Abstract
Anaplastic lymphoma kinase (ALK), an oncogenic receptor tyrosine kinase, has emerged as a therapeutic target in solid and hematologic tumors. Although several ALK inhibitors have gained recent approval for therapy, non-invasive indicators of target engagement or for use as predictive biomarkers in vivo are lacking. Therefore, we designed and synthesized a radiolabeled analogue of the ALK inhibitor ceritinib, [(18)F]fluoroethyl-ceritinib ([(18)F]-FEC), for use with positron emission tomography. We used two methods to synthesize [(18)F]-FEC. First, [(18)F]fluoroethyl-tosylate was prepared, coupled with ceritinib, and the product purified to yield [(18)F]-FEC. Alternatively, a precursor compound was synthesized, directly fluorinated with (18)F-fluoride, and purified to yield [(18)F]-FEC. The first method produced [(18)F]-FEC with an average decay-corrected yield of 24% (n = 4), specific activity of 1200 mCi/µmol, and >99% purity; synthesis time was 115 min from the end of bombardment. The second method produced [(18)F]-FEC with an average yield of 7% (n = 4), specific activity of 1500 mCi/µmol, and >99% purity; synthesis time was 65 min from the end of bombardment. The synthesis of a novel (18)F-labeled analogue of ceritinib has been achieved in acceptable yields, at high purity, and with high specific activity. The compound is a potential positron emission tomography imaging agent for the detection of ALK-overexpressing solid tumors such as lung cancer.