Comparison of Prognostic Value of In Vitro Drug Resistance and Bone Marrow Residual Disease on Day 15 of Therapy in Childhood Acute Lymphoblastic Leukemia

The analysis of the prognostic impact of residual disease at day 15 of induction therapy, individual tumor response testing (ITRT) at diagnosis, initial factors and initial therapy response to the risk of relapse in children with precursor B-cell acute lymphoblastic leukemia (ALL). A total of 87 children were tested at diagnosis for ITRT and for persistence of blasts in bone marrow at day 15 (BML15>0.5%) and were followed-up in long-term analysis. The probability of disease-free survival (pDFS) was significantly better for patients with an ITRT profile showing sensitivity to prednisolone, vincristine, daunorubicin, and L-asparaginase. Patients with BML15>0.5% had higher ITRT for prednisolone, daunorubicin, L-asparaginase, and etoposide. Three factors had predictive impact for relapse: BML15>0.5%, ITRT for prednisolone and high combined ITRT profile for prednisolone, vincristine and L-asparaginase (PVA score). Persistence of blasts in bone marrow at day 15, ITRT showing resistance to prednisolone and high PVA score were the strongest and comparable prognostic factors predicting relapse in childhood ALL.