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Background Long‐term medical management of hypersomatotropism (HS) in cats has proved unrewarding. Pasireotide, a novel somatostatin analogue, decreases serum insulin‐like growth factor 1 (IGF‐1) and improves insulin sensitivity in cats with HS when administered as a short‐acting preparation. Objectives Assess once‐monthly administration of long‐acting pasireotide (pasireotide LAR) for treatment of cats with HS. Animals Fourteen cats with HS, diagnosed based on diabetes mellitus, pituitary enlargement, and serum IGF‐1 > 1000 ng/mL. Methods Uncontrolled, prospective cohort study. Cats received pasireotide LAR (6–8 mg/kg SC) once monthly for 6 months. Fructosamine and IGF‐1 concentrations, and 12‐hour blood glucose curves (BGCs) were assessed at baseline and then monthly. Product of fructosamine concentration and insulin dose was calculated as an indicator of insulin resistance (Insulin Resistance Index). Linear mixed‐effects modeling assessed for significant change in fructosamine, IGF‐1, mean blood glucose (MBG) of BGCs, insulin dose (U/kg) and Insulin Resistance Index. Results Eight cats completed the trial. Three cats entered diabetic remission. Median IGF‐1 (baseline: 1962 ng/mL [range 1051–2000 ng/mL]; month 6: 1253 ng/mL [524–1987 ng/mL]; P < .001) and median Insulin Resistance Index (baseline: 812 μmolU/L kg [173–3565 μmolU/L kg]; month 6: 135 μmolU/L kg [0–443 μmolU/L kg]; P = .001) decreased significantly. No significant change was found in mean fructosamine (baseline: 494 ± 127 μmol/L; month 6: 319 ± 113.3 μmol/L; P = .07) or MBG (baseline: 347.7 ± 111.0 mg/dL; month 6: 319.5 ± 113.3 mg/dL; P = .11), despite a significant decrease in median insulin dose (baseline: 1.5 [0.4–5.2] U/kg; 6 months: 0.3 [0.0–1.4] U/kg; P < .001). Adverse events included diarrhea (n = 11), hypoglycemia (n = 5), and worsening polyphagia (n = 2). Conclusions and Clinical Importance Pasireotide LAR is the first drug to show potential as a long‐term management option for cats with HS.

Objective: To examine pasireotide's effect on intestinal anastomotic healing under physiological conditions and following preoperative whole-body irradiation.Material and methods: Forty-five male Wistar rats received an ileoileal end-to-end anastomosis. Group 1 (Co, n = 9) served as control. Group 2 (SOM, n = 10) received pasireotide (60 mg/kg) 6 days preoperatively. Group 3 (R-Co, n = 13) was subjected to 8 Gy whole-body irradiation 4 days preoperatively. Finally, group 4 (R-SOM, n = 13) received pasireotide 6 days preoperatively and whole-body irradiation 4 days preoperatively. On postoperative day 4, anastomotic bursting pressure, histology, IGF-1 staining, and collagen density were examined.Results: Mortality was higher in irradiated animals (30.8% vs. 5.3%, p = 0.021), and anastomotic bursting pressure was significantly lower (median, R-Co = 83 mmHg; R-SOM = 101 mmHg; Co = 149.5 mmHg; SOM = 169 mmHg). Inflammation measured by leukocyte infiltration following irradiation was reduced (p = 0.023), and less collagen was observed, though this was not statistically significant. Bursting pressure did not significantly differ between Co and SOM and between R-Co and R-SOM animals respectively. Semi-quantitative scoring of IGF-1, fibroblast bridging, or collagen density did not reveal significant differences among the groups.Conclusion: Whole-body irradiation decreases the quality of intestinal anastomotic wound healing and increases mortality. Pasireotide does not significantly lessen this detrimental effect. [ABSTRACT FROM AUTHOR]

Background Long-term medical management of hypersomatotropism ( HS) in cats has proved unrewarding. Pasireotide, a novel somatostatin analogue, decreases serum insulin-like growth factor 1 ( IGF-1) and improves insulin sensitivity in cats with HS when administered as a short-acting preparation. Objectives Assess once-monthly administration of long-acting pasireotide (pasireotide LAR) for treatment of cats with HS. Animals Fourteen cats with HS, diagnosed based on diabetes mellitus, pituitary enlargement, and serum IGF-1 > 1000 ng/mL. Methods Uncontrolled, prospective cohort study. Cats received pasireotide LAR (6-8 mg/kg SC) once monthly for 6 months. Fructosamine and IGF-1 concentrations, and 12-hour blood glucose curves ( BGCs) were assessed at baseline and then monthly. Product of fructosamine concentration and insulin dose was calculated as an indicator of insulin resistance (Insulin Resistance Index). Linear mixed-effects modeling assessed for significant change in fructosamine, IGF-1, mean blood glucose ( MBG) of BGCs, insulin dose (U/kg) and Insulin Resistance Index. Results Eight cats completed the trial. Three cats entered diabetic remission. Median IGF-1 (baseline: 1962 ng/mL [range 1051-2000 ng/mL]; month 6: 1253 ng/mL [524-1987 ng/mL]; P < .001) and median Insulin Resistance Index (baseline: 812 μmolU/L kg [173-3565 μmolU/L kg]; month 6: 135 μmolU/L kg [0-443 μmolU/L kg]; P = .001) decreased significantly. No significant change was found in mean fructosamine (baseline: 494 ± 127 μmol/L; month 6: 319 ± 113.3 μmol/L; P = .07) or MBG (baseline: 347.7 ± 111.0 mg/dL; month 6: 319.5 ± 113.3 mg/dL; P = .11), despite a significant decrease in median insulin dose (baseline: 1.5 [0.4-5.2] U/kg; 6 months: 0.3 [0.0-1.4] U/kg; P < .001). Adverse events included diarrhea (n = 11), hypoglycemia (n = 5), and worsening polyphagia (n = 2). Conclusions and Clinical Importance Pasireotide LAR is the first drug to show potential as a long-term management option for cats with HS. [ABSTRACT FROM AUTHOR]

Purpose: To demonstrate the feasibility of MRI to monitor longitudinally the fate of PLGA microparticles in muscle tissue after intramuscular injection in rats using standard equipment. Methods: MRI was performed at different time points and until day 28 after intramuscular administration of microparticles. Image segmentation was used to quantify the MRI signals. Histology was performed at selected time points to validate the in vivo observations. The SOM230-long acting release formulation was used as test compound. Results: Microparticles were detected in vivo until 28 days following their administration. Imaging and histology data indicated that the MRI signals followed three phases: in an early phase (48 h after injection), vehicle, edema and hydration of microparticles contributed to the signals. In the second (days 3-17) and third phases (day 17 onward), microparticle hydration was the main contributor. SOM230 in blood displayed peaks at days 2 and 17. Conclusion: MRI was suitable to follow longitudinally the presence of PLGA microparticles in the rat muscle without labeling them. This is advantageous, because labeling could potentially alter the properties and pharmacokinetics of the microparticles. Data were consistent with an initial compound release followed by diffusion and microparticle erosion as main mechanisms of SOM230 release. [ABSTRACT FROM AUTHOR]

A novel liquid chromatographic method with tandem mass spectrometric detection (LC–MS/MS) for the determination of Pasireotide (SOM230) was developed and validated with a dynamic range of 0.5–250 ng/ml using 50 μl of monkey plasma. SOM230 and the internal standard, [M + 6]SOM230, were extracted from monkey plasma via μElution SPE. The acidified sample matrix was loaded onto the preconditioned Waters SPE plate for further processing. The analyte was eluted from the SPE plate using freshly prepared elution solvent, which was followed by dilution and LC–MS/MS analysis. By eliminating a step of evaporation of the SPE eluent, instead, injecting the eluent after a simple dilution, compound loss due to non-specific binding to the 96-well materials was prevented. Furthermore, freshly prepared elution solution was found a key to optimal extraction recovery of the analyte from monkey plasma. The optimal chromatographic separation was achieved on an Atlantis dC18 (50 × 2.1 mm, 5 μm particle size) column using gradient elution with a total analysis cycle time approximately 4 min per injection. The mobile phases were water containing 0.5% acetic acid and 0.05% trifluoroacetic acid (TFA) (mobile phase A) and acetonitrile containing 0.5% acetic acid and 0.05% TFA (mobile phase B). The incorporation of TFA (0.05%, v/v) and acetic acid (0.5%, v/v) into the mobile phases was accompanied by the improved chromatography and minimized carryover due to the HPLC column. The current method was validated for specificity, sensitivity, matrix effect, recovery, linearity, accuracy and precision, dilution integrity, batch size and stability. The accuracy and precision for the LLOQs (0.5 ng/ml) were within ±5.6% bias and ≤7.8% CV, respectively. From the intra-day and inter-day evaluations, the precision of the other QC samples (1.5, 7.5, 75 and 190 ng/ml) ranged from 2.7 to 4.9% CV and the accuracy (% bias) from −1.3 to 7.3%, respectively. Additional assessment of incurred sample reanalysis (ISR) was conducted to demonstrate the ruggedness and robustness of the assay method. The validated method was successfully implemented to support a toxicity study in monkeys administered with 5 and 30 mg of SOM230 in a single intramuscular injection of a long acting release (LAR) formulation. [ABSTRACT FROM AUTHOR]

Introduction Pasireotide (SOM230) is a somatostatin analog with high binding affinity for somatostatin receptors including sst1, 2, 3 and 5 and inhibit insulin like growth factor-1. Blocking of IGF-1 receptor (IGF-1R) in combination with cytotoxic chemotherapy has demonstrated additive or synergistic activity in pre-clinical models. This study aimed to evaluate the maximum tolerated dose (MTD) of pasireotide in combination with standard FOLFIRI (5-fluorouracil, leucovorin and irinotecan) regimen in patients with gastrointestinal malignancies. Methods This was a phase 1, 3 + 3 design, open-label dose escalation study conducted in sequential cohorts to determine the MTD of pasireotide in combination with FOLFIRI. All patients had gastrointestinal malignancies and were previously treated. Sixteen patients enrolled in five dose cohorts at pasireotide doses of 40, 60, 80, 100 and 120 mg were evaluated for safety and tolerability of the combination. Results The tumor types of the enrolled subjects included esophageal ( n = 5), biliary tract ( n = 3), colon ( n = 3), gastric ( n = 2), pancreatic ( n = 1), anal ( n = 1) and small bowel ( n = 1). No dose limiting toxicities were observed. The most common adverse events related to the study treatment included hyperglycemia (81 %), neutropenia (62 %), thrombocytopenia (44 %), anorexia (44 %), dehydration (25 %) and elevated alkaline phosphatase (25 %). Two patients had partial response and 7 patients had stable disease. Plasma levels of IGF-1 and IGFBP-3 were significantly reduced after treatment with pasireotide. Discussion Combination of pasireotide and FOLFIRI has manageable safety profile and is feasible in patients with gastrointestinal malignancies. Preliminary signals of activity were observed. Larger phase II trials are warranted. [ABSTRACT FROM AUTHOR]

A rational drug design approach involving transposition of functional groups from SRIF into a reduced size cyclohexapeptide template has led to the discovery of SOM230, a novel, stable cyclohexapeptide somatostatin mimic which exhibits unique high affinity binding to human somatostatin receptors (sst1-5). This unique receptor subtype binding profile, in particular the exceptional high affinity binding to sst5, led to SOM230 being approved by EMEA and FDA in 2012 as the first effective pituitary directed therapeutic modality for Cushing's disease.

Background: Acromegaly is an insidious neuroendocrine disorder caused by hypersecretion of growth hormone (GH) by a somatotroph adenoma. Somatostatin receptor ligands (SRLs) are recommended as first-line medical therapy in patients for whom surgery has failed or is contraindicated. There are 5 known somatostatin receptor subtypes (SSTRs), 2 of which, i.e. SSTR2 and SSTR5, are expressed by a majority of somatotroph adenomas. The currently available SRLs, i.e. octreotide and lanreotide, primarily bind to SSTR2. Pasireotide (SOM230) is a new multireceptor-targeted SRL which has a broader binding profile and an increased affinity for SSTR1, 2, 3, and 5. Methods: PubMed searches were performed to identify all of the available published English language data on pasireotide with regard to the mechanism of action, in vitro effects, and clinical data. Results: Preclinical studies have demonstrated that pasireotide has a broader range of functional activity than octreotide. Recently, the efficacy of pasireotide in attenuating GH and insulin-like growth factor 1 (IGF-1) levels in patients with acromegaly has been evaluated in phase III clinical trials. Pasireotide demonstrated superiority over octreotide in achieving biochemical control (i.e. GH ≤2.5 µg/l and age- and sex-matched IGF-1 normalization) in patients with acromegaly, as well as significant efficacy in treating patients who were previously inadequately controlled on the maximum allowed doses of octreotide and lanreotide. Pasireotide-induced hyperglycemia was the most concerning adverse event but was reversible upon discontinuation of pasireotide. Conclusion: The clinical data support pasireotide as a promising new therapy for the treatment of acromegaly, and the long-acting formulation was recently approved in the US and Europe for the treatment of acromegaly. © 2015 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

In a previous 15-day, Phase II study of patients with de novo or persistent/recurrent Cushing's disease (core study), treatment with pasireotide 600 μg sc bid reduced urinary free cortisol (UFC) levels in 76 % of patients and normalized UFC in 17 %. The objective of this study was to evaluate the efficacy and safety of extended treatment with pasireotide. This was a planned, open-ended, single-arm, multicenter extension study (primary endpoint: 6 months). Patients aged ≥18 years with Cushing's disease who completed the core study could enter the extension if they achieved UFC normalization at core study end and/or obtained significant clinical benefit. Of the 38 patients who completed the core study, 19 entered the extension and 18 were included in the efficacy analyses (three responders, 11 reducers, four non-reducers in the core study). At data cut-off, median treatment duration in the extension was 9.7 months (range: 2 months to 4.8 years). At extension month 6, 56 % of the 18 patients had lower UFC than at core baseline and 22 % had normalized UFC. Of the four patients who remained on study drug at month 24, one had normalized UFC. Reductions in serum cortisol, plasma adrenocorticotropic hormone, body weight and diastolic blood pressure were observed. The most common adverse events were mild-to-moderate gastrointestinal disorders and hyperglycemia. Pasireotide offers a tumor-directed medical therapy that may be effective for the extended treatment of some patients with Cushing's disease. [ABSTRACT FROM AUTHOR]

Idiopathic pulmonary fibrosis is a progressive and lethal disease, characterized by loss of lung elasticity and alveolar surface area, secondary to alveolar epithelial cell injury, reactive inflammation, proliferation of fibroblasts, and deposition of extracellular matrix. The effects of oropharyngeal aspiration of bleomycin in Sprague-Dawley rats and C57BL/6 mice, as well as of intratracheal administration of ovalbumin to actively sensitized Brown Norway rats on total lung volume as assessed noninvasively by magnetic resonance imaging (MRI) were investigated here. Lung injury and volume were quantified by using nongated or respiratory-gated MRI acquisitions [ultrashort echo time (UTE) or gradient-echo techniques]. Lung function of bleomycin-challenged rats was examined additionally using a flexi- Vent system. Postmortem analyses included histology of collagen and hydroxyproline assays. Bleomycin induced an increase of MRIassessed total lung volume, lung dry and wet weights, and hydroxyproline content as well as collagen amount. In bleomycin-treated rats, gated MRI showed an increased volume of the lung in the inspiratory and expiratory phases of the respiratory cycle and a temporary decrease of tidal volume. Decreased dynamic lung compliance was found in bleomycin-challenged rats. Bleomycin-induced increase of MRI-detected lung volume was consistent with tissue deposition during fibrotic processes resulting in decreased lung elasticity, whereas influences by edema or emphysema could be excluded. In ovalbumin-challenged rats, total lung volume quantified by MRI remained unchanged. The somatostatin analog, SOM230, was shown to have therapeutic effects on established bleomycin-induced fibrosis in rats. This work suggests MRI-detected total lung volume as readout for tissue-deposition in small rodent bleomycin models of pulmonary fibrosis. [ABSTRACT FROM AUTHOR]

Pasireotide has a broader somatostatin receptor binding profile than other somatostatin analogues. A 16-week, Phase II trial showed that pasireotide may be an effective treatment for acromegaly. An extension to this trial assessed the long-term efficacy and safety of pasireotide. This study was an open-label, single-arm, open-ended extension study (primary efficacy and safety evaluated at month 6). Patients could enter the extension if they achieved biochemical control (GH ≤ 2.5 μg/L and normal IGF-1) or showed clinically relevant improvements during the core study. Thirty of the 60 patients who received pasireotide (200-900 μg bid) in the core study entered the extension. At extension month 6, of the 26 evaluable patients, six were biochemically controlled, of whom five had achieved control during the core study. Normal IGF-1 was achieved by 13/26 patients and GH ≤ 2.5 μg/L by 12/26 at month 6. Nine patients received pasireotide for ≥24 months in the extension; three who were biochemically controlled at month 24 had achieved control during the core study. Of 29 patients with MRI data, nine had significant (≥20 %) tumor volume reduction during the core study; an additional eight had significant reduction during the extension. The most common adverse events were transient gastrointestinal disturbances; hyperglycemia-related events occurred in 14 patients. Twenty patients had fasting plasma glucose shifted to a higher category during the extension. However, last available glucose measurements were normal for 17 patients. Pasireotide has the potential to be an effective, long-term medical treatment for acromegaly, providing sustained biochemical control and significant reductions in tumor volume. [ABSTRACT FROM AUTHOR]

Abstract: SOM230 (pasireotide, Signifor), a recently developed somatostatin analog, has been tested in ACTH-secreting pituitary tumors with promising results. No study has yet evaluated whether this analog also directly affects adrenal steroid production. The aim of the current study was to evaluate whether SOM230 modulates corticosteroid secretion by normal adrenals in vitro. Primary cultures from normal human and rat adrenals were incubated with 10–100nM SOM230 with and without 10nM ACTH. Dose–response studies with 1nM–1μM SOM230 were performed on rat adrenals. Cortisol/corticosterone levels in medium were measured after 4 and 24h. SOM230 (10nM) significantly increased corticosteroid levels after 24h incubation in both human (36.4±0.43ng/well vs 27.7±3.17ng/well, p <0.05) and rat (16.2±1.16ng/well vs 11.6±0.92ng/well p <0.05) adrenals; lesser effects were observed with 100nM SOM (33.4±2.59ng/well vs 27.7±3.17ng/well p <0.05; 13.4±0.82ng/well vs 11.6±0.92ng/well, N.S. vs baseline secretion for human and rat adrenals, respectively). Dose–response curves confirmed maximal effect at 10nM SOM230. The corticosteroid secretory response to ACTH was unaffected by SOM230 co-incubation. In conclusion, SOM230 exerts a moderate stimulatory effect on adrenal corticosteroid secretion in vitro. This argues against a direct adrenal involvement in the clinical efficacy of SOM230 in patients with ACTH-secreting pituitary tumors and widens the known range of action of SOM230. [Copyright &y& Elsevier]

Pasireotide is a novel, multireceptor-targeted somatostatin analogue with high affinity for sst1,2,3 and sst5 under clinical evaluation in tumors of neuroendocrine origin, including Cushing’s disease, acromegaly, and neuroendocrine tumors. In this phase I, open-label, multicenter study, the pharmacokinetics and safety of a single subcutaneous (SC) injection of pasireotide 600 µg were evaluated in adults with normal hepatic function (n = 15) and mild (n = 6), moderate (n = 7), or severe hepatic impairment (n = 6). Following a single dose of pasireotide SC 600 µg, there were no significant differences in the plasma exposure of pasireotide between participants with normal hepatic function or mild hepatic impairment. Subjects with moderate and severe hepatic impairment showed an increase in AUC∞ by 56% and 42%, respectively; this increase was 60% and 79% respectively, after adjusting for differences in age, BMI, and baseline serum albumin level between treatment groups. The incidence and severity of adverse events were similar across cohorts, with no clinically relevant differences in type or frequency of adverse events between cohorts. In conclusion, a single dose of pasireotide SC 600 µg was well tolerated in subjects with hepatic impairment. Drug exposure in subjects with mild hepatic impairment was similar to that seen in healthy volunteers, whereas subjects with moderate and severe hepatic impairment experienced higher exposure to pasireotide. Adjustment of the pasireotide dose may be required for patients with moderate and severe hepatic impairment. [ABSTRACT FROM PUBLISHER]

Abstract: Background: Pasireotide is a multireceptor-targeted somatostatin analogue with high binding affinity for somatostatin receptor subtypes SST 1, 2, 3, and 5. Objective: To evaluate the safety profile, tolerability, and pharmacokinetic profile of pasireotide in single- and divided-dose regimens in healthy volunteers. Methods: A single-center, open-label, ascending-dose study was performed in healthy volunteers. Pasireotide, 900, 1200, and 1500 μg SC, was administered as either a single dose or as two divided doses given 12 hours apart, with a 7-day washout period between treatments. Results: Seventeen men (median age, 26 years) were enrolled. Their median weight was 81 kg, and 65% were white. One participant dropped out because of a grade 2 adverse event; most other adverse events were mild and affected the gastrointestinal tract. Blood glucose concentration increased after pasireotide administration, but returned to normal within 10 hours. After single-dose administration, pasireotide plasma concentration peaked rapidly at 15 minutes to 1 hour after dosing, followed by a tri-exponential (α, β, and γ phases) decline over time. Mean t½ values during the α, β, and γ phases were approximately 2 to 3, 12 to 17, and 54 to 97 hours, respectively. In the single-dose cohort, the mean (SD) AUC∞ was 110 (29), 149 (42), and 188 (52) h · ng/mL in the 900-, 1200-, and 1500-μg groups, respectively. Time to reach Cmax was 0.69 (0.41), 0.59 (0.38), and 0.56 (0.18) hours in the 900-, 1200-, and 1500-μg groups, respectively. AUC∞ values were similar in the single-dose and divided-dose cohorts. Mean total body clearance was 8 to 9 L/h across the dosage groups and dosing regimens, indicating a linear pharmacokinetic profile between doses. Conclusions: When administered as a single- or divided-dose regimen, pasireotide had a favorable tolerability profile in this selected group of healthy male volunteers. Its pharmacokinetic profile indicated rapid absorption, low clearance, high volume of distribution, and a long terminal half-life. [Copyright &y& Elsevier]

SOM230 (pasireotide) is a multiligand somatostatin (SRIF) analog able to bind to somatostatin receptor (SSTR) subtypes 1, 2, 3 and 5, and trigger antisecretory and antiproliferative signaling cascades. Canines have become in vivo models to test the pharmacological treatment of corticotropinomas because they frequently develop Cushing's disease in a spontaneous manner, due to adrenocorticotropic hormone (ACTH)-producing pituitary adenomas. Different levels of expression of SSTR2 and SSTR5 have been shown in both mouse AtT20 cells and canine tumoral corticotropinoma cells. The objective of this study was to evaluate whether SOM230 controls both tumor cell growth and hormone synthesis, therefore controlling the disease. SOM230 was tested in dogs suffering from Cushing's disease (10 animals were treated continuously during 6 months, and another 10 were treated with 3 cycles consisting of 2 months of treatment followed by a 2-month rest period). A significant decrease in ACTH, urinary cortisol creatinine ratio, adenoma size (magnetic nuclear resonance) and improvement of clinical signs were obtained, without side effects. AtT20 cells treated with SOM230 suppressed pro-opiomelanocortin (POMC) promoter activity through SSTR2, via the Gi α-subunit, and reduced Nur77/Nurr1 transcriptional activity. We conclude that SOM230, in addition to its well-described antisecretory effects, inhibits, as shown in AtT20 cells, ACTH synthesis at the POMC transcriptional level, an effect mediated mainly through SSTR2, and limits tumor growth. The controlled Cushing's disease in the dogs that received the treatment indicates that SOM230 has a potential therapeutic use in humans suffering from Cushing's disease. Copyright © 2011 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Mammary hyperplasia increases breast cancer risk. Tamoxifen prevents breast cancer in women with atypical hyperplasia, but has serious side effects. As estradiol action requires IGF-I, direct inhibition of IGF-I action theoretically might be an efficacious alternative to tamoxifen. After hypophysectomy and oophorectomy, 21-day-old female rats were treated with GH and E After 7 days all terminal end buds (TEBs) and 75% of ducts became hyperplastic. Co-treatment with pasireotide, a somatostatin analog that blocks GH secretion and IGF-I action in the mammary gland, prevented hormone-induced hyperplasia. The number and size of TEBs and moderately or floridly hyperplastic ducts was reduced by pasireotide ( P < 0.01). In contrast, the same concentration of octreotide, which has a more selective somatostatin receptor subtype binding profile, was less effective than pasireotide. Tamoxifen inhibited hyperplasia when used alone with GH + E, but did not add to the inhibitory effect of pasireotide when the two treatments were combined. Both pasireotide and tamoxifen acted via the IGF-I receptor signaling pathway and both were found to inhibit mammary cell proliferation and stimulate apoptosis. The number of epithelial cells expressing phosphorylated insulin receptor substrate (IRS)-1 in response to GH and E was reduced by pasireotide, as was staining intensity. These results support the concept that IGF-I inhibition, in this case by pasireotide, inhibits E and GH-induced mammary hyperplasia. As tamoxifen did not further increase the inhibitory effect of pasireotide, the peptide appears to be at least as effective as tamoxifen in preventing GH + E-induced mammary hyperplasia. [ABSTRACT FROM AUTHOR]

Abstract: Among clinically relevant somatostatin functions, agonist-induced somatostatin receptor subtype 2 (sst2) internalization is a potent mechanism for tumor targeting with sst2 affine radioligands such as octreotide. Since, as opposed to octreotide, the second generation multi-somatostatin analog SOM230 (pasireotide) exhibits strong functional selectivity, it appeared of interest to evaluate its ability to affect sst2 internalization in vivo. Rats bearing AR42J tumors endogenously expressing somatostatin sst2 receptors were injected intravenously with SOM230 or with the [Tyr3, Thr8]-octreotide (TATE) analog; they were euthanized at various time points; tumors and pancreas were analyzed by immunohistochemistry for the cellular localization of somatostatin sst2 receptors. SOM230-induced sst2 internalization was also evaluated in vitro by immunofluorescence microscopy in AR42J cells. At difference to the efficient in vivo sst2 internalization triggered by intravenous [Tyr3, Thr8]-octreotide, intravenous SOM230 did not elicit sst2 internalization: immunohistochemically stained sst2 in AR42J tumor cells and pancreatic cells were detectable at the cell surface at 2.5min, 10min, 1h, 6h, or 24h after SOM230 injection while sst2 were found intracellularly after [Tyr3, Thr8]-octreotide injection. The inability of stimulating sst2 internalization by SOM230 was confirmed in vitro in AR42J cells by immunofluorescence microscopy. Furthermore, SOM230 was unable to antagonize agonist-induced sst2 internalization, neither in vivo, nor in vitro. Therefore, SOM230 does not induce sst2 internalization in vivo or in vitro in AR42J cells and pancreas, at difference to octreotide derivatives with comparable sst2 binding affinities. These characteristics may point towards different tumor targeting but also to different desensitization properties of clinically applied SOM230. [Copyright &y& Elsevier]

More than 30 years have passed since somatostatin was discovered and its hormonal function defined. The wide range of anatomical distribution and actions of somatostatin and its receptors have stimulated intense scientific and clinical interest. The development of somatostatin analogues helped define its usefulness in the treatment of endocrine diseases and cancer. The molecular cloning of five distinct subtypes of somatostatin receptors in the 1980s has significantly increased our insight into the biology of somatostatin and its receptor subtypes and has led to the design and development of subtype-selective peptides and nonpeptide agonists and antagonists. In the future, the development of somatostatin-receptor-mediated treatment will go along different lines. Tumor-targeted radioactive treatment based on somatostatin analogues will be further developed and improved. New somatostatin analogues will come into clinical practice, both receptor subtype-specific analogues, but also pan-receptor analogues. One is currently in clinical trial – SOM230 – which is a cyclo-hexapeptide binding with high affinity to receptor type 1, 2, 3 and 5, but not 4. It has already shown activity both in acromegaly and in neuroendocrine gastrointestinal tumors. Preclinical studies on somatostatin analogues, coupled to cytotoxic agents, have shown rather promising results and will hopefully be further developed in clinical trials. Another interesting area is treatment of neuroendocrine gut tumors with ultra-high doses of somatostatin analogues, which has demonstrated significant clinical effects in patients resistant to standard-dose treatment with the same somatostatin analogue. Copyright © 2004 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Functional gastroenteropancreatic tumors express all 5 somatostatin receptor subtypes (sst) in different quantities. Octreotide and lanreotide treat patients with these tumors by binding preferentially to sst2 and, to a lesser extent, to sst3 and sst5 receptors, thereby controlling prominent symptoms caused by hormone hypersecretion (diarrhea and flushing). Although symptoms initially improve in most patients, a loss of response occurs in about 50% during continuous treatment. The functional activity at sst receptors of SOM230, a new multiligand somatostatin analog, has been described and compared with that of somatostatin (SRIF-14) and octreotide. These data show that SOM230 is a full agonist with nanomolar potency at sst1,2,3 and sst5 receptors. The multiligand activity profile of SOM230, together with its nondesensitizing inhibitory effect on growth hormone and insulin-like growth factor-I secretion in rats, may underlie its successful use in clinical trials and its potential for use in refractory patients with carcinoid tumors. Copyright © 2004 S. Karger AG, Basel [ABSTRACT FROM AUTHOR]

Acromegaly is a neuroendocrine disorder caused by excess secretion of GH by somatotroph tumor cells. It is often treated with somatostatin receptor (SSTR) 2 agonists, which suppress GH secretion. SOM230 is a somatostatin analogue that targets multiple SSTRs and was recently approved for patients with treatment-resistant acromegaly. Previous reports indicate that SOM230 may function as a biased agonist, suggesting that its ability to selectively activate SSTR-dependent signaling events may contribute to its therapeutic efficacy. To better understand how SOM230 modulates Sstr2A function, which is the most commonly expressed SSTR in somatotrophs, we used real-time assays to study SOM230-dependent signaling in rat pituitary tumor cells. We observed that SOM230 suppressed cAMP production in a G α i-dependent manner, similar to conventional Sstr2A agonists. However, it did not cause receptor internalization as would be expected for an Sstr2A agonist. Surprisingly, SOM230 did not cause membrane hyperpolarization, which is an important mechanism by which Sstr2a activation suppresses intracellular calcium (Ca 2+ ) accumulation and GH secretion. In fact, SOM230 inhibited the ability of conventional somatostatin analogues to control membrane potential. However, SOM230 still inhibited intracellular Ca 2+ accumulation in a novel, G βγ -dependent manner. These studies show that SOM230 exhibits strong agonist bias in regulating signaling pathways downstream of Sstr2A that control GH secretion.

Background: Pasireotide (SOM230; Novartis Inc, Basel, Switzerland) is a multitargeted somatostatin receptor analogue likely to treat the neuroendocrine, and docetaxel resistant components within metastatic castrate-resistant prostate cancer (mCRPC). This phase I trial tested the combination of pasireotide, docetaxel, and prednisone in pretreated mCRPC., Patients and Methods: Chemotherapy naive mCRPC patients received docetaxel 75 mg/m 2 intravenously every 21 days and pasireotide intramuscularly every 28 days at escalating dose levels of 40, 60, and 80 mg. Maximum tolerated dose and recommended phase II dose (RP2D) were assessed., Results: Eighteen patients were enrolled with a median age of 65 (range, 49-75) years, and pretherapy prostate-specific antigen of 259.9 ng/mL. The dose-limiting toxicities were Grade 4 hyperglycemia unresponsive to therapy and Grade 4 neutropenia lasting for > 7 days in 1 patient each occurring at the 80-mg dose level of pasireotide. The RP2D was determined at 60 mg every 28 days. Four patients at the 60 mg dose had Grade 3 or 4 hyperglycemia, which responded adequately to therapy. Median time to progression and survival were 7.2 and 18.3 months, respectively. Three of 6 patients with circulating tumor cells ≥5 converted to circulating tumor cells < 5 post therapy. The insulin like growth factor-1 levels revealed a median 51% decrease after therapy. The neuron-specific enolase and chromogranin did not show any marked change., Conclusion: The addition of pasireotide to docetaxel and prednisone is clinically feasible at a dose level of 60 mg every 28 days. The combination showed potential for clinical efficacy but needs to be compared with the standard docetaxel and prednisone regimen., (Copyright © 2018 Elsevier Inc. All rights reserved.)

Purpose: To demonstrate the feasibility of MRI to monitor longitudinally the fate of PLGA microparticles in muscle tissue after intramuscular injection in rats using standard equipment., Methods: MRI was performed at different time points and until day 28 after intramuscular administration of microparticles. Image segmentation was used to quantify the MRI signals. Histology was performed at selected time points to validate the in vivo observations. The SOM230-long acting release formulation was used as test compound., Results: Microparticles were detected in vivo until 28 days following their administration. Imaging and histology data indicated that the MRI signals followed three phases: in an early phase (≤ 48 h after injection), vehicle, edema and hydration of microparticles contributed to the signals. In the second (days 3-17) and third phases (day 17 onward), microparticle hydration was the main contributor. SOM230 in blood displayed peaks at days 2 and 17., Conclusion: MRI was suitable to follow longitudinally the presence of PLGA microparticles in the rat muscle without labeling them. This is advantageous, because labeling could potentially alter the properties and pharmacokinetics of the microparticles. Data were consistent with an initial compound release followed by diffusion and microparticle erosion as main mechanisms of SOM230 release., (© 2015 Wiley Periodicals, Inc.)

Introduction: The somatostatin receptor subtype sst2 is largely expressed on neuroendocrine tumors. However, current clinical studies indicate that the subtypes sst1, 3, 5 are of substantial relevance as well. Aim(s): We intend to develop a Ga-68-PET tracer covering a broad spectrum of ssts for clinical application. Materials and methods: The sst1, 2, 3, 5 highly specific SOM230 (Pasireotide) was coupled with the chelators DOTA or NODAGA and labeled with Ga-68. We investigated the tracers' sst-subtype binding and internalization profiles in vitro and the biodistribution and tumor uptake by microPET studies in hsst2- and hsst5-tumor xenografts. Results: Ga-68-DOTA-SOM230 revealed binding and internalization profiles comparable to SOM230. Both radiotracers clearly visualized hsst2- and hsstS-tumors in PET images with Ga-68- DOTA-SOM230 having higher tumor/non-tumor ratios. Specific tumor uptake was detected in hsst2-(Ga-68-DOTA-SOM230 14.1±4.5 and Ga-68-NODAGA-SOM230 13.8±5.7 %IA/g, respectively) and hsst5-tumors (11.4±1.3 and 8.7±1.8 %IA/g, respectively) 1h p.i. Relatively high blood pool activity was found (3.9±0.8 and 5.8±0.8 %IA/g, P<0.001, respectively) which was 2-fold reduced 2h p.i. Ga-68-DOTA-SOM230 had lower uptake in the kidney (30 v. 50 %IA/g, P<0.001) and similar in the liver (12 v. 14 %IA/g) than Ga-68-NODAGA-SOM230. Conclusion: Ga-68-DOTA-SOM230 (SOMscan*) seems to be a promising PET imaging agent to detect a broad spectrum of sst subtype receptors with considerable tumor/non-tumor ratios. [ABSTRACT FROM AUTHOR]

Measures to prevent breast cancer are receiving particular attention by women at high risk from either clinico-pathologic findings or genetic susceptibility. Life-style and nutritional interventions have been difficult to quantify, but merit further study. Chemoprevention with tamoxifen and subsequently with the related raloxifene demonstrates some efficacy, but may be not be applicable to premenopausal women (with regard to raloxifene), or have low acceptance (with regard to tamoxifen). Based on the importance of the insulin-like growth factor-1 pathway in mammary gland development, and the availability of a potent inhibitor, pilot studies are ongoing to evaluate such an inhibitor in women with demonstrable high risk to develop breast cancer. Short-term interventions with the inhibitor have been completed, and subsequent interventions are planned. [ABSTRACT FROM AUTHOR]

Cushing's disease is the most common cause of endogenous hypercortisolemia. It is a rare disease of unknown etiology that is prone to relapse and damaging to quality of life, even in remission. A significant proportion of patients are not cured by primary surgical treatment, and adjuvant radiotherapy has become an increasingly unattractive proposition for clinicians who wish to spare their patients hypopituitarism and other potential complications. The few effective pharmacological options that are available currently tend to have dose-limiting side effects and new alternatives that are safer and more effective than the adrenal cortical enzyme inhibitors and adrenolytic drugs would be most welcome. This article discusses preliminary efficacy data for several potential new groups of drugs.