MGMT and brain neoplasm: Another hurdle for clinical translation of this approach to brain tumor therapy is the delivery across the BBB.70, 71 Additional experiments to determine the optimal mode of delivery across the BBB with MGMT-expressing brain tumors are currently underway using a vivo-morpholino backbone.18 Successful delivery across the BBB would be necessary to be effective in brain tumors, and we used ‘standard’ rather than vivo-morpholino backbone that has a larger molecular size for our sequences and are less likely to cross the BBB.