A preliminary study of brain gliomas with H17E2 monoclonal antibody: immunoscintigraphy and pharmacokinetics

Ten patients with relapsing high grade brain gliomas and one patient with low grade glioma were studied with a monoclonal antibody (H17E2) against placental alkaline phosphatase. In addition 2 patients with relapsing high grade glioma were studied with a non specific antibody (4D513/2118). 1 mCi of Iodine-131-labelled H17E2 was administered intracarotidly (i.c.) in two, and intravenously (i.v.) in 9 patients. Immunoscintigrams were taken at 0, 2, 24, 48 and 72 hours. Radioactivity was monitored in blood and urine. Tumour/non-tumour ratios were estimated (max. 2.45). All high grade gliomas receiving specific antibody irrespective of the route of administration, gave a positive immunoscintigraphic pattern, increasing in intensity with time. Disappearance of radioactivity in blood was biexpontential with a long component over 30 hours. Urinary excretion of radioactivity ranged from 3.7-21.7% of administered dose/day. The patient with low grade glioma and the patients receiving non specific monoclonal antibody showed a negative pattern, a fast blood clearance and a high urinary excretion. We conclude that a) Iodine-131 labelled H17E2 proved to be stable in vivo and produced satisfactory tumour localisation and b) i.v. route was as good as i.c.