5-Fluorouracil resistance due to sphingosine kinase 2 overexpression in colorectal cancer is associated with myeloid-derived suppressor cell-mediated immunosuppressive effects.

Our findings suggest that 5-FU treatment combined with simultaneous Spkh2 inhibition by ABC294640 has anti-tumor synergistic effects by influencing multiple effects on tumor cells, T cells, and MDSCs, potentially improving the poor prognosis of colorectal cancer patients.