Targeting Breast Cancer Using 177 Lu-Labeled Trastuzumab and Trastuzumab Fragment : First-in-Human Clinical Experience.

PURPOSE: A monoclonal antibody, trastuzumab, is used for immunotherapy for HER2-expressing breast cancers. Large-sized antibodies demonstrate hepatobiliary clearance and slower pharmacokinetics. A trastuzumab fragment (Fab; 45 kDa) has been generated for theranostic use. PATIENTS AND METHODS: Fab was generated by papain digestion. Trastuzumab and Fab have been radiolabelled with 177 Lu after being conjugated with a bifunctional chelating. The affinity and target specificity were studied in vitro. The first-in-human study was performed. RESULTS: The bifunctional chelating agent conjugation of 1-2 molecules with trastuzumab and Fab was detected at the molar ratio 1:10 in bicarbonate buffer (0.5 M, pH 8) at 37°-40°C. However, 2-3 molecules of bifunctional chelating agent were conjugated when DMSO in PBS (0.1 M, pH 7) was used as a conjugation buffer at a molar ratio of 1:10. The radiolabelling yield of DOTA-conjugated Fab and trastuzumab at pH 5, 45°C to 50°C, with incubation time 2.5-3 hours was 80% and 41.67%, respectively. However, with DOTAGA-conjugated trastuzumab and Fab, the maximum radiolabelling yield at pH 5.5, 37°C, and at 2.5-3 hours was 80.83% and 83%, respectively. The calculated K d of DOTAGA Fab and trastuzumab with HER2-positive SKBR3 cells was 6.85 ± 0.24 × 10 -8 M and 1.71 ± 0.10 × 10 -8 M, respectively. DOTAGA-Fab and trastuzumab showed better radiolabelling yield at mild reaction conditions.177 Lu-DOTAGA-Fab demonstrated higher lesion uptake and lower liver retention as compared with 177 Lu-DOTAGA-trastuzumab. However, 177 Lu-DOTAGA-Fab as compared with 177 Lu-DOTAGA-trastuzumab showed a relatively early washout (5 days) from the lesion. CONCLUSIONS: 177 Lu-DOTAGA-Fab and trastuzumab are suitable for targeting the HER2 receptors.

Synthesis, Quality Control, and Bench-to-Bed Translation of a New [68Ga]Ga-Labeled NOTA-Conjugated Bisphosphonate for Imaging Skeletal Metastases by Positron Emission Tomography.

Background: Early detection of skeletal metastasis is of great interest to determine the prognosis of cancer. Positron emission tomography-computed tomography (PET-CT) imaging provides a better temporal and spectral resolution than single photon emission computed tomography-computed tomography (SPECT-CT) imaging, and hence is more suitable to detect small metastatic lesions. Although [18F]NaF has been approved by U.S. FDA for a similar purpose, requirement of a medical cyclotron for its regular formulation restricts its extensive utilization. Efforts have been made to find suitable alternative molecules that can be labeled with 68Ga and used in PET-CT imaging. Objective: The main objective of this study is to synthesize and evaluate a new [68Ga]Ga-labeled NOTA-conjugated geminal bisphosphonate for its potential use in early detection of skeletal metastases using PET-CT. Methods: The authors performed a multistep synthesis of a new NOTA-conjugated bisphosphonic acid using thiourea linker and radiolabeled the molecule with 68Ga. The radiolabeled formulation was evaluated for its in vitro stability, affinity for hydroxyapatite (HA) particles, preclinical biodistribution in animal models, and PET-CT imaging in patients. Results: The bifunctional chelator (NOTA)-conjugated bisphosphonate was synthesized with 97.8% purity and radiolabeled with 68Ga in high yield (>98%). The radiolabeled formulation was found to retain its stability in vitro to the extent of >95% up to 4 h in physiological saline and human serum. The formulation also showed high affinity for HA particles in vitro with Kd = 907 ± 14 mL/g. Preclinical biodistribution studies in normal Wistar rats demonstrated rapid and almost exclusive skeletal accumulation of the complex. PET-CT imaging in a patient confirmed its ability to detect small metastatic skeletal lesions. Conclusions: The newly synthesized [68Ga]Ga-labeled NOTA-conjugated bisphosphonate is a promising radiotracer for PET-CT imaging for skeletal metastases.

Cancer Brachytherapy at the Nanoscale: An Emerging Paradigm.

Brachytherapy is an established treatment modality that has been globally utilized for the therapy of malignant solid tumors. However, classic therapeutic sealed sources used in brachytherapy must be surgically implanted directly into the tumor site and removed after the requisite period of treatment. In order to avoid the trauma involved in the surgical procedures and prevent undesirable radioactive distribution at the cancerous site, well-dispersed radiolabeled nanomaterials are now being explored for brachytherapy applications. This emerging field has been coined "nanoscale brachytherapy". Despite present-day advancements, an ongoing challenge is obtaining an advanced, functional nanomaterial that concurrently incorporates features of high radiolabeling yield, short labeling time, good radiolabeling stability, and long tumor retention time without leakage of radioactivity to the nontargeted organs. Further, attachment of suitable targeting ligands to the nanoplatforms would widen the nanoscale brachytherapy approach to tumors expressing various phenotypes. Molecular imaging using radiolabeled nanoplatforms enables noninvasive visualization of cellular functions and biological processes in vivo. In vivo imaging also aids in visualizing the localization and retention of the radiolabeled nanoplatforms at the tumor site for the requisite time period to render safe and effective therapy. Herein, we review the advancements over the last several years in the synthesis and use of functionalized radiolabeled nanoplatforms as a noninvasive substitute to standard brachytherapy sources. The limitations of present-day brachytherapy sealed sources are analyzed, while highlighting the advantages of using radiolabeled nanoparticles (NPs) for this purpose. The recent progress in the development of different radiolabeling methods, delivery techniques and nanoparticle internalization mechanisms are discussed. The preclinical studies performed to date are summarized with an emphasis on the current challenges toward the future translation of nanoscale brachytherapy in routine clinical practices.

Normal physiological distribution and tumor localization of 64 CuCl 2 in different human malignancies along with semiquantitative scoring: a comparative evaluation with 18 Fluorodeoxyglucose ( 18 FDG) PET-CT.

OBJECTIVE: This study aimed to explore 64-Copper-Chloride ( 64 CuCl 2 ) PET-CT in various malignancies and demonstrate a head-to-head comparison of uptake on 64 CuCl 2 PET/computed tomography (CT) and 18 fluorodeoxyglucose ( 18 FDG)-PET/CT scans for different malignancies, with an emphasis on 18 FDG nonavid malignancies. METHODS: Fifty-three patients diagnosed with various biopsy-proven malignancies (except prostate cancer) were recruited in this prospective study. All the patients underwent both 64 CuCl 2 PET/CT and 18 FDG-PET/CT. 64 CuCl 2 PET/CT was acquired at 1, 3 and 24 h time points. We studied the physiological biodistribution of 64 CuCl 2 in the various organs, corroborated the uptake of 64 CuCl 2 with various types of malignancies and comparison of their uptake with 18 FDG-PET/CT and their correlation with each other in various lesions. RESULTS: The biodistribution study showed that the liver concentrated 64 CuCl 2 the most out of all the organs, followed by the pancreas and large intestine. Liver and intestinal activity increased subsequently with delayed imaging, and the washout of 64 CuCl 2 was noted in the pancreas in delayed images and followed a hepatobiliary excretion of tracer over a period of time. In lesion-wise analysis, it was noted that the primary neuroendocrine tumor, melanoma and renal/urothelial malignancy group showed more uptake of 64 CuCl 2 , than that in metastasis and vice-versa was noted in lung and soft tissue malignancies. Comparing it with 18 FDG, it was seen that FDG showed more uptake in lesions and showed no significant correlation (Kappa value: 0.089) with the uptake of 64 CuCl 2 in the lesion-wise comparison. CONCLUSION: 64 CuCl 2 PET/CT did not show any added advantage over 18 FDG-PET/CT in the evaluation of the studied malignancies, both primary and their metastasis. Biodistribution studies showed the liver as the organ with maximum uptake, which implies it may hinder the detection of abdominal or hepatic involvement of the disease.

Brachytherapy at the nanoscale with protein functionalized and intrinsically radiolabeled [169Yb]Yb2O3 nanoseeds.

PURPOSE: Classical brachytherapy of solid malignant tumors is an invasive procedure which often results in an uneven dose distribution, while requiring surgical removal of sealed radioactive seed sources after a certain period of time. To circumvent these issues, we report the synthesis of intrinsically radiolabeled and gum Arabic glycoprotein functionalized [169Yb]Yb2O3 nanoseeds as a novel nanoscale brachytherapy agent, which could directly be administered via intratumoral injection for tumor therapy. METHODS: 169Yb (T½ = 32 days) was produced by neutron irradiation of enriched (15.2% in 168Yb) Yb2O3 target in a nuclear reactor, radiochemically converted to [169Yb]YbCl3 and used for nanoparticle (NP) synthesis. Intrinsically radiolabeled NP were synthesized by controlled hydrolysis of Yb3+ ions in gum Arabic glycoprotein medium. In vivo SPECT/CT imaging, autoradiography, and biodistribution studies were performed after intratumoral injection of radiolabeled NP in B16F10 tumor bearing C57BL/6 mice. Systematic tumor regression studies and histopathological analyses were performed to demonstrate therapeutic efficacy in the same mice model. RESULTS: The nanoformulation was a clear solution having high colloidal and radiochemical stability. Uniform distribution and retention of the radiolabeled nanoformulation in the tumor mass were observed via SPECT/CT imaging and autoradiography studies. In a tumor regression study, tumor growth was significantly arrested with different doses of radiolabeled NP compared to the control and the best treatment effect was observed with ~ 27.8 MBq dose. In histopathological analysis, loss of mitotic cells was apparent in tumor tissue of treated groups, whereas no significant damage in kidney, lungs, and liver tissue morphology was observed. CONCLUSIONS: These results hold promise for nanoscale brachytherapy to become a clinically practical treatment modality for unresectable solid cancers.

[90Y]Yttria Alumino Silicate Glass Microspheres: A Biosimilar Formulation to "TheraSphere" for Cost-Effective Treatment of Liver Cancer.

Background: Selective internal radiation therapy (SIRT) using a suitable ß--emitting radionuclide is a promising treatment modality for unresectable liver carcinoma. Yttrium-90 (90Y) [T1/2 = 64.2 h, Eß(max) = 2.28 MeV, no detectable γ-photon] is the most preferred radioisotope for SIRT owing to its favorable decay characteristics. Objective: The present study describes indigenous development and evaluation of intrinsically radiolabeled [90Y]yttria alumino silicate ([90Y]YAS) glass microsphere, a formulation biosimilar to "TheraSphere" (commercially available, U.S. FDA-approved formulation), for SIRT of unresectable liver carcinoma in human patients. Methods: YAS glass microspheres of composition 40Y2O3-20Al2O3-40SiO2 (w/w) and diameter ranging between 20 and 36 µm were synthesized with almost 100% conversion efficiency and >99% sphericity. Intrinsically labeled [90Y]YAS glass microspheres were produced by thermal neutron irradiation of cold YAS glass microspheres in a research reactor. Subsequent to in vitro evaluations and in vivo studies in healthy Wistar rats, customized doses of [90Y]YAS glass microspheres were administered in human patients. Results: [90Y]YAS glass microspheres were produced with 137.7 ± 8.6 MBq/mg YAS glass (∼6800 Bq per microsphere) specific activity and 99.94% ± 0.02% radionuclidic purity at the end of irradiation. The formulation exhibited excellent in vitro stability in human serum and showed >97% retention in the liver up to 7 d post-administration when biodistribution studies were carried out in healthy Wistar rats. Yttrium-90 positron emission tomography scans recorded at different time points post-administration of customized dose of [90Y]YAS glass microspheres in human patients showed near-quantitative retention of the formulation in the injected lobe. Conclusions: The study confirmed the suitability of indigenously prepared [90Y]YAS glass microspheres for clinical use in the treatment of unresectable hepatocellular carcinoma.

Exploratory analysis of 64 CuCl 2 PET-CT imaging in carcinoma prostate and its comparison with 68 Ga-PSMA-11 and 18 F-FDG PET-CT.

AIM: Exploratory analysis of 64 CuCl 2 PET-CT imaging in patients of carcinoma prostate and its head-to-head comparison with 68 Ga-PSMA-11 and 18 F-FDG PET-CT. METHODS: In this prospective study, 50 patients of biopsy-proven carcinoma prostate belonging to the entire spectrum of disease were evaluated, out of which 21 patients were for initial staging and 29 were for restaging/response evaluation. Both 64 CuCl 2 (early and delayed) and 68 Ga-PSMA-11 PET-CT were undertaken in all patients and 18 F-FDG PET-CT was done in patients whenever possible. All scans were done within a period of 2 weeks, without any interim therapeutic intervention. 64 CuCl 2 PET-CT was acquired at 1 and 3 h. We evaluated the physiological uptake of 64 CuCl 2 , correlated the uptake in primary with disease parameters like Gleason score and serum PSA levels, and compared the detection rates for primary and metastatic disease with 68 Ga-PSMA-11 and 18 F-FDG PET-CT. RESULTS: The detection rates of primary disease were same for both 64 CuCl 2 and 68 Ga-PSMA-11 PET-CT and both agents performed similarly in detecting extra-prostatic disease. There was no statistically significant correlation observed between the uptake of 64 CuCl 2 in the primary lesion with disease parameters. With regard to the evaluation of metastatic disease, the detection rate of 64 CuCl 2 PET-CT was 86% for lymph nodes, 77.3% for skeletal metastases and 80.6% for soft tissue metastases while 68 Ga-PSMA-11 PET-CT performed better with detection rates were 98%, 99% and 85.4%, respectively. In 17 patients where 18 F-FDG PET-CT was available, 64 CuCl 2 PET-CT detected more metastatic disease than 18 F-FDG PET-CT. CONCLUSION: 64 CuCl 2 PET-CT did not show any additional advantage over 68 Ga-PSMA-11 PET-CT in evaluation of local disease or for the assessment of metastatic disease. When compared to 68 Ga-PSMA-11 PET-CT, the absence of urinary bladder and ureteric activity allows better contrast for evaluating local disease, but it does not translate into increased disease detection.

Alpha-induced production and robust radiochemical separation of 43Sc as an emerging radiometal for formulation of PET radiopharmaceuticals.

Scandium-43 is an emerging PET radiometal that was produced by α-particle bombardment on natural CaCO3 target via natCa (α,p) 43Sc and natCa (α,n) 43Ti→43Sc reactions using K-130 cyclotron at VECC. A robust radiochemical procedure based on selective precipitation of 43Sc as Sc(OH)3 was developed for separation of the radioisotope from the irradiated target. The overall yield of the separation process was >85% and it was obtained in a form suitable for preparation of target specific radiopharmaceuticals for PET imaging of cancer.

Biochemical separation of Cetuximab-Fab from papain-digested antibody fragments and radiolabeling with 64Cu for potential use in radioimmunotheranostics.

Engineered Fab fragments of monoclonal antibodies (mAbs) after radiolabeling with suitable radiometals have the potential to play a key role in personalized radioimmunotheranostics of cancer patients. In this study, we have generated Fab fragment of Cetuximab, a mAb targeting epidermal growth factor receptor (EGFR) expression and purified from the Fc and other fragments by ultrafiltration and affinity chromatography. The Cetuximab-Fab was conjugated with a suitable bifunctional chelator and radiolabeled with no-carrier-added (NCA) 64Cu produced via 64Zn (n, p) 64Cu reaction in a nuclear reactor. The radioimmunoconjugate obtained after size exclusion chromatographic separation possessed >95% radiochemical purity and it retained its integrity over at least three half-lives of the radiometal. Biodistribution studies was performed in fibrosarcoma tumor bearing Swiss mice, which demonstrated the explicit need for purification of the Cetuximab-Fab from Fc fragments. Enhanced and rapid tumor uptake with decent tumor-to-background ratio with prolonged retention was observed when radiolabeled purified Cetuximab-Fab was intravenously administered in animal models. Overall, this preclinical study established the pivotal role of separation science and technology to obtain the radioimmunoconjugate with requisite purity in order to demonstrate optimal pharmacokinetics and maximized treatment efficacy.

A robust lyophilized kit for convenient one-step formulation of [68Ga]Ga-DOTA-E-[c(RGDfK)]2 in hospital radiopharmacy for clinical PET imaging.

The present article describes the development of robust lyophilized kit for convenient formulation of [68Ga]Ga-DOTA-E-[c(RGDfK)]2 (E = glutamic acid, R = arginine, G = glycine, D = aspartic acid, f = phenylalanine, K = lysine) radiopharmaceutical for clinical use in non-invasive monitoring of malignancies overexpressing integrin αvß3 receptors. Five batches of the kit were prepared with optimized kit contents, all of which showed high 68Ga-radiolabeling yield (>98%). Pre-clinical evaluation of the [68Ga]Ga-radiotracer in SCID mice bearing FTC133 tumour exhibited significant accumulation in the tumor xenograft. Preliminary human clinical investigation carried out in a 60 year old male patient with metastatic lung cancer revealed high radiotracer uptake in the tumor along with satisfactory target to non-target contrast. The developed kit formulation also showed a long shelf-life of at least 12 months on storage at 0 °C. All these results point towards the promising attributes of the developed kit formulation for convenient preparation of [68Ga]Ga-DOTA-E-[c(RGDfK)]2 for routine clinical use.

A solvent extraction-based procedure for removal of 46Sc impurity from reactor produced [45Ca]CaCl2 for its potential use in bone pain palliation.

Calcium-45 [T½ = 163 d, Eß (max) = 0.3 MeV] is a pure ß- emitting radioisotope which can be envisaged for potential use in palliative care of pain due to skeletal metastases of primary cancer. During production of 45Ca in nuclear reactor via 44Ca (n,γ) 45Ca route, 46Sc is co-produced as a radionuclidic impurity. In this study, we have optimized a single-step solvent extraction procedure for complete removal of 46Sc impurity from [45Ca]CaCl2. The purified radiotracer was administered intravenously in normal Wistar rats and preferential bone uptake could be demonstrated by ex vivo biodistribution studies.

Facile Synthesis of a Pt(IV) Prodrug of Cisplatin and Its Intrinsically 195mPt Labeled Analog: A Step Closer to Cancer Theranostic.

BACKGROUND AIMS AND OBJECTIVES: Cisplatin is extensively used in chemotherapy for treatment of a broad range of cancers. But its undesired side reactions with biomolecules that lead to severe side effects especially on kidney and nervous system, are limiting its clinical utility. To reduce its side effects, the kinetically inert Pt(IV) prodrug was recognized as an alternative approach from satisfactory results of preliminary experiments. But, its approval as anticancer drug for clinical use requires detailed investigations of its anticancer action and pharmacological pathways by employing its analogue which can be traced by a suitable technique. As a step closer towards translation of Pt(IV)-based prodrug from research to clinical level, a protocol for efficient synthesis of 195mPt-radiolabeled Pt(IV) prodrug was devised. MATERIALS AND METHODS: In order to achieve the aim, we started synthesis from elemental platinum avoiding lengthy steps. The synthesis protocol was standardized on its cold analogue, as [PtCl2(NH3)2(OCOCH2CH2COOH)2] which has been characterized with nuclear magnetic resonance (1H, 13C{1H} and 195Pt{1H}) spectroscopy, microanalyses and cyclic voltammetry. Also, cytotoxicity of [PtCl2(OCOCH2CH2COOH)2(NH3)2] was evaluated against MCF-7 human breast cancer cell lines using cisplatin as test control. RESULTS: Intrinsically, 195mPt-labeled analogue of prodrug was obtained with high radionuclidic and radiochemical purity. It was confirmed by chromatography and γ-ray spectrometry. CONCLUSION: The 195mPt-radiolabeled prodrug was synthesized in a facile manner. It can be utilized in evaluating the mechanism of anticancer action and pharmacokinetics by enabling synergistic use of molecular imaging and targeted drug delivery.

Production of a broad palette of positron emitting radioisotopes using a low-energy cyclotron: Towards a new success story in cancer imaging?

Over the last several years, positron emission tomography (PET) has matured as an indispensable component of cancer diagnostics. Owing to the large variability observed among the cancer patients and the need to personalize individual patient's diagnosis and treatment, the need for new positron emitting radioisotopes has continued to grow. This mini review opens with a brief introduction to the criteria for radioisotope selection for PET imaging. Subsequently, positron emitting radioisotopes are categorized as: established, emerging and futuristic, based on the stages of their advancement. The production methodologies and the radiochemical separation procedures for obtaining the important radioisotopes in a form suitable for preparation of radiopharmaceuticals for PET imaging are briefly discussed.

Efficacy and safety of 177Lu-DOTMP in palliative treatment of symptomatic skeletal metastases: a prospective study.

AIMS: Bone-seeking radiopharmaceutical 177Lu-DOTMP with favorable pharmacokinetics in the preclinical studies has been evaluated for its role in reducing bone pain and improving quality of life (QOL) in patients with symptomatic skeletal metastases. METHOD: Patients with painful widespread skeletal metastases documented on 99mTc-MDP bone scintigraphy were intravenously administered 37 MBq/kg of 177Lu-DOTMP. Visual analogue score (VAS), analgesic score, European Cooperative Group of Oncology (ECOG) and the European Organization of Research and Treatment of Cancer QLQ-C30 of all the patients were assessed at baseline and posttherapy follow-up. Adverse effects were graded according to NCI-CTCAE V 5.0. RESULTS: Twenty-seven patients with painful widespread skeletal metastases (men 18; median age 61 years; range: 18-81) were studied for their responses as complete response, partial response, minimal response, no response and pain progression based on VAS and analgesic score. Overall response was seen in 77.8% of patients (complete, partial and minimal in 29.6, 33.3 and 14.8%, respectively) with significant improvement in median VAS and mean analgesic score at 2 months posttherapy from baseline (P < 0.001). The best response was seen in patients with breast cancer (100%) followed by prostate cancer (81%) and lung cancer (28%). Improvement in QOL was noted in 40% of patients, with change in ECOG score from 3.07 ± 0.67 at baseline to 2.6 ± 0.9 at 2 months posttherapy. Grade 2/3 anemia, grade 1/2 leukopenia and grade 1/3 thrombocytopenia were seen in 37, 11.1 and 18.5% patients respectively in the follow-up. CONCLUSION: 177Lu-DOTMP appears to be efficacious treatment for bone pain palliation with improvement in QOL though less effective in patients with lung cancer. The patients had transient mild-moderate hematotoxicity.

A review of advances in the last decade on targeted cancer therapy using 177Lu: focusing on 177Lu produced by the direct neutron activation route.

Lutetium-177 [T½ = 6.76 d; Eß (max) = 0.497 MeV; maximum tissue range ~2.5 mm; 208 keV γ-ray] is one of the most important theranostic radioisotope used for the management of various oncological and non-oncological disorders. The present review chronicles the advancement in the last decade in 177Lu-radiopharmacy with a focus on 177Lu produced via direct 176Lu (n, γ) 177Lu nuclear reaction in medium flux research reactors. The specific nuances of 177Lu production by various routes are described and their pros and cons are discussed. Lutetium, is the last element in the lanthanide series. Its chemistry plays a vital role in the preparation of a wide variety of radiopharmaceuticals which demonstrate appreciable in vivo stability. Traditional bifunctional chelators (BFCs) that are used for 177Lu-labeling are discussed and the upcoming ones are highlighted. Research efforts that resulted in the growth of various 177Lu-based radiopharmaceuticals in preclinical and clinical settings are provided. This review also summarizes the results of clinical studies with potent 177Lu-based radiopharmaceuticals that have been prepared using medium specific activity 177Lu produced by direct neutron activation route in research reactors. Overall, the review amply demonstrates the practicality of the medium specific activity 177Lu towards formulation of various clinically useful radiopharmaceuticals, especially for the benefit of millions of cancer patients in developing countries with limited reactor facilities.

IAEA contribution to the development of 64Cu radiopharmaceuticals for theranostic applications.

Copper-64 is a very attractive radioisotope with unique nuclear properties that allow using it as both a diagnostic and therapeutic agent, thus providing an almost ideal example of a theranostic radionuclide. A characteristic of Cu-64 stems from the intrinsic biological nature of copper ions that play a fundamental role in a large number of cellular processes. Cu-64 is a radionuclide that reflects the natural biochemical pathways of Cu-64 ions, therefore, can be exploited for the detection and therapy of certain malignancies and metabolic diseases. Beside these applications of Cu-64 ions, this radionuclide can be also used for radiolabelling bifunctional chelators carrying a variety of pharmacophores for targeting different biological substrates. These include peptide-based substrates and immunoconjugates as well as small-molecule bioactive moieties. Fueled by the growing interest of Member States (MS) belonging to the International Atomic Energy Agency (IAEA) community, a dedicated Coordinated Research Project (CRP) was initiated in 2016, which recruited thirteen participating MS from four continents. Research activities and collaborations between the participating countries allowed for collection of an impressive series of results, particularly on the production, preclinical evaluation and, in a few cases, clinical evaluation of various 64Cu-radiopharmaceuticals that may have potential impact on future development of the field. Since this CRP was finalized at the beginning of 2020, this short review summarizes outcomes, outputs and results of this project with the purpose to propagate to other MS and to the whole scientific community, some of the most recent achievements on this novel class of theranostic 64Cu-pharmaceuticals.

Reactor produced [64Cu]CuCl2 as a PET radiopharmaceutical for cancer imaging: from radiochemistry laboratory to nuclear medicine clinic.

OBJECTIVE: Copper-64 is a useful theranostic radioisotope that is attracting renewed interest from the nuclear medicine community in the recent times. This study aims to demonstrate the utility of research reactors to produce clinical-grade 64Cu via 63Cu(n,γ)64Cu reaction and use it in the form of [64Cu]CuCl2 as a radiopharmaceutical for PET imaging of cancer in human patients. METHODS: Copper-64 was produced by irradiation of natural CuO target in a medium flux research reactor. The irradiated target was radiochemically processed and detailed quality control analyses were carried out. Sub-acute toxicity studies were carried out with different doses of Cu in Wistar rats. The biological efficacy of the radiopharmaceutical was established in preclinical setting by biodistribution studies in melanoma tumor bearing mice. After getting regulatory approvals, [64Cu]CuCl2 formulation was clinically used for PET imaging of prostate cancer and glioblastoma patients. RESULTS: Large-scale (~ 30 GBq) production of 64Cu could be achieved in a typical batch and it was adequate for formulation of clinical doses for multiple patients. The radiopharmaceutical met all the purity requirements for administration in human subjects. Studies carried out in animal model showed that the toxicity due to "cold" Cu in clinical dose of [64Cu]CuCl2 for PET scans would be negligible. Clinical PET scans showed satisfactory uptake of the radiopharmaceutical in the primary cancer and its metastatic sites. CONCLUSIONS: To the best of our knowledge, this is the first study on use of reactor produced [64Cu]CuCl2 for PET imaging of cancer in human patients. It is envisaged that this route of production of 64Cu would aid towards affordable availability of this radioisotope for widespread clinical use in countries with limited cyclotron facilities.

A simple and robust method for radiochemical separation of no-carrier-added 64Cu produced in a research reactor for radiopharmaceutical preparation.

Copper-64 is an excellent theranostic radiometal that is gaining renewed attention of the clinical community in the recent times. In order to meet the increasing demand of this radiometal, we have demonstrated the viability of its production via 64Zn (n,p) 64Cu reaction in a nuclear reactor. A semi-automated radiochemical separation module based on selective extraction of 64Cu as dithizonate complex was developed. The maximum available activity at the end of irradiation was ~ 700 MBq. The overall yield of 64Cu after the separation process was >85% and it could be obtained with ~12 GBq/µg specific activity, >99.9% radionuclidic purity and >98% radiochemical purity. The separated 64Cu could be utilized for preparation of a wide variety of radiopharmaceuticals.