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

## TL;DR

This paper compares two types of CAR-T therapies for B-cell cancers, focusing on how their signaling components affect treatment effectiveness and resistance.

## Contribution

The study highlights mechanistic differences between 4-1BB- and CD28-based CAR-T therapies and their impact on resistance mechanisms.

## Key findings

- CD19 loss is the main resistance mechanism after CD19-directed CAR-T therapy.
- CD28-based CAR-T cells are more potent, while 4-1BB-based CAR-T cells persist longer.
- CD28-based CAR-T therapy is less likely to select CD19low tumor cells compared to 4-1BB-based.

## Abstract

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.

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•CD19 loss is the dominant resistance mechanism after CD19-directed CAR-T therapy.•The costimulatory domain is one of the factors influencing the CAR-T cells' response.•CD28 CARs act more potently, while 4-1BB CARs persist longer.•CD28-based CAR-T therapy is less prone to select CD19low tumor cells than 4-1BB-based.

CD19 loss is the dominant resistance mechanism after CD19-directed CAR-T therapy.

The costimulatory domain is one of the factors influencing the CAR-T cells' response.

CD28 CARs act more potently, while 4-1BB CARs persist longer.

CD28-based CAR-T therapy is less prone to select CD19low tumor cells than 4-1BB-based.