TY - JOUR T1 - cGMP production of [<sup>18</sup>F]3F4AP for human PET imaging JF - Journal of Nuclear Medicine JO - J Nucl Med SP - 1461 LP - 1461 VL - 62 IS - supplement 1 AU - Karla Ramos-Torres AU - Jacqueline Noel AU - Danielle Vesper AU - Peter Rice AU - Pedro Brugarolas AU - Daniel Yokell Y1 - 2021/05/01 UR - http://jnm.snmjournals.org/content/62/supplement_1/1461.abstract N2 - 1461Objectives: [18F]3-fluoro-4-aminopyridine ([18F]3F4AP) is a PET radioligand for imaging demyelinated lesions in the brain based on the multiple sclerosis (MS) drug 4-aminopyridine (4AP)1,2. [18F]3F4AP binds to voltage-gated K+ channels present in demyelinated axons and has been used for PET imaging in rodent models of MS as well as non-human primates1,3. Current radiosynthesis for [18F]3F4AP is performed in a GE Tracerlab Fx2N autosynthesizer following published methods4. The goals of this work were to adapt the synthesis to a cassette-based synthesizer (the Neptis Perform automated synthesis device produced by Ora) and validate the synthesis in a cGMP laboratory for human use. Methods: Production and formulation of [18F]3F4AP was adapted to be executed on the Neptis Perform Synthesizer. Briefly, [18F]fluoride produced by bombardment of [18O]water was transferred to the Neptis Perform synthesis box and passed through an anion exchange cartridge. [18F]Fluoride was trapped on the cartridge and then eluted into the reactor vessel using a mixture of K2CO3 and Kryptofix[2.2.2]. To the azeotropically dried mixture [18F]KF/K222 was added methyl 3-nitroisonicotinate (1) for nucleophilic fluorination at 80 ºC for 15 min followed by basic hydrolysis of intermediate 2 with NaOH at 100ºC for 10 min. Reaction mixture was then acidified with HCl, followed by triethylamine addition and evaporation to dryness under heat, N2 flow and vacuum. Curtius-Yamada rearrangement was performed on 2 with addition of DPPA in DMSO and heating at 130 ºC for 10 min (Figure 1). Reaction was then quenched with 0.5% NH4OH followed by semi-preparative RP-HPLC purification on a XBridge C-18, 5µm, 250x10 mm column, 5:95 EtOH:20mM sodium phosphate (pH 8), 4 mL/min. Eluted product (Rt = 11 min) was diluted with 0.9 % sodium chloride for injection and assessed for quality control testing by appearance, radionuclidic identity and purity, radiochemical identity and purity, chemical purity, determination of mass of 3F4AP and other chemical impurities, total radioactivity assay, pH determination, Kryptofix limit test, residual solvent determination, sterilizing membrane filter integrity test, and bacterial endotoxin test. Results: An automated method to produce [18F]3F4AP was adapted for the Neptis Perform automated synthesis device. Three productions of [18F]3F4AP were carried out to validate this radiotracer for human use. The resulting [18F]3F4AP solution is clear, colorless, and neutral pH with a typical non-decay corrected radiochemical yield of 1-3% after 90 min total synthesis from end of bombardment. All batches met FDA/USP quality control requirements for PET radiopharmaceuticals. Conclusions: [18F]3F4AP was validated for human use with a Neptis Perform radiosynthesis module. The developed methodology facilitates the radiosynthesis of this radiotracer with an additional cassette-based system, therefore providing an alternative method for production at ours and other centers. This method affords [18F]3F4AP in high radiochemical purity (98 ± 2 %, n = 3) and high molar activity (4568 ± 616 mCi/µmol, n = 3) at end of synthesis. To our knowledge, this is the first report of a cGMP synthesis of [18F]3F4AP which has been accepted by FDA in an IND. Acknowledgements: We thank Tim Beaudoin, Steven Gallo, David F. Lee Jr., Jessica Lee, Tiffany L’Heureux, Brian McAvoy, Ramesh Neelamegam and Hamid Sabet, of the Massachusetts General Hospital for radionuclide production, synthesis, and technical support. References: 1Brugarolas, P. et al. Sci Rep 8, 607, doi:10.1038/s41598-017-18747-3 (2018). 2Brugarolas, P., Reich, D. S. &amp; Popko, B. Mol Imaging 17, 1536012118785471, doi:10.1177/1536012118785471 (2018). 3Guehl, N. J. et al. J Cereb Blood Flow Metab, 271678X20963404, doi:10.1177/0271678X20963404 (2020). 4Basuli, F., Zhang, X., Brugarolas, P., Reich, D. S. &amp; Swenson, R. E. J Labelled Comp Radiopharm, doi:10.1002/jlcr.3560 (2017). ER -