Instructor Dartmouth College, New Hampshire, United States
Disclosure(s):
Yiji Liao, MD PhD: No financial relationships to disclose
Introduction/Rationale: Bladder cancer (BC) is immunogenic but remains poorly responsive to immunotherapy. Interleukin-2 (IL-2) stimulates cytotoxic lymphocytes but causes Treg expansion, toxicity, and rapid clearance. A CD122-directed IL-2 complex (IL-2c) can overcome these issues. To further optimize IL-2–based immunotherapy, we engineered two IL-2/anti-IL-2 antibody fusion proteins, F10 IC and F10 H9T, to differentially modulate effector and memory T-cell responses.
Methods: We fused the CD25-occluding antibody F10 to either native IL-2 (F10 IC) or an engineered IL-2 variant (H9T, Mo et al., Nature 2021). Antitumor efficacy was tested in an orthotopic MB49 bladder cancer model. Tumor growth, survival, and immune cell phenotypes were analyzed by flow cytometry, UMAP clustering, and IHC. Treatments included single agents, sequential combinations, and αPDL2 checkpoint blockade.
Results: F10 IC activated cytotoxic Teff and NK cells, whereas F10 H9T promoted CD44⁺CD62L⁺ central memory and Trm T-cell differentiation. Sequential or combined IL-2 variant therapy enhanced cytolytic activity and prolonged tumor control versus single agents. F10 IC plus αPDL2 significantly suppressed tumor growth and extended survival, while F10 H9T delayed relapse. UMAP analysis of TILs confirmed the predicted effector versus memory bias.
Conclusion: Distinct IL-2 fusion proteins can be strategically combined to harness effector and memory T-cell immunity. Integrating F10 IC and F10 H9T with checkpoint blockade represents a promising next-generation IL-2–based approach for durable tumor control in bladder cancer.
