MSLN expression in pediatric and adult AML. (A) MSLN transcript expression was detected in a subset of pediatric AML cases (n = 1031) but was absent in NBM (n = 68) and CD34⁺ PB cells (n = 16), as determined by RNA-Seq. (B) MSLN expression in pediatric (TARGET cohort) and adult (TCGA and BEAT AML) AML patients compared with several MSLN⁺ solid tumors in patients from the TCGA cohort. (C) Concordance of MSLN transcript expression, positive vs negative, at diagnostic and relapse time points, according to karyotype (KMT2A-R, CBF, other, and normal karyotype). (D) Percentage of cells above autofluorescence, representing the percentage positivity on blasts, for some archetypal surface antigens in AML that are considered immunotherapeutic targets (CD117, CD33, CD123) and MSLN, showing similar distribution of heterogeneity of expression.