Specific Targeting of Zinc Transporter LIV-1 with Immunocytokine Containing Anti-LIV-1 VHH and Human IL-2 and Evaluation of its In vitro Antitumor Activity.

Abstract

Interleukin 2 (IL-2) is a vital cytokine in the induction of T and NK cell responses, the proliferation of CD8+ T cells, and the effective treatment of human cancers, such as melanoma and renal cell carcinoma. However, widespread use of this cytokine is limited due to its short half-life, severe toxicity, lack of specific tumor targeting, and activation of Treg cells mediated by high-affinity interleukin-2 receptors. In this study, a tumor-targeting LIV-1 VHH-mutIL2 immunocytokine with reduced CD25 (α chain of the high-affinity IL-2 receptor) binding activity was developed to improve IL-2 half-life by decreasing its renal infiltration in comparison with wild and mutant IL-2 molecules. The recombinant immunocytokine was designed and expressed. the biological activity of the purified fusion protein was investigated in in vitro and in vivo experiments. The fusion protein represented specific binding to MCF7 (the breast cancer cell line) and more efficient cytotoxicity than wild-type IL-2 and mutant IL-2. the PK parameters of the recombinant immunocytokine were also improved in comparison to the IL-2 molecules. The observed results showed that LIV1-mIL2 immunocytokine could be considered an effective agent in the LIV-1-targeted treatment of cancers due to its longer half-life and stronger cytotoxicity.