ALPHA-PARTICLE RADIOTHERAPY WITH AT-211-LABELED MONODISPERSE POLYMER PARTICLES, AT-LABELED IGG PROTEINS, AND FREE AT-211 IN A MURINE INTRAPERITONEAL TUMOR-MODEL

Four different chemical forms of the ct-particle emitting radionuclide At-211 were injected intraperitoneally in mice inoculated intraperito neally 30 hr in advance with 10(6) cells of the K13 murine hybridoma c ell line, The different At-211 forms were (a) free At-211, (b) At-211- labeled TP-3 nonspecific monoclonal antibody (At-211-TP-3), (c) At-211 -labeled human IgG kappa (At-211-hIgG kappa), and (d) At-211-labeled m onodisperse polymer particles (At-211-MDPP), A significantly prolonged survival (P < 0.05) was observed with injected doses down to 7 kBq fo r the At-211-MDPP, and down to 25 kBq for At-211-hIgG kappa. There wer e no significant differences in survival between At-211-MDPP, At-211-h IgG kappa, and At-211-TP-3 at the dose level of 200 kBq, The group rec eiving 250 kBq free At-211 per animal had a shorter survival than the three other forms at 200 kBq, The groups treated with 500, 200, and 65 kBq At-211-MDPP had a similar survival. The group given the highest d ose of At-211-hIgG kappa (275 kBq) had the highest fraction (50%) of l ong-term survivors of all groups. Biodistribution measurements and tot al body scintigrams in mice without tumor revealed that the free At-21 1 Was distributed all over the body within 10 min after injection whil e at 2 hr a high fraction of the At-211-TP-3 and At-211-hIgG kappa was Still present intraperitoneally, In conclusion this study indicates t hat At-211-labeled MDPP and At-211-labeled IgG's may be efficient tool s for treatment of intraperitoneal superficial tumor cells and maligna nt ascites. (C) 1995 Academic Press, Inc.