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Abstract: Introduction: The aim of the study was to compare in vitro and in vivo a novel DOTA-chelated bombesin (BN) analog of the amino acid sequence, QRLGNQWAVGHLM-CONH2 (BN[2–14]NH2), labeled with 90Y and 177Lu, for its potential use in targeted radiotherapy of tumors expressing gastrin releasing peptide (GRP) receptors. The same amino acid sequence, but with different chelator, referred as BN1.1 (Gly-Gly-Cys-Aca-QRLGNQWAVGHLM-CONH 2 ), has already been studied and reported; however, the DOTA-chelated one, suitable for labeling with M+3 type radiometals, was not yet described. Methods: The conditions for labeling of DOTA-BN[2–14]NH2 with noncarrier added 90Y and with 177Lu [specific activity (SA), 15 Ci/mg Lu] were investigated and optimized to provide 90Y-DOTA-BN[2–14]NH2 and 177Lu-DOTA-BN[2–14]NH2 of high SA. The stability of the radiolabeled compounds in human serum was evaluated over a period of 24 h. The human prostate cancer cell line PC-3, known to express GRP receptors, was used for in vitro evaluation of radiolabeled peptide affinity to GRP receptors and for assessment of cytotoxicity of both nonlabeled and radiolabeled peptide. Biodistribution accompanied by receptor blocking was studied in normal Swiss mice. Results: 90Y-DOTA-BN[2–14]NH2 and 177Lu-DOTA-BN[2–14]NH2 were obtained with radiochemical yield >98% and high SA (67.3 GBq 90Y/μmol and 33.6 GBq 177Lu/μmol, respectively). They were stable when incubated in human serum for up to 24 h. The binding affinities of DOTA-BN[2–14]NH2 and both natY- and natLu-labeled analogs to GRP receptors were high (IC50=1.78, 1.99, and 1.34 nM, respectively), especially for the natLu-DOTA-BN[2–14]NH2 complex. The cytotoxicity study of DOTA-BN[2–14]NH2 to PC-3 cells revealed an IC50=6300 nM after 72 h of exposition, while the labeled derivatives showed no significant cytotoxic effect. The internalization rate to PC-3 cells was more rapid for 177Lu-labeled peptide (84.87%) than for the 90Y-labeled one (80.79%), while the efflux rate was slower for 177Lu-DOTA-BN[2–14]NH2 (46.8% vs. 61.74%). The biodistribution study of both derivatives in normal mice revealed a specific binding to GRP receptor-positive tissues, which could be blocked by coinjection of cold peptide. The effect of receptor blockage in vivo was also more pronounced for the 177Lu-labeled peptide than that for the 90Y-labeled (81% vs. 42%, respectively). Conclusions: Our studies demonstrated that DOTA-BN[2–14]NH2 can be labeled with 90Y (NCA) and 177Lu (CA) with high radiochemical yields. The in vitro and in vivo comparison between 90Y-DOTA-BN[2–14]NH2 and 177Lu-DOTA-BN[2–14]NH2 indicated that the change of radiometal in the complex from Y to Lu influence the binding affinity to the GRP receptors with preference to the 177Lu-labeled derivative. [Copyright &y& Elsevier]

Nuclear research reactors (RR) are essential facilities in countries implementing nuclear power plants and are used for experiments necessary for commercial reactor development, training and education programs, and many other applications not related to nuclear energy production (e.g., isotope production, neutron sources, materials science). Europe has a broad and very diverse landscape of RRs, many of which have been in operation for 30-60 years, are well maintained and regularly modernized. However, financial pressures caused by a combination of declining interest and the lack of a sound financial model have led to the closure of many of them (e.g. OSIRIS in Saclay, JEEP II research reactor at IFE Kjeller and BER2 in Berlin). These negative trends called for coordinated European action to assess the impact of the declining number of RRs. The Towards Optimized Use of Research Reactors (TOURR) project was a response to this challenge. Its main objective was to assess the status of the EU RR fleet and to develop a strategy for the refurbishment and construction of new RR in Europe. The assessment was based on analysed data obtained through extensive questionnaires sent to all operating European RR. The analysis revealed gaps in terms of lack of long-term funding, lack of manpower and lack of communication between RRs and their customers. It also showed threats of further European RR closures. Regarding the long-term EU RR strategy, the main recommendations of the TOURR project are to build (at least) two RRs, a medium-flux multipurpose reactor and a flexible zero-power facility. Both reactor cores could be part of a single facility built at the European level and accessible to all EU Member States. • Current status of the European Research Reactor fleet analysed. • Main gap in EU RR utilization is the lack of manpower and lack of financing. • RR research opportunities in new fields identified (e.g. processing of chemicals) • At least one new multipurpose medium-flux reactor is needed in EU. • In addition, results indicate the need for flexible zero-power reactor. [ABSTRACT FROM AUTHOR]

The information on the presence of cold metal complexes in radiolabeled DOTA-TATE or DOTA-TOC is important in assessing the cause of the radiolabeling failure, poor radiolabeling yield and/or low effective molar activity. DOTA-peptide complexes are detectable using UV–Vis detector. The main limitation in the quantitative analysis is the limited availability of standard substances and the lack of data on their molar absorption coefficients. The aim of our study was development and validation of HPLC method enabling RCP analysis and identification and quantification of metal complexes impurities in the radiopharmaceutical preparations of DOTA-chelated peptides. Complexes of DOTA-TATE and DOTA-TOC with several metals, were prepared. Their molar absorption coefficients at 220 nm were determined. The developed HPLC method has been validated in terms of quantitative determination of non-complexed DOTA-TATE and DOTA-TOC and their respective complexes with metallic individuals. Good chromatographic separation of the individual metal-DOTA-peptide complexes was achieved. The resolution between peaks of interest in radioactive preparations (complexes with: yttrium-90, lutetium-177, gallium-68) and metallic impurities was well above 1.5 (except gallium-68 DOTA-TOC preparations). Limits of detection and quantification were determined based on the parameters of the calibration curves. Based on the spectrophotometric and HPLC-DAD studies and statistical analysis of the results obtained, the average molar absorption coefficient was determined for studied DOTA-TATE and DOTA-TOC complexes, ε HPLC-DAD = 48 × 103M−1 cm−1. With the use of the determined molar absorption coefficient the method enabled quantitative determination of non-labelled peptide in the radioactive preparation in the linearity range of 0.5–100 μg/mL for DOTA-TATE(net) and 0.5–100 μg/mL for DOTA-TOC(net). The developed HPLC method is suitable for RCP determination of radiolabelled DOTA-TATE and DOTA-TOC preparations. Determination of the average molar absorption coefficient for DOTA-TATE and DOTA-TOC complexes allows assessment of the total content of the peptide in radiopharmaceutical preparation regardless of its chemical form (free ligand, associated with radionuclide, in the form of a complex with metal ions being the impurity) using the HPLC method with UV detection. [ABSTRACT FROM AUTHOR]

The method of 100 Mo metallic target preparation for production of 99m Tc by proton irradiation in 100 Mo(p,2 n) 99m Tc reaction was demonstrated. For this purpose, pressing of molybdenum powder into pellets and their subsequent sintering in reductive atmosphere were applied. The influence of parameters such as molybdenum mass and time of both pressing and sintering on the 100 Mo target durability was investigated. Under the optimized conditions, 100 Mo metallic pellet targets with density of 9.95±0.06 g/cm 3 were obtained. Morphology and structure of pressed pellets before and after sintering were studied by using standard optical microscope and Scanning Electron Microscope (SEM). Nanoindentation technique was used to investigate the mechanical properties such as nanohardness and Young modulus. Prepared 100 Mo pellets were successfully irradiated with protons and 99m Tc was efficiently isolated. [ABSTRACT FROM AUTHOR]

Introduction A variety of radiolabelled minigastrin analogues targeting the cholecystokinin 2 (CCK2) receptor were developed and compared in a concerted preclinical testing to select the most promising radiotracer for diagnosis and treatment of medullary thyroid carcinoma (MTC). DOTA–DGlu–DGlu–DGlu–DGlu–DGlu–DGlu–Ala–Tyr–Gly–Trp–Met–Asp–Phe–NH 2 (CP04) after labelling with 111 In displayed excellent characteristics, such as high stability, receptor affinity, specific and persistent tumour uptake and low kidney retention in animal models. Therefore, it was selected for further clinical evaluation within the ERA-NET project GRAN-T-MTC. Here we report on the development of a pharmaceutical freeze-dried formulation of the precursor CP04 for a first multi-centre clinical trial with 111 In-CP04 in MTC patients. Materials and methods The kit formulation was optimised by adjustment of buffer, additives and radiolabelling conditions. Three clinical grade batches of a final kit formulation with two different amounts of peptide (10 or 50 μg) were prepared and radiolabelled with 111 In. Quality control and stability assays of both the kits and the resulting radiolabelled compound were performed by HPLC analysis. Results Use of ascorbic acid buffer (pH 4.5) allowed freeze-drying of the kit formulation with satisfactory pellet-formation. Addition of methionine and gentisic acid as well as careful selection of radiolabelling temperature was required to avoid extensive oxidation of the Met 11 -residue. Trace metal contamination, in particular Zn, was found to be a major challenge during the pharmaceutical filling process in particular for the 10 μg formulation. The final formulations contained 10 or 50 μg CP04, 25 mg ascorbic acid, 0.5 mg gentisic acid and 5 mg l -methionine. The radiolabelling performed by incubation of 200–250 MBq 111 InCl 3 at 90 °C for 15 min resulted in reproducible radiochemical purity (RCP) > 94%. Kit-stability was proven for > 6 months at + 5 °C and at + 25 °C. The radiolabelled product was stable for > 4 h at + 25 °C. Conclusion A kit formulation to prepare 111 In-CP04 for clinical application was developed, showing high stability of the kit as well as high RCP of the final product. [ABSTRACT FROM AUTHOR]

Abstract: Purpose: PRRT is a known tool in the management of patients with disseminated and inoperable NETs. The aim of study was to assess the effectiveness of the repeated cycles of PRRT in patients with disseminated and inoperable NETs. Material and methods: Eighty nine patients were included in the PRRT. Among them 16 patients (18%) were qualified for a repeated PRRT cycle due to progression of the disease. In one of the patients qualified for the repeated cycle, PRRT was used as neoadjuvant therapy. The results and side-effects of the repeated cycles of PRRT were analyzed. Results: Disease stabilization was observed in 10 patients 6months after the repeated PRRT cycle and in 5 patients after 12 and 18months. Ten of the patients who had received repeated PRRT cycles died. In the case of neoadjuvant therapy, further reduction of the tumor size was observed, enabling qualification for surgery. Clinically significant reduction in the mean values of morphological parameters was not observed. Only after 12 and 18months the mean values of creatinine levels were higher than the normal range (only in 2 patients). Conclusions: The repeated cycles of PRRT did not cause a clinically significant increase of the toxicity of PRRT. The changes in kidney and blood morphology parameters were transient. The repeated cycles of PRRT enabled stabilization of the disease. [Copyright &y& Elsevier]

Abstract: Introduction: Interleukin-2 (IL-2) when radiolabelled with 99mTc has been proved useful in imaging the side of lymphocytic infiltration in patients with autoimmune disorders and plays a significant role as a T-cell imaging agent. However, the labelling procedures used so far appeared to be rather complex and laborious. The aim of present study was to develop an efficient procedure of 99mTc-labelling of recombinant human interleukin-2 (rhIL-2) via hydrazinonicotinamide (HYNIC) to develop a dry kit formulation. Methods: Various molar ratios of rhIL-2/HYNIC (from 1:2 to 1:12) were used at the conjugation step. The conjugates were purified on a PD-10 column to remove the excess of unbound HYNIC, as well as of any aggregates. The final peptide concentration was quantified by the BCA method, and the number of HYNIC molecules incorporated into a rhIL-2 molecule was determined based on the reaction with 2-sulfobenzaldehyde. The 99mTc-labelling was optimized using various amounts of HYNIC–rhIL-2, 99mTc, SnCl2, tricine and nicotinic acid (NA). Quality control included GF-HPLC, ITLC, SDS-PAGE and biological assay. Biodistribution studies were performed in Swiss mice and Wistar rats. Results: Generally, the highest radiolabelling yields were achieved when the HYNIC–rhIL-2 conjugates of ca. 2–4 HYNIC molecule substitution ratios were used. The optimal pH of the reaction medium was found to be in the range of 6.5 to 7.0. GF-HPLC analysis indicated that monomer and aggregates of 99mTc-HYNIC–rhIL-2 are formed during radiolabelling. At optimized conditions of wet radiolabelling, the 99mTc-HYNIC–rhIL-2 monomer was obtained with radiochemical purity >99%, specific activity of ca. 4 GBq/mg rhIL-2 and overall yield of ca. 65%. The two-vial freeze-dried kit was prepared: the first vial contained 30 μg HYNIC–rhIL-2, co-ligands, buffer and antioxidant; the second vial contained tricine and SnCl2. The monomer of 99mTc-HYNIC–rhIL-2 was obtained by gel chromatography on a PD-10 column. No differences between labelled and unlabelled IL2 in terms of biological activity were observed. Conclusions: Our study shows that rhIL-2 can be efficiently radiolabelled with 99mTc via HYNIC, with tricine and NA as co-ligands using a two-vial freeze-dried kit. This enables the preparation of sterile and ready-to-use 99mTc-HYNIC(tricine,NA)-rhIL-2 within 1 h. [Copyright &y& Elsevier]