Abstract
Early diagnosis of bone metastases is crucial to prevent skeletal-related events, and for that, the non-invasive techniques to diagnose bone metastases that make use of image-guided radiopharmaceuticals are being employed as an alternative to traditional biopsies. Hence, in the present work, we tested the efficacy of a gallium-68 (68Ga)-based compound as a radiopharmaceutical agent towards the bone imaging in positron emitting tomography (PET). For that, we prepared, thoroughly characterized, and radiolabeled [68Ga]Ga-NODAGA-pamidronic acid radiopharmaceutical, a 68Ga precursor for PET bone cancer imaging applications. The preparation of NODAGA-pamidronic acid was performed via the N-Hydroxysuccinimide (NHS) ester strategy and was characterized using liquid chromatography-mass spectrometry (LC-MS) and tandem mass spectrometry (MSn). The unreacted NODAGA chelator was separated using the ion-suppression reverse phase-high performance liquid chromatography (RP-HPLC) method, and the freeze-dried NODAGA-pamidronic acid was radiolabeled with 68Ga. The radiolabeling condition was found to be most optimum at a pH ranging from 4 to 4.5 and a temperature of above 60 °C. From previous work, we found that the pamidronic acid itself has a good bone binding affinity. Moreover, from the analysis of the results, the ionic structure of radiolabeled [68Ga]Ga-NODAGA-pamidronic acid has the ability to improve the blood clearance and may exert good renal excretion, enhance the bone-to-background ratio, and consequently the final image quality. This was reflected by both the in vitro bone binding assay and in vivo animal biodistribution presented in this research.
Highlights
Cancer is one of the leading causes of mortality worldwide
We found that the NODAGA‐pamidronic acid (NODPAM) precursor was successfully prepared via the NHS ester conjugation strategy
The liquid chromatography-mass spectrometry (LC-mass spectrometry (MS)) and reverse phase-high performance liquid chromatography (RP-HPLC) chromatogram showed a similar pattern in addition to the MSn results, which confirmed the NODPAM’s structure
Summary
Cancer is one of the leading causes of mortality worldwide. The efforts in implementing an accurate diagnosis, in cancer staging, are necessary for optimal patient management.Molecules 2020, 25, 2668; doi:10.3390/molecules25112668 www.mdpi.com/journal/moleculesMolecules 2020, 25, x FOR PEER REVIEWApproximately 18.1 million new cancer cases were reported in 2018 [1], and it is foreseen to rise just by growth and ageing of the population. Cancer is one of the leading causes of mortality worldwide. The efforts in implementing an accurate diagnosis, in cancer staging, are necessary for optimal patient management. 18.1 million new cancer cases were reported in 2018 [1], and it is foreseen to rise just by growth and ageing of the population. In Malaysia, bone cancer is the third most prevalent cancer in males, with an group of cancer. 2018 [1], of and it is cancer foreseenistoessential rise just to by prevent any ageing skeletal‐related events, and for that, the use of cost‐effective single‐photon growth and of the population. In Malaysia, bone cancer is the third most prevalent emission cancer in
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