SLFN12 and neoplasm: To determine whether BAY 2666605-treated animals retained any SLFN12- and PDE3A-expressing GB1 cells in their brains at the time of euthanasia, we harvested intracranial tumors from 3 control animals and the right cerebral hemisphere from 3 animals treated with BAY 2666605, which is where tumor implantations were previously performed.