Polysialylated CD56 drives immune evasion in clear cell renal cell carcinoma via engagement of the Siglec-7 checkpoint on CD8+ T cells

T cells, suppressing the production of IFN-γ and TNF-α and promoting T cell apoptosis. Importantly, blocking the PSA-CD56/Siglec-7 interaction with specific antibodies restored T cell effector functions and triggered apoptosis of ccRCC cells. Our study unveils the PSA-CD56/Siglec-7 axis as a novel glyco-immune checkpoint, which represents a promising target for therapeutic interventions in ccRCC.