QUESTIONS AND OBJECTIVES OF ALL-MB 2015 STUDY 1. Will the new risk group stratification (especially of T-ALL) to improve overall and event-free survival? 2. Will the new protocol is effective and feasible in patients older than 15 years, and especially in young adults? 3. Whether the intermittent dexamethasone administration in induction will result in a decrease in toxicity and mortality without loss of efficacy? 4. Whether the methylprednisolone administration as basic glucocorticoids during induction, consolidation and maintenance therapy will lead to decrease of severe infections and early mortality rate, improve survival and therapy compliance in adolescents and young adults with B-precursor ALL? 5. Whether the administration of Bortezomib in patients with B-precursor ALL with initial WBC≥100,000/µl will improve treatment outcome? 6. Whether the administration of Idarubicin instead Daunorubicin in low-risk T-ALL patients and two-phase induction in intermediate-risk T-ALL patients will reduce relapse rate and improve survival?