Individual Tumor Response Testing in Multiple Relapsed Acute Myeloid Leukemia in Children

Aim: The analysis of the individualized tumor response testing (ITRT) at first and subsequent relapse in children with acute myeloid leukemia (AML). Patients and Methods: A total of 76 pediatric AML samples underwent ITRT for up to 21 drugs. Results: No significant differences between ITRT at first and subsequent relapse were found, and no drug was found, for which significantly higher resistance of myeloblasts was observed at subsequent relapse, when compared to first relapse of AML. For most tested drugs, patients with relapse had higher IRTR than those with de novo AML. The median relative resistance value between patients with relapse and those with de novo diagnosis for all 21 drugs tested was 1.6. Samples of relapsed AML samples were significantly more resistant to: Idarubicin (1.8-fold), etoposide (5.9-fold), cytarabine (1.7-fold), fludarabine (3.7-fold) and busulfan (4.3-fold). Conclusion: ITRT in relapsed AML is higher in comparison to that at initial diagnosis, while no differences in ITRT between first and subsequent relapse of AML were found.