Poly(ethylene glycol)-Conjugated Anti-EGF Receptor Antibody C225 with Radiometal Chelator Attached to the Termini of Polymer Chains
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- 作者：Xiaoxia Wen ; Qing-Ping Wu ; Yang Lu ; Zhen Fan ; Chusilp Charnsangavej ; Sidney Wallace ; Diana Chow ; and Chun Li
- 刊名：Bioconjugate Chemistry
- 出版年：2001
- 出版时间：July 2001
- 年：2001
- 卷：12
- 期：4
- 页码：545 - 553
- 全文大小：99K
- 年卷期：v.12,no.4(July 2001)
- ISSN：1520-4812
文摘
Several biological barriers, including significant liver uptake, limit the clinical application ofradiolabeled antibodies in radioimmunoscintigraphy. Here, a general approach is described forradiolabeling of monoclonal antibodies conjugated with poly(ethylene glycol) (PEG). This strategy isdemonstrated with C225, a monoclonal antibody directed against epidermal growth factor (EGF)receptor. We synthesized a heterofunctional PEG with one end attached to a radiometal chelator,diethylenetriaminepentaacetic acid (DTPA), and the other end to a protected thiol group, S-acetylthioacetate. After a deprotection step, the resulting DTPA-PEG-SH was conjugated to maleimide-activated C225 to yield DTPA-PEG-C225 conjugate. Characterization of DTPA-PEG-C225 withimmunoprecipitation and Western blot analysis revealed that the conjugate was biologically active inbinding to the EGF receptor in A431 cells. Competitive EGF receptor binding assay in MDA-MB-468cells showed that DTPA-PEG-C225, with up to 60% of the amino groups in C225 substituted, retained66% of C225's binding affinity. Moreover, DTPA-PEG-C225 with increasing degrees of NH2 substitutionfrom 20% to 70% retained the activity of C225 to induce apoptosis in DiFi cells. More importantly,DTPA-PEG-C225 demonstrated less nonspecific interaction than DTPA-C225. Pharmacokineticanalysis using 111In-labeled compounds revealed narrower steady-state distribution of 111In-DTPA-PEG-C225 than 111In-DTPA-C225, probably due to reduced nonspecific binding of PEG-modifiedantibody to tissues. The terminal half-life (t1/2,
) of 111In-DTPA-PEG-C225, 21.1 h, was shorter thanthat of 111In-DTPA-C225, 52.9 h. These data suggest that 111In-DTPA-PEG-C225 may provide betterimaging characteristics than 111In-DTPA-C225, and that using PEG as a linker between the monoclonalantibody and DTPA may be a promising strategy in optimizing the imaging characteristics ofimmunoscintigraphic agents.
) of 111In-DTPA-PEG-C225, 21.1 h, was shorter thanthat of 111In-DTPA-C225, 52.9 h. These data suggest that 111In-DTPA-PEG-C225 may provide betterimaging characteristics than 111In-DTPA-C225, and that using PEG as a linker between the monoclonalantibody and DTPA may be a promising strategy in optimizing the imaging characteristics ofimmunoscintigraphic agents.