Radioimmunotherapy of @entity1 XXXX by 131I-labelled monoclonal anti- @entity787 antibodies in a nude @entity19 model.

@entity1 @entity137 @entity19 @entity5 @entity787 @entity694
A mixture of 3 MAbs directed against 3 different @entity787 epitopes was radiolabelled with 131I and used for the treatment of a @entity1 @entity694 transplanted s.c. into @entity19 . Intact MAbs and F(ab')2 fragments were mixed because it had been shown by autoradiography that these 2 antibody forms can penetrate into different areas of the @entity5 nodule. Ten days after transplantation of @entity694 T380 a single dose of 600 microCi of 131I MAbs was injected i.v. The @entity5 grafts were well established (as evidenced by exponential growth in untreated @entity19 ) and their size continued to increase up to 6 days after radiolabelled antibody injection. @entity5 shrinking was then observed lasting for 4-12 weeks. In a control group injected with 600 microCi of 131I coupled to irrelevant monoclonal IgG, @entity5 growth was delayed, but no regression was observed. @entity5 of @entity19 injected with the corresponding amount of unlabelled antibodies grew like those of untreated @entity19 . Based on measurements of the effective whole-body half-life of injected 131I, the mean radiation dose received by the animals was calculated to be 382 rads for the antibody group and 478 rads for the normal IgG controls. The genetically immunodeficient animals exhibited no increase in mortality, and only limited bone-marrow @entity137 was observed. Direct measurement of radioactivity in @entity19 dissected 1, 3 and 7 days after 131I-MAb injection showed that 25, 7.2 and 2.2% of injected dose were recovered per gram of @entity5 , the mean radiation dose delivered to the @entity5 being thus more than 5,000 rads. These experiments show that therapeutic doses of radioactivity can be selectively directed to @entity1 @entity694 by i.v. injection of 131I-labelled anti- @entity787 MAbs.
