Multi-mechanism armored B7H3/IL13Ra2 bispecific CAR-T for treatment of glioblastoma.

70 Background: Glioblastoma (GBM) is an aggressive and highly lethal cancer characterized by diffuse infiltration, molecular heterogeneity, immune evasion, and therapeutic resistance. Clinical outcomes remain poor due to antigen heterogeneity, an immunosuppressive tumor microenvironment, and limited access of targeted therapies across the blood–brain barrier. Despite early signals of activity with CAR-T therapy, sustained responses have not been achieved. We report the development of EPC-003, a fully human bispecific B7-H3/IL13Rα2 CAR-T product incorporating multi-mechanism armor to address antigen heterogeneity, reprogram the tumor microenvironment, and promote long-term persistence through central memory T-cell enrichment. Methods: A mechanism fine-tuned IL-2 variant with immune cell–type selectivity was discovered using a unique cytokine engineering platform and fused to an anti–PD-L1 scFv to generate a bispecific, multi-mechanism immune modulator. In parallel, target-binding scFvs against IL13Rα2 and B7-H3 were identified from proprietary human B-cell libraries using an mRNA display platform. Integration and optimization of these functional and binding modules yielded EPC-003, a bispecific tandem CAR targeting IL13Rα2, B7-H3, and incorporating a secreted multi-mechanism armor. EPC-003 mechanisms, antitumor potency, and preclinical safety were assessed. A scalable clinical manufacturing process was established to yield a central memory T cell–enriched CAR-T product. Results: The soluble armor demonstrated significant reduction of regulatory T-cell activation, while selectively activating central memory T-cells and mediating tumor infiltration lymphocytes in animal models, with the potential to improve CAR-T cell durability. In orthotopic GBM models, intracranial administration of low dose of EPC-003 (0.4 × 10⁶, 1.2 × 10⁶, 2 × 10⁶ CAR-T cells) induced tumor regression and showed dose-dependent anti-tumor activity. In a 7-day G-Rex manufacturing process, EPC-003 demonstrated promising druggability with robust and reproducible CAR expression, and the proprietary cytokine cocktail consistently enriched the product to >65% central memory CAR-T cells in normal donors and GBM patients. In preclinical toxicity studies, EPC-003 exhibited a favorable safety profile, with no body weight loss, cytokine release syndrome, or systemic clinical signs. No treatment-related pathological changes were observed across 25 examined organs. Immunohistochemistry revealed no evidence of brain hemorrhage in treated groups, with minimal monocyte infiltration in the pia mater observed only at the high dose. Conclusions: EPC-003, a multi-mechanism armored bispecific CAR-T, demonstrated favorable preclinical safety, developability, robust anti-tumor activity, and potential durability. These data had supported its advancement into clinical trial for the treatment of glioblastoma.