Acute lymphoblastic leukemia (ALL), the most common childhood cancer, is a highly curable disease, with approximately 85% of patients being long-term survivors when treated with current chemotherapy regimens.1 Risk-adapted, intensified chemotherapy regimens have greatly improved the outcome for children, adolescents, and young adults with newly diagnosed B-cell ALL (B-ALL), which comprises approximately 20% of patients with ALL, and can be safely delivered with proper supportive care measures. Intensification of chemotherapy as salvage therapy, frequently adopting the same agents used during initial therapy, has also been successful at inducing sustained remissions for patients with late relapses. However, this approach has been largely unsuccessful for high-risk patients who experience relapse within 3 years from diagnosis because survival outcomes for these patients remain poor.2,3 Additionally, mortality associated with toxicity related to therapy contributes significantly to the poor survival.