Immunophenotyping of blood and bone marrow cells as a way to search for differentiation syndrome risk factors in acute promyelocytic leukemia

Background. Differentiation syndrome (DS) is a potentially fatal complication of therapy for acute promyelocytic leukemia (APL) with an incidence of up to 48 %. To date, no reliable DS risk factors have been found, with the exception of leukocytosis at the APL onset.Aim. To determine the risk factors associated with DS in patients with APL during induction therapy with arsenic trioxide (ATO) and tretinoin (ATRA).Materials and methods. The study included 39 patients with APL, 29 (74.4 %) of them were classified as low-risk according to ELN (European Leukemia Net), 10 (25.6 %) were classified as high-risk. At the disease onset, cytological and molecular (chimeric transcript PML::RARα, FLT3-ITD mutation) bone marrow studies were performed, the expression of 28 differentiation antigens by blood and bone marrow blast cells was determined (markers of early precursors, myeloid and lymphoid differentiation, cell adhesion molecules, chemokine receptors, integrins, selectin), body mass index (BMI) and the leukocytes number dynamics during induction course were assessed. All patients received ATRA and ATO therapy. Patients from the high-risk group at the onset received 1–3 injections of idarubicin (12 mg/m2) and dexamethasone (8–10 mg/m2 2 times a day) to prevent DS until leukocytosis reduced. In cases of DS, dexamethasone was prescribed at a dose of 10 mg/m2 2 times a day; in cases of severe DS, the induction course was interrupted.Results. Of the 39 patients, 12 (30.8 %) were diagnosed with DS: 20 % of high-risk patients (2/10) and 34.5 % of low-risk patients (10/29). There was no statistically significant association of leukocytosis more than 10 × 109 /L at onset, microgranular morphology of blast cells, bcr3-variant PML::RARα, FLT3-ITD mutation with DS. In multivariate analysis, the probability of DS was associated with BMI ≥30 kg/m2 and mean fluorescence intensity of CD38 antigen by blast cells, regardless of risk group. based on the results of the ROC-analysis, the threshold value of mean CD38 fluorescence intensity was set at 25,000 cu, if exceeded, DS is highly likely to develop.Conclusion. the high incidence of DS among low-risk patients is probably due to the lack of prophylactic glucocorticosteroids administration for the development of leukocytosis during ATRA and ATO therapy. BMI ≥30 kg/m2 and mean CD38 fluorescence intensity more than 25,000 cu were identified as statistically significant DS risk factors.