XWH - 06 - 1 - 0475 TITLE : Breast Tumor Detection and Treatment Using Tarvacin Labeled with Arsenic Radionuclides

Radioarsenic labeled radiopharmaceuticals cou ld add sp ecial features to molecular im agingwith positron emission tomography (PET). For example the long phy sical half-lives ofAs(T1/2 = 26 h) and As (T1/2 = 17.8 d) in conjunction with their high positron branching rates of88 % a nd 29 % respecti vely, all ow the investigation of slow p hysiological or metabolicalprocesses, l ike the enr ichment and biodistribution of monoclonal an tibodies (mab) in tumortissue or the characterization of stem cell trafficking. A method for separation and purificationof no carrier add ed (nca) arsenic from irradiated metallic ge rmanium ta rgets based ondistillation and anion exchange is developed. It finally converts th e arsenic into an *As(III)synthon in PBS buffer and pH 7 suitable for labeling of proteins via A s-S bond formations.The method deliv ers radioarsenic in high purity w ith separ ation factors of 1 0 fr omgermanium and an ov erall y ield fro m target to la beling sy nthon of > 4 0%. In a pro of-of-principle experiment, th e monoclonal antibody Be vacizumab, d irected against th e hu manVEGF recep tor w as l abeled wi th a rad iochemical pur ity > 90% within 1 h at roo mtemperature with ncaAs.