Rewiring STAT signaling from the cell surface with Trikine immunotherapeutics.

Cytokines dimerize two receptor chains to activate Janus kinases and STAT transcription factors that regulate immune cells but have therapeutic liabilities. We engineered "Trikines" to compel cis formation of three-chain cytokine receptor complexes at the cell surface that induce bespoke STAT transcriptional signaling programs. Trikines co-activated pSTAT5 and pSTAT3 signatures distinct from natural cytokines, by assembling trimeric combinations of Interleukin-2 (IL-2), Interleukin-10 (IL-10), and Interleukin-21 (IL-21) receptors. In pre-clinical models, an IL-2-based-Trikine restrained terminal differentiation of T cells, promoted stemness, and enhanced durability of tumor control without observable toxicity. An IL-10-based Trikine induced immune infiltration into poorly immunogenic tumors, showing efficacy in pre-clinical models of small cell lung cancer and pancreatic cancer. Trikines obviate the need for cell engineering to customize STAT signatures and may hold potential for immunotherapy.