Fractionated radiolabeled antiferritin therapy for patients with recurrentHodgkin's disease

The objective of this study was to determine the therapeutic ratio of fract ionated radiolabeled immunoglobulin therapy (RIT) for patients with recurre nt Hodgkin's disease. Ninety patients with recurrent Hodgkin's disease rece ived 2 mg of yttrium-90-labeled polyclonal rabbit antihuman ferritin IgG i. v. Fifty-seven patients received a single (unfractionated) administration p er treatment cycle; 11 of them were treated with 0.3 mCi/kg body weight, 39 were treated with 0.4 mCi/kg body weight, and 7 received 0.5 mCi/kg body w eight per treatment cycle. Thirty-three patients had their radiolabeled imm unoglobulin administration separated (fractionated) in 2 x 0.25 mCi/kg body weight (total activity, 0.5 mCi/kg), The interval between fractions was 1 week. Radioimmunoconjugates did not cause serious acute side effects. In vi vo radioimmunoconjugates were stable. Human antirabbit IgG antibodies were found in 2 of 50 retreated patients (<5%). Hematological toxicity was the o nly side effect noted in all patients, and it was usually temporary. Respon se rates (RRs) were 20%, 61%, and 86% after 0.3, 0.4, or 0.5 mCi/kg unfract ionated yttrium-90-labeled antiferritin. The RR for patients treated with f ractionated RIT was 42%. In the fractionated RIT group, complete responses were decreased, and progressive disease increased (P < 0.05). Complete resp onses had a medium duration of 6 months. Median survival times were 390 day s for 1 x 0.4 mCi/kg and 300 days for the 2 x 0.25 mCi/kg patient group. Fr actionation did not provide the expected decrease in hematological toxicity or the expected increase in tumor RRs.