A method of treating cancer is provided wherein the method comprises inhibiting or reducing sialylation of specifically Mesenchymal Stromal Cells (MSCs) to inhibit MSC immu nosuppression and restore T cell proliferation in cancer. The method may comprise administering a sialyltransferase inhibitor (eg 3Fax-Peracetyl Neu5Ac) or sialidase. Also described is administration of MSCs which have been manipulated prior to administration to remove sialic acids and use of a small molecule or blocking antibody which blocks interactions between MSC-sialic acid and lectins, such as Siglec 7, and or blocks interactions between MSC lectins and sialic acid.. Patent Number 16760379. U.S.A.