Radioimmunoscintigraphy and radioimmunotherapy with RCC MABS

The basis for immunoscintigraphy and immunotherapy depends upon selective specificity of antibody. The authors have developed multiple (A6H, C5H, D5D) reactive InGl monoclonal antibodies (MAB) utilizing surgical tissue homogenates and renal cell carcinoma (RCC) cell lines. Selective specificity was demonstrated by cell binding ELISA and in vitro immunohistochemistry. MABS were labeled with I-13l (s.a. 10 ..mu..Ci/..mu..g) and RCC xenografts were imaged in 160 nude mice. Specificity index (SI) (tissue/blood cpm/g) was calculated for normal tissue, control xenograft and RCC xengograft and ranged 5-25 for RCC and <1 for normal tissue. RCC xenografts imaged at 5, 24 48 hours without background subtraction demonstrated tumors as small as 40 mg. Tl evaluate effectiveness of radifoimmunotherapy, mice bearing RCC xenografts received: no treatment, non-radiolabeled A6H, I-131-labeled control IgGl MAB (I-131-AFP22) 100 ..mu..Ci), I-131-labeled A6H (100 ..mu..Ci). Mice receiving no treatment, non-labeled A6H or labeled control MAB exhibited rapid progression of disease, while mice treated with I-131-labeled A6H exhibited 50% reduction in tumor size at 60 days. Histologic examination of tissue revealed fibrosis and significant reduction of tumor cells. Dosimetry indicated labeled A6H resulted in total body dose of 300 rads and RCC xenograft of 5,500 rads. The authors conclude that preselected RCC MABSmore » localize in target tissue sufficient for imaging without background subtraction or extensive computer processing. In addition, effective radioimmunotherapy can be demonstrated in RCC xenografts with significant arrest of growth and reduction in tumor size.« less