Enhancing cancer immunotherapy with Anti-NKG2D/IL-15(N72D)/Sushi fusion protein: Targeting cytotoxic immune cells and boosting IL-15 efficacy.

Background: There are a number of distinct challenges and complexities associated with administering IL-15 for cancer immunotherapy that must be taken into consideration.

Objective: The purpose of this study was to design a fusion protein for targeting cytotoxic immune cells and enhance IL-15 efficiency.

Methods: A fusokine that contains IL-15(N72D), a Sushi domain, and anti-NKG2D scFv was designed. The fusion protein was in-silico modeled using the Swiss model server, followed by docking and molecular dynamics simulations. The in-vitro purified fusokine was evaluated using dot blot and Western blot. Then, flow cytometry was employed to evaluate biological properties such as proliferation, cytotoxicity, and degranulation.

Results: Fusokine and IL-15(N72D)/Sushi, which had molecular weights of about 52 kDa and 26 kDa, respectively, were expressed in CHO-K1 cells. The fusokine binds 69.6 % of the CHO-NKG2D cells that express 83.1 % NKG2D. Both the fusokine and the IL-15(N72D)/Sushi significantly stimulate the proliferation of lymphocytes. After 14 days of growth, the vitality of untreated cells decreased to about 17.5 %, but 82.2 % and 56.6 % of cells were still alive when fusokine and IL-15(N72D)/Sushi were present. Furthermore, administration of fusokine was associated with the highest rates of target tumor cell cytotoxicity. Additionally, although it was not statistically significant, fusokine increased the expression of CD107a and granzyme B by 1.25 times and 2.4 times, respectively.

Conclusion: The fusokine possesses the capability to stimulate the survival and multiplication of lymphocytes, as well as their ability to eliminate tumors. These characteristics have led to its consideration as a potential treatment for immunotherapy.