TY - JOUR T1 - A mass spectrometry-based method for the determination of <em>in vivo</em> biodistribution of tumor targeting small molecule-metal conjugates JF - bioRxiv DO - 10.1101/2022.03.04.483029 SP - 2022.03.04.483029 AU - Ettore Gilardoni AU - Aureliano Zana AU - Andrea Galbiati AU - Theo Sturm AU - Jacopo Millul AU - Samuele Cazzamalli AU - Dario Neri AU - Riccardo Stucchi Y1 - 2022/01/01 UR - http://biorxiv.org/content/early/2022/03/07/2022.03.04.483029.abstract N2 - Nuclear medicine plays a key role in modern diagnosis and cancer therapy. The development of tumor targeting radionuclide conjugates (also named Small Molecule-Radio Conjugates - SMRCs) represents a significant improvement over the clinical use of metabolic radiotracers (e.g., [18F]-Fluorodeoxyglucose) for imaging and over the application of biocidal external beam radiations for therapy. During the discovery of SMRCs, molecular candidates must be carefully evaluated typically by performing biodistribution assays in preclinical tumor models. Quantification methodologies based on radioactive counts are typically demanding due to safety concerns, availability of radioactive material, and infrastructures. In this article, we report the development of a mass spectrometry (MS)-based method for the detection and quantification of small molecule-metal conjugates (SMMCs) as cold surrogates of SMRCs. We applied this methodology for the evaluation of the biodistribution of a particular class of tumor-targeting drug candidates based on natLu, natGa, natF and directed against Fibroblast Activation Protein (FAP). The reliability of the LC-MS analysis was validated by direct comparison of MSbased and radioactivity-based biodistribution data. Results show that MS biodistribution of stable isotope metal conjugates is an orthogonal tool for the preclinical characterization of different classes of radiopharmaceuticals.Competing Interest StatementD.N. is a cofounder and shareholder of Philogen S.p.A. (http://www.philogen.com/en/), a Swiss-Italian Biotech company that operates in the field of ligand-based pharmacodelivery. E.G., A.Z, A.G., T.S., J.M, S.C, and R.S. are employees of Philochem AG, the daughter company of Philogen, that owns and has patented OncoFAP, BiOncoFAP and their derivatives. No other potential conflicts of interest relevant to this article exist.ACNAcetonitrileDOTAGA2-(4,7,10-tris(carboxymethyl)-1,4,7,10-tetraazacyclododecan-1-yl)pentanedioic acidEDTAEthylenediaminetetraacetic acidFAFormic acidFAPFibroblast activation proteinHPLCHigh pressure liquid chromatographyHRMSHigh resolution mass spectrometryICP-MSInductively coupled plasma mass spectrometryID/gInjected dose per gramISInternal standardLCLiquid chromatographyLC-MSLiquid chromatography – Mass spectrometryMSMass spectrometryNODAGA2-(4,7-bis(carboxymethyl)-1,4,7-triazonan-1-yl)pentanedioic acidNOTA2,2’-(7-carboxy-1,4,7-triazonane-1,4-diyl)diacetic acidPBSPhosphate-buffered salineSIMSingle ion monitoringSMMCSmall molecule metal conjugateSMRCSmall molecule radio conjugateSPESolid phase extractionTFATrifluoroacetic acid ER -