INTRATUMORAL ADMINISTRATION OF 5-[I-123]IODO-2' DEOXYURIDINE IN A PATIENT WITH A BRAIN-TUMOR

We have initiated a study in which patients suspected of having primar y gliomas are given a single intracerebral injection of the thymidine analog 5-[I-123]iodo-2'-deoxyuridine ([I-123]IUdR). The purpose of the study is to determine the biodistribution of the radiopharmaceutical and to calculate dose estimates to the tumor and normal tissues. Metho ds: A patient with a cystic glioma was injected with [I-123]IUdR. Whol e-body scans and brain scans were obtained at various times after inje ction, and blood, urine and stools were collected and assayed for radi oactivity to assess its biodistribution and clearance. Results: Scinti graphic imaging demonstrated that the distribution of radiolabeled IUd R was mainly confined to the tumor (injection site), stomach and bladd er. Disappearance from the tumor site and blood clearance were delayed probably due to collection in the cystic lesion. Eighty percent of th e injected dose was recovered in the urine. Conclusion: The pharmacoki netics of [I-123]IUdR locoregionally administered to a human glioma in situ resembled those observed in a rat glioma model where administrat ion of the radiopharmaceutical radiolabeled with the Auger electron em itter I-125 was therapeutically effective.