Practical Considerations for Using RNA Sequencing in Management of B-Lymphoblastic Leukemia: Malaysia-Singapore Acute Lymphoblastic Leukemia 2020 Implementation Strategy.

Despite the immense genetic heterogeneity of B-lymphoblastic leukemia [or precursor B-cell acute lymphoblastic leukemia (B-ALL)], RNA sequencing (RNA-Seq) could comprehensively interrogate its genetic drivers, assigning a specific molecular subtype in >90% of patients. However, study groups have only started to use RNA-Seq. For broader clinical use, technical, quality control, and appropriate performance validation are needed. We describe the development and validation of an RNA-Seq workflow for subtype classification, TPMT/NUDT15/TP53 variant discovery, and immunoglobulin heavy chain (IGH) disease clone identification for Malaysia-Singapore acute lymphoblastic leukemia (ALL) 2020. We validated this workflow in 377 patients in our preceding Malaysia-Singapore ALL 2003/Malaysia-Singapore ALL 2010 studies and proposed the quality control measures for RNA quality, library size, sequencing, and data analysis using the International Organization for Standardization 15189 quality and competence standard for medical laboratories. Compared with conventional methods, we achieved >95% accuracy in oncogene fusion identification, digital karyotyping, and TPMT and NUDT15 variant discovery. We found seven pathogenic TP53 mutations, confirmed with Sanger sequencing, which conferred a poorer outcome. Applying this workflow prospectively to the first 21 patients in Malaysia-Singapore ALL 2020, we identified the genetic drivers and IGH disease clones in >90% of patients with concordant TPMT, NUDT15, and TP53 variants using PCR-based methods. The median turnaround time was 12 days, which was clinically actionable. In conclusion, RNA-Seq workflow could be used clinically in management of B-cell ALL patients.

Excellent Survival Outcomes of Pediatric Patients With Acute Myeloid Leukemia Treated With the MASPORE 2006 Protocol.

PURPOSE: To determine the prognostic factors in pediatric patients with acute myeloid leukemia (AML) and to assess whether their outcomes have improved over time. PATIENTS AND METHODS: Sixty-two patients with AML excluding acute promyelocytic leukemia were retrospectively analyzed. Patients in the earlier cohort (n = 36) were treated on the Medical Research Council (MRC) AML12 protocol, whereas those in the recent cohort (n = 26) were treated on the Malaysia-Singapore AML protocol (MASPORE 2006), which differed in terms of risk group stratification, cumulative anthracycline dose, and timing of hematopoietic stem-cell transplantation for high-risk patients. RESULTS: Significant improvements in 10-year overall survival and event-free survival were observed in patients treated with the recent MASPORE 2006 protocol compared to the earlier MRC AML12 protocol (overall survival: 88.0% ± 6.5% vs 50.1% ± 8.6%, P = .002; event-free survival: 72.1% ± 9.0 vs 50.1% ± 8.6%, P = .045). In univariate analysis, patients in the recent cohort had significantly lower intensive care unit admission rate (11.5% vs 47.2%, P = .005) and numerically lower relapse rate (26.9% vs 50.0%, P = .068) compared to the earlier cohort. Multivariate analysis showed that treatment protocol was the only independent predictive factor for overall survival (hazard ratio = 0.21; 95% confidence interval, 0.06-0.73, P = .014). CONCLUSION: Outcomes of pediatric AML patients have improved over time. The more recent MASPORE 2006 protocol led to significant improvement in long-term survival rates and reduction in intensive care unit admission rate.

Oncorequisite role of an aldehyde dehydrogenase in the pathogenesis of T-cell acute lymphoblastic leukemia.

Aldehyde dehydrogenases (ALDHs) are overexpressed in various types of cancers. One of the ALDH family genes, ALDH1A2, is aberrantly expressed in more than 50% of T-cell acute lymphoblastic leukemia (T-ALL) cases. However, its molecular function and role in T-ALL pathogenesis are largely unknown. ChIP-seq and RNA-seq analyses showed that the oncogenic transcription factor TAL1 and its regulatory partners bind to the intronic regulatory element of the ALDH1A2 gene, directly inducing a T-ALL-specific isoform with enzymatic activity. ALDH1A2 was preferentially expressed in the TAL1-positive T-ALL subgroup. In T-ALL cell lines, depletion of ALDH1A2 inhibited cell viability and induced apoptosis. Interestingly, gene expression and metabolomic profiling revealed that ALDH1A2 supported glycolysis and the TCA cycle, accompanied by NADH production, by affecting multiple metabolic enzymes to promote ATP production. Depletion of ALDH1A2 increased the levels of reactive oxygen species (ROS), while ROS levels were reduced by ALDH1A2 overexpression both in vitro and in vivo. Overexpression of ALDH1A2 accelerated tumor onset and increased tumor penetrance in a zebrafish T-ALL model. Taken together, our results indicate that ALDH1A2 protects against intracellular stress and promotes T-ALL cell metabolism and survival. ALDH1A2 overexpression enables leukemic clones to sustain a hyper-proliferative state driven by oncogenes.