Leukemia Research Reports最新文献

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy associated with various combinations of gene mutations, epigenetic abnormalities, and chromosome rearrangement-related gene fusions. Despite the significant degree of heterogeneity in its pathogenesis, many gene fusions and point mutations are recurrent in AML and have been employed in risk stratification over the last several decades. Gene fusions have long been recognized for understanding tumorigenesis and their proven roles in clinical diagnosis and targeted therapies. Advances in DNA sequencing technologies and computational biology have contributed significantly to the detection of known fusion genes as well as for the discovery of novel ones. Several recurring gene fusions in AML have been linked to prognosis, treatment response, and disease progression. In this report, we present a case with a long history of essential thrombocythemia and hallmark CALR mutation transforming to AML characterized by a previously unreported AKAP9::PDGFRA fusion gene. We propose mechanisms by which this fusion may contribute to the pathogenesis of AML and its potential as a molecular target for tyrosine kinase inhibitors.

Introduction

MicroRNAs (miRNAs),are significant regulators of human hematopoietic stem cells. Their deregulation contributes to hematological malignancies.The let-7 family has been found frequently deregulated in malignancies.In MDS various alterations of miRNAs have been reported.High Mobility Group AT-Hook 2 (HMGA2) protein functions as a transcriptional regulator. In this study, we investigated the HMGA2 expression in MDS and specifically in patients with fibrosis we studied the prognostic significance of four members of the let-7 family (let-7a, let-7b, let-7c, let-7d).

Methods

RNA extraction, reverse transcription, anda SYBR Green based real-time PCR were performed for the absolute quantification of HMGA2, using standard protocols. After RNA polyadenylation and reverse transcription with an oligo-dT adapter primer, miRNAs transcript levels were determined using the SYBR Green chemistry. IBM SPSS statistics, version 26 (IBM Corporation, North Castle, NY, USA) was used for the analysis.

Results

HMGA2 gene expression was investigated in 78 patients with MDS, whereas transcript levels of four members of the let-7 family (let-7a, let-7b, let-7c, let-7d) were analyzed in 11 patients with fibrosis. Let-7a transcript levels were significantly higher in MDS patients who developed acute myeloid leukemia (AML) compared to the group that did not (p=0.0141). Let-7d presented a negative correlation (p=0.0408). A moderate (p =0.0483) negative correlation of HMGA2 with let-7c, and a strong positive correlation (p =0.0481) with let-7d, were observed.

Conclusions

In literature, the let-7/HMGA2 linkage could be a signature in MDS pathogenesis. Let-7a level was found higher in transformation to AML,defining it as a poor prognostic factor, in contrast with the protective role of high let-7d.

Introduction

Allogeneic stem cell transplant (alloSCT) remains the only curative treatment for the myelodysplastic syndromes (MDS), but relapse is common. Studies using error-corrected sequencing (ECS) on bulk bone marrow (BM) have shown that molecular residual disease is predictive of relapse. But the sensitivity of this approach is limited, and it is not known what cells give rise to relapse.

Methods

To test our hypothesis that hematopoietic stem cells (HSCs) drive post-transplant relapse, we developed a protocol to perform ECS on as few as <25 HSCs. We used this new tool to ask if post-transplant relapse originates from MDS HSCs, and whether their persistence predicts for relapse. We also sought to determine if curing MDS requires eradication of MDS HSCs, or whether they are simply suppressed by graft-versus-tumor effect.

Results

We sequenced HSCs, multipotent progenitors (MPPs), restricted progenitors, and bulk BM from 33 MDS patients who underwent alloSCT (with an additional 20 specimens to be presented). Persistence of mutations in HSCs/MPPs in the first 120 days post-transplant was 100% specific and 84% sensitive for relapse, while detection of mutations in bulk BM was only 41% sensitive and 85% specific (Figure). Average time from mutation detection in HSCs/MPPs to relapse was 6.9 months.

Conclusions

In conclusion, we have shown for the first time that relapse of MDS after allogeneic transplant is driven by failure to eradicate MDS HSCs, and that detection of MDS HSCs early after transplant is highly predictive for relapse. This can identify patients who may benefit from early post-transplant interventions to forestall relapse.

We report results of a 65-year-old patient with lower-risk myelodysplastic syndrome and multilineage dysplasia treated with hypomethylating agents. After failure of erythropoietin and thalidomide, the patient received azacitidine and achieved hematological remission for 95 months. In 2016, the treatment was switched to decitabine with promising results. These data showed that azacitidine used as a third-line treatment resulted in an exceptionally long-lasting positive hematological response after standard first- and second-line therapies had failed. Additionally, the patient experienced a good quality of life with no complications related to profound cytopenia, and continues to do so at the time of this report's preparation.

Introduction

At many centers, molecular diagnostic (MD) testing for Acute Myeloid Leukemia (AML) struggles to meet turn-around-time (TAT) required for therapeutic decision-making. At our tertiary referral centre, TAT for MD (karyotyping and next-generation sequencing [NGS]) exceeded 4 weeks, resulting in a 'quality gap' in our care pathway for AML. The goal of our study was to improve TAT for MD to optimize care for patients with AML/MDS.

Methods

A multidisciplinary team (hematologists, laboratory scientists, and hematopathologists) defined target TATs for each MD test based on guidelines and available therapies. TAT was evaluated from time of bone marrow to MD reporting. Retrospective review from 2021-2022 was performed to establish baseline time points to compare to post-intervention TATs. Root cause analysis was performed through stakeholder interviews to identify areas contributing to delays in TAT. The primary outcome was the ability to meet target TAT for MD.

Results

Baseline TAT for cytogenetics and NGS varied widely and exceeded targets (Figure 1). Root cause analysis identified lack standardized ordering and testing for patients with AML due to inconsistent decision-maker awareness. Laboratory factors included batching and lack prioritization of AML samples. Interventions included a standardized AML testing algorithm triggered reflexively by flow cytometry at the time diagnosis. Impact of laboratory triggered algorithm for AML testing is shown in Figure 1.

Conclusions

Shared decision-making between hematologists and laboratory practitioners to develop an algorithm for reflex testing and treatment of AML improved TAT. Further improvements are underway to acheive targets, and lessons will be used to inform care pathways for AML/MDS.

Introduction

Myelodysplastic syndromes (MDS) are characterized by persistent of cytopenia, gene abnormalities, and dysplasia. Although the correlation between chronic inflammation and ineffective hematopoiesis is demonstrated in forming MDS pathogenesis, the detailed mechanisms remain unclear.

Methods

Recently, we established a new MDS with low blasts (MDS-LB) model (CBL^ΔE8/9-RUNX1^S291fs mice) , which recapitulates MDS-LB pathogenesis such as pancytopenia and chronic inflammation, by introducing these two mutations into murine hematopoietic stem and progenitor cells (HSC/Ps) .

Results

MDS model mice exhibited excessive mitochondrial fragmentation due to Drp1 activation in HSC/Ps. Importantly, pharmacological inhibition of mitochondrial fragmentation rescued leukocytopenia and dysplasia formation in MDS mice by suppressing inflammatory signaling activation, suggesting that mitochondrial fragmentation could be a new therapeutic target of MDS. Given that mitochondrial fragmentation is related to MDS pathogenesis, we hypothesized that mitochondrial fragmentation can be used for morphological diagnosis of MDS. Differential diagnosis of patients with non-MDS cytopenia and MDS-LB has been challenging. We assessed mitochondrial morphology in bone marrow samples from 10 healthy individuals and 141 patients before disease-modifying therapy. The percentage of cells with mitochondrial fragmentation was significantly increased in patients with MDS-LB, compared with that in patients with cytopenia without dysplasia and gene abnormality (mean 50.7% vs 22.4%, P<0.001, cutoff value 30.8%). The calculated cutoff value clearly distinguishes patients with MDS-LB and non-MDS cytopenia.

Conclusions

These data suggest that mitochondrial fragmentation can be not only a new therapeutic target of MDS-LB but also one category of dysplasia that can diagnose MDS-LB.

Introduction

Myelodysplastic syndrome (MDS) is a heterogeneous constellation of myeloid neoplasms originating from the clonal proliferation of aberrant hematopoietic stem cells (HSC). The human kinome, which comprises over five hundred kinases, plays a critical role in regulating numerous cellular functions. Although the dysregulation of kinases has been observed in various human cancers, the characterization and clinical implications of kinase expressions in MDS have not been investigated before.

Methods

Overall, 341 patients diagnosed with primary MDS according to the 2016 WHO classification, who had adequate cryopreserved diagnostic unsorted bone marrow (BM) samples for DNA and RNA sequencing, were recruited. The normalized gene expressions of a total of 517 kinase gene were studied. We first identified those kinases whose expressions were higher in MDS patients than in healthy controls, and then used LASSO-regularized Cox proportional hazards regression to identify prognostically significant kinases to construct the KInase Stratification Score (KISS).

Results

We discovered that the expression levels of seven kinases (PTK7, KIT, MAST4, NTRK1, PAK6, CAMK1D, PRKCZ) could predict patient outcome, and we used these kinases to construct the KISS; we further validated its prognostic significance in two external MDS cohorts. A higher KISS was associated with older age, higher BM blast percentage, higher IPSS-R risk, complex karyotype, and mutations in several adverse-risk genes in MDS. In the multivariate analysis, a higher KISS was proved to be an independent unfavorable risk factor.

Conclusions

Altogether, our findings suggest that KISS holds the potential to improve the current prognostic scheme of MDS, and inform novel therapeutic opportunities.

Introduction

Despite the significant impact of clonal hematopoiesis (CH) on leukemogenesis, the pathogenesis of CH is still not fully understood.

Methods

Utilizing a novel single-cell sequencing platform that allows for simultaneous detection of mutations and gene expression, we examined the gene expression profiles of hematopoietic stem and progenitor cells (HSPCs) harboring CH-related mutations from CH(+) cases, which was compared with that of wild-type (WT) cells from both CH(+) and CH(−) cases. Age-related changes in the bone marrow (BM) environment were also assessed using CH(−) cases.

Results

In 12 patients with CH, genes associated with cell proliferation were upregulated in mutant cells. Significantly, mutant cells showed decreased expression of genes related to inflammatory responses, which were enhanced in BM cells from aged CH(−) cases, indicating the potential contribution of aged BM environment to the positive selection of mutant cells. Unexpectedly, WT cells from 3 TET2-CH(+) cases demonstrated significant upregulation of genes related to interferon response and cell proliferation, compared with those from age-matched CH(−) cases, suggesting the altered BM environments. Notably, when competitively transplanted with Tet2-knockout (KO) cells, WT HSPCs displayed enhanced expression of genes associated with cell proliferation and interferon signalling, compared with those transplanted with WT cells, implying non-cell autonomous effects of mutant cells.

Conclusions

These results suggest that mutant cells in CH(+) BM may exert non-cell autonomous effects on WT cells. Alongside aged BM environments, these effects may contribute to the positive selection of CH clones, playing a pivotal role in the pathogenesis of CH.