Synthesis of [18F]benzamide ([18F]INER-1577) as Histone Deacetylase (HDACs) Imaging Agent

2664 Objectives HDACs expression levels in humans have been correlated with many diseases, including several forms of cancer, heart failure, inflammatory diseases, and neurodegenative diseases1.2. Several HDACs inhibitors have been developed as therapeutic and imaging agents for the above-mentioned diseases3.4. We report herein the synthesis of [18F]Fluoroethyl-INER1577 as a Histone Deacetylases (HDACs) imaging agent. Methods [18F]Fluoroethyl-INER1577 was synthesized through a two-step method. Briefly, fluorination of TsOCH2CH2OTs (1) with K[18F]/K2.2.2 in ACN at 90oC for 10min followed by purification with Waters Sep-Pak Accell Plus QMA Plus Short Cartridge gave TsOCH2CH218F (2). Reaction of INER1577(3) with TsOCH2CH218F in DMSO at 100 oC for 30 min followed by purification with HPLC(C-18 column, 5μm, 250 × 4.6mm, mobile phase:30% H2O/70% methanol, flow rate:1mL/min) gave [18F]Fluoroethyl-INER1577 (Scheme 1). The inhibitions of Fluoroethyl-INER1577 on tumor cells growth were carried out with breast cancer cell line 4T1 and MCF-55. The whole-body and brain distributions of [18F]Fluoroethyl-INER1577 in rats were determined using micro-PET scanner and the data was analyzed using PMOD. Results The radiochemical yield of TsOCH2CH218F was ~70% (EOS) in a synthesis time of 15 min from EOB. Both chemical and radiochemical purities were >90%. The radiochemical yield of [18F]Fluoroethyl-INER1577 was ~ 5-10% (EOS) in a synthesis time of 60 min. Both chemical and radiochemical purities were >99%.In vitro cell inhibition studies showed that Fluoroethyl-INER1577 has inhibitory activity against these four cell lines, especially for 069MCF-5 (~70%, Table 1). MicroPET/CT studies in rats showed that [18F]Fluoroethyl-INER1577 could penetrate BBB (Fig.1 and Fig.2). Conclusions [18F]Fluoroethyl-INER1577 has been synthesized in~ 5-10% yield (EOS) in a synthesis time of 60 min from EOB. In vitro studies showed that Fluoroethyl-INER1577 inhibited breast cancer cell line 4T1 and MCF-5 growth. Micro-PET/CT studies in rats show that [18F]Fluoroethyl-INER1577 may be a HDACs imaging agent. The synthesis of other INER-1577 analogs as HDACs therapeutic and/or imaging agents continue. References:(1). Guaff, J et al. An epigenetic blockade of cognitive functions in the neurodegenerating brain. Nature 2012,483(7388),222-226.(2). Guan,J. S et al.,HDAC2 negatively regulates memory formation and synaptic plasticity. Nature 2009, 459, 55-60.(3). Strebl, M.G et al. Development of a Fluorinated Class‑I HDAC Radiotracer Reveals Key Chemical Determinants of Brain Penetrance. ACS chemical neuroscience 2015, A-F.(4). Wagner, F. F et al. Kinetically Selective Inhibitors of Histone Deacetylase 2 (HDAC2) as Cognition Enhancers. Chemical science 2015, 6 (1), 804-815.(5) Lee, S. J et al., Sonic hedgehog-induced histone deacetylase activation is required for cerebellar granule precursor hyperplasia in medullobalstoma.PLoS One 2013, 9;8(8). $$graphic_1261009B-1219-4D72-9734-0145250A098A$$ $$graphic_16564005-5BDE-4FB6-9269-5D4E5668025C$$ $$graphic_3666741B-D342-4A0F-ABEA-A888264ED48B$$ $$graphic_E9B667F5-F9E4-4938-AED4-D6B8AF911A10$$ $$table_{B2EFB3FB-639D-47F4-A7CA-328A6C7E0A9B}$$$$graphic_{82CE88FE-31E3-4A4D-A8A3-0E065F1F5BDE}$$$$graphic_{8512492F-21B9-4C29-81F3-9DD275B325FE}$$$$graphic_{03592593-825C-486C-8C82-5F24A9CE0CF5}$$