Sandostatin LAR: a promising therapeutic tool in the management of acromegalic patients

Surgical and non-surgical interventions for primary and salvage treatment of growth hormone-secreting pituitary adenomas in adults

BACKGROUND

Growth hormone (GH)-secreting pituitary adenoma is a severe endocrine disease. Surgery is the currently recommended primary therapy for patients with GH-secreting tumours. However, non-surgical therapy (pharmacological therapy and radiation therapy) may be performed as primary therapy or may improve surgical outcomes.

OBJECTIVES

To assess the effects of surgical and non-surgical interventions for primary and salvage treatment of GH-secreting pituitary adenomas in adults.

SEARCH METHODS

We searched CENTRAL, MEDLINE, WHO ICTRP, and ClinicalTrials.gov. The date of the last search of all databases was 1 August 2022. We did not apply any language restrictions.

SELECTION CRITERIA

Randomised controlled trials (RCTs) and quasi-RCTs of more than 12 weeks' duration, reporting on surgical, pharmacological, radiation, and combination interventions for GH-secreting pituitary adenomas in any healthcare setting.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened titles and abstracts for relevance, screened for inclusion, completed data extraction, and performed a risk of bias assessment. We assessed studies for overall certainty of the evidence using GRADE. We estimated treatment effects using random-effects meta-analysis. We expressed results as risk ratios (RR) for dichotomous outcomes together with 95% confidence intervals (CI) or mean differences (MD) for continuous outcomes, or in descriptive format when meta-analysis was not possible.

MAIN RESULTS

We included eight RCTs that evaluated 445 adults with GH-secreting pituitary adenomas. Four studies reported that they included participants with macroadenomas, one study included a small number of participants with microadenomas. The remaining studies did not specify tumour subtypes. Studies evaluated surgical therapy alone, pharmacological therapy alone, or combination surgical and pharmacological therapy. Methodological quality varied, with many studies providing insufficient information to compare treatment strategies or accurately judge the risk of bias. We identified two main comparisons, surgery alone versus pharmacological therapy alone, and surgery alone versus pharmacological therapy and surgery combined. Surgical therapy alone versus pharmacological therapy alone Three studies with a total of 164 randomised participants investigated this comparison. Only one study narratively described hyperglycaemia as a disease-related complication. All three studies reported adverse events, yet only one study reported numbers separately for the intervention arms; none of the 11 participants were observed to develop gallbladder stones or sludge on ultrasonography following surgery, while five of 11 participants experienced any biliary problems following pharmacological therapy (RR 0.09, 95% CI 0.01 to 1.47; 1 study, 22 participants; very low-certainty evidence). Health-related quality of life was reported to improve similarly in both intervention arms during follow-up. Surgery alone compared to pharmacological therapy alone may slightly increase the biochemical remission rate from 12 weeks to one year after intervention, but the evidence is very uncertain; 36/78 participants in the surgery-alone group versus 15/66 in the pharmacological therapy group showed biochemical remission. The need for additional surgery or non-surgical therapy for recurrent or persistent disease was described for single study arms only. Surgical therapy alone versus preoperative pharmacological therapy and surgery Five studies with a total of 281 randomised participants provided data for this comparison. Preoperative pharmacological therapy and surgery may have little to no effect on the disease-related complication of a difficult intubation (requiring postponement of surgery) compared to surgery alone, but the evidence is very uncertain (RR 2.00, 95% CI 0.19 to 21.34; 1 study, 98 participants; very low-certainty evidence). Surgery alone may have little to no effect on (transient and persistent) adverse events when compared to preoperative pharmacological therapy and surgery, but again, the evidence is very uncertain (RR 1.23, 95% CI 0.75 to 2.03; 5 studies, 267 participants; very low-certainty evidence). Concerning biochemical remission, surgery alone compared to preoperative pharmacological therapy and surgery may not increase remission rates up until 16 weeks after surgery; 23 of 134 participants in the surgery-alone group versus 51 of 133 in the preoperative pharmacological therapy and surgery group showed biochemical remission. Furthermore, the very low-certainty evidence did not suggest benefit or detriment of preoperative pharmacological therapy and surgery compared to surgery alone for the outcomes 'requiring additional surgery' (RR 0.48, 95% CI 0.05 to 5.06; 1 study, 61 participants; very low-certainty evidence) or 'non-surgical therapy for recurrent or persistent disease' (RR 1.22, 95% CI 0.65 to 2.28; 2 studies, 100 participants; very low-certainty evidence). None of the included studies measured health-related quality of life. None of the eight included studies measured disease recurrence or socioeconomic effects. While three of the eight studies reported no deaths to have occurred, one study mentioned that overall, two participants had died within five years of the start of the study.

AUTHORS' CONCLUSIONS

Within the context of GH-secreting pituitary adenomas, patient-relevant outcomes, such as disease-related complications, adverse events and disease recurrence were not, or only sparsely, reported. When reported, we found that surgery may have little or no effect on the outcomes compared to the comparator treatment. The current evidence is limited by the small number of included studies, as well as the unclear risk of bias in most studies. The high uncertainty of evidence significantly limits the applicability of our findings to clinical practice. Detailed reporting on the burden of recurrent disease is an important knowledge gap to be evaluated in future research studies. It is also crucial that future studies in this area are designed to report on outcomes by tumour subtype (that is, macroadenomas versus microadenomas) so that future subgroup analyses can be conducted. More rigorous and larger studies, powered to address these research questions, are required to assess the merits of neoadjuvant pharmacological therapy or first-line pharmacotherapy.

Self-Assembling Peptide-Based Functional Biomaterials

Peptides can self-assemble into various hierarchical nanostructures through noncovalent interactions and form functional materials exhibiting excellent chemical and physical properties, which have broad applications in bio-/nanotechnology. The self-assembly mechanism, self-assembly morphology of peptide supramolecular architecture and their various applications, have been widely explored which have the merit of biocompatibility, easy preparation, and controllable functionality. Herein, we introduce the latest research progress of self-assembling peptide-based nanomaterials and review their applications in biomedicine and optoelectronics, including tissue engineering, anticancer therapy, biomimetic catalysis, energy harvesting. We believe that this review will inspire the rational design and development of novel peptide-based functional bio-inspired materials in the future.

Maintenance of Acromegaly Control in Patients Switching From Injectable Somatostatin Receptor Ligands to Oral Octreotide

PURPOSE

The phase 3 CHIASMA OPTIMAL trial (NCT03252353) evaluated efficacy and safety of oral octreotide capsules (OOCs) in patients with acromegaly who previously demonstrated biochemical control while receiving injectable somatostatin receptor ligands (SRLs).

METHODS

In this double-blind study, patients (N = 56) stratified by prior SRL dose were randomly assigned 1:1 to OOC or placebo for 36 weeks. The primary end point was maintenance of biochemical control at the end of treatment (mean insulin-like growth factor 1 [IGF-1] ≤ 1.0 × upper limit of normal [ULN]; weeks 34 and 36). Time to loss of IGF-1 response and proportion requiring reversion to injectable SRLs were assessed as broader control measures.

RESULTS

Mean IGF-1 measurements were 0.80 and 0.97 × ULN for OOC and 0.84 and 1.69 × ULN for placebo, at baseline and end of treatment, respectively. Mean growth hormone (GH) changed from 0.66 to 0.60 ng/mL for OOCs and 0.90 to 2.57 ng/mL for placebo. Normalization of IGF-1 levels (≤ 1.0 × ULN) was maintained in 58.2% for OOCs vs 19.4% for placebo (P = .008); GH levels were maintained (< 2.5 ng/mL) in 77.7% for OOC vs 30.4% for placebo (P = .0007). Median time to loss of response (IGF-1 > 1.0 or ≥ 1.3 × ULN definitions) for patients receiving placebo was 16 weeks; for patients receiving OOCs, it was not reached for both definitions during the 36-week trial (P < .0001). Of the patients in the OOC group, 75% completed the trial on oral therapy. The OOC safety profile was consistent with previous SRL experience.

CONCLUSIONS

OOCs may be an effective therapy for patients with acromegaly who previously were treated with injectable SRLs.

Targeting the Somatostatin Receptor 2 with the Miniaturized Drug Conjugate, PEN-221: A Potent and Novel Therapeutic for the Treatment of Small Cell Lung Cancer

Small cell lung cancer (SCLC) is an aggressive neuroendocrine carcinoma with a 95% mortality rate with no improvement to treatment in decades, and new therapies are desperately needed. PEN-221 is a miniaturized peptide-drug conjugate (∼2 kDa) designed to target SCLC via a Somatostatin Receptor 2 (SSTR2)-targeting ligand and to overcome the high proliferation rate characteristic of this disease by using the potent cytotoxic payload, DM1. SSTR2 is an ideal target for a drug conjugate, as it is overexpressed in SCLC with limited normal tissue expression. In vitro, PEN-221 treatment of SSTR2-positive cells resulted in PEN-221 internalization and receptor-dependent inhibition of cellular proliferation. In vivo, PEN-221 exhibited rapid accumulation in SSTR2-positive SCLC xenograft tumors with quick clearance from plasma. Tumor accumulation was sustained, resulting in durable pharmacodynamic changes throughout the tumor, as evidenced by increases in the mitotic marker of G₂-M arrest, phosphohistone H3, and increases in the apoptotic marker, cleaved caspase-3. PEN-221 treatment resulted in significant antitumor activity, including complete regressions in SSTR2-positive SCLC xenograft mouse models. Treatment was effective using a variety of dosing schedules and at doses below the MTD, suggesting flexibility of dosing schedule and potential for a large therapeutic window in the clinic. The unique attributes of the miniaturized drug conjugate allowed for deep tumor penetration and limited plasma exposure that may enable long-term dosing, resulting in durable tumor control. Collectively, these data suggest potential for antitumor activity of PEN-221 in patients with SSTR2-positive SCLC.

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.

Biological and Biochemical Basis of the Differential Efficacy of First and Second Generation Somatostatin Receptor Ligands in Neuroendocrine Neoplasms

Endogenous somatostatin shows anti-secretory effects in both physiological and pathological settings, as well as inhibitory activity on cell growth. Since somatostatin is not suitable for clinical practice, researchers developed synthetic somatostatin receptor ligands (SRLs) to overcome this limitation. Currently, SRLs represent pivotal tools in the treatment algorithm of neuroendocrine tumors (NETs). Octreotide and lanreotide are the first-generation SRLs developed and show a preferential binding affinity to somatostatin receptor (SST) subtype 2, while pasireotide, which is a second-generation SRL, has high affinity for multiple SSTs (SST₅ > SST₂ > SST₃ > SST₁). A number of studies demonstrated that first-generation and second-generation SRLs show distinct functional properties, besides the mere receptor affinity. Therefore, the aim of the present review is to critically review the current evidence on the biological effects of SRLs in pituitary adenomas and neuroendocrine tumors, by mainly focusing on the differences between first-generation and second-generation ligands.

Growth hormone-secreting pituitary macroadenoma presenting concurrently with non-Hodgkin's lymphoma and responding to doxorubicin treatment: case report and review of the literature

We present a case report of a patient who presented with nausea and vomiting, as well as acromegalic features. Following testing, a pituitary adenoma and mediastinal non-Hodgkin's lymphoma were diagnosed. Following two cycles of R-CHOP chemotherapy, imaging showed significant decrease in size of the sellar tumor. Following resection of tumor, both frozen and permanent section revealed only necrotic material. Further research into the potential utility of doxorubicin for the treatment of recurrent or refractory pituitary adenomas may be warranted.

Medical Therapy of Gastrointestinal Neuroendocrine Tumors

Intestinal neuroendocrine tumors (NETs) constitute a heterogeneous group with duodenal, small intestinal, colonic and rectal NETs. They constitute more than half of all NETs, with the highest frequencies in the rectum, small intestine, and colon. The tumor biology varies with the location of the primary tumor as well as with the grade and staging of the tumor. Small intestinal NETs usually present low proliferation and are treated in the first line with somatostatin analogs according to current guidelines. If progression occurs, one can add interferon alpha or change the treatment to everolimus. Peptide receptor radionuclide therapy (PRRT) with Lutetium¹⁷⁷-DOTATATE can be an option in the future after registration of the compound. Rectal tumors are usually small when they metastasize; they can be treated with somatostatin analogs but more so with PRRT, while another option is of course everolimus. Colonic NETs are more aggressive than the rest of intestinal NETs and will be treated with everolimus, sometimes in combination with somatostatin analogs based on positive scintigraphy. Another option is a cytotoxic agent such as streptozotocin plus 5-fluorouracil (5-FU) or temozolomide plus capecitabine. The most aggressive tumors, i.e. neuroendocrine carcinoma G3, are treated with a platin-based therapy plus etoposide; if they present with a lower proliferation, i.e. <50%, temozolomide plus capecitabine plus bevacizumab can also be attempted. Duodenal NETs are mostly treated similar to pancreatic NETs, either with cytotoxic agents, streptozotocin plus 5-FU, or temozolomide plus capecitabine, or with targeted agents such as everolimus.

Update on the use of oral octreotide therapy for acromegaly

Somatostatin analogs are most commonly used in pharmacological treatment of acromegaly. Pegvisomant and dopamine agonists are alternatives, which are used to a lesser extent. Dopamine agonists are the only orally applicable medication but are less effective than the other options. For a large number of patients, life-long pharmacotherapy has to be applied and frequent injections represent a reduction of quality of life for many of them. Areas covered: Recently published evidence for the use of oral octreotide therapy for acromegaly. Expert commentary: Oral octreotide is a novel and effective treatment for acromegaly and the side effects have been shown to be comparable to the injectable SSAs. The combination with a transient permeability enhancer allows intestinal permeation but also enables molecules with a size <70 kDa to pass transiently. This does not seem to have an acute or subacute consequence, but the long-term effect is still elusive. Therefore, more long-term trials are desirable.

Interpreting biochemical control response rates with first-generation somatostatin analogues in acromegaly

CONTEXT

The somatostatin analogues octreotide LAR and lanreotide Autogel have been evaluated for the treatment of acromegaly in numerous clinical trials, with considerable heterogeneity in reported biochemical response rates. This review examines and attempts to account for these differences in response rates reported in the literature.

EVIDENCE ACQUISITION

PubMed was searched for English-language studies of a minimum duration of 24 weeks that evaluated ≥10 patients with acromegaly treated with octreotide LAR or lanreotide Autogel from 1990 to March 2015 and reported GH and/or IGF-1 data as the primary objective of the study.

EVIDENCE SYNTHESIS

Of the 190 clinical trials found, 18 octreotide LAR and 15 lanreotide Autogel studies fulfilled the criteria for analysis. It is evident from the protocols of these studies that multiple factors are capable of impacting on reported response rates. Prospective studies reporting an intention-to-treat analysis that evaluated medically naïve patients and used the composite endpoint of both GH and IGF-1 control were associated with lower response rates. The use of non-composite biochemical control endpoints, heterogeneous patient populations, analyses that exclude treatment non-responders, assay variability and prior responsiveness to medical therapy are just a few of the factors identified that likely contribute to higher success rates.

CONCLUSIONS

The wide range of reported response rates with somatostatin analogues may be confusing and could lead to misinterpretation by both the patient and the physician in certain situations. Understanding the factors that potentially drive the variation in response rates should allow clinicians to better gauge treatment expectations in specific patients.

Patient-reported outcomes of parenteral somatostatin analogue injections in 195 patients with acromegaly

BACKGROUND

Long-acting somatostatin analogues delivered parenterally are the most widely used medical treatment in acromegaly. This patient-reported outcomes survey was designed to assess the impact of chronic injections on subjects with acromegaly.

METHODS

The survey was conducted in nine pituitary centres in Germany, UK and The Netherlands. The questionnaire was developed by endocrinologists and covered aspects of acromegaly symptoms, injection-related manifestations, emotional and daily life impact, treatment satisfaction and unmet medical needs.

RESULTS

In total, 195 patients participated, of which 112 (57%) were on octreotide (Sandostatin LAR) and 83 (43%) on lanreotide (Somatuline Depot). The majority (>70%) of patients reported acromegaly symptoms despite treatment. A total of 52% of patients reported that their symptoms worsen towards the end of the dosing interval. Administration site pain lasting up to a week following injection was the most frequently reported injection-related symptom (70% of patients). Other injection site reactions included nodules (38%), swelling (28%), bruising (16%), scar tissue (8%) and inflammation (7%). Injection burden was similar between octreotide and lanreotide. Only a minority of patients received injections at home (17%) and 5% were self-injecting. Over a third of patients indicated a feeling of loss of independence due to the injections, and 16% reported repeated work loss days. Despite the physical, emotional and daily life impact of injections, patients were satisfied with their treatment, yet reported that modifications that would offer major improvement over current care would be 'avoiding injections' and 'better symptom control'.

CONCLUSION

Lifelong injections of long-acting somatostatin analogues have significant burden on the functioning, well-being and daily lives of patients with acromegaly.

Safety and efficacy of oral octreotide in acromegaly: results of a multicenter phase III trial

BACKGROUND

A novel oral octreotide formulation was tested for efficacy and safety in a phase III, multicenter, open-label, dose-titration, baseline-controlled study in patients with acromegaly.

METHODS

We enrolled 155 complete or partially controlled patients (IGF-1 <1.3 × upper limit of normal [ULN], and 2-h integrated GH <2.5 ng/mL) receiving injectable somatostatin receptor ligand (SRL) for ≥ 3 months. Subjects were switched to 40 mg/d oral octreotide capsules (OOCs), and the dose escalated to 60 and then up to 80 mg/d to control IGF-1. Subsequent fixed doses were maintained for a 7-month core treatment, followed by a voluntary 6-month extension.

RESULTS

Of 151 evaluable subjects initiating OOCs, 65% maintained response and achieved the primary endpoint of IGF-1 <1.3 × ULN and mean integrated GH <2.5 ng/mL at the end of the core treatment period and 62% at the end of treatment (up to 13 mo). The effect was durable, and 85 % of subjects initially controlled on OOCs maintained this response up to 13 months. When controlled on OOCs, GH levels were reduced compared to baseline, and acromegaly-related symptoms improved. Of 102 subjects completing the core treatment, 86% elected to enroll in the 6-month extension. Twenty-six subjects who were considered treatment failures (IGF-1 ≥ 1.3 × ULN) terminated early, and 23 withdrew for adverse events, consistent with those known for octreotide or disease related.

CONCLUSIONS

OOC, an oral therapeutic peptide, achieves efficacy in controlling IGF-1 and GH after switching from injectable SRLs for up to 13 months, with a safety profile consistent with approved SRLs. OOC appears to be effective and safe as an acromegaly monotherapy.

Pasireotide versus octreotide in acromegaly: a head-to-head superiority study

CONTEXT

Biochemical control reduces morbidity and increases life expectancy in patients with acromegaly. With current medical therapies, including the gold standard octreotide long-acting-release (LAR), many patients do not achieve biochemical control.

OBJECTIVE

Our objective was to demonstrate the superiority of pasireotide LAR over octreotide LAR in medically naive patients with acromegaly.

DESIGN AND SETTING

We conducted a prospective, randomized, double-blind study at 84 sites in 27 countries.

PATIENTS

A total of 358 patients with medically naive acromegaly (GH >5 μg/L or GH nadir ≥1 μg/L after an oral glucose tolerance test (OGTT) and IGF-1 above the upper limit of normal) were enrolled. Patients either had previous pituitary surgery but no medical treatment or were de novo with a visible pituitary adenoma on magnetic resonance imaging.

INTERVENTIONS

Patients received pasireotide LAR 40 mg/28 days (n = 176) or octreotide LAR 20 mg/28 days (n = 182) for 12 months. At months 3 and 7, titration to pasireotide LAR 60 mg or octreotide LAR 30 mg was permitted, but not mandatory, if GH ≥2.5μg/L and/or IGF-1 was above the upper limit of normal.

MAIN OUTCOME MEASURE

The main outcome measure was the proportion of patients in each treatment arm with biochemical control (GH <2.5 μg/L and normal IGF-1) at month 12.

RESULTS

Biochemical control was achieved by significantly more pasireotide LAR patients than octreotide LAR patients (31.3% vs 19.2%; P = .007; 35.8% vs 20.9% when including patients with IGF-1 below the lower normal limit). In pasireotide LAR and octreotide LAR patients, respectively, 38.6% and 23.6% (P = .002) achieved normal IGF-1, and 48.3% and 51.6% achieved GH <2.5 μg/L. 31.0% of pasireotide LAR and 22.2% of octreotide LAR patients who did not achieve biochemical control did not receive the recommended dose increase. Hyperglycemia-related adverse events were more common with pasireotide LAR (57.3% vs 21.7%).

CONCLUSIONS

Pasireotide LAR demonstrated superior efficacy over octreotide LAR and is a viable new treatment option for acromegaly.

The place of medical treatment of acromegaly: current status and perspectives

INTRODUCTION

Acromegaly is characterized by elevated growth hormone (GH) and insulin-like growth factor-I (IGF-I) levels and by progressive somatic disfigurement and systemic manifestations, which lead to a mortality rate higher than the general population. Therefore, diagnosis and properly treatment should be performed as soon as possible.

AREAS COVERED

This article focuses on the state of the art of acromegaly medical treatment. Somatostatin analogs, dopamine agonists and GH receptor antagonist were reviewed. Somatostatin analogs, the first-choice pharmacotherapy, can be used as primary or pre-operative treatment or as secondary therapy after failed surgery. Dopamine agonists have been used in patients with slightly elevated hormone levels and/or mixed GH/prolactin adenomas. Pegvisomant is indicated for resistant to somatostatin analogs/dopamine agonists. Combined treatment is also an option for resistant cases. Other non-conventional therapies and perspectives of treatment were also been discussed.

EXPERT OPINION

The control of disease activity in acromegaly is of paramount importance. Medical treatment is an important option for cases in which surgery was unsuccessful or not indicated. Despite the achievements in medical treatment, somatotropic tumor aggressiveness and/or resistance to the drugs currently available remain a concern. Therefore, novel therapy targets based on molecular pathogenesis of GH-secreting tumors are currently in development, aiming at fulfilling this important gap.

Desensitization treatment for hypersensitivity reaction to octreotide in an acromegalic patient

Octreotide is widely used as medical therapy for acromegaly. It is known to markedly reduce growth hormone levels, improve symptoms and reduce tumor size. Common side effects include gastrointestinal symptoms, hepatobiliary disorders, dizziness, headaches, bradycardia, hyperglycemia or hypoglycemia and thyroid dysfunction. Although urticaria, allergy/hypersensitivity reactions and anaphylaxis have been noted as possible adverse reactions, there is a lack of data showing a causal relationship between octreotide and hypersensitivity reactions and there is no information on management when continued use of this medication is essential. We now report a case of a 60 year old male with acromegaly who had presented with a cutaneous hypersensitivity reaction to octreotide. In addition he failed treatment with surgery, radiation, and dopamine agonist and could no longer afford to continue treatment with pegvisomant. The patient underwent desensitization treatment for his octreotide allergy and was able to resume treatment without any further side effects. We believe this case represents the first report of successful desensitization treatment for octreotide allergy in an acromegalic patient.

Meta-analysis on the effects of octreotide on tumor mass in acromegaly

BACKGROUND

The long-acting somatostatin analogue octreotide is used either as an adjuvant or primary therapy to lower growth hormone (GH) levels in patients with acromegaly and may also induce pituitary tumor shrinkage.

OBJECTIVE

We performed a meta-analysis to accurately assess the effect of octreotide on pituitary tumor shrinkage.

DATA SOURCES

A computerized Medline and Embase search was undertaken to identify potentially eligible studies.

STUDY ELIGIBILITY CRITERIA

Eligibility criteria included treatment with octreotide, availability of numerical metrics on tumor shrinkage and clear definition of a clinically relevant reduction in tumor size. Primary endpoints included the proportion of patients with tumor shrinkage and mean percentage reduction in tumor volume.

DATA EXTRACTION AND ANALYSIS

The electronic search identified 2202 articles. Of these, 41 studies fulfilling the eligibility criteria were selected for data extraction and analysis. In total, 1685 patients were included, ranging from 6 to 189 patients per trial. For the analysis of the effect of octreotide on pituitary tumor shrinkage a random effect model was used to account for differences in both effect size and sampling error.

RESULTS

Octreotide was shown to induce tumor shrinkage in 53.0% [95% CI: 45.0%-61.0%] of treated patients. In patients treated with the LAR formulation of octreotide, this increased to 66.0%, [95% CI: 57.0%-74.0%). In the nine studies in which tumor shrinkage was quantified, the overall weighted mean percentage reduction in tumor size was 37.4% [95% CI: 22.4%-52.4%], rising to 50.6% [95% CI: 42.7%-58.4%] with octreotide LAR.

LIMITATIONS

Most trials examined were open-label and had no control group.

CONCLUSIONS

Octreotide LAR induces clinically relevant tumor shrinkage in more than half of 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.

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.

Role of somatostatins in gastroenteropancreatic neuroendocrine tumor development and therapy

The incidence and prevalence of gastroenteropancreatic neuroendocrine tumors (GEP-NETs) have increased in the past 20 years. GEP-NETs are heterogeneous tumors, in terms of clinical and biological features, that originate from the pancreas or the intestinal tract. Some GEP-NETs grow very slowly, some grow rapidly and do not cause symptoms, and others cause hormone hypersecretion and associated symptoms. Most GEP-NETs overexpress receptors for somatostatins. Somatostatins inhibit the release of many hormones and other secretory proteins; their effects are mediated by G protein-coupled receptors that are expressed in a tissue-specific manner. Most GEP-NETs overexpress the somatostatin receptor SSTR2; somatostatin analogues are the best therapeutic option for functional neuroendocrine tumors because they reduce hormone-related symptoms and also have antitumor effects. Long-acting formulations of somatostatin analogues stabilize tumor growth over long periods. The development of radioactive analogues for imaging and peptide receptor radiotherapy has improved the management of GEP-NETs. Peptide receptor radiotherapy has significant antitumor effects, increasing overall survival times of patients with tumors that express a high density of SSTRs, particularly SSTR2 and SSTR5. The multi-receptor somatostatin analogue SOM230 (pasireotide) and chimeric molecules that bind SSTR2 and the dopamine receptor D2 are also being developed to treat patients with GEP-NETs. Combinations of radioactive labeled and unlabeled somatostatin analogues and therapeutics that inhibit other signaling pathways, such as mammalian target of rapamycin (mTOR) and vascular endothelial growth factor, might be the most effective therapeutics for GEP-NETs.

Octreotide LAR: safety and tolerability issues

BACKGROUND

Somatostatin analogues are the cornerstone in therapy of acromegaly and functioning neuroendocrine tumors. Long-acting retard formulations have improved patient survival and contributed considerably to quality of life. The first such compound was octreotide LAR ('long-acting release'), characterized by high affinity to somatostatin receptor subtypes 2 and 5, which has to be injected intramuscularly every 4 weeks.

OBJECTIVE

The aim was to screen all octreotide LAR-related literature and assess the compound's profile for safety and tolerability.

METHODS

An extensive literature search has been performed using the MEDLINE database to retrieve data from clinical studies evaluating the efficacy and tolerability of octreotide LAR.

RESULTS/CONCLUSION

Octreotide LAR is well tolerated; however, diarrhea and gallstone formation were identified as the main adverse events. Impairment of glucose homeostasis was a regular phenomenon, but its occurrence was unpredictable. General side effects such as headache, abdominal discomfort or fatigue were also reported. According to incidental case reports, administration during pregnancy appears to be safe for both mother and child; however, definitive evidence is missing. In addition, octreotide LAR has been evaluated for further indications including treatment of solid tumor entities, due to its antiproliferative effect. Currently, several compounds (lanreotide, SOM230) with a broader receptor spectrum are under evaluation and may improve treatment efficacy and lower incidence of side effects.

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.

Formulation and performance characterization of radio-sterilized "progestin-only" microparticles intended for contraception

The aim of this study was to formulate and characterize a microparticulate system of progestin-only contraceptive. Another objective was to evaluate the effect of gamma radio-sterilization on in vitro and in vivo drug release characteristics. Levonorgestrel (LNG) microspheres were fabricated using poly(lactide-co-glycolide) (PLGA) by a novel solvent evaporation technique. The formulation was optimized for drug/polymer ratio, emulsifier concentration, and process variables like speed of agitation and evaporation method. The drug to polymer ratio of 1:5 gave the optimum encapsulation efficiency. Speed of agitation influenced the spherical shape of the microparticles, lower speeds yielding less spherical particles. The speed did not have a significant influence on the drug payloads. A combination of stabilizers viz. methyl cellulose and poly vinyl alcohol with in-water solvent evaporation technique yielded microparticles without any free drug crystals on the surface. This aspect significantly eliminated the in vitro dissolution "burst effect". The residual solvent content was well within the regulatory limits. The microparticles passed the test for sterility and absence of pyrogens. In vitro dissolution conducted on the product before and after gamma radiation sterilization at 2.5 Mrad indicated no significant difference in the drug release patterns. The drug release followed zero-order kinetics in both static and agitation conditions of dissolution testing. The in vivo studies conducted in rabbits exhibited LNG release up to 1 month duration with drug levels maintained within the effective therapeutic window.

Fabrication, characterization and in vivo studies of biodegradable gamma sterilized injectable microparticles for contraception

A Levonorgestrel-loaded microparticulate system was developed with gelatin and bovine serum albumin using triple emulsion technique coupled with chemical cross-linking thermal rigidization method. The formulation was optimized for various formulation variables and process parameters. The microparticulate system was characterized by scanning electron microscopy, encapsulation efficiency, moisture content, IR, DSC, XRD, residual solvent content and evaluated for sterility, abnormal toxicity and absence of pyrogens. Microparticles were sterilized by gamma irradiation at 2.5 Mrad. The system was injected intramuscularly in rabbits and drug blood levels estimated using radioimmunoassay technique. An optimized drug to polymer ratio of 0.4:0.75 w/w gave drug encapsulation efficiency of about 40%. The in vitro drug release followed Higuchi square root kinetics. In in vivo studies the AUC0-t was found to be 12849.25 pg/mL.day(-1) with mean residence time calculated to be about 16 days and Kel of 0.02 day(-1). Levonorgestrel (LNG) levels were maintained between 200 and 400 pg/mL. The pharmacokinetic results indicate that LNG is released from the injectable microparticles for a period of one-month duration.

Efficacy of long-term lanreotide treatment in patients with acromegaly

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

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

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

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

CONTEXT

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

OBJECTIVE

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

DATA SOURCES

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

DATA COLLECTION

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

DATA SYNTHESIS

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

CONCLUSION

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

Somatostatin agonists for treatment of acromegaly

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

Medical therapy: options and uses

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

Acromegaly

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

A 12-month randomized crossover study on the effects of lanreotide Autogel and octreotide long-acting repeatable on GH and IGF-l in patients with acromegaly

BACKGROUND

Somatostatin analogues have been used successfully for the treatment of acromegaly but no randomized studies have compared the effects of lanreotide Autogel (LAN) and octreotide acetate long-acting repeatable (OCT).

OBJECTIVE

To compare the effect of LAN and OCT for the treatment of acromegaly in a randomized study design.

MATERIAL AND METHODS

Twelve acromegalic patients were included and 10 patients completed treatment with LAN or OCT for 6 months and were then switched to the opposite treatment modality for 6 months without a washout period in a randomized crossover design. GH and IGF-I profiles, clinical and biochemical evaluations were performed at 0, 4, 6, 10 and 12 months.

RESULTS

After 6 months of treatment, five patients had GH levels < 0.38 microg/l during both therapies. The remaining patients had GH levels > 0.38 microg/l during both LAN and OCT treatment. Four patients had normalized IGF-I levels during both treatment regimes. Two patients on LAN and one on OCT had normalized IGF-I levels during one treatment and not during the other. In three patients, IGF-I levels were elevated during both therapies. Four patients developed palpable nodules, two patients on LAN and two patients on OCT. Gastrointestinal complaints were seen in three patients during both therapies, in three patients only during LAN, and in one patient only during OCT. Two patients were withdrawn from the study because of serious adverse effects during LAN. After the study period, four patients preferred LAN and six patients preferred OCT treatment.

CONCLUSION

The effects of LAN and OCT therapy on GH and IGF-I levels were comparable, but 3/10 patients had different treatment efficacies and 6/10 had different side-effect profiles during the LAN and OCT treatment. These results indicate that a change from LAN to OCT or vice versa may be beneficial in some patients with treatment failure or side-effects.

Management of acromegaly: is there a role for primary medical therapy?

Acromegaly is a chronic, debilitating disease caused by chronic growth hormone (GH) hypersecretion which results in chronic medical comorbidities, poor quality of life and high mortality rates. Successful treatment can improve clinical signs and symptoms and normalize mortality rates. Over 95% of acromegaly is caused by a somatotroph adenoma of the pituitary, and the first-line treatment is generally transsphenoidal surgery, which can be curative in 50-60% of patients. Nonetheless, high rates of persistent acromegaly following surgery and the limited efficacy of radiation therapy necessitate chronic medical treatment for many patients. Somatostatin analogues have become the preferred first-line medical therapy for many practitioners, as they achieve better biochemical and direct tumor control than the dopamine agonists, and long-acting preparations make once monthly administration possible. Cabergoline, a dopamine agonist, offers a lower-cost option and may be effective in patients with a pituitary tumor that co-secretes GH and prolactin. Pegvisomant is a GH receptor antagonist that produces exceptional biochemical response rates but lacks any direct effects on the tumor, which may limit its effectiveness as life-long monotherapy. Combinations of these three drug classes have not been rigorously studied, and preliminary trials do not suggest improved clinical outcomes. While medical treatment options for acromegaly have significantly improved over the last 30 years, limitations remain, and a multi-specialty team approach is necessary for the effective long-term management of patients with acromegaly.

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

OBJECTIVE

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

DESIGN

Analytical, observational, open and prospective.

METHODS

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

RESULTS

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

CONCLUSION

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

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.

Efficacy of lanreotide Autogel administered every 4-8 weeks in patients with acromegaly previously responsive to lanreotide microparticles 30 mg: a phase III trial

OBJECTIVE AND DESIGN

Depot somatostatin analogues are well accepted as either adjuvant or primary therapy for acromegaly, and their long dosage intervals facilitate adherence to treatment. Our objective was to evaluate whether lanreotide Autogel 120 mg, every 4-8 weeks, was as effective in controlling acromegaly as lanreotide microparticles 30 mg, every 1-2 weeks. PATIENTS DESIGN AND MEASUREMENTS: Patients who had used lanreotide microparticles 30 mg, >or= 2 months prestudy, and had responded to treatment were recruited to this open, prospective, multicentre phase III trial. Three to five injections of lanreotide Autogel 120 mg were administered. Lanreotide Autogel 120 mg was injected every 4, 6 or 8 weeks in patients previously receiving lanreotide microparticles every 7, 10 or 14 days, respectively. GH and insulin-like growth factor (IGF)-1 levels were assessed one dosing interval after the final injections.

RESULTS

Ninety-eight patients were enrolled and 93 completed. Steady-state GH concentrations demonstrated similar efficacy between the formulations (upper 95% confidence interval of the quotient, 77.7%). Mean (SE) GH levels were lower with lanreotide Autogel than with lanreotide microparticles (3.8 (0.5) vs 4.3 (0.5) ng/ml; P < 0.001). GH levels < 2.5 ng/ml were observed in 54% and 46% of patients; 40% and 35% having GH < 2.5 ng/ml and normalized IGF-1 with lanreotide Autogel and microparticles, respectively. Symptoms were controlled better with lanreotide Autogel and treatment was well accepted.

CONCLUSIONS

Lanreotide Autogel 120 mg every 4-8 weeks, is at least as effective and as well tolerated in acromegaly as lanreotide microparticles 30 mg injected every 7-14 days.

Normal delivery following an uneventful pregnancy in a Japanese acromegalic patient after discontinuation of octreotide long acting release formulation at an early phase of pregnancy

We report a 35-year-old woman with active acromegaly despite pituitary surgery and irradiation who received continuous octreotide LAR treatment for the control of GH excess until discovery of her pregnancy. The patient delivered a healthy boy following an uneventful pregnancy after discontinuing octreotide LAR as soon as possible at the early phase of pregnancy. Despite a substantial maternal-fetal transfer of octreotide, postnatal development was normal at 3 years of age. In almost all previously described cases, octreotide was discontinued after pregnancy was confirmed. No side-effects of mother or fetus have been reported. Octreotide treatment in pregnancy seems to be feasible and safe. Due to the still-limited number of reported cases treated with octreotide LAR, the potential benefits of octreotide LAR treatment should be weighed carefully against its possible risks.

Controlled release of levonorgestrel from biodegradable poly(D,L-lactide-co-glycolide) microspheres: in vitro and in vivo studies

Poly(D,L-lactide-co-glycolide) (PLG) biodegradable microspheres containing a contraceptive drug, levonorgestrel (LNG), were prepared using both the solvent evaporation method and a modified solvent extraction-evaporation method. The microspheres prepared with the solvent evaporation process had porous surfaces with low product yields and poor encapsulation efficiencies. On the other hand, the microspheres prepared using the modified solvent extraction-evaporation method were nonporous with encapsulation efficiencies close to 100%. In vitro drug release showed the nonporous microspheres had a lower initial burst and a slightly prolonged duration of release than those porous microspheres. In vivo release kinetics of the low burst microspheres were determined by measuring LNG plasma levels after a single intramuscular injection to female rats. At a LNG dose of 41.1 mg/kg, average plasma LNG levels were 6-10 ng/ml in the first 24 h and subsequently remained above 1 ng/ml until 126 days. The duration above the minimum effective LNG plasma level of 0.2 ng/ml was 168 days. By comparison, a similar dose of LNG microcrystals used as control produced a much higher plasma level of 15-21 ng/ml in the first day followed by a fast and continuous decline of LNG levels with a duration of only about 35 days.

Resistance to somatostatin analogs in acromegaly: an evolving concept?

The aim of acromegaly treatment is to control the disease by suppressing GH hyperactivity and reducing the size or impeding the growth of the pituitary GH secreting mass. Over recent years, many studies have emphasized the role of SS analogs in the treatment of acromegaly. In fact, SS analogs have been demonstrated to be an effective tool not only in the control of GH hypersecretion but also more recently in the control of tumor growth, in a relevant number of acromegalic patients both as primary or adjunctive treatment. In this context, the therapeutic failure of medical treatment with SS analogs needs to be accurately defined particularly when they are used as primary treatment but also when they are given to patients previously operated upon, since other effective therapeutic options are nowadays available. Current definition of resistance to SS analogs is based on their efficacy to control GH and IGF-I. However, due to the emerging significance of the shrinkage effect of SS analogs on pituitary adenomas as well as to the apparent dissociation between this effect and the biochemical effects of treatment with these analogs, an evolution in the concept of SS resistance is likely to be occurring. In this review, we will discuss the biological basis of the discordance between biochemical and volumetric effects of SS analogs, and we will address the intriguing clinical and therapeutic aspects related to a possible redefinition of the resistance to SS analogs.

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

The aim of the present multicentric, open-label, non-comparative study was to evaluate the role of octreotide long-acting repeatable (LAR) as primary therapy for the treatment of GH-secreting pituitary macroadenomas. The patients received octreotide LAR 20 mg every 4 weeks for 12 weeks; afterwards the dose was confirmed or adjusted at 30 mg every 4 weeks, for the remaining 12 weeks, for responder or non-responder patients, respectively. Responder patients continued the study until 48 weeks. Twenty-one naive active acromegalic patients were enrolled. In all patients, GH profile, IGF-I levels and magnetic resonance imaging (MRI) were evaluated at baseline and during treatment. The ability of octreotide LAR to decrease mean GH < 2.5 microg/I and/or normalize IGF-I levels, adjusted for age and gender, was defined respectively as total or partial success. Total success was achieved in 5/21 (23.8%), 6/20 (30%) and 4/14 (28.6%) patients after 12, 24 and 48 weeks; partial success in 7/21 (33.3%), 9/20 (45%) and 9/14 (64%) patients at 12, 24 and 48 weeks according to GH levels, while according to IGF-I levels in 7/21 (33.3%), 7/20 (35%) and 5/14 (35.7%) patients at 12, 24 and 48 week. Tumor size was notably decreased after treatment with octreotide LAR: in 16 macroadenoma patients completing the study, the tumor sizes were 1609 +/- 1288, 818 +/- 616 (49.1 +/- 23.7%) and 688 +/- 567 mm3 (54.6 +/- 24.4%) at baseline, 24 and 48 weeks. This study shows that octreotide LAR is effective in suppressing GH/IGF-I secretion and inducing tumor shrinkage in GH-secreting macroadenomas in a 48-week treatment. Octreotide LAR could be used as primary therapy in patients harbouring large pituitary tumors, who are less likely to be cured by neurosurgery.

Efficacy of depot long-acting release octreotide therapy in severe dumping syndrome

BACKGROUND

Dumping syndrome is a serious complication occurring in 10% of patients after gastric surgery. Dumping symptoms are effectively reduced by subcutaneous application of the somatostatin analogue octreotide, but side-effects limit its use.

AIM

To evaluate the efficacy of depot long-acting release octreotide (Sandostatin-LAR) vs. octreotide subcutaneous on dumping symptoms, quality of life and side-effects.

METHODS

Twelve patients (five females, age 58 +/- 3 years) with severe dumping symptoms, requiring daily use of octreotide subcutaneous, were included in an open study and changed from octreotide subcutaneous after a 2 weeks washout to Sandostatin-LAR 10 mg i.m., every 4 weeks for 6 months. Symptoms (diary), body weight, fat excretion, food intake and Gastrointestinal Specific Quality of Life Index were evaluated.

RESULTS

Gastrointestinal Specific Quality of Life Index increased significantly (P < 0.05) during Sandostatin-LAR treatment (88 +/- 4) compared with octreotide (74 +/- 4) and washout (75 +/- 6). During Sandostatin-LAR treatment, abdominal symptom score was lower compared with octreotide and washout, but not significantly. During Sandostatin-LAR treatment, body weight increased (66 +/- 4 to 70 +/- 3 kg; P = 0.19).

CONCLUSIONS

Sandostatin-LAR is at least as effective as octreotide subcutaneous in suppressing symptoms in patients with severe dumping syndrome and is more effective than octreotide subcutaneous in increasing body weight and quality of life.

Solvent exchange method: a novel microencapsulation technique using dual microdispensers

PURPOSE

A new microencapsulation method called the "solvent exchange method" was developed using a dual microdispenser system. The objective of this research is to demonstrate the new method and understand how the microcapsule size is controlled by different instrumental parameters.

METHOD

The solvent exchange method was carried out using a dual microdispenser system consisting of two ink-jet nozzles. Reservoir-type microcapsules were generated by collision of microdrops of an aqueous and a polymer solution and subsequent formation of polymer films at the interface between the two solutions. The prepared microcapsules were characterized by microscopic methods.

RESULTS

The ink-jet nozzles produced drops of different sizes with high accuracy according to orifice size of a nozzle, flow rate of the jetted solutions, and forcing frequency of the piezoelectric transducers. In an individual microcapsule, an aqueous core was surrounded by a thin polymer membrane; thus, the size of the collected microcapsules was equivalent to that of single drops.

CONCLUSIONS

The solvent exchange method based on a dual microdispenser system produces reservoir-type microcapsules in a homogeneous and predictable manner. Given the unique geometry of the microcapsules and mildness of the encapsulation process, this method is expected to provide a useful alternative to existing techniques in protein microencapsulation.

The 'bio-assay' quality of life might be a better marker of disease activity in acromegalic patients than serum total IGF-I concentrations

OBJECTIVES

To investigate the quality of life (QoL) in acromegalic patients in relation to biochemical parameters.

DESIGN AND METHODS

Single-center, open label study in 14 acromegalic patients (eight woman and six men, age 33-77 years), with normal serum IGF-I levels during long-term treatment with monthly injections of 20 mg of long-acting octreotide. We investigated which biochemical parameter might reflect optimal QoL, using the SF-36 questionnaire.

RESULTS

We observed that six patients had a low QoL score at baseline in the same range as observed in cancer patients. The other eight patients had a normal QoL. GH, IGF-I nor free IGF-I could discriminate these two subgroups at baseline. After skipping one monthly injection, all six subjects with the low QoL escaped in their free IGF-I concentrations. Also total IGF-I concentrations escaped in four of these six. In the subjects with normal QoL, free IGF-I levels remained normal in all, while total IGF-I levels only escaped in one.

CONCLUSIONS

This study tells us that the currently used biochemical criteria for disease control in acromegaly might be sufficient in assessing long-term mortality and morbidity, but they are insufficient in addressing the most important parameter from the patient's perspective--QoL.

Calcium Dobesilate in the Treatment of Diabetic Retinopathy

The incidence of diabetic retinopathy is still increasing in developed countries. Tight glycemic control and laser therapy reduce vision loss and blindness, but do not reverse existing ocular damage and only slow the progression of the disease. New pharmacologic agents that are currently under development and are specifically directed against clearly defined biochemical targets (i.e. aldose reductase inhibitors and protein kinase C-beta inhibitors) have failed to demonstrate significant efficacy in the treatment of diabetic retinopathy in clinical trials. In contrast, calcium dobesilate (2,5-dihydroxybenzenesulfonate), which was discovered more than 40 years ago and is registered for the treatment of diabetic retinopathy in more than 20 countries remains, to our knowledge, the only angioprotective agent that reduces the progression of this disease. An overall review of published studies involving calcium dobesilate (CLS 2210) depicts a rather 'non-specific' compound acting moderately, but significantly, on the various and complex disorders that contribute to diabetic retinopathy. Recent studies have shown that calcium dobesilate is a potent antioxidant, particularly against the highly damaging hydroxyl radical. In addition, it improves diabetic endothelial dysfunction, reduces apoptosis, and slows vascular cell proliferation.