Low absolute neutrophil count during induction therapy is an adverse prognostic factor in childhood acute lymphoblastic leukaemia

Variation in normal blood cells during chemotherapy has not been recognised as a risk factor guiding chemotherapy in childhood acute lymphoblastic leukaemia (ALL). This study aims to explore whether variations in normal haematopoiesis determine prognosis as well as to improve risk-stratified treatment in childhood ALL. A retrospective study of 279 cases of ALL treated with the CCCG-ALL-2015 regimen in the Division of Pediatric Blood Diseases Center, Institute of Hematology & Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, from May 2015 to January 2017 was performed to analyse the prognostic impact of blood cell levels on day 19 of induction therapy by Kaplan-Meier method. Patients with childhood ALL with absolute neutrophil count (ANC) ≤ 90 cells/μl, absolute monocyte count (AMC) ≤ 10 cells/μl or absolute lymphocyte count (ALC) ≤ 1000 cells/μl on day 19 of induction therapy had a lower event-free survival (EFS) rate than those with higher values (all P < 0.05). Multivariate analysis confirmed that ANC ≤ 90 cells/μl and ALC ≤ 1000 cells/μl were independent adverse prognostic factors (HR = 1.981 and 2.162, respectively, both P < 0.05). Among patients with minimal residual disease (MRD) < 1% on day 19 of induction therapy, those with ANC ≤ 90 cells/μl had lower EFS than those with ANC > 90 cells/μl (70.8 ± 6.1% vs 86.4 ± 3.1%, P = 0.001). In the subgroup with the BCR/ABL1 fusion gene, patients with ANC ≤ 90 cells/μl on day 19 of induction therapy also had lower EFS than those with ANC > 90 cells/μl (34.4 ± 25.2% vs 25.0 ± 21.7%, P = 0.041). ANC and ALC during induction therapy are independent prognostic factors for childhood ALL. ANC contributes to guiding the prognosis of patients with low-level MRD or the BCR/ABL1 fusion gene.