Survival of patients with resistant Hodgkin's disease after polyclonal yttrium 90-labeled antiferritin treatment

A follow-up study was initiated of patients with Hodgkin's disease who were treated with yttrium 90-labeled antiferritin. Prescription method, pharmacokinetics, acute and late side effects, and survival were evaluated.

Patients had measurable disease and failed > or = two multiagent chemotherapy regimens previously (N = 44). All patients received 5-mCi indium 111-labeled antiferritin 2 mg intravenously and were scanned repeatedly by gamma camera. In five patients, polyclonal antiferritin (rabbit, pig, or baboon) failed to target the tumor. Thirty-nine patients were injected intravenously with 10-, 20-, 30-, 40-, or 50-mCi yttrium 90-labeled antiferritin 2 to 5 mg. Patients received between one and five cycles. Some patients were supported with 5 x 10(7) autologous bone marrow cells per kilogram.

Yttrium 90-labeled polyclonal antiferritin does not produce immunologic, pharmacologic, or microbiologic complications in vivo. Bone marrow toxicity is the only side effect observed. Overall response rate is 20 of 39, or 51%. Two patients had stable disease. A significant positive correlation is found between blood radioactivity level 1 hour after radioimmunoconjugate administration and subsequent response of Hodgkin's disease. A dosage in millicuries per kilogram provides a higher positive correlation with blood radioactivity levels 1 hour after administration than a dosage in millicuries per square meter of body-surface area or in total millicuries. Fifty percent of patients survive for > or = 6 months.

The low-dose protein used (2 to 5 mg) indicates that the high response rate is due to radiation and not to immunologic effects of the antibody. High-activity administrations followed by bone marrow transplantation are not required for tumor response. The therapeutic ratio of radiolabeled antiferritin is higher than the therapeutic ratio observed in most phase I studies of chemotherapeutic agents. This analysis does not identify a superior mode of treatment for patients with end-stage Hodgkin's disease. However, in a heavily pretreated patient population, prolonged survival is observed after relatively inexpensive treatment. Preclinical research with yttrium 90-labeled antiferritin indicates that significant increases in tumor dose can be obtained in the future without an increase in normal tissue toxicity.