chTNT-3/hu IL-12 fusion protein for the immunotherapy of experimental solid tumors.
Fusion proteins are emerging as a promising approach for targeting cytokines to the tumor site in order to generate an effective anti-tumor response. In this study, a fusion protein, chTNT-3/huIL-12, consisting of the necrosis targeting antibody, chTNT-3, and human interleukin-12 (IL-12), was constructed and expressed using the glutamine synthetase gene amplification system in NS0 cells. For these studies, IL-12 was chosen since it has been shown to be a powerful anti-tumor cytokine. To generate the fusion protein, an expression vector was prepared by linking the huIL-12 p35 subunit cDNA to the 3' end of the chTNT-3 heavy chain cDNA and the p40 subunit was added to a separate vector. The activity of the expressed chTNT-3/huIL-12 was confirmed by standard IL-12 bioactivity assays which demonstrated that the fusion protein induced similar levels of peripheral blood lymphocyte (PBL) proliferation as free recombinant IL-12. In addition, the lytic activity of the fusion protein was demonstrated in both naive and IL-2-activated lymphocytes using cytotoxicity assays against three human pancreatic and prostatic cancer cell lines (CAPAN, DU145, and PC3-MA). Human PBL incubated with this fusion protein showed an increase in IFN-gamma production which was augmented dramatically by pre-incubation with IL-2. Finally, the immunotherapeutic potential of the fusion protein was demonstrated in the human PBL-SCID mouse model where a 44% reduction in DU145 prostatic tumor growth was obtained compared to control treated mice. These results demonstrate that tumor-targeted human IL-12 may be an effective immunotherapeutic reagent for the treatment of solid tumors in man.
Department of Pathology, University of Southern California Keck School of Medicine, Los Angeles, California 90033, USA.
Jiali
J
Li
Peisheng
P
Hu
Leslie A
LA
Khawli
Aoyun
A
Yun
Alan L
AL
Epstein
D000818:Animals; D001483:Base Sequence; D045744:Cell Line, Tumor; D017931:DNA Primers; D005260:Female; D006801:Humans; D007167:Immunotherapy; D018664:Interleukin-12 / Q000235:genetics / Q000627:therapeutic use*; D051379:Mice; D008807:Mice, Inbred BALB C; D016513:Mice, SCID; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000627:therapeutic use*
D017931:DNA Primers; D011993:Recombinant Fusion Proteins; D018664:Interleukin-12