Utility of a multiplex reverse transcriptase-polymerase chain reaction assay (HemaVision) in the evaluation of genetic abnormalities in Korean children with acute leukemia: a single institution study

Interdisciplinary Quality Improvement Led by the Molecular Pathology Laboratory Expedites Diagnosis of Acute Promyelocytic Leukemia

OBJECTIVES

Acute promyelocytic leukemia (APL) requires emergent treatment while definitive laboratory results are pending. Following the death of a patient whose diagnosis was delayed, we sought to improve our institution's workflow by using the EPIDEM (Exploration, Promotion, Implementation, Documentation, Evaluation, Modification) quality improvement model.

METHODS

APL is confirmed by identifying translocation t(15;17)(q24;q21) PML-RARA by using either molecular or cytogenetic methods on peripheral blood or bone marrow specimens. We used the EPIDEM model to decrease the turnaround time (TAT) of molecular diagnosis by improving communication and developing reflex testing. We additionally compared 32 APL cases against a control group of 18 suspected APL cases.

RESULTS

Our review of 687 multiplex polymerase chain reaction orders and 33 PML-RARA orders (January 2012 to April 2021) showed an initial TAT decrease from 4.48 days to 2.71 days (P < .0001), which further decreased to 0.64 days (P < .0001) after implementation of the PML-RARA qualitative assay. Compared with patients suspected of having APL, patients with confirmed APL had higher dimerized plasmin fragment D (P = .0145), lower fibrinogen (P ≤ .0001), and lower WBC (P ≤ .0001).

CONCLUSIONS

By using the EPIDEM model, with its emphasis on local context, culture, and resources, improved communication and workflow changes enabled us to reduce the time needed to diagnose APL to 0.64 days and identify potential locally derived screening cutoffs.

High incidence of RAS pathway mutations among sentinel genetic lesions of Korean pediatric BCR-ABL1-like acute lymphoblastic leukemia

INTRODUCTION

Recent advances in genetic analysis have led to the discovery of novel genetic subtypes of precursor B-cell acute lymphoblastic leukemia (B-ALL) with prognostic relevance. In this study, we studied a cohort of pediatric B-ALL patients to retrospectively determine the incidence of patients harboring novel genetic subtypes, as well as their outcome.

METHODS

B-ALL patients (N = 190) diagnosed in a single Korean hospital were included in the study. Patients' medical records were reviewed for data on established genetic abnormalities and outcome. CRLF2 expression was analyzed by quantitative RT-PCR. Anchored multiplex PCR-based enrichment was used to detect fusions and point mutations in 81 ALL-related genes.

RESULTS

Incidence of established recurrent genetic subtypes was as follows: high hyperdiploidy (21.6%), ETV6-RUNX1 (21.6%), BCR-ABL1 (7.9%), KMT2A rearrangement (7.4%) TCF3-PBX1/TCF3-HLF (7.4%), and hypodiploidy (1.1%). Incidence of new genetic subtypes was as follows: BCR-ABL1-like (13.2%), ETV6-RUNX1-like (2.1%), EWSR1-ZNF384 (1.1%), and iAMP21 (1.1%). Median age at diagnosis of BCR-ABL1-like ALL was 6.8 years. According to type of genetic abnormality, BCR-ABL1-like ALL was divided into ABL class (12%), CRLF2 class (8%), JAK-STAT class (12%), and RAS class (68%). The 5-year event-free survival (EFS) of BCR-ABL1-like patients was significantly inferior to non-BCR-ABL1-like low- and standard-risk patients (71.5 ± 9.1% vs 92.5 ± 3.2%, P = .001) and comparable to non-BCR-ABL1-like high (75.2 ± 6.2%) and very high-risk patients (56.8 ± 7.4%). All four ETV6-RUNX1-like patients survived event-free.

CONCLUSION

Analogous to previous studies, incidence of BCR-ABL1-like ALL in our cohort was 13.2% with outcome comparable to high and very high-risk patients. A significantly high number of RAS class mutations was a distinct feature of our BCR-ABL1-like ALL group.

Prognostic Role of Postinduction Minimal Residual Disease and Myeloid Sarcoma Type Extramedullary Involvement in Pediatric RUNX1-RUNX1T1 (+) Acute Myeloid Leukemia

BACKGROUND

Acute myeloid leukemia with the t(8;21)(q22;q22) rearrangement (RUNX1-RUNX1T1 (+) AML) is known to have a favorable prognosis. Our study aimed to determine the most important prognostic variables among an aggregate of clinical, genetic, and treatment response-based factors in pediatric RUNX1-RUNX1T1 (+) AML.

MATERIALS AND METHODS

We analyzed the characteristics and outcome of 40 patients who were diagnosed with and treated for RUNX1-RUNX1T1 (+) AML from April 2008 to December 2016 at our institution.

RESULTS

A<-2.2 log fusion transcript decrement after remission induction, myeloid sarcoma type extramedullary involvement (EMI) at diagnosis, higher initial white blood cell count, and presence of KIT mutation predicted lower event-free survival. Both lower fusion transcript decrement after remission induction and the presence of EMI at diagnosis proved to be significant adverse factors in the multivariate study. The 5-year event-free survival was 70.0±7.2% (28/40); 8 of the 12 relapsed patients survive disease-free, resulting in 5-year overall survival of 89.5±5.0% (36/40).

CONCLUSIONS

Kinetics of response to remission induction chemotherapy, measured in terms of the PCR value for the fusion transcript, and the presence of myeloid sarcoma type EMI at diagnosis may predict the risk of relapse in pediatric RUNX1-RUNX1T1 (+) AML.

Treatment of children with acute lymphoblastic leukemia with risk group based intensification and omission of cranial irradiation: A Korean study of 295 patients

BACKGROUND

Recent studies indicate 70-80% event-free survival (EFS) for pediatric acute lymphoblastic leukemia (ALL). In this study, we report the outcome of 295 children and adolescents treated at our institution, with stratification into four risk groups, and omission of cranial irradiation in all patients.

PROCEDURE

Patients were diagnosed from January 2005 to December 2011 and classified and treated as low, standard, high, and very high risk groups. A delayed intensification phase was given twice for high and very high risk groups. None of the patients received cranial irradiation for central nervous system (CNS) prophylaxis.

RESULTS

The 10-year EFS and overall survival (OS) were 78.5 ± 2.5% and 81.9 ± 2.7%, respectively. EFS according to risk group was as follows: low risk 91.2 ± 3.7%, standard risk 98.1 ± 1.9%, high risk 81.5 ± 4.3%, very high risk 59.4 ± 5.3%. In a multivariate analysis, high hyperdiploidy and infant ALL were significant predictors of EFS. Cumulative incidence of any relapse, isolated CNS relapse, and any CNS relapse were 17.1 ± 2.3%, 1.5 ± 0.7%, and 2.3 ± 0.9%, respectively. Other events included infection-related deaths during remission induction chemotherapy (3), primary refractory disease (2), and treatment-related deaths in first complete remission (8).

CONCLUSIONS

In this single-institution study of Korean pediatric ALL patients, risk group based intensification with omission of cranial irradiation resulted in EFS comparable to previous studies, excellent survival of low- and standard-risk patients, and a low rate of CNS relapse.

Outcome and Prognostic Factors for ETV6/RUNX1 Positive Pediatric Acute Lymphoblastic Leukemia Treated at a Single Institution in Korea

Purpose

ETV6/RUNX1 (+) acute lymphoblastic leukemia (ALL), which is the most common genetic subtype of pediatric ALL, has a favorable prognosis. In this study, we analyzed the outcome of ETV6/RUNX1 (+) ALL patients treated at our institution with the aim of identifying significant prognostic variables.

Materials and Methods

Sixty-three patients were diagnosed with ETV6/RUNX1 (+) ALL from 2005 to 2011. Prognostic variables studied included minimal residual disease (MRD) as detected by ETV6/RUNX1 (+) fusion, and the presence of additional cytogenetic abnormalities.

Results

The 5-year event-free survival was 84.1±4.6%, with 10 patients relapsing at a median of 28.3 months from diagnosis for a 5-year cumulative incidence of relapse of 15.9±4.6%. Multivariate analysis revealed that the presence MRD, as detected by real-time quantitative-polymerase chain reaction or fluorescence in situ hybridization for ETV6/RUNX1 fusion at end of remission induction, and the presence of additional structural abnormalities of 12p (translocations or inversions) negatively affected outcome. Despite treatment such as allogeneic hematopoietic cell transplantation, eight of the 10 relapsed patients died from disease progression for overall survival of 82.5±6.9%.

Conclusion

ETV6/RUNX1 (+) ALL may be heterogeneous in terms of prognosis, and variables such as MRD at end ofremission induction or additional structural abnormalities of 12p could define a subset of patients who are likely to have poor outcome.