Efficacy and safety of prolonged-release lanreotide in patients with gastrointestinal neuroendocrine tumors and hormone-related symptoms

Is the new WHO classification of neuroendocrine tumours useful for selecting an appropriate treatment?

BACKGROUND

Neuroendocrine tumours (NETs) are a rare and heterogeneous group of neoplasms. The most recent WHO classification provides clinical tools and indications to make the diagnosis and to suggest the correct treatment in different subgroups of patients. The aim of this trial was to apply the new classification criteria in clinical practice and, accordingly, to choose the most appropriate treatment.

PATIENTS AND METHODS

Thirty-one evaluable patients, not previously treated, classified as advanced well differentiated NETs according to the new classification, were given long-acting release octreotide 30 mg every 28 days until evidence of disease progression. The treatment activity was evaluated according to objective, biochemical and symptomatic responses. Safety and tolerability were also assessed.

RESULTS

Two partial objective tumour responses were obtained (6%), stabilization occurred in 16 patients (52%) and 95% of patients had a disease stabilisation lasting > or =6 months. However, eight patients showed rapid disease progression within 6 months of therapy and six patients after 6 months. Biochemical responses, evaluated by changes in serum chromogranine A levels were reported in 20/24 patients (83%). Symptomatic responses were observed in 6/14 patients (43%): a complete syndrome remission in one patient, partial syndrome remission in five patients, no change in four patients and progressive disease in four patients. The median overall survival was not reached, and the median time to disease progression was 18 months (range 1-49 months). The treatment was well tolerated, no severe adverse events were observed and no patient withdrew from the study because of adverse events.

CONCLUSIONS

The WHO classification enables identification of low-grade NET patients who may be suitable for hormonal treatment. Octreotide LAR was seen to be effective in controlling the disease and was well tolerated. However, eight patients failed to respond to the treatment, despite histological evidence of a well differentiated tumour according to the new classification. This suggests that further histological examination should be carried out, especially in patients with visceral metastases and a short disease-free interval.

Metastatic carcinoid tumors: a clinical review

Carcinoid tumors are neuroendocrine tumors derived from enterochromaffin cells, which are widely distributed in the body. They can originate from any location in the body, but they are traditionally described as originating from the foregut, midgut, and hindgut. Although the overall incidence of carcinoid tumors appears to have increased in the past decades, the prognosis for patients with metastatic carcinoid tumors has improved during the last decade. Due to longer survival times, complications, such as carcinoid heart disease, and new metastatic patterns, like skin and bone metastases, may become more important features of carcinoid disease. Therapy focused on these complications should be part of the management. Combining new diagnostic and treatment modalities in metastatic carcinoid patients may result in better quality of life and longer survival times. The increasing number of therapeutic options and diagnostic procedures requires a multidisciplinary approach, with decisions made in multidisciplinary meetings focused on "tailor-made" therapy based on patients' specific conditions. Because carcinoid tumors are uncommon, effort should be made to treat these patients in specialized centers and for these centers to join together in multicenter studies.

Current status of gastrointestinal carcinoids

Gastrointestinal (GI) carcinoids are ill-understood, enigmatic malignancies, which, although slow growing compared with adenocarcinomas, can behave aggressively. Carcinoids are classified based on organ site and cell of origin and occur most frequently in the GI (67%) where they are most common in small intestine (25%), appendix (12%), and rectum (14%). Local manifestations--mass, bleeding, obstruction, or perforation--reflect invasion or tumor-induced fibrosis and often result in incidental detection at emergency surgery. Symptoms are protean (flushing, sweating, diarrhea, bronchospasm), usually misdiagnosed, and reflect secretion of diverse amines and peptides. Biochemical diagnosis is established by elevation of plasma chromogranin A (CgA), serotonin, or urinary 5-hydroxyindoleacetic acid (5-HIAA), while topographic localization is by Octreoscan, computerized axial tomography (CAT) scan, or endoscopy/ultrasound. Histological identification is confirmed by CgA and synaptophysin immunohistochemistry. Primary therapy is surgical excision to avert local manifestations and decrease hormone secretion. Hepatic metastases may be amenable to cytoreduction, radiofrequency ablation, embolization alone, or with cytotoxics. Hepatic transplantation may rarely be beneficial. Chemotherapy and radiotherapy have minimal efficacy and substantially decrease quality of life. Intravenously administered receptor-targeted radiolabeled somatostatin analogs are of use in disseminated disease. Local endoscopic excision for gastric (type I and II) and rectal carcinoids may be adequate. Somatostatin analogues provide the most effective symptomatic therapy, although interferon has some utility. Overall 5-year survival for carcinoids of the appendix is 98%, gastric (types I/II) is 81%, rectum is 87%, small intestinal is 60%, colonic carcinoids is 62%, and gastric type III/IV is 33%.

Enteroendocrine tumors other than carcinoid: a review of clinically significant advances

Only relatively recently has there been an increased clinical recognition and characterization of the heterogeneous group of rare gastroenteropancreatic neuroendocrine neoplasms. Most have endocrine function and exhibit varying degrees of malignancy. This review summarizes the derivation of these tumors and the advances in their diagnosis and treatment over the past decade and a half. They are varied in their biological behavior and clinical courses and, depending on their cell type, can produce different hormones causing distinct clinical endocrine syndromes (insulinoma [hypoglycemia], gastrinoma [Zollinger-Ellison syndrome (ZES)], vasoactive intestinal peptideoma [VIPoma], watery diarrhea, hypokalemia-achlorhydria [WDHA], glucagonoma [glucagonoma syndrome], and so forth). In addition to surgery for cure or palliation (by excision and a variety of other cytoreductive techniques), they each are treated with anti-hormonal agents or drugs targeted to each tumor's specific product or its effects. The majority have benefited from the gut hormone-inhibiting action of somatostatin analogs. Because of their usual slow rate of growth it is recommended that, even when they are advanced and incurable, unlike in patients with common and more malignant cancers, patients with neuroendocrine tumors often can be palliated and appear to survive longer when managed with an active approach using sequential multimodality treatment. Advances in these various therapies are reviewed and the beneficial emergence of global self-help patient support groups is noted.

Somatostatin analogues in the treatment of gastroenteropancreatic neuroendocrine tumors

Gastroenteropancreatic neuroendocrine tumors constitute a heterogeneous group of neoplasms that are often associated with typical symptoms due to excessive and uncontrolled release of diverse hormones. Because these tumors are usually slow growing, surgery is the cornerstone of treatment. However, these rare tumors can present with rapid progression that requires aggressive systemic therapy or diffuse metastatic disease not amenable to surgical palliation. For most patients, medical approaches are necessary at some point in the course of their disease, especially since most tumors are at an advanced stage at the time of diagnosis. Most gastroenteropancreatic neuroendocrine tumors express high levels of somatostatin receptors, which are bound by somatostatin or its synthetic analogues. These agents, alone or combined with other therapies, such as Interferon or radioisotopes, are therefore used frequently to control hormone-related symptoms and, for some patients, the growth of the disease Itself. This article reviews the evidence for the use of somatostatin analogues in the treatment of gastroenteropancreatic neuroendocrine tumors based on a MEDLINE search of literature published from January 1970 to July 2003.

Guidelines for the management of gastroenteropancreatic neuroendocrine tumours (including bronchopulmonary and thymic neoplasms). Part II-specific NE tumour types

Part II of the guidelines contains a description of epidemiology, histopathology, clinical presentation, diagnostic procedure, treatment, and survival for each type of neuroendocrine tumour. We are not only including gastroenteropancreatic tumours but also bronchopulmonary and thymic neuroendocrine tumours. These guidelines essentially cover basic knowledge in the diagnosis and management of the different forms of neuroendocrine tumour. We have, however, tried to give more updated information about the epidemiology and histopathology, which is essential for the clinical management of these tumours.

The diagnosis and medical management of advanced neuroendocrine tumors

Neuroendocrine tumors (NETs) constitute a heterogeneous group of neoplasms that originate from endocrine glands such as the pituitary, the parathyroids, and the (neuroendocrine) adrenal, as well as endocrine islets within glandular tissue (thyroid or pancreatic) and cells dispersed between exocrine cells, such as endocrine cells of the digestive (gastroenteropancreatic) and respiratory tracts. Conventionally, NETs may present with a wide variety of functional or nonfunctional endocrine syndromes and may be familial and have other associated tumors. Assessment of specific or general tumor markers offers high sensitivity in establishing the diagnosis and can also have prognostic significance. Imaging modalities include endoscopic ultrasonography, computed tomography and magnetic resonance imaging, and particularly, scintigraphy with somatostatin analogs and metaiodobenzylguanidine. Successful treatment of disseminated NETs requires a multimodal approach; radical tumor surgery may be curative but is rarely possible. Well-differentiated and slow-growing gastroenteropancreatic tumors should be treated with somatostatin analogs or alpha-interferon, with chemotherapy being reserved for poorly differentiated and progressive tumors. Therapy with radionuclides may be used for tumors exhibiting uptake to a diagnostic scan, either after surgery to eradicate microscopic residual disease or later if conventional treatment or biotherapy fails. Maintenance of the quality of life should be a priority, particularly because patients with disseminated disease may experience prolonged survival.

Pharmacokinetics of a new Autogel formulation of the somatostatin analogue lanreotide after a single subcutaneous dose in healthy volunteers

The pharmacokinetics/tolerability of lanreotide Autogel have been evaluated. Healthy volunteers (n = 24) first received immediate-release lanreotide as a single subcutaneous (s.c.) injection. After two days, 40 or 60 mg lanreotide Autogel was injected subcutaneously. Blood was sampled at various intervals for 56 days. Systemic/local adverse events and changes in biological profile/vital signs were recorded. Lanreotide Autogel produced a prolonged-release pharmacokinetic profile: mean area under the serum concentration-time curve from time 0 to infinity (AUC) was 53.73 +/- 8.99 and 79.48 +/- 13.06 ng mL(-1) day for 40 and 60 mg, respectively, mean peak serum concentration (C(max)) was 4.38 +/- 2.91 and 5.71 +/- 3.52 ng mL(-1), respectively, median time to reach C (minimum-maximum) was 0.50 (0.083-18.0) and 0.38 (0.083-9.01) days, respectively, mean apparent elimination half-life was 21.63 +/- 9.42 and 22.01 +/- 9.87 days, respectively, and relative bioavailability was 0.93 +/- 0.12 and 0.82 +/- 0.15, respectively. Thus, lanreotide Autogel exhibited linear pharmacokinetics for the doses studied. Pharmacokinetic profiles were similar in both genders, apart from statistically significant differences in C(max) and C(max)/AUC. The Autogel formulation of lanreotide was well tolerated, with systemic adverse events being mild/moderate. Erythema and a painless subcutaneous induration were the most common local adverse events. Lanreotide Autogel provided a prolonged dosing interval and good tolerability for treating acromegaly and carcinoid syndrome.

Basis for treatment of functioning neuroendocrine tumours

A general characteristic of GEP endocrine tumours is that vast majority produce and secrete a multitude of peptide hormones and amines. The rarity of these types of tumours, their possible episodic expression and the variable clinical symptoms, are the reasons why patients are often diagnosed late in the advanced stages of the disease. For these reasons, the patients with advanced metastatic disease should be treated aggressively with medical and surgical therapies aimed at reducing both symptoms and complications through strategies that reduce tumour bulk and block hormonal effects. The medical treatment of functioning endocrine tumours of the gastrointestinal tract must be based on the growth properties of the tumour and includes chemotherapy, somatostatin analogs, alpha-interferon alone and associated with somatostatin analogs, chemoembolization and radiolabelled somatostatin analogs. Even if chemotherapy has been basis of therapy for these types of tumours for a long time, it is currently reserved for progressive disease and anaplastic tumours. Biotherapy, with interferon and somatostatin analogs has been demonstrated to have a significant antitumor effect and causes an improvement of symptoms in patients with functioning neuroendocrine tumours. Furthermore, these drugs produce a notable improvement in the quality of life. Radioactive targeting therapy is the most promising new treatment modality for patients who have SST receptor positive tumours.

Unlabelled somatostatin analogues in treatment of digestive endocrine tumours

Somatostatin analogues are considered first-line therapy in patients with digestive endocrine tumours. Indeed, several studies have investigated their efficacy in the control of specific symptoms and in the decrease of tumour markers. However, randomised controlled trials are needed in order to better define their role in non functioning tumours and their effect on tumour growth, which have seldom been assessed. Several new drugs have been developed over the last few years such as, for example, new long-acting formulations, universal analogues binding to all five somatostatin receptors subtypes, and cytotoxic analogues, all of which offer a promising therapeutic tool in the near future, even if further studies are needed to determine their efficacy and safety in man.

Guidelines for the management of gastroenteropancreatic neuroendocrine tumours (including bronchopulmonary and thymic neoplasms). Part I-general overview

The incidence of neuroendocrine tumours of the gastroenteropancreatic system seems to have increased during the past decade. New diagnostic and therapeutic procedures have aroused the interest of physicians, though most see very few cases of such diseases. A group of members of the Nordic Neuroendocrine Tumour Group decided to compile some guidelines to facilitate the diagnosis and treatment of patients with these tumours. Part I of these guidelines discusses the principles of histopathology, biochemical and radiological diagnosis as well as therapeutic options.

Rapid and sustained relief from the symptoms of carcinoid syndrome: results from an open 6-month study of the 28-day prolonged-release formulation of lanreotide

This 6-month, open, non-controlled, multicenter, dose-titration study evaluated the efficacy and safety of 28-day prolonged-release (PR) lanreotide in the treatment of carcinoid syndrome. Eligible patients had a carcinoid tumor with > or =3 stools/day and/or > or =1 moderate/severe flushing episodes/day. Six treatments of 28-day PR lanreotide were administered by deep subcutaneous injection. The dose for the first two injections was 90 mg. Subsequent doses could be titrated (60, 90, 120 mg) according to symptom response. Seventy-one patients were treated. Flushing decreased from a mean of 3.0 at baseline to 2.3 on day 1, and 2.0 on day 2, with a daily mean of 2.1 for the first week post-treatment (p < 0.05). Diarrhea decreased from a mean of 5.0 at baseline to 4.3 on day 1 (p < 0.05), and 4.5 on day 2, with a daily mean of 4.4 for the first week post-treatment (p < 0.001). Symptom frequency decreased further after the second and third injections, and reached a plateau after the fourth injection. By month 6, flushing and diarrhea had significantly decreased from baseline by a mean of 1.3 and 1.1 episodes/day, respectively (both p < or = 0.001); 65% of patients with flushing as the target symptom and 18% of diarrhea-target patients achieved > or =50% reduction from baseline. Median urinary 5-hydroxyindoleacetic acid and chromogranin A levels decreased by 24 and 38%, respectively. Treatment was well tolerated. 28-day PR lanreotide was effective in reducing the symptoms and biochemical markers associated with carcinoid syndrome.

Functional activity of the multiligand analog SOM230 at human recombinant somatostatin receptor subtypes supports its usefulness in neuroendocrine tumors

Functional gastroenteropancreatic tumors express all 5 somatostatin receptor subtypes (sst) in different quantities. Octreotide and lanreotide treat patients with these tumors by binding preferentially to sst2 and, to a lesser extent, to sst3 and sst5 receptors, thereby controlling prominent symptoms caused by hormone hypersecretion (diarrhea and flushing). Although symptoms initially improve in most patients, a loss of response occurs in about 50% during continuous treatment. The functional activity at sst receptors of SOM230, a new multiligand somatostatin analog, has been described and compared with that of somatostatin (SRIF-14) and octreotide. These data show that SOM230 is a full agonist with nanomolar potency at sst(1,2,3) and sst5 receptors. The multiligand activity profile of SOM230, together with its nondesensitizing inhibitory effect on growth hormone and insulin-like growth factor-I secretion in rats, may underlie its successful use in clinical trials and its potential for use in refractory patients with carcinoid tumors.

Somatostatin analog therapy in treatment of gastrointestinal disorders and tumors

Long-acting octapeptide somatostatin analogs can effectively control symptoms resulting from excessive hormone release in patients with endocrine tumors of the gastrointestinal tract, provided that these tumors and metastases show a high expression of the somatostatin receptor subtype 2. The presence of this receptor subtype on these tumors can be demonstrated by in vitro studies, but also in vivo using 111In-pentetreotide scintigraphy. In a few studies, significant antiproliferative effects of these drugs on these tumors have also been demonstrated. The effectiveness of octapeptide somatostatin analogs in the management of chemotherapy- related and AIDS-related diarrhea and in reducing postoperative complications of pancreatic surgery have also been demonstrated. These drugs have been used to decrease the output of enterocutaneous pancreatic fistulas and are prophylactically used to prevent the development of these fistulas. Octapeptide somatostatin analog therapy is widely accepted for the initial management of acute variceal bleeding in cirrhotic patients. These drugs are currently also being evaluated for the treatment of advanced hepatocellular carcinoma and malignant intestinal obstruction. Radiotherapy with octapeptide somatostatin analogs coupled to radionuclides such as indium-111, yttrium-90, and lutetium- 177 is currently being studied in phase I-III trials.

The pathophysiological consequences of somatostatin receptor internalization and resistance

Somatostatin receptors expressed on tumor cells form the rationale for somatostatin analog treatment of patients with somatostatin receptor-positive neuroendocrine tumors. Nevertheless, although somatostatin analogs effectively control hormonal hypersecretion by GH-secreting pituitary adenomas, islet cell tumors, and carcinoid tumors, significant differences are observed among patients with respect to the efficacy of treatment. This may be related to a differential expression of somatostatin receptor subtypes among tumors. In addition, the property of somatostatin receptor subtypes to undergo agonist-induced internalization has important consequences for visualizing, as well as for therapy, of receptor-positive tumors using radioisotope- or chemotherapeutic-compound-coupled somatostatin analogs. This review covers the pathophysiological role of somatostatin receptor subtypes in determining the efficacy of treatment of patients with somatostatin receptor-positive tumors using somatostatin analogs, as well as the preclinical and clinical consequences of agonist-induced receptor internalization for somatostatin receptor-targeted radio- and chemotherapy. Herein, the development and potential role of novel somatostatin analogs is discussed.

Use of octreotide and lanreotide in the treatment of symptomatic non-resectable carcinoid tumours

BACKGROUND

Carcinoid tumours are rare neoplasms that secrete hormones and biogenic amines, most commonly serotonin. Octreotide and long acting lanreotide are found to be useful in the management of carcinoid syndrome by its interaction with somatostatin receptor, found on the carcinoid tumour. The aim of this study is to look at the efficacy of octreotide and long acting lanreotide in the treatment of symptomatic non-resectable carcinoid tumours.

METHOD

The effects of octreotide and long-acting lanreotide were studied in 10 patients with symptomatic non-resectable carcinoid tumours.

RESULTS

Symptom improvement occurred in nine of 10 patients. Three patients responded only to octreotide, three patients responded to both octreotide and long-acting lanreotide and three patients only responded to long-acting lanreotide. Slight reductions in 24-h urine 5-hydroxyindoleacetic acid levels occurred in three of six patients but no patients were found to have objective tumour regression on computed tomography scan.

CONCLUSIONS

Octreotide and long-acting lanreotide are useful palliative treatments for the control of symptoms in patients with non-resectable carcinoid tumours but there is no evidence of tumour stasis.

Somatostatin analogues in the treatment of endocrine tumors of the gastrointestinal tract

Somatostatin and its long-acting analogues have been introduced for the treatment of endocrine tumours of the gastrointestinal tract as they have been shown to effectively control symptoms resulting from excessive hormone release in patients with carcinoid, Verner-Morrison and glucagonoma syndromes. This beneficial effect is due to the presence of somatostatin receptors in high densities on the majority of endocrine tumours. The symptomatic effect is less pronounced in insulinomas, since 30 - 50% of these tumours lack or express only a few somatostatin receptors. With respect to symptomatic control, somatostatin receptor subtypes 2 and 5 are the most important and the currently available long-acting analogues octreotide and lanreotide bind preferentially to these receptor subtypes. Long-term studies have shown that somatostatin analogues are safe and that the most important adverse advent is the development of gallstones. The antiproliferative potency of somatostatin and its analogues in vitro and in experimental tumour models prompted a number of studies in patients with metastatic endocrine tumours that are generally unresponsive to conventional chemotherapeutic protocols. Stabilisation of tumour growth lasting for months to a few years was the most favourable result, occurring in 30 - 70% of patients. However, definite proof of antiproliferative potency in man is still pending since placebo-controlled studies are not available. Radioligand therapy based on 111Indium, 90Yttrium and 177Lutetium coupled to somatostatin analogues via bifunctional chelators is currently under investigation with promising data concerning long-lasting control of symptoms and tumour growth from Phase I trials.

The clinical role of somatostatin analogues as antineoplastic agents: much ado about nothing?

BACKGROUND

Somatostatin (SST) analogues represent a novel approach for the treatment of certain cancers. The objective of this article is to summarise the current knowledge on SST analogues in the treatment of cancer patients.

METHODS

Computerised (Medline) and manual searches were performed to identify publications on clinical trials published in the English-speaking literature between 1966 and 2000. Information abstracted included patients' pre-treatment status, histology, SST receptor (SSTR) evaluation, type of SST analogue, application schedule and dose, duration of treatment, side-effects, response criteria applied (i.e. WHO response criteria, biochemical criteria or symptomatic investigations) and survival.

RESULTS

Our search disclosed 22 case reports, five phase 1 and 47 phase II trials, and eight randomised clinical trials using SST analogues (octreotide, lanreotide and vapreotide) as antineoplastic agents. With regard to the phase II trials, conflicting results have been demonstrated in almost all tumour entities investigated. The few randomised studies published so far have shown an impact on survival in patients with hepatocellular cancer, while the effect attributed to treatment in patients with gastrointestinal adenocarcinomas might well have been due to an exceptionally short survival in the control group. There appears to be evidence that SST analogues are able to enhance the therapeutic effects of hormonal intervention in patients with breast cancer, prostate cancer and probably pancreatic cancer. Interpretation of the findings, however, is complicated by the fact that patients were heavily pre-treated in some studies and response criteria have not been uniformly applied. In addition, most studies have not been designed to distinguish between receptor-mediated (direct) and indirect effects of SST analogues in tumour patients.

CONCLUSIONS

According to the results obtained so far, there can be no doubt about the wide therapeutic index and the high efficacy of SST analogues in the symptomatic management of neuroendocrine tumours. Apart from these indications, the data do not justify recommendation of SST analogues as antineoplastic agents outside of clinical trials, as the optimal dose and schedule of application for antineoplastic activity has not been defined for currently used agents. Carefully designed clinical trials including investigation of SSTR status before treatment, evaluation of an indirect mechanism of SST analogues, and assessment of optimal combination of hormone therapy and chemotherapy with SST analogues are clearly needed in the near future.

Chemotherapy and biotherapy in the treatment of neuroendocrine tumours

The medical treatment of neuroendocrine GEP tumours must be based on the growth properties of the tumour. Medical treatment includes chemotherapy, somatostatin analogues and alpha interferons. Chemotherapy has been particularly active in patients with high proliferating neuroendocrine tumours such as endocrine pancreatic tumours and lung carcinoids. Streptozotocin-based combinations including 5-flourouracil and doxorubicin have generated partial remissions in 40%-60% of the patients giving a median survival of about two years in patients with advanced disease. Cisplatinum plus etoposide have demonstrated significant antitumour effects in anaplastic endocrine pancreatic tumours and lung carcinoids. However, in low proliferating tumours such as classical midgut carcinoids the response rates with the same combinations of cytotoxic agents have only generated short lasting responses in less than 10% of patients. In these patients, biological treatment has been of benefit. Alpha interferon at doses of 3-9 million units three to seven times per week subcutaneously, has given biochemical response rates of 50% and significant tumour reduction in about 15% of patients with long duration, up to three years. Somatostatin analogues have been widely used in the treatment of neuroendocrine gut and pancreatic tumours. The currently available somatostatin analogues particularly bind somatostatin receptor 2 and 5 and with low affinity also receptor subtype 3. Octreotide is registered in most countries for the treatment of patients with carcinoid syndrome and also VIP and glucagon producing tumours. Regular octreotide at standard doses of 100-300 microg/day gives symptomatic responses in a medium of 60% of patients and biochemical responses in up to 70% of patients. Significant tumour responses are rare, less than 5%. Long-acting formulations of somatostatin analogues have been of significant benefit for the patients with similar response rates as for regular formulations. The quality of life has been significantly improved by using the long-acting formulations.

The clinical management of neuroendocrine tumors with long-acting repeatable (LAR) octreotide: comparison with standard subcutaneous octreotide therapy

Neuroendocrine tumors are rare, occurring in less than 1% of the population. They are divided clinically into functionally active or non-active tumors. Functionally active tumors produce a variety of substances (mainly peptides or serotonin) that are responsible for symptoms and sometimes can lead to the death of the patient independently from tumor proliferation. The most important compounds that can control symptoms in these patients are somatostatin analogs. Native somatostatin is not suitable for long-term clinical application due to its short half-life. Therefore, synthetic drugs were developed with improved pharmacokinetic characteristics. The best-characterized analog, octreotide, has been successfully applied to patients with functioning tumors. Octreotide can ameliorate symptoms in 30%-70% of the patients, mainly through a direct inhibitory effect on hormone production from the tumors. There is little or no effect on tumor growth during octreotide therapy; clinical responses were recorded in only 10%-30% of the patients. Recently, significant improvement in the management of the disease has been demonstrated with long-acting repeatable (LAR) octreotide. This new formulation requires only one monthly intramuscolar injection, and shows better acceptability and patient compliance to therapy. Data available to date show superimposable results of both standard octreotide and LAR octreotide in controlling symptoms, lowering hormone and tumor marker levels, and in reducing tumor growth. The availability of long-acting molecules have permitted the exploration of high-dose therapy in increasing tumor shrinkage and prolonging survival. Although there is a clear dose-response trend, the published data are not conclusive and further investigations are needed. The possible lack of cross-resistance between LAR octreotide and a different analog, Lanreotide, is a very stimulating finding and this might lead to the development of new therapeutical strategies in the management of neuroendocrine tumors.

Somatostatin analogs and prednisone in advanced refractory thymic tumors

BACKGROUND

Therapeutic options to cure advanced, recurrent, and metastatic thymic tumors are limited. Evidence of a high uptake of indium-labeled octreotide ((111)In-DTPA-D-Phe(1)-octreotide) in thymic tumors and the curative application of somatostatin analogs and prednisone in one patient with thymoma and pure red cell aplasia led the authors to start a Phase II study.

METHODS

Sixteen patients with advanced thymic tumors, unresponsive to conventional chemotherapeutic regimens, were enrolled in the study. The schedule includes administration of somatostatin analog octreotide (1.5 mg/day subcutaneously) associated with prednisone (0.6 mg/kg/day orally for 3 months, 0.2 mg/kg/day orally during follow-up). In 8 cases, octreotide was replaced by the long-acting analog lanreotide (30 mg/every 14 days intramuscolarly). Treatment was prolonged until progression of disease was documented. Overall response rate, survival, progression free survival, and toxicity were evaluated.

RESULTS

The overall response rate among 16 evaluable patients was 37%. One patient (6%) had a complete response, 5 (31%) had a partial response, 6 obtained a stabilization of disease, and 4 progressed during the treatment. After a median follow-up of 43 months, the median survival was 15 months, and median time to progression was 14 months. Treatment was generally well tolerated with acceptable toxicity: cholelithiasis (1 patient), Grade 2 cushingoid appearance (3 patients), Grade 1 diarrhea (5 patients), Grade 2 hyperglycemia (3 patients).

CONCLUSIONS

Treatment with somatostatin analogs and prednisone has shown efficacy in patients with recurrent and metastatic malignant thymic tumors refractory to standard therapeutic options. The results obtained are very satisfactory given the lack of effective alternative treatments. Such therapy is not burdened by the same toxicity of chemotherapy; thus, it can be administered to heavily pretreated patients. Somatostatin analogs and prednisone are well tolerated, and the long-acting analog lanreotide, which requires fewer injections, improves patients' compliance.

Somatuline Autogel: an extended release lanreotide formulation

Somatuline Autogel provides effective control of growth hormone levels and is at least as effective as intramuscular Somatuline LA. Somatuline Autogel has a first order kinetic profile providing at least 28 days' efficacy with reduced burst release and a more consistent drug release over the dose period. The product is presented in a pre-filled syringe and is given deep subcutaneously.

Diagnostic, surgical and medical aspect of the midgut carcinoids

This review covers the incidence, prognosis, diagnosis and treatment of midgut carcinoids with emphasis on the surgical and peri-operative aspects. Midgut carcinoids are rare neuro-endocrine tumours which become manifest once they have metastasized to the liver. Treatment of metastatic disease may include radical resection but is usually palliative. The tumour grows relatively slow. Besides the biochemical effects resulting in the carcinoid syndrome, patients may suffer from mechanical mass effects of the tumour. Medical treatment can alleviate the biochemical effects of the tumour, but has a limited effect on tumour growth. The introduction of octreotide was a milestone in palliation of these symptoms and has led to more aggressive treatment protocols. Treatment aimed at cytoreduction of hepatic metastasis and diminished secretion of bioactive amines may achieve good palliation. Cytoreduction may be performed by means of surgery, hepatic arterial ligation, (chemo)embolization, cryosurgery, radio-frequency ablation, internal radiation or even liver transplantation. The role of these options will be discussed in this review.

Prospective study of the antitumor efficacy of long-term octreotide treatment in patients with progressive metastatic gastrinoma

BACKGROUND

Malignant pancreatic endocrine tumors (PETs) have a poor prognosis and existing antitumor treatments are unsatisfactory. Recent studies have shown somatostatin analogues to have antitumor growth effects in patients with malignant PETs; however, to the authors' knowledge, little information exists regarding their efficacy or effect on survival in patients with progressive malignant gastrinoma, the most common symptomatic malignant PET. The purpose of the current study was to study prospectively the efficacy, safety, and effect on survival of long-term treatment with octreotide in consecutive patients with progressive malignant gastrinoma.

METHODS

Fifteen consecutive patients with malignant gastrinoma with progressive hepatic metastases were studied. All patients underwent conventional imaging studies (computed tomography scan, magnetic resonance imaging, ultrasound, and, if needed, selective angiography) and somatostatin receptor scintigraphy prior to treatment and at 3-6-month intervals while receiving treatment. The patients all were treated initially with octreotide, 200 microg every 12 hours, and at last follow-up were being maintained on long-acting release octreotide, 20-30 mg every month. Tumor size and/or number were used to classify patient responses as either no tumor response or tumor response (stabilization or decrease in size). Treatment response was correlated with tumor and clinical characteristics.

RESULTS

Tumors in 8 of the 15 patients studied (53%) responded at 3 months, with 47% (7 of 15 patients) demonstrating tumor stabilization and 6% (1 of 15 patients) demonstrating a decrease in tumor size. The mean duration of response was 25.0+/-6.1 months (range, 5.5-54.1 months). Six of the eight responders were continuing to respond at the time of last follow-up. Tumor response did not correlate with any clinical parameter (e.g., tumor extent, fasting gastrin, or acid secretory rates). However, slow-growing tumors were more likely to respond prior to treatment (86% vs. 0%) (P < 0.0014). During follow-up (range, 4-8 years), 25% of the responders died compared with 71% of the nonresponders, a difference that approached statistical significance (P = 0.10). Two patients (13%) developed serious side effects that required the withdrawal of octreotide.

CONCLUSIONS

Octreotide is an effective antitumor treatment in patients with progressive malignant gastrinoma. In approximately 50% of these patients octreotide has an antigrowth effect; treatment is associated with a low incidence of serious side effects compared with other antitumor treatments commonly used and, in contrast to many studies, the growth response is long-lasting. The results of the current study suggest that octreotide treatment should replace chemotherapy as the standard treatment for these patients, especially those patients with slow-growing tumors. Additional studies involving larger numbers of patients will be needed to determine a convincing effect on survival.

Somatostatin and somatostatin analogues: diagnostic and therapeutic uses

Somatostatin and its octapeptide analogues exert their effects through interaction with somatostatin receptor (sst) subtypes 1 through 5 (sst 1-5 ). Somatostatin binds with high affinity to all sst subtypes, whereas the currently commercially available octapeptide analogues bind only with a high affinity to sst 2 and sst 5. Pituitary tumors, endocrine pancreatic tumors, and carcinoid tumors express multiple sst subtypes, but sst 2 predominance is found in 90% of carcinoids and 80% of endocrine pancreatic tumors. Sst 2 and sst 5 predominance is found in growth hormone-secreting pituitary tumors. In patients harboring sst 2 - or sst 5 -positive neuroendocrine tumors, clinical symptomatology can be controlled by the chronic administration of one of the currently commercially available octapeptide somatostatin analogues. Tumors and metastases that bear sst 2 or sst 5 can be visualized in vivo after injection of radiolabeled octapeptide analogues. Radiolabeled octapeptide analogues can also be used for radiotherapy of sst 2 - and sst 5 -positive advanced or metastatic neuroendocrine tumors.

Gastrinoma

Gastrinoma treatment has evolved considerably in the last 20 years. In particular, the advent of effective acid-reducing pharmacologic agents has changed the primary morbidity of this disease entity from one of acid hypersecretion to one of tumor growth and spread. Thus, while symptoms can be temporized using histamine receptor antagonists, proton pump inhibitors, or somatostatin analogs, cure can be effected only by surgical means. Recent advances in operative techniques and pre- and intra-operative imaging studies, including routine duodenotomy, somatostatin-receptor scintigraphy, and intraoperative ultrasound, have allowed for identification and subsequent resection of more than 95% of gastrinoma tumors. Most experts agree that all sporadic cases of localized gastrinoma should be excised. In addition, debulking of metastatic tumor may improve symptoms and survival when cure cannot be ascertained. There is, however, some controversy as to the surgical approach for gastrinoma found in the setting of multiple endocrine neoplasia, type 1. Because of the usual multiplicity and particular indolence of these tumors, two primary strategies have emerged: aggressive approaches have been advocated in an effort to eradicate all present and potential tumor; and less aggressive, or nonoperative, approaches have been suggested because it is unclear whether intervention offers survival or disease-free benefit in this population. We advocate surgical intervention for patients with gastrinoma and multiple endocrine neoplasia, type 1 when tumors exceed 2.5 cm in size. This tumor size has been associated with a higher likelihood of hepatic metastases, which ultimately affects survival. The role of adjuvant therapies for gastrinoma remains limited.

Islet cell tumors of the pancreas: the medical oncologist's perspective

Islet cell tumors of the pancreas are rare, indolent, neuroendocrine tumors. Approximately 50% of the patients diagnosed with these tumors present with symptoms related to various biologically active hormones that are secreted by these neoplasms. Currently, the only curative treatment for islet cell tumors is complete surgical resection. Management of metastatic disease is conservative. Initial treatment of these tumors includes expectant observation and medical management of symptoms with clinical monitoring and serial CT scans to assess tumor growth. Patients with rapidly progressive disease, with local symptoms caused by tumor bulk, or with uncontrolled symptoms related to hormone secretion require more aggressive medical or surgical intervention. The somatostatin analogue octreotide may help control hormone secretion and stabilize tumor growth. Patients refractory to octreotide with tumor predominantly in the liver are potential candidates for mechanical ablative techniques, such as hepatic arterial embolization. Radiofrequency ablation and cryosurgical techniques may also be useful, although specific data are limited. Surgical resection of metastatic disease may offer palliative relief of symptoms related to hormone secretion in carefully selected patients. Chemotherapy may be used for palliation when ablative techniques have failed or when significant extrahepatic disease is present. Streptozicin-based combinations remain the first line standard, but major objective responses are less common than had been previously thought. Because of the overall modest success of current chemotherapeutic regimens, patients with advanced disease in need of treatment should be encouraged to enroll in clinical trials testing newer antineoplastic agents or newer treatment strategies.

Somatostatin receptor imaging, therapy and new strategies in patients with neuroendocrine tumours

BACKGROUND

Somatostatin receptors have been found on a variety of neuroendocrine tumours, such as carcinoids and paragangliomas, as well as on most pancreatic endocrine and breast tumours. Somatostatin receptor scintigraphy with a radionuclide-labelled somatostatin analogue, [111Indium- diethylenetriaminopenta-acetic acid]octreotide, is a sensitive and specific technique for visualizing in vivo the presence of somatostatin receptors on various tumours.

METHODS

Material was identified from previous review articles, references cited in original papers and a Medline search of the literature. Additional material was obtained from recently published abstracts of meetings.

RESULTS AND CONCLUSION

Somatostatin receptor imaging of neuroendocrine tumours is essential in the diagnostic evaluation of most of these tumours. The expression of somatostatin receptors in vivo not only predicts the outcome of somatostatin analogue treatment but also opens the possibility of new therapeutic strategies. Because better information about spread of the disease can be obtained, more justifiable options for therapy can be proposed.

Recent advances in carcinoid pathogenesis, diagnosis and management

Carcinoid tumors usually present as diagnostic dilemmas due to obscure or nonspecific symptomatology. Advances in molecular biology are allowing the investigation of molecular markers of aggressiveness, better serum tumor markers, as well as the molecular pathogenesis of carcinoid heart disease. Somatostatin receptor scintigraphy (SRS) and whole body positron emission tomography (PET) are providing much improved sensitivity in localization of both primary and metastatic tumors. Long acting depot somatostatin analogues are combining effectiveness and ease of use for medical management of carcinoid syndrome. An additional benefit may be tumor growth suppression.

The antitumoral effect of the long-acting somatostatin analog lanreotide in neuroendocrine tumors

OBJECTIVE

Somatostatin analogs are the first-line drugs for controlling hormone-mediated symptoms of carcinoid tumors. Prospective and retrospective studies have suggested that somatostatin analogs also have antiproliferative activity. The octapeptide lanreotide is available in sustained-release form, obviating the need for daily injections.

METHODS

A total of 46 patients were enrolled in this open, prospective, phase II trial. They received lanreotide 30 mg i.m. every 14 days for 6 months when they had symptomatic carcinoid tumors, and lanreotide 30 mg i.m. every 10 days if they had nonsymptomatic tumors. Nonsymptomatic tumors were progressive before the start of the study. Tumor size was assessed every 3 months by means of computed tomography. The assessment was centralized and was made by an external panel.

RESULTS

In all, 30 patients had symptomatic neuroendocrine tumors and 16 had asymptomatic neuroendocrine tumors. Five patients in the group with symptomatic tumors and two in the group with nonsymptomatic tumors were considered not to be evaluable. The mean duration of treatment was 12 months in the group with symptomatic tumors and 13 months in the other group. Among the 39 evaluable patients, two objective responses were obtained, giving an objective response rate of 5% (one in the group with symptomatic tumors and one in the other group). Nineteen patients had no significant increase in their tumor size for a mean of 9.5 months.

CONCLUSIONS

Lanreotide is safe and well tolerated in patients with carcinoid tumors. It seems to have both symptomatic and antitumoral effects in this setting.

Octreotide acetate long-acting release in patients with metastatic neuroendocrine tumors pretreated with lanreotide

BACKGROUND

In the present study we investigated the efficacy and tolerability of i.m. octreotide acetate (octreotide LAR) in patients with metastatic neuroendocrine tumors (NETs) previously treated and failed on i.m. lanreotide.

PATIENTS AND METHODS

Fifteen patients (8 females, 7 males, median age 67 years, range 28-81 years) with metastatic NETs (8 endocrine pancreatic tumors, 7 midgut carcinoids) were enrolled in the study. All patients were in progressive disease (objective: 11 patients, symptomatic: 10 patients, biochemical: 11 patients) after treatment with slow release lanreotide, 30 mg every 14 days for a median time of 8 months (range 3-19 months). All patients had measurable disease; 12 patients had elevated serum and/or urine markers and 11 were symptomatic. Octreotide scintigraphy was positive in 13 of 15 patients. Octreotide LAR was administered as i.m. injection at the dose of 20 mg every four weeks until disease progression.

RESULTS

An objective partial response (PR) was documented in one patient (7%), no change (NC) in six (40%), and progressive disease (PD) in eight patients (53%). The PR was observed in one patient with non-functioning endocrine pancreatic tumor with progressive liver and lymph node metastases after 16 months of i.m. lanreotide therapy. The median duration of disease stabilization was 7.5 months (range 6-12+ months). The overall biochemical response rate was 41%, including CRs (33%) and PRs (8%); biochemical responses were observed in carcinoids as well as in endocrine pancreatic tumors; the median duration of response was 5 months for CRs and 7.5 months for PRs. The overall symptomatic response rate was 82%. The median duration of response for diarrhoea, abdominal pain, or both was 6.5 months (range 3-12+ months). Improvement in performance status (PS) was obtained in 5 of 11 patients with PS of 1 at study entry. Median duration of octreotide LAR treatment was seven months (range 3-12+ months). No serious adverse events were reported; mild side effects were reported in 26% of patients.

CONCLUSIONS

Octreotide LAR 20 mg shows significant efficacy in terms of objective response rate (PR + SD), biochemical and symptomatic control in patients with metastatic NETs of the GEP system pretreated and progressing on slow release lanreotide.

Long-acting depot lanreotide in the treatment of patients with advanced neuroendocrine tumors

Long-acting depot forms of somatostatin analogs administered by intramuscular injections are now available for the treatment of neuroendocrine tumors (NETs). In the present study, we investigated the efficacy and tolerability of a slow-release form of lanreotide in patients with advanced NETs. From July 1996 to January 1999, 25 patients with advanced NETs (12 carcinoids, 13 endocrine pancreatic tumors) were enrolled in the study. Thirteen patients were pretreated with subcutaneous octreotide, chemotherapy, or hepatic metastasis alcoholization. All the patients had measurable disease. Seventeen patients were symptomatic and 20 patients had elevated serum and/or urine markers. Octreotide scintigraphy was positive in 23 of 25 patients. Lanreotide was administered as intramuscular injections at the dose of 30 mg every 2 weeks until there was objective, biochemical, or symptomatic tumor progression. Objective partial responses (PRs) were documented in 2 patients (8%), whereas 10 patients (40%) had tumor stabilization. The PRs were observed in patients with midgut carcinoids, of whom one was pretreated with subcutaneous octreotide. The response duration was 21+ and 24+ months in responding patients; the median duration of disease stabilization was 8.5 months (range, 4-21+). The overall biochemical response rate was 42%, including 2 complete responses (CRs) (10.5%) and 6 PRs (31.5%); all biochemical responses were observed mostly in patients with carcinoid tumors; the duration of response was 18+ and 30+ months for CRs; the median duration of biochemical response was 7 months (range, 4-18+) for PRs. The overall symptomatic response rate was 70% with a median duration of 7.5, 18, and 18+ months for diarrhea, abdominal pain, and flushing, respectively. Median duration of lanreotide treatment was 10 months (range, 2-30+). No significant side effects were reported. Depot lanreotide 30 mg shows significant efficacy in terms of objective response rate and in biochemical and symptomatic control, in pretreated patients as well as nonpretreated patients with advanced NETs. Tolerability is good, with good patient compliance.