For international readers｜Evidence: Single-center clinical study published 2019 in Journal of China Pediatric Blood and Cancer by Wu Nanhai, Sun Yuan, Wu Min-yuan team
Retrospective clinical study of 32 domestic infant-leukemia patients (age at diagnosis ≤ 1 year old)
Infant leukemia is defined as leukemia diagnosed within the first year of life. It is internationally recognized for high treatment complexity, substantial risk of infection related mortality and high relapse risk.
Our center treated infant leukemia with the CCLG-ALL2008 protocol for infant acute lymphoblastic leukemia (ALL) and the BCH-AML05 protocol for infant acute myeloid leukemia (AML). The induction complete-remission rate reached 100 %. Satisfactory outcomes were achieved in controlling treatment-related mortality and relapse rate, with therapeutic effects comparable to, and in some aspects better than, data from multiple well-known international collaborative groups.
Induction complete-remission rate: 100 %. All patients achieved complete remission after induction therapy. Minimal residual disease (MRD) turned negative for all patients by Week 12, which represented a key factor for low relapse rates.
Survival outcomes: 2-year overall survival (OS): 72 % ±13 %; 2-year event-free survival (EFS): 67 % ±13 %. The 2-year cumulative relapse rate was merely 17 % ±11 %, markedly lower than the internationally-reported relapse rate of 50-60 %.
Prognostic advantage stratified by MLL-gene rearrangement: For patients without MLL-gene rearrangement, both 2-year OS and EFS reached 100 %, with zero relapse and zero treatment-related death. Cure was achieved with only moderate-intensity chemotherapy without excessive-intensified treatment.
Low treatment-related mortality: Treatment-related mortality (TRM) was only 10 %, significantly lower than the internationally-reported TRM of approximately 20 %.
Induction complete-remission rate: 100 %. All patients achieved complete remission after the first course of chemotherapy.
Survival outcomes: 2-year OS: 83 % ±11 %; 2-year EFS: 61 % ±16 %. Outcomes were comparable to those for leukemia in older children and matched results from top-tier international collaborative groups.
Controllable treatment-related mortality: TRM stood at only 8 %. Dose optimization (25 % reduction in total dosage) avoided infant intolerance to cytarabine toxicity and reduced the risk of fatal toxicities.
For the ALL protocol: High-dose methotrexate was retained for consolidation therapy, while highly-toxic high-dose cytarabine was replaced with low-dose cytarabine. This strategy balanced therapeutic efficacy, reduced fatal infection and organ injury, and lowered treatment-related mortality.
For the AML protocol: Dosing was calculated based on body surface area with an overall 25 % dose reduction to accommodate the fragile organ tolerance of infants and decrease mortality risk from chemotherapy-related toxicities.
During the induction phase, artificial feeding was adopted to facilitate strict disinfection of feeding utensils. Laminar-flow isolation was implemented as early as possible during neutropenia. Emphasis was placed on preventing and managing severe infection and severe diarrhea, which effectively reduced the risk of early treatment-related death.
Minimal residual disease was dynamically monitored at Day 33 and Week 12. Risk stratification was adjusted in a timely manner for early relapse-risk prediction and guidance of subsequent therapeutic decisions (including hematopoietic stem-cell transplantation).
The 4- to 5-year EFS for infant ALL reported by large-scale collaborative groups across Europe, America and Japan mostly ranged from 42 % to 51 %. In this study, the 2-year EFS for infant ALL reached 67 %, and 100 % for the MLL-rearrangement-negative subgroup. Outcomes for infant AML were on par with international studies such as the European BFM and UK MRC trials, with several survival indicators demonstrating superior performance.
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