Abstract :
[en] Background Multiple myeloma (MM) is an incurable hematologic malignancy arising from clonal plasma cells, associated with dismal long-term outcomes due to inevitable relapse following conventional therapies. Chimeric antigen receptor (CAR) T-cell immunotherapy targeting B-cell maturation antigen (BCMA) has emerged as a transformative treatment, demonstrating remarkable efficacy in patients with relapsed disease. While conventional CAR constructs typically employ single-chain variable fragments (scFvs), single-domain antibodies (sdAb) offer an excellent alternative. Although numerous nanoCAR-T constructs have been developed, there is limited data comparing their functional activity. The aim of this research is to design and evaluate the activity of a new nanoCAR-T that compares well with a standard one with the conventional CAR-T CT103a.
Method We generated an anti-BCMA-VHH Nb17 and validated its BCMA binding ability on MM cell lines before incorporating it into a CAR sequence. A nanoCAR-T and a conventional CAR-T were produced by lentiviral transduction on primary T cells, and their killing capacity, cytokine production, degranulation, and memory function were compared in vitro in coculture with MM cell lines, and in vivo using a NSG mice model.
Results Nb17 bound strongly to BCMA expressed on MM cells and was integrated into a nanoCAR-T construct, which demonstrated specific killing capacity, cytokine production (IL-2, TFNa, IFNg) and degranulation (expression of CD107a) comparable to the clinically approved scFv-based CAR-T CT103a. Morevoer, Nb17-nanoCAR-T and this CT103a CAR-T express similar set of genes and pathways when co-cultured with MM cells, showed enhanced proliferation and displayed reduced exhaustion compared to untransduced T cells upon rechallenge with MM cells. In vivo, CT103a and nanoCAR-T cells eradicated MM1.S tumors, yet inducing graft-versus-host disease (GVHD)-like toxicity in a subset of mice.
Conclusion Our Nb17-nanoCAR-T demonstrates potent anti-myeloma efficacy in vitro as well as in vivo, and represents an attractive alternative, offering smaller size, greater stability, and potentially reduced immunogenicity.
