Based on the preclinical data suggesting the synergistic anticancer effect of the combination of dexamethasone with the MEK 1/2 inhibitor, selumetinib [113], the Cancer Research UK Clinical Trials Unit (University of Birmingham) has sponsored an international, parallel-group, dose-finding with expansion, phase I/II trial (NCT03705507) to assess the selumetinib/dexamethasone combination in adult and pediatric patients with R/R RAS pathway-mutant ALL [114]. Here, MAP2K1 is linked to acute lymphoblastic leukemia.