Predictors and rates of treatment-resistant tumor growth in acromegaly

Medical treatment of acromegaly - When the tumor size matters: A narrative review

Medical treatment of acromegaly is generally positioned as a second line of treatment after pituitary adenoma surgery. With the rising availability and variety of medications for acromegaly increases our understanding of their effectiveness and safety. Volume of the published data on the impact of medical therapy on biochemical control of acromegaly, contrasts a relative lack of publications which comprehensively address pituitary tumor alterations under different drug modalities. Assessment of changes in GH-secreting adenoma volume is often overshadowed by clinicians' focus on GH and IGF-I levels during acromegaly treatment. Close analysis of studies published in the last two decades, reveals that both an increase and decrease in somatotropinoma volume are possible during treatment with any of available drugs for acromegaly. Changes in pituitary tumor size may arise from the biological nature of adenoma itself, independently of the administered medications. Therefore, an individual approach is necessary in the treatment of patients with acromegaly, based on repeated insight to their clinical, biochemical, pathological and imaging characteristics. In this review, we summarize and comment how pituitary tumor size is affected by the treatment with all currently available drugs in acromegaly: long-acting somatostatin receptor ligands of the first generation (octreotide LAR and lanreotide autogel) and the second generation (pasireotide-LAR), as well as pegvisomant (PEG) and cabergoline (CAB).

Recurrent acromegaly: a systematic review on therapeutic approaches

BACKGROUND AND OBJECTIVE

Management of recurrent acromegaly is challenging for both neurosurgeons and endocrinologists. Several treatment options including repeat surgery, medical therapy, and radiation are offered for such patients. The efficacy of these modalities for the treatment of recurrence has not been studied previously in the literature. In this study, we aim to systematically review the existing cases of recurrence and come to a conclusion regarding the appropriate treatment in such cases.

METHOD

A systematic review was performed through PubMed, Scopus, Web of Science, and Cochrane database to identify studies reporting the treatment outcome of recurrent acromegaly patients. Using PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, the included studies were reviewed for primary and secondary treatment, complications, and outcomes of the secondary treatment.

RESULTS

The systematic review retrieved 23 records with 95 cases of recurrent acromegaly. The mean time of recurrence was 4.16 years after the initial treatment. The most common primary treatment was surgery followed by radiotherapy. The remission rate was significantly higher in medical and radiotherapy compared to surgical treatment.

CONCLUSION

In cases of recurrent acromegaly, the patient may benefit more from radiotherapy and medical therapy compared to surgery. As the quality of evidence is low on this matter feature studies specifically designed for recurrent patients are needed.

Current and Future Advances in Surgical Therapy for Pituitary Adenoma

The vital physiological role of the pituitary gland, alongside its proximity to critical neurovascular structures, means that pituitary adenomas can cause significant morbidity or mortality. While enormous advancements have been made in the surgical care of pituitary adenomas, numerous challenges remain, such as treatment failure and recurrence. To meet these clinical challenges, there has been an enormous expansion of novel medical technologies (eg, endoscopy, advanced imaging, artificial intelligence). These innovations have the potential to benefit each step of the patient's journey, and ultimately, drive improved outcomes. Earlier and more accurate diagnosis addresses this in part. Analysis of novel patient data sets, such as automated facial analysis or natural language processing of medical records holds potential in achieving an earlier diagnosis. After diagnosis, treatment decision-making and planning will benefit from radiomics and multimodal machine learning models. Surgical safety and effectiveness will be transformed by smart simulation methods for trainees. Next-generation imaging techniques and augmented reality will enhance surgical planning and intraoperative navigation. Similarly, surgical abilities will be augmented by the future operative armamentarium, including advanced optical devices, smart instruments, and surgical robotics. Intraoperative support to surgical team members will benefit from a data science approach, utilizing machine learning analysis of operative videos to improve patient safety and orientate team members to a common workflow. Postoperatively, neural networks leveraging multimodal datasets will allow early detection of individuals at risk of complications and assist in the prediction of treatment failure, thus supporting patient-specific discharge and monitoring protocols. While these advancements in pituitary surgery hold promise to enhance the quality of care, clinicians must be the gatekeepers of the translation of such technologies, ensuring systematic assessment of risk and benefit prior to clinical implementation. In doing so, the synergy between these innovations can be leveraged to drive improved outcomes for patients of the future.

Prolactin and Growth Hormone Signaling and Interlink Focused on the Mammosomatotroph Paradigm: A Comprehensive Review of the Literature

Prolactin (PRL) and growth hormone (GH) are peptide hormones that bind to the class 1 cytokine receptor superfamily, a highly conserved cell surface class of receptors. Both hormones control their own secretion via a negative autocrine loop in their own mammosomatotroph, lactotroph or somatotroph. In this regard, GH and PRL are regulated by similar signaling pathways involving cell growth and hormone secretion. Thus, GH and PRL dysregulation and pituitary neuroendocrine tumor (PitNET) development may have common pathogenic pathways. Based on cell linage, lactotroph and somatotroph PitNETs come from pituitary-specific POU-class homeodomain transcription factor (Pit-1). Mammosomatotroph and plurihormonal PitNETs are a unique subtype of PitNETs that arise from a single-cell population of Pit-1 lineage. In contrast, mixed somatotroph-lactotroph PitNETs are composed of two distinct cell populations: somatotrophs and lactotrophs. Morphologic features that distinguish indolent PitNETs from locally aggressive ones are still unidentified, and no single prognostic parameter can predict tumor aggressiveness or treatment response. In this review, we aim to explore the latest research on lactotroph and somatotroph PitNETs, the molecular mechanisms involved in PRL and GH axis regulation and the signaling pathways involved in their aggressiveness, particularly focused on mammosomatotroph and mixed subtypes. Finally, we summarize epidemiological, clinical, and radiological features of these exceptional tumors. We aim to shed light, from basic to clinical settings, on new perspectives and scientific gaps in this field.

Giant growth hormone-secreting pituitary adenomas from the endocrinologist's perspective

OBJECTIVES

Since giant (≥40 mm) GH-secreting pituitary adenomas are rarely encountered, data on their characteristics and treatment outcomes are limited. We aimed to investigate the characteristics of giant GH-secreting pituitary adenomas and to compare their clinical, biochemical, imaging and histopathological features with non-giant macroadenomas.

MATERIALS AND METHODS

We have evaluated 15 (six female/nine male) and 57 (29 female/28 male) patients with acromegaly in giant and <40 mm adenoma groups, respectively. Patients with <40 mm adenoma were further divided into subgroups with adenoma size 20-29 mm and 30-39 mm.

RESULTS

In giant adenoma group, median (IQR) preoperative maximal diameter of adenoma was 40 mm (5 mm), median preoperative GH level was 40 (153.4) ng/mL and median baseline IGF-1 level was 2.19 (1.88) × ULN for age and sex. The number of surgeries was significantly higher in giant adenoma group (median 2, IQR 2) in which 66.7% of patients underwent repeated surgeries (p = 0.014). Residual tumor was detected after last operation in all patients with giant adenoma. Total number of treatment modalities administered postoperatively increased as adenoma size increased (p = 0.043). After a median follow-up duration of 10 years (IQR 10), hormonal remission was achieved in six patients (40%) of giant adenoma group, while the rate of hormonal remission in non-giant adenoma group was 37%. Although preoperative GH and IGF-1 levels and Ki-67 index tended to be higher with increasing adenoma size, there was no statistically significant difference between groups in terms of these variables, as well as age, sex and invasion status.

CONCLUSION

Hormonal remission rates of acromegaly patients with ≥20 mm pituitary macroadenoma were comparable. However, giant GH-secreting pituitary adenomas require an aggressive multimodal treatment approach.

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.

Predictors for Remission after Transsphenoidal Surgery in Acromegaly: A Dutch Multicenter Study

CONTEXT

Transsphenoidal surgery (TSS) is the primary treatment of choice in acromegaly. It is important to identify patients in whom surgical cure is not attainable at an early stage, both to inform patients on expected treatment outcome and to select those who are more likely to need additional therapy.

OBJECTIVE

To identify predictors for remission after TSS in acromegaly.

METHODS

Large multicenter study with retrospective data collection from 3 tertiary neurosurgical referral centers in The Netherlands. We analyzed clinical data since 2000 from 3 cohorts (Groningen, Nijmegen, and Rotterdam, total n = 282). Multivariate regression models were used to identify predictors of early biochemical remission (12 weeks to 1 year postoperatively) according to the 2010 consensus criteria, long-term remission (age- and sex-normalized insulin-like growth factor 1 [IGF-1] and the absence of postoperative treatment until last follow-up), and relative IGF-1 and growth hormone [GH] reduction.

RESULTS

A larger maximum tumor diameter (odds ratio [OR] 0.91, 95% CI 0.87-0.96, P ≤ .0001) was associated with a lower chance of early biochemical remission. A larger maximum tumor diameter (OR 0.93, 95% CI 0.89-0.97, P = .0022) and a higher random GH concentration at diagnosis (OR 0.98, 95% CI 0.96-0.99, P = .0053) were associated with a lower chance of long-term remission.

CONCLUSION

Maximum tumor diameter and random GH concentration at diagnosis are the best predictors for remission after TSS in acromegaly.

A single-center observational study assessing the predictive factors associated with the prognosis of acromegaly

AIM

The aim of this study was to clarify the prognostic values of various preoperative factors, including the surgeon's ability as well as the patient's age, gender, tumor size, cavernous sinus invasion, compression of the optic chiasm, hypopituitarism, immunohistochemical (IHC) staining pattern of the adenoma, and insulin-like growth factor-1 (IGF-1) level, in acromegalic patients who had undergone pituitary surgery.

STUDY DESIGN

This single-center, retrospective study assessed the medical records of 108 patients who had undergone pituitary surgery with the same neurosurgical team.

RESULTS

The mean total follow-up period after surgery was 44.8 (min: 24, max: 59) months. Remission was reported in 67 (62.0%) patients, and 57 (52.8%) patients did not experience recurrence. Initial tumor volume, IGF-1 level, and optic chiasm compression, but not patients' age, gender, cavernous sinus invasion, and IHC staining patterns of the adenoma, were prognostic of either remission or recurrence. An IGF-1 level of 860 ng/mLwas found to be a convenient cut-off point for determining remission.

CONCLUSIONS

The experience of the surgical team suggests that the initial tumor volume, IGF-1 level, and optic chiasm compression have high prognostic values in relation to pituitary surgery for patients with acromegaly.

[Early postoperative measurement of growth hormone level for prognosis of surgical outcomes in acromegaly]

AIM

To investigate the value of 24 hours post-surgery measurement of growth hormone (GH) level for prognosis of surgical outcomes in acromegaly.

MATERIALS AND METHODS

A prospective cohort study included 45 patients with newly diagnosed acromegaly. The degree of parasellar extension was measured on the preoperative sellar magnetic resonance imaging according to the Knosps classification. All patients underwent a transsphenoid adenomectomy performed by one neurosurgeon. Basal GH level was measured at 24 hours after surgery. The efficacy of transsphenoidal adenomectomy evaluated at 12 months after surgery.

RESULTS

Acromegaly remission was achieved in 19 (42%) of 45 patients at 12 months after surgery. Pituitary microadenomas and the absence of paracellular invasion, corresponding to Knosp Grade 02, had low prognostic value for long-term remission due to low sensitivity (31.6%) and low specificity (38.5%), respectively. The highest prognostic value for acromegaly remission was showed for 24 hours post-surgery GH level with cut-off 1.30 ng/ml with sensitivity of 96.2% (95% confidence interval 81.199.8%) and specificity of 84.2% (95% confidence interval 62.494.4%).

CONCLUSION

The study demonstrated the possibility of using GH level at 24 after surgery as a predictor for acromegaly remission. GH level 1.30 ng/ml at 24 hours after surgery showed better predictive value for long-term remission compared with the presence of microadenomas and Knosp Grade 02. The absence of decrease of GH level on the first day after surgery may serve as a reason for more close monitoring of patients in the postoperative period. Further studies in a larger number of observers are required to confirm our findings.

Effectiveness of Cabergoline Treatment in Patients with Acromegaly Uncontrolled with SSAs: Experience of a Single Tertiary Center

PURPOSE

To evaluate the effectiveness of cabergoline and the parameters affecting cabergoline response as add-on treatment to somatostatin analaogues (SSA) in patients with acromegaly uncontrolled with SSAs.

MATERIAL AND METHOD

One hundred and twenty-nine acromegalic patients uncontrolled with SSA who had cabergoline added to their treatment were included in this retrospective study. Patients were divided into the SSAs + cabergoline-responsive (group 1) and non-responsive groups (group 2), and biochemical, pathologic, and radiologic parameters were assessed.

RESULTS

IGF-1 normalization was achieved in 75 of 129 patients (58%) when cabergoline was added to the SSA treatment. Female patients were significantly higher in group 1 compared to group 2 (p=0.006). Group 1 had significantly smaller pre- and post-cabergoline tumor size (p=0.011, p=0.007 respectively), lower levels of IGF-1 in pre-and post-operative period (p=0.040, p=0.001), and lower levels of IGF-1 in pre- and post-cabergoline treatment (p<0.001). Cavernous invasion on sellar magnetic resonance imaging, dural invasion in pathologic examination were not significantly different between the groups. Sellar invasion in pathologic examination was significantly higher in group 1 (p=0.011). No significant difference was found in proliferation indices between two groups. The presence of fibrous bodies was significantly lower in group 1 (p=0.010).

CONCLUSION

Cabergoline can be added to the treatment of acromegalic patients uncontrolled with SSAs due to its ease of use and low economic cost, especially in patients with acromegaly who have small adenomas and no fibrous bodies.

Multivariable Prediction Model for Biochemical Response to First-Generation Somatostatin Receptor Ligands in Acromegaly

CONTEXT

First-generation somatostatin receptor ligands (fg-SRLs) represent the mainstay of medical therapy for acromegaly, but they provide biochemical control of disease in only a subset of patients. Various pretreatment biomarkers might affect biochemical response to fg-SRLs.

OBJECTIVE

To identify clinical predictors of the biochemical response to fg-SRLs monotherapy defined as biochemical response (insulin-like growth factor (IGF)-1 ≤ 1.3 × ULN (upper limit of normal)), partial response (>20% relative IGF-1 reduction without normalization), and nonresponse (≤20% relative IGF-1 reduction), and IGF-1 reduction.

DESIGN

Retrospective multicenter study.

SETTING

Eight participating European centers.

METHODS

We performed a meta-analysis of participant data from 2 cohorts (Rotterdam and Liège acromegaly survey, 622 out of 3520 patients). Multivariable regression models were used to identify predictors of biochemical response to fg-SRL monotherapy.

RESULTS

Lower IGF-1 concentration at baseline (odds ratio (OR) = 0.82, 95% confidence interval (CI) 0.72-0.95 IGF-1 ULN, P = .0073) and lower bodyweight (OR = 0.99, 95% CI 0.98-0.99 kg, P = .038) were associated with biochemical response. Higher IGF-1 concentration at baseline (OR = 1.40, (1.19-1.65) IGF-1 ULN, P ≤ .0001), the presence of type 2 diabetes (oral medication OR = 2.48, (1.43-4.29), P = .0013; insulin therapy OR = 2.65, (1.02-6.70), P = .045), and higher bodyweight (OR = 1.02, (1.01-1.04) kg, P = .0023) were associated with achieving partial response. Younger patients at diagnosis are more likely to achieve nonresponse (OR = 0.96, (0.94-0.99) year, P = .0070). Baseline IGF-1 and growth hormone concentration at diagnosis were associated with absolute IGF-1 reduction (β = 0.90, standard error (SE) = 0.02, P ≤ .0001 and β  = 0.002, SE = 0.001, P = .014, respectively).

CONCLUSION

Baseline IGF-1 concentration was the best predictor of biochemical response to fg-SRL, followed by bodyweight, while younger patients were more likely to achieve nonresponse.

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.

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.

Clinical assessment of patients with acromegaly

Background:

In this study, we aimed to retrospectively evaluate treatment outcomes and treatment methods in acromegaly patients.

Materials and Methods:

The study included 65 acromegaly patients followed in Sakarya University Faculty of Medicine Department of Endocrinology in Turkey between 2004 and 2013. Clinical, biochemical, and radiological data were obtained retrospectively from the medical files of the patients. All cases have been discussed in the endocrinology and pituitary surgery council, and a multidisciplinary treatment approach had been chosen in management.

Results:

Sixty-five patients were included in the study. Of the patients, 57% were female. Mean age was 45.3 ± 9.2 years old. Of the cases, 12.3% were microadenomas (n = 8, tumor diameter <10 mm) and 87.6% were macroadenomas (n = 57, tumor diameter ≥10 mm). In our study, 70% remission was achieved with the first operation and medical treatment. Patients with invasive acromegaly without remission after the first operation underwent reoperation, medical treatment, and conventional or stereotactic radiotherapy and achieved 45% remission rate.

Conclusion:

Pituitary surgery is the first treatment option for acromegaly. In patients who could not be remissioned after the first operation, remission can be achieved by combined therapy consist of reoperation, medical treatment, and conventional or stereotactic radiotherapy.

European Society of Endocrinology Clinical Practice Guidelines for the management of aggressive pituitary tumours and carcinomas

BACKGROUND

Pituitary tumours are common and easily treated by surgery or medical treatment in most cases. However, a small subset of pituitary tumours does not respond to standard medical treatment and presents with multiple local recurrences (aggressive pituitary tumours) and in rare occasion with metastases (pituitary carcinoma). The present European Society of Endocrinology (ESE) guideline aims to provide clinical guidance on diagnosis, treatment and follow-up in aggressive pituitary tumours and carcinomas.

METHODS

We decided upfront, while acknowledging that literature on aggressive pituitary tumours and carcinomas is scarce, to systematically review the literature according to the GRADE (Grading of Recommendations Assessment, Development and Evaluation) system. The review focused primarily on first- and second-line treatment in aggressive pituitary tumours and carcinomas. We included 14 single-arm cohort studies (total number of patients = 116) most on temozolomide treatment (n = 11 studies, total number of patients = 106). A positive treatment effect was seen in 47% (95% CI: 36-58%) of temozolomide treated. Data from the recently performed ESE survey on aggressive pituitary tumours and carcinomas (165 patients) were also used as backbone for the guideline. SELECTED RECOMMENDATION: (i) Patients with aggressive pituitary tumours should be managed by a multidisciplinary expert team. (ii) Histopathological analyses including pituitary hormones and proliferative markers are needed for correct tumour classification. (iii) Temozolomide monotherapy is the first-line chemotherapy for aggressive pituitary tumours and pituitary carcinomas after failure of standard therapies; treatment evaluation after 3 cycles allows identification of responder and non-responder patients. (iv) In patients responding to first-line temozolomide, we suggest continuing treatment for at least 6 months in total. Furthermore, the guideline offers recommendations for patients who recurred after temozolomide treatment, for those who did not respond to temozolomide and for patients with systemic metastasis.

Pegvisomant in acromegaly: an update

BACKGROUND

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

AIM

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

RESULTS

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

CONCLUSIONS

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

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.

Somatostatin receptor ligands in acromegaly: clinical response and factors predicting resistance

INTRODUCTION

Somatostatin (SST) receptor ligands (SRL), in particular those of first generation (Octreotide and Lanreotide), are widely used in medical treatment of acromegaly, but they assure biochemical control of disease (and the possibility of an improvement of clinical symptoms and tumor shrinkage), only in a subset of patients.

DISCUSSION

The mechanisms underlying the so called "SRL resistance" are various and involve in particular SST receptor expression and molecular pathways of signal transduction. Different predictors of SRL response have been reported, including clinical and biochemical features (gender, age, growth hormone and insulin-like growth factor-I levels at diagnosis), and tumor characteristic (both at preoperative magnetic resonance imaging study and histopathology) as well as expression of SST receptors. In some cases, only a "partial resistance" to SST can be detected, probably due to the presence of other impaired molecular mechanisms involved in signal transduction, which compromise specific pathways and not others. This may explain some cases of dissociated response between biochemical control and tumor shrinkage.

Safety of long-term treatment with Pegvisomant: analysis of Spanish patients included in global ACROSTUDY

PURPOSE

To evaluate the long-term safety of Pegvisomant (PEG) in the Spanish cohort of ACROSTUDY.

METHODS

As of July 2013, 199 Spanish patients were included in ACROSTUDY, a global non interventional safety PEG surveillance study. Patients were observed for safety, biochemical outcome and magnetic resonance imaging evaluations.

RESULTS

PEG was administered during an average period of 6.7 ± 2.1 years and a mean daily dose of 15.5 ± 7.5 mg. 48.2% of patients received PEG monotherapy. 90.9% of patients had received other medical treatment before PEG start. 195 adverse events (AEs) were reported in 88 patients (44.2%), and serious AEs were described in 31 patients (15.6%). There were no cases of liver tests >10 ULN, or permanent liver damage. Tumor size changes were locally reported in 61 cases (33.5%), with increases observed in 11 patients (6%). In acromegalic patients with diabetes mellitus a decrease in fasting serum glucose value was reported, reaching statistical significance after 1 and 4 years of treatment (-24.6 and -25.9 mg/dl, p = 0.04). After 60 months, normal or lower limit of normal (LLN) IGF-I levels were found in 67.9% of patients. 85.5% of patients showed an IGF-I normal or <LLN at any time after PEG start. Most patients with uncontrolled IGF-I levels were on submaximal PEG doses.

CONCLUSIONS

ACROSTUDY carried out with the Spanish cohort confirmed that PEG has a favorable safety and efficacy profile. The percentage of patients considered under control was similar to data reported globally and in other local ACROSTUDY results.

Growth hormone tumor histological subtypes predict response to surgical and medical therapy

Growth hormone (GH) pituitary tumors are associated with significant morbidity and mortality. Current treatments, including surgery and medical therapy with somatostatin analogs (SSA), dopamine agonists and/or a GH receptor antagonist, result in disease remission in approximately half of patients. Predictors of GH tumor response to different therapies have been incompletely defined based on histologic subtype, particularly densely (DG) versus sparsely (SG) granulated adenomas. The aim of this study was to examine our own institutional experience with GH adenomas and correlate how subtype related to clinical parameters as well as response to surgery and medical therapies. A retrospective chart review of 101 acromegalic patients operated by a single neurosurgeon was performed. Clinical data were correlated with histologic subtype and disease control, as defined by IGF-1 levels, and random growth hormone levels in response to surgery and/or medical therapies. SG tumors, compared to DG, occurred in younger patients (p = 0.0010), were 3-fold larger (p = 0.0030) but showed no differences in tumor-invasion characteristics (p = 0.12). DG tumors had a higher rate of remission in response to surgery compared to SG, 65.7 vs. 14.3 % (p < 0.0001), as well as to medical therapy with SSAs (68.8 % for DG vs. 28.6 % for SG tumors; p = 0.028). SG tumors not controlled with SSAs consistently responded to a switch to, or addition of, a GH receptor antagonist. Histological GH tumor subtyping implicates a different clinical phenotype and biologic behavior, and provides prognostic significance for surgical success and response to medical therapies.

Escape and lipodystrophy in acromegaly during pegvisomant therapy, a retrospective multicentre Spanish study

BACKGROUND

Pegvisomant is an effective treatment for acromegaly.

OBJECTIVE

To investigate escape (loss of biochemical control in patients previously controlled) and lipodystrophy in acromegalic patients treated with pegvisomant and to evaluate possible associations with clinical features.

PATIENTS AND METHODS

Multicentre retrospective study involving 19 Spanish centres.

RESULTS

Ninety-seven patients were included (59% women, mean age at diagnosis 42 ± 13 years, 80% macroadenomas); mean follow-up on pegvisomant was 5 ± 2·5 years, and 89 (92%) achieved normal IGF-1. Escape was reported in 30/89 (34%) of responders, after a mean treatment duration of 25 ± 21 months. The mean initial dose of pegvisomant was 11 ± 5 mg/day, and mean dose at escape was 14 ± 7 mg/day. Most patients (26/30, 87%) achieved control with dose increase (57%), additional medical treatment (3%) or both (27%). Mean new dose that controlled IGF-1 after escape was 20 ± 7 mg/day. Treatments associated were somatostatin analogues (SSA in 47%), cabergoline (CAB in 47%) and both (6%). Lipodystrophy was observed in 15 patients (13 females), mild in six, moderate in six, severe in three and persistent in four. Among patients with lipodystrophy, three escaped and three were nonresponders to pegvisomant. Four patients discontinued the drug, and four had dose reductions because of lipodystrophy. It tended to be more frequent in females (P = 0·06) and in patients treated with triple association SSA+CAB+PEG (P = 0·018). No relationship between escape and clinical variables was found, except prior CAB (P = 0·04) and metformin treatment (0·02) and grade of lipodystrophy (P = 0·02).

CONCLUSIONS

A significant proportion of patients treated with pegvisomant escaped (34%); however, the majority (87%) was easily controlled with either dose increase, further medical treatment or both. Lipodystrophy developed in 15%, mostly females, and influenced the response to treatment.

Aggressive tumors and difficult choices in acromegaly

PURPOSE

The current article looks at some of the factors associated with pituitary adenomas displaying unusually aggressive biological and clinical behaviour in patients with acromegaly.

METHODS

This was a retrospective, narrative review of previously published evidence chosen at the authors' discretion and presented from the perspective of a Latin American case study.

FINDINGS AND CONCLUSIONS

Although most pituitary tumors in acromegalic patients are benign and non-aggressive many can behave more aggressively, compromising local surrounding structures. These lesions tend to respond poorly to somatostatin analogs, have a higher risk of recurrence after surgery and, thus, a worse prognosis. Patients with more aggressive tumors constitute a particular challenge, as they often require several therapeutic approaches and may be difficult to manage, especially when options are restricted due to limited resources.

Management of endocrine disease: GH excess: diagnosis and medical therapy

Acromegaly is predominantly caused by a pituitary adenoma, which secretes an excess of GH resulting in increased IGF1 levels. Most of the GH assays used currently measure only the levels of the 22 kDa form of GH. In theory, the diagnostic sensitivity may be lower compared with the previous assays, which have used polyclonal antibodies. Many GH-secreting adenomas are plurihormonal and may co-secrete prolactin, TSH and α-subunit. Hyperprolactinaemia is found in 30-40% of patients with acromegaly, and hyperprolactinaemia may occasionally be diagnosed before acromegaly is apparent. Although trans-sphenoidal surgery of a GH-secreting adenoma remains the first treatment at most centres, the role of somatostatin analogues, octreotide long-acting repeatable and lanreotide Autogel as primary therapy is still the subject of some debate. Although the normalisation of GH and IGF1 levels is the main objective in all patients with acromegaly, GH and IGF1 levels may be discordant, especially during somatostatin analogue therapy. This discordance usually takes the form of high GH levels and an IGF1 level towards the upper limit of the normal range. Pasireotide, a new somatostatin analogue, may be more efficacious in some patients, but the drug has not yet been registered for acromegaly. Papers published on pasireotide have reported an increased risk of diabetes mellitus due to a reduction in insulin levels. Pegvisomant, the GH receptor antagonist, is indicated - alone or in combination with a somatostatin analogue - in most patients who fail to enter remission on a somatostatin analogue. Dopamine-D2-agonists may be effective as monotherapy in a few patients, but it may prove necessary to apply combination therapy involving a somatostatin analogue and/or pegvisomant.

Emerging drugs for acromegaly

INTRODUCTION

Acromegaly is a rare disease that severely impacts patients' health all the while, being a slowly progressing illness. In the past decades, advancements in treatment modalities, especially development of new drugs, as well as focused guidelines has improved management of acromegaly. Still, many patients are considered not sufficiently treated and there remains an ongoing need for further development.

AREAS COVERED

This article reviews new medical treatments currently under clinical investigation (such as pasireotide, oral octreotide and somatoprim) and under experimental development (such as octreotide implants, CAM2029 and ATL-1103).

EXPERT OPINION

As it seems unlikely that one single agent may achieve cure in 100% of cases, there is an urgent need for new agents that help patients where current medication fails. Imperatively, this means we have to improve our understanding of the underlying pathogenetic and molecular mechanisms.

Predictors of endoscopic transsphenoidal surgery outcome in acromegaly: patient and tumor characteristics evaluated by magnetic resonance imaging

The availability of various first-line treatment modalities for acromegaly and evolving surgical techniques emphasize the need for accurately defined predictors of surgical outcome. We retrospectively analysed the outcome of 30 patients with acromegaly after initial endoscopic transsphenoidal surgery in two university hospitals from 2001 until 2009, and reviewed comparable literature investigating predictive tumor characteristics. Medical records were monitored for patient characteristics. Each pituitary magnetic resonance imaging (MRI) scan was revised independently by two neuroradiologists using a standardised analysis form to record distinctive predefined tumor characteristics. All characteristics were independently analysed as predictors for persistent disease, and a multivariable predictive model was created. Literature from 2000 onwards was searched for studies describing tumor characteristics predictive for surgical outcome. The cohort consisted of 27 macroadenomas with 90 % demonstrating signs of parasellar extension. The surgical cure rate overall was 30 %. Independently, next to male sex and increasing tumor size, infrasellar and parasellar extension based on MRI staging tended to increase the risk of persistent disease. In a multivariable analysis, sex and parasellar extension of the tumor were demonstrated to be the variables allowing for the best fitted predictive model for persistent disease. Earlier studies on preoperative tumor characteristics showed comparable results, although these were based on several different tumor classification systems. This retrospective study demonstrates that accurately defined tumor characteristics based on imaging, especially for cavernous sinus invasion, can be helpful in predicting surgical outcome. Comparative studies on different treatment modalities are essential for clinical practice within the scope of re-evaluation of the role of surgery in GH-secreting adenomas.

Management options for persistent postoperative acromegaly

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

Results of gamma knife radiosurgery in acromegaly

Objective. Single-session radiosurgery with Gamma Knife (GK) may be a potential adjuvant treatment in acromegaly. We analyzed the safety and efficacy of GK in patients who had previously received maximal surgical debulking at our hospital. Methods. The study was a retrospective analysis of hormonal, radiological, and ophthalmologic data collected in a predefined protocol from 1994 to 2009. The mean age at treatment was 42.3 years (range 22-67 yy). 103 acromegalic patients participated in the study. The median follow-up was 71 months (IQ range 43-107). All patients were treated with GK for residual or recurrent GH-secreting adenoma. Results. Sixty-three patients (61.2%) reached the main outcome of the study. The rate of remission was 58.3% at 5 years (95% CI 47.6-69.0%). Other 15 patients (14.6%) were in remission after GK while on treatment with somatostatin analogues. No serious side effects occurred after GK. Eight patients (7.8%) experienced a new deficit of pituitary function. New cases of hypogonadism, hypothyroidism, and hypoadrenalism occurred in 4 of 77 patients (5.2%), 3 of 95 patients (3.2%), and 6 of 100 patients at risk (6.0%), respectively. Conclusion. In a highly selected group of acromegalic patients, GK treatment had good efficacy and safety.

MGMT immunoexpression in growth hormone-secreting pituitary adenomas and its correlation with Ki-67 labeling index and cytokeratin distribution pattern

Recent publications suggest the utility of temozolomide (TMZ) in the management of aggressive pituitary adenomas and carcinomas, resistant to conventional treatments. The response to TMZ is inversely correlated with tumoral expression of O-6 methylguanine DNA methyl transferase (MGMT). Therefore, we aimed to assess MGMT immunoexpression in pure GH-secreting pituitary adenomas, in an effort to predict the likelihood of response to TMZ, and to correlate MGMT immunoexpression with Ki-67 LI and cytokeratin (CK) distribution pattern. Our material consisted of 36 GH-secreting pituitary adenomas (21 female,15 male, mean age 42.5±10.5), operated at our center between 2003 and 2010. Immunostaining for MGMT, Ki-67, and CK was performed using avidin-biotin-peroxidase complex method. Immunoreactivity for MGMT and Ki-67 was evaluated microscopically and recorded as percentages of positive nuclear immunostaining. CK distribution pattern was also evaluated microscopically and assoreted into dot-like and nondot-like pattern subtypes. MGMT immunoexpression scored as 0=none, 1=<10%, 2=<25%, 3=<50%, and 4=>50%. Staining for MGMT was <10% (score 1) in 30 (83.3%), 10-25% (score 2) in 3 (8.3%), 25-50% (score 3) in 2 (5.6%) and >50% (score 4) in 1 (2.8%) of the tumors, respectively. There was no correlation between Ki-67 LI and CK distribution pattern with MGMT immunoreactivity (P>0.05). Data from the current study suggest a large proportion of GH-secreting adenomas, including those with dot-like CK distribution pattern and high Ki-67 LI, demonstrate negative/low MGMT immunoreactivity and could be treated with TMZ, if conventional treatment fails.

Rosiglitazone as an option for patients with acromegaly: a case series

INTRODUCTION

In the patient with acromegaly, pituitary surgery is the therapeutic standard. Despite undergoing surgery, a significant number of patients with acromegaly continue to have uncontrolled growth hormone secretion. These patients require other treatments such as external irradiation and/or drug therapy.

CASE PRESENTATION

We present the clinical and laboratory responses to six months of treatment with rosiglitazone in four cases. In all four cases, the patients had persistent growth hormone overproduction despite previous surgical treatment and other conventional therapy. Case 1 is a 57-year-old Caucasian woman, case 2 is a 51-year-old Hispanic man, case 3 is a 32-year-old Hispanic woman, and case 4 is a 36-year-old Hispanic man. In three of these patients, basal and nadir growth hormone and insulin-like growth factor 1 levels were significantly decreased (P < 0.05 and P < 0.01, respectively).

CONCLUSION

Rosiglitazone could be a treatment option in select patients with acromegaly.

Resistance to somatostatin analogs in acromegaly

Somatostatin analogs (SA) are widely used in acromegaly, either as first-line or adjuvant treatment after surgery. First-line treatment with these drugs is generally used in the patients with macroadenomas or in those with clinical conditions so severe as to prevent unsafe reactions during anesthesia. Generally, the response to SA takes into account both control of GH and IGF-I excess, with consequent improvement of clinical symptoms directly related to GH and IGF-I excess, and tumor shrinkage. This latter effect is more prominent in the patients treated first-line and bearing large macroadenomas, but it is also observed in patients with microadenomas, even with little clinical implication. Predictors of response are patients' gender, age, initial GH and IGF-I levels, and tumor mass, as well as adequate expression of somatostatin receptor types 2 and 5, those with the highest affinity for octreotide and lanreotide. Only sporadic cases of somatostatin receptor gene mutation or impaired signaling pathways have been described in GH-secreting tumors so far. The response to SA also depends on treatment duration and dosage of the drug used, so that a definition of resistance based on short-term treatments using low doses of long-acting SA is limited. Current data suggest that response to these drugs is better analyzed taking together biochemical and tumoral effects because only the absence of both responses might be considered as a poor response or resistance. This latter evidence seems to occur in 25% of treated patients after 12 months of currently available long-acting SA.

Tumor volume of growth hormone-secreting pituitary adenomas during treatment with pegvisomant: a prospective multicenter study

CONTEXT

Clinical and biochemical remission in acromegaly can frequently be achieved with the recombinant GH receptor antagonist pegvisomant, even when other treatments fail. However, increases in tumor volume have been reported.

OBJECTIVE

Because previous studies suffer from inhomogenous magnetic resonance imaging (MRI) protocols, this prospective study examined the long-term course of adenoma volume during pegvisomant therapy by standardized MRI.

DESIGN

Five centers in Germany participated. High-resolution MRI was performed at baseline and 6, 12, and 24 months after enrollment.

SETTING/PATIENTS

Patients were outpatients, and pegvisomant is third-line therapy in most of the cases.

MAIN OUTCOME MEASURES

The primary end point was tumor volume at 24 month follow-up, measured by a single, double-blinded rater.

RESULTS

Forty-five of 61 patients completed 24 months' follow-up (73.8%). Tumor volume increase greater than 25% during the study was observed in three of 61 patients (4.9%), all during the first year of enrollment. All three patients had had octreotide treatment before initiation of pegvisomant; none of them had had radiotherapy. All volumetric findings were comparable with clinical radiological interpretations. ANOVA revealed no significant change in tumor volume after 24 months (n = 45).

CONCLUSIONS

This study shows that pegvisomant therapy infrequently coincides with tumor growth during long-term treatment of acromegaly. Because all significant tumor volume increases occurred during the first year, these changes might correlate to the change of medication and thus be the result of a rebound from somatostatin-induced shrinkage.

The German ACROSTUDY: past and present

Pivotal studies have demonstrated that pharmacotherapy with pegvisomant (Somavert) is a highly effective treatment for acromegaly. Since clinical experience with the drug was very limited, the Pegvisomant Observational Study was launched in Germany immediately with the drug becoming commercially available to patients early in 2004. Its purpose was to record safety and efficacy data on as many patients as possible. As of 12th August 2008 a total of 371 patients (185 males, 186 females) had been included in the study. They were on pegvisomant therapy for an average of 118 weeks. Median and mean doses of pegvisomant were 15 and 16.4 mg/day respectively. Treatment efficacy was monitored by IGF1 levels and the patients symptoms were evaluated by completion of a questionnaire (patient-assessed acromegaly symptom questionnaire). Safety data included liver function tests, fasting glucose, HbA1c measurements, and tumor size monitoring by repeated magnetic resonance imaging. Normalization of IGF1 ranged from 55.7% of the 273 patients assessed after 6 months to 71.3% of 202 patients assessed after 24 months of treatment. It was 70.7% after 36 months (133 patients), 64.8% at 48 months (71 patients), and 58.4% after 60 months (24 patients). In 39 patients (10.9%) treatment was discontinued due to serious adverse events or adverse events with 25 (6.7%) of these patients having a potential causal relationship with the pegvisomant treatment. Liver function tests became abnormal in 20 patients and another three patients were recorded to have hepatobiliary disorders. Tumor size increase was reported in 20 patients, but only confirmed in nine patients by careful revision of all available images. Local injection site reactions were observed in 12 patients. In conclusion, in this large group of pegvisomant-treated patients, long-term data for up to 5 years of treatment are now available. In 71.3% of patients with previously not sufficiently treatable acromegaly, IGF1 levels were normalized by pegvisomant therapy. Elevated transaminases usually normalized after discontinuation but in half of the affected patients also despite continuation of treatment without dose alteration. Tumor progression was a rare event. It did not exceed the expected rate in patients with acromegaly not treated with pegvisomant. As from this presently largest database of acromegalic patients treated with pegvisomant, long-term results are encouraging. The German data are now merged into the global ACROSTUDY and will constitute a major portion of the international ACROSTUDY project as a continuing global web-based observational study.

Tumor ZAC1 expression is associated with the response to somatostatin analog therapy in patients with acromegaly

Somatostatin analogs (SSA) with their potent antisecretory and antiproliferative effects are the main medical treatment option for patients with neuroendocrine tumors, such as gastroenteropancreatic and acromegaly-associated growth hormone secreting pituitary tumors. Although a good portion of acromegalic patients gets normalized after SSA treatment, strict hormonal control is not achieved in a sizeable proportion of these patients. The reasons for this incomplete response to SSA treatment are unclear. We have found that the tumor suppressor ZAC1 (LOT1/PLAGL1) is essential for the antiproliferative effect of SSA in pituitary tumor cells. The aim of the present retrospective cohort study was to determine whether ZAC1 immunoreactivity in archival somatotrophinoma tissue derived from 45 patients with acromegaly routinely pretreated with SSA before surgery, was associated with response to SSA (normalization of GH, IGF-I and presence of tumor shrinkage). All tumors displayed ZAC1 immunoreactivity [weak (+; n = 15), moderate (++; n = 16) and strong (+++; n = 14)]. A significant positive correlation was found between strong ZAC1 immunoreactivity and IGF-I normalization and presence of tumor shrinkage after SSA treatment, which was not affected by age at diagnosis, gender or duration of SSA treatment. These in vivo data combined with the antiproliferative properties of ZAC1/Zac1 provide evidence of a mechanistic role for this transcription factor on SSA induced tumor shrinkage and hormone normalization.

Significant tumour shrinkage after 12 months of lanreotide Autogel-120 mg treatment given first-line in acromegaly

OBJECTIVE

To evaluate GH and IGF-I control and tumour shrinkage in newly diagnosed patients with acromegaly treated first-line with lanreotide-Autogel (ATG) 120 mg. Design Open, prospective.

PATIENTS

Twenty-six patients (17 women, aged 31-70 years): eight enclosed and 12 extrasellar (eight invasive) macroadenomas and six microadenomas (one invasive). ATG 120 mg initially given every 4 weeks for 12 weeks; then intervals between injections increased to every 6 or 8 weeks if GH levels were <or= 2.5 or < 1 microg/l (equal to 6.5 and 2.6 mU/l), respectively.

RESULTS

Final dosage was ATG 120 mg every 4 weeks in nine patients (34.6%), every 6 weeks in eight patients (30.8%) and every 8 weeks in the remaining nine patients (34.6%). After 12 months, both GH and IGF-I were controlled in 14 patients (53.8%). The mean tumour volume decreased from 1405 +/- 1827 mm(3) at study entry to 960 +/- 1381 mm(3) after 6 months, and 799 +/- 1161 mm(3) after 12 months (P < 0.0001). Overall tumour shrinkage was 35.8 +/- 28.1% after 6 months and 48.4 +/- 27.6% after 12 months. After 12 months, 20 patients (76.9%) achieved > 25% tumour shrinkage: 12 of 14 with controlled disease (85.7%) and 8 of 12 with noncontrolled disease (66.7%; P = 0.49). Hyperhydrosis, paresthesiae and arthralgias significantly reduced after treatment. No patient withdrew from the study because of adverse events.

CONCLUSION

ATG 120 mg in newly diagnosed patients with acromegaly controls GH and IGF-I secretion in 53.8% and induces >or= 25% tumour shrinkage in 76.9% during a 12-month period. The treatment was associated with improvement of clinical symptoms and with a good safety profile.

Medical therapy of pituitary adenomas: effects on tumor shrinkage

The efficacy of dopamine-agonists (DA) in patients with prolactinomas and that of somatostatin analogues (SSA) in those with GH- and TSH-secreting adenomas is well established. More recently, data are accumulating suggesting a potential therapeutic role of DA also in patients with ACTH-secreting and clinically non-functioning (NFA) pituitary adenomas. This review aims at summarizing published results of DA and SSA on tumor shrinkage in patients with different histotypes of pituitary adenomas. Results of tumor shrinkage are of clinical relevance as tumor size is the one of the most important determinant of surgical outcome. While reduction of tumor size more than 50% of baseline size in macroprolactinomas treated with DA is a frequent finding in patients with GH-secreting adenomas treated with SSA tumor shrinkage only recently is becoming frequent thanks to the availability of depot formulations. Data on tumor shrinkage in patients with TSH-secreting adenomas treated with SSA are limited because of the rarity of these tumors. Very recently, DA have been reported of some efficacy also in patients with ACTH-secreting adenomas but data are still very limited. NFA respond very scantly to both DA and SSA even if receptors targeting these drugs are present. Whether this is due to limited receptor number or alterations of post-receptor pathway is still unknown.

Medical therapy in patients with acromegaly: predictors of response and comparison of efficacy of dopamine agonists and somatostatin analogues

CONTEXT

Acromegaly is associated with increased morbidity and mortality. Treatment options include surgery, radiotherapy, and medical therapy.

AIMS

The objective of the study was to examine the role of prolactin status, prior surgery, and radiotherapy on the response to medical therapy in patients with acromegaly and assess the relative efficacy of dopamine agonist therapy compared with somatostatin analog therapy.

MATERIALS AND METHODS

A total of 276 patients with acromegaly received either dopamine agonists (DA) and/or somatostatin analogs (SSA). One hundred seventy-two patients had received surgery and 73 radiotherapy prior to receiving medical therapy. One hundred ninety-eight of 276 received DA, and 143 of 276 received SSA. GH and IGF-I values at baseline and after 12 months on therapy were analyzed.

RESULTS

In the DA group, basal prolactin concentration did not predict response to therapy, GH percent reduction: hyperprolactinemia, 26.7% (-10.4 to 48) vs. normoprolactinemia, 34.8% (0.2-53.2), P = 0.58; IGF-I percent reduction: hyperprolactinemia 30.0% (9.2-43.1) vs. normoprolactinemia 16.8% (4-37), P = 0.45. Prior surgery was not associated with any difference in response to DA: GH percent reduction (P = 0.1) and IGF-I percent reduction (P = 0.08). By contrast, prior radiotherapy was associated with an enhanced efficacy of GH response to DA, P = 0.02. In the SSA group, there was no effect of prior surgery or radiotherapy on response of GH, but radiotherapy was associated with less marked IGF-I percent reduction (P = 0.05). SSA were more potent than DA at decreasing both GH [62.8% (20.7-85%) vs. 42.4% (-6.5 to 68.6), P < 0.008] and IGF-I [SSA 40.4% (0-64.3) vs. 8% (0-40.8), P = 0.05].

CONCLUSIONS

The effects of DA are irrespective of baseline prolactin concentrations. Prior radiotherapy is associated with differences in GH and IGF-I response to DA and SSA therapy.

The role of stereotactic radiotherapy in patients with growth hormone-secreting pituitary adenoma

CONTEXT

Single-session stereotactic radiotherapy (SR) may be a potential adjuvant treatment in acromegaly.

OBJECTIVE

We analyzed the safety and efficacy of SR in patients who had previously received maximal surgical debulking at our center.

DESIGN

The study was a retrospective analysis of hormonal, radiological, and ophthalmologic data collected in a predefined protocol from 1994 through 2006.

SETTING

The study was performed at a university hospital.

PATIENTS

Eighty-three acromegalic patients, 52 women and 31 men, with a mean age of 42.6 +/- 1.2 yr, participated in the study. The median follow-up was 69 months (interquartile range 44-107 months).

INTERVENTION

The patients were treated with SR for residual or recurrent GH-secreting adenoma.

MAIN OUTCOME MEASURE

Normalization of age- and sex-adjusted IGF-I levels together with a basal GH level below 2.5 microg/liter without concomitant GH-suppressive drugs was the goal of therapy.

RESULTS

Fifty patients (60.2%) reached the main outcome of the study. The rate of remission was 52.6% at 5 yr [95% confidence interval (CI) 40.6-64.6%]. Another 13 patients (15.7%), who were resistant to somatostatin analogs, were in remission after SR. Multivariate analysis showed that low basal GH and IGF-I levels were associated with a favorable outcome. No serious side effects occurred after SR. The 5-yr cumulative risk of new onset hypogonadism, hypothyroidism, or hypoadrenalism was 3.6% (95% CI 0-8.6%), 3.3% (95% CI 0-7.7%), and 4.9% (95% CI 0-10.4%), respectively.

CONCLUSION

In a highly selected group of acromegalic patients, SR treatment had good efficacy and safety. This may lead to reconsider the role of SR in the therapeutic algorithm of acromegaly.

Cost of management of invasive growth hormone-secreting macroadenoma

BACKGROUND

At the time of diagnosis, macroadenomas represent 60-80% of GH secreting adenomas, of which 25-30% are invasive macroadenomas. These aggressive tumors have the worst surgical success rates in terms of cure, and often need several therapeutic approaches in order to control disease status. Acromegalic patients are subject to increased mortality and important health resource consumption related to their associated co-morbidities, in addition to the costs that are related to diagnosis itself and initial treatment of the disease.

OBJECTIVE

Assessment of the cost of initial management and outcome of acromegalic patients with invasive pituitary adenomas.

STUDY DESIGN

Retrospective and observational study of review of records.

SETTING

Two tertiary hospitals.

PATIENTS

11 consecutive patients between 18 and 80 yr old diagnosed with acromegaly due to an invasive pituitary macroadenoma.

INTERVENTION

Collection of data of biochemical and radiological tests, specialist visits, hospitalisation, surgery, pharmacological and radiotherapy treatment at diagnosis and over 4 yr of follow-up after initial treatment. Costs were evaluated using the data of the Centre for Health Economics and Social Policy Studies and the Official College of Pharmacists of Spain.

MAIN OUTCOME MEASURE

Global and patient/yr follow-up costs of illness.

RESULTS

The mean costs for acromegaly for the period of follow-up ranged from 7,072 to 9,874 euro/patient/yr, for biochemically non-controlled (no.=6) and controlled patients (no.=5) respectively. The most important cost in the perioperative period was for admission in the intensive care unit. After surgery, SS analogues were the principal contributors to the economic burden.

CONCLUSION

In this paper we have for the first time presented a pharmacoeconomic study of GH secreting invasive macroadenoma. The poor prognosis of our cohort of patients and the higher rate of controlled patients and normal IGF-I levels warrant the employment of multiple therapeutic options. The cost associated with this treatment in this complex disease of low prevalence is not excessive and can be supported by healthcare services.

The role of lanreotide Autogel® in the treatment of acromegaly

Acromegaly is a rare disease, but all clinicians have to be aware of the diagnosis in order to minimize the negative consequences of increased levels of growth hormone and IGF-I, and the possible impact of a pituitary macroadenoma. Surgery remains the first-line therapy and may alleviate both hormonal excess and symptoms due to tumor mass effects. Postoperatively, however, many patients may need adjunctive therapy. Somatostatin analogs were marketed for clinical use in the 1980s. The depot formulations of the synthetic somatostatin analogs octreotide and lanreotide, octreotide acetate long-acting repeatable and lanreotide sustained release, were developed by incorporating the analogs into microspheres. The advantage of the new formulation of lanreotide, lanreotide Autogel^®, is the prefilled syringe of lanreotide and water. The choice of analog should be individualized for each patient based on level of efficacy, adverse event profile and preferred mode of administration. Approximately a third of acromegalic patients are resistant to the currently available somatostatin analogs. Monotherapy using cabergoline or pegvisomant is clinically available. Adding cabergoline to a somatostatin analog may be advantageous in selected patients and promising data exist regarding combination therapy with pegvisomant. Radiotherapy is still an option; however, although treating comorbidities and avoiding hypopituitarism is very important, radiotherapy should only be used for selected patients where treatment targets cannot be achieved by using the other therapies.

Molecular diagnosis of pituitary adenoma predisposition caused by aryl hydrocarbon receptor-interacting protein gene mutations

Pituitary adenomas are common neoplasms of the anterior pituitary gland. Germ-line mutations in the aryl hydrocarbon receptor-interacting protein (AIP) gene cause pituitary adenoma predisposition (PAP), a recent discovery based on genetic studies in Northern Finland. In this population, a founder mutation explained a significant proportion of all acromegaly cases. Typically, PAP patients were of a young age at diagnosis but did not display a strong family history of pituitary adenomas. To evaluate the role of AIP in pituitary adenoma susceptibility in other populations and to gain insight into patient selection for molecular screening of the condition, we investigated the possible contribution of AIP mutations in pituitary tumorigenesis in patients from Europe and the United States. A total of 460 patients were investigated by AIP sequencing: young acromegaly patients, unselected acromegaly patients, unselected pituitary adenoma patients, and endocrine neoplasia-predisposition patients who were negative for MEN1 mutations. Nine AIP mutations were identified. Because many of the patients displayed no family history of pituitary adenomas, detection of the condition appears challenging. Feasibility of AIP immunohistochemistry (IHC) as a prescreening tool was tested in 50 adenomas: 12 AIP mutation-positive versus 38 mutation-negative pituitary tumors. AIP IHC staining levels proved to be a useful predictor of AIP status, with 75% sensitivity and 95% specificity for germ-line mutations. AIP contributes to PAP in all studied populations. AIP IHC, followed by genetic counseling and possible AIP mutation analysis in IHC-negative cases, a procedure similar to the diagnostics of the Lynch syndrome, appears feasible in identification of PAP.

Treatment of acromegaly with the GH receptor antagonist pegvisomant in clinical practice: safety and efficacy evaluation from the German Pegvisomant Observational Study

OBJECTIVE

The GH receptor antagonist pegvisomant is a highly effective new treatment option in acromegaly. The German Pegvisomant Observational Study (GPOS) was started to monitor long-term safety and efficacy of pegvisomant as prescribed in clinical practice.

DESIGN

GPOS is an observational, multi-center, surveillance study, which comprises non-interventional data collection.

METHODS

Of the 229 patients included in the study, 90.4% had previous pituitary surgery, 43.2% were treated by radiation therapy, and 94.3% had previous medical therapy for acromegaly that had been discontinued mainly due to persistent IGF-I elevation or side effects. The intention-to-treat population included 177 patients with at least one post-baseline efficacy measurement.

RESULTS

IGF-I levels decreased from 1.75+/-0.91-fold the upper limit of normal at baseline to 1.05+/- 0.62 at the 6-month visit, 0.96+/-0.60 at the 12-month visit, and to 0.89+/-0.41-fold after 24 months (P<0.0001). Mean duration of pegvisomant therapy was 51.8+/-35.8 weeks (median=51.9 weeks). IGF-I was normalized in 64.4% at 6 months with a median dose of 15.0 mg/day, in 70.9% at 12 months, and in 76.3% at 24 months. Fasting glucose levels improved from 114.4+/-45.9 to 101.5+/- 42.8 mg/dl after 6 months (P<0.01) and to 100.6+/-33.2 mg/ml after 12 months (P<0.01). General physical condition measured by specific signs and symptoms score improved significantly. Adverse events occurring in >1% were injection site reactions in 7.4%, elevated liver enzymes (>3 times of normal) in 5.2% (3.1% spontaneously normalized during continued treatment), reported increase of pituitary tumor volume in 5.2% (which was verified in 3.1%), and headache in 1.7%.

CONCLUSIONS

Pegvisomant is generally well tolerated with a safety profile similar to that reported in clinical trials and can effectively reduce IGF-I in patients with acromegaly refractory to conventional therapy.

Pituitary adenomas

Pituitary adenomas are by far the most common sellar tumor and magnetic resonance imaging is the modality of choice for their detection and characterization. However, most of these neoplasms are asymptomatic and frequently incidentally visualized. One also has to be aware of common other incidental findings and normal age-related changes in the appearance of the gland. By convention, 10 mm is used as the size threshold to separate macroadenomas from microadenomas. For microadenomas, imaging is primarily used for lesion detection and localization, whereas with macroadenomas, the goal is to establish whether the mass represents a pituitary tumor or some other lesion and to precisely delineate its extent.