Metastatic carcinoid tumors and the malignant carcinoid syndrome

The cause-and-effect relationship between gut microbiota abundance and carcinoid syndrome: a bidirectional Mendelian randomization study

Objective

Carcinoid syndrome (CS) commonly results from neuroendocrine tumors. While active substances are recognized as the main causes of the typical symptoms such as diarrhea and skin flush, the cause-and-effect relationship between gut microbiota abundance and CS remains unclear.

Methods

The Single Nucleotide Polymorphisms (SNPs) related to gut microbiota abundance and CS were obtained from the GWAS summary data. The inverse variance weighted (IVW) method was used to assess the causal relationship between gut microbiota abundance and CS. Additionally, the MR-Egger, Weighted Median model, and Weighted model were employed as supplementary approaches. The heterogeneity function of the TwoSampleMR package was utilized to assess whether SNPs exhibit heterogeneity. The Egger intercept and Presso test were used to assess whether SNPs exhibit pleiotropy. The Leave-One-Out test was employed to evaluate the sensitivity of SNPs. The Steiger test was utilized to examine whether SNPs have a reverse causal relationship. A bidirectional mendelian randomization (MR) study was conducted to elucidate the inferred cause-and-effect relationship between gut microbiota abundance and CS.

Results

The IVW results indicated a causal relationship between 6 gut microbiota taxa and CS. Among the 6 gut microbiota taxa, the genus Anaerofilum (IVW OR: 0.3606, 95%CI: 0.1554-0.8367, p-value: 0.0175) exhibited a protective effect against CS. On the other hand, the family Coriobacteriaceae (IVW OR: 3.4572, 95%CI: 1.0571-11.3066, p-value: 0.0402), the genus Enterorhabdus (IVW OR: 4.2496, 95%CI: 1.3314-13.5640, p-value: 0.0146), the genus Ruminiclostridium6 (IVW OR: 4.0116, 95%CI: 1.2711-12.6604, p-value: 0.0178), the genus Veillonella (IVW OR: 3.7023, 95%CI: 1.0155-13.4980, p-value: 0.0473) and genus Holdemanella (IVW OR: 2.2400, 95%CI: 1.0376-4.8358, p-value: 0.0400) demonstrated a detrimental effect on CS. The CS was not found to have a reverse causal relationship with the above 6 gut microbiota taxa.

Conclusion

Six microbiota taxa were found to have a causal relationship with CS, and further randomized controlled trials are needed for verification.

Efficacy, safety and unmet needs of evolving medical treatments for carcinoid syndrome

This review reports on the currently available medical treatment options for the control of symptoms due to carcinoid syndrome in patients with neuroendocrine tumors. The efficacy and adverse events (AEs) of approved drugs such as somatostatin analogues (SSA), telotristat ethyl (TE) and interferon-alpha, are reviewed. Somatostatin analogues remain the standard treatment of carcinoid syndrome based on the high expression of somatostatin receptors and the resulting inhibition of secretion of bioactive compounds; their use is associated with relatively mild AEs, involving mainly the gastrointestinal system, and being usually transient. Although dose escalation of SSA remains an unapproved option, it is clinically implemented to alleviate symptoms in refractory carcinoid syndrome and supported by the most recent guidelines. The side effects associated with the increased dose are in general mild and consistent with standard dose of SSA. Telotristat ethyl, an oral inhibitor of tryptophan hydroxylase, the rate-limiting enzyme in serotonin biosynthesis, represents a rather novel innovative treatment option in patients with carcinoid syndrome suffering from diarrhea and complements the standard therapy of SSA. Given the low toxicity profile, TE may be considered an early add-on treatment to SSA in patients with uncontrolled carcinoid syndrome. However, further prolonged follow-up of patients treated with TE may be needed to exclude potential AEs, such as liver toxicity or depressed mood, in patients with long-term treatment. Interferon alpha is a cytokine with direct inhibitory effect on hormone secretion and tumor cell proliferation and an approved therapy in carcinoid syndrome but is associated with significant AEs in the majority of the patients requiring frequently dose reduction. The finding of a more favorable tolerability of pegylated interferon needs to be confirmed in a prospective study.

In patients with well-differentiated neuroendocrine tumours, there is no apparent benefit of somatostatin analogues after disease control by peptide receptor radionuclide therapy

PURPOSE

Peptide receptor radionuclide therapy (PRRT) and somatostatin analogues (SSAs) are commonly combined as primary treatment for neuroendocrine neoplasms (NEN), and SSAs given as maintenance. We sought to evaluate whether sequential therapy with PRRT followed by SSAs has progression or survival benefits in patients with NEN after disease control by PRRT.

METHODS

This prospective, randomised, single-centre study had as principal eligibility criteria: unresectable, locally advanced, or metastatic, histologically confirmed well-differentiated NEN; no symptoms/biochemical diagnosis of carcinoid syndrome; no SSAs or ≤ 3 months of SSAs before PRRT; and stable disease or partial or complete response after PRRT. Altogether, 115 patients were randomised 2:1 to an SSA group (n = 74) given octreotide acetate LAR every 4 weeks, or a control group (n = 41) receiving only best supportive care. Octreotide treatment was to stop upon intolerable toxicity or patient refusal, or, at physician/patient discretion, upon NEN progression. The primary endpoint was progression-free survival (PFS), the secondary endpoint, and overall survival (OS).

RESULTS

Median (25th-75th percentile) follow-up from the first PRRT activity to death or latest observation was 6.6 (3.18-10.22) years. During that time, 71/115 patients (62%) progressed, 52/74 (70%) in the SSA group, and 19/41 (46%) in the control group (p = 0.01). Eighty-eight/115 patients (76%) died, 58/74 (78%) in the SSA group, and 30/41 (73%) in the control group (p = 0.52). Median (95% CI) PFS was 4.7 (2.8-7.7) years in the SSA group, and 6.4 (4.1-not reached) years in controls. Overall, median OS was 6.6 years. Neither PFS nor OS differed between groups (p = 0.129, p = 0.985, respectively).

CONCLUSIONS

In patients with disease control after PRRT, subsequent SSA treatment appeared not to be associated with better PFS or OS. Whether to continue SSA administration upon progression after PRRT requires evaluation in a prospective, randomised, controlled multicentre study with a relatively homogeneous sample.

Carcinoid heart disease: current understanding and future directions

Carcinoid tumors are rare and aggressive malignancies. A multitude of vasoactive agents are central to the systemic effects of these tumors. The additional burden of cardiac dysfunction heralds a steep decline in quality of life and survival. Unfortunately, by the time carcinoid syndrome surfaces clinically, the likelihood of cardiac involvement is 50%. Although medical therapies such as somatostatin analogues may provide some symptom relief, they offer no mortality benefit. On the other hand, referral to surgery following early detection has shown increased survival. The prompt recognition of this disease is therefore of the utmost importance.

Illuminating somatostatin analog action at neuroendocrine tumor receptors

Somatostatin analogs for the diagnosis and therapy of neuroendocrine tumors (NETs) have been used in clinical applications for more than two decades. Five somatostatin receptor subtypes have been identified and molecular mechanisms of somatostatin receptor signaling and regulation have been elucidated. These advances increased understanding of the biological role of each somatostatin receptor subtype, their distribution in NETs, as well as agonist-specific regulation of receptor signaling, internalization, and phosphorylation, particularly for the sst2 receptor subtype, which is the primary target of current somatostatin analog therapy for NETs. Various hypotheses exist to explain differences in patient responsiveness to somatostatin analog inhibition of tumor secretion and growth as well as differences in the development of tumor resistance to therapy. In addition, we now have a better understanding of the action of both first generation (octreotide, lanreotide, Octreoscan) and second generation (pasireotide) FDA-approved somatostatin analogs, including the biased agonistic character of some agonists. The increased understanding of somatostatin receptor pharmacology provides new opportunities to design more sophisticated assays to aid the future development of somatostatin analogs with increased efficacy.

Prognostic validity of the American Joint Committee on Cancer staging classification for midgut neuroendocrine tumors

PURPOSE

The American Joint Committee on Cancer (AJCC) staging manual has introduced a TNM staging classification for jejunal-ileal (midgut) neuroendocrine tumors (NETs). This classification has not been validated in a population consisting solely of midgut NETs. The purpose of this study was to test the prognostic validity of the classification in such a population.

METHODS

Patients with jejunal and ileocecal NETs who were treated at the Moffitt Cancer Center between 2000 and 2010 were assigned stages (I through IV). Kaplan-Meier analyses for overall survival (OS) were performed on the basis of TNM stage and pathologic grade. Multivariate modeling was performed using Cox proportional hazards regression.

RESULTS

We identified 691 patients with jejunal-ileocecal NETs. The AJCC classification in aggregate was highly prognostic for OS (P < .001). Five-year OS rates for stages I through IV were 100%, 100%, 91%, and 72%, respectively. The survival difference between stages III and IV was significant (P < .001); the difference between stages I/II versus III was not statistically significant (P = .1). Among patients with stage IIIB tumors, 5-year survival rates were 95% for resectable tumors versus 78% for unresectable mesenteric tumors (P = .02). A proliferative threshold of five mitoses per 10 high-power fields (HPF) was of greater prognostic value than a threshold of two mitoses per 10 HPF for discriminating between low- and intermediate-grade tumors.

CONCLUSION

Stage I and II midgut NETs are associated with identical survival rates. Stage IIIB tumors are heterogeneous, with significant differences in survival observed between resectable mesenteric lymph nodes versus unresectable masses in the root of the mesentery. A higher mitotic cutoff of five per 10 HPF may lead to improved prognostic differentiation between low- and intermediate-grade tumors. Revisions to the current AJCC staging and grading classification may be warranted.

Carcinoid heart disease

Carcinoid tumors are rare, indolent neuroendocrine tumors that are often associated with a syndrome characterized by episodic flushing, secretory diarrhea, bronchospasm, and hypotension-the carcinoid syndrome. Cardiac involvement occurs in one-half to two-thirds of patients with carcinoid syndrome and is associated with a worse clinical outcome. Carcinoid heart disease is characterized by endocardial plaque-like deposits found predominantly on right-sided heart valves, leading to the combination of valvular stenosis and regurgitation. Left-sided cardiac involvement can also occur in <10% of patients. Somatostatin analogs form the therapeutic cornerstone in the medical management of these patients. Cytotoxic chemotherapy has had only limited success in the treatment of metastatic carcinoid tumors. Hepatic resection or palliative cytoreduction may be of benefit in patients with limited hepatic disease. Hepatic artery embolization is usually applied if a patient is not eligible for surgical debulking. The development and progression of carcinoid heart disease are associated with an unfavorable outcome. In those patients having severe cardiac involvement and well-controlled systemic disease, valve replacement surgery has been found to be an effective treatment that can both relieve intractable symptoms and contribute to improved clinical outcomes.

The role of angiogenesis in neuroendocrine tumors

The first studies to assess in vitro angiogenesis in neuroendocrine tumors used animal-based assays to study the antiangiogenic properties of somatostatin analogs. Current technologies enable investigators to directly appraise the in vitro angiogenic response of an individual's neuroendocrine tumor with and without potential antiangiogenic reagents. This article describes the evolution of methods to assess in vitro angiogenesis in neuroendocrine tumors and describes some of the clinical data.

Carcinoid heart disease

The carcinoid syndrome is usually evident when enterochromaffin (EC) cell-derived neuroendocrine tumors (carcinoids) metastasize to the liver. In addition to carcinoid symptomatology, about 40% of patients exhibit carcinoid heart disease (CHD) with fibrotic endocardial plaques and associated heart valve dysfunction. The mechanism behind CHD development is not fully understood, but serotonin (5-HT) is considered to be a major initiator of the fibrotic process. Most patients present with right-sided heart valve dysfunction since pulmonary and tricuspid valves lesions are the most common (>95%) cardiac pathology. Left-sided valvular involvement, and angina associated with coronary vasospasm occur in ~10% of subjects with CHD. Pathognomonic echocardiograpic features include immobility of valve leaflets and thickening and retraction of the cusps most commonly resulting in tricuspid valve regurgitation and pulmonary stenosis. Therapeutic options include cardioactive pharmacotherapy for heart failure and, in selected individuals, cardiac valve replacement. Previously valve replacement was reserved for advanced disease due to a perioperative mortality of >20% however in the last decade, technical advances as well as an earlier diagnosis have decreased surgical mortality to <10% and valve replacements are undertaken more frequently. A recent analysis of 200 cases demonstrated an increase in median survival from 1.5 years to 4.4 years in the last two decades. Although the improved prognosis might also reflect the increased use of surgical cytoreduction, hepatic metastatic ablative therapies and somatostatin analogs a robust correlation between diminution of circulating tumor products and an increased long-term survival in CHD has not been rigorously demonstrated.

Correlation of chromogranin A levels and somatostatin receptor scintigraphy findings in the evaluation of metastases in carcinoid tumors

OBJECTIVE

Chromogranin A (CgA) has been gaining acceptance as a helpful tumor marker in patients with neuroendocrine tumors, with respect to both diagnosis and prognosis. The objective of this study was to correlate serum CgA levels and somatostatin receptor scintigraphy (SRS) findings in the evaluation of metastases in carcinoid tumors.

MATERIALS AND METHODS

A total of 125 patients(61 men and 64 women, aged from 23 to 84 years) with histologically diagnosed carcinoid tumor underwent serum CgA assay and SRS for detecting metastasis or disease recurrence. The quantitative determination of CgA was performed in serum using an enzyme immunoassay with a cut-off value fixed at 39 U/l. Scintigraphies were performed with 200-220 MBq of In-111-DTPA-Phel-octreotide including whole-body images as well as single-photon emission computed tomography and computed tomography scans of the chest and abdomen.

RESULTS

The primary tumors originated from the gastrointestinal tract in 115 of 125 patients (92.0%), the lung in 7 of 125 patients (5.6%), the kidney in 2 of 125 patients (1.6%), and the breast in 1 of 125 patients (0.8%). The primary tumors originated from the foregut, midgut, and hindgut in 13.6%, 71.2%, and 12.8%, respectively. Correlation of SRS with other imaging modalities and clinical follow-up findings revealed a sensitivity, a specificity, and an accuracy of 82.9%, 97.7%, and 88.0%, respectively, and for CgA 62.2%, 83.7%, and 69.6%, respectively. There was 1 false-positive and 14 false-negative SRS results and 7 false-positive and 31 false-negative CgA analyses. SRS demonstrated higher sensitivity, specificity, and accuracy than CgA for the evaluation of metastatic carcinoid tumors. The concordance between SRS and CgA results was 67.2%. Discrepancies, such as positive SRS with normal CgA levels, were noted in 26 (20.8%) cases, whereas negative SRS with high CgA levels was seen in 15 (12.0%) cases. Combining the results of CgA and SRS increased the sensitivity (92.7%) but decreased the specificity (81.4%) of tumor detection.

CONCLUSIONS

In our study, SRS proved to be more sensitive, more specific, and more accurate than CgA for metastatic evaluation of carcinoid tumors. Positive SRS correlated with elevation of serum CgA levels. Serum CgA might have some diagnostic utility in patients with negative SRS studies. Nevertheless, both SRS and CgA should be considered useful tools in the evaluation of metastases in carcinoid patients.

Peptide receptor expression in GEP-NET

Numerous peptide receptors have recently been reported to be expressed or overexpressed in various human cancers. For instance, somatostatin receptors are particularly frequently expressed in gastroenteropancreatic neuroendocrine tumors (GEP-NET), including both primaries and metastases. The density is often high, and the distribution is usually homogenous. While various somatostatin receptor subtypes can be expressed in these tumors, the sst(2) is clearly predominant. These receptors represent the molecular basis for a number of clinical applications, including symptomatic therapy with octreotide in hormone-secreting GEP-NET, in vivo diagnostic with radiolabeled diethylene triamine pentaacetic acid octreotide (Octreoscan) to evaluate the extend of the disease, and (90)Y- or (177)Lu-[(90)Y-DOTA]-D: -Phe(1)-Tyr(3) octreotide radiotherapy. GEP-NET can, however, express peptide receptors other than somatostatin receptor: Insulinomas have more glucagon-like peptide 1 receptors than somatostatin receptors; gastrinomas express very high levels of secretin receptors. GEP-NET may also express cholecystokinin 2, bombesin, neuropeptide Y, or vasoactive intestinal peptide receptors. Often, several of these peptide receptors are expressed simultaneously in GEP-NET, providing a molecular basis for in vivo multireceptor targeting of those tumors.

Carcinoid heart disease

Carcinoid heart disease is a rare form of valvular heart disease. The management of these patients is complex, as the systemic malignant disease and the cardiac involvement have to be considered at the same time. Progress in the treatment of patients with carcinoid disease has resulted in improved symptom control and survival. Development and progression of carcinoid heart disease are associated with increased morbidity and mortality. In patients with severe cardiac involvement and well-controlled systemic disease, cardiac surgery has been recognized as the only effective treatment option. Valve replacement surgery may not only be beneficial in terms of symptom relief, but may also contribute to the improved survival observed over the past 2 decades in patients with carcinoid heart disease. Early diagnosis and early surgical treatment in appropriately selected patients may provide the best results. In this article, we review the current literature regarding the biology, diagnosis, treatment, and prognosis of carcinoid heart disease.

Role of somatostatin analogs in the clinical management of non-neuroendocrine solid tumors

The somatostatin analogs octreotide, lanreotide and RC-160 (vapreotide) are known to have direct and indirect antitumor effects. Direct effects include the arrest of tumor growth and stimulation of apoptosis, resulting in tumor shrinkage. Indirect antiproliferative effects may occur through antiangiogenesis, immunomodulatory effects and the suppression of tumor-stimulating growth factors. With a safety profile of somatostatin analogs established over 20 years of clinical use in the treatment of neuroendocrine tumors, somatostatin analogs are attractive therapeutic options for patients with non-neuroendocrine tumors. In early clinical trials of somatostatin analogs, however, some cancer patients responded well, while others showed a lack of benefit. This variability in clinical response may reflect the selective binding affinities of octreotide, lanreotide and RC-160, which bind with high affinity to just two of the five different somatostatin receptor subtypes. Treatment response may therefore depend on the specific receptor subtype(s) present in the tumor, the relative proportion of receptor(s) expressed on the tumor cell surface and the absolute quantity of each receptor subtype. Greater understanding of the role of somatostatin receptors, their binding affinities and modes of action has led to increased research into the use of somatostatin analogs, particularly octreotide, in cancer treatment as monotherapies, in combination with hormonal treatments and cytotoxic therapies, and in both adjuvant and neoadjuvant settings. A review of the literature suggests that the antitumor potential of somatostatin analogs should be investigated further and additional studies might determine how these analogs can best be used to improve the treatment of patients with non-neuroendocrine tumors.

Survival and response after peptide receptor radionuclide therapy with [90Y-DOTA0,Tyr3]octreotide in patients with advanced gastroenteropancreatic neuroendocrine tumors

Because the role of chemotherapy, interferon, or somatostatin analogs as antiproliferative agents is uncertain, currently few treatment options exist for patients with metastatic or inoperable gastroenteropancreatic neuroendocrine tumors (GEP-NET). Fifty-eight patients with somatostatin receptor-positive GEP-NET were treated in a phase I dose-escalating study with cumulative doses of 47 mCi to 886 mCi of the radiolabeled somatostatin analog [(90)Y-DOTA(0),Tyr(3)]-octreotide. At baseline, 47 patients had progressive disease, and 36 were symptomatic. The extent of disease was: 4 patients without liver metastases and 52 patients with liver metastases, including 16 patients with very advanced disease, qualified as "end-stage," and 2 end-stage patients without liver metastases. The objective responses were 5 partial response (PR), 7 minor response (MR), 29 stable disease (SD), and 17 PD. Overall, 33 patients (57%) experienced some improvement in their disease status, including conversion from PD into SD and improvement from SD into MR. Accordingly, 21 of 36 patients (58%) had improvement in Karnofsky performance score or symptoms. The median overall survival (OS) was 36.7 months (95% confidence interval [CI] 19.4-54.1 months). The median progression-free survival in 41 patients who had at least stable disease at the end of the treatment period was 29.3 months (95% CI 19.3-39.3 months). Patients who had SD at baseline had a significantly better OS than patients who had PD at baseline. The extent of disease at baseline also was a significant predictive factor for OS. The OS after therapy with [(90)Y-DOTA(0),Tyr(3)]-octreotide was significantly better than in a historic control group of 32 comparable patients with GEP-NET who had been treated with another radiolabeled somatostatin analog, [(111)In-DTPA(0)]-octreotide (median OS 12.0 months, 95% CI 6.2-17.8 months). The difference in OS for both therapies remained highly significant in a multivariate Cox proportional hazard model including progression status and extent of disease at baseline as covariates. Although the objective response after therapy with [(90)Y-DOTA(0),Tyr(3)]-octreotide by standard criteria seems modest, the significantly longer OS compared with historic controls is most encouraging.

Scintigraphic detection of carcinoid tumors with a cost effectiveness analysis

AIM: To evaluate the diagnostic sensitivity and accuracy and the cost-effectiveness of this technique in the detection of gastroenteropancreatic carcinoid tumors and their metastases in comparison with conventional imaging methods.

METHODS: Somatostatin receptor scintigraphy (SRS) was performed in 24 patients with confirmed carcinoids and 7 under investigation. The results were compared with those of conventional imaging methods (chest X-ray, upper abdominal ultrasound, chest CT, upper and lower abdominal CT). Also a cost-effectiveness analysis was performed comparing the cost in Euro of several combinations of SRS with conventional imaging modalities.

RESULTS: SRS visualized primary or metastatic sites in 71.0% of cases and 61.3% of conventional imagings. The diagnostic sensitivity of the method was higher in patients with suspected lesions (85.7% vs 57.1%). SRS was less sensitive in the detection of metastatic sites (78.9% vs 84.2%). The undetectable lesions by SRS metastatic sites were all in the liver. Between several imaging combinations, the combinations of chest X-ray/upper abdominal CT/SRS and chest CT/upper abdominal CT/SRS showed the highest sensitivity (88.75%) in terms of the number of detected lesions. The combinations of chest X-ray/upper abdominal US/SRS and chest CT/upper abdominal ultrasound/SRS yielded also a quite similar sensitivity (82%). Compared to the cost of the four sensitive combinations the combination of chest X-ray/upper abdominal ultrasound/SRS presented the lower cost, 1183.99 Euro vs 1251.75 Euro for chest CT/upper abdominal ultrasound/SRS, 1294.93 Euro for chest X/ray/upper abdominal CT/SRS and 1362.75 Euro for chest CT/upper abdominal CT/SRS.

CONCLUSION: SRS imaging is a very sensitive method for the detection of gastroenteropancreatic carcinoids but is less sensitive than ultrasound and CT in the detection of liver metastases. Between several imaging combinations, the combination of chest X-ray/upper abdominal CT/SRS shows the highest sensitivity with a cost of 1294.93 Euro.

Clinical usefulness of 99mTc-EDDA/HYNIC-TOC scintigraphy in oncological diagnostics: a pilot study

The clinical usefulness of a new 99mTc-labeled somatostatin analogue has been studied from the standpoint of oncological diagnostics. The group of patients studied included 40 individuals with diagnosed malignant neoplasms (32 primary and 8 metastatic). Among the primary tumors were 7 pituitary adenomas (5 hormonally active and 2 inactive), 1 liposarcoma, 2 carcinoids, 1 breast carcinoma, and 21 cases of lung cancer (2 small cell and 19 non-small cell) were represented. The metastatic tumors consisted of: 3 malignant melanomas, 1 pheochromocytoma, 1 prostatic cancer, 1 leiomyosarcoma, 1 pancreatic carcinoma ectopically secreting ACTH, and 1 carcinoid of the thymus. The radiopharmaceutical, 99mTc-EDDA/HYNIC-octreotide, was i.v. administered at the activity of 740-925 MBq. The imaging was comprized of a whole-body scan and single photon emission computed tomography. Positive scintigrams were obtained in 4 of 5 hormonally active pituitary adenomas, in 1 of 2 cases of carcinoid, in liposarcoma, breast cancer, and all cases of small cell (SCLC) and non-small cell lung cancer (NSCLC). The neoplastic metastases were visualized in 2 of 3 cases of melanoma and in patients with pheochromocytoma, pancreatic carcinoma secreting ACTH, and thymic carcinoid. Scintigrams were negative in both hormonally inactive pituitary adenomas, in one case of metastatic malignant melanoma, leiomyosarcoma, and in cases of metastasis from the prostatic carcinomas. The results of this pilot study indicated that 99mTc-EDDA/HYNIC-TOC is a potentially useful radiopharmaceutical for the imaging of a wide range of primary and metastatic tumors. More detailed indications for the clinical usefulness of the new tracer for the imaging of selected tumor types require studies on much larger groups of patients. Special attention should be paid to the successful imaging of all cases of NSCLC.

Topotecan in patients with advanced neuroendocrine tumors: a phase II study with significant hematologic toxicity

New agents with antitumor activity in neuroendocrine tumors are sorely needed. We therefore conducted a phase II study of topotecan (TOPA) 1.5 mg/m2/d for 5 days every 3 weeks in 22 patients with advanced carcinoid and islet cell tumors. Severe neutropenia in 8 of 11 patients (72%) prompted a 30% dose reduction of TOPA to 1.05 mg/m2 for the final 11 patients enrolled. No objective responses were observed. Eighteen patients have progressed and 14 have died. The median time to progression was 4.2 months (95% CI: 2.9-6.5) and the median survival was 1.9 years (95% CI: 0.63-2.3). Hematologic adverse events were significant, with 16 of 22 patients developing grade IV neutropenia; however, there were no septic deaths. Nonhematologic adverse events were infrequent and were not dose limiting. In conclusion, further studies of this schedule of TOPA in this patient population are not recommended due to the lack of tumor response and significant hematologic toxicity.

Somatostatin and other Peptide receptors as tools for tumor diagnosis and treatment

Somatostatin receptors are expressed in selected human cancers. They are particularly frequently expressed in gastroenteropancreatic neuroendocrine tumors (GEP NET), including both primaries and metastases. The density is often high, the distribution is usually homogeneous. While various somatostatin receptor subtypes can be expressed in these tumors, sst2 is clearly predominant. These receptors represent the molecular basis for a number of clinical applications, including symptomatic therapy with cold octreotide in hormone-secreting GEP NET, in vivo diagnostic with Octreoscan to evaluate the extend of the disease, and 90Y-DOTATOC radiotherapy. GEP NET can, however, express peptide receptors other than somatostatin receptors: insulinomas have more glucagon-like peptide 1 receptors than somatostatin receptors, gut NET (carcinoids) may also express cholecystokinin 2, bombesin or vasoactive intestinal peptide receptors. Often, several of these peptide receptors are expressed simultaneously in GEP NET, providing a molecular basis for in vivo multireceptor targeting of those tumors.

Peptide receptors as molecular targets for cancer diagnosis and therapy

During the past decade, proof of the principle that peptide receptors can be used successfully for in vivo targeting of human cancers has been provided. The molecular basis for targeting rests on the in vitro observation that peptide receptors can be expressed in large quantities in certain tumors. The clinical impact is at the diagnostic level: in vivo receptor scintigraphy uses radiolabeled peptides for the localization of tumors and their metastases. It is also at the therapeutic level: peptide receptor radiotherapy of tumors emerges as a serious treatment option. Peptides linked to cytotoxic agents are also considered for therapeutic applications. The use of nonradiolabeled, noncytotoxic peptide analogs for long-term antiproliferative treatment of tumors appears promising for only a few tumor types, whereas the symptomatic treatment of neuroendocrine tumors by somatostatin analogs is clearly successful. The present review summarizes and critically evaluates the in vitro data on peptide and peptide receptor expression in human cancers. These data are considered to be the molecular basis for peptide receptor targeting of tumors. The paradigmatic peptide somatostatin and its receptors are extensively reviewed in the light of in vivo targeting of neuroendocrine tumors. The role of the more recently described targeting peptides vasoactive intestinal peptide, gastrin-releasing peptide, and cholecystokinin/gastrin is discussed. Other emerging and promising peptides and their respective receptors, including neurotensin, substance P, and neuropeptide Y, are introduced. This information relates to established and potential clinical applications in oncology.

Development of a novel in vitro human tissue-based angiogenesis assay to evaluate the effect of antiangiogenic drugs

OBJECTIVE

To describe a novel in vitro human tissue-based angiogenic model that can predict an individual tumor's response to antiangiogenic drugs.

SUMMARY BACKGROUND DATA

A number of in vitro and in vivo angiogenesis assays exist, but they do not provide potentially useful information for the treatment of an individual patient. Clonogenic assays have been used to evaluate the response of an individual's tumor to antineoplastic agents, but these tumor fragments are cultured in an environment that does not lead to neovessel growth. The authors have previously demonstrated that human vein disks or human tumor xenograft fragments incorporated into a 0.3% fibrin-thrombin clot will develop angiogenic vessel growth from the cut edge of the vessel disk or xenograft fragment.

METHODS

Fresh human tumor or normal tissue disks (2 x 1 mm) from fresh surgical specimens were incorporated into fibrin-thrombin clots overlain with nutrient medium containing either 20% fetal bovine serum alone or in combination with Epothilone B, a tubulin inhibitor with antiangiogenic properties. Tissue disks were visually assessed over time to determine the percentage of wells that developed an angiogenic response. Neovessel growth, density, and length were graded at intervals using a semiquantitative visual neovessel growth-rating scheme (angiogenic index, 0-16 scale) devised in the authors' laboratory.

RESULTS

Epothilone B treatment at doses of 10-6 mol/L and 10-8 mol/L decreased the number of wells that developed an invasive angiogenic response and limited the development of vessels that invaded the matrix. At these doses, Epothilone B also caused regression of vessels in wells that had been allowed to develop an angiogenic response. Treatment of tumors or normal tissues with Epothilone B at doses less than 10-8 mol/L was ineffective.

CONCLUSIONS

Epothilone B may be an effective antiangiogenic agent in a variety of tumor types. The authors speculate that this in vitro model might provide useful information to the clinician on the effect of specific antiangiogenic agents on individual tumors. This may be particularly useful in patients with tumors that, as a group, are unresponsive to treatment with antineoplastic agents.

Indium-111-pentetreotide prolongs survival in gastroenteropancreatic malignancies

Somatostatin and its analogues bind to somatostatin receptors (sst) 1 through 5 that are overexpressed in neuroendocrine neoplasms such as gastroenteropancreatic (GEP) malignancies. After ligand-receptor binding, a fraction of the ligand-receptor complexes internalize. This internalization process is an effective means of delivering cytotoxic radiolabeled somatostatin analogues, especially those emitting short-range decay particles such as Auger electrons, to the neoplastic cell nucleus. Indium-111-pentetreotide, an sst 2 preferring somatostatin analogue with gamma and Auger electron decay characteristics, is commonly used for the scintigraphic evaluation and management of neuroendocrine cancer patients. This clinical trial was performed to determine the effectiveness and tolerability of therapeutic doses of (111)In-pentetreotide in patients with GEP tumors. GEP tumor patients who had failed all forms of conventional therapy, with worsening of tumor-related signs and symptoms and/or radiographically documented progressive disease, an expected survival less than 6 months, and sst positivity as determined by the uptake on a 6.0 mCi (111)In-pentetreotide scan (OctreoScan; Mallinckrodt Medical, Inc, St. Louis, MO), were treated with at least 2 monthly 180-mCi intravenous injections of (111)In-pentetreotide. Baseline clinical assessments, serum chemistries, and plasma pancreastatin levels were measured and repeated before each (111)In-pentetreotide treatment. From February 1997 to February 1998, 27 GEP (24 carcinoid neoplasms with carcinoid syndrome and 3 pancreatic islet cells) patients were accrued, with 26 patients evaluable for clinical and radiographic responses, 21 patients evaluable for biochemical assessments, and 27 patients evaluable for survival analysis and safety. Toxicity was evaluated by using standard National Cancer Institute (NCI) Common Toxicity Criteria guidelines. Clinical benefit occurred in 16 (62%) patients. Pancreastatin levels decreased by 50% or more in 81% of the patients. Objective partial radiographic responses occurred in 2 (8%) patients, and significant tumor necrosis (defined by 20 Hounsfield units or greater decrease from baseline) developed in 7 (27%) patients. The following transient Grades 3/4 NCI Common Toxicity Criteria side effects were observed, respectively: leukocyte: 1/1; platelets: 0/2; hemoglobin: 3/0; bilirubin: 1/3; creatinine: 1/0; neurologic: 1/0. Myeloproliferative disease and/or myelodysplastic syndrome have not been observed in the 6 patients followed-up for 48+ months. The median survival was 18 months (range, 3-54+ mo). Two doses (180 mCi) of (111)In-pentetreotide are safe, well-tolerated, and improve symptoms in 62% of patients, decrease hormonal markers in 81% of patients, decrease Hounsfield units on computed tomography (CT) scans in 27% of patients, with 8% partial radiographic responses and increased expected survival in GEP cancer patients with somatostatin receptor-expressing tumors. The maximal tolerated dose of (111)In-pentetreotide and the optimal dosing schedules remain under investigation.

A Phase II study of high-dose paclitaxel in patients with advanced neuroendocrine tumors

BACKGROUND

New agents with antitumor activity in patients with neuroendocrine tumors are sorely needed. A Phase II study of high-dose paclitaxel in patients with metastatic carcinoid and islet cell tumors was performed at the Mayo Clinic. Granulocyte-colony-stimulating factor (GCSF) also was administered to ameliorate neutropenia.

METHODS

Twenty-four patients (14 with carcinoid tumors, 9 with islet cell tumors, and 1 with an anaplastic tumor) were enrolled on this Phase II study of paclitaxel given as a 24-hour continuous infusion at a dose of 250 mg/m(2) every 3 weeks plus GCSF at a dose of 5 microg/kg/day subcutaneously, beginning 24 hours after the completion of the paclitaxel dose and continuing until the absolute neutrophil count was > 10,000/microL.

RESULTS

All 24 patients were evaluable for analysis. The overall response rate was 8% (95% confidence interval [95% CI], 0-0.11). At last follow-up all patients except 1 had developed disease progression, with an estimated median time to disease progression of 3.2 months (95% CI, 1.6-6.0 months). The estimated median survival was 1.5 years (95% CI, 1.0-1.8 years). Hematologic toxicity was significant with 12 of 24 patients developing Grade 4 (according to the National Cancer Institute Common Toxicity Criteria scale) neutropenia; however, there were no septic deaths reported. There were 17 episodes of Grade 4 neutropenia in these 12 patients and the duration of these events ranged from 2-5 days. More common nonhematologic toxicities included arthralgia (21 patients), anorexia (15 patients), nausea (15 patients), diarrhea (12 patients), and allergic reactions (2 patients).

CONCLUSIONS

Given the lack of antitumor activity of paclitaxel and the significant hematologic toxicity observed despite the use of GCSF support in the current study cohort of patients with neuroendocrine tumors, further studies of this combination in this particular patient population are not recommended.

Serum pancreastatin levels predict response to hepatic artery chemoembolization and somatostatin analogue therapy in metastatic neuroendocrine tumors

INTRODUCTION

Neuroendocrine tumors often metastasize to the liver and present with disabling hormonal symptoms. Hepatic artery chemoembolization (HACE) combined with somatostatin therapy, pre-embolization, peri-embolization and post-embolization, at doses to control symptoms, is an aggressive approach that can relieve hormonal symptoms with minimal morbidity and mortality.

METHODS

Chemoembolization was performed using 30 mg of adriamycin, 50 mg of mitomycin, 12 ml of hexabrix, 10 ml of ethiodol, and 360-500-microm particles. Pancreastatin, a split product of chromogranin A, was measured pre-HACE and post-HACE in all patients.

RESULTS

Forty-three chemoebolization procedures were performed in 34 symptomatic patients from December 1995 to August 1999. Seventeen patients had intestinal primaries (50%), seven had pancreatic primaries (20%), five had bronchial primaries (15%), and five had unknown primaries (15%). Systemic pancreastatin levels were improved or stable in 31 patients (78%). Symptoms were improved in these 31 patients (78%). Systemic serotonin levels were improved or stable in 24 patients (60%). Radiographic improvement or stability was seen in 18 patients (45%). Procedural related morbidity included pain, fevers, nausea, vomiting, and transient elevations of liver function studies in 75-100% of patients. There was one procedural related mortality (2%). Less than 20% improvement in pancreastatin levels from baseline was associated with death in five of five patients (100%). This was not observed with serotonin levels.

CONCLUSION

Measurement of serum pancreastatin levels is an easy and useful method to predict success in patients who undergo HACE plus somatostatin therapy for metastatic neuroendocrine tumors to the liver. This therapeutic approach is effective in relieving symptoms in 78% of patients, with minimal major morbidity or mortality.

Somatostatin receptor scintigraphy: the definitive technique for characterizing vasoactive intestinal peptide-secreting tumors

Vasoactive intestinal peptide-secreting tumors (VIPomas) are extremely rare and difficult to diagnose. The authors describe a patient who was found to have a VIPoma after 3 years of symptoms. Somatostatin receptor scintigraphy using indium-labeled octreotide localized her tumor and prompted a surgical resection. This is the preferred imaging study for the earliest, most accurate, and cost-effective identification of VIPomas and their metastases.

Scintigraphic long-term follow-up of a patient with metastatic glucagonoma

Two years after resection of a pancreatic glucagonoma, scintigraphy with 111indium-labeled octreotide revealed hepatic metastases in a 48-yr-old man. Hepatic metastases were also visualized by CT, whereas an additional lesion in the chest was seen only by scintigraphy. A total of 11 follow-up examinations over 46 months proved somatostatin receptor scintigraphy to monitor reliably somatostatin receptor expression, growth and dissemination of glucagonoma metastases, and to indicate therapeutic readjustment if necessary. The survival time of the patient is now >75 months, in comparison with a mean survival time of 59 months reported for metastatic glucagonoma.

Prognosis and survival in patients with gastrointestinal tract carcinoid tumors

OBJECTIVE

To determine the impact of clinical presentation variables on the management and survival of patients with gastrointestinal (GI) tract carcinoid tumors.

METHODS

A 20-year (1975-1995) retrospective analysis of 150 patients with GI tract carcinoid tumors at the Massachusetts General Hospital was conducted. Median follow-up was 66 months (range 1-378). Survival estimates for prognostic factors were calculated using Kaplan-Meier product limit estimators, with death from carcinoid as the outcome. Univariate analyses for each factor were obtained using a log-rank test, and multivariate survival analysis was performed.

RESULTS

All but two patients underwent surgical intervention with the intent to cure (90%) or debulk the tumor (9%). Mean age at presentation was 55 +/- 18 years (range 11-90). There was a slight female/male predominance (80:70). Symptoms were nonspecific; the most common were abdominal pain (40%), nausea and vomiting (29%), weight loss (19%), and GI blood loss (15%). Incidental carcinoids, discovered at the time of another procedure, occurred in 40% of patients and were noted at multiple sites throughout the GI tract. The distribution of tumors was ileojejunum (37%), appendix (31 %), colon (13%), rectum (12%), stomach (4%), duodenum (1.3%), and Meckel's diverticulum (1.3%). Of the 27 patients with documented liver metastases, carcinoid syndrome developed in only 13 patients (48%), manifested by watery diarrhea (100%), upper body flushing (70%), asthma (38%), and tricuspid regurgitation (23%). All 13 patients with carcinoid syndrome had elevated levels of 5-HIAA, but the absolute levels did not correlate with the severity of symptoms. An additional 11 patients, 3 without liver metastases, had elevated levels of 5-HIAA without any evidence of carcinoid syndrome. Multicentric carcinoid tumors occurred in 15 patients (10%), and all but one of these tumors were centered around the ileocecal valve. There was no difference in the incidence of liver metastases between solitary (18%) and multicentric carcinoids (20%). Synchronous noncarcinoid tumors were present in 33 patients (22%), and metachronous tumors developed in an additional 14 patients (10%) in follow-up. Age and tumor size, depth, and location were significant predictors of metastases. By multivariate analysis, age > or = 50 years, metastases, and male gender were statistically significant predictors of death.

CONCLUSIONS

Gastrointestinal tract carcinoid tumors have a nonspecific clinical presentation, except in the case of the carcinoid syndrome. Surgical resection is the treatment of choice for improving survival. Surgically treated patients with carcinoid tumor have an overall favorable 83% 5-year survival rate.

Carcinoid heart disease and carcinoid syndrome: successful surgical treatment

Tumor debulking can greatly improve quality of life for patients with malignant carcinoid syndrome, but hepatic cytoreduction is confounded by carcinoid heart disease, which can cause postsinusoidal portal hypertension, thereby increasing the risk of death from hemorrhage during hepatic resection. We describe a patient with metastatic carcinoid syndrome and carcinoid heart disease who had repair of his carcinoid heart disease and, after improvement of right-sided heart function, had successful hepatic debulking of carcinoid metastases.

The cost-effectiveness of octreotide acetate in the treatment of carcinoid syndrome and VIPoma

Markov modeling was used to evaluate the cost-effectiveness of octreotide in treating carcinoid syndrome and VIPoma. For each condition, using octreotide was associated with doubled survival time. Octreotide was cost-effective for treating carcinoid tumor ($752 per additional year of life, two additional years on average), and cost saving for VIPoma.

Gastrointestinal carcinoid tumors: current management strategies

BACKGROUND

Carcinoid or neuroendocrine tumors of the gastrointestinal tract, although characteristically indolent, are also quite heterogeneous both with respect to histologic and endocrine features and with respect to clinical presentation and behavior.

PURPOSE

This study was undertaken to review and summarize the current literature on classification controversies, site-specific carcinoid presentation and behavior, and diagnostic and management strategies for primary and advanced carcinoid tumors and the carcinoid syndrome.

RESULTS

For carcinoid tumors, oncologic results depend on the location of the primary tumor, extent of locoregional and metastatic disease, functioning status of the tumor, and the feasibility of complete surgical extirpation. Whereas favorable survival rates are typically observed for appendiceal and rectal primaries, less favorable rates are often observed for colonic and ileal tumors. A search for additional tumors is generally advised because multiple carcinoids and second neoplasms are not uncommon. Because of the indolent nature of the tumor and because these therapies have been shown to improve quality and quantity of life, otherwise fit patients with advanced carcinoid disease should be treated with aggressive medical and surgical therapies. Development of a malignant carcinoid syndrome indicates the presence of a functionally active carcinoid tumor and portends a poor prognosis.

CONCLUSION

Gastrointestinal carcinoids, although malignant, behave differently from other carcinomas. Results are highly variable and must be individualized according to the site of the primary tumor, extent of spread, and general condition of the patient. A prolongation of quality life can often be accomplished through aggressive medical and surgical therapies.

Carcinoid tumours

The use of long-acting and potent somatostatin analogues is a major advance in the management of carcinoid tumours. In addition to providing effective symptom relief in malignant carcinoid syndrome, octreotide can also be used for diagnostic purposes. Despite its expense, octreotide is the current agent of choice for the treatment of this condition while analogues with different receptor specificities and pharmacokinetics hold promise for the future. Gastric carcinoids have aroused interest because of their experimental association with chronic hypergastrinaemia, a condition now commonplace because of the widespread use of H2-blockers and proton-pump inhibitors. This subject is reviewed. The slow evolution of many tumours demands prolonged follow-up and the active use of a variety of palliative interventions. These include measures such as hepatic and cardiac surgery, which might be deemed inappropriate for patients with other types of metastatic malignancy. Interferons may have a role when first-line treatments have failed. Chemotherapy is, generally, of limited value.

Somatostatin analogue treatment of neuroendocrine tumours

The long-acting analogues of somatostatin have an established place in the medical treatment of patients with neuroendocrine tumours. They act through binding with specific, high-affinity membrane receptors. Somatostatin analogue therapy is an effective and safe treatment for most growth hormone and thyrothropin-secreting pituitary adenomas. The potential therapeutic consequences of the presence of somatostatin receptors on clinically 'nonfunctioning' pituitary tumours are still uncertain. Somatostatin analogues are not useful in the treatment of patients with prolactinomas, or adrenocorticotropin (ACTH)-secreting adenomas. However, the somatostatin analogue octreotide suppressed pathological ACTH release in some patients with Nelson's syndrome and ACTH and cortisol secretion in several patients with Cushing's syndrome caused by ectopic ACTH secretion. Somatostatin analogues are effective in the sympatomatic treatment of most (metastatic) pancreatic islet cell tumours and most (metastatic) carcinoids. In some of these patients, they also induce tumour stabilisation or reduction. In some patients with (metastatic) medullary thyroid carcinomas, continuous treatment with very high doses of octreotide can be of temporary relief. The clinical effectiveness of somatostatin analogues in patients with small cell lung cancer is currently under investigation. Long-term therapy with somatostatin analogues of catecholamine-secreting (malignant) paragangliomas and phaeochromocytomas has not shown clinical benefits.

Octreotide treatment of carcinoid syndrome: analysis of published dose-titration data

BACKGROUND

Octreotide has proven therapeutically effective in carcinoid syndrome, but the rarity of carcinoid tumors has hampered detailed dose-ranging studies. This study analysed published dose-titration data on octreotide use in carcinoid patients to (a) investigate the relation between octreotide dose and efficacy and (b) establish octreotide dosing recommendations for maximum therapeutic benefit.

METHOD

An exhaustive, computer-assisted literature search for published articles employing octreotide to manage patients with carcinoid syndrome was performed using several databases. The relation between octreotide dose and efficacy in decreasing urinary 5-hydroxyindoleacetic acid (5-HIAA) levels, flushing and diarrhoea was analysed for seven dose ranges by pooling data from selected articles.

RESULTS

Analysis of data compiled from 62 published studies revealed that maximum effective therapeutic doses of octreotide effectively controlled symptoms in up to 93% of patients, and that increasing the dose of octreotide is associated with increased benefit with respect to control of flushing, diarrhoea and 5-HIAA levels.

CONCLUSIONS

We recommend starting octreotide therapy at 100 micrograms subcutaneously t.d.s. in patients with mild/moderate, non-life-threatening carcinoid syndrome. Since therapeutic response to octreotide varies markedly among patients, we recommend titrating the octreotide dose in increments of 50-100 micrograms every 8 h until adequate symptom control is achieved.

Treatment of metastatic carcinoid tumors using multimodality therapy of octreotide acetate, intra-arterial chemotherapy, and hepatic arterial chemoembolization

BACKGROUND

Overall survival and quality of life in patients with metastatic carcinoid tumors depend on control of tumor growth and suppression of amine-induced symptoms.

METHODS

We report on a series of 10 patients with carcinoid tumors metastatic to the liver who were treated with long-term octreotide acetate therapy (100 to 500 micrograms three times a day), sequential intra-arterial 5-fluorouracil (5-FU) infusions, and hepatic tumor chemoembolization.

RESULTS

All 10 patients remained asymptomatic or had extremely mild symptoms after combined modality therapy (mean follow-up duration of 51.5 months). Sixty percent of the patients had a > 50% reduction of their tumor size (mean duration 42 months). An additional 30% experienced stabilization of tumor growth for 6 months or longer. Five of the 10 patients are currently alive. The mean group survival is 58 months since diagnosis (range 33 to 115) and 40 months since starting therapy (range 12 to 65).

CONCLUSIONS

Combining octreotide acetate, intra-arterial 5-FU, and tumor chemoembolization effectively retards tumor growth while providing excellent symptom control.

Radiation therapy in the management of patients with malignant carcinoid tumors

BACKGROUND

The purpose of this study was to analyze the effectiveness of radiotherapy for symptomatic, metastatic, and/or unresectable carcinoid tumors.

METHODS

From 1975 to 1991, 18 patients with histologically proven carcinoid tumors, including 7 with symptomatic hepatic involvement, received radiotherapy to a total of 31 anatomic sites of metastatic or unresectable carcinoid tumors. Symptomatic response to treatment, date of symptomatic or radiographic progression, and survival after diagnosis and completion of radiotherapy were determined. Clinical improvement was defined as symptomatic relief and/or objective reduction in size of tumor mass sustained for at least 4 weeks.

RESULTS

After radiotherapy of 31 sites in 18 patients, 3 patients died in less than 3 months. Of the remaining 15 patients, survival from initial radiotherapy ranged from 8 to 108 months (median, 23 months), and 8 (53%) died without symptomatic progression in the treated region. Clinical improvement occurred in 27/31 sites (87%). Acute side effects were mild, and no late side effects were recorded. Median survivals from diagnosis were: 39 months for patients with primary tumors of the lung, 33 months for patients with brain metastases, and 32 months for patients with hepatic involvement. Patients with the carcinoid syndrome responded in 19/22 sites (86%) compared with 8/9 sites (89%) for patients without the syndrome (P = not significant).

CONCLUSIONS

Radiation therapy can achieve symptomatic palliation for patients with metastatic/unresectable malignant carcinoid tumors, and it is well tolerated. Clinical improvement occurs after irradiation in patients with or without the carcinoid syndrome.