Treatment protocol
Patients were treated using modified BFM (Berlin-Frankfurt-Mṻnster) 95
protocol (Supporting information file). Children with ALL were divided
into standard and high-risk (HR) groups. HR children were: age ≥10
years, total leukocyte counts (TLC) ≥50,000/cumm, T acute lymphoblastic
leukemia (T ALL), mixed phenotype acute leukemia (MPAL), liver or spleen
≥5 cm below costal margin, t(9;22)(q31;q34.1) positive (BCR-ABL), other
unfavorable cytogenetic abnormality, hypodiploidy (chromosome number
≤44), central nervous system (CNS) positive disease (blasts in
cerebrospinal fluid at diagnosis or cranial nerve abnormality), or poor
prednisolone response (absolute blast counts ≥1000/cumm on day 8 of
prednisolone). All other children were classified as standard-risk (SR)
children. All HR children except HR due to hepatosplenomegaly received
prophylactic cranial radiation (CRT) of 12 Gy after Phase II B
(reconsolidation). Children with CNS positive disease received 18 Gy
CRT. Maintenance chemotherapy comprised of vincristine (1.5
mg/m2 every 4 weeks), prednisolone (60
mg/m2 for 7 days every 4 weeks), 6-mercaptopurine
(6MP) (50 mg/m2 daily) and methotrexate (20
mg/m2 weekly) in both SR and HR groups. SR group also
received intrathecal (IT) methotrexate every 8 weeks during maintenance
chemotherapy.