RA and arsenic induce growth inhibition in NPM1 mutated AML cells ex vivo and in vivo. (A) Primary AML cells from 3 different AML patients were treated with arsenic (1 μM), RA (1 μM) or a combination of both for 48 hours. Cell growth (percent of control) was assayed in duplicate wells. (B) Percent of PB and BM blasts and treatment schedule in 3 NPM1–mutated AML patients treated with RA and arsenic as indicated. ND, not done.