DOTA-ZOL: A Promising Tool in Diagnosis and Palliative Therapy of Bone Metastasis-Challenges and Critical Points in Implementation into Clinical Routine

• Published in: Molecules (Basel, Switzerland) Switzerland), 2020-06, Vol.25 (13), p.2988
• Main Authors: Meisenheimer, Michael, Kürpig, Stefan, Essler, Markus, Eppard, Elisabeth
• Format: Article
• Language: English
• Subjects: Bisphosphonates; Bone Density Conservation Agents - chemistry; Bone Density Conservation Agents - pharmacology; bone metastasis; Bone Neoplasms - diagnostic imaging; Bone Neoplasms - drug therapy; Bone Neoplasms - secondary; Bronchial Neoplasms - diagnostic imaging; Bronchial Neoplasms - drug therapy; Bronchial Neoplasms - pathology; Calcification; Carbon; Chromatography; Critical point; Diagnosis; Disease; Gallium Radioisotopes; gallium-68; Heterocyclic Compounds, 1-Ring - chemistry; High performance liquid chromatography; Humans; Hydroxyapatite; Isotope Labeling; Liquid chromatography; Metabolism; Metastases; Metastasis; Methods; module system; Nuclear medicine; Palliation; Palliative Care; Patients; Purification; Quality Control; radiolabelling synthesis; Radiopharmaceuticals - chemistry; Reactors; Thin layer chromatography; Zoledronic acid; Zoledronic Acid - chemistry; Zoledronic Acid - pharmacology
• ISSN: 1420-3049; 1420-3049
• DOI: 10.3390/molecules25132988

The novel compound 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-ZOL (DOTA-conjugated zoledronic acid) is a promising candidate for the diagnosis and therapy of bone metastasis. The combination of the published methodology for this bisphosphonate with pharmaceutical and regulatory requirements turned out to be unexpectedly challenging. The scope of this work is the presentation and discussion of problems encountered during this process. Briefly, the radiolabelling process and purification, as well as the quality control published, did not meet the expectations. The constant effort setting up an automated radiolabelling procedure resulted in (a) an enhanced manual method using coated glass reactors, (b) a combination of three different reliable radio thin-layer chromatography (TLC) methods instead of the published and (c) a preliminary radio high-pressure liquid chromatography (HPLC) method for identification of the compound. Additionally, an automated radiolabelling process was developed, but it requires further improvement, e.g., in terms of a reactor vessel or purification of the crude product. The published purification method was found to be unsuitable for clinical routine, and an intense screening did not lead to a satisfactory result; here, more research is necessary. To sum up, implementation of DOTA-ZOL was possible but revealed a lot of critical points, of which not all could be resolved completely yet.