Patient 1 was diagnosed at 8 years of age with a left tentorial-based CNS sarcoma after a 2-week history of nausea, lethargy, and diplopia. Clinical workup confirmed that the tumor was primary to the brain...The POG molecular tumor board suggested targeting either JAK (with ruxolitinib) or ALK (with crizotinib). A decision was made to use ruxolitinib given (1) the over-expression of ATF1 target genes, (2) the over-expression of JAK1, and (3) the available pediatric dosing information....The family requested that ruxolitinib be restarted for quality of life, and the patient again showed dramatic improvement in clinical status and an unexpected prolonged period of stable disease until dose reduction because of myelosuppression was required.