Though there is great complexity, including functional divergence, of the many pathways and ligands involved in the various CD155 signaling interactions, clinical trials targeting CD155 within GBM have already proven efficacious, with intratumoral delivery of a recombinant nonpathogenic polio-rhinovirus chimera (PVSRIPO) yielding a 3-year survival rate of 21% as compared to historical 3-year survival rates of 4% [13]. Here, PVR is linked to glioblastoma.