28.02.2013 Views

autologous blood and marrow transplantation - Blog Science ...

autologous blood and marrow transplantation - Blog Science ...

autologous blood and marrow transplantation - Blog Science ...

SHOW MORE
SHOW LESS

Create successful ePaper yourself

Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.

Radioimmunotherapy of Common Epithelial Tumors<br />

R.HJ. Begent<br />

Department of Oncology, Cancer Research Campaign Targeting <strong>and</strong> Imaging<br />

Group, Royal Free <strong>and</strong> University College Medical School, London, U.K.<br />

Common epithelial tumors are prone to develop resistance to cytotoxic drugs<br />

<strong>and</strong> have heterogeneous distribution of tumor associated antigens <strong>and</strong> an inhomogeneous<br />

vascular supply. Radioimmunotherapy is an attractive approach to their<br />

treatment because resistance can be overcome if a sufficient dose of radiation can<br />

be delivered selectively <strong>and</strong> the range of targeted beta-emitting radionuclides can<br />

place non-antigen-producing tumor cells within range of lethal damage. Separate<br />

therapeutic strategies are required to treat poorly vascularized tumor areas. A<br />

mathematical model based on clinical data indicates that efficiency of antibody<br />

targeting depends most on antibody specificity, affinity, avidity, stability within the<br />

tumor, antigen density, <strong>and</strong> flow through <strong>and</strong> clearance from the <strong>blood</strong> <strong>and</strong><br />

extravascular tumor spaces. Design of antibody molecules, choice of radionuclide,<br />

<strong>and</strong> radiobiological considerations can be manipulated to optimize therapy. This<br />

will be illustrated in the context of colorectal carcinoma using engineered<br />

antibodies to carcinoembryonic antigen of different valency <strong>and</strong> stability <strong>and</strong><br />

labeled with 13<br />

'iodine or 90<br />

yttrium. The need for <strong>and</strong> the effects of combining<br />

radioimmunotherapy with antivascular therapy using dimethyl xanthenone acetic<br />

acid will also be shown. The tools are now available to permit improved radioimmunotherapy<br />

of common epithelial tumors, although the problem remains more<br />

challenging than the therapy of lymphoid malignancies.<br />

692

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!