An investigation of the efficacy of astatine-211--tellurium colloid for the treatment of experimental malignant ascites in mice reveals that this alpha-emitting radiocolloid can be curative without causing undue toxicity to normal tissue. By comparison, negatron-emitting phosphorus-32 as colloidal chromic phosphate had no antineoplastic activity. The most compelling explanation for this striking difference is the dense ionization and short range of action associated with alpha-emission. These results have important implications for the development and use of alpha-emitters as radiocolloid therapy for the treatment of human tumors.

Department of R a d i o t h e r a p y , Mount S i n a i School o f Medicine, One Gustave L. Levy P l a c e , N e w Y o r k , NY 1.0029 'Department of Chemistry , Brookhaven N a t i o n a l L a b o r a t o r y , Upton, NY 11973 SUMMARY The a l p h a e m i t t i n g r a d i o h a l o g e n 211At h a s p o t e n t i a l u s e a s a r a d i o t h e r a p e u t i c a g e n t when l i n k e d t o b i o l o g i c a l l y a c t i v e molecules. The r a n g e of compounds which may be a s t a t i n a t e d is l i m i t e d by r e l a t i v e l a c k o f knowledge of o r g a n o a s t a t i n e s y n t h e s e s . The n r o d u c t i o n of a s t a t o v i n y l s t e r o i d s was c a r r i e d o u t v i a e l e c t r o p h i l i c s u b s t i t u t i o n of t r i -n -b u t y l s t a n n y l v i n y l s t e r o i d s w i t h a s t a t i d e i n t h e p r e s e n c e of mild o x i d i z i n g a g e n t s . The a s t a t i n a t e d s t e r o i d 8 are s y n t h e s i z e d r a p i d l y and i n c a r r i e r -f r e e f a s h i o n y i e l d i n g compounds of h i g h r a d i o c h e m i c a l p u r i t y . Key words: 211At, 17-alptfp-211At-vinylastradiol , 1 3 -beta-methoxy-l7-alpha-' A t -v i n y l e s t r a d i o l , d e s t a n n y l a t i o n . t o whom c o r r e s p o n d e n c e to be a d d r e s s e d 0362-4803/87x)91117-06$05.~