Minimal Coexpression of CD34+/CD56+ in Acute Promyelocytic Leukemia Is Associated With Relapse

Cytoreductive chemotherapy in induction therapy plays a key role in the prognosis of patients with low-risk acute promyelocytic leukaemia

In order to explore the risk factors of relapse and potential optimized therapeutic regimen of low-risk acute promyelocytic leukaemia (APL), here we retrospectively analysed 282 patients who were diagnosed between February 2014 and September 2021. The median follow-up was 59 (9-102) months. The 5-year overall survival and cumulative relapse incidence were 97.9% and 5.9%, respectively. In terms of different cytoreductive therapies, 86 patients were administered with hydroxycarbamide (30.5%), 113 with anthracyclines or cytarabine (40.1%), 31 with etoposide (11.0%) and 52 with no cytoreductive therapy (18.4%) during the induction therapy. The hydroxycarbamide treatment group did not decrease the relapse rate compared to the no cytoreduction group (11.4% vs. 5.9%, p = 0.289). Compared with the hydroxycarbamide group, the anthracyclines/cytarabine treatment group showed improved 5-year RFS (88.145% vs. 98.113%, p = 0.008). Multivariate Cox regression analysis revealed that myeloblasts in bone marrow at diagnosis, and PML-RARA transcript level of 6.5% or more after induction therapy were associated with a subsequent risk of relapse. The only factor positively reducing the relapse rate was anthracyclines/cytarabine cytoreductive treatment. In conclusion, cytoreductive chemotherapy in induction therapy plays a potential key role in the prognosis of low-risk APL.

PML-RARA transcript levels at the end of induction therapy are associated with prognosis in non-high-risk acute promyelocytic leukaemia with all-trans retinoic acid plus arsenic in front-line therapy: long-term follow-up of a single-centre cohort study

Despite the high cure probability for acute promyelocytic leukaemia (APL), a minority of patients will relapse and the risk factors for relapse are unclear. We retrospectively analysed 212 patients who were diagnosed with non-high-risk APL and received all-trans retinoic acid (ATRA) plus arsenic as front-line therapy at Peking University Institute of Hematology from February 2014 to December 2018. A total of 176 patients (83%) received oral arsenic (realgar-indigo naturalis formula) plus ATRA, 36 patients (17%) received arsenic trioxide plus ATRA and 203 patients were evaluable for relapse. After a median (range) follow-up of 53·6 (24·3-85·4) months, two patients had molecular relapse and eight had haematological relapse. A promyelocytic leukaemia/retinoic acid receptor alpha (PML-RARA) transcript level of ≥6·5% at the end of induction therapy was associated with relapse (P = 0·031). The 5-year cumulative incidence of relapse, event-free survival and overall survival were 5·5%, 92·3% and 96·3% respectively. In conclusion, the present long-term follow-up study further confirmed the high cure probability of ATRA plus oral arsenic as front-line therapy for non-high-risk APL and showed that the PML-RARA transcript level at the end of induction therapy was associated with relapse.

A narrative review of central nervous system involvement in acute leukemias

Acute leukemias (both myeloid and lymphoblastic) are a group of diseases for which each year more successful therapies are implemented. However, in a subset of cases the overall survival (OS) is still exceptionally low due to the infiltration of leukemic cells in the central nervous system (CNS) and the subsequent formation of brain tumors. The CNS involvement is more common in acute lymphocytic leukemia (ALL), than in adult acute myeloid leukemia (AML), although the rates for the second case might be underestimated. The main reasons for CNS invasion are related to the expression of specific adhesion molecules (VLA-4, ICAM-1, VCAM, L-selectin, PECAM-1, CD18, LFA-1, CD58, CD44, CXCL12) by a subpopulation of leukemic cells, called “sticky cells” which have the ability to interact and adhere to endothelial cells. Moreover, the microenvironment becomes hypoxic and together with secretion of VEGF-A by ALL or AML cells the permeability of vasculature in the bone marrow increases, coupled with the disruption of blood brain barrier. There is a single subpopulation of leukemia cells, called leukemia stem cells (LSCs) that is able to resist in the new microenvironment due to its high adaptability. The LCSs enter into the arachnoid, migrate, and intensively proliferate in cerebrospinal fluid (CSF) and consequently infiltrate perivascular spaces and brain parenchyma. Moreover, the CNS is an immune privileged site that also protects leukemic cells from chemotherapy. CD56/NCAM is the most important surface molecule often overexpressed by leukemic stem cells that offers them the ability to infiltrate in the CNS. Although asymptomatic or with unspecific symptoms, CNS leukemia should be assessed in both AML/ALL patients, through a combination of flow cytometry and cytological analysis of CSF. Intrathecal therapy (ITT) is a preventive measure for CNS involvement in AML and ALL, still much research is needed in finding the appropriate target that would dramatically lower CNS involvement in acute leukemia.

[Analysis of immunophenotypes and expressions of non-myeloid antigens in acute myeloid leukemia]

OBJECTIVE

To investigate the characteristics of immunophenotypes and expressions of non-myeloid differentiation antigens in acute myeloid leukemia (AML) and their value in diagnosis and prognostic evaluation of AML.

METHODS

We examined the immunophenotypes of 109 patients with AML using BD FACSCalibur flow cytometry and analyzed the association of the immunophenotypes and expressions of non-myeloid differentiation antigens with the prognosis and complete remission (CR) rate of the patients.

RESULTS

Immunophenotype analysis showed that the positivity rates of the myeloid differentiation antigens of AML cells decreased in the order of CD13, CD117, CD33, MPO and CD15; the positivity rates of CD117, CD13, CD33 and MPO did not differ significantly (P > 0.05) and were all significantly higher than that of CD15 (P < 0.05). The positivity rates of AML cell non-lineage antigens CD34, CD38, HLA-DR, and CD123 did not differ significantly (P > 0.05). The positivity rates of non-myeloid differentiation antigens decreased in the order of CD9, CD200, CD56 and CD7 in AML cells and were all significantly higher than those of CD25, CD19, CD2, CD10, CD4, CyCD79a and CyCD3 (P < 0.05). Among the 109 AML patients, the CR rates of patients positive for CD7, CD34, CD56 and CD25 were significantly lower than those negative for these antigens (P < 0.05); the CR rates were significantly higher in patients positive for MPO and CD19 than in the negative patients (P < 0.05). Among the 15 AML-M2b patients with AML1-ETO positivity, the CR rate following a single treatment course was significantly lower in patients positive for CD56 than in CD56-negative patients, and CD56-positive patients also had a significantly higher relapse rate within 1 year (P < 0.05).

CONCLUSIONS

Immunophenotyping and analysis of non-myeloid differentiation antigens can be of great clinical significance for the diagnosis and prognostic evaluation of AML, and serve also as one of the important bases for the diagnosis and treatment of AML.