CMI CLL showed high FLT3 receptor expression and were preferentially sensitive to FLT3 inhibition. (A) Left, FLT3 gene expression assessed by RT-qPCR. Data represent mean ± SEM for analysis of PBMCs of patients with CLL from both group (n = 5). P values were calculated using Welch t test, and P < .05 indicates statistically significance. Right, surface expression of FLT3 was determined by flow cytometry analysis. PBMCs from each CLL group (n = 5) was stained for FLT3. P values were calculated using Welch t test, P < .05 indicates statistical significance. (B) Cell viability of primary CLL samples (n = 5, each group) after 72 hours of FLT3 inhibitors treatment. CLL PBMCs were cultured in BM and treated with either Gilteritinib or Quizartinib for 72 hours. Cell viability was measured using Cell Titer-Glo. Percent Cell viability is calculated relative to untreated (100%). P value determined by 2-tailed t test.