Antiproliferative effect of somatostatin analogs in gastroenteropancreatic neuroendocrine tumors

Somatostatin analogs were initially developed for the control of hormonal syndromes associated with neuro-endocrine tumors (NETs). In recent years, accumul ating data has supported their role as antiproliferative agents, capable of stabilizing tumor growth in patients with metastatic neuroendocrine malignancies, including carci-noid and pancreatic endocrine tumors. A phase Ⅲ, ran-domized, placebo-controlled trial has now demonstrated that octreotide long-acting repeatable (LAR) 30 mg can significantly prolong time to tumor progression among patients with metastatic midgut NETs regardless of functional status, chromogranin A level or age. In addition to signif icantly lengthening time to tumor pro-gression in the overall study population, subset analysis suggests that patients with low tumor burden are most likely to experience disease stabilization with octreotide LAR 30 mg, supporting the early use of octreotide LAR in patients with metastatic disease. Further research efforts are underway to evaluate the use of somatostatin analogs as antiproliferative agents in other types of gastroenteropancreatic-NETs. Ongoing studies are also evaluating novel somatostatin analogs and somatostatin analogs in combination with other anti-tumor therapies.

Effect of somatostatin analogue octreotide injected into the third cerebral ventricle on pentagastrin-induced gastric acid secretion in rats

AIM： To investigate the effect of long-lasting somatostatin analogue octreotide （Oct） injected into the third cerebral ventricle （TCV） on gastric acid secretion in rats. METHODS： TCVs were cannulated in male Wistar rats anesthetized with sodium pentobarbital. One week later acute gastric lumen perfusion was carried out and gastric acid was continuously washed with 37℃ saline by a perfusion pump. Gastric perfusion samples were collected every 10 min and titrated by 0.01 moL/L NaOH to neutral. On the basis of subcutaneous （sc） injection of pentagastrin （G-5, 160 μg/kg）, Oct （0.025 μg, 0.05 μg, 0.1 μg, n=12 in each group） or vehicle （pyrogen-free physiological saline, n = 10） was injected into the TCV, Before and after the TCV injection, 1 h total acid output （TAO） was determined and experimental data were expressed in change rate （%） of TAO. RESULTS： Oct （0.025, 0.05 and 0.1 μg） injected into the TCV resulted in change rate of 1.56% （P〉0.05）, 20.21% （P〈 0.01） and 37.82% of TAO （P〈 0.001）, respectively. Moreover, comparison in change rate of TAO among these 3 doses showed P〈 0.05 between 0.025μg and 0.05 μg, P〈 0.01 between 0.025 μg and 0.ling, and P〈 0.05 between 0.05μg and 0.1 μg. However, sc injection of 0.05 μg Oct had no effect on G-5 stimulated gastric acid secretion. CONCLUSION： Octreotide injected into the third cerebral ventricle inhibits gastrin-induced gastric acid secretion in a dose-dependent manner.

Acquired hepatocerebral degeneration in a metastatic neuroendocrine tumor long-term survivor——an update on neuroendocrine neoplasm’s treatment:A case report

BACKGROUND Metastatic small bowel low-grade neuroendocrine tumors(NETs)have a good prognosis.Surgery is the only curative treatment;however,this may induce advanced liver disease,particularly in long-term survivor patients.Acquired hepatocerebral degeneration or Parkinsonism in cirrhosis is characterized by rapidly progressive extrapyramidal symptoms in patients with advanced liver disease.CASE SUMMARY A 70-year-old man presented to the emergency department with diminished consciousness and disorientation,and was diagnosed with hepatic encephalopathy.The patient was diagnosed in 1993 with a metastatic small bowel NET,for which he twice underwent hepatic surgery,with metastatic resection in 1993 and a right hepatectomy in 2002 to remove two hepatic metastases.In 2003,the patient started first-line chemotherapy and in 2004 started the first of three consecutive biological treatments,followed by radio-molecular therapy,achieving stable disease for 14 years.Disease progression was identified and he underwent an endoscopic retrograde cholangiopancreatography.However,in 2019 advanced liver disease was identified.We diagnosed the development of acquired hepatocerebral degeneration,an unusual long-term side effect after multiple hepatic procedures.CONCLUSION The importance of regular and ongoing surveillance in long-term NET survivors who undergo hepatic procedures should be integrated into the therapeutic management plan,as some of these negative outcomes could be prevented.

Naloxone or Vagotomy Does Not Influence Centrally Octreotide-induced Inhibition of Gastric Acid Secretion in Rats

Summary： To investigate the effect of preceding naloxone injection into the third cerebroventricle or acute subdiaphragmatic vagotomy on the gastric acid secretion inhibited by the somatostatin analogue octreotide given by intracerebroventricular （icv） injection. The third ventricles were cannulated in male Wistar rats anesthetized with sodium pentobarbital. One week later, acute gastric lumen perfusion was carried out. The gastric perfusion samples were collected every 10 min and were titrated by 0.01 mol/L NaOH to neuter. On the basis of subcutaneous injection of pentagastrin （G-5, 160 g/kg）, icv injection of physiological saline （group A, n=20）, icv injection of octreotide （0.05 μ g） （group B, n=20）, icv injection of naloxone （2.5 μ g）＋octreotide （0.05 μg） （group C, n=20）, acute subdiaphragmatic vagotomy＋ icv injection of physiological saline （group D, n=20）, or acute subdia- phragrnatic vagotomy＋icv injection of octreotide （0.05 μg） （group E, n=20） were conducted. Before and after icv injection, 1-h total acid output （TAO） was determined and compared. The experimental data were expressed in change rate （%） of TAO. The change rates （%） of TAO were 4.60 % in group A, -20.35 % in group B, - 18.06 % in group C, 5.01% in group D and -21.59 % in group E, respectively. Comparison of group B or C versus group A showed that P〈0.01 and comparison between the group E versus group D showed that P〈0.01. Whereas the differences between group C and group B, group E and group B were not statistically significant （P〉0.05 for all）. The results indicate that the central inhibition of gastric acid secretion by octreotide may not be mediated by the endogenous opi- ate substance or its receptor and the peripheral pathway for icv injection of octreotide to suppress gastric acid secretion is via extra-vagus route.

Real-world treatment patterns of gastrointestinal neuroendocrine tumors: A claims database analysis

AIM To describe real-world treatment patterns of gastrointestinal neuroendocrine tumors(GI NET).METHODS In this retrospective cohort study,we used 2009-2014 data from 2 United States commercial claims databases to examine newly pharmacologically treated patients using tabular and graphical techniques. Treatments included somatostatin analogues(SSA),cytotoxic chemotherapy(CC),targeted therapy(TT),interferon(IF) and combinations. We identified patients at least 18 years of age,with ≥ 1 inpatient or ≥ 2 outpatient claims for GI NET who initiated pharmacologic treatment from 7/1/09-6/30/14. A 6 mo clean period prior to first treatment ensured patients were newly treated. Patients were followed until end of enrollment or the study end date,whichever was first.RESULTS We identified 2258 newly treated GI NET patients: mean(SD) age was 55.6 years(SD = 9.7),47.2% of the patients were between 55 and 64 years,and 48.8% were female. All regions of the United States were represented. 59.6% started first-line therapy with SSA monotherapy(964 with octreotide LAR,380 with octreotide SA,and 1 with lanreotide),33.3% CC,3.6% TT,and 0.5% IF. The remainder received combinations. Mean follow up was 576 d. Overall mean first-line therapy duration was 361 d(449 d for SSA,215 for CC,267 for TT). 58.9% of patients had no pharmacological treatment beyond first line. The most common secondline was combination therapy with SSA. In graphical pattern analysis,there was no clear pattern visible after first line therapy.CONCLUSION In this study,60% of patients initiated treatment with SSA alone or in combination. The relatively long time to discontinuation suggests possible sustained effectiveness and tolerability.

Everolimus halts hepatic cystogenesis in a rodent model of polycystic-liver-disease

AIM To develop a MRI-based method for accurate determination of liver volume(LV) and to explore the effect of long-term everolimus(EVR) treatment on LV in PCK rats with hepatomegaly. METHODS Thirty-one female PCK rats(model for polycystic-liverdisease: PCLD) were randomized into 3 groups and treatment was started at 16 wk, at the moment of extensive hepatomegaly(comparable to what is done in the human disease). Animals received: controls(n = 14), lanreotide(LAN: 3 mg/kg per 2 wk)(n = 10) or everolimus(EVR: 1 mg/kg per day)(n = 7). LV was measured at week 16, 24, 28. At week 28, all rats were sacrificed and liver tissue was harvested. Fibrosis was evaluated using quantitative image analysis. In addition, gene(quantitative RT-PCR) and protein expression(by Western blot) of the PI3K/Ak T/m TOR signaling pathway was investigated. RESULTS LV determination by MRI correlated excellent with the ex vivo measurements(r = 0.99, P < 0.001). The relative changes in LV at the end of treatment were:(controls) +31.8%;(LAN) +5.1% and(EVR) +8.8%, indicating a significantly halt of LV progression compared with controls(respectively, P = 0.01 and P = 0.04). Furthermore, EVR significantly reduced the amount of liver fibrosis(P = 0.004) thus might also prevent the development of portal hypertension. There was no difference in phosphorylation of Akt(Threonine 308) between LAN-treated PCK rats control PCK rats, whereas S6 was significantly more phosphorylated in the LAN group. Phosphorylation of Akt was not different between controls and EVR treated rats, however, for S6 there was significantly less phosphorylation in the EVR treated rats. Thus, both drugs interact with the PI3K/Ak T/m TOR signaling cascade but acting at different molecular levels.CONCLUSION Everolimus halts cyst growth comparable to lanreotide and reduces the development of fibrosis. m TORinhibition should be further explored in PCLD patients especially those that need immunosuppression.

Orbital lesions,an exceedingly rare site of neuroendocrine tumor metastasis

Neuroendocrine tumors are rare neoplasms arising primarily in the gastrointestinal tract and lung.The liver is the most common site of metastases,but these tumors can rarely metastasize to atypical sites.Surgery is the only curative approach while the optimal medical treatment is debated.From this perspective,a multidisciplinary approach for each single case becomes very important.In this report we describe the case of a male affected by a single intraorbital metastasis from a midgut well differentiated neuroendocrine tumor.The patient refused surgical removal and therefore he was at first treated with stereotactic radiotherapy and systemic treatment with a somatostatin analog(SSA).After achieving a stable disease for four months he underwent primary tumor resection.Six years after the initial diagnosis,the patient is currently stable and receiving SSA at standard dose.