The race between 4-1BB- and CD28-based CD19 CAR-T products in the therapy of B-cell malignancies.

Chimeric antigen receptor T-cell (CAR-T) therapy targeting CD19 has revolutionized the treatment of B-cell malignancies. One of the critical factors influencing CAR-T efficacy and durability is the costimulatory domain, with 4-1BB and CD28 emerging as the two dominant signaling platforms. While CD28-based CAR-T cells exhibit strong initial potency and rapid expansion, 4-1BB-based CAR-T cells demonstrate greater persistence and long-term efficacy. However, resistance to CAR-T therapy remains a significant challenge. Tumor cells develop a variety of mechanisms to evade immune surveillance, including CD19 antigen escape due to epigenetic factors or genetic aberrations of the CD19 gene. This review article summarizes the mechanistic differences between both costimulatory domains, their impact on clinical outcomes, and how they might influence resistance occurrence. By dissecting the battle of potency and the race of persistence, we provide insights into the evolving landscape of CAR-T therapy for B-cell malignancies.