[Influence on extratumoral organ activities of tumor-affinity samarium-153 preparations].

Possibilities to exercise an influence on the biodistribution of a tumor-affine 153Sm-preparation, samarium-153-nitrilotriacetate (NTA), were tested. Animals experiments on tumor-bearing mice after additional application of EDTMP (ethylenediamine tetramethylene phosphonate) for the reduction of extratumorale liver-radioactivity and yttrium chloride for the reduction of unwanted underground radioactivity in bone were carried out. Furthermore, the combination of both measurements was tested. The biodistribution of 153Sm-NTA showed a rather low tumor-radioactivity of app. 0.72%/g. The additional EDTMP-application caused a dose-dependent decrease of the underground-radioactivity in liver especially if given 2 h in advance or simultaneously. The additional application of the stable yttrium salt reduced the bone radioactivity on simultaneous increase of liver- and spleen-radioactivity and practically unchanged tumor-radioactivity. The combined use of EDTMP together with the bone-affine metal salt led to a reduction of liver radioactivity on simultaneous reduction of bone radioactivity. The background radioactivity can be reduced on unchanged tumor-radioactivity by combined Na-EDTMP/YCl3-application. The present results do not allow a therapeutic exploitation because of the low tumor accumulation.