(840) Mechanisms of CD070, an Active Compound from Chinese Herbal Medicine, in Regulating and Inhibiting PD-1 Expression

Introduction/Rationale: PD-1 antibodies have shown clinical success in cancer treatment, but limitations such as limited efficacy, immune-related side effects, and high costs highlight the need for alternative approaches. There is an urgent need to identify new agents that inhibit PD-1 signaling and directly reduce its expression. This study aims to identify compounds that downregulate PD-1 expression on CD3-stimulated T cells and explore their mechanisms.

Methods: This investigation focused on CD070; a bioactive compound extracted from Chinese herbal medicine. We used CD3-stimulated Jurkat T cells and peripheral blood mononuclear cells (PBMCs), which were isolated from three different donors, to assess the effects of CD070 on PD-1 expression by Flow cytometry and Western blotting. Seahorse extracellular acidification rate (ECAR) analysis was used to assess glycolytic activity, and 2-deoxyglucose (2-DG), a glycolysis inhibitor, was added to investigate the role of glycolysis in PD-1 regulation.

Results: Our results showed CD070 treatment significantly downregulated PD-1 protein expression induced by CD3-stimulated Jurkat cells. In PBMCs from all donors, CD070 also reduced PD-1 expression across the CD3⁺, CD4⁺, and CD8⁺ T cell populations. Notably, Seahorse ECAR analysis revealed CD070 inhibited glycolysis in T cells in a dose-dependent manner. When using 2-DG, it similarly reduced PD-1 expression in CD3-stimulated T cells, supporting the connection between glycolysis and PD-1 regulation. Moreover, we found that increasing glucose concentrations in glucose-free culture media led to increased PD-1 expression, further reinforcing the idea that glucose metabolism plays a critical role in immune checkpoint regulation.

Conclusion: This study shows that CD070 reduces PD-1 expression on CD3-stimulated T cells by modulating glycolysis, offering a novel metabolic approach to enhance cancer immunotherapy.