Advancements in medical treatment for pancreatic neuroendocrine tumors: A beacon of hope

This editorial highlights the remarkable advancements in medical treatment strategies for pancreatic neuroendocrine tumors (pan-NETs), emphasizing tailored approaches for specific subtypes. Cytoreductive surgery and somatostatin analogs (SSAs) play pivotal roles in managing tumors, while palliative options such as molecular targeted therapy, peptide receptor radionuclide therapy, and chemotherapy are reserved for SSA-refractory patients. Gastrinomas, insulinomas, glucagonomas, carcinoid tumors and VIPomas necessitate distinct thera-peutic strategies. Understanding the genetic basis of pan-NETs and exploring immunotherapies could lead to promising avenues for future research. This review underscores the evolving landscape of pan-NET treatment, offering renewed hope and improved outcomes for patients facing this complex disease.

Newer parameters of the octreotide test in patients with acromegaly

PURPOSE

Predicting the therapeutic effects of first-generation somatostatin receptor ligands (fg-SRLs) is important when assessing or planning effective treatment strategies in patients with acromegaly. The oft-used maximum growth hormone (GH) suppression rate parameter of the octreotide test has a suboptimal predictive value. Therefore, this study explored newer parameters of the octreotide test for predicting the therapeutic effect of long-acting fg-SRLs.

METHODS

In this single-center retrospective study, the octreotide test parameters and the therapeutic effects of fg-SRL at 3 months were investigated in 45 consecutive treatment-naïve patients with acromegaly between April 2008 and March 2023. Additionally, the relationship between the octreotide test parameters and the therapeutic effects of fg-SRLs was investigated. Tumor shrinkage was evaluated based on changes in the longitudinal diameter of the macroadenomas. The area GH suppression rate-time under the curve (AUC) and the time to nadir GH level were calculated and compared with the maximum GH suppression rate.

RESULTS

The AUC estimated reductions in serum insulin-like growth factor I, and tumor shrinkage. The time to nadir GH level predicted tumor shrinkage more robustly than the maximum GH suppression rate in patients with macroadenoma.

CONCLUSION

The AUC and time to nadir GH level may potentially be newer parameters of the octreotide test for estimating the therapeutic effect of fg-SRLs.

Somatostatin-analog effect on pancreatic fistula after radical gastrectomy: a pilot randomized controlled trial

PURPOSE

Radical gastrectomy with D2 lymphadenectomy can trigger a high incidence of postoperative pancreatic fistula (POPF), which produces a poor clinical prognosis. We sought to evaluate the effect of somatostatin analogs (SSA) on POPF and clinical prognosis after radical gastrectomy.

METHODS

A total of 123 patients with a high risk of POPF after radical gastrectomy (drainage fluid amylase concentration on a postoperative day [POD] 1 > 3 times the upper limit of normal serum amylase value) were randomly divided into the SSA group (n = 61) and the control group (n = 62). The former received continuous intravenous SSA (0.3 mg/8 h) for 3 days from POD1, and the latter normal saline. The primary outcome was the incidence of POPF.

RESULTS

The incidence of POPFs in the SSA group was significantly lower than that in the control group (3.3% vs. 14.5%, P = 0.029). The incidence of short-term postoperative complications was significantly lower in the SSA group than in the control group (9.8% vs. 24.2%, P = 0.034). The median white blood cell counts, neutrophil counts, and the percentage of neutrophils on POD4 were significantly lower in the SSA group than in the control group (all P < 0.05). The SSA group had a shorter mean time to the first liquid diet (87.33 ± 17.92 h vs. 93.97 ± 17.29 h, P = 0.039). And the SSA group had less median daily drainage volume (96.33 mL vs. 119.67 mL, P = 0.025) and shorter drainage duration (7.0 days vs. 10.0 days, P = 0.013).

CONCLUSION

Postoperative treatment with a somatostatin analog reduced the incidence of POPF and short-term complications after radical gastrectomy. (TRN: ChiCTR2200056201, Reg. Date: 2022/2/1).

PRESTO 2: An International Survey to Evaluate Patients' Injection Experiences with the Latest Devices/Formulations of Long-Acting Somatostatin Analog Therapies for Neuroendocrine Tumors or Acromegaly

INTRODUCTION

Real-world data evaluating patients' injection experiences using the latest devices/formulations of the long-acting (LA) somatostatin analogs (SSAs) lanreotide Autogel/Depot (LAN; Somatuline®) and octreotide LA release (OCT; Sandostatin®) are limited.

METHODS

PRESTO 2 was a 2020/2021 e-survey comparing injection experience of adults with neuroendocrine tumors (NETs) or acromegaly treated with LAN prefilled syringe versus OCT syringe for > 3 months in Canada, Ireland, the UK and the USA (planned sample size, 304).

PRIMARY ENDPOINT

the proportion of patients with injection-site pain lasting > 2 days after their most recent injection, analyzed using a multivariate logistic regression model. Secondary endpoints included interference with daily life due to injection-site pain and technical injection problems in patients with current SSA use for ≥ 6 months.

RESULTS

There were 304 respondents (acromegaly, n = 85; NETs, n = 219; LAN, n = 168; OCT, n = 136; 69.2% female; mean age, 59.6 years). Fewer patients had injection-site pain lasting > 2 days after the most recent injection with LAN (6.0%) than OCT (22.8%); the odds of pain lasting > 2 days were significantly lower for LAN than OCT, adjusted for disease subgroup and occurrence of injection-site reactions (odds ratio [95% confidence interval]: 0.13 [0.06-0.30]; p < 0.0001). Injection-site pain interfered with daily life "a little bit" or "quite a bit" in 37.2% and 3.8% (LAN) versus 52.5% and 7.5% (OCT) of patients, respectively. Among patients with ≥ 6 months' experience with current SSA (92.4% of patients), technical injection problems never occurred in 76.8% (LAN) and 42.9% (OCT) of patients.

CONCLUSIONS

Compared with OCT, significantly fewer patients using LAN had injection-site pain lasting > 2 days after their most recent injection. Also, fewer LAN-treated patients experienced technical problems during injection. These findings demonstrate the importance of injection modality for overall LA SSA injection experience for patients with acromegaly or NETs.

Primary testicular neuroendocrine tumor with liver lymph node metastasis: A case report and review of the literature

BACKGROUND

Primary testicular neuroendocrine tumors (TNETs) are sporadic, accounting for only 0.23% of all testicular tumors. Few cases have been reported in the literature, and no uniform treatment protocol exists. We report a case of a primary TNET with liver lymph node metastasis diagnosed at the age of 24 years and discuss its clinicopathological features, diagnosis, differential diagnosis, treatment, and prognosis.

CASE SUMMARY

We report the case of a 24-year-old patient with a primary TNET with liver lymph node metastasis. The patient was found to have a right testicular swelling of about 3 cm × 4 cm in size with unclear borders and no testicular pressure pain seven years ago without any examination or treatment. One month ago, an ultrasound examination was performed for persistent enlargement of the right testis, which showed an occupying lesion of the right testis approximately 110 mm × 102 mm × 82 mm in size. Magnetic resonance imaging scan of the testis (plain scan) showed that the right testis was an occupying lesion with inhomogeneous density and mixed signal, the boundary was still clear, and the possibility of seminoma was considered; chest X-ray and computed tomography did not show any apparent abnormalities. The patient underwent radical orchiectomy, and the pathological examination suggested a right TNET with a typical carcinoid tumor histological type. One month after the surgery, the patient received nine cycles of lanreotide chemotherapy at a dose of 90 mg/mo without adverse effects. No distant lymph node or other organ metastases were detected at follow-up. He is in good physical condition and attends regular follow-up visits.

CONCLUSION

Neuroendocrine tumors are rare in clinical practice, and the diagnosis mainly relies on the characteristics of microscopic tumor cells and immunohistochemical features. Treatment involves radical orchiectomy. If it is accompanied by distant lymph node metastasis and the metastatic lesion can be resected, it should be surgically removed; if it cannot be resected, growth inhibitor analog octreotide or lanreotide chemotherapy can be administered to obtain good results, with close postoperative follow-up to prevent recurrence and metastasis.

External Validity of Somatostatin Analogs Trials in Advanced Neuroendocrine Neoplasms: The GETNE-TRASGU Study

INTRODUCTION

Somatostatin analogs (SSA) prolong progression-free survival (PFS) in patients with well-differentiated gastroenteropancreatic neuroendocrine neoplasms (GEP-NENs). However, the eligibility criteria in randomized clinical trials (RCTs) have been restricted, which contrasts with the vast heterogeneity found in NENs.

METHODS

We identified patients with well-differentiated (Ki-67% ≤20%), metastatic GEP-NENs treated in first line with SSA monotherapy from the Spanish R-GETNE registry. The therapeutic effect was evaluated using a Bayesian Cox model. The objective was to compare survival-based outcomes from real-world clinical practice versus RCTs.

RESULTS

The dataset contained 535 patients with a median age of 62 years (range: 26-89). The median Ki-67% was 4 (range: 0-20). The most common primary tumor sites were as follows: midgut, 46%; pancreas, 34%; unknown primary, 10%; and colorectal, 10%. Half of the patients received octreotide LAR (n = 266) and half, lanreotide autogel (n = 269). The median PFS was 28.0 months (95% CI: 22.1-32.0) for octreotide versus 30.1 months (95% CI: 23.1-38.0) for lanreotide. The overall hazard ratio for lanreotide versus octreotide was 0.90 (95% credible interval: 0.71-1.12). The probability of effect sizes >30% with lanreotide versus octreotide was 2 and 6% for midgut and foregut NENs, respectively.

CONCLUSION

Our study evaluated the external validity of RCTs examining SSAs in the real world, as well as the main effect-modifying factors (progression status, symptoms, tumor site, specific metastases, and analytical data). Our results indicate that both octreotide LAR and lanreotide autogel had a similar effect on PFS. Consequently, both represent valid alternatives in patients with well-differentiated, metastatic GEP-NENs.

Patients' satisfaction with long-acting injectable somatostatin analog therapy for neuroendocrine tumors

BACKGROUND

Long-acting somatostatin analogs (LA SSAs) are approved and recommended for the treatment of patients with advanced neuroendocrine tumors (NETs). Given the long duration of therapy and differences in administration routes, it is important to understand patients' experiences with receiving LA SSA injections.

METHODS

We conducted a serial survey, informed by qualitative interviews with eight patients treated with LA SSAs and two nurses who administer LA SSA injections, among patients undergoing LA SSA treatment over a 28-day period (administered at baseline and 14 days and 28 days after injection). Eligible patients, recruited by the Carcinoid Cancer Foundation, self-reported having received an LA SSA injection for physician-diagnosed NET within the 5 days before the survey.

RESULTS

202 patients completed the survey at baseline (82 receiving lanreotide and 120 receiving octreotide), 148 at day 14, and 124 at day 28. Patients reported consistently high satisfaction levels with their most recent LA SSA injection (91.1% at baseline, 85.1% at day 14, and 85.5% at day 28); 68.8% reported that their injection experience differed based on the nursing staff administering the injection.

CONCLUSIONS

Satisfaction with LA SSA injections is high among patients in this population, and specific experiences with LA SSA injections varied based on the nursing staff administering the injection. Evaluations of patients' experiences and satisfaction with treatment are increasingly important as patients take more active roles in decision-making for their treatment pathways.

Preoperative and long-term efficacy and safety of lanreotide autogel in patients with thyrotropin-secreting pituitary adenoma: a multicenter, single-arm, phase 3 study in Japan

Somatostatin analogs are recommended for pharmacotherapy of TSH-secreting pituitary adenoma (TSHoma). A multicenter clinical trial was conducted to evaluate the efficacy and safety of lanreotide autogel treatment for TSHoma. A total of 13 Japanese patients with TSHoma were enrolled from February to December 2018 and treated with lanreotide autogel 90 mg every 4 weeks, with dose adjustments to 60 mg or 120 mg. Analysis was performed on data from patients receiving preoperative treatment (n = 6) up to 24 weeks and from those receiving primary or postoperative treatment (n = 7) up to 52 weeks. The primary efficacy endpoints were serum concentrations of TSH, free triiodothyronine (FT3), and free thyroxine (FT4). The secondary efficacy endpoints were pituitary tumor size and clinical symptoms. The serum concentrations of TSH, FT3, and FT4 decreased with treatment, and euthyroid status was maintained until final assessment. FT4 at final assessment was within reference ranges in 10/13 patients. The median (interquartile range) percent change in pituitary tumor size from baseline at final assessment was -23.8% (-38.1, -19.8). The clinical symptoms were also improved. The patients receiving preoperative treatment did not develop perioperative thyroid storm. Regarding safety, adverse events were observed in 12/13 patients, but none discontinued treatment. The common adverse events were gastrointestinal disorders (12/13 patients) and administration site reactions (5/13 patients). Lanreotide autogel may be effective for controlling thyroid function and reducing the pituitary tumor size, and is tolerable in patients with TSHoma (Japic Clinical Trials Information; JapicCTI-173772).

The effect of somatostatin analogs and acromegaly on the upper gastrointestinal system

PURPOSE

To evaluate the effects of somatostatin analogs and disease activity status on the upper gastrointestinal system in patients with acromegaly.

METHODS

One hundred eighty-one patients with acromegaly were retrospectively assessed. The demographic, biochemical, pathologic, and radiologic data of the patients were evaluated. The upper gastrointestinal endoscopies and endoscopic biopsies were investigated. We divided patients into four groups according to the use of somatostatin analogs, and into two groups according to disease activity. We compared the data of patients between groups A, B, C, and D, and controlled/uncontrolled groups separately.

RESULTS

Before and in the peri-endoscopic period, 67 and 27 patients were being treated with octreotide long-acting release (LAR) (group A) and lanreotide autogel (group B), respectively. Twenty-one patients used somatostatin analogs, but they were stopped for various reasons before upper gastrointestinal endoscopy (group C), and 66 patients did not use a somatostatin analog (group D). In the peri-endoscopic period, 103 (60%) patients were responsive to medical and/or surgical treatment and 67 (40%) patients were non-responsive. The rate of gastritis was higher in group A than in groups B and D. The incidence of duodenitis and gastric ulcer was much higher in group D. The rate of gastritis was higher in the controlled group compared to the uncontrolled group.

CONCLUSION

The study showed that octreotide LAR treatment could be a risk factor in addition to known factors for the development of gastritis in patients with acromegaly.

Rapid response of Nelson's syndrome to pasireotide in radiotherapy-naive patient

BACKGROUND

Nelson's syndrome is a well-described complication following bilateral adrenalectomy for management of Cushing's disease. There is no consensus on optimal management of Nelson's syndrome, characterized by the triad of pituitary corticotroph adenoma growth, elevated serum adrenocorticotropic hormone, and skin hyperpigmentation. Medical therapy with a variety of drug classes have been studied. One potentially promising drug already approved for Cushing's disease is pasireotide, a somatostatin analog with affinity for multiple somatostatin receptors, including subtype 5, the most highly expressed receptor on corticotroph tumors.

CASE PRESENTATION

A 24-year-old female was diagnosed with Cushing's disease with initial ACTH levels around 700-800 pg/mL. She underwent transsphenoidal surgery without remission, followed by bilateral adrenalectomy. Over the subsequent 3 years, the patient developed skin hyperpigmentation, recurrent elevations of ACTH, and tumor recurrence requiring two additional transsphenoidal surgeries. After her third transsphenoidal resection, ACTH normalized, no residual tumor was seen on radiology, and the patient's skin hyperpigmentation improved. She then had an uncomplicated full-term pregnancy, during which ACTH levels remained within normal limits. One month after delivery, ACTH levels began rising to a peak at 5,935 pg/mL. Imaging revealed two new bilateral pituitary adenomas, measuring 14 mm on the left, and 7 mm on the right. She was then started on pasireotide. After two months of therapy, ACTH decreased to 609 pg/mL, and repeat pituitary MRI showed interval decrease in size of both pituitary adenomas to 13 mm on the left and 6 mm on the right.

CONCLUSION

We report the protracted course of a young female with several recurrences of Nelson's syndrome following bilateral adrenalectomy and multiple transsphenoidal surgeries, who ultimately responded to pasireotide. Unique features of her case not described previously are the response to pasireotide in a radiotherapy-naive patient, as well as the rapid radiologic response to therapy. Her history illustrates the unresolved challenges of Nelson's syndrome and the continued need for additional studies to identify optimal management.

HSP90 expression and early recurrence in gastroenteropancreatic neuroendocrine tumors: Potential for a novel therapeutic target

BACKGROUND

Heat shock protein (HSP)-90 promotes tumor growth and is overexpressed in many malignancies. HSP90 expression profile and its potential as a therapeutic target in primary and metastatic neuroendocrine tumors (NETs) are not known.

METHODS

HSP90 cytoplasmic expression and Ki-67 index were re-reviewed and scored by a pathologist blinded to all other clinicopathologic variables for patients who underwent resection of primary and metastatic gastroenteropancreatic (GEP) neuroendocrine tumors at a single institution (2000-2013). Primary outcome was recurrence-free survival (RFS).

RESULTS

Of 263 tumors reviewed, 73% (n = 191) were primary GEP NETs, and 12% (n = 31) were NET liver metastases. Of the primary GEP-NETs, mean age was 56 years, 42% were male; 53% (n = 103) were pancreatic and 23% (n = 44) were small bowel. HSP90 expression was high in 34% (n = 64) and low in 66% (n = 127). Compared to low expression, high HSP90 was associated with advanced T-stage (T3/T4) (47 vs 27%; p = 0.02). Among patients who underwent curative-intent resections for primary, non-metastatic NETs (n = 145), high HSP90 was independently associated with worse RFS (HR 5.09, 95% CI 1.65-15.74; p = 0.005), after accounting for positive margin, LN involvement, increased tumor size, site of primary tumor, and Ki-67. When assessing NET liver metastases, 13% (n = 4) had high HSP90 expression and 87% (n = 26) had low expression. Patients with liver metastases with high HSP90 tended to have worse 1- and 3-year progression-free survival (25%, 25%) compared to those with low HSP90 (69%, 49%; p = 0.059).

CONCLUSION

HSP90 exhibits differential expression in resected GEP-NETs and liver metastases. High cytoplasmic expression is associated with early disease recurrence, even after accounting for other adverse pathologic factors. HSP90 inhibition may be a potential therapeutic target for neuroendocrine tumors.

Octreotide in the treatment of malignant thymoma - Case report

Thymomas are the most common mediastinal tumors. Systemic therapy for patients with unresectable or recurrent thymomas is a challenging field in the current oncology research. There is some evidence that somatostatin analogs combined with corticosteroids may have a role in the treatment of advanced malignant thymoma; however, the role of these agents have not been fully evaluated.

Case report

A 39-year-old man with metastatic thymoma was administered long-acting depot injection form of octreotide. Octreotide scan before the treatment initiation revealed low uptake. CT control after three months of the treatment revealed marked regression of pleural metastases, while the primary tumor mass remained stable. The treatment response was lasting for 9 months.

Conclusion

We describe an interesting case of marked clinical and radiological response of advanced malignant thymoma to the treatment with octreotide in a heavily pre-treated patient, even though octreotide scan revealed low uptake.

First Case of Regression of Carcinoid Heart Disease on Serial Transthoracic Echocardiograms following Octreotide Monotherapy in a Patient with Metastatic Pancreatic Neuroendocrine Tumor

Well-differentiated neuroendocrine tumors (NETs) arising in the gastrointestinal (GI) tract and pancreas are relatively rare; however, the annual incidence has been increasing. Carcinoid syndrome (CS) is a constellation of symptoms that occur when a GI NET metastasizes to the liver and releases high levels of vasoactive substances into the systemic circulation. CS occurs in 19% of NETs patients at diagnosis and is associated with shorter survival. Carcinoid heart disease (CHD) occurs in over 50% of patients with CS and is associated with poor long-term prognosis. NET-induced valvular fibrosis is a significant cause of mortality and morbidity in these patients. Somatostatin analogs relieve CS symptoms, but they have never been shown to reverse CHD progression or improve overall survival. Surgical therapy for right-sided valve disease is associated with improved symptoms and quality of life and possibly improved survival, despite relatively high morbidity and mortality associated with cardiac intervention. A 65-year-old woman with a metastatic pancreatic NET had typical signs and symptoms of CS. She presented in congestive heart failure and was found to have severe tricuspid regurgitation with characteristic features of CHD on transthoracic echocardiogram (TTE). Following octreotide monotherapy, serial TTEs demonstrated regression of tricuspid valve involvement. The patient improved clinically and remained asymptomatic on subsequent visits. This is the first case of CHD regression with medical therapy supported by serial TTEs. Developing a deeper understanding of cases like this will help us unlock new intervention targets and strategies for treatments in the future.

Occurrence of exocrine pancreatic insufficiency in patients with advanced neuroendocrine tumors treated with somatostatin analogs

BACKGROUND

Although exocrine pancreatic insufficiency (EPI) has been described in patients with neuroendocrine neoplasia (NEN) treated with somatostatin analogs (SSAs), its role in the therapeutic management of these patients is not well established.

AIM

To determine the frequency of EPI in patients with NEN long-term treated with SSAs.

METHODS

This is a prospective single-center study evaluating 35 patients treated with SSAs for >12 months due to unresectable/advanced nonpancreatic well-differentiated NEN. Clinical evaluation, biochemical parameters, and fecal elastases 1 (FE-1) were assessed to diagnose EPI.

RESULTS

A total of 7 patients (20%) had EPI, given the presence of abdominal symptoms and a median FE-1 value of 180 mcg/g stool (150-198). No patient had severe EPI, defined as FE-1 < 100 mcg/g stool. Elevated glycated Hb levels were a significant predictor for developing EPI (OR 4.81, p = 0.01). No significant difference in terms of duration of SSA treatment was observed between patients with or without EPI diagnosed (84 months and 72 months, respectively; p = 0.950).

CONCLUSIONS

Mild-moderate EPI is a relatively common condition in patients receiving long-term treatment with SSAs. Specific clinical and biochemical evaluations, including FE-1, should be planned in these patients to diagnose this relevant condition early, which may deteriorate quality of life and cause malnutrition.

Treatment Outcomes in Patients with Metastatic Neuroendocrine Tumors: a Retrospective Analysis of a Community Oncology Database

Purpose

Metastatic neuroendocrine tumors (mNETs) are rare, heterogeneous tumors that present diagnostic and treatment challenges, with limited data on the management of mNETs in clinical practice. The present study was designed to identify current diagnostic and treatment patterns in mNET patients treated in the US community oncology setting.

Methods

Patient-level data was collected from medical records of adults with mNETs from the Vector Oncology Data Warehouse, a comprehensive US community oncology network database.

Results

Of the 263 patients included (median follow-up, 22 months; range, 0.1–193.9), 30.4% (80/263) had intestinal tumors, 11.0% (29/263) had pancreatic, and 58.6% (154/263) had tumors of other or unknown location. Progression-free survival (PFS) from the start of first-line therapy differed significantly by tumor grade (log rank P = 0.0016) and location (P = 0.0044), as did overall survival (OS) (grade, P < 0.0001; location, P = 0.0068). Median PFS and OS for patients with undocumented tumor grade were shorter than for patients with G1/G2 tumors and longer than patients with G3 tumors. Median PFS and OS for patients with other or unknown tumors were shorter than for patients with intestinal tumors.

Conclusions

While potentially confounded by the high number of patients with other or unknown tumor locations, this retrospective study of patients in a US community oncology setting identified the importance of awareness of tumor grade and tumor location at diagnosis, as these were direct correlates of PFS and OS.

Somatostatin Analogs in Clinical Practice: a Review

Somatostatin analogs are an invaluable therapeutic option in the diagnosis and treatment of somatotropinomas, thyrotropinomas, and functioning and non-functioning gastroenteropancreatic neuroendocrine tumors. They should also be considered an effective and safe therapeutic alternative to corticotropinomas, gonadotropinomas, and prolactinomas resistant to dopamine agonists. Somatostatin analogs have also shown to be useful in the treatment of other endocrine diseases (congenital hyperinsulinism, Graves’ orbitopathy, diabetic retinopathy, diabetic macular edema), non-endocrine tumors (breast, colon, prostate, lung, and hepatocellular), and digestive diseases (chronic refractory diarrhea, hepatorenal polycystosis, gastrointestinal hemorrhage, dumping syndrome, and intestinal fistula).

Role of 68Ga-DOTATATE PET/CT in a Case of SDHB-Related Pterygopalatine Fossa Paraganglioma Successfully Controlled with Octreotide

We describe an unusual case of a 42-year-old female with an unresectable succinate dehydrogenase subunit B (SDHB)-related pterygopalatine fossa paraganglioma. She underwent somatostatin receptor imaging with ⁶⁸Ga-DOTA(0)-Tyr(3)-octreotate (⁶⁸Ga-DOTATATE) positron emission tomography/computed tomography (PET/CT), which showed uptake in the above mentioned tumor. Hence, the patient was started on octreotide, a cold somatostatin analog, and responded with tumor stabilization and improvement of clinical symptoms for 36 months since initiation of octreotide therapy. This case demonstrates the role of ⁶⁸Ga-DOTATATE PET/CT in diagnostic localization and its subsequent role in treatment using cold somatostatin analog as a potential choice of therapy in the management of paraganglioma in an unusual location with limited therapeutic options.

Long-Term Effects of Intracapsular Debulking and Adjuvant Somatostatin Analogs for Growth Hormone-Secreting Pituitary Macroadenoma: 10 Years of Experience in a Single Institute

OBJECTIVE

Long-term effects of endoscopic endonasal transsphenoidal intracapsular debulking and adjuvant somatostatin analogs (SSAs) were evaluated in patients with growth hormone- (GH) secreting pituitary macroadenomas.

METHODS

We retrospectively reviewed the medical records of 45 patients with acromegalic macroadenoma who underwent endonasal endoscopic transsphenoidal intracapsular debulking and received adjuvant SSAs (octreotide) between 2006 and 2015 who had >1 year of follow-up. To evaluate the predictive factors for 1 year and long-term biochemical outcomes, univariate and multivariate analyses were performed.

RESULTS

Biochemical remission was achieved in 1 year in 20 of the 45 (44.4%) patients, and in 31 of the 45 patients after long-term adjuvant SSA treatment. Tumor control was achieved in 43 of the 45 (93.3%) patients. The univariate analysis showed age (≥55 years), tumor size (diameter ≤1.5 cm), premedication GH levels (≤2.8 ng/mL), premedication insulin-like growth factor 1 levels (≤2-fold of upper limit of normal range), cavernous sinus invasion (Knops grades 2, 3, and 4), and near-total tumor resection were associated with long-term outcomes. The multivariate analysis showed near-total resection was a significant predictor for long-term outcomes (P = 0.019). There were no new pituitary dysfunctions. The observed complications included one case of cerebrospinal fluid leakage and one case of epistaxis requiring intervention.

CONCLUSIONS

Intracapsular debulking and adjuvant SSAs are a safe and viable treatment for patients with GH secreting pituitary macroadenoma to achieve biochemical remission and tumor control. Although adjuvant SSA treatment enhances residual tumor control, cavernous sinus invasion impedes the remission of endocrine tumors.

Pancreatic VIPomas from China: Case reports and literature review

Vasoactive intestinal polypeptide-secreting tumors (VIPomas) are rare neuroendocrine tumors that often present as watery diarrhea, hypokalemia, and achlorhydria or hypochlorhydria. In this study, we present our institutional experience of diagnosis and treatment of VIPomas, along with a review of the Chinese literature since 1980. Patient #1, diagnosed in 1984 and with intact clinical records, shows the natural history of this disease. Patient #2, diagnosed in 2015, shows the results of evaluation by nuclear medicine techniques and the outcomes of standardized treatment. Comprehensive review of 41 cases allows evaluation of clinical characteristics, treatments and outcomes of pancreatic VIPoma patients. All patients presented with watery diarrhea. The average stool volume reached 3247 mL per day. Average serum VIP level was 839.3 ng/L. Twelve of the 41 cases were reported to have metastases at diagnosis. Somatostatin receptor scintigraphy and ¹⁸FDG PET-CT are efficient methods for detection of VIPoma. Surgical excision can promptly alleviate hormonal symptoms.

Clinical outcomes of patients with G1/G2 neuroendocrine tumors arising from foregut or hindgut treated with somatostatin analogs: a retrospective study

Neuroendocrine tumors (NET) are rare tumors for which somatostatin analogs (SSA) are used not only for symptom control due to a functioning tumor, but also for the disease control of unresectable NET. The efficacy of SSA for midgut NET has been verified by previous studies, but insufficient evidence exists for SSA treatment of NET in the foregut and hindgut (F/H-NET). The aim of this retrospective study was to evaluate the efficacy of SSA for unresectable F/H-NET. Patients with unresectable F/H-NET treated with SSA between February 2011 and August 2017 at our hospital were retrospectively reviewed. Parameters of efficacy were progression-free survival (PFS), overall survival, objective response rate (ORR), and adverse events. Twelve cases with unresectable F/H-NET were extracted from our database. With a median follow-up time of 25.9 months, the median PFS was 13.6 months. Two- and 3-year survival rates were 87.5 and 62.5%, respectively. The ORR was 8.3%, and the disease control rate was 75%. Serious adverse events were not observed. Subgroup analysis, including G1/G2, and hepatic tumor load, which is the volume of NET liver metastases, did not reveal a difference in PFS. The efficacy and safety of SSA for F/H-NET seemed similar to that found in the PROMID study, highlighting its relevance for the treatment of this disease.

Oral Ondansetron Offers Effective Antidiarrheal Activity for Carcinoid Syndrome Refractory to Somatostatin Analogs

OBJECTIVES

Somatostatin analogs (SSAs) are standard for symptomatic patients with neuroendocrine tumors (NETs). However, most patients experience tachyphylaxis, and limited options exist for this so-called "refractory carcinoid syndrome." Recently, 5-HT₃ antagonist ondansetron has been associated with reduction of bowel movement in a small series. The aim of this analysis was to assess effectiveness of ondansetron for symptomatic treatment of carcinoid syndrome.

DESIGN AND PATIENTS

We have analyzed patients given ondansetron as bridging therapy for refractory carcinoid syndrome. The dose was 2 × 8 mg for 5 days, followed by reduction to 1 × 8 mg in case of benefit.

RESULTS

A total of 14 patients with small bowel NETs metastatic to the liver were identified. All patients had been treated with SSAs for a median time of 18 months before aggravation of diarrhea. One patient had to be excluded because of an underlying infectious cause of diarrhea. The median number of daily bowel movements was 7 (range, 5-13) before initiation of therapy. At this time, seven patients had stable disease, whereas six patients showed radiological progression with symptomatic breakthrough. All 13 patients were scheduled for salvage therapy. Remarkably, in 85% (11/13) ondansetron resulted in a clinically relevant decrease of bowel movements to a median of 3 (1-4). The median time of ondansetron intake was 29 days (7 days to 29 months). In four patients, diarrhea recurred after initial improvement at an interval of 22-43 days, whereas the remaining seven had an ongoing benefit, including two long-term responders who refused further therapy because of pronounced decrease of symptoms (ondansetron for 14+ and 29+ months).

CONCLUSION

Ondansetron offers symptomatic relief in the majority of patients. Although there was no influence on 5-HIAA levels, evidence from two patients suggests prolonged benefit.

IMPLICATIONS FOR PRACTICE

Somatostatin analogs are standard treatment in patients with carcinoid syndrome and have an overall response rate of up to 50%. This symptomatic benefit, however, is lost in many patients because of the development of tachyphylaxis or tumor progression. Patients with this "refractory carcinoid syndrome" pose a therapeutic challenge and are sometimes faced with a detrimental effect on quality of life. In this article, the authors suggest the 5-HT₃ receptor antagonist ondansetron as potential symptomatic therapy for patients with refractory diarrhea due to carcinoid syndrome. Although the number of patients in this retrospective series is limited, treatment was easily applicable, feasible, and safe and resulted in an ongoing symptomatic benefit in 85% of patients, including two long-term responders.

Commentary on "Co-Occurrence of Pituitary Adenoma With Suprasellar and Olfactory Groove Meningiomas"

Recently, Basic and Clinical Neuroscience published an article by Lim et al. (2016) entitled Co-occurence of Pituitary Adenoma with Suprasellar and Olfactory Groove Meningiomas. They claimed it as the first case of co-occurence of these two malignancies. However, to our knowledge, this is not the first case reported in this regard. We reported the same case scenario in a 61-year-old woman referred to our outpatient clinic in 2007. In this commentary, we are going to discuss our reported case and present a brief review over co-occurence of intracranial meningioma with pituitary adenoma.

Effect of AP102, a subtype 2 and 5 specific somatostatin analog, on glucose metabolism in rats

PURPOSE

Somatostatin analogs are widely used to treat conditions associated with hormonal hypersecretion such as acromegaly and metastatic neuroendocrine tumors. First generation somatostatin analogs, such as octreotide and lanreotide, have high affinity for somatostatin receptor subtype 2 (SSTR2), but have incomplete efficacy in many patients. Pasireotide targets multiple SSTRs, having the highest affinity for SSTR5, but causes hyperglycemia and diabetes mellitus in preclinical and clinical studies. AP102 is a new somatostatin analogs with high affinity at both SSTR2 and SSTR5. We aimed to characterize the effects of AP102 vs. pasireotide on random and dynamic glucose levels, glucoregulatory hormone concentrations and growth axis measures in healthy Sprague-Dawley rats.

METHODS

Three doses of each compound were evaluated under acute conditions (1, 10, and 30 µg/kg s.c.), and two doses during a chronic (4-week) infusion (3 and 10 µg/kg/h s.c.).

RESULTS

Neither acute nor chronic AP102 administration altered blood glucose concentrations or dynamic responses following an intraperitoneal glucose tolerance test. In contrast, acute and chronic pasireotide dosing increased random and post-intraperitoneal glucose tolerance test blood glucose measures, compared to vehicle-treated controls. Both AP102 and pasireotide acutely suppressed growth hormone levels, although insulin-like growth factor-1 and somatic growth was suppressed to a greater extent with pasireotide.

CONCLUSIONS

AP102 is a new dual SSTR2/SSTR5-specific somatostatin analog that acutely reduces growth hormone but does not cause hyperglycemia during acute or chronic administration in a healthy rat model. Further studies in diabetic animals and in humans are necessary to determine the potential utility of AP102 in the clinical setting.

Biochemical assessment of disease control in acromegaly: reappraisal of the glucose suppression test in somatostatin analogue (SA) treated patients

BACKGROUND

It is recommended not to measure growth hormone during oral glucose suppression (oral glucose tolerance test) during somatostatin analog treatment in acromegaly. However, we have observed that failure to suppress growth hormone in response to oral glucose tolerance test during somatostatin analog unmasks insufficient disease control and hypothesize that somatostatin analog also induces insufficient growth hormone suppression to mixed meals.

METHODS

We therefore compared serum growth hormone levels during two mixed meals in patients with controlled insulin-like growth factor-I levels after either surgery alone (n = 9) or somatostatin analog treatment (n = 9). The patients were unbiasedly matched for gender and insulin-like growth factor-I and studied twice in the following order: (1) during a 6 h growth hormone day curve including two mixed meals and (2) during a 3 h growth hormone profile including 60 min fasting followed by a 2-h oral glucose tolerance test.

RESULTS

During the day curve growth hormone levels were elevated in the somatostatin analog group (P = 0.008) and growth hormone levels 1 h after each meal declined significantly only in the surgery group (P = 0.02). During the oral glucose tolerance test the two groups had similar growth hormone levels prior to the glucose load (P = 0.6), whereas a significant 66% suppression was observed after glucose only in the surgery group (P = 0.001).

CONCLUSIONS

(1) Patients controlled by somatostatin analog fail to suppress growth hormone in response to both mixed meals and oral glucose tolerance test (2) This phenomenon is likely to result in elevated serum growth hormone levels during everyday life in somatostatin analog-treated patients, (3) We postulate that measuring growth hormone levels during oral glucose tolerance test is useful to unmask potential somatostatin analog under-treatment in the presence of 'safe' insulin-like growth factor-I levels.

Phase II study of lanreotide autogel in Japanese patients with unresectable or metastatic well-differentiated neuroendocrine tumors

Background Lanreotide is a long-acting somatostatin analog with demonstrated efficacy against enteropancreatic neuroendocrine tumor (NET) in the phase III (CLARINET) study. Materials and Methods In this single-arm study, Japanese patients with grade (G) 1/G2 NET received lanreotide (120 mg/4 weeks) for 48 weeks. Those who completed the study were enrolled in a long-term extension study. The primary endpoint was the clinical benefit rate (CBR) defined as a complete response, partial response (PR), or stable disease (SD) over 24-weeks. Secondary endpoints included progression-free survival (PFS), objective response rate (ORR), safety, and pharmacokinetics. Results Thirty-two patients were recruited at 10 sites. The full analysis set (FAS) comprised 28 patients. Primary tumors were located in pancreas (12 patients), foregut (non-pancreas, lung; 1), midgut (2), hindgut (8), and unknown (5). Four patients had gastrinoma of the functional NET, and 3 had multiple endocrine neoplasia type 1. In the FAS, 39.3% had progressive disease at baseline. The CBR at 24 weeks was 64.3% (95% confidence interval; CI: 44.1–81.4), and median PFS was 36.3 weeks (95% CI: 24.1–53.1). PR was confirmed in 1 patient at 60 weeks during the extension study (ORR: 3.6%). Frequent adverse events related to lanreotide included injection site induration (28.1%), faeces pale (18.8%), flatulence (12.5%), and diabetes mellitus (12.5%). Conclusions The efficacy and safety of lanreotide in this study indicated its usefulness as a treatment option for Japanese NET patients. Trial registration: JapicCTI-132,375, JapicCTI-142,698.

Treatment adherence and persistence with long-acting somatostatin analog therapy for the treatment of acromegaly: a retrospective analysis

Background

Many patients with acromegaly require medical treatment that includes somatostatin analogs (SSAs). Long-acting SSA formulations are widely used, due in part to increased patient convenience and increased treatment adherence vs daily medications. Although medication compliance can be poor in patients with chronic conditions, adherence and persistence with these SSAs in patients with acromegaly has not been evaluated. This analysis utilized claims data to estimate treatment adherence and persistence for lanreotide depot and long-acting octreotide in this population.

Methods

This retrospective analysis used the MarketScan® database (~100 payors, 500 million claims in the US), which was searched between January 2007 and June 2012 to identify patients with acromegaly taking either lanreotide depot or long-acting octreotide. Patients switching treatments were excluded. Treatment adherence was assessed using medication possession ratio (MPR; number of doses dispensed in relation to dispensing period; ≥80% is considered adherent), injection count, and treatment time. Persistence was estimated by Kaplan-Meier analyses and Cox proportional hazards modeling. A washout period, defined as no acromegaly-related prescription activity 180 days prior to the index date, was employed to minimize effects of prior therapy and focus on patients more likely to be treatment-naïve.

Results

Altogether 1308 patients with acromegaly receiving a single SSA for treatment (1127 octreotide, 181 lanreotide) who had not switched treatments were identified. Mean MPR in patients with a 180-day washout (n = 663) was 89% for those receiving octreotide (n = 545) and 87% for those receiving lanreotide (n = 118). Median number of days on therapy was 169 (95% CI 135–232) for octreotide patients and 400 (95% CI 232–532) for lanreotide patients. The point estimate of the Cox proportional hazard ratio for stopping treatment was 1.385 for octreotide vs lanreotide (95% CI 1.079–1.777), suggesting a 38.5% increased risk for stopping octreotide before lanreotide.

Conclusions

Treatment adherence was similarly good for both injectable SSA treatments studied, at 87% or greater. Persistence was greater with lanreotide than octreotide and the risk of discontinuing therapy was lower with lanreotide than octreotide. Further studies to determine factors leading to these differences in persistence or to predict discontinuation of therapy may aid in clinical management of these patients.

Loss of Efficacy of Pasireotide After its Re-Administration: is There a Reason Why?

Pasireotide is a recently approved medical treatment for persistent or recurrent Cushing’s disease (CD). However, an escape from the initial successful response has not yet been described. A 42-year-old female presented with several symptoms indicative of hypercortisolism. Biochemical evaluation and imaging were consistent with CD due to a pituitary adenoma. Surgical excision of the adenoma was unsuccessful and gamma-knife radiosurgery was followed. Our patient remained hypercortisolemic thus treatment with pasireotide (900 mg subcutaneously twice daily) was decided. Biochemical and clinical remission was noted shortly thereafter. Moderate adverse events led to dose reduction to 600 mg subcutaneously twice daily. The patient remained in remission for 6 months, when treatment was discontinued due to cholecystitis. One month after cholecystectomy, pasireotide was restarted with no clinical or biochemical benefit that time. Pasireotide is an effective medical treatment for CD. Nevertheless, a loss of its initial efficacy may rarely be described.

Predictive value of T2 relative signal intensity for response to somatostatin analogs in newly diagnosed acromegaly

INTRODUCTION

The difficulty of predicting the efficacy of somatostatin analogs (SSA) is not fully resolved. Here, we quantitatively evaluated the predictive value of relative signal intensity (rSI) on T1- and T2-weighted magnetic resonance imaging (MRI) for the short-term efficacy (3 months) of SSA therapy in patients with active acromegaly and assessed the correlation between MRI rSI and expression of somatostatin receptors (SSTR).

METHODS

This was a retrospective review of prospectively recorded data. Ninety-two newly diagnosed patients (37 males and 55 females) with active acromegaly were recruited. All patients were treated with pre-surgical SSA, followed by reassessment and transspenoidal surgery. rSI values were generated by calculating the ratio of SI in the tumor to the SI of normal frontal white matter. The Youden indices were calculated to determine the optimal cutoff of rSI to determine the efficacy of SSA. The correlation between rSI and expression of SSTR2/5 was analyzed by the Spearman rank correlation coefficient.

RESULTS

T2 rSI was strongly correlated with biochemical sensitivity to SSA. The cutoff value of T2 rSI to distinguish biochemical sensitivity was 1.205, with a positive predictive value (PPV) of 81.5 % and a negative predictive value (NPV) of 77.3 %. No correlation was found between MRI and tumor size sensitivity. Moreover, T2 rSI was negatively correlated with the expression of SSTR5.

CONCLUSION

T2 rSI correlates with the expression of SSTR5 and quantitatively predicts the biochemical efficacy of SSA in acromegaly.

Quantitative analyses of T2-weighted MRI as a potential marker for response to somatostatin analogs in newly diagnosed acromegaly

In growth hormone (GH)-producing adenomas, T2-weighted MRI signal intensity is a marker for granulation pattern and response to somatostatin analogs (SSA). Prediction of treatment response is necessary for individualized treatment, and T2 intensity assessment might improve preoperative classification of somatotropinomas. The objectives of this study are (I) to explore the feasibility of quantitative T2-weighted MRI histogram analyses in newly diagnosed somatotroph adenomas and their relation to clinical and histological parameters and (II) to compare the quantitative method to conventional, visual assessment of T2 intensity. The study was a retrospective cohort study of 58 newly diagnosed patients. In 34 of these, response to primary SSA treatment after median 6 months was evaluated. Parameters from the T2 histogram analyses (T2 intensity ratio and T2 homogeneity ratio) were correlated to visually assessed T2 intensity (hypo-, iso-, hyperintense), baseline characteristics, response to SSA treatment, and histological granulation pattern (anti-Cam5.2). T2 intensity ratio was lowest in the hypointense tumors and highest in the hyperintense tumors (0.66 ± 0.10 vs. 1.07 ± 0.11; p < 0.001). T2 intensity at baseline correlated with reduction in GH (r = -0.67; p < 0.001) and IGF-1 (r = -0.36; p = 0.037) after primary SSA treatment (n = 34). The T2 homogeneity ratio correlated with adenoma size reduction (r = -0.45; p = 0.008). Sparsely granulated adenomas had a higher T2 intensity than densely or intermediately granulated adenomas. T2 histogram analyses are an applicable tool to assess T2 intensity in somatotroph adenomas. Quantitatively assessed T2 intensity ratio in GH-producing adenomas correlates with conventional assessment of T2 intensity, baseline characteristics, response to SSA treatment, and histological granulation pattern.

Expression of somatostatin receptor subtype 2 in growth hormone-secreting pituitary adenoma and the regulation of miR-185

INTRODUCTION

Long-acting somatostatin analogs (SSAs) are most widely used to treat growth hormone (GH)-secreting pituitary adenoma. However, approximately 30 % of treated patients show resistance to SSAs, which may be associated with the reduction of somatostatin receptor subtype 2 (SSTR2) mRNA and protein expression.

MATERIALS AND METHODS

The present study used immunohistochemistry to detect the expression of SSTR2 and SSTR5 in twenty human GH-secreting adenoma samples treated with SSAs and seven normal pituitary samples.

RESULTS

The staining intensities of SSTR2 and SSTR5 were stronger in most adenoma samples than in normal pituitary. The expression of SSTR2 tended to be lower in the SSA non-responder group than in responders. A search of the Bioinformatics data bank and the miRCURY™ LNA array confirmed miR-185 as the putative mircoRNA (miRNA) regulating the expression of SSTR2. An in vitro study using Dual Luciferase reporter assay demonstrated that miR-185 likely targets the 3'-UTR of SSTR2 mRNA in the rat pituitary adenoma GH3 cell line. MiR-185 also downregulated or upregulated the expression of SSTR2 mRNA and SSTR2 protein, following transfection with miR-185 mimics or inhibitors, respectively.

CONCLUSION

MiR-185 enhanced the cell proliferation and inhibited the apoptosis of GH3 cells.

Biotherapy of pancreatic neuroendocrine tumors using somatostatin analogs

Basically, pancreatic neuroendocrine tumor (PNET) should be treated surgically; however, in unresectable cases, a treatment that aims to improve the prognosis by inhibiting the growth of the tumor and control the clinical symptoms becomes necessary. In the case of functional tumors, the quality of life of patients is decreased by not only the symptoms with tumor invasion and/or metastasis but also by the symptoms of hormone excess. The efficacy of somatostatin analogs against the latter has been previously reported, and their sustained release formulations have been developed. Somatostatin analogs are recommended to treat the endocrine symptoms of functional PNET; however, in case they can cause hypoglycemia in patients with insulinoma. On the other hand, results from the PROMID study demonstrated a tumor-stabilizing effect when octreotide LAR (long acting repeatable) was used to treat patients with advanced midgut NET; however, there has been no consensus regarding its antitumor effect for PNET. Additionally, a recent result from the CLARINET study suggests that lanreotide autogel has an antitumor effect against nonfunctional NET including PNET. Further clinical study results are awaited.

Long-term disease control of a pancreatic neuroendocrine tumor with lanreotide autogel(®): a case report

The CLARINET study (ClinicalTrials.gov: NCT00353496) showed that somatostatin analogs are able to stabilize tumor growth in patients with intestinal and pancreatic neuroendocrine tumors (NETs). Here, we present a case of NET originating from the pancreatic tail that was treated with lanreotide Autogel(®). A 60-year-old patient underwent resection of a pancreatic NET with splenectomy and distal pancreatectomy. Four months after surgery, there was an increase in chromogranin A levels, along with a hypercaptating lesion of approximately 3.5 cm at the residual part of the pancreatic corpus. Treatment with 30 mg monthly-administered octreotide long-acting release (LAR) was initiated. After 3 months of treatment, a control CT scan revealed diffuse metastases in the liver, although the patient presented no symptoms and liver tests were normal. Due to difficulties with the administration of octreotide LAR, treatment was switched to lanreotide Autogel(®) 120 mg, administered as monthly deep-subcutaneous injections. Progression-free survival, as shown by 3-monthly CT scans, was obtained for 2 years without the need to increase the lanreotide Autogel(®) dose, and the patient reported no side effects. After these 2 years, deterioration of the patient's clinical status and weight loss were observed, along with increased size of the liver lesions and appearance of peritoneal metastases. Chemotherapy treatment with cisplatinum-etoposide was initiated, while the lanreotide Autogel(®) injections were continued. After three chemotherapy cycles, a rapid decline in the patient's quality of life was noted, and she requested discontinuation of the chemotherapy and lanreotide injections. One month later, the patient died due to clinical progressive disease.

Evaluation of somatostatin receptor subtype expression in human neuroendocrine tumors using two sets of new monoclonal antibodies

INTRODUCTION

The expression and reliable detection of somatostatin receptor subtypes (SSTR1-5) is a prerequisite for the successful use of somatostatin analogs in neuroendocrine tumors (NETs). Two sets of monoclonal antibodies (mAbs) against human SSTR1, 2A, 3 and 5 have recently been developed by two independent laboratories using rabbit and mouse hybridomas. Our aim was to evaluate the usefulness of both sets of mAbs for detection of SSTRs in NET samples as they are routinely collected in clinical practice.

METHODS

Mouse and rabbit mAbs were characterized in SSTR1, 2A, 3 and 5-transfected HEK293 cells and human archival samples of pancreatic tissue and NET. Comparative analysis of mAbs was also conducted by immunostaining of a tissue microarray composed of 75 cores of NET.

RESULTS

Immunohistochemical analysis of HEK293 cells showed that both rabbit and mouse mAbs specifically detect their cognate receptor subtype, with mild cytoplasmic cross-reactivity observed for rabbit mAbs. Both sets of mAbs labeled normal pancreatic islets and showed similar patterns of immunoreactivity in NET controls. Direct comparison of mAb sets using a NET tissue microarray revealed strong correlation between rabbit and mouse mAbs against SSTR1 and 5, and moderate correlation for SSTR3. The rabbit mAb against SSTR2A showed higher affinity for its cognate receptor than the corresponding mouse mAb, resulting in a more reliable detection of this SSTR.

CONCLUSIONS

mAbs from both sets are reliable tools for the detection of SSTR1, 3 and 5, whereas the rabbit mAb against SSTR2A is recommended for use in routine clinical testing due to its superior binding affinity.

Effects of somatostatin analog on splanchnic hemodynamics and plasma glucagon level in portal hypertensive rats

AIM: To investigate the effects of somatostatin analog on splanchnic hemodynamics and plasma glucagon level in portal hypertensive rats.

METHODS: Twenty-eight male Sprague-Dawley rats were equally divided into a intrahepatic portal hypertension (IHPH) model group (n = 14, established by injection of CCl₄) and a prehepatic portal hypertension (PHPH) model group (n = 14, established by stenosis of the portal vein). Animals in each group were subdivided into an octreotide treatment (injection) group and a control (normal saline injection) group. Seven age-matched unmodeled/untreated normal rats served as controls. The mean systemic arterial pressure (MSAP) and free portal venous pressure (FPP) were measured. The splanchnic blood flow was detected by injection of toad blood red cell labelled with ⁵¹Cr and ¹²⁵I·T₃. The concentration of plasma glucagon was determined by radioimmunoassay.

RESULTS: All rats with portal hypertension showed significantly decreased splanchnic blood flow and FPP in response to octreotide treatment, as well as markedly increased splanchnic vascular and portal venous resistance. The octreotide treatment did not appear to significantly lower the plasma glucagon levels in either the peripheral or the portal veins.

CONCLUSION: Octreotide induces a decrease in splanchnic blood flow in rats with portal hypertension, and this effect results primarily from direct vasoconstriction and to a lesser extent from decreased plasma glucagon level.