Abstract 3719: From gene to bedside: Mayo Clinic’s first-in-house BAFF-R CAR-T

Abstract Chimeric antigen receptor (CAR)-T cell therapy has revolutionized the treatment of B-cell malignancies. Despite the clinical success of CD19-targeted approaches, relapsed/refractory (R/R) disease—often driven by antigen loss or immune escape—remains a major challenge. To overcome this, we developed a novel CAR-T cell therapy targeting BAFF-R, a receptor consistently expressed in chronic lymphocytic leukemia (CLL) and other B-cell malignancies. We developed a new anti-BAFF-R monoclonal antibody and engineered the MC10029 CAR construct using its scFv. Antigen-specific cytotoxicity was validated in both in vitro and in vivo models, including Nalm-6 (leukemia) and Z138 (lymphoma), and CD19-knockout tumor cells to model (R/R) disease. MC10029 CAR-T cells were generated from healthy donors and CLL patients, and their cytotoxicity was evaluated against MEC-1, a CLL cell line, as well as autologous CLL patient tumor samples. These studies demonstrated potent and specific antitumor efficacy. We transitioned to clinical-grade production, using GMP-compliant lentivirus to manufacture MC10029 CAR-T cells under regulatory guidelines. With FDA IND approval, we initiated a Phase 1 clinical trial to evaluate safety and dosing. Our first patient, treated with a low-dose, single infusion, achieved a complete metabolic response within 2 months. The therapy is well tolerated, with no severe advent events such as cytokine release syndrome or neurotoxicity, supporting both the safety and efficacy of the therapy. Conclusion: This study represents Mayo Clinic’s first homegrown CAR-T cell therapy, developed entirely in-house—from antibody discovery and CAR design to GMP manufacturing and clinical trial—marking a significant step toward personalized, next-generation immunotherapy for B-cell malignancies. Citation Format: Yan Luo, Shaohua Guo, Yaqing Qie, Martha E. Gadd, Tanya Hundal, Hemant S. Murthy, Mohamed A. Kharfan-Dabaja, Hong Qin. From gene to bedside: Mayo Clinic’s first-in-house BAFF-R CAR-T [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2026; Part 1 (Regular Abstracts); 2026 Apr 17-22; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2026;86(7 Suppl):Abstract nr 3719.