Prognostic gene alterations and clonal changes in childhood B-ALL

Status of IKZF1 Deletions in Diagnose and Relapsed Pediatric B-ALL Patients

IKZF1 deletions (ΔIKZF1) are common in precursor B-cell acute lymphoblastic leukemia (B-ALL) and are assumed to have a prognostic impact. We aimed to determine the prognostic implications of ΔIKZF1 and CRLF2 overexpression in pediatric B-ALL. Furthermore, we sought to compare the multiplex polymerase chain reaction (PCR) assay with standard multiplex ligand-dependent probe amplification (MLPA) methods to ascertain IKZF1 status in a clinical context. Seventy-nine diagnoses and 43 relapse B-ALL samples were evaluated for deletions of IKZF1 Δ2-7, Δ4-7, and Δ4-8 by conventional PCR and then sequenced by targeted sequencing. Subsequently, MLPA analysis was performed for ΔIKZF1 detection, and CRLF2 expression was evaluated in 42 diagnose time B-ALL patients by QRT-PCR. ΔIKZF1 was detected in 10 out of 79 diagnose samples (12.66%) and eight of the 43 first relapsed materials (18.60%). Our results revealed no association between survival outcomes with ΔIKZF1 or CRLF2 overexpression status in pediatric B-ALL patients. However, we found ΔIKZF1 was more frequent among relapsed samples, and the deletions showed consistency between diagnose-first/second relapse pairs of samples. These results suggest that ΔIKZF1 may contribute to the development of treatment failure in B-ALL. Furthermore, we demonstrated methodological adjustments in conventional PCR and MLPA for selected alterations in ΔIKZF1.

Prognostic significance of copy number variation in B-cell acute lymphoblastic leukemia

Copy number variations (CNVs) are widespread in both pediatric and adult cases of B-cell acute lymphoblastic leukemia (B-ALL); however, their clinical significance remains unclear. This review primarily discusses the most prevalent CNVs in B-ALL to elucidate their clinical value and further personalized management of this population. The discovery of the molecular mechanism of gene deletion and the development of targeted drugs will further enhance the clinical prognosis of B-ALL.

Copy Number Alterations are Associated with the Risk of Very Early Relapse in Pediatric B-lineage Acute Lymphoblastic Leukemia: A Nested Case-control MIGICCL Study

BACKGROUND

Refining risk stratification to avoid very early relapses (VER) in Mexican patients with B-lineage acute lymphoblastic leukemia (B-ALL) could lead to better survival rates in our population.

AIM OF THE STUDY

The purpose of this study was to investigate the association between the United Kingdom ALL (UKALL)-CNA classifier and VER risk in Mexican patients with childhood B-ALL.

METHODS

A nested case-control study of 25 cases with VER and 38 frequency-matched controls without relapse was conducted within the MIGICCL study cohort. They were grouped into the categories of the UKALL-CNA risk classifier (good [reference], intermediate and poor), according to the results obtained by multiplex ligation dependent probe amplification. Overall and disease-free survival (DFS) were estimated using the Kaplan-Meier method. Univariate and multivariate Cox proportional hazards analyses were conducted.

RESULTS

The CDKN2A/B genes were most frequently deleted in the group with relapse. According to UKALL-CNA classifier, 33 (52.4%) patients were classified as good, 21 (33.3%) intermediate and 9 (14.3%) poor-risk B-ALL. The intermediate and poor risk groups were associated with an increased risk of VER (HR = 4.94, 95% CI = 1.87-13.07 and HR = 7.42, 95% CI = 2.37-23.26, respectively) in comparison to the good-risk patients. After adjusting by NCI risk classification and chemotherapy scheme in a multivariate model, the risks remained significant.

CONCLUSIONS

Our data support the clinical utility of profiling CNAs to potentially refine current risk stratification strategies of patients with B-ALL.