Immune cell-based cancer therapies, such as chimeric antigen receptor T (CAR-T)-cell immunotherapy, have demonstrated impressive potency against hematological tumors. However, the efficacy of CAR-T cells against solid tumors remains limited. Herein, we designed tumor-targeting molecule-sialidase conjugates that potently and selectively stripped different sialoglycans from a variety of cancer cells. Desialylation enhanced induced pluripotent stem cell-derived chimeric antigen receptor-macrophage (CAR-iMac) infiltration and activation. Furthermore, the combination of cancer cell desialylation and CAR-iMac adoptive cellular therapy exerted a dramatic therapeutic effect on solid tumors and significantly prolonged the survival of tumor-bearing mice; these effects were mainly dependent on blockade of the checkpoint composed of sialic acid-binding immunoglobulin-like lectin (Siglec)-5 and Siglec-10 on the macrophages, and knockout of the glycoimmune checkpoint receptors could construct a CAR-iMac cell with stronger anticancer activity. This strategy that reverts the immune escape state ("cold tumor") to a sensitive recognition state ("hot tumor") has great significance for enhancing the effect of cellular immunotherapy on solid tumors. Therefore, desialylation combined with CAR-iMac cellular immunotherapy is a promising approach to enhance treatment with cellular immunotherapy and expand the valid indications among solid tumors, which provides inspiration for the development of cellular immunotherapies with glycoimmune checkpoint inhibition for the treatment of human cancer.
Keywords: Siglecs; cellular immunotherapy; desialylation; sialic acid; solid tumors.