Attenuated IL-2 Signaling Rewires Transcriptional and Metabolic Programs in T Cells to Enable Coupling Proliferation and Stemness

Interleukin-2 (IL-2) is a fundamental cytokine that controls the proliferation and differentiation of T cells1. Its direct administration in vivo has conferred durable, complete responses in patients with metastatic melanoma and renal cell cancer, while it is also used to expand tumor-infiltrating lymphocytes (TILs) in vitro for adoptive cell therapy (ACT)2. Unfavorable properties of IL-2 including terminal differentiation of effector T cells3-6, induction of activation-induced cell death (AICD)2, 7, 8, expansion of regulatory T (Treg) cells, and toxicity at high doses, have driven the development of IL-2 variants with modified biological properties9-13. However, how cytokine modifications alter cell fate decisions is not well understood. Here, taking a systems biology approach we have comprehensively elucidated how a non CD25-binding, IL-2-biased agonist (IL-2v)14 reprograms signaling, transcriptional, and metabolic networks of CD8+ T cells in vitro to favor stemness while simultaneously driving expansion and functionality. Such "expansion-stemness state" defines metabolically fit CD8+ T cells capable of superior persistence and tumor control. These findings broaden our fundamental understanding of the effects of IL-2v on T-cell biology and provide an investigational framework for the rational development and evaluation of cytokine variants with clinical relevance.