IL2 and cancer: Moreover, prolonged treatment with high doses of IL-2 may result in T cell exhaustion and cancer progression due to Treg cells expansion.195,325 To address these issues, cytokine engineering approaches can be employed to modify IL-2 in a way that enhances the Teff-to-Treg cell ratio.326 This approach is essential for reducing side effects, boosting the effectiveness of immunotherapy, and decreasing the immunosuppressive effects caused by Treg cells.