# Glycoengineering CAR-T cells to overcome galectin-3-mediated immunosuppression

## TL;DR

This study shows that modifying CAR-T cells to resist galectin-3 can improve their survival and effectiveness in fighting cancer.

## Contribution

The study introduces glycoengineering of CAR-T cells to enhance resistance to galectin-3-mediated immunosuppression.

## Key findings

- Galectin-3 is elevated in lymphoma microenvironments and binds to CAR-T cells.
- Enforcing ST6GAL1 expression blocks Gal-3 binding and reverses immunosuppressive effects.
- Modified CAR-T cells show improved anti-tumor activity and persistence.

## Abstract

Chimeric antigen receptor (CAR)-T cell therapy has transformed treatment for relapsed or refractory B-cell malignancies; however, limited in vivo persistence and treatment-limiting toxicities continue to constrain durable efficacy. Because T cell glycan signatures and related galectin-binding properties impact their effector function, we postulated that CAR-T cells similarly displayed signature glycan features that govern their vulnerability to immunosuppressive galectins. In this report, public data mining, galectin-binding and glycosyltransferase expression assessments and glycomics showed that galectin (Gal)-3 was elevated in lymphoma-associated microenvironments and that anti-CD19 CAR-T cells displayed abundant Gal-3-binding glycans, reduced expression of the Gal-3–inhibitory enzyme α2,6-sialyltransferase 1 (ST6GAL1), and heightened susceptibility to Gal-3–mediated immunoregulation. To further explore this association, we enforced ST6GAL1 expression in anti-CD19 CAR-T cells and found that Gal-3-binding was obstructed and Gal-3-mediated cell death and IL-5-induction were reversed. Enforcing ST6GAL1 in CAR-T cells did not weaken tumoricidal activity and significantly improved anti-tumor responses and in vivo persistence. Collectively, this study identifies Gal-3 as a key extrinsic suppressor of CAR-T cell function and establish targeted cell surface α2,6 sialylation as a strategy to enhance CAR-T cell resistance to galectin-rich immunosuppressive microenvironments.