The MAOI and nonselective LSD1 inhibitor tranylcypromine (TCP) was recently evaluated in combination with ATRA for the treatment of R/R AML and MDS, with an acceptable safety profile and evidence of clinical benefit including an ORR of 23.5%, where response was associated with a quiescent (hypoproliferative) CD34+ phenotype (105). Here, KDM1A is linked to acute myeloid leukemia.