Efficacy and safety of pasireotide for Cushing's disease: A protocol for systematic review and meta-analysis.

BACKGROUND: Cushing's disease (CD) is associated with increased risk of mortality, myocardial infarction, stroke, peptic ulcers, fractures and infections. The prevalence of CD is nearly 40 per million and higher in women than in men. When surgery has failed, is not feasible, or has been refused, pharmacotherapy can be considered a valuable option. Pasireotide is the first medical therapy officially approved for adult patients with CD. We will conduct a comprehensive systematic review and meta-analysis to systematically evaluate the efficacy and safety of pasireotide for CD. METHODS: Five English databases (PubMed, Web of Science, Embase, Cochrane Library, and OVID) and 3 Chinese databases (China National Knowledge Infrastructure, China Science and Technology Journal Database, and Chinese Biomedical Literature Database) will be searched from their respective inception of databases to December 2020. Two reviewers will select articles, extract data and assess the risk of bias independently. Any disagreement will be resolved by discussion with the third reviewer. Review Manager 5.3 software will be used for data synthesis. The Cochrane risk of bias assessment tool will be used to evaluate the bias risk. RESULTS: This systematic review and meta-analysis will conduct a comprehensive literature search and provide a systematic synthesis of current published data to explore the efficacy and safety of pasireotide for CD. CONCLUSIONS: This systematic review and meta-analysis will provide clinical evidence for the efficacy and safety of pasireotide for CD, and inform our understanding of the value of pasireotide in improving CD clinical signs and symptoms. The conclusions drawn from this study may be beneficial to patients, clinicians, and health-related policy makers. STUDY REGISTRATION NUMBER: INPLASY2020110070.

A new method for the radiochemical purity measurement of ¹¹¹In-pentetreotide.

OBJECTIVES AND METHODS: The recommended method for the measurement of radiochemical purity (RCP) of ¹¹¹In-labelled pentetreotide is thin-layer chromatography with a silica gel as the stationary phase and a 0.1 N sodium citrate solution (pH 5) as the mobile phase. According to the supplier's instructions, the mobile phase must be prepared before the test is carried out, and the recommended stationary phase is off-market. We propose a new method for RCP measurement in which the mobile phase is acid citrate dextrose, solution A, which does not need to be prepared beforehand, and thin-layer chromatography is performed with a silica gel-impregnated glass fibre sheet as the stationary phase. We used both methods to measure the percentages of radiopharmaceutical and impurities. RESULTS: The range of RCP values obtained was 98.0-99.9% (mean=99.3%) by the standard method and 98.1-99.9% (mean=99.2%) by the new method. We observed no differences between the RCP values of both methods (P=0.070). CONCLUSION: The proposed method is suitable for RCP testing because it yields results that are in good agreement with those of the standard method and because it is easier to perform as the mobile-phase solution need not be prepared in advance.

A calibration method that simplifies and improves accurate determination of peptide molecular masses by MALDI-TOF MS.

The use of delayed ion extraction in MALDI time-of-flight mass spectrometry distorts the linear relationship between m/z and the square of the ion flight time (t2) with the consequence that, if a mass accuracy of 10 ppm or better is to be obtained, the calibrant signals have to fall close to the analyte signals. If this is not possible, systematic errors arise. To eliminate these, a higher-order calibration function and thus several calibrant signals are required. For internal calibration, however, this approach is limited by signal suppression effects and the increasing chance of the calibrant signals overlapping with analyte signals. If instead the calibrants are prepared separately, this problem is replaced by an other; i.e., the ion flight times are dependent on the sample plate position. For this reason, even if the calibrants are placed close to the sample, the mass accuracy is not improved when a higher-order calibration function is applied. We have studied this phenomenon and found that the relative errors, which result when moving from one sample to the next, are directly proportional to m/z. Based on this observation, we developed a two-step calibration method, that overcomes said limitations. The first step is an external calibration with a high-order polynomial function used for the determination of the relation between m/z and t2, and the second step is a first-order internal correction for sample position-dependent errors. Applying this method, for instance, to a mass spectrum of a mixture of 18 peptides from a tryptic digest of a recombinant protein resulted in an average mass error of 1.0 ppm with a standard deviation of 3.5 ppm. When instead using a conventional two-point internal calibration, the average relative error was 2.2 ppm with a standard deviation of 15 ppm. The new method is described and its performance is demonstrated with examples relevant to proteome research.

Labeling and quality control of 188Re-lanreotide.

Lanreotide was labelled with 188Re obtained from 188W/188Re generator, using stannous ion as reducing agent, ascorbic acid as stabilizers and hydroxy ethylidene bisphosphonate (HEDP) as intermediary ligand at different molar ratios, pH and incubation times. Best yields (>95%) were obtained using molar ratios SnF2/lanreotide, ascorbic/lanreotide and HEDP/lanreotide of 40, 12 and 260, respectively, pH 1-2 with an incubation at 100 degrees C for 30 min. Quality control evaluation and stability of the radiolabel compound was done by the following selected methods: chromatography in Whatman 3 MM with MEK and NaCl 0.15 M as solvents, ITLC-SG with ethanol-HCl 0.01N (90:10); reverse phase extraction cartridge (Sep-pak C18, Waters Associated) and RP-HPLC with radiometric and UV detection (220 nm) using MCH-5 n-capp column with linear gradient from 90% H2O (TFA 0.1%): 10% ACN (TFA 0.1%) up to 10% H2O (TFA 0.1%):90% ACN (TFA 0.1%) in 30 min, at flow 1 ml/min. Biodistribution in normal mice showed that 188Re-lanreotide is excreted mainly through the hepatobiliary system: more than 70% I.D. is present in gallbladder and intestines at 2 hr post injection. The stability of the 188Re-peptide bond by cysteine challenge test at 37 degrees C, during 2 and 24 hr of incubation time, reveals that approximately 300 and 100 molar ratio cys/peptide is required to displace 50% of the 188Re from the complex. In vitro stability of 188Re-lanreotide at room temperature (Rt) was demonstrated during 24 hr Future works must be done in order to investigate its binding capacity to somatostatin receptors.