NOTCH1 and acute lymphoblastic leukemia: OMP-52M51, a novel mAb targeting NRR, not only delays engraftment of T-ALL cells in xenografts derived from poor responders or relapsed patients but also impairs the functional activity of T-LICs; more importantly, OMP-52M51 enhances the in vivo effects of dexamethasone, highlighting the therapeutic potential of anti-NOTCH1 mAbs in combination with steroids [145].