No abstract

A fusion protein containing a B cell lymphoma idiotype (Id) variable genes from the tumor and the preparation of and granulocyte-macrophage colony-stimulating factor tumor-specific vector constructs. The low production of (GM-CSF) is a potent stimulator of tumor immunity. In three Id/GM-CSF fusion proteins by transfected cells, which is different tumor models we show that immunization with a major obstacle in the use of purified fusion proteins for autologous lymphoma cells that have been engineered to immunotherapy, is due to the presence of the cytokine express the Id in the context of GM-CSF is much more gene in the immunoglobulin locus. Low production, howeffective than immunization with an equivalent dose of the ever, is not limiting in the cell-based setting, because upon purified protein. The lymphoma Id could be modified by in vivo administration of the modified autologous cells, introducing the GM-CSF gene into the immunoglobulin (Ig) even minute expression levels are sufficient to induce heavy chain locus via gene targeting. This approach cirtumor immunity. cumvents the isolation of the rearranged immunoglobulin

The trioma approach is a new immunotherapeutic strategy for treating B‐cell lymphomas. It is based on converting the tumour idiotype to a bispecific immunoglobulin that redirects the idiotype to antigen‐presenting cells. We show here that even pre‐existing tumours can be eradicated by trioma vaccination, that the trioma approach is superior to vaccination with cytokine gene‐modified autologous tumour cells and that there is a synergism between trioma immunisation and GM‐CSF gene transfer. Furthermore, we show that the immunising potential of GM‐CSF gene‐modified autologous lymphoma cells is not as dependent on the cytokine expression level as described for other tumour models, such that even minute expression rates are effective. IL‐4 gene transfer in the lymphoma model is considerably less efficient or even ineffective when more sensitive systems are used. Remarkably, trioma‐mediated effects are extinguished when IL‐4 is expressed by the trioma cell. Int. J. Cancer 83:113–120, 1999. © 1999 Wiley‐Liss, Inc.

The trioma approach is a new immunotherapeutic strategy for treating B-cell lymphomas. It is based on converting the tumour idiotype to a bispecific immunoglobulin that redirects the idiotype to antigen-presenting cells. We show here that even pre-existing tumours can be eradicated by trioma vaccination, that the trioma approach is superior to vaccination with cytokine gene-modified autologous tumour cells and that there is a synergism between trioma immunisation and GM-CSF gene transfer. Furthermore, we show that the immunising potential of GM-CSF gene-modified autologous lymphoma cells is not as dependent on the cytokine expression level as described for other tumour models, such that even minute expression rates are effective. IL-4 gene transfer in the lymphoma model is considerably less efficient or even ineffective when more sensitive systems are used. Remarkably, trioma-mediated effects are extinguished when IL-4 is expressed by the trioma cell. Int.

Immunization with modified immunoglobulin (Ig) idiotypes (Ids) of B-cell lymphomas is an attractive approach of experimental tumor immunotherapy. We show here that B-lymphoma cells can be gene-modified by homologous recombination at the Ig heavy chain locus. Although it has been demonstrated previously that a protein vaccine containing a mouse/human chimeric Ig had no immunostimulatory effect, we show that a xenogeneic Fc segment attached to the Id by gene targeting in autologous murine tumor cells can serve as an immunogenic carrier and is capable of inducing tumor protection. A prerequisite for successful vaccination is the delivery of tumor cells that have been engineered to express the Id in the chimeric form rather than administration of the soluble chimeric protein. Also DNA vaccination with plasmids encoding chimeric Ids was reported to induce an anti-idiotypic response, suggesting that there might be related mechanisms such as enhanced antigen presentation. Immunization with engineered lymphoma cells is a very potent protocol: in the cell-based setting, minute levels of expression in the gene-targeted cells are sufficient to confer tumor immunity. Because the titers of anti-Id antibodies induced do not reflect the degree of tumor protection, the immune mechanisms responsible for tumor rejection cannot be ascribed exclusively to a humoral response. Cancer Gene Therapy (2000) 7, 501-506