Potent antitumor activity of a designed interleukin-21 mimic

Area of Science:

• Immunology
• Oncology
• Biotechnology

Background:

• Cancer immunotherapy aims to enhance cytotoxic T cell responses while reducing regulatory T cell activity, but current methods have limitations.
• Interleukin-21 (IL-21) is a cytokine involved in immune regulation and T cell function, but its therapeutic application is constrained by stability and potency issues.

Purpose of the Study:

• To develop and evaluate a novel, stable, and potent IL-21 mimic (21h10) for cancer immunotherapy.
• To assess the antitumor efficacy and immune-modulating effects of 21h10 in preclinical models and human tumor samples.

Main Methods:

• Design and synthesis of a de novo IL-21 mimic (21h10) with enhanced stability and signaling potency.
• Evaluation of 21h10's antitumor activity in multiple animal cancer models and ex vivo human melanoma patient-derived organotypic tumor spheroids (PDOTS).
• Analysis of STAT signaling, T cell responses (cytotoxic and regulatory), and cytokine production in the tumor microenvironment following 21h10 administration.

Main Results:

• 21h10 demonstrated robust antitumor activity across various models, significantly outperforming native IL-21.
• The mimic induced prolonged STAT signaling in vivo and expanded low-affinity cytotoxic T cells, enhancing interferon-gamma (IFN-γ) and granzyme B expression.
• 21h10 increased IFN-γ+ Th1 cells and decreased Foxp3+ regulatory T cells (Tregs) within the tumor microenvironment.
• Systemic toxicity associated with 21h10 was manageable with TNFα blockade without compromising efficacy.

Conclusions:

• The IL-21 mimic 21h10 represents a promising therapeutic agent for cancer immunotherapy due to its potent activation of diverse antitumor T cells and suppression of Tregs.
• 21h10's cross-reactivity, stability, potency, and ability to potentiate low-affinity T cell responses offer significant translational potential for clinical applications.