A barrier-crossing and immune checkpoint-blocking antibody fusion protein for enhanced glioma-targeted immunotherapy

With low five-year survival estimates, poor prognosis, and high recurrence probabilities, glioma is considered one of the most intractable malignant tumors. Despite the discovery of lymphatic vascular system and immune system in the central nervous system (CNS), immune checkpoint blockade therapeutics, such as programmed death ligand 1 (PDL1, also called B7H1 or CD274) antibodies, are prevented from the CNS and glioma sites due to the existence of biological barriers including the blood-brain barrier (BBB) and blood-brain tumor barrier (BBTB). Herein, we constructed a BBB/BBTB-crossing recombinant antibody by fusing the PDL1 antibody (αPDL1) and the targeting moiety RAP22 peptide (RAP22) through a matrix metalloproteinase 2 (MMP2)-responsive cleavable linker, abbreviated as αPDL1-mRAP22. Not only was αPDL1-mRAP22 able to block PD1/PDL1 pathway, reduce T cell apoptosis, enhance T cell killing ability towards glioma cells in vitro , but also it showed higher accumulation in the glioma site, prolonged survival time, and potent immune responses as well as synergistic effects with temozolomide (TMZ) in vivo , offering a novel strategy for glioma immunotherapy.