[111In]In-CP04 as a novel cholecystokinin-2 receptor ligand with theranostic potential in patients with progressive or metastatic medullary thyroid cancer: final results of a GRAN-T-MTC Phase I clinical trial.

INTRODUCTION: Medullary thyroid cancer (MTC) is a rare malignant tumour of the parafollicular C-cells with an unpredictable clinical course and currently suboptimal diagnostic and therapeutic options, in particular in advanced disease. Overexpression of cholecystokinin-2 receptors (CCK2R) represents a promising avenue to diagnostic imaging and targeted therapy, ideally through a theranostic approach. MATERIALS AND METHODS: A translational study (GRAN-T-MTC) conducted through a Phase I multicentre clinical trial of the indium-111 labelled CP04 ([111In]In-CP04), a CCK2R-seeking ligand was initiated with the goal of developing a theranostic compound. Patients with proven advanced/metastatic MTC or short calcitonin doubling time were enrolled. A two-step concept was developed through the use of low- and high-peptide mass (10 and 50 µg, respectively) for safety assessment, with the higher peptide mass considered appropriate for therapeutic application. Gelofusine was co-infused in a randomized fashion in the second step for the evaluation of potential reduction of the absorbed dose to the kidneys. Imaging for the purpose of biodistribution, dosimetry evaluation, and diagnostic assessment were performed as well as pre-, peri-, and postprocedural clinical and biochemical assessment. RESULTS: Sixteen patients were enrolled. No serious adverse events after application of the compound at both peptide amounts were witnessed; transient tachycardia and flushing were observed in two patients. No changes in biochemistry and clinical status were observed on follow-up. Preliminary dosimetry assessment revealed the highest dose to urinary bladder, followed by the kidneys and stomach wall. The effective dose for 200 MBq of [111In]In-CP04 was estimated at 7±3 mSv and 7±1 mSv for 10 µg and 50 µg CP04, respectively. Administration of Gelofusine reduced the dose to the kidneys by 53%, resulting in the organ absorbed dose of 0.044±0.019 mSv/MBq. Projected absorbed dose to the kidneys with the use of [177Lu]Lu-CP04 was estimated at 0.9±0.4 Gy/7.4 GBq. [111In]In-CP04 scintigraphy was positive in 13 patients (detection rate of 81%) with superior diagnostic performance over conventional imaging. CONCLUSION: In the present study, [111In]In-CP04 was shown to be a safe and effective radiopharmaceutical with promising theranostic characteristics for patients with advanced MTC.

67Cu Production Capabilities: A Mini Review.

Is the 67Cu production worldwide feasible for expanding preclinical and clinical studies? How can we face the ingrowing demands of this emerging and promising theranostic radionuclide for personalized therapies? This review looks at the different production routes, including the accelerator- and reactor-based ones, providing a comprehensive overview of the actual 67Cu supply, with brief insight into its use in non-clinical and clinical studies. In addition to the most often explored nuclear reactions, this work focuses on the 67Cu separation and purification techniques, as well as the target material recovery procedures that are mandatory for the economic sustainability of the production cycle. The quality aspects, such as radiochemical, chemical, and radionuclidic purity, with particular attention to the coproduction of the counterpart 64Cu, are also taken into account, with detailed comparisons among the different production routes. Future possibilities related to new infrastructures are included in this work, as well as new developments on the radiopharmaceuticals aspects.

Design and Evaluation of 223Ra-Labeled and Anti-PSMA Targeted NaA Nanozeolites for Prostate Cancer Therapy-Part II. Toxicity, Pharmacokinetics and Biodistribution.

Metastatic castration-resistant prostate cancer (mCRPC) is a progressive and incurable disease with poor prognosis for patients. Despite introduction of novel therapies, the mortality rate remains high. An attractive alternative for extension of the life of mCRPC patients is PSMA-based targeted radioimmunotherapy. In this paper, we extended our in vitro study of 223Ra-labeled and PSMA-targeted NaA nanozeolites [223RaA-silane-PEG-D2B] by undertaking comprehensive preclinical in vitro and in vivo research. The toxicity of the new compound was evaluated in LNCaP C4-2, DU-145, RWPE-1 and HPrEC prostate cells and in BALB/c mice. The tissue distribution of 133Ba- and 223Ra-labeled conjugates was studied at different time points after injection in BALB/c and LNCaP C4-2 tumor-bearing BALB/c Nude mice. No obvious symptoms of antibody-free and antibody-functionalized nanocarriers cytotoxicity and immunotoxicity was found, while exposure to 223Ra-labeled conjugates resulted in bone marrow fibrosis, decreased the number of WBC and platelets and elevated serum concentrations of ALT and AST enzymes. Biodistribution studies revealed high accumulation of 223Ra-labeled conjugates in the liver, lungs, spleen and bone tissue. Nontargeted and PSMA-targeted radioconjugates exhibited a similar, marginal uptake in tumour lesions. In conclusion, despite the fact that NaA nanozeolites are safe carriers, the intravenous administration of NaA nanozeolite-based radioconjugates is dubious due to its high accumulation in the lungs, liver, spleen and bones.

PSMA-D4 Radioligand for Targeted Therapy of Prostate Cancer: Synthesis, Characteristics and Preliminary Assessment of Biological Properties.

A new PSMA ligand (PSMA-D4) containing the Glu-CO-Lys pharmacophore connected with a new linker system (L-Trp-4-Amc) and chelator DOTA was developed for radiolabeling with therapeutic radionuclides. Herein we describe the synthesis, radiolabeling, and preliminary biological evaluation of the novel PSMA-D4 ligand. Synthesized PSMA-D4 was characterized using TOF-ESI-MS, NMR, and HPLC methods. The novel compound was subject to molecular modeling with GCP-II to compare its binding mode to analogous reference compounds. The radiolabeling efficiency of PSMA-D4 with 177Lu, 90Y, 47Sc, and 225Ac was chromatographically tested. In vitro studies were carried out in PSMA-positive LNCaP tumor cells membranes. The ex vivo tissue distribution profile of the radioligands and Cerenkov luminescence imaging (CLI) was studied in LNCaP tumor-bearing mice. PSMA-D4 was synthesized in 24% yield and purity >97%. The radio complexes were obtained with high yields (>97%) and molar activity ranging from 0.11 to 17.2 GBq mcmol-1, depending on the radionuclide. In vitro assays confirmed high specific binding and affinity for all radiocomplexes. Biodistribution and imaging studies revealed high accumulation in LNCaP tumor xenografts and rapid clearance of radiocomplexes from blood and non-target tissues. These render PSMA-D4 a promising ligand for targeted therapy of prostate cancer (PCa) metastases.

Tandem peptide receptor radionuclide therapy using 90Y/177Lu-DOTATATE for neuroendocrine tumors efficacy and side-effects - polish multicenter experience.

INTRODUCTION: One of the concepts of theranostics in nuclear medicine is peptide receptor radionuclide therapy (PRRT), whereby labeled somatostatin analogs are used for imaging and treating inoperable or disseminated neuroendocrine tumors (NET). AIM: The aim of the study was to determine the therapeutic efficacy and toxicity of tandem 90Y /177Lu-DOTATATE in patients with disseminated NET in a multicenter trial. MATERIALS AND METHODS: 103 patients with NET G1/G2 treated with 90Y/177Lu-DOTATATE (1:1) with amino-acid infusion for nephroprotection were included in the study. RESULTS: Overall survival from the disease diagnosis (OS-D) was 127.4 months and from the time of PRRT (OS-T) was 89.5 months. Progression-free survival (PFS) was 29.9 months. An analysis based on the proliferation index revealed a statistically significant impact on PFS and OS-T (PFS G1 vs G2, 59.3 vs 24.3 months; OS-T G1 vs G2, not reached vs 79.9 months). The effect of the primary disease site was also analyzed. For pancreatic vs small bowel vs large bowel, the PFS was 30.8 vs 30.3 vs 40.6 months, the OS-T was 94 vs 61.9 vs 131.2 months and OS-D was 130.4 vs 89.2 vs not reached months, respectively. The 2-year risk of progression was 42%. The probability of 2-year and 5-year overall survival was 89% and 62%, respectively. PRRT was well tolerated by all patients. One patient (1%) developed myelodysplastic syndrome. No other grade 3 and 4 hematological or renal toxicity was observed. CONCLUSIONS: This multicenter trial showed that tandem 90Y/177Lu-DOTATATE is highly effective and safe therapy for patients with disseminated NET.

Radiometals for imaging and theranostics, current production, and future perspectives.

The aim of this review is to make the reader familiar with currently available radiometals, their production modes, capacities, and quality concerns related to their medical use, as well as new emerging radiometals and irradiation technologies from the perspective of their diagnostic and theranostic applications. Production methods of 177 Lu serve as an example of various issues related to the production yield, specific activity, radionuclidic and chemical purity, and production economy. Other radiometals that are currently used or explored for potential medical applications, with particular focus on their theranostic value, are discussed. Using radiometals for diagnostic imaging and therapy is on the rise. The high demand for radiometals for medical use prompts investigations towards using alternative irradiation reactions, while using existing nuclear reactors and accelerator facilities. This review discusses these production capacities and what is necessary to cover the growing demand for theranostic nuclides.

Clinical translation of theranostic radiopharmaceuticals: Current regulatory status and recent examples.

With the development of ever more radiopharmaceuticals suitable for theranostic applications, translation of novel compounds from the preclinical stage towards clinical application becomes a bottleneck for the advances in Nuclear Medicine. This review article summarizes the current regulatory framework for clinical trials with radiopharmaceuticals in the European Union, provides a general overview of the documentation required, and addresses quality, safety, and clinical aspects to be considered. By using a recent successful example of translating a theranostic peptide radioligand, namely 111 In-CP04, which targets receptors expressed in medullary thyroid carcinoma, the pathway from the preclinical development over establishing the required pharmaceutical documentation to designing and submitting a clinical trial is reviewed. Details regarding preclinical data, generation of the documentation, and final successful application are described. This article should provide an insight in an ever more complex process to bring innovations in the field of radiopharmaceuticals into patients.

177Lu Labeled Cyclic Minigastrin Analogues with Therapeutic Activity in CCK2R Expressing Tumors: Preclinical Evaluation of a Kit Formulation.

Minigastrin (MG) analogues specifically target cholecystokinin-2 receptors (CCK2R) expressed in different tumors and enable targeted radiotherapy of advanced and disseminated disease when radiolabeled with a beta emitter such as 177Lu. Especially truncated MG analogues missing the penta-Glu sequence are associated with low kidney retention and seem therefore most promising for therapeutic use. Based on [d-Glu1,desGlu2-6]MG (MG11) we have designed the two cyclic MG analogues cyclo1,9[γ-d-Glu1,desGlu2-6,d-Lys9]MG (cyclo-MG1) and cyclo1,9[γ-d-Glu1,desGlu2-6,d-Lys9,Nle11]MG (cyclo-MG2). In the present work we have developed and preclinically evaluated a pharmaceutical kit formulation for the labeling with 177Lu of the two DOTA-conjugated cyclic MG analogues. The stability of the kits during storage as well as the stability of the radiolabeled peptides was investigated. A cell line stably transfected with human CCK2R and a control cell line without receptor expression were used for in vitro and in vivo studies with the radioligands prepared from kit formulations. In terms of stability 177Lu-DOTA-cyclo-MG2 showed advantages over 177Lu-DOTA-cyclo-MG1. Still, for both radioligands a high receptor-mediated cell uptake and favorable pharmacokinetic profile combining receptor-specific tumor uptake with low unspecific tissue uptake and low kidney retention were confirmed. Investigating the therapy efficacy and treatment toxicity in xenografted BALB/c nude mice a receptor-specific and comparable therapeutic effect could be demonstrated for both radioligands. A 1.7- to 2.6-fold increase in tumor volume doubling time was observed for receptor-positive tumors in treated versus untreated animals, which was 39-73% higher when compared to receptor-negative tumors. The treatment was connected with transient bone marrow toxicity and minor signs of kidney toxicity. All together the obtained results support further studies for the clinical translation of this new therapeutic approach.

A one-step automated synthesis of the dopamine transporter ligand [(18)F]FECNT from the chlorinated precursor.

The use of [(18)F]labelled nortropane derivative 2ß-carbomethoxy-3ß-(4-chlorophenyl)-8-(2-fluoroethyl)-nortropane (FECNT) as a dopamine transporter ligand for PET imaging is dependent on efficient radiosynthesis method. Herein, the automated synthesis of [(18)F]FECNT from its chlorinated precursor in commercially available SynChrom [(18)F] R&D module has been developed. The synthesis unit was readily configured for the one-step synthesis from corresponding chlorinated precursor. The radiolabeling process involved a classical [(18)F]fluoride nucleophilic substitution performed at 110 °C for 12 min and finally HPLC and SPE purification. Crude [(18)F]FECNT was obtained with a radiolabeling yield of 59 ± 12% (n = 5). The average uncorrected amount of [(18)F]FECNT in the final formulated dose was 2.0 ± 0.5 GBq (32 ± 7% overall decay-corrected yields) obtained with radiochemical purity over 99% and specific activity of 55 GBq/µmol. The total duration of the procedure was 80-90 min. An automated radiosynthesis of [(18)F]FECNT with high radiochemical purity may provide a simple and robust method of radiopharmaceutical preparation for routine clinical applications.

Initial study of radiological and clinical efficacy radioembolization using 188Re-human serum albumin (HSA) microspheres in patients with progressive, unresectable primary or secondary liver cancers.

BACKGROUND: The aim of this initial study was to evaluate the clinical and radiological effectiveness of radioembolization (RE) using 188Re-Human Serum Albumin (HSA) microspheres in patients with advanced, progressive, unresectable primary or secondary liver cancers, not suitable to any other form of therapy. MATERIAL/METHODS: Overall, we included 13 patients with 20 therapy sessions. Clinical and radiological responses were assessed at 6 weeks after therapy, and then every 3 months. The objective radiological response was classified according to Response Evaluation Criteria in Solid Tumors (RECIST) v.1.0 by sequential MRI. Adverse events were evaluated using NCI CTCAE v.4.03. RESULTS: There were 4 patients with hepatocellular carcinoma (HCC), 6 with metastatic colorectal cancer (mCRC), 2 with neuroendocrine carcinoma (NEC), and 1 patient with ovarian carcinoma. Mean administered activity of 188Re HSA was 7.24 GBq (range 3.8-12.4) A high microspheres labeling efficacy of over 97±2.1% and low urinary excretion of 188Re (6.5±2.3%) during first 48-h follow-up. Median overall survival (OS) for all patients was 7.1 months (CI 6.2-13.3) and progression-free survival (PFS) was 5.1 months (CI 2.4-9.9). In those patients who had a clinical partial response (PR), stable disease (SD), and disease progression (DP) as assessed 6 weeks after therapy, the median OS was 9/5/4 months, respectively, and PFS was 5/2/0 months, respectively. The treatment adverse events (toxicity) were at an acceptable level. Initially and after 6 weeks, the CTC AE was grade 2, while after 3 months it increased to grade 3 in 4 subjects. This effect was mostly related to rapid cancer progression in this patient subgroup. CONCLUSIONS: The results of this preliminary study indicate that RE using 188Re HSA is feasible and a viable option for palliative therapy in patients with extensive progressive liver cancer. It was well tolerated by most patients, with a low level of toxicity during the 3 months of follow-up.

Glucagon-like peptide-1 receptor imaging with [Lys40(Ahx-HYNIC- 99mTc/EDDA)NH2]-exendin-4 for the detection of insulinoma.

PURPOSE: The objective of this article is to present a new method for the diagnosis of insulinoma with the use of [Lys(40)(Ahx-HYNIC-(99m)Tc/EDDA)NH2]-exendin-4. METHODS: Studies were performed in 11 patients with negative results of all available non-isotopic diagnostic methods (8 with symptoms of insulinoma, 2 with malignant insulinoma and 1 with nesidioblastosis). In all patients glucagon-like peptide-1 (GLP-1) receptor imaging (whole-body and single photon emission computed tomography/CT examinations) after the injection of 740 MBq of the tracer was performed. RESULTS: Both sensitivity and specificity of GLP-1 receptor imaging were assessed to be 100 % in patients with benign insulinoma. In all eight cases with suspicion of insulinoma a focal uptake in the pancreas was found. In six patients surgical excision of the tumour was performed (type G1 tumours were confirmed histopathologically). In one patient surgical treatment is planned. One patient was disqualified from surgery. In one case with malignant insulinoma pathological accumulation of the tracer was found only in the region of local recurrence. The GLP-1 study was negative in the other malignant insulinoma patient. In one case with suspicion of nesidioblastosis, a focal accumulation of the tracer was observed and histopathology revealed coexistence of insulinoma and nesidioblastosis. CONCLUSION: [Lys(40)(Ahx-HYNIC-(99m)Tc/EDDA)NH2]-exendin-4 seems to be a promising diagnostic tool in the localization of small insulinoma tumours, but requires verification in a larger series of patients.

Polish experience in Peptide receptor radionuclide therapy.

PATIENTS AND METHODS: During the period from April 2004 to December 2010, 358 patients underwent peptide receptor radionuclide therapy (PRRT) ((90)Y-DOTATATE, (177)Lu-DOTATATE, and (90)Y/(177)Lu-DOTATATE) in Poland. RESULTS: The majority of patients underwent (90)Y-DOTATATE therapy (n = 177) with progression-free survival (PFS)/time to progression (TTP) of 17-44 months and overall survival (OS) of 22-34.2 months. Twelve-month follow-up revealed stable disease (SD) in 46-60%, disease regression (RD) in 16-35%, disease progression (PD) in 7-17%, and complete remission (CR) in 3% of patients. In patients treated with (90)Y/(177)Lu-DOTATATE (n = 44), PFS/TTP was 24.2-28.3 months and OS was 49.8-52.8 months. Twelve-month follow-up showed SD in 62-70%, RD in 15-20%, and PD in 10-12% of patients. The treatment was well tolerated. No severe adverse events occurred. Grade 3 toxicity [in leucocytes (WBC) and thrombocytes (PLT)] was seen in 6-20% of patients treated with (90)Y-DOTATATE. In that group, renal toxicity grade 3 was seen in 5-12% and grade 4 in 3-8%. In patients treated with tandem therapy with (90)Y/(177)Lu-DOTATATE or (177)Lu-DOTATATE alone, hematological and renal toxicity grade 3 or 4 was not observed. CONCLUSIONS: The results indicate that PRRT with the procedures and isotopes used is an effective and safe therapy option for patients with metastatic or inoperable neuroendocrine tumors (NETs). Our results suggest that tandem therapy with (90)Y/(177)Lu-DOTATATE provides longer overall survival than single-isotope treatment. Hematological toxicity was rare in all treated patients. Renal toxicity grade 3 and 4 was observed only in the group treated with (90)Y-DOTATATE.

Development of the 99mTc-Labelled SST2 Antagonist TECANT-1 for a First-in-Man Multicentre Clinical Study.

Broad availability and cost-effectiveness of 99Mo/99mTc generators worldwide support the use, and thus the development, of novel 99mTc-labelled radiopharmaceuticals. In recent years, preclinical and clinical developments for neuroendocrine neoplasms patient management focused on somatostatin receptor subtype 2 (SST2) antagonists, mainly due to their superiority in SST2-tumour targeting and improved diagnostic sensitivity over agonists. The goal of this work was to provide a reliable method for facile preparation of a 99mTc-labelled SST2 antagonist, [99mTc]Tc-TECANT-1, in a hospital radiopharmacy setting, suitable for a multi-centre clinical trial. To ensure successful and reproducible on-site preparation of the radiopharmaceutical for human use shortly before administration, a freeze-dried three-vial kit was developed. The final composition of the kit was established based on the radiolabelling results obtained during the optimisation process, in which variables such as precursor content, pH and buffer, as well as kit formulations, were tested. Finally, the prepared GMP-grade batches met all predefined specification parameters together with long-term kit stability and stability of the product [99mTc]Tc-TECANT-1. Furthermore, the selected precursor content complies with micro-dosing, based on an extended single-dose toxicity study, where histopathology NOEL was established at 0.5 mg/kg BW, being more than 1000 times higher than the planned human dose of 20 µg. In conclusion, [99mTc]Tc-TECANT-1 is suitable to be advanced into a first-in-human clinical trial.

Imaging of inflamed carotid artery atherosclerotic plaques with the use of 99mTc-HYNIC-IL-2 scintigraphy in end-stage renal disease patients.

PURPOSE: Identification of vulnerable plaques remains crucial for better cardiovascular risk assessment. At least 20% of inflammatory cells within unstable (vulnerable) plaques comprise T lymphocytes, which contain receptors for interleukin-2 (IL-2); those receptors can be identified by scintigraphy with radiolabelled IL-2.The aim of this study was to identify the "inflamed" (vulnerable) plaques by scintigraphy using IL-2 labelled with (99m)Tc in the selected, high cardiovascular risk group of end-stage renal disease (ESRD) patients. METHODS: A total of 28 patients (18 men, 10 women, aged 55.2 ± 9.6 years, 17 on peritoneal dialysis, 11 on haemodialysis) underwent common carotid artery (CCA) scintigraphy with the use of (99m)Tc-hydrazinonicotinamide (HYNIC)-IL-2. In all cases, ultrasound examination of the CCA was performed and levels of selected proinflammatory factors, atherogenic markers and calcium-phosphate balance parameters were measured. Finally, the target to non-target (T/nT) ratio of IL-2 uptake in atherosclerotic plaques with intima-media thickness (IMT), classic cardiovascular risk factors and concentrations of the measured factors were compared. RESULTS: Increased (99m)Tc-HYNIC-IL-2 uptake in atherosclerotic plaques in 38/41 (91%) cases was detected. The median T/nT ratio of focal (99m)Tc-HYNIC-IL-2 uptake in atherosclerotic plaques was 2.35 (range 1.23-3.63). The mean IMT value on the side of plaques assessed by scintigraphy was 0.79 ± 0.18 mm (median 0.8, range 0.5-1.275). Correlations between T/nT ratio and homocysteine (R = 0.22, p = 0.037), apolipoprotein B (apoB) (R = 0.31, p = 0.008), apoB to apoA-I ratio (R = 0.29, p = 0.012) and triglyceride concentration (R = 0.26, p = 0.021) were detected. A lower T/nT ratio in patients with better parameters of nutritional status (haemoglobin, albumin, adiponectin) in comparison with patients with worse nutritional parameters (3.20 ± 0.5 vs 2.16 ± 0.68, p = 0.025) was revealed as well as a difference between values of T/nT ratio in groups of patients with values of apoB, soluble CD40 ligand and asymmetric dimethylarginine above and below median (3.18 ± 0.52 vs 2.16 ± 0.68, p = 0.031). No statistically significant association was found between T/nT ratio and mean value of either IMT or classic cardiovascular risk factors. CONCLUSION: Scintigraphy with the use of (99m)Tc-HYNIC-IL-2 can be a tool for inflamed atherosclerotic (vulnerable) plaque visualization within CCA in ESRD patients. Quantitative results of carotid artery scintigraphy with (99m)Tc-HYNIC-IL-2 correlate with serum concentration of selected cardiovascular risk markers.

Bioorthogonal Chemistry Approach for the Theranostics of GRPR-Expressing Cancers.

Several gastrin-releasing peptide receptor (GRPR) antagonists with improved in vivo behavior have been recently developed and tested in the clinic. However, despite the generally mild side effects of peptide receptor radionuclide therapy (PRRT), toxicity has been observed due to high doses delivered to nontarget tissues, especially in the kidneys and pancreas. Previous experiences with radiolabeled peptides opened a unique opportunity to explore GRPR pretargeting using clickable bombesin antagonists. Toward this goal, we used clickable DOTA-like radiocomplexes which have been previously evaluated by our group. We functionalized a potent GRPR antagonist with a clickable TCO moiety using two different linkers. These precursors were then studied to select the compound with the highest GRPR binding affinity and the best pharmacokinetics to finally explore the advantages of the devised pretargeting approach. Our results provided an important proof of concept toward the development of bioorthogonal approaches to GRPR-expressing cancers, which are worth investigating further to improve the in vivo results. Moreover, the use of clickable GRPR antagonists and DOTA/DOTAGA derivatives allows for fine-tuning of their pharmacokinetics and metabolic stability, leading to a versatile synthesis of new libraries of (radio)conjugates useful for the development of theranostic tools toward GRPR-expressing tumors.

Practical considerations for navigating the regulatory landscape of non-clinical studies for clinical translation of radiopharmaceuticals.

BACKGROUND: The development of radiopharmaceuticals requires extensive evaluation before they can be applied in a diagnostic or therapeutic setting in Nuclear Medicine. Chemical, radiochemical, and pharmaceutical parameters must be established and verified to ensure the quality of these novel products. MAIN BODY: To provide supportive evidence for the expected human in vivo behaviour, particularly related to safety and efficacy, additional tests, often referred to as "non-clinical" or "preclinical" are mandatory. This document is an outcome of a Technical Meeting of the International Atomic Energy Agency. It summarises the considerations necessary for non-clinical studies to accommodate the regulatory requirements for clinical translation of radiopharmaceuticals. These considerations include non-clinical pharmacology, radiation exposure and effects, toxicological studies, pharmacokinetic modelling, and imaging studies. Additionally, standardisation of different specific clinical applications is discussed. CONCLUSION: This document is intended as a guide for radiopharmaceutical scientists, Nuclear Medicine specialists, and regulatory professionals to bring innovative diagnostic and therapeutic radiopharmaceuticals into the clinical evaluation process in a safe and effective way.

Highlight selection of radiochemistry and radiopharmacy developments by editorial board.

BACKGROUND: The Editorial Board of EJNMMI Radiopharmacy and Chemistry releases a biannual highlight commentary to update the readership on trends in the field of radiopharmaceutical development. MAIN BODY: This commentary of highlights has resulted in 21 different topics selected by each coauthoring Editorial Board member addressing a variety of aspects ranging from novel radiochemistry to first in man application of novel radiopharmaceuticals. CONCLUSION: Trends in radiochemistry and radiopharmacy are highlighted demonstrating the progress in the research field in various topics including new PET-labelling methods, FAPI-tracers and imaging, and radionuclide therapy being the scope of EJNMMI Radiopharmacy and Chemistry.

Clinical results of radionuclide therapy of neuroendocrine tumours with 90Y-DOTATATE and tandem 90Y/177Lu-DOTATATE: which is a better therapy option?

PURPOSE: Peptide receptor radionuclide therapy (PRRT) using radiolabelled somatostatin analogues is a treatment option for patients with disseminated neuroendocrine tumours (NET). A combination treatment using the high-energy 90Y beta emitter for larger lesions and the lower energy 177Lu for smaller lesions has been postulated in the literature.The aim of the study was to evaluate combined 90Y/177Lu-DOTATATE therapy in comparison to 90Y-DOTATATE alone. METHODS: Fifty patients with disseminated NET were included in the study prospectively and divided into two groups: group A (n=25) was treated with 90Y-DOTATATE, whereas group B (n=25) received the 1:1 90Y/177Lu-DOTATATE. The administered activity was based on 3.7 GBq/m2 body surface area in three to five cycles, with amino acid infusion for nephroprotection. RESULTS: The median overall survival time in group A was 26.2 months while in group B median survival was not reached. Overall survival was significantly higher in group B (p=0.027). Median event-free survival time in group A was 21.4 months and in group B 29.4 months (p>0.1). At the 12-month follow-up, comparison of group A vs group B showed stable disease (SD) in 13 vs 16 patients, disease regression (RD) in 5 vs 3 patients and disease progression (PD) in 3 vs 4 patients; 4 and 2 patients died, respectively. The 24-month follow-up results were SD in nine vs ten patients, RD in one patient vs none and PD in four patients in both groups; three and four patients died, respectively. Side effects were rare and mild. CONCLUSION: The results indicate that therapy with tandem radioisotopes (90Y/177Lu-DOTATATE) provides longer overall survival than with a single radioisotope (90Y-DOTATATE) and the safety of both methods is comparable.