CD19 and acute leukemia: Of note, such a comprehensive MFC-MRD monitoring may allow to disclose some specific phenotype shifts that could offer the chance to exploit novel target treatments developed for other malignancies (as reported for the clinical case of a CD19-positive AML relapse, successfully treated with DLI infusions in combination with anti-CD19 blinatumomab [5], also in keeping with the use of such bispecific T-cell engager (BiTE) in patients with mixed phenotype acute leukemias [6]).