FLT3 and pSTAT5 expression in response to gilteritinib treatment. Using spectral flow, a sensitive (A) and an unresponsive (B) primary sample were first gated for myeloblasts using AML surface markers (CD45 dim and CD33⁺) and then FLT3/CD135 and pSTAT5 expression. Pre-treatment samples are indicated in blue, and post-treatment samples are indicated with red. MFI, mean fluorescent intensity.