5-[I-125]IODO-2'-DEOXYURIDINE IN THE RADIOTHERAPY OF SOLID CNS TUMORSIN RATS

We have been investigating the therapeutic efficacy of the thymidine a nalog 5-iodo-2'-deoxyuridine (IUdR) when radiolabeled with the Auger e lectron emitter I-125 in rats bearing intrathecal (i.t.) or intracereb ral (i.c.) 9L gliosarcoma solid tumors, [I-125]IUdR was infused i.t. ( via subarachnoid catheters) or intracerebrally over a 5- or 2-day peri od; equimolar concentrations of [I-125]IUdR were infused into control animals. Hind-leg paralysis and/or survival were followed over time, T he results indicate that compared with [I-127]IUdR, rats bearing intra thecal tumors and infused i.t. with [I-125]IUdR showed significant pro longation of the onset of median paralysis (15.2 versus 9 days). Simil arly, the median survival of rats bearing intracerebral tumors and inf used i.c. with [I-125]IUdR was significantly increased (24 versus 17 d ays), The data substantiate the antineoplastic potential of [I-125]IUd R and indicate a promising role for this radiopharmaceutical in the tr eatment of CNS cancers.