Clinical relevance of FLT3 receptor protein expression in Indian patients with acute leukemia

Aim: FLT3 is a receptor tyrosine kinase that plays an important role in the pathogenesis of leukemia. The present study aimed to evaluate the role of FLT3 protein in patients with acute leukemia. Method: FLT3 protein was quantified by flow cytometry on leukemic blasts using CD135 antibody in 160 patients with acute leukemia. Results: We demonstrated FLT3 protein expression (>20%) in 82% of acute myeloid leukemia (AML), 60% of B‐lineage acute lymphoblastic leukemia (B‐ALL), 23% of T‐lineage acute lymphoblastic leukemia (T‐ALL) and 80% of biphenotypic leukemia. Further, FLT3 expression was seen to be significantly higher in AMLM2, M4, and M5 than in AMLM3. In B‐ALL, FLT3 was found to be higher in pro‐B‐ALL and lower in early B‐ALL. A CD34 expression >20% was associated with FLT3 positive B‐ALL. When correlated with disease status, all patients in the relapsed AML group had FLT3 > 20% at diagnosis. Unlike AML, the relapsed group of B‐ALL showed a lower incidence of FLT3 than the remission group. Conclusion: In summary, our data imply that there is frequent overexpression of the FLT3 protein in AML and B‐ALL patients of Indian origin. In future, the FLT3 protein level may be used to select patients for whom FLT3 inhibitor therapy may be indicated.