[PD-1 expression, mRNA level and cytotoxicity changes in CD19CAR-T cells]

Area of Science:

• Immunotherapy
• Oncology
• Cellular Therapy

Background:

• Programmed cell death protein 1 (PD-1) is a key immune checkpoint receptor.
• CAR-T cell therapy is a promising approach for treating various cancers, including lymphoma.
• Understanding PD-1 dynamics in CAR-T cells is crucial for optimizing therapeutic outcomes.

Purpose of the Study:

• To investigate changes in PD-1 expression, mRNA levels, and cytotoxic activity of CD19 CAR-T cells during culture.
• To evaluate the impact of high PD-1 expression in T-cell sources on CAR-T cell function.
• To assess the efficacy of PD-1 inhibitors in modulating CAR-T cell activity.

Main Methods:

• CAR-T cells were generated from T cells of lymphoma patients with high PD-1 expression and healthy volunteers.
• Flow cytometry, PCR, CCK-8, and LDH assays were used to analyze PD-1 expression, mRNA levels, proliferation, and cytotoxicity.
• CAR-T cells were cultured and co-cultured with lymphoma cells, with and without PD-1 inhibitors.

Main Results:

• Transfection efficiency and proliferation capacity of CAR-T cells were similar regardless of PD-1 expression levels or PD-1 inhibitor use.
• Cytotoxicity was significantly lower in CAR-T cells from high PD-1 expressors compared to healthy controls, but normalized with PD-1 inhibitor treatment.
• PD-1 expression on CAR-T cells increased upon contact with lymphoma cells, an effect reversed by PD-1 inhibitors, while mRNA levels remained unchanged.

Conclusions:

• CAR-T cells derived from high PD-1 expressing T cells exhibit reduced cytotoxicity, which can be restored by PD-1 inhibitors.
• While PD-1 protein expression increases after lymphoma cell contact, PD-1 mRNA levels remain stable, suggesting post-transcriptional regulation.
• PD-1 inhibitors hold potential for enhancing CAR-T cell therapy efficacy, particularly in patients with pre-existing high PD-1 expression.