TREATMENT OF INTRACRANIAL HUMAN GLIOBLASTOMA BY DIRECT INTRATUMORAL ADMINISTRATION OF I-131-LABELED ANTI-TENASCIN MONOCLONAL-ANTIBODY BC-2

Ten patients with bulky brain glioblastoma, recurring after surgery, radiotherapy or chemotherapy, underwent direct intralesional radioimmunotherapy (RIT) using a monoclonal antibody (MAb), BC-2, raised against tenascin and labelled with I-131. Tenascin, the BC-2-recognized glycoprotein, is an antigen expressed by the stroma of malignant gliomas but not by normal cerebral tissue. Preliminary studies in animals have demonstrated the ability of anti-tenascin radiolabelled MAbs to detect and reduce tumours. A mean MAb dose of 1.93 mg (corresponding to 55 1.3 MBq of I-131) Was injected directly into the tumour by means of a stereotaxic technique. Both systemic and local toxicity were negligible. After 24 hr, average tumour BC-2 uptake was 4.9% per gram and its effective half-life in neoplastic tissue was 66.5 hr: a mean radiation dose to target tissue of 36.48 cGy per MBq of injected I-131 was delivered. Normal brain tissue and the major organs were spared. Most patients underwent multiple injections, reaching a cumulative tumour radiation ranging from 7,000 to 41,000 cGy. RIT failed to achieve any result in 4 of the 10 patients; in 3, the disease was stabilized; in the remaining 3, CT scan or NMR revealed 2 partial remission ( > 50% reduction in tumour volume; PR) and I complete remission (CR). One patient with PR relapsed after II months; the other 2 patients were still maintaining their responses at the time of writing, 17 (CR) and 12 (PR) months after injection.