The significance of peripheral blood minimal residual disease to predict early disease response in patients with B-cell acute lymphoblastic leukemia

A longitudinal single-cell atlas of treatment response in pediatric AML

Pediatric acute myeloid leukemia (pAML) is characterized by heterogeneous cellular composition, driver alterations and prognosis. Characterization of this heterogeneity and how it affects treatment response remains understudied in pediatric patients. We used single-cell RNA sequencing and single-cell ATAC sequencing to profile 28 patients representing different pAML subtypes at diagnosis, remission and relapse. At diagnosis, cellular composition differed between genetic subgroups. Upon relapse, cellular hierarchies transitioned toward a more primitive state regardless of subtype. Primitive cells in the relapsed tumor were distinct compared to cells at diagnosis, with under-representation of myeloid transcriptional programs and over-representation of other lineage programs. In some patients, this was accompanied by the appearance of a B-lymphoid-like hierarchy. Our data thus reveal the emergence of apparent subtype-specific plasticity upon treatment and inform on potentially targetable processes.

Various types of electrochemical biosensors for leukemia detection and therapeutic approaches

Leukemia often initiates following dysfunctions in hematopoietic stem cells lineages. Various types of leukemia, including acute lymphoblastic leukemia (ALL), chronic myelogenous leukemia (CML), acute promyelocytic leukemia (APL), and human T-cell leukemia/lymphoma virus type 1 (HTLV-1) can thus call for different diagnosis and treatment options. One of the most important subjects in leukemia is the early detection of the disease for effective therapeutic purposes. In this respect, biosensors detecting the molecules of deoxyribonucleic acid (DNA) as analytes are called genosensors or DNA biosensors. Electrochemical sensors, as the most significant approach, also involve reacting of chemical solutions with sensors to generate electrical signals proportional to analyte concentrations. Biosensors can further help detect cancer cells in the early stages of the disease. Moreover, electrochemical biosensors, developed based on various nanomaterials (NMs), can increase sensitivity to the detection of leukemia-related genes, e.g., BCR/ABL as a fusion gene and promyelocytic leukemia/retinoic acid receptor alpha (PML/RARα). Therefore, the present review reflects on previous studies recruiting different NMs for leukemia detection.

Minimal Residual Disease Detection in Acute Lymphoblastic Leukemia

Minimal residual disease (MRD) refers to a chemotherapy/radiotherapy-surviving leukemia cell population that gives rise to relapse of the disease. The detection of MRD is critical for predicting the outcome and for selecting the intensity of further treatment strategies. The development of various new diagnostic platforms, including next-generation sequencing (NGS), has introduced significant advances in the sensitivity of MRD diagnostics. Here, we review current methods to diagnose MRD through phenotypic marker patterns or differential gene patterns through analysis by flow cytometry (FCM), polymerase chain reaction (PCR), real-time quantitative polymerase chain reaction (RQ-PCR), reverse transcription polymerase chain reaction (RT-PCR) or NGS. Future advances in clinical procedures will be molded by practical feasibility and patient needs regarding greater diagnostic sensitivity.

Early (Day 15 Post Diagnosis) Peripheral Blood Assessment of Measurable Residual Disease in Flow Cytometry is a Strong Predictor of Outcome in Childhood B-Lineage Lymphoblastic Leukemia

BACKGROUND

In children with acute lymphoblastic leukemia (ALL) low levels of minimal residual disease (MRD) after induction, essentially assessed in the bone marrow, have been shown to be of good prognosis. However, only few studies have tested the peripheral blood for MRD.

METHODS

Here, we report the impact on survival of peripheral blood (PB) MRD assessment by multiparameter flow cytometry (MFC) at early time points of treatment in 125 B-ALL children, compared to Day 35 molecular bone marrow (BM) MRD. Patients were sampled for MFC one week postdiagnosis after a pre-phase of corticotherapy (Day 8), then after one week of chemotherapy (Day 15). The study enrolled 67 boys and 58 girls with a median follow-up of 52 months. Over the duration of the study, 20 patients relapsed and eight died. MFC was performed based on the leukemia-associated immunophenotype at diagnosis, using panels of 10 antibodies.

RESULTS

Although, PB MFC-MRD had no prognostic impact at Day 8, Day 15 MRD negativity was associated with a significantly better 4 years DFS (91.6 ± 3% vs. 67.6 ± 9% P = 0.0013). Furthermore, while MFC and molecular data were concordant in most cases, patients with detectable PB MRD on Day 15, yet negative in BM on Day 35 had a significantly lower DFS (P < 0.0001).

CONCLUSION

This study demonstrates that the less invasive procedure of MFC-MRD assessment in PB can be informative for childhood ALL patients at the early point of Day 15 of the treatment schedule. © 2019 International Clinical Cytometry Society.

An aptamer biosensor for leukemia marker mRNA detection based on polymerase-assisted signal amplification and aggregation of illuminator

A novel electrochemical luminescence (ECL) aptamer biosensor via polymerase amplification is constructed for label-free detection of leukemia marker mRNA (miR-16). In order to achieve the ultrasensitive detection of the target mRNA, the cyclic target chain displacement polymerization of leukemia marker mRNA assisted with Klenow fragment of DNA polymerase is employed. The determination is carried out by recording the ECL emission of pyridine ruthenium (Ru(bpy)₃²⁺) complexes embedded into the assistance DNA (ADNA) loaded on the nanogold surface, after the hybridization reaction between the probe DNA (PDNA) and the remaining sequence of the CP's stem part, and the formation of a core-shell sun-like structure. The mercapto-modified capture DNA (CP) is immobilized on the surface of a magneto-controlled glassy carbon electrode by Au-S bond. The CP is opened and hybridized with the target mRNA to form double-stranded DNA. In the presence of polymerase, primer DNA, and bases (dNTPs), the primer chain gets access to its complementary sequence of the stem part and then triggers a polymerization of the DNA strand, leading to the release of mRNA and starting the next polymerization cycle. Finally, the composite of PDNA-covered and ADNA-covered (embedded with Ru(bpy)₃²⁺) gold nanoparticles (hereafter called AuNPs@(PDNA+ADNA-Ru(bpy)₃²⁺) is added, and the ECL intensity is recorded. Because of the polymerization cycle and the aggregation of the illuminator of Ru(bpy)₃²⁺, the detected signal is amplified significantly. The results showed that the corresponding ECL signal has a good linear relationship with a logarithm of target mRNA concentration in the range of 1 × 10^-16 to 1 × 10^-7 mol/L, with a detection limit of 4.3 × 10^-17 mol/L. The mRNA spiked in the human serum sample is determined, and the recoveries are from 97.2 to 102.0%. This sensor demonstrates good selectivity, stability, and reproducibility. Graphical abstract ᅟ.