We speculated that enhanced effects of regorafenib may also occur with other DNA damaging agents and therefore evaluated its combination with the topoisomerase I inhibitor irinotecan, used in salvage strategies in brain tumors [48–50], against the pediatric IGRM57 medulloblastoma model, which also exhibits a PDGFRA amplification (Fig 4B). The gene discussed is PDGFRA; the disease is medulloblastoma.