# Unique loop-structured CD19/CD22 bispecific CAR-T-cell therapy for patients with relapsed/refractory diffuse large B-cell lymphoma: an observational study

## TL;DR

A new CAR-T therapy targeting both CD19 and CD22 shows promise in treating hard-to-treat lymphoma by reducing antigen escape.

## Contribution

A novel loop-structured bispecific CAR-T design improves dual antigen targeting for lymphoma treatment.

## Key findings

- 80% of patients achieved complete remission with CD19/CD22 BS Loop CAR-T therapy.
- Treatment was well tolerated with minimal side effects like low-grade cytokine release syndrome.
- Three patients eventually experienced disease progression despite initial success.

## Abstract

Although CD19 and CD22 chimeric antigen receptor (CAR-T) cell therapies have demonstrated encouraging clinical responses in patients with B-cell lymphoma, over 50% of patients ultimately experience disease progression due to frequent antigen escape. The development of CD19/CD22 dual-target CAR-T cells holds promise for overcoming this limitation; however, their clinical application is currently challenging because of insufficient targeting of CD22.

In this study, we engineered CD19/CD22 BS Loop CAR-T cells with an enhanced targeting efficacy for CD22 and assessed their safety and effectiveness in patients with relapsed/refractory diffuse large B-cell lymphoma.

Among the five patients who received CD19/CD22 bispecific Loop CAR-T-cell therapy (1.6 × 106/kg) from December 2023 to May 2024, four patients (80%) achieved complete remission (CR), and one patient (20%) maintained a stable disease status 1 month after infusion. The expansion of the CD19/CD22 Beta-stranded (BS) Loop CAR-T cells was effective in vivo and detectable in the peripheral blood. All patients experienced only Grade 0–1 cytokine release syndrome without any observed neurotoxicity. With the follow-up extended to May 2025 (lasting for at least 1 year), three patients experienced disease progression and eventually died, while the remaining two patients remained in CR.

CD19/CD22 BS Loop CAR-T-cell therapy exhibits potent antilymphoma activity while addressing the challenges associated with designing CAR-T cells that are equally potent against two antigens. This treatment may represent a safe and effective unique immunotherapeutic strategy for lymphoma.

Statement of Significance
 A unique loop structure-based CD19/CD22 bispecific chimeric antigen receptor (CAR) increases dual-targeting efficacy.The CD19/CD22 BS Loop CAR addresses the challenge of insufficient CD22 targeting.CD19/CD22 BS Loop CAR-T cells were well tolerated and effective for r/r DLBCL.CD19/CD22 BS Loop CAR-T cell therapy represents a promising strategy for lymphoma.

A unique loop structure-based CD19/CD22 bispecific chimeric antigen receptor (CAR) increases dual-targeting efficacy.

The CD19/CD22 BS Loop CAR addresses the challenge of insufficient CD22 targeting.

CD19/CD22 BS Loop CAR-T cells were well tolerated and effective for r/r DLBCL.

CD19/CD22 BS Loop CAR-T cell therapy represents a promising strategy for lymphoma.

Graphical Abstract