FACTORS INFLUENCING HEMATOLOGIC TOXICITY OF RADIOIMMUNOTHERAPY WITH I-131-LABELED ANTICARCINOEMBRYONIC ANTIGEN ANTIBODIES

BACKGROUND. Several investigators have reported a considerable variabi lity in the observed hematologic toxicity after radioimmunotherapy (RA IT) with monoclonal antibodies (MoAb) given at similar amounts of radi oactivity based on body surface area and/or similar radiation absorbed doses given to the red marrow. The authors investigated various facto rs potentially affecting hematologic toxicity after RAIT with I-131-la beled anti-carcinoembryonic antigen (CEA) MoAb to identify the statist ically significant factors from those commonly perceived clinically to substantially contribute to this toxicity. METHODS, Ninety-nine patie nts who received I-131-labeled anti-CEA MoAb for the treatment of CEA- producing cancers were assessed for platelet and white blood cell toxi city based on the common Radiation Therapy Oncology Group criteria. Mu ltivariate regression analysis was used to identify the statistically significant factors affecting toxicity among the following variables: red marrow dose, baseline platelet and white blood cell counts, bone a nd/or marrow metastases, prior chemotherapy or radiotherapy, timing of prior chemotherapy or radiotherapy in relationship to RAIT, type and number of prior chemotherapeutic regimens, age, sex, antibody form, an d cancer type. RESULTS AND CONCLUSIONS, Red marrow dose, baseline plat elet or white blood cell counts, multiple bone and/or marrow metastase s, and chemotherapy 3-6 months before RAIT were the only four signific ant factors affecting hematologic toxicity according to multivariate a nalysis. The identification of bone and/or mar row metastases and rece nt chemotherapy as significant factors for hematologic toxicity could be important in the design of future clinical trials. (C) 1997 America n Cancer Society.