Serum macrophage inhibitory cytokine-1 levels, MIC-1, a secreted biomarker of p53 activation has been used as a pharmacodynamic marker of treatment in clinical trials of AML patients receiving MDM2 inhibitors.(30–32) MIC-1 levels were evaluable in 8 patients at the 21mg dose level. The gene discussed is TP53; the disease is acute myeloid leukemia.