Arnold Lockshin

Prediction of anticancer activity by tumor uptake of radiolabeled monoclonal antibody

A novel and sensitive method is described for rapid detection of anticancer drug efficacy against human tumor xenografts in nude mice. CA or BRO human melanoma cells were inoculated i.m. in nude mice, which then were treated with saline or cytotoxic agents. After injection of 111In-labeled 9.2.27 antimelanoma monoclonal antibody, the site of tumor inoculation and the contralateral non-tumor site were excised from sacrificed mice. Relatively lower 111In uptake in the area of tumor inoculation correlated with prevention or delay of tumor growth in identically treated counterpart mice.

Lethality of human melanoma cells for normal mice immunosuppressed with cyclosporin A

After intraperitoneal inoculation of BRO human melanoma cells, phenotypically immunocompetent mice given cyclosporin A (CyA) developed extensive and lethal tumors. Survivals were not significantly different for normal mice treated with this immunosuppressant compared to nude mice, which lack functional T-lymphocytes. BRO cells could be passaged in CyA-treated mice without alteration of isozymes or other properties tested. This model may have implications for growth and metastasis of human tumors under immunosuppressed conditions and may be useful for studying the mechanism of action of CyA in vivo.

Determination of cytotoxicity in vivo using 111indium-labeled human tumor cells

Loss of radioactivity from nude mice was determined after inoculation of human tumor cells prelabeled with [111In]indium oxine (111InOx). Elimination of 111In was increased somewhat by treating the mice with diphtheria toxin (DT), which is toxic selectively for human cells compared to mice. Calcium disodium edetate (CaNa2EDTA), a metal chelating agent, facilitated elimination of 111In and increased the difference in the rates of loss of radioactivity from mice bearing viable compared to DT-killed cells.

Quantitative evaluation of anticancer agents against human melanoma cells implanted in nude mice

BRO human melanoma cells, which are exceptionally tumorigenic and lethal for nude mice, were inoculated intraperitoneally or intracerebrally in varying numbers. An inverse linear correlation was observed between the logarithm of the number of cells inoculated and host survival. In mice bearing 10(7) cells intraperitoneally, 2.4-2.8 log10 units of cell kill were obtained after a single intraperitoneal injection of vincristine, and some mice inoculated with 10(5) cells were cured by this treatment. Fewer cells were killed by L-phenylalanine mustard. Vincristine did not prolong survival of nude mice with intracerebral BRO tumors. Cell kill after administration of anticancer agents can be quantitated for BRO cells inoculated intraperitoneally or intracerebrally.

Improved tumor localization of 111In labeled monoclonal antibody with chelator administration to host nude mice

Administration of calcium disodium edetate (EDTA) substantially increased the tumor:muscle ratios of nude mice injected with 111In labeled monoclonal antibody injection of mice bearing the BRO human melanoma, but not earlier. The tumor:muscle ratios decreased during this time for animals not receiving chelator. Contemporaneously, EDTA treated mice lost whole body radioactivity more rapidly than did their untreated counterparts, suggesting that 111In which had dissociated from the antibody-DTPA-radiometal complex was chelated and excreted. These results suggest that effective chelator treatment might improve tumor localization of radioactivity after injection of 111In labeled antibodies.

111Indium Labeling of Cultured Human Tumor Cells

At least one microCi of 111indium oxine (111InOx) could be incorporated into 10(6) human tumor cells without cytotoxicity as determined by colony assay or by trypan blue staining. 111In bound to prekilled cells was removed preferentially by washings, and prelabeled cells killed with diphtheria toxin released radioactivity much more rapidly than did viable cells. The metal chelator calcium disodium edetate did not facilitate 111In removal from either viable or dead cells. High sensitivity can be obtained for in vitro or in vivo cytotoxicity assays using human cells prelabeled with 111InOx.

In vivo cytotoxicity assays with 111In-labeled tumor cells: Comparison with [125I]iododeoxyuridine-labeled cells and effects of chelators and inoculation site

The fate of cells inoculated in nude mice can be determined using human tumor cells prelabeled with 111In oxine (111InOx). To facilitate elimination of extracellular 111In released from killed cells, an appropriate metal chelating agent is administered to the host mice. With calcium disodium edetate administered by various routes, highly significant differences in the rates of 111In loss were observed for viable compared to killed cells after i.p. or i.m. inoculation. Radioactivity was eliminated at similar rates for mice bearing viable cells labeled with 111In or with [125I]iododeoxyuridine (125IUdR). For killed cells, 111In was eliminated somewhat less efficiently than 125I. The 111In-prelabeling method allows facile and sensitive determination of host-mediated cytotoxicity for inoculated tumor cells.