Some of the diagnostic, prognostic, and predictive biomarkers are currently used in clinical practice of personalized and targeted oncotherapy, such as: tyrosine kinase inhibitors, e.g., Gleevec® (imatinib; Novartis) in ALL patients with BCR-ABL1 gene rearrangements; FLT3 inhibitor Hydrate® (CEP-701, lestaurtinib; Cephalon Inc.)in ALL patients with MLL rearrangements; and purine nucleoside phosphorylase inhibitor Mundesine® (forodesine; Mundipharma AG) in pediatric T-ALL with purine nucleoside phosphorylase mutation (167, 168). The gene discussed is FLT3; the disease is acute lymphoblastic leukemia.