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Although current demands for therapeutic mAbs are growing quickly, production methods to date, including in vitro mammalian tissue culture and transgenic animals, provide only limited quantities at high cost. Several tumor-associated antigens in tumor cells have been identified as targets for therapeutic mAbs. Here we describe the production of mAb BR55-2 (IgG2a) in transgenic plants that recognizes the nonprotein tumor-associated antigen Lewis Y oligosaccharide overexpressed in human carcinomas, particularly breast and colorectal cancers. Heavy and light chains of mAb BR55-2 were expressed separately and assembled in plant cells of low-alkaloid tobacco transgenic plants (Nicotiana tabacum cv. LAMD609). Expression levels of plant-derived mAb ([mAb.sup.P]) were high (30 mg/kg of fresh leaves) in [T.sup.1] generation plants. Like the mammalian-derived [mAb.sup.M], the plant [mAb.sup.P] bound specifically to both SK-BR3 breast cancer cells and SW948 colorectal cancer cells. The Fc domain of both [mAb.sup.P] and [mAb.sup.P] showed the similar binding to Fc[gamma]RI receptor (CD64). Comparable levels of cytotoxicity against SK-BR3 cells were also shown for both mAbs in antibody-dependent cell-mediated cytotoxicity assay. Furthermore, plant-derived BR55-2 efficiently inhibited SW948 tumor growth xenografted in nude mice. Altogether, these findings suggest that [mAb.sup.P] originating from low-alkaloid tobacco exhibit biological activities suitable for efficient immunotherapy. breast and colorectal cancer | plant biotechnology transgenic low-alkaloid tobacco | tumor growth inhibition

The tumor-associated antigen EpCAM (GA733-2) is a highly expressed target on adenocarcinoma cells, as defined by murine mAb CO17-1A. We recently developed a transgenic plant system for the safe and inexpensive production of large quantities of mAb CO17-1A as a future source of clinical-grade protein. Although the glycosylation pattern of plant-derived mAb ([mAb.sup.P]) CO17-1A differs considerably from that of the mammalian-derived mAb ([mAb.sup.M]), we show here that the biological activity of both mAbs is quite similar, [mAb.sup.P] heavy and light chains assembled to bind the recombinant antigen GA733-2E and specifically bound to human SW948 colorectal carcinoma cells expressing the antigen GA733-2 to the same extent as [mAb.sup.M] x [mAb.sup.P] was as effective as [mAb.sup.M] CO17-1A in inhibiting tumor growth of xenotransplanted SW948 cells in nude mice. These results suggest the promise of transgenic plants as a useful alternative way to produce full-size mAb for cancer immunotherapy. endoplasmic reticulum | glycosylation | Lys-Asp-Glu-Leu | mammalian-derived mAb

DNA synthesis and PCR on total RNA extracted from human colon tissues revealed 40- and 340-fold increases in mRNA transcript levels for the human H gene-encoded beta-D-galactoside alpha-2-L-fucosyltransferase in adenocarcinomas and tumor cell lines compared to normal colon mucosa. DNA sequence analysis of the plasmid insert in the protein coding region of the cDNAs from normal colon, adenoma and colon adenocarcinoma revealed 100% homology. These results suggest that beta-D-galactoside alpha-2-L-fucosyltransferase expression is correlated with the development of colon adenocarcinoma.