Anti-tumoral potential of a human granulysin-based, CEA-targeted cytolytic immunotoxin

Oncoimmunology. 2019 Jul 22;8(11):1641392. doi: 10.1080/2162402X.2019.1641392. eCollection 2019.

Abstract

Granulysin is a protein present in the granules of human cytotoxic T lymphocytes (CTL) and natural killer (NK) cells, with cytolytic activity against microbes and tumors. Previous work demonstrated the therapeutic effect of intratumoral injection of recombinant granulysin using in vivo models of breast cancer and multiple myeloma. In the present work we have developed a granulysin gene fusion to the anti-carcinoembryonic antigen (CEA/CEACAM5) single chain Fv antibody fragment MFE23. Both granulysin and the granulysin-based immunotoxin were expressed in Pichia pastoris. The immunotoxin specifically recognized CEA, purified or expressed on the cell surface. Moreover, the bioactivity of the immunotoxin against several CEA+ cell lines was higher than that of granulysin alone. Granulysin and the immunotoxin were tested as a treatment in in vivo xenograft models in athymic mice. When injected intratumorally, both granulysin and the immunotoxin were able to inhibit tumor growth. Furthermore, systemic administration of the immunotoxin demonstrated a decrease in tumor growth in a CEA+ tumor-bearing mouse model, whereas granulysin did not exhibit a therapeutic effect. This is the first granulysin-based immunotoxin and the present work constitutes the proof of concept of its therapeutic potential.

Keywords: CEA; Granulysin; colon carcinoma; immunotoxin; scFv.

Publication types

  • Research Support, Non-U.S. Gov't

Grants and funding

This work was supported by the Ministry of Economics and Competitivity of Spain (SAF2016-76338-R to AA; CTQ2013-44367-C2-2-P and BFU2016-75633-P to RHG), by Carlos III HeaIth Institute, Spain, partially supported by European Regional Development FEDER funds (PI16-00357 to LS) and by Government of Aragon (B31_17R to AA and E34_17R to RHG), co-financed by FEDER 2014-2020 “Builiding Europe from Aragon”. The authors would also like to acknowledge the support of ARAID. RIP was supported by a predoctoral fellowship from Government of Aragon and PGO was supported by a Senescyt fellowship (Government of Ecuador).