Impacto da detecção de blastos leucêmicos durante o protocolo de tratamento dos pacientes pediátricos com leucemia linfoblástica aguda de células b: implicações clínicas elaboratoriais

Abstract

Measurable residual disease (MRD) is the most important independent predictor of relapse risk and long-term survival in children with B-cell acute lymphoblastic leukemia (B-ALL), defined as the detection and/or quantification of residual leukemic blasts beyond the sensitivity level of cytomorphology, i.e., by more sensitive methodologies such as flow cytometry or molecular methods. Negative MRD is considered, to a variable extent and according to the technique adopted, as <0.01 to 0.1% of leukemic blasts in the bone marrow (BM). Based on this result, it is possible to optimize chemotherapy, minimizing toxicity and reducing the risk of relapse. Thus, our study described the clinical and laboratory implications after the identification of leukemic blasts during the treatment protocol of pediatric patients with B-ALL. A longitudinal, prospective, analytical study was conducted to evaluate bone marrow (BM) and peripheral blood (PB) samples from pediatric patients undergoing remission induction therapy for B-ALL at the Fundação Hospitalar de Hematologia e Hemoterapia do Amazonas (HEMOAM) for evaluation of MRD by flow cytometry (FC). The protocols and guidelines of the EuroFlow Consortium were used, with the acquisition of samples on the FACSCanto II cytometer of the HEMOAM Foundation and the analysis of immunophenotyping data with the Kaluza software (v1.2). In parallel, sociodemographic and clinical-laboratory data were collected

from the iDoctor System, physical records of patients and the SofLab system. Twenty- five patients diagnosed with B-ALL at an average age of 6 years, predominantly female

(68%), were included in the study. The individuals were evaluated and started treatment with the BFM-2009 protocol, being classified into high-risk (40%), intermediate-risk (32%), and low-risk (28%) groups. When comparing the techniques adopted by the routine with flow cytometry analysis using the protocol adapted from the EuroFlow Consortium, it was noted that there was significantly greater acquisition and evaluation of cells by the method described in our study. When comparing the detection of LCs, we observed that our protocol (adapted from the EuroFlow Consortium) was significantly better in detecting blasts at times D15, D35, and D84. Although no significant differences were observed at D8, it was noted that the FC was relatively better than the automated count. In conclusion, we can see that our study indicated better results regarding the early detection of leukemic blasts and the evaluation of MRD during chemotherapy treatment, with a positive impact on the patients' prognosis.