A COMPARISON OF CU-67-LABELED AND I-131-LABELED FORMS OF MONOCLONAL-ANTIBODIES SEN7 AND SWA20 DIRECTED AGAINST SMALL-CELL LUNG-CANCER

The intact anti-SCLC monoclonal antibody (MAb) SEN7 and its F(ab')(2) were labelled with the beta-emitting isotope Cu-67. Both materials ret ained their biological activity in vitro as determined by the Lindmo a ssay. In a direct comparison of in vivo distribution in a xenograph mo del I-131- and Cu-67-labelled intact SEN7 showed similar absolute tumo ur accumulation. Blood levels were markedly lower in the case of the C u-67-labelled antibody, resulting in improved tumour:blood ratios whic h reached a maximum of 13:1 compared with only 4.5:1 for I-131-SEN7. I n the case of the 67Cu-labelled F(ab')(2), very high accumulation of t he nuclide was observed in the kidney. Levels of radio copper in liver and spleen were also found to be significantly raised when compared w ith radio iodine. SWA20, a MAb which had previously failed to show any selective in vivo accumulation in tumour xenografts when labelled wit h radio iodine showed higher and more stable tumour accumulation when labelled with Cu-67. (C) 1994 Wiley-Liss, Inc.