Long-acting IL-7 induces distinct transcriptomic features in peripheral T cells of patients with solid tumors

BACKGROUND: IL-7 is a critical cytokine in T cell development, survival, and homeostasis. Previous preclinical and clinical studies reported that IL-7 treatment increased T cell counts, but its effect on peripheral blood T cells in cancer patients and molecular mechanisms have not been explored. METHODS: We investigated effects of long-acting recombinant human interleukin-7 (rhIL-7-hyFc) on peripheral T cells in patients with advanced solid tumors. Peripheral blood samples were collected before and after treatment, followed by analysis through single-cell transcriptomics and flow cytometry. RESULTS: We found that rhIL-7-hyFc induced marked expansion of proliferating T cells, and promoted transcriptional changes associated with immune activation, cell cycle progression, and anti-apoptosis. Trajectory analysis revealed that post-treatment T cells had distinct transcriptional states enriched for cytokine- and TCR-mediated signaling pathways. Notably, a second dose administered after three weeks yielded diminished proliferation and minimal transcriptional changes, which were independent of antidrug antibody or CD127 downmodulation. Examination of elements of the IL-7 signaling pathway revealed intact proximal signaling (e.g., STAT5 phosphorylation) but downregulation of distal elements, including PIM-1 kinase and c-Myc. CONCLUSIONS: Our results demonstrate that rhIL-7-hyFc induces robust peripheral T-cell expansion and activation in patients with solid tumors, supporting its potential use for lymphopenic patients treated with cancer immunotherapy. TRIAL REGISTRATION: NCT03478995, NCT03619239. FUNDING: NRF-2022R1A2C3007292, RS-2024-00439160, RS-2025-02213409, RS-2025-25460003 .