FLT3 and acute lymphoblastic leukemia: MRX2843, a dual Mer/Flt3 (fms-like tyrosine kinase 3) inhibitor (Mer IC50 = 1.2 nM), showed improved CNS penetration (brain/plasma ration = 0.4) [11] and is currently in phase II trails for relapsed/refractory acute lymphoblastic leukemia (NCT04872478) [14].