ENHANCED RADIOIMMUNOTARGETING OF I-125 LABELED L6-BIOTIN MONOCLONAL-ANTIBODY (MAB) BY COMBINING PRELOAD OF COLD L6 MAB AND SUBSEQUENT IMMUNOADSORPTION IN RATS
M. Garkavij et al., ENHANCED RADIOIMMUNOTARGETING OF I-125 LABELED L6-BIOTIN MONOCLONAL-ANTIBODY (MAB) BY COMBINING PRELOAD OF COLD L6 MAB AND SUBSEQUENT IMMUNOADSORPTION IN RATS, Cancer research, 55(23), 1995, pp. 5874-5880
The present study investigates whether tumor:normal tissue uptake rati
os of radiolabeled monoclonal antibodies can be further improved by a
combination of extracorporeal immunoadsorption (ECIA) and preload with
unlabeled idiotypic monoclonal antibody. Athymic rats, heterotranspla
nted with human lung carcinoma under the kidney capsule (SR tumor) and
i.m. (IM tumor), were divided into four study groups: controls, ECIA,
preload, and combined preload+ECIA. The preload+ECIA procedure reduce
d the whole-body and plasma activity by 48 and 89%, respectively. Afte
r such combined procedure, the uptake of I-125-labeled L6-biotin in SR
tumors was unchanged, while the uptake in normal tissues was consider
ably reduced, Tumor (T):bone marrow ratio was then increased by 17.5 t
imes (after ECIA) and by 4.5 times (24 h after ECIA). Similar enhancem
ents were achieved for T:liver and T:kidney ratios, For the IM tumors,
the ratios were not as high as for SR tumors, The effects on T:normal
ratios of preload+ECIA in combination were synergistic, The combined
procedure resulted both in an increased uptake and prolonged persisten
ce of I-125-labeled L6-biotin in the SR tumors and also in a reduction
of corresponding uptake values in organs critical for radiation.