High-Density Wild-Type IL-2 Nanoparticles Preferentially Enhance CD8⁺ T-Cell Expansion and Reprogram the Tumor...

Area of Science:

• Immunology
• Nanotechnology
• Oncology

Background:

• Low response rates to immune checkpoint inhibitors (ICIs) in solid tumors are linked to insufficient tumor-infiltrating CD8+ T cells and an immunosuppressive tumor microenvironment (TME).
• Interleukin-2 (IL-2) effectively expands and activates CD8+ T cells but faces clinical limitations including rapid clearance, dose-limiting toxicity, and regulatory T cell (Treg) stimulation.
• Engineered IL-2 variants have yet to demonstrate significant clinical efficacy.

Purpose of the Study:

• To develop a nanoparticle-based delivery system for IL-2 to overcome its clinical limitations.
• To enhance CD8+ T cell responses and improve the efficacy of cancer immunotherapies.

Main Methods:

• Development of polymer-modified mesoporous silica nanoparticles displaying dense, wild-type IL-2 on their surface (IL2-NP).
• Evaluation of IL2-NP's ability to confer proteolytic stability, tumor retention, and avidity-mediated CD8+ T cell binding.
• Assessment of IL2-NP's impact on TME reprogramming, including dendritic cell activation and M1-like macrophage polarization.
• Testing IL2-NP's efficacy in combination with ICIs in preclinical cancer models.

Main Results:

• IL2-NP enhances CD8+ T cell proliferation and effector function without increasing Treg binding or proliferation.
• Intratumoral IL2-NP treatment expands CD8+ T cells, increases CD8+/Treg ratios, and reprograms the TME.
• IL2-NP treatment induces regression of both treated and untreated tumors in a CD8+ T cell-dependent manner.
• IL2-NP synergizes with ICIs, leading to complete tumor regression and the establishment of immunological memory.
• Treatment with IL2-NP is well-tolerated and effective in triple-negative breast and metastatic ovarian cancer models.

Conclusions:

• Intratumoral IL2-NP elicits robust systemic antitumor immunity by enhancing CD8+ T cell responses and reprogramming the TME.
• IL2-NP represents a promising strategy to improve the efficacy of ICIs, cancer vaccines, and adoptive T-cell therapies.
• This nanoparticle platform overcomes key limitations of IL-2 immunotherapy, offering a potential new avenue for cancer treatment.