BODY AND BLOOD CLEARANCE AND MARROW RADIATION-DOSE OF I-131 LYM-1 IN PATIENTS WITH B-CELL MALIGNANCIES

Fifty-eight per cent of patients with B-cell malignancies had durable responses to treatment with I-131-Lym-1. Myelosuppression manifested b y peripheral blood cytopenia was the radiation dose-limiting toxicity. The mean biologic half-times were 3.3 and 31.2 h for the fast and slo w phases, respectively, of the blood clearance and 33.5 h for the clea rance from the total body. Nonpenetrating radiation from the blood con tributed 0.18 rad and penetrating radiations from the total body contr ibuted 0.18 rad per administered mCi to the bone marrow. The average t otal contribution from both of these sources was 0.36 +/- 0.14 rad mCi -1. Clearances and marrow radiation doses were remarkably constant amo ng different patients and among different therapy doses for the same p atient. These results are potentially useful as an initial approximati on for other mouse monoclonal antibodies of the same isotype. While ra diation to normal marrow from 'spill-over' incident to specific target ing of I-131-Lym-1 on malignant B-cells in the marrow is not addressed in this publication because it is unique for each patient, it should be considered in the case of individual patients.