GENETIC-ENGINEERING OF A RECOMBINANT FUSION POSSESSING ANTITUMOR F(AB')(2) AND TUMOR-NECROSIS-FACTOR

The construction, synthesis and expression of a genetically engineered bifunctional antibody/cytokine fusion protein is described. In order to target alpha-tumor necrosis factor (TNF) to tumor cells, recombinan t antibody techniques were used to construct an RM4/TNF fusion protein containing the chimeric anti-tumor F(ab')(2) (RM4) as well as the TNF moiety. The recombinant cDNA of human TNF was linked to the 3' end of the chimeric heavy-chain gene fragment (M4) containing the V-H, the C -H1 and the hinge region to form the fused heavy-chain gene fragment M 4-TNF. Transfection of the M4-TNF gene fragment into a VKCK cell line producing the chimeric light-chain of the same antibody allowed the tr ansfectant secreting the bifunctional fusion protein RM4/TNF. The RM4/ TNF was purified by affinity chromatography. Our data showed that RM4/ TNF retained the TAG72 antigen-binding reactivity as well as TNF activ ity as measured by ELISA, Western blotting, flow cytometry analysis, i mmunohistochemistry and cytotoxicity assays using the human colon canc er cell line LS174T. Therefore, the bifunctional fusion protein RM4/TN F may prove useful in targeting the biological effects of TNF to tumor cells, and in this way stimulate the immune destruction of tumor cell s. (C) 1997 Elsevier Science B.V.