Cancer antigens, antitumor activity

The conjugation of deacetylvinblastine to a monoclonal antibody that recognizes a tumor-associated antigen results in an agent with substantial antitumor activity in mice with relatively little toxicity (la). Conjugates of this type are of obvious interest for future clinical trials as site-directed cancer chemotherapeutic agents. 

The mechanism by which IFN-a exerts antitumor activity is unclear, particularly in hematological cancers. In melanoma and renal cell carcinoma, antitumor effects may be mediated by augmented immune responses including activation of natural killer lymphocytes and enhanced expression of cell surface antigens (e.g., MHC I and II). However, these mechanisms have not been decisively proved. 

Some of the recently isolated triterpenes possessed antitumor and cancer chemo-preventive activities. The chemopreventive activity was displayed in a mouse skin carcinogenesis assay, a UV-induced photocarcinogenesis assay in mice, and a TPA-induced Epstein-Barr vims early antigen activation assay in vitro. The antitumor activity was demonstrated in vitro in a panel of 39 human cancer cell lines. ... 

To review, in an experimental mouse model, LPDI/E7 vaccination both prevents the establishment of metastatic E7-expressing tumors in naive mice through an induced E7-specific T-cell immune response and, in mice with previously established E7-expressing tumors, causes tumor regression with one subcutaneous injection of LPDI/E7 [Han SJ, et al. Subcutaneous antigen loading of dendritic cells by liposome-protamine-DNA (LPD) nanoparticles results in their activation and induction of specific antitumor immune response (impublished)]. A robust immune response follows administration of LPDI/ peptide particles, which can be used as either a preventative or therapeutic cancer vaccination strategy due to the ability of the particles to prevent and eliminate tumors, respectively, in mouse models. 

Ethanolic extract (50%) of M. oleifera (whole plant excluding roots) shows anti-cancer activity in mice (50). Evaluation of the anticancer potential of 11 plants used in Bangladeshi folk medicine has shown that, only three extracts, among which M oleifera, is considered as a potential source of anticancer compounds (56). Crude ethanol extract of M. oleifera dried seeds inhibits the formation of Epstein-Barr virus-early antigen (EBV-EA) induced by 12-0-tetradecanoylphorbol-13-acetate. At a dosage of 100 pg/mL, the extract inhibits EBV-EA formation by 100% suggesting its antitumor-promoting activity (99). 

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