Abstract Rationale Eosinophil-mediated inflammation plays a central role in various respiratory diseases, including severe asthma, chronic eosinophilic pneumonia, and allergic bronchopulmonary aspergillosis. While current treatments such as corticosteroids and immunosuppressants provide temporary symptom relief, their limited efficacy and significant side effects highlight the need for more effective therapies. Dysregulated interleukin-5 (IL-5) signaling, which promotes eosinophil survival and proliferation through its interaction with IL-5 receptor α (IL-5Rα), is a key driver of disease progression. Targeted inhibition of the IL-5/IL-5Rα pathway emerges as a promising therapeutic strategy to address the limitations of conventional approaches and improve clinical outcomes in these treatment-refractory conditions. Methods We developed a novel CAR-T cell therapy strategy targeting this pathway, utilizing human IL-5 as the antigen-binding domain to selectively eliminate pathogenic eosinophils and their progenitors. To bridge preclinical discovery with therapeutic applications, we established a Good Manufacturing Practice (GMP)-grade manufacturing process for clinical-grade hIL-5 CAR-T cells using optimized protocols to ensure product consistency, quality, and safety. In vitro functional assessments included cytotoxicity analysis using luminescent cell viability assays and IFNγ secretion profiling. In vivo efficacy was evaluated in NCG mice engrafted with IL-5Rα-positive human eosinophilic leukemia (HES/CEL) xenografts. Safety was tested via soft agar colony formation assays, tumorigenicity studies in nude mice, and systemic toxicity assessments (histopathology, hematology, cytokine profiling). Results IL-5 CAR-T cell therapy demonstrates significant therapeutic potential through a dual-action mechanism, effectively targeting both mature eosinophils in circulation and their progenitors in the bone marrow. In vitro analyses demonstrated potent cytotoxicity against IL-5Rα-positive cell populations, with robust IFNγ secretion, indicating T-cell activation. In vivo evaluations using HES/CEL xenograft models showed sustained tumor regression and significant survival extension following a single-dose administration, suggesting durable therapeutic effects. Rigorous clinical-scale manufacturing protocols have been established to ensure reproducible clinical-grade production, with safety assessments confirming no dose-limiting toxicities or treatment-related organ damage. Conclusion The IL-5 receptor-targeted chimeric antigen receptor T-cell (CAR-T) therapy holds significant promise for treating refractory eosinophil-driven respiratory diseases, such as severe asthma, eosinophilic granulomatosis with polyangiitis, and hypereosinophilic syndromes. This novel approach provides a dual therapeutic advantage: precise depletion of pathogenic eosinophils leading to sustained disease remission and a favorable safety profile, with no observed cytokine release syndrome or off-target cytotoxicity. By expanding CAR-T cell therapy beyond hematologic malignancies, it introduces a transformative treatment paradigm for eosinophil-mediated pathologies, offering significant potential for clinical translation in managing severe allergic and autoimmune respiratory diseases. This abstract is funded by: Key R&D Program of Zhejiang Province (2023C03022, 2023C03009), National Key R&D Program of China (2021YFA1102001), Natural Science Foundation of China (82225001, 82430002, 82370026, 82203508).
Zhang et al. (Fri,) studied this question.