211At labeling of a monoclonal antibody and its Fab fragment: Cytotoxicity on human gastric cancer cells and biodistribution in nude mice with tumor xenografts

An antigastric cancer monoclonal antibody, 3H11 and its Fab fragment, were labeled with #-emitter ²¹¹At using p-[²¹¹At] astatobenzoic acid (PAtBA) intermediate. The astatinated antibodies had conspicuous cytotoxic effect on human gastric cancer cell M85 in vitro. Tissue distribution of the astatinated antibodies were investigated in nude mice with subcutaneous tumor xenografts by i.v. injection. The astatinated Fab fragment was better suitable for 7.2-hour half life of ²¹¹At, since its tumor uptake remained higher (9.48–8.42 I.D%/g) than the astatinated intact antibody (~4.0 I.D%/g) from 3 to 14-hour post injection. However, the undesired high ²¹¹At uptake of the astatinated antibodies in some normal tissues, such as stomach, kidney and lung, suggested that the ²¹¹At labeled antibodies should be further explored.