Quantitative whole-body autoradiography of radiolabeled antibody distribution in a xenografted human cancer model (original) (raw)
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International Journal of Cancer, 1989
The magnitude and kinetics of tumor uptake of a monoclonal antibody (MAb) directed against carcinoembryonic antigen (CEA) in the GW-39 human colorectal cancer xenograft differ according to the animal used (nude mouse or hamster) and the site of implantation of the tumor within the animal (cheek pouch, leg muscle, subcutaneous or liver). Several physiological factors have been evaluated in an attempt to explain these differences in radio-antibody accumulation. The following observations have been made: (I) The animal host with the slower blood clearance of radio-antibody and the higher non-tumor tissue uptake has the higher tumor uptake;
Cancer Immunology Immunotherapy, 1991
The inaccessibility of radiolabeled antibody to poorly vascularized regions of solid tumors may reduce the therapeutic efficacy of these macromolecules. Theoretical mathematical models have predicted that increasing the protein dose administered would reduce the heterogeneity of radioantibody distribution. This investigation was undertaken to evaluate this hypothesis in experimental animal models. We have utilized the technique of macroautoradiography to demonstrate an increase in tumor penetration of the lower-affinity 125I-labeled NP-4 or higher-affinity Immu-14 anti-carcinoembryonic antigen (anti-CEA) mAbs into small (60.25-0.4 g) and large (0.8-1.5 g) GW-39 and LS174T human colonic xenografts, grown subcutaneously in the nude mouse, when 400 gg unlabeled antibody is administered simultaneously with 10 gg (100 gCi) radioantibody. Further increases in protein to 800 gg result in a reduction in total tumor uptake of the antibody. These differences in mAb distribution could be visualized as early as 1 day after antibody injection. Improved mAb penetration was also achieved for the Mu-9 anti-CSAp (anti-mucin) antibody using 800 gg unlabeled antibody. An irrelevant antibody (AFP-7-31) was found to be homogeneously distributed 3 days after injection, even at a low protein dose. Attempts to improve mAb penetration by increasing the protein dose in the GS-2 colorectal tumor, a model that has low NP-4 accretion as a result physiological barriers separating antibody from antigen, were not snccessful. These results suggest that a more homogeneous distribution of radioantibody can be achieved by carefully selecting a dose of unlabeled antibody to coadminister. Work is currently in progress to determine the effect of improved tumor distribution of radioantibody on the therapeutic potential of a single dose of radioantibody. * This work has been supported in part by USPHS grants CA-37895, CA 39841, and RR-05 903 (Division
Cancer Immunology Immunotherapy, 1992
The biodistributions of three 13q-labeled murine monoclonal antibodies, NP-4 and Immu-14 anti-(carcinoembryonic antigen), and Mu-9 anti-(colon-specific antigen p), were determined at antibody protein doses varying from 1 gg to 1000 gg in nude mice with small (0.1-0.4 g) GW-39 human colonic cancer xenografts. For each antibody, the percentage of the injected dose per gram of tumor and tumor/nontumor ratios were constant over a wide protein dose range. However, at high protein doses (above 100 gg for NP-4 and Immu-14) the percentage of the injected dose per gram of tumor and tumor/nontumor ratios decreased. Assuming that the uptake of a control anti-(c~-fetoprotein) antibody represents the amount of antibody that accumulates in the tumor nonspecifically (i. e., antigen-independently), it could be shown that for each antibody the amount of antibody protein that accumulates in the tumor specifically, increases linearly with the protein dose, reaching a plateau level at the highest doses tested. The growth inhibition of GW-39 tumor transplants in nude mice treated with 131I-labeled antibody at either low or high antibody protein dose was compared. These experiments indicated that, in this experimental model, enhanced antibody protein dose may decrease the therapeutic efficacy of radioiodinated antibodies. It is suggested that heterogeneous distribution at low protein dose, with intense localization around the blood vessels, may enhance the tumoricidal effect of radioantibodies.
Radioimmunodetection of human tumor xenografts by monoclonal antibodies
Cancer Research
Mouse lgG2a monoclonal antibodies with specific binding reac tivity in vitro to human tumors of the gastrointestinal tract were radioiodinated and injected into immunosuppressed mice xenografted with human colon carcinoma tumors. The antibodies preferentially localized in tumor tissue compared to normal mouse tissue, as determined by differential tissue counting of radioactivity. Preferential antibody localization in tumor tissue was greatly enhanced when Ffab'fe fragments of the antibodies were used, and the fragments localized specifically only in those tumors that bind the antibodies in vitro and not in unrelated tumors. Radiolabeled fragments of an anti-hepatitis virus mono clonal antibody of the same isotype as the specific antibody did not localize in tumors. Tumors could be located by whole-body -y-scintigraphy with radiolabeled specific antibody F(ab')2 frag ments without background subtraction.
Cancer, 1984
To determine if in vivo binding specificities of monoclonal antibodies to tumor nodules would reflect in vitro antibody specificities as determined by radioimmunoassay, two monoclonal antibodies were selected for imaging of human tumor xenografts in nude mice. By in vitro radioimmunoassay, antibody 436 binds to the M2O melanoma cell line, but not to the P3 carcinoma cell line; antibody 44 binds to P3 but not to MZO. Both antibodies are I @ , isotypes. Nude mice bearing an M20 melanoma in one flank and a P3 carcinoma in the other were injected idtravenously with 5 to 25 pg of each antibody labeled with either 1-125 or 1-131; in separate animals the labels were reversed. Animals were imaged daily with a scintillation camera equipped with a pinhole collimator. On day 6 the animals were sacrificed, and binding of the antibodies to the tumors and normal tissue were compared. Antibody 436 had up to a twofold binding advantage in vivo for the melanoma, whereas antibody 44 had up to a twofold binding advantage for the carcinoma, thus confirming the in vitro specificities of each. However, imaging on day 4 and computer analysis of percent radioactivity in the tumors showed that tumor images were related directly to tumor size and relatively uninfluenced by antibody specificity. Thus, even though antibody specificity can be demonstrated by differential tissue counting, imaging of tumor deposits appears to involve a nonspecific phenomenon that is largely dependent upon tumor weight.
Cancer research, 1990
The pharmacokinetics and tissue distribution of the monoclonal antibody radioconjugate 111In-diethylenetriaminepentaacetic acid-KC-4G3, which is directed against a high molecular weight mucin(s) antigen expressed on the human milk fat globule and many epithelial cell membranes, were examined in BALB/c nude mice with and without xenografts of the human tumor lines ZR-75 (mammary adenocarcinoma, KC-4G3 antigen positive) and BALL-1 (B-cell lymphoma, KC-4G3 antigen negative). Plasma of ZR-75 and BALL-1 tumor-bearing nude mice inoculated with 111In-KC-4G3 had a higher initial volume of distribution (V1), steady state volume of distribution (Vss), and plasma clearance and a lower initial half-life (t1/2 alpha) than non-tumor-bearing nude mice. There were no significant differences in biological half-life (t1/2 beta) in tumor- and non-tumor-bearing nude mice. Urinary and fecal excretion of radioactivity by ZR-75 tumor-bearing mice was greater than that of BALL-1 and non-tumor-bearing mice....
European Journal of Cancer and Clinical Oncology, 1987
antibody (MAb) B72.3 has been linked successfully to several radio-n&ides forming stable complexes and analyzed in vitro and in vivo without significant loss of its immunoreactivi&. Previous studies have demonstrated that radioiodinated B72.3 can selectively bind to human colorectal carcinomas grown in athymic mice. The same successful localization has been obtained more recently in clinical trials in patients with me&static colorectal carcinomas. The high degree of selective binding of this MAb has led us to investigate its potential as a radioimmutwtherapeutic agent. Athymic mice bearing human colon car&toma xenografts were injected with either 300 or 500 @i of '3'I-B72.3 IgG to assess the effect of the radiolabeled MAb on the tumor growth as well as potential toxic side effects in vital organs. In mice treated with the '3'I-B72.3 IgG, a marked inhibition of the growth of the human colon carcinoma xenograft was noticed in comparison with control mice injected with PBS or control mice that received unlabeled B72.3 IgG. Th tumors from these control mice weighed 2.7 to 3.7 times more than the tumors from the treated mice at 17 days post-inoculation of the radiolabeled MAb. Autoradiographic studies demonstrated a heterogeneous distribution of radioactivity throughout the tumor mass at 11 days post-administration of MAb. With time, the periphery of the tumor contained significantb less radioactivity than the medial areas composed of predominantly nonviable tissue; these&dings suggest that the more biologically active peripheral tumor zones, with higher mitotic rates, could have partially escaped the radiation effect of the single dose administered. The tumor cells could have continued dividing when the levels of circulating radiolabeled monoclonal antibody had decreased.
Acta Oncologica, 1991
The biokinetics of seven '3'I-labelled monoclonal antibodies (MAbs), directed against human colon carcinoma and one lzsIlabelled unspecific MAb have been examined. The study in nude mice, carrying human colon carcinoma, was intended to be a step in the selection of the most suitable antibody for clinical scintigraphy. The biological half-life in blood was found to be between 1.3 and 7.4 days for the different MAbs. Chromatography of plasma samples showed that the radioiodine was mainly bound to IgGsized molecules. The (normal tissue)/blood ratios were similar for all the MAbs. The tumour/blood ratio was 0.41 for the unspecific MAb and 0.49-1.1 for the specific MAbs, and the tumour/muscle ratio was between 3.2 and 6.8 for the specific MAbs 6 days after injection. For one MAb tumour/blood and tumour/muscle ratios were 3.9 and 9.8 respectively 9 days after injection. Localization indices were at their highest 2.6 6 days after injection. For at least two of the monoclonal antibodies the tumour/blood and turnour/ muscle ratios found are high enough to justify clinical trials regarding their usefulness for scintigraphy of colon cancer in man.
2013
The therapeutic effect of radioimmunotherapy depends on the distribution of the absorbed dose in relation to viable cancer cells within the tumor, which in turn is a function of the activity distribution. The aim of this study was to investigate the distribution of 177 Lu-DOTA-BR96 monoclonal antibodies targeting the Lewis Y antigen over 7 d using a syngeneic rat model of colon carcinoma. Methods: Thirty-eight tumor-bearing rats were intravenously given 25 or 50 MBq of 177 Lu-DOTA-BR96 per kilogram of body weight and were sacrificed 2, 8, 24, 48, 72, 96, 120, or 168 h after injection, with activity measured in blood and tumor samples. Adjacent cryosections of each tumor were analyzed in 3 ways: imaging using a silicon-strip detector for digital autoradiography, staining for histologic characterization, or staining to determine the distribution of the antigen, vasculature, and proliferating cells using immunohistochemistry. Absorbed-dose rate distribution images at the moment of sacrifice were calculated using the activity distribution and a point-dose kernel. The correlations between antigen expression and both activity uptake and absorbed-dose rate were calculated for several regions of interest in each tumor. Nine additional animals with tumors were given unlabeled antibody to evaluate possible immunologic effects. Results: At 2-8 h after injection, activity was found in the tumor margins; at 24 h, in viable antigen-expressing areas within the tumor; and at 48 h and later, increasingly in antigen-negative areas of granulation tissue. The correlation between antigen expression and both the mean activity and the absorbed-dose rate in regions of interest changed from positive to negative after 24 h after injection. Antigennegative areas also increased over time in animals injected with unlabeled BR96, compared with untreated tumors. Conclusion: The results indicate that viable Lewis Y-expressing tumor cells are most efficiently treated during the initial uptake period. The activity then seems to remain in these initial uptake regions after the elimination of tumor cells and formation of granulation tissue. Further studies using these techniques could aid in determining the effects of the intratumoral activity distribution on overall therapeutic efficacy.