IL2 and cancer: 1). Immune checkpoint blockade modalities targeting PD-1 and CTLA-4 provide long-lasting immune responses with established therapeutic benefits for some cancer patients (Refs 2–6). Although, targeting cytokines is considered a crucial approach in immunotherapy as evidenced in the treatment of solid tumours, such as renal cell carcinoma (RCC) and melanoma, only interferons (IFNs) and IL-2 have been approved by Food and Drug Administration (FDA) for use as cancer therapies (Ref. 7).