Selective IL-1 activity on CD8⁺ T cells empowers antitumor immunity and synergizes with neovasculature-targeted TNF for full tumor eradication

Background Clinical success of therapeutic cancer vaccines depends on the ability to mount strong and durable antitumor T cell responses. To achieve this, potent cellular adjuvants are highly needed. Interleukin-1 beta (IL-1 beta) acts on CD8(+) T cells and promotes their expansion and effector differentiation, but toxicity and undesired tumor-promoting side effects hamper efficient clinical application of this cytokine. Methods This 'cytokine problem' can be solved by use of AcTakines (Activity-on-Target cytokines), which represent fusions between low-activity cytokine mutants and cell type-specific single-domain antibodies. AcTakines deliver cytokine activity to a priori selected cell types and as such evade toxicity and unwanted off-target side effects. Here, we employ subcutaneous melanoma and lung carcinoma models to evaluate the antitumor effects of AcTakines. Results In this work, we use an IL-1 beta-based AcTakine to drive proliferation and effector functionality of antitumor CD8(+) T cells without inducing measurable toxicity. AcTakine treatment enhances diversity of the T cell receptor repertoire and empowers adoptive T cell transfer. Combination treatment with a neovasculature-targeted tumor necrosis factor (TNF) AcTakine mediates full tumor eradication and establishes immunological memory that protects against secondary tumor challenge. Interferon-gamma was found to empower this AcTakine synergy by sensitizing the tumor microenvironment to TNF. Conclusions Our data illustrate that anticancer cellular immunity can be safely promoted with an IL-1 beta-based AcTakine, which synergizes with other immunotherapies for efficient tumor destruction.