The Potential of Radiolabeled Bisphosphonates in SPECT and PET for Bone Imaging.

Skeletal-related events due to bone metastases can be prevented by early diagnosis using radiological or nuclear imaging techniques. Nuclear medicine techniques such as Single Photon Emission Computed Tomography (SPECT) and Positron Emission Tomography (PET) have been used for diagnostic imaging of bone for decades. Although it is widely recognized that conventional diagnostic imaging techniques such as Computed Tomography (CT) and Magnetic Resonance Imaging (MRI) have high sensitivity, low cost and wide availability, the specificity of both techniques is rather low compared to nuclear medicine techniques. Nuclear medicine techniques, on the other hand, have improved specificity when introduced as a hybrid imaging modality, as they can combine physiological and anatomical information. Two main radiopharmaceuticals are used in nuclear medicine: [99mTc]-methyl diphosphonate ([99mTc]Tc-MDP) from the generator and [18F]sodium fluoride ([18F]NaF) from the cyclotron. The former is used in SPECT imaging, while the latter is used in PET imaging. However, recent studies show that the role of radiolabeled bisphosphonates with gallium-68 (68Ga) and fluorine-18 (18F) may have a potential role in the future. This review, therefore, presents and discusses the brief method for producing current and future potential radiopharmaceuticals for bone metastases.

Preparation, Optimisation, and In Vitro Evaluation of [18F]AlF-NOTA-Pamidronic Acid for Bone Imaging PET.

[18F]sodium fluoride ([18F]NaF) is recognised to be superior to [99mTc]-methyl diphosphate ([99mTc]Tc-MDP) and 2-deoxy-2-[18F]fluoro-D-glucose ([18F]FDG) in bone imaging. However, there is concern that [18F]NaF uptake is not cancer-specific, leading to a higher number of false-positive interpretations. Therefore, in this work, [18F]AlF-NOTA-pamidronic acid was prepared, optimised, and tested for its in vitro uptake. NOTA-pamidronic acid was prepared by an N-Hydroxysuccinimide (NHS) ester strategy and validated by liquid chromatography-mass spectrometry analysis (LC-MS/MS). Radiolabeling of [18F]AlF-NOTA-pamidronic acid was optimised, and it was ensured that all quality control analysis requirements for the radiopharmaceuticals were met prior to the in vitro cell uptake studies. NOTA-pamidronic acid was successfully prepared and radiolabeled with 18F. The radiolabel was prepared in a 1:1 molar ratio of aluminium chloride (AlCl3) to NOTA-pamidronic acid and heated at 100 °C for 15 min in the presence of 50% ethanol (v/v), which proved to be optimal. The preliminary in vitro results of the binding of the hydroxyapatite showed that [18F]AlF-NOTA-pamidronic acid was as sensitive as [18F]sodium fluoride ([18F]NaF). Normal human osteoblast cell lines (hFOB 1.19) and human osteosarcoma cell lines (Saos-2) were used for the in vitro cellular uptake studies. It was found that [18F]NaF was higher in both cell lines, but [18F]AlF-NOTA-pamidronic acid showed promising cellular uptake in Saos-2. The preliminary results suggest that further preclinical studies of [18F]AlF-NOTA-pamidronic acid are needed before it is transferred to clinical research.

Cyclotron Production of Gallium-68 Radiopharmaceuticals Using the 68Zn(p,n)68Ga Reaction and Their Regulatory Aspects.

Designing and implementing various radionuclide production methods guarantees a sustainable supply, which is important for medical use. The use of medical cyclotrons for radiometal production can increase the availability of gallium-68 (68Ga) radiopharmaceuticals. Although generators have greatly influenced the demand for 68Ga radiopharmaceuticals, the use of medical cyclotrons is currently being explored. The resulting 68Ga production is several times higher than obtained from a generator. Moreover, the use of solid targets yields end of purification and end of synthesis (EOS) of up to 194 GBq and 72 GBq, respectively. Furthermore, experiments employing liquid targets have provided promising results, with an EOS of 3 GBq for [68Ga]Ga-PSMA-11. However, some processes can be further optimized, specifically purification, to achieve high 68Ga recovery and apparent molar activity. In the future, 68Ga will probably remain one of the most in-demand radionuclides; however, careful consideration is needed regarding how to reduce the production costs. Thus, this review aimed to discuss the production of 68Ga radiopharmaceuticals using Advanced Cyclotron Systems, Inc. (ACSI, Richmond, BC, Canada) Richmond, Canada and GE Healthcare, Wisconsin, USA cyclotrons, its related factors, and regulatory concerns.

In vitro cytotoxicity of Auger electron-emitting [67Ga]Ga-trastuzumab.

INTRODUCTION: Molecular radiotherapy exploiting short-range Auger electron-emitting radionuclides has potential for targeted cancer treatment and, in particular, is an attractive option for managing micrometastatic disease. Here, an approach using chelator-trastuzumab conjugates to target radioactivity to breast cancer cells was evaluated as a proof-of-concept to assess the suitability of 67Ga as a therapeutic radionuclide. METHODS: THP-trastuzumab and DOTA-trastuzumab were synthesised and radiolabelled with Auger electron-emitters 67Ga and 111In, respectively. Radiopharmaceuticals were tested for HER2-specific binding and internalisation, and their effects on viability (dye exclusion) and clonogenicity of HER2-positive HCC1954 and HER2-negative MDA-MB-231 cell lines was measured. Labelled cell populations were studied by microautoradiography. RESULTS: Labelling efficiencies for [67Ga]Ga-THP-trastuzumab and [111In]In-DOTA-trastuzumab were 90% and 98%, respectively, giving specific activities 0.52 ± 0.16 and 0.61 ± 0.11 MBq/µg (78-92 GBq/µmol). At 4 nM total antibody concentration and 200 × 103 cells/mL, [67Ga]Ga-THP-trastuzumab showed higher percentage of cell association (10.7 ± 1.3%) than [111In]In-DOTA-trastuzumab (6.2 ± 1.6%; p = 0.01). The proportion of bound activity that was internalised did not differ significantly for the two tracers (62.1 ± 1.4% and 60.8 ± 15.5%, respectively). At 100 nM, percentage cell binding of both radiopharmaceuticals was greatly reduced compared to 4 nM and did not differ significantly between the two (1.2 ± 1.0% [67Ga]Ga-THP-trastuzumab and 0.8 ± 0.9% for [111In]In-DOTA-trastuzumab). Viability and clonogenicity of HER2-positive cells decreased when each radionuclide was incorporated into cells by conjugation with trastuzumab, but not when the same level of radioactivity was confined to the medium by omitting the antibody conjugation, suggesting that 67Ga needs to be cell-bound or internalised for a therapeutic effect. Microautoradiography showed that radioactivity bound to individual cells varied considerably within the population. CONCLUSIONS: [67Ga]Ga-THP-trastuzumab reduced cell viability and clonogenicity only when cell-bound, suggesting 67Ga holds promise as a therapeutic radionuclide as part of a targeted radiopharmaceutical. The causes and consequences of non-homogeneous uptake among the cell population should be explored.

Cost-Effectiveness of Adjuvant Trastuzumab Therapy for Early Breast Cancer in Asia: A Systematic Review.

OBJECTIVES: To systematically review and assess the quality of the economic evidence of adjuvant trastuzumab usage in early breast cancer in Asian countries. METHODS: Literature search was performed using 6 electronic databases (PubMed, Scopus, Ovid MEDLINE, EconLit, National Health Service Economic Evaluation Database, and ISI Web of Knowledge). The final search was performed in October 2018. All potential economic studies were then checked for eligibility. The reporting and methodological qualities of each study were independently assessed by 2 authors of this review, using the Consolidated Health Economic Evaluation Reporting Standards, Drummond, and Philips checklists. To compare the different currencies used in these studies, all costs were converted into US dollars (2016). RESULTS: A total of 6 studies were included; most of them were performed from the healthcare provider perspective. The incremental cost-effectiveness ratio for evaluation performed for a lifetime horizon were reported at $8573 and $20 816 per quality-adjusted life-year in 2 studies. The model outcome was generally sensitive to the changes in trastuzumab drug acquisition cost and discount rate, as well as its clinical effectiveness. For the quality assessment, all studies fulfilled more than 50% of the requirements in the Consolidated Health Economic Evaluation Reporting Standards, Drummond, and Philips checklists. CONCLUSIONS: Adjuvant trastuzumab therapy is considered a cost-effective option for early breast cancer in Asian countries including China, Iran, Japan, Singapore, and Taiwan. All studies were generally well conducted. Economic evaluations from the societal perspective, with inclusion of indirect and informal care costs, are warranted to facilitate informed decision making among policy makers.

Knowledge on Alzheimer's Disease among Public Hospitals and Health Clinics Pharmacists in the State of Selangor, Malaysia.

The prevalence of Alzheimer's disease (AD) has increased with the fast growing of aging population, thereby posing great challenges to provision of care for AD patients. Pharmacists play a vital role in the management of AD; this includes recognizing early symptoms of AD, providing medication counseling to AD patients and their caretakers, and identifying potential adverse drug reactions. A comprehensive understanding of the disease progression, as well as the pharmacological therapy, is essential to provide effective care to AD patients. The level of knowledge about AD among the pharmacists, however, remains unknown. Hence, this study aimed to assess the knowledge on AD among the pharmacists in public hospitals and health clinics and its correlates. A clear picture of the characteristics associated with different levels of knowledge could facilitate the targeted re-training of pharmacists. The 30-item validated Alzheimer disease knowledge scale (ADKS) tool was pilot-tested and used in this cross-sectional study. All pharmacists, from nine public hospitals and seven public health clinics in the State of Selangor, Malaysia, were invited to participate in this cross-sectional survey. The ADKS score was computed and compared across demographics characteristics. A total of 445 pharmacists responded to the survey. These pharmacists had a moderate overall score in ADKS; nevertheless, high scores were recorded in the domains of treatment management and care giving. No difference in AD knowledge was found among pharmacists worked in public hospitals and health clinics, except for the domain of care giving (p = 0.033). Ethnicity and age group were independent predictors of ADKS score in the current study. The pharmacists in the current study had moderate AD knowledge. On-going education and training programme on AD, in particular the domains other than treatment management and care giving, should be provided to the pharmacists to ensure delivery of quality care to AD patients.