Brand Caroline, Fröhlich Max, Ring Janine, Schliemann Christoph, Kessler Torsten, Mantke Verena, König Simone, Lücke Martin, Mesters Rolf M, Berdel Wolfgang E, Schwöppe Christian
Department of Medicine A, Hematology, Oncology and Pneumology, ‡Integrated Functional Genomics (IZKF Muenster), and §Central Institute for Animal Experimentation, University of Muenster , Albert-Schweitzer-Campus 1, D-48129 Muenster, Germany.
Mol Pharm. 2015 Oct 5;12(10):3749-58. doi: 10.1021/acs.molpharmaceut.5b00508. Epub 2015 Aug 31.
tTF-NGR retargets the extracellular domain of tissue factor via a C-terminal peptide GNGRAHA, a ligand of the surface protein aminopeptidase N (CD13) and upon deamidation of integrin αvβ3, to tumor vasculature. tTF-NGR induces tumor vascular infarction with consecutive antitumor activity against xenografts and selectively inhibits tumor blood flow in cancer patients. Since random PEGylation resulted in favorable pharmacodynamics of tTF-NGR, we performed site-directed PEGylation of PEG units to the N-terminus of tTF-NGR to further improve the antitumor profile of the molecule. Mono-PEGylation to the N-terminus did not change the procoagulatory activity of the tTF-NGR molecule as measured by Factor X activation. Experiments to characterize pharmacokinetics in mice showed a more than 1 log step higher mean area under the curve of PEG20k-tTF-NGR over tTF-NGR. Acute (24 h) tolerability upon intravenous application for the mono-PEGylated versus non-PEGylated tTF-NGR compounds was comparable. PEG20k-tTF-NGR showed clear antitumor efficacy in vivo against human tumor xenografts when systemically applied. However, site-directed mono-PEGylation to the N-terminus does not unequivocally improve the therapeutic profile of tTF-NGR.
tTF-NGR通过C端肽GNGRAHA（表面蛋白氨肽酶N（CD13）的配体）将组织因子的细胞外结构域重新靶向，并在整合素αvβ3脱酰胺后，靶向肿瘤血管。tTF-NGR诱导肿瘤血管梗死，对异种移植瘤具有连续的抗肿瘤活性，并选择性地抑制癌症患者的肿瘤血流。由于随机聚乙二醇化导致tTF-NGR具有良好的药效学性质，我们对tTF-NGR的N端进行了聚乙二醇单元的定点聚乙二醇化，以进一步改善该分子的抗肿瘤特性。通过因子X激活测定，N端的单聚乙二醇化并未改变tTF-NGR分子的促凝血活性。在小鼠体内进行的药代动力学表征实验表明，PEG20k-tTF-NGR的曲线下平均面积比tTF-NGR高1个对数以上。单聚乙二醇化和未聚乙二醇化的tTF-NGR化合物静脉注射后的急性（24小时）耐受性相当。当全身应用时，PEG20k-tTF-NGR在体内对人肿瘤异种移植瘤显示出明显的抗肿瘤疗效。然而，N端的定点单聚乙二醇化并不能明确改善tTF-NGR的治疗特性。
