, and QoL.

METHODS

In this prospective cohort study, we investigated 54 acromegaly patients biochemically well-controlled on combination treatment with first-generation somatostatin receptor ligands (SRLs) and pegvisomant (PEGV) at baseline and 9 months after switching to pasireotide LAR (PAS-LAR; either as monotherapy, n = 28; or in combination with PEGV, n = 26). QoL was measured by the Patient-Assessed Acromegaly Symptom Questionnaire (PASQ) and Acromegaly Quality of Life (AcroQoL) questionnaire.

RESULTS

Switching to PAS-LAR treatment significantly improved QoL without altering IGF-1 levels. QoL did not correlate with GH or IGF-1 levels, but sKlotho correlated with the observed improvements in QoL by the AcroQoL global (r = -0.35, p = 0.012) and physical subdimension (r = -0.34, p = 0.017), and with PASQ headache (r = 0.28, p = 0.048), osteoarthralgia (r = 0.46, p = 0.00080) and soft tissue swelling score (r = 0.29, p = 0.041). Parallel changes in serum sKlotho and IGF-1 (r = 0.31, p = 0.023) suggest sKlotho and IGF-1 to be similarly dependent on GH. Comparing the PAS-LAR combination therapy and the monotherapy group we did not observe a significant difference in improvement of QoL.

CONCLUSIONS

Patients experienced improved QoL during PAS-LAR, either as monotherapy or in combination with PEGV. Soluble Klotho concentrations appear to be a useful marker of QoL in acromegaly patients but the underlying mechanisms remain to be investigated.

Pasireotide for acromegaly: long-term outcomes from an extension to the Phase III PAOLA study

OBJECTIVE

In the Phase III PAOLA study (clinicaltrials.gov: NCT01137682), enrolled patients had uncontrolled acromegaly despite ≥6 months of octreotide/lanreotide treatment before study start. More patients achieved biochemical control with long-acting pasireotide versus continued treatment with octreotide/lanreotide (active control) at month 6. The current work assessed the extent of comorbidities at baseline and outcomes during a long-term extension.

DESIGN/METHODS

Patients receiving pasireotide 40 or 60 mg at core study end could continue on the same dose in an extension phase if biochemically controlled or receive pasireotide 60 mg if uncontrolled. Uncontrolled patients on active control were switched to pasireotide 40 mg, with the dose increased at week 16 of the extension if still uncontrolled (crossover group). Efficacy and safety are reported to 304 weeks (~5.8 years) for patients randomized to pasireotide (core + extension), and 268 weeks for patients in the crossover group (extension only).

RESULTS

Almost half (49.5%; 98/198) of patients had ≥3 comorbidities at core baseline. During the extension, 173 patients received pasireotide. Pasireotide effectively and consistently reduced GH and IGF-I levels for up to 5.8 years' treatment; 37.0% of patients achieved GH <1.0 µg/L and normal IGF-I at some point during the core or extension. Improvements were observed in key symptoms. The long-term safety profile was similar to that in the core study; 23/173 patients discontinued treatment because of adverse events.

CONCLUSIONS

In this patient population with a high burden of comorbid illness, pasireotide was well tolerated and efficacious, providing prolonged maintenance of biochemical control and improving symptoms.

Octreotide-Resistant Acromegaly: Challenges and Solutions

Acromegaly is a rare and severe disease caused by an increased and autonomous secretion of growth hormone (GH), thus resulting in high circulating levels of insulin-like growth factor 1 (IGF-1). Comorbidities and mortality rate are closely related to the disease duration. However, in most cases achieving biochemical control means reducing or even normalizing mortality and restoring normal life expectancy. Current treatment for acromegaly includes neurosurgery, radiotherapy and medical therapy. Transsphenoidal surgery often represents the recommended first-line treatment. First-generation somatostatin receptor ligands (SRLs) are the drug of choice in patients with persistent disease after surgery and are suggested as first-line treatment for those ineligible for surgery. However, only about half of patients treated with octreotide (or lanreotide) achieve biochemical control. Other available drugs approved for clinical use are the second-generation SRL pasireotide, the dopamine agonist cabergoline, and the GH-receptor antagonist pegvisomant. In the present paper, we revised the current literature about the management of acromegaly, aiming to highlight the most relevant and recent therapeutic strategies proposed for patients resistant to first-line medical therapy. Furthermore, we discussed the potential molecular mechanisms involved in the variable response to first-generation SRLs. Due to the availability of different medical therapies, the choice for the most appropriate drug can be currently based also on the peculiar clinical characteristics of each patient.

Random Gh and Igf-I levels after transsphenoidal surgery for acromegaly: relation with long-term remission

PURPOSE

To evaluate the role of IGF-I and random GH measurements 3 months after transsphenoidal surgery (TSS) in predicting long-term remission in acromegaly patients.

METHODS

Retrospective analysis of 54 acromegaly patients who underwent TSS with the same neurosurgery team. Random GH and IGF-I values evaluated 3 months after TSS were related to long-term outcomes. The initiation of adjuvant therapy at any time defined surgical failure.

RESULTS

At 3 months, 14 (25.9%) patients had controlled disease (CD; normal IGF-I and GH < 1.0 µg/L), 25 (46.3%) had uncontrolled disease (UD; high IGF-I and GH), and 15 (27.8%) had biochemical discrepancies (BD): 12 BDI (normal IGF-I + GH ≥ 1.0 μg/L) and 3 BDII (high IGF-I + GH < 1.0 μg/L). All patients of the CD group, 2 of the UD, 11 of the BDI, and 2 of the BDII, progressed with long-term remission and had IGF-I ≤ 1.25-fold the Upper Limit of Normal (ULN), in contrast with all cases of surgical failure where IGF-I was ≥1.3-fold ULN. Only one patient with normal IGF-I had recurrence, resulting in 100% sensitivity and 96% specificity of post-surgical IGF-I ≤ 1.25-fold ULN to predict long-term remission, observed in 54% of our cohort. Post-surgical random GH ≥ 1.7 µg/L was the best cutoff to identify surgical failure, but its accuracy to predict long-term outcomes was limited.

CONCLUSIONS

IGF-I levels ≤ 1.25-fold ULN 3 months after TSS was the best guide for long-term remission in acromegaly patients with both initial surgical failure and discrepant biochemical results.

The position of combined medical treatment in acromegaly

Advances in combination medical treatment have offer new perspectives for acromegaly patients with persistent disease activity despite receiving the available medical monotherapies. The outcomes of combination medical treatment may reflect both additive and synergistic effects. This review focuses on combination medical treatment and its current position in acromegaly, based on clinical studies evaluating the efficacy and safety of combined medical treatment(s) and our own experiences with combination therapy. Arch Endocrinol Metab. 2019;63(6):646-52.

How to Position Pasireotide LAR Treatment in Acromegaly

CONTEXT

Pasireotide long-acting release (LAR) is a somatostatin multireceptor ligand, and in the current consensus criteria pasireotide LAR is considered the second-line medical treatment for acromegaly. We present in this article our recommendations to define the position of pasireotide LAR in the treatment of acromegaly and provide recommendations for the management of pasireotide-induced hyperglycemia.

EVIDENCE ACQUISITION

Our recommendations are based on our experiences with the pasireotide LAR and pegvisomant (PEGV) combination study and the available basic or clinical articles published in peer-reviewed international journals on pasireotide LAR and acromegaly.

EVIDENCE SYNTHESIS

In accordance with the current consensus criteria, we recommend pasireotide LAR monotherapy as a second-line therapy in young patients who show tumor growth during first-generation somatostatin receptor ligand (SRL) therapy and in patients who show tumor growth during PEGV therapy. In addition, we recommend pasireotide LAR monotherapy in patients with headache not responsive to first-generation SRL therapy and in patients who experience side effects or are intolerant to PEGV monotherapy. In contrast to the current consensus criteria, we recommend considering combination therapy with pasireotide LAR and PEGV as third-line treatment in patients without diabetes at low PEGV dosages (≤80 mg/week) and in patients with tumor growth or symptoms of active acromegaly during first-generation SRL and PEGV combination therapy. With respect to pasireotide-induced hyperglycemia, we recommend a more liberal strategy of blood glucose monitoring during pasireotide treatment.

CONCLUSIONS

In contrast to the current consensus criteria, we recommend a more reluctant use of pasireotide LAR therapy for the treatment of acromegaly.

Functioning Pituitary Adenomas - Current Treatment Options and Emerging Medical Therapies

Pituitary adenomas are benign tumours comprising approximately 16% of all primary cranial neoplasms. Functioning pituitary adenomas (prolactinomas, somatotroph, corticotroph, thyrotroph and rarely gonadotroph adenomas) cause complex clinical syndromes and require prompt treatment to reduce associated morbidity and mortality. Treatment approaches include transsphenoidal surgery, medical therapy and radiation. Medical therapy is the primary therapy for prolactinomas, and surgery by a skilled neurosurgeon is the first-line approach for other functioning pituitary adenomas. A multimodal treatment is frequently necessary to achieve biochemical and clinical control, especially, when surgery is not curative or when medical therapy fails. Several emerging, novel, medical treatments for acromegaly, Cushing's disease and prolactinomas are in phase II and III clinical trials and may become effective additions to the current drug armamentarium. The availability of various management options will allow an individualised treatment approach based on the unique tumour type, clinical situation and patient preference.

AIP and MEN1 mutations and AIP immunohistochemistry in pituitary adenomas in a tertiary referral center

BACKGROUND

Pituitary adenomas have a high disease burden due to tumor growth/invasion and disordered hormonal secretion. Germline mutations in genes such as MEN1 and AIP are associated with early onset of aggressive pituitary adenomas that can be resistant to medical therapy.

AIMS

We performed a retrospective screening study using published risk criteria to assess the frequency of AIP and MEN1 mutations in pituitary adenoma patients in a tertiary referral center.

METHODS

Pituitary adenoma patients with pediatric/adolescent onset, macroadenomas occurring ≤30 years of age, familial isolated pituitary adenoma (FIPA) kindreds and acromegaly or prolactinoma cases that were uncontrolled by medical therapy were studied genetically. We also assessed whether immunohistochemical staining for AIP (AIP-IHC) in somatotropinomas was associated with somatostatin analogs (SSA) response.

RESULTS

Fifty-five patients met the study criteria and underwent genetic screening for AIP/MEN1 mutations. No mutations were identified and large deletions/duplications were ruled out using MLPA. In a cohort of sporadic somatotropinomas, low AIP-IHC tumors were significantly larger (P = 0.002) and were more frequently sparsely granulated (P = 0.046) than high AIP-IHC tumors. No significant relationship between AIP-IHC and SSA responses was seen.

CONCLUSIONS

Germline mutations in AIP/MEN1 in pituitary adenoma patients are rare and the use of general risk criteria did not identify cases in a large tertiary-referral setting. In acromegaly, low AIP-IHC was related to larger tumor size and more frequent sparsely granulated subtype but no relationship with SSA responsiveness was seen. The genetics of pituitary adenomas remains largely unexplained and AIP screening criteria could be significantly refined to focus on large, aggressive tumors in young patients.

Insulin Resistance in Patients With Acromegaly

Acromegaly is characterized by chronic overproduction of growth hormone (GH) that leads to insulin resistance, glucose intolerance and, ultimately, diabetes. The GH-induced sustained stimulation of lipolysis plays a major role not only in the development of insulin resistance and prediabetes/diabetes, but also in the reduction of lipid accumulation, making acromegaly a unique case of severe insulin resistance in the presence of reduced body fat. In the present review, we elucidate the effects of GH hypersecretion on metabolic organs, describing the pathophysiology of impaired glucose tolerance in acromegaly, as well as the impact of acromegaly-specific therapies on glucose metabolism. In addition, we highlight the role of insulin resistance in the development of acromegaly-associated complications such as hypertension, cardiac disease, sleep apnea, polycystic ovaries, bone disease, and cancer. Taken together, insulin resistance is an important metabolic hallmark of acromegaly, which is strongly related to disease activity, the development of comorbidities, and might even impact the response to drugs used in the treatment of acromegaly.