Regulatory T cell (Treg) is an immune regulatory cell population that helps control immune activation and tolerance, and its activation can contribute to IL-2 clinical toxicity. In cancer, Tregs are a major component of the suppressive tumor microenvironment, where they can blunt antitumor immunity; this was highlighted in a lymphoma study of an IL-18-armed oncolytic vaccinia virus that modulated Tregs and macrophages. In immunotherapy, unwanted Treg activation is a limitation of IL-2-based approaches, including PD-1–IL-2 bispecific agents designed to reshape cytokine signaling while avoiding excessive regulatory-cell expansion. In autoimmunity, Treg immune modulation is being explored as a therapeutic strategy for type 1 diabetes, alongside gene therapy and CRISPR-based β-cell replacement approaches. Overall, Tregs are a key immunoregulatory target across cancer and autoimmune disease, with recent work focusing on selectively modulating their suppressive function rather than broadly depleting them.
Cancer
- Tregs were described as part of the suppressive tumor microenvironment in lymphoma, where they may limit antitumor immune responses. A 2026 Cancer Immunology, Immunotherapy study of an IL-18-armed oncolytic vaccinia virus reported microenvironment remodeling via macrophage and Treg modulation. (PMID:42012649)
- The vaccinia-virus therapy was specifically noted to modulate Tregs in the suppressive microenvironment, linking vaccinia virus to immune reprogramming in lymphoma. (PMID:42012649)
- A 2026 BioDrugs review on PD-1–IL-2 bispecific agents discussed Treg activation as an unwanted effect that can constrain cancer immunotherapy. (PMID:41973150)
- IL-2 therapy was described as limited by unwanted activation of the Treg population, underscoring the challenge of balancing effector stimulation with regulatory-cell expansion. (PMID:41973150)
Autoimmune disease
- Treg immune modulation approaches were discussed as a strategy for type 1 diabetes, reflecting their role in restoring immune tolerance. A 2026 Diabetes, Obesity & Metabolism paper covered gene therapy and gene editing in type 1 diabetes mellitus. (PMID:42023429)
- The type 1 diabetes article paired Treg modulation with CRISPR-based β-cell replacement, suggesting combination strategies for immune control and cell replacement. (PMID:42023429)
- Tregs were framed as a therapeutic immune-regulatory population rather than a direct disease target, with modulation intended to rebalance autoimmunity. (PMID:42023429)