No abstract

The Interleukin-2 Family contains six kinds of cytokines, namely IL-2, IL-15, IL-4, IL-7, IL-9, and IL-21, all of which share a common γ chain. Many cytokines of the IL-2 family have been reported to be a driving force in immune cells activation. Therefore, researchers have tried various methods to study the anti-tumor effect of cytokines for a long time. However, due to the short half-life, poor stability, easy to lead to inflammatory storms and narrow safety treatment window of cytokines, this field has been tepid. In recent years, with the rapid development of protein engineering technology, some engineered cytokines have a significant effect in tumor immunotherapy, showing an irresistible trend of development. In this review, we will discuss the current researches of the IL-2 family and mainly focus on the application and achievements of engineered cytokines in tumor immunotherapy.

Siglec-15 is an important immunosuppressive molecule considered to be a key target in next generation tumor immunotherapy. In this study, we screened 22 high affinity antibodies that specifically recognize human Siglec-15 by using a large human phage antibody library and 5 representative sequences were selected for further study. The results showed the binding activity of 5 antibodies to Siglec-15 (EC 50 ranged from 0.02368μg /mL to 0.07949 μg /mL) and in 2 Siglec-15 overexpressed cell lines, 3 antibodies had the strongest binding activity, so the 2 clones were discarded for further study. Subsequently the affinity of 3 antibodies were measured by Bio-layer interferometry technology (5-9×10E-09M). As the reported ligands of Siglec-15, the binding activity of Siglec-15 and sialyl-Tn, CD44, MAG and LRRC4C can be blocked by 3 of the antibodies. Among these, 3F1 had a competitive advantage. Then, the antibody 3F1 showed an obvious ADCC effect (EC 50 were 0.85 μg/mL). Further, antibody 3F1 can reverse the inhibitory effect of Siglec-15 on lymphocyte proliferation (especially CD4 + T, CD8 + T) and cytokine release (IFN-γ).Given the above results, 3F1 was selected as a candidate for the in vivo pharmacodynamics study. In the tumor model of Balb/c Nude mice, 3F1 (10 mg/kg) showed certain anti-tumor effects (TGI was 31.5%) while the combination of 3F1 (5 mg/kg) and ERBITUX (5 mg/kg) showed significant antitumor effects (TGI was 48.7%) compared with the PBS group. In conclusion, novel human antibody 3F1 has This article has not been copyedited and formatted. The final version may differ from this version.