Efficacy and safety of 48 weeks of treatment with octreotide LAR in newly diagnosed acromegalic patients with macroadenomas: an open-label, multicenter, non-comparative study

Monotherapy with lanreotide depot for acromegaly: long-term clinical experience in a pituitary center

PURPOSE

Long-acting somatostatin analogs are one of the main classes of medical therapy used for acromegaly and most patients require ongoing treatment. Few studies have evaluated the long-term efficacy and safety of lanreotide depot beyond 2 years. The goal of this study was to provide a long-term longitudinal assessment of efficacy and safety of lanreotide depot in lanreotide responders compared to a surgically cured control group.

METHODS

In this retrospective longitudinal case-control study, patients with acromegaly receiving lanreotide depot monotherapy continuously for at least 24 months (N = 24) and surgically cured patients (N = 39) were compared. Serum IGF-1, pituitary MRIs, lanreotide dose, co-morbidities and adverse effects were assessed longitudinally.

RESULTS

In the lanreotide group, IGF-1 remained normal and unchanged over 6 years; comparable to the surgery only group. There was no difference in prevalence of normal IGF-1 between the lanreotide and surgery only groups at 6 months (100 vs. 97 %), 6 years (89 vs. 90 %) and at last follow-up (96 vs. 92 %). Tumor size remained stable (79 %) or decreased (21 %) in the lanreotide group. In the surgery only group, tumor size remained unchanged in all patients. Hemoglobin A1C did not differ between lanreotide and surgery only groups (baseline 5.8 vs. 6.1 %; last follow-up 6.0 vs. 5.7 %). Two (8 %) of the lanreotide and none of the surgery only group developed new diabetes mellitus.

CONCLUSION

Lanreotide depot maintains normalization of IGF-1 in 89 % of responders after 6 years, comparable to surgically cured controls, and controlled tumor size in all without significant adverse effects.

Surgical interventions and medical treatments in treatment-naïve patients with acromegaly: systematic review and meta-analysis

CONTEXT

Acromegaly is usually treated with surgery as a first-line treatment, although medical therapy has also been used as an alternative primary treatment.

OBJECTIVE

We conducted a systematic review and meta-analysis to synthesize the existing evidence comparing these two approaches in treatment-naïve patients with acromegaly.

DATA SOURCES

This study performed a comprehensive search in multiple databases, including Medline, EMBASE, and Scopus from early inception through April 2014.

STUDY SELECTION

The study used original controlled and uncontrolled studies that enrolled patients with acromegaly to receive either surgical treatment or medical treatment as their first-line treatment.

DATA EXTRACTION

Reviewers extracted data independently and in duplicates. Because of the noncomparative nature of the available studies, we modified the Newcastle-Ottawa Scale to assess the quality of included studies. Outcomes evaluated were biochemical remission and change in IGF-1 or GH levels. We pooled outcomes using the random-effects model.

DATA SYNTHESIS

The final search yielded 35 studies enrolling 2629 patients. Studies were noncomparative series with a follow-up range of 6-360 months. Compared with medical therapy, surgery was associated with a higher remission rate (67% vs 45%; P = .02). Surgery had higher remission rates at longer follow-up periods (≥ 24 mo) (66% vs 44%; P = .04) but not the shorter follow-up periods (≤ 6 mo) (37% vs 26%; P = .22) [Corrected].Surgery had higher remission rates in the follow-up levels of GH (65% vs 46%; P = .05). In one study, the IGF-1 level was reduced more with surgery compared with medical treatment (-731 μg/L vs -251 μg/L; P = .04). Studies in which surgery was performed by a single operator reported a higher remission rate than those with multiple operators (71% vs 47%; P = .002).

CONCLUSIONS

Surgery may be associated with higher remission rate; however, the confidence in such evidence is very low due to the noncomparative nature of the studies, high heterogeneity, and imprecision.

Octreotide for acromegaly treatment: a reappraisal

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

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.

Octreotide long-acting repeatable for acromegaly

Acromegaly remains a therapeutic challenge for the endocrinologist. Among the available therapeutic options, octreotide long-acting repeatable (Sandostatin(®) LAR(®), Novartis) plays a chief role, both as a primary therapy and as an adjuvant treatment after unsuccessful surgery. A plethora of papers and a meta-analysis have demonstrated its efficacy in: control of clinical picture; achievement of safe growth hormone and normal age-matched IGF-I levels (both factors associated with restoration of normal life expectancy) in 60-70% of patients; control of tumor volume (with real shrinkage in over half of cases); and halt or reversal of most acromegaly-associated comorbidities. Treatment is well tolerated in most patients and can be safely prolonged for many years if required.

Role of SST, CORT and ghrelin and its receptors at the endocrine pancreas

Somatostatin (SST), cortistatin (CORT), and its receptors (sst1-5), and ghrelin and its receptors (GHS-R) are two highly interrelated neuropeptide systems with a broad range of overlapping biological actions at central, cardiovascular, and immune levels among others. Besides their potent regulatory role on GH release, its endocrine actions are highlighted by SST/CORT and ghrelin influence on insulin secretion, glucose homeostasis, and insulin resistance. Interestingly, most components of these systems are expressed at the endocrine pancreas and are actively involved in the modulation of pancreatic islet function and, consequently influence glucose homeostasis. In addition, some of them also participate in islet survival and regeneration. Furthermore, under severe metabolic condition as well as in endocrine pathologies, their expression profile is severely deregulated. These findings suggest that SST/CORT and ghrelin systems could play a relevant role in pancreatic function under metabolic and endocrine pathologies. Accordingly, these systems have been therapeutically targeted for the prevention or amelioration of certain metabolic conditions (obesity) as well as for tumor growth inhibition and/or hormonal regulation in endocrine pathologies (neuroendocrine tumors). This review focuses on the interrelationship between SST/CORT and ghrelin systems and their role in severe metabolic conditions and some endocrine disorders.

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

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

Quantification of day-to-day variability in growth hormone levels in acromegaly

Growth hormone (GH) measurements are routinely used for important treatment decisions in patients with acromegaly, yet their reliability is affected by numerous factors including assay precision and variability, sampling intensity, and hormone pulsatility. The day-to-day variation in GH in acromegaly has not been studied. This study quantified the magnitude of day-to-day GH variability in patients with acromegaly by performing an analysis of previously obtained plasma GH profiles. The analysis was performed at the Michigan Clinical Research Unit at the University of Michigan. A total of nine 48 h Q10 min GH profiles obtained in nine patients with active acromegaly were examined. The study was planned after data collection and analysis was conducted using Altman-Bland methods. Day 1 vs. Day 2 values were examined. 95% confidence intervals of the D2 vs. D1 ratios were calculated on all individual subject data as well as on a single 0800 h GH sample and composite mean data for 2-, 5-, 9-, and 24-h sampling protocols. Confidence interval range was 0.66-1.50 for the 0800 h sample and was similar for all sampling protocols except somewhat more narrow for the 24-h sampling (0.75-1.32). Daily variations in GH levels introduce an additional confounding element when using a single GH level or even daily GH curves to assess a patient's GH milieu. It may have an impact on result interpretation and subsequent treatment decisions especially when GH results are considered borderline.

A consensus on criteria for cure of acromegaly

OBJECTIVE

The Acromegaly Consensus Group met in April 2009 to revisit the guidelines on criteria for cure as defined in 2000.

PARTICIPANTS

Participants included 74 neurosurgeons and endocrinologists with extensive experience of treating acromegaly. EVIDENCE/CONSENSUS PROCESS: Relevant assays, biochemical measures, clinical outcomes, and definition of disease control were discussed, based on the available published evidence, and the strength of consensus statements was rated.

CONCLUSIONS

Criteria to define active acromegaly and disease control were agreed, and several significant changes were made to the 2000 guidelines. Appropriate methods of measuring and achieving disease control were summarized.

Effects of initial therapy for five years with somatostatin analogs for acromegaly on growth hormone and insulin-like growth factor-I levels, tumor shrinkage, and cardiovascular disease: a prospective study

OBJECTIVE

The objective of the study was to evaluate the efficacy of 5 yr of depot somatostatin analogs (SSAs) as first-line therapy in acromegaly.

OUTCOME MEASURES

Primary measures were fasting GH 2.5 microg/liter or less and IGF-I normalized for age and tumor shrinkage. Secondary measures were control of hypertension, arrhythmias, left ventricular hypertrophy, diastolic and systolic dysfunction, and change in lipid and glucose profile.

PATIENTS

Patients included 45 de novo patients (18 women and 27 men, aged 20-82 yr); 28 were treated with octreotide-long-acting release and 17 with lanreotide.

RESULTS

GH was controlled in 100% and IGF-I levels in 97.8%, tumor shrinkage was 74.9 +/- 22.1 and 78.2+/-14.5%, in the octreotide-long-acting release and lanreotide groups, respectively. There was a significant improvement in the prevalence of hypertension (from 46.7 to 22.2%, P = 0.027), arrhythmias (from 17.8% to zero, P = 0.01), left ventricular hypertrophy (from 82.2 to 42.2%, P < 0.0001), diastolic dysfunction (from 60.0 to 15.6%, P < 0.0001), systolic dysfunction (from 40.0 to 4.4%, P < 0.0001), and hypertriglyceridemia (from 40.0 to 4.4%, P < 0.0001). The prevalence of impaired glucose tolerance (IGT; from 28.9 to 20.0%. P = 0.46) and diabetes mellitus (from 22.4 to 31.1%, P = 0.64) did not change.

CONCLUSIONS

In patients with severe comorbidities and those who refuse surgery, 5 yr of exclusive SSA therapy induce successful control of GH and IGF-I; tumor shrinkage (by median 80%), and improvement of hypertension, cardiac performance; and dyslipidemia. No patient was withdrawn from treatment because of side effects, and glucose tolerance was stable. We suggest that first-line SSA treatment may be safely continued in patients with acromegaly, according to an individual patient's indications and preferences.

Control of IGF-I levels with titrated dosing of lanreotide Autogel over 48 weeks in patients with acromegaly

BACKGROUND

An essential criterion for control of acromegaly is normalization of IGF-I levels. Somatostatin analogues act to suppress IGF-I and GH levels.

OBJECTIVE

To assess the efficacy and safety of 48 weeks titrated dosing of lanreotide Autogel.

DESIGN

Open-label, multicentre, phase III, 48-week trial.

METHODS

Patients with active acromegaly (IGF-I levels > 1.3 times upper limit of age-adjusted normal range) were recruited. Twelve injections of lanreotide Autogel were given at 28-day intervals: during the 16-week fixed-dose phase, patients received 90 mg; in the 32-week dose-titration phase, patients received 60, 90 or 120 mg according to GH and IGF-I levels. Intention-to-treat analysis was performed to determine the proportion of patients with normalized age-adjusted IGF-I levels at study end. Secondary evaluations included GH levels, clinical acromegaly signs and safety.

RESULTS

Fifty-seven of 63 patients completed the study. Lanreotide Autogel resulted in normalized age-adjusted IGF-I levels in 27 patients (43%, 95% CI 31-55). Mean GH levels decreased from 6.2 to 1.5 microg/l at study end, with 53 of 62 patients (85%) having GH levels < or = 2.5 microg/l (95% CI 76.7-94.3) and 28 of 62 patients (45%) with levels < 1 microg/l (95% CI 32.8-57.6). Twenty-four (38%) had both normal IGF-I levels and GH levels < or = 2.5 microg/l. Acromegaly symptoms reduced significantly in most patients throughout the study. The most common adverse events were gastrointestinal, as expected for somatostatin analogues.

CONCLUSIONS

Using IGF-I as primary end-point, 48 weeks lanreotide Autogel treatment, titrated for optimal hormonal control, controlled IGF-I and GH levels effectively, reduced acromegaly symptoms and was well tolerated.

Assessment of the magnitude of growth hormone hypersecretion in active acromegaly: reliability of different sampling models

CONTEXT

The pulsatility of GH secretion in acromegaly poses difficulty in ascertaining true daily GH milieu in patients with this disease. Intensive GH sampling [every 10-20 (Q10-20) min for 24 h] is not practical in clinical practice.

OBJECTIVE

Our objective was to ascertain reliability of abbreviated sampling protocols to reflect true 24-h mean GH concentrations in patients with acromegaly.

DESIGN

An analysis of previously obtained plasma GH profiles was performed.

SETTING

The analysis was performed at the General Clinical Research Center at the University of Michigan.

PATIENTS

A total of 115 GH profiles obtained in 94 patients with active acromegaly were examined.

INTERVENTION

Frequent blood sampling, i.e. Q10-20 min for 24 h, was performed.

MAIN OUTCOME MEASURES

Concordance of 24-h mean GH concentrations derived from Q10- to 20-min samplings with abbreviated GH sampling schedules was performed. The study was planned after data collection.

RESULTS

All abbreviated schedules of GH sampling correlated well with the true 24-h plasma GH means (i.e. Q10- to 20-min sampling) (R = 0.93-0.98; P < 0.0001 for all). In the GH range more than 20 microg/liter, only 5 and 9-h means had R values more than 0.9. Single GH concentrations less than 1 microg/liter had a positive predictive value of only 0.29, and those with less than 2.5 microg/liter had a positive predictive value of 0.67 vs. their corresponding 24-h mean GH values of the same magnitude.

CONCLUSIONS

The intensity of GH sampling in patients with acromegaly may vary depending on the nature of the required information. Investigators and clinicians should be aware of the limitations of the abbreviated GH sampling protocols in acromegaly.

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.

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

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