Multiple myeloma (MM), the second most common blood cancer, is characterized by the accumulation of malignant plasma cells in the bone marrow. Chimeric Antigen Receptor (CAR)-T cell therapy has recently entered the standard of care for relapsed and refractory MM, following the recent FDA-approval of two CAR-T cell products, ide-cel® and cilta-cel®, which target the B cell maturation antigen (BCMA). However, despite impressive response rates, most patients relapse within 1-3 years. Kappa (κ) myeloma antigen (KMA) is a tumour specific membrane associated protein expressed on malignant plasma cells in patients with kappa light-chain restricted (κ-type) MM. KMA is absent on normal plasma cells and haematopoietic stem cells, making it an attractive and alternative target antigen for CAR-T cell therapy for MM. The monoclonal antibody, KappaMab (MDX-1097), binds to a conformational epitope on KMA, and has been assessed in phase I, IIa and IIb clinical trials in relapse refractory myeloma patients (1). Here, we have engineered a lentiviral vector encoding a second-generation CAR expressing a scFv from MDX-1097, fused to a 4-1BB co-stimulatory domain and CD3 zeta chain. We successfully generated human anti-KMA CAR-T cells with high and stable CAR expression and a predominately memory T cell phenotype. The CAR-T cells selectively killed KMA-expressing tumour lines, secreted interferon-gamma upon target recognition, and demonstrated potent anti-tumour activity in a xenograft model. Anti-KMA CAR-T cell therapy therefore represents a novel and potent treatment ready to enter a phase I clinical trial for patients with myeloma. (1) Spencer et al. Blood Cancer Journal (2019) 9:58

Citation Format: Jessica Li, Nicole Haynes, Katherine Cummins, Kavitha Gowrishankar, Kenneth Micklewaithe, Halley Hilton, Rosanne Dunn, Jane Oliaro, Simon Harrison. Cellular immunotherapy targeting kappa myeloma antigen for the treatment of multiple myeloma. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4074.