Day 22 of induction therapy is important for minimal residual disease assessment by flow cytometry in childhood acute lymphoblastic leukemia

Minimal residual disease detection by next-generation sequencing of different immunoglobulin gene rearrangements in pediatric B-ALL

While the prognostic role of immunoglobulin heavy chain locus (IGH) rearrangement in minimal residual disease (MRD) in pediatric B-acute lymphoblastic leukemia (B-ALL) has been reported, the contribution of light chain loci (IGK/IGL) remains elusive. This study is to evaluate the prognosis of IGH and IGK/IGL rearrangement-based MRD detected by next-generation sequencing in B-ALL at the end of induction (EOI) and end of consolidation (EOC). IGK/IGL rearrangements identify 5.5% of patients without trackable IGH clones. Concordance rates for IGH and IGK/IGL are 79.9% (cutoff 0.01%) at EOI and 81.0% (cutoff 0.0001%) at EOC, respectively. Patients with NGS-MRD < 0.01% at EOI or <0.0001% at EOC present excellent outcome, with 3-year event-free survival rates higher than 95%. IGH-MRD is prognostic at EOI/EOC, while IGK-MRD at EOI/EOC and IGL-MRD at EOI are not. At EOI, NGS identifies 26.2% of higher risk patients whose MRD < 0.01% by flow cytometry. However, analyzing IGK/IGL along with IGH fails to identify additional higher risk patients both at EOI and at EOC. In conclusion, IGH is crucial for MRD monitoring while IGK and IGL have relatively limited value.

Spectrum and clinical features of gene mutations in Chinese pediatric acute lymphoblastic leukemia

PURPOSE

The 5-year survival rate of children with acute lymphoblastic leukemia (ALL) is 85-90%, with a 10-15% rate of treatment failure. Next-generation sequencing (NGS) identified recurrent mutated genes in ALL that might alter the diagnosis, classification, prognostic stratification, treatment, and response to ALL. Few studies on gene mutations in Chinese pediatric ALL have been identified. Thus, an in-depth understanding of the biological characteristics of these patients is essential. The present study aimed to characterize the spectrum and clinical features of recurrent driver gene mutations in a single-center cohort of Chinese pediatric ALL.

METHODS

We enrolled 219 patients with pediatric ALL in our single center. Targeted sequencing based on NGS was used to detect gene mutations in patients. The correlation was analyzed between gene mutation and clinical features, including patient characteristics, cytogenetics, genetic subtypes, risk stratification and treatment outcomes using χ²-square test or Fisher's exact test for categorical variables.

RESULTS

A total of 381 gene mutations were identified in 66 different genes in 152/219 patients. PIK3R1 mutation was more common in infants (P = 0.021). KRAS and FLT3 mutations were both more enriched in patients with hyperdiploidy (both P < 0.001). NRAS, PTPN11, FLT3, and KMT2D mutations were more common in patients who did not carry the fusion genes (all P < 0.050). PTEN mutation was significantly associated with high-risk ALL patients (P = 0.011), while NOTCH1 mutation was common in middle-risk ALL patients (P = 0.039). Patients with ETV6 or PHF6 mutations were less sensitive to steroid treatment (P = 0.033, P = 0.048, respectively).

CONCLUSION

This study depicted the specific genomic landscape of Chinese pediatric ALL and revealed the relevance between mutational spectrum and clinical features of Chinese pediatric ALL, which highlights the need for molecular classification, risk stratification, and prognosis evaluation.

Treatment of Relapsed and Refractory ALK-Positive Anaplastic Large Cell Lymphoma With ALK-Specific Tyrosine Kinase Inhibitor in Children: A Case Series

Relapsed and refractory ALK-positive anaplastic large cell lymphoma (ALCL) has a poor prognosis. In this report, we present 3 relapsed/refractory pediatric ALCL patients, 1 of these with central nervous system involvement. All 3 patients were treated with ALK inhibitor and achieved complete response. Both crizotinib and alectinib have shown significant activity in pediatric patients with refractory ALK-positive ALCL.

Rare and favorable prognosis of pediatric acute lymphoblastic leukemia with TLS-ERG fusion gene: Case report with long-term follow-up and review of literature

In the study of acute myeloid leukemia (AML), TLS-ERG (also called FUS-ERG or TLS/FUS-ERG) was found to be closely associated with extramedullary disease (EMD), with very poor prognosis. However, the occurrence of TLS-ERG in acute lymphoblastic leukemia (ALL) is very rare. Till date, only 20 cases of ALL with TLS-ERG gene have been reported, of which six are children. Therefore, many clinical aspects of ALL with TLS-ERG gene remain unknown. The aim of this study was to report the clinical features and outcomes of four TLS-ERG-positive pediatric ALL cases. The results showed that all four pediatric patients with this fusion gene achieved an excellent outcome even with a very short-term induction chemotherapy of less than two months. These findings indicated that children with TLS-ERG-positive ALL have very low risk of leukemia, and can be treated and cured with less intensive chemotherapy.

High CD38 expression in childhood T-cell acute lymphoblastic leukemia is not associated with prognosis

BACKGROUND

Prognostic factors are not well exploited in childhood T-cell acute lymphoblastic leukemia (T-ALL).

OBJECTIVE

The aim of this study was to analyze the prognostic role of CD38 as well as minimal residual disease (MRD) and other biological factors in T-ALL.

METHODS

Immunophenotyping of bone marrow (BM) at diagnosis and MRD levels were determined using a standard panel of antibodies by 4-colour flow cytometry. A total of 96 children with T-ALL were enrolled.

RESULTS

The results showed that 97.9% of T-ALL patients were positive for CD38 with a median level of 85.3%. CD38-high group had a worse early treatment response than the CD38-low group. However, CD38 levels were not associated with prognosis, albeit CD38-high group had a worse 5-year event free survival rate (55.1% vs. 66.6%, P> 0.05) and a higher 5-year cumulative incidence of relapse (35.6% vs. 19.8%, P> 0.05). Very high MRD levels (> 10%) were related to the worse survival. Neither flow cytometry based minimal residual disease (MRD) levels nor CD38 expression levels showed significant relation to the hazard of relapse (P> 0.05).

CONCLUSIONS

We conclude that T-ALL has a high level of CD38 expression which is not associated with prognosis. Very high MRD level (> 10%) is related to the worse survival, however, FCM based MRD detection does not convey a significant prognostic value.

Minimal Residual Disease-guided Risk Restratification and Therapy Improves the Survival of Childhood Acute Lymphoblastic Leukemia: Experience From a Tertiary Children's Hospital in China

The minimal residual disease (MRD) has been shown to be very important to evaluate the prognostic significance in childhood acute lymphoblastic leukemia (ALL), but the impact under the current treatment protocol in China has not been fully elucidated. The aim of this study was to investigate the efficacy of MRD-guided risk restratification of ALL. A total of 676 children with ALL were enrolled. In the predictive study group, 476 patients were enrolled with 5-year cumulative incidence of relapse rates of the low-risk (LR), intermediate-risk (IR), and high-risk groups being 11.0%±2.3%, 12.6%±3.3%, and 32.7%±4.9%, respectively. In the intervention study group, 19/200 patients enrolled were reclassified into risk groups according to the MRD levels. The 3-year event-free survival and overall survival were 85.2%±2.9% and 90.6%±2.1%, respectively, which were higher than those of the predictive study group (79.1%±1.9% and 84.7%±1.7%, respectively; P<0.05). The 3-year cumulative incidence of relapse in the LR and IR groups of the intervention study group were 4.2%±3.1% and 6.4%±3.1%, respectively, which were significantly lower than those in the predictive study group (7.2%±1.8% and 11.8%±3.2%, respectively; P<0.05). We conclude that the risk of relapse in the LR and IR groups can be significantly reduced after MRD-guided risk restratification.

ETS-related gene is a novel prognostic factor in childhood acute lymphoblastic leukemia

The ETS-related gene (ERG) has been demonstrated to be associated with overall survival in cytogenetically normal acute myeloid leukemia and acute T cell-lymphoblastic leukemia (T-ALL) in adult patients. However, there are no data available regarding the impact of ERG expression on childhood ALL. In the present study, ERG expression levels were analyzed in bone marrow samples from 119 ALL pediatric patients. ALL patients demonstrated higher ERG expression compared with the controls (P<0.0001). In addition, low ERG expression identified a group of patients with higher white blood cell counts (P=0.011), higher percentages of T-ALL immunophenotype (P=0.027), and higher relapse rates (P=0.009). Survival analyses demonstrated that low ERG expression was associated with inferior relapse-free survival (RFS) in childhood ALL (P=0.036) and was an independent prognostic factor in multivariable analyses for RFS. In conclusion, low ERG expression is associated with poor outcomes and may be used to serve as a molecular prognostic marker to identify patients with a high risk of relapse in childhood ALL.

Minimal residual disease testing in acute leukemia

SUMMARY Predictive/prognostic factors in acute leukemia continue to be sought, in order to refine treatment strategies. Minimal residual disease (MRD) testing has been shown to be a statistically significant factor by multivariate analysis in both acute lymphoblastic leukemia (ALL) and acute myeloid leukemia. Its utility in guiding therapy has been more extensively studied in pediatric ALL, with some protocols having instituted MRD testing into therapeutic algorithms. The clinical impact of MRD testing in ALL and acute myeloid leukemia will be presented, including both molecular and flow cytometric methodologies, with a more focused discussion of the strategy, methodology and interpretation of MRD testing by multiparametric flow cytometry.

Absolute lymphocyte count is associated with minimal residual disease level in childhood B-cell precursor acute lymphoblastic leukemia

The prognostic value of absolute lymphocyte count (ALC) has been a recent matter of debate in childhood acute lymphoblastic leukemia (ALL). In the current study, ALCs at the time of diagnosis (ALC-0), after 7 days of initial therapy (ALC-8) and at interim of the induction therapy (ALC-22) were examined in Chinese children with B-cell precursor (BCP) ALL and correlated with the level of minimal residual disease (MRD) at day 22 of induction therapy. Medical and laboratory records of 140 patients diagnosed with childhood BCP ALL were retrieved and analyzed. ALC-22 is significantly correlated with MRD level at day 22 of therapy and can be a good prognostic factor for childhood BCP-ALL. Furthermore, lymphocyte count at initial diagnosis is correlated with MRD level at day 22 in childhood BCP-ALL with the immnunophenotype of CD19(pos)/CD10(pos)/CD34(pos)/CD45(neg) and role as a new prognostic factor was determined.

Prognostic significance of flow cytometric minimal residual disease assessment after the first induction course in Chinese childhood acute myeloid leukemia

Flow cytometry based minimal residual disease (MRD) was evaluated for outcome prediction in childhood acute myeloid leukemia (AML). The median levels of MRD in relapsed and nonrelapsed patients were different after the first induction (0.64% vs. 0.18%, P=0.030). A cutoff level of ≥ 0.25% after the first course of induction was correlated with a high risk of relapse in both univariate analysis (5-year cumulative incidence of relapse: 66.8% vs. 21.2%, P=0.002) and multivariate analyses (hazard ratio: 3.70, 95% CI, 1.23-11.08, P=0.020). Our results showed that MRD level after the first induction therapy provides important information for risk assessment in childhood AML.