Analyzing transformation of myelodysplastic syndrome to secondary acute myeloid leukemia using a large patient database

The Genetic Landscape of Myelodysplastic Neoplasm Progression to Acute Myeloid Leukemia

Myelodysplastic neoplasm (MDS) represents a heterogeneous group of myeloid disorders that originate from the hematopoietic stem and progenitor cells that lead to the development of clonal hematopoiesis. MDS was characterized by an increased risk of transformation into acute myeloid leukemia (AML). In recent years, with the aid of next-generation sequencing (NGS), an increasing number of molecular aberrations were discovered, such as recurrent mutations in FLT3, NPM1, DNMT3A, TP53, NRAS, and RUNX1 genes. During MDS progression to leukemia, the order of gene mutation acquisition is not random and is important when considering the prognostic impact. Moreover, the co-occurrence of certain gene mutations is not random; some of the combinations of gene mutations seem to have a high frequency (ASXL1 and U2AF1), while the co-occurrence of mutations in splicing factor genes is rarely observed. Recent progress in the understanding of molecular events has led to MDS transformation into AML and unraveling the genetic signature has paved the way for developing novel targeted and personalized treatments. This article reviews the genetic abnormalities that increase the risk of MDS transformation to AML, and the impact of genetic changes on evolution. Selected therapies for MDS and MDS progression to AML are also discussed.

In Pursuit of Genetic Prognostic Factors and Treatment Approaches in Secondary Acute Myeloid Leukemia—A Narrative Review of Current Knowledge

Secondary acute myeloid leukemia can be divided into two categories: AML evolving from the antecedent hematological condition (AHD-AML) and therapy related AML (t-AML). AHD-AML can evolve from hematological conditions such as myelodysplastic syndromes, myeloproliferative neoplasms, MDS/MPN overlap syndromes, Fanconi anemia, and aplastic anemia. Leukemic transformation occurs as a consequence of the clonal evolution—a process of the acquisition of mutations in clones, while previous mutations are also passed on, leading to somatic mutations accumulation. Compared de novo AML, secondary AML is generally associated with poorer response to chemotherapy and poorer prognosis. The therapeutic options for patients with s-AML have been confirmed to be limited, as s-AML has often been analyzed either both with de novo AML or completely excluded from clinical trials. The treatment of s-AML was not in any way different than de novo AML, until, that is, the introduction of CPX-351—liposomal daunorubicin and cytarabine. CPX-351 significantly improved the overall survival and progression free survival in elderly patients with s-AML. The only definitive treatment in s-AML at this time is allogeneic hematopoietic cell transplantation. A better understanding of the genetics and epigenetics of s-AML would allow us to determine precise biologic drivers leading to leukogenesis and thus help to apply a targeted treatment, improving prognosis.

Should We Look beyond Revised International Prognostic Scoring System: A Retrospective Observational Study of Progression of Myelodysplastic Syndrome to Acute Leukemia

Introduction Myelodysplastic syndrome (MDS) is a clonal stem cell disorder and heterogeneous condition resulting in peripheral cytopenias with marrow dysplasia due to ineffective hematopoiesis. The revised International Prognostic Scoring System (IPSS-R) predicts the risk of progression to acute leukemia (AL). Indian data on MDS and its progression to AL are limited. Additionally, the cytogenetic findings are dictated by patients' racial background. Study intended to analyze the cytogenetic profile of the patients with MDS.

Objectives This study aimed to (1) evaluate the clinicohematologic and morphologic spectrum of newly diagnosed MDS cases, (2) evaluate the cytogenetic profile of these cases, and (3) study the cases progressed to AL.

Materials and Methods MDS cases diagnosed and followed-up during a 5-year study period, from January 2015 to December 2019, were included in the study and the study was conducted at regional cancer center in Western India. De novo diagnosed MDS cases with complete workup were considered and MDS due to secondary causes were excluded. Baseline clinical, hematologic findings were tabulated along with cytogenetics and risk stratified as per IPSS-R, and their progression was studied.

Results A total of 63 cases of de novo MDS were diagnosed over a period of 5 years with 45 cases on follow-up and 15 cases (33.3%) progressed to AL. Maximum number of cases belonged to MDS-excess blast (EB) category accounting to 48 cases (76.1%). Apparently normal karyotyping was the commonest cytogenetic finding in 33 MDS cases (61.2%) and in 8 cases that progressed to AL (53.4%).

Conclusion MDS cases diagnosed at relatively early age were at higher risk of progression to AL. Majority of the cases that progressed to AL were risk stratified in high and very high risk groups and 10 cases which progressed to AL belonged to good category, interestingly apparent normal karyotyping was the commonest cytogenetic finding in more than 50% of the cases progressed to AL. Molecular mutations could only explain this progression and studies integrating molecular mutations with present IPSS-R scoring system should be conducted, as it could translate into better risk stratification and help in early identification and better management of cases at risk in progression to AL.

Co-occurrence of cohesin complex and Ras signaling mutations during progression from myelodysplastic syndromes to secondary acute myeloid leukemia

Myelodysplastic syndromes (MDS) are hematological disorders at high risk of progression to secondary acute myeloid leukemia (sAML). However, the mutational dynamics and clonal evolution underlying disease progression are poorly understood at present. To elucidate the mutational dynamics of pathways and genes occurring during the evolution to sAML, next generation sequencing was performed on 84 serially paired samples of MDS patients who developed sAML (discovery cohort) and 14 paired samples from MDS patients who did not progress to sAML during follow-up (control cohort). Results were validated in an independent series of 388 MDS patients (validation cohort). We used an integrative analysis to identify how mutations, alone or in combination, contribute to leukemic transformation. The study showed that MDS progression to sAML is characterized by greater genomic instability and the presence of several types of mutational dynamics, highlighting increasing (STAG2) and newly-acquired (NRAS and FLT3) mutations. Moreover, we observed cooperation between genes involved in the cohesin and Ras pathways in 15-20% of MDS patients who evolved to sAML, as well as a high proportion of newly acquired or increasing mutations in the chromatin-modifier genes in MDS patients receiving a disease-modifying therapy before their progression to sAML.

The outcomes of secondary AML post allogeneic hematopoietic cell transplantation significantly depend on the presence of poor-risk cytogenetic abnormalities

Secondary acute myeloid leukemia (sAML) includes AML as a complication of an antecedent hematological disorder or a therapy-related AML. Large registry-based data identified sAML as an independent poor-outcome type of AML post allogeneic hematopoietic cell transplantation (allo-HCT). In our study, we tried to define factors affecting outcomes of sAML post allo-HCT, and identify patients with sAML who may truly benefit from allo-HCT. We retrospectively analyzed the data of 64 patients aged (14-61 years) with sAML who received allo-HCT between September 2010 and February 2018 at our institute. Most of the patients were transplanted from matched related donors (MRD; 54, 84.4%). Our results showed that poor-risk cytogenetics were identified in 31 patients (48.4%), and their presence was an indicator of poor overall survival (OS) and disease-free survival (DFS; P-value = .009, and .004, respectively). The cumulative incidence of chronic graft-versus-host disease (cGVHD) was significantly lower in sAML patients with poor-risk cytogenetics (P-value = .003) resulting in a high risk of death without cGVHD in this group of patients (P-value = .02). Besides, GVHD relapse-free survival (GRFS) analysis showed that most of our studied patients experienced either relapse or debilitating grade II-IV cGVHD in the first 2 years post allo-HCT. We conclude that sAML patients with poor-risk cytogenetics have a significantly lower DFS post allo-HCT with a high risk of death without active cGVHD.

Genetic and Genomic Landscape of Secondary and Therapy-Related Acute Myeloid Leukemia

A subset of acute myeloid leukemia (AML) arises either from an antecedent myeloid malignancy (secondary AML, sAML) or as a complication of DNA-damaging therapy for other cancers (therapy-related myeloid neoplasm, t-MN). These secondary leukemias have unique biological and clinical features that distinguish them from de novo AML. Over the last decade, molecular techniques have unraveled the complex subclonal architecture of sAML and t-MN. In this review, we compare and contrast biological and clinical features of de novo AML with sAML and t-MN. We discuss the role of genetic mutations, including those involved in RNA splicing, epigenetic modification, tumor suppression, transcription regulation, and cell signaling, in the pathogenesis of secondary leukemia. We also discuss clonal hematopoiesis in otherwise healthy individuals, as well as in the context of another malignancy, and how it challenges the conventional notion of sAML/t-MN. We conclude by summarizing the current and emerging treatment strategies, including allogenic transplant, in these complex scenarios.

How to address second and therapy-related acute myelogenous leukaemia

Secondary acute myelogenous leukaemia (AML), as compared to de novo AML, occurs in the more elderly population, is independently more resistant to cytotoxic chemotherapy, has a higher relapse rate, and a worse prognosis. Secondary AML (sAML) is a heterogeneous disease, both biologically and clinically, even within the World Health Organization subgroups of sAML. Outcomes are the poorest in subgroups with sAML arising from an antecedent haematologic disorder which has been previously treated (ts-AML), and sAML in patients <55 years of age. This review describes the suboptimal outcomes of contemporary therapy, to support the notion of an unmet need for innovative treatment strategies in sAML. Despite the recent approval of CPX-351, long-term outcomes for this high-risk disease remain dismal. Resistance mechanisms to intensive chemotherapy contribute to relapse. Targeted immune therapy may avoid multidrug resistance mechanisms, but are unlikely to provide long-term remission due to a complex and rapidly evolving clonal disease profile. Advances for sAML will likely be accomplished by CAR T cell therapy or bispecific antibodies providing a bridge to allogeneic stem cell transplantation. Therefore, focus should be placed on novel strategies that can augment the untargeted effector function of allogeneic grafts.

Secondary Acute Myeloid Leukemia: A Primary Challenge of Diagnosis and Treatment

Secondary acute myeloid leukemia (sAML) is a complex diagnosis that includes AML caused by either an antecedent hematologic disease (AML-AHD) or from previous treatment with chemotherapy or radiation. This disease carries a poor prognosis and is historically chemorefractory; additionally, often patients are ineligible for standard chemotherapy because of advanced age and other comorbidities. The advances of molecular diagnostics and reclassification of World Health Organization criteria have aided in the categorization of this disease. This article describes the etiology and pathophysiology of sAML, and delves into past successful treatments as well as promising new treatments.

The leukemia strikes back: a review of pathogenesis and treatment of secondary AML

Secondary AML is associated with a disproportionately poor prognosis, consistently shown to exhibit inferior response rates, event-free survival, and overall survival in comparison with de novo AML. Secondary AML may arise from the evolution of an antecedent hematologic disorder, or it may arise as a complication of prior cytotoxic chemotherapy or radiation therapy in the case of therapy-related AML. Because of the high frequency of poor-risk cytogenetics and high-risk molecular features, such as alterations in TP53, leukemic clones are often inherently chemoresistant. Standard of care induction had long remained conventional 7 + 3 until its reformulation as CPX-351, recently FDA approved specifically for secondary AML. However, recent data also suggests relatively favorable outcomes with regimens based on high-dose cytarabine or hypomethylating agents. With several investigational agents being studied, the therapeutic landscape becomes even more complex, and the treatment approach involves patient-specific, disease-specific, and therapy-specific considerations.

Azacitidine with or without lenalidomide in higher risk myelodysplastic syndrome & low blast acute myeloid leukemia

Standard treatment for higher risk myelodysplastic syndromes, chronic myelomonocytic leukemia and low blast acute myeloid leukemia is azacitidine. In single arm studies, adding lenalidomide had been suggested to improve outcomes. The ALLG MDS4 phase II trial randomized such patients to standard azacitidine or combination azacitidine (75mg/m²/d days 1 to 5) with lenalidomide (10mg days 1–21 of 28-day cycle from cycle 3) to assess clinical benefit (alive without progressive disease) at 12 months. A total of 160 patients were enrolled; median age 70.7 years (range 42.5-87.2), 31.3% female with 14% chronic myelomonocytic leukemia, 12% acute myeloid leukemia and 74% myelodysplastic syndromes. Adverse events were similar in both arms. There was excellent delivery of protocol therapy (median azacitidine cycles 11 both arms) with few dose reductions, delays or early cessations. At median follow up 33.1 months (range 0.7-59.5), the rate of clinical benefit at 12 months was 65% azacitidine arm and 54% lenalidomide+azacitidine arm (P=0.2). There was no difference in clinical benefit between each arm according to WHO diagnostic subgroup or IPSS-R. Overall response rate was 57% in azacitidine arm and 69% in lenalidomide+azacitidine (P=0.14). There was no difference in progression- free or overall survival between the arms (each P>0.12). Although the combination of lenalidomide and azacitidine was tolerable, there was no improvement in clinical benefit, response rates or overall survival in higher risk myelodysplastic syndrome, chronic myelomonocytic leukemia or low blast acute myeloid leukemia patients compared to treatment with azacitidine alone. This trial was registered at www.anzc-tr.org.au as ACTRN12610000271000.

Serotonin receptor type 1B constitutes a therapeutic target for MDS and CMML

Myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML) are chronic myeloid clonal neoplasms. To date, the only potentially curative therapy for these disorders remains allogeneic hematopoietic progenitor cell transplantation (HCT), although patient eligibility is limited due to high morbimortality associated with this procedure coupled with advanced age of most patients. Dopamine receptors (DRs) and serotonin receptors type 1 (HTR1s) were identified as cancer stem cell therapeutic targets in acute myeloid leukemia. Given their close pathophysiologic relationship, expression of HTR1s and DRs was interrogated in MDS and CMML. Both receptors were differentially expressed in patient samples compared to healthy donors. Treatment with HTR1B antagonists reduced cell viability. HTR1 antagonists showed a synergistic cytotoxic effect with currently approved hypomethylating agents in AML cells. Our results suggest that HTR1B constitutes a novel therapeutic target for MDS and CMML. Due to its druggability, the clinical development of new regimens based on this target is promising.

The IPSS-R has prognostic impact in untreated patients with MDS del(5q)

The IPSS-R proved to be a powerful tool for the assessment of prognosis in MDS patients. We aimed at a validation of the IPSS-R for patients with MDS harboring deletion (5q) isolated or accompanied by additional aberrations. The study was based on 444 MDS patients from MDS centers in Europe. 67% of the patients were female, median age was 69 years. 43.5% had MDS del(5q), 5.9% were diagnosed with RCUD, 2.0% RARS, 18.4% RCMD, 14.6% RAEB-I and 15.5% RAEB-II. According to the IPSS-R, there were 9.9% very low, 39.6% low, 16.6% intermediate, 12.8% high, 20.9% very high risk patients. For very low risk patients survival was 7.5 years, low 9.0 years, intermediate 6.5 years, high 1.5 years and very high 0.7 years (p < 0.001). For low and intermediate risk, the probability of AML evolution was significantly different (p = 0.03) as well as for high versus very high risk groups (p = 0.002). The IPSS-R proved to be an appropriate prognostic tool for MDS with del(5q).

Romiplostim monotherapy in thrombocytopenic patients with myelodysplastic syndromes: long-term safety and efficacy

Romiplostim can improve platelet counts in about 50% of patients with low- or intermediate 1-risk (lower risk) myelodysplastic syndromes (MDS) and thrombocytopenia, but its long-term toxicity and efficacy are not known. This open-label extension study evaluated the long-term safety and efficacy of romiplostim in 60 patients with lower risk MDS and platelet counts ≤50 × 109 /l. The primary endpoint was adverse event (AE) incidence. Secondary endpoints were efficacy parameters, including bleeding events and platelet response. Median (range) treatment time in the extension study and the median observation times thereafter were 25 (2-181) and 57 (11-209) weeks, respectively. Treatment-related AEs and serious AEs were reported in 14/60 (23%) and 4/60 (7%) patients, respectively. Progression to acute myeloid leukaemia (AML) occurred in two patients after 44 and 46 weeks. Patients (n = 34, 57%) with a platelet response were further evaluated for length of response. Median (range) response duration was 33 (7-174) weeks; 28/34 (82%) patients had a continuous response. Five of 34 patients (15%) had grade ≥3 bleeding events; three when the platelet count was >50 × 109 /l. There were no new safety concerns and the rate of progression to AML was low; response to romiplostim was maintained for most patients.

Oxidative stress-induced JNK/AP-1 signaling is a major pathway involved in selective apoptosis of myelodysplastic syndrome cells by Withaferin-A

Myelodysplastic syndromes (MDS) are a diverse group of malignant clonal hematopoietic stem cell disorders characterized by ineffective hematopoiesis, dysplastic cell morphology in one or more hematopoietic lineages, and a risk of progression to acute myeloid leukemia (AML). Approximately 50% of MDS patients respond to current FDA-approved drug therapies but a majority of responders relapse within 2-3 years. There is therefore a compelling need to identify potential new therapies for MDS treatment. We utilized the MDS-L cell line to investigate the anticancer potential and mechanisms of action of a plant-derived compound, Withaferin A (WFA), in MDS. WFA was potently cytotoxic to MDS-L cells but had no significant effect on the viability of normal human primary bone marrow cells. WFA also significantly reduced engraftment of MDS-L cells in a xenotransplantation model. Through transcriptome analysis, we identified reactive oxygen species (ROS)-activated JNK/AP-1 signaling as a major pathway mediating apoptosis of MDS-L cells by WFA. We conclude that the molecular mechanism mediating selective cytotoxicity of WFA on MDS-L cells is strongly associated with induction of ROS. Therefore, pharmacologic manipulation of redox biology could be exploited as a selective therapeutic target in MDS.

Treated secondary acute myeloid leukemia: a distinct high-risk subset of AML with adverse prognosis

Secondary acute myeloid leukemia (s-AML) includes therapy-related AML and AML evolving from antecedent hematological disorder (AHD). s-AML arising after treating AHD likely represents a prognostically distinct, high-risk disease category. In this study, treated s-AML (ts-AML) was defined by: (1) prior diagnosis of myelodysplasia, myeloproliferative neoplasm, or aplastic anemia and (2) at least 1 therapy for that diagnosis. ts-AML was categorized by age (< or ≥60 years), and each cohort assessed for response rates and overall survival (OS) on various treatment regimens. Survival outcomes were compared against other high-risk prognostic subsets. Results showed that complete response and 8-week mortality rates were 32% and 27% in the younger, and 24% and 19% in the older age groups, respectively. There was a significant OS difference within s-AML based on prior treatment of AHD (ie, ts-AML vs s-AML with untreated AHD, 4.2 vs 9.2 months; P < .001). Survival in ts-AML was poor across both cohorts (younger and older, 5 and 4.7 months, respectively). In younger AML, survival was significantly inferior in ts-AML when compared with deletion 5/7, TP53, 3q abnormality, and therapy-related AML groups (median, 5 vs 7.9, 7.8, 7.9, and 11.2 months, respectively; P < .01). Additional adverse karyotype within ts-AML was associated with even worse outcomes (OS range, 1.6-2.8 months). ts-AML represents a very high-risk category, even in younger AML patients. s-AML should be further classified to describe ts-AML, an entity less responsive to currently applied treatment approaches. Future AML trial designs should accommodate ts-AML as a distinct subgroup.

Influence of Acute Myeloid Leukemia Progression on the Prognosis of 831 Patients With Myelodysplastic Syndromes From the Argentine Database

BACKGROUND

A large group of patients with myelodysplastic syndromes (MDS) will die of causes intrinsic to bone marrow failure. One third of patients will develop acute myeloid leukemia (AML), which is associated with an extremely poor outcome and a short survival. Our objectives were to analyze the prognostic variables and scoring systems in the attempt to determine the influence of progression on the overall survival of MDS patients.

PATIENTS AND METHODS

We performed a retrospective analysis of 831 MDS patients, including those from the Argentine Registry.

RESULTS

Of the 831 MDS patients, 158 (19.0%) experienced transformation, with a median overall survival of 17.9 months from diagnosis and 3.5 months after progression. The survival of patients with adverse karyotypes or greater risk, according to the International Prognostic Scoring System-revised (IPSS-R) or World Health Organization-based Prognostic Scoring System (WPSS) was not affected when stratified by patients with and without evolution to AML (P > .05). In contrast, the survival of lower risk patients was significantly reduced for those patients with progression to AML (P < .001) and those younger (P = .024) than those who died of non-AML-related causes. The intermediate-risk patients were heterogeneously distributed; however, an upgrade from a lower IPSS-R to a higher WPSS-hemoglobin risk category was associated with a worse outcome, not affected by progression (P = .420), with a median event-free survival of 16 months.

CONCLUSION

The use of the IPSS-R and WPSS systems simultaneously might help in identifying those patients who require more aggressive treatment. Nevertheless, more efforts are needed to improve the identification of those lower risk patients whose survival is significantly reduced by progression to AML.

PP2A inhibition from LB100 therapy enhances daunorubicin cytotoxicity in secondary acute myeloid leukemia via miR-181b-1 upregulation

Patients with secondary acute myeloid leukemia (sAML) arising from myelodysplastic syndromes have a poor prognosis marked by an increased resistance to chemotherapy. An urgent need exists for adjuvant treatments that can enhance or replace current therapeutic options. Here we show the potential of LB100, a small-molecule protein phosphatase 2 A (PP2A) inhibitor, as a monotherapy and chemosensitizing agent for sAML using an in-vitro and in-vivo approach. We demonstrate that LB100 decreases cell viability through caspase activation and G2/M cell-cycle arrest. LB100 enhances daunorubicin (DNR) cytotoxicity resulting in decreased xenograft volumes and improved overall survival. LB100 profoundly upregulates miR-181b-1, which we show directly binds to the 3′ untranslated region of Bcl-2 mRNA leading to its translational inhibition. MiR-181b-1 ectopic overexpression further diminishes Bcl-2 expression leading to suppression of sAML cell growth, and enhancement of DNR cytotoxicity. Our research highlights the therapeutic potential of LB100, and provides new insights into the mechanism of LB100 chemosensitization.

Large-scale gene network analysis reveals the significance of extracellular matrix pathway and homeobox genes in acute myeloid leukemia: an introduction to the Pigengene package and its applications

BACKGROUND

The distinct types of hematological malignancies have different biological mechanisms and prognoses. For instance, myelodysplastic syndrome (MDS) is generally indolent and low risk; however, it may transform into acute myeloid leukemia (AML), which is much more aggressive.

METHODS

We develop a novel network analysis approach that uses expression of eigengenes to delineate the biological differences between these two diseases.

RESULTS

We find that specific genes in the extracellular matrix pathway are underexpressed in AML. We validate this finding in three ways: (a) We train our model on a microarray dataset of 364 cases and test it on an RNA Seq dataset of 74 cases. Our model showed 95% sensitivity and 86% specificity in the training dataset and showed 98% sensitivity and 91% specificity in the test dataset. This confirms that the identified biological signatures are independent from the expression profiling technology and independent from the training dataset. (b) Immunocytochemistry confirms that MMP9, an exemplar protein in the extracellular matrix, is underexpressed in AML. (c) MMP9 is hypermethylated in the majority of AML cases (n=194, Welch's t-test p-value <10^-138), which complies with its low expression in AML. Our novel network analysis approach is generalizable and useful in studying other complex diseases (e.g., breast cancer prognosis). We implement our methodology in the Pigengene software package, which is publicly available through Bioconductor.

CONCLUSIONS

Eigengenes define informative biological signatures that are robust with respect to expression profiling technology. These signatures provide valuable information about the underlying biology of diseases, and they are useful in predicting diagnosis and prognosis.

A Study of Human Leukocyte Antigen Mismatched Cellular Therapy (Stem Cell Microtransplantation) in High-Risk Myelodysplastic Syndrome or Transformed Acute Myelogenous Leukemia

The treatment outcomes of myelodysplastic syndrome (MDS) and transformed acute myelogenous leukemia (tAML) remain very unsatisfactory. We designed a combination of human leukocyte antigen (HLA)-mismatched hematopoietic stem cell microtransplantation (MST) with chemotherapy for patients with MDS and tAML and evaluated its effects and toxicity. Patients were between 13 and 79 years old. Patients with MDS (n=21) were given HLA-mismatched MST combined with decitabine and cytarabine; patients with tAML (n=22) were given HLA-mismatched MST combined with decitabine and cytarabine, and also mitoxantrone. Patients in complete remission (CR) also received MST plus decitabine and medium-dose cytarabine chemotherapy without graft-versus-host disease (GVHD) prophylaxis. The overall response rate of the patients with MDS was significantly higher than that of those with tAML (81% vs. 50%; p=.03). The CR rates were 52.4% and 36.4% in the two groups, respectively. There was no difference in the cytogenetic CR rate between the MDS and tAML groups (85.7% vs. 70%, respectively; p=.7). The 24-month overall survival of the patients with MDS was significantly higher than that of the patients with tAML (84.7% and 34.1%, respectively; p=.003). The median recovery times of neutrophils and platelets were, respectively, 14 and 17 days in the patients with MDS, and 16 and 19 days in those with tAML. The treatment-related mortality rates were 4.8% and 18.2%, respectively, in the MDS and tAML groups (p=.34). No GVHD was observed in any patient. Microtransplantation combined with decitabine and chemotherapy may provide a novel, effective, and safe treatment for high-risk MDS and tAML.

SIGNIFICANCE

Microtransplantation (MST) refers to regular chemotherapy combined with granulocyte colony-stimulating factor-mobilized peripheral blood stem cell infusion of human leukocyte antigen-mismatched donor cells without using immunosuppressive agents. It aims to support hematopoietic recovery and perform graft-versus-leukemia (GVL) effects but differs from traditional allogeneic stem cell transplantation because the rate of donor cell chimerism is low and there is and no graft-versus-host disease (GVHD) risk. Thus, a trial was designed to evaluate the safety and efficacy of MST in patients with myelodysplastic syndrome and those with transformed acute myelogenous leukemia. Higher complete remission and cytogenetic complete response rates were observed, and the treatment improved disease progress-free survival, sped hematopoietic recovery, and avoided GVHD.

Molecular mechanisms of the progression of myelodysplastic syndrome to secondary acute myeloid leukaemia and implication for therapy

Myelodysplastic syndrome (MDS) includes a heterogeneous group of clonal haematological stem cell disorders characterized by dysplasia, cytopenias, ineffective haematopoiesis, and an increased risk of progression to acute myeloid leukaemia (AML), which is also called secondary AML (sAML). Approximately one-third of patients with MDS will progress to sAML within a few months to a few years, and this type of transformation is more common and rapid in patients with high-risk MDS (HR-MDS). However, the precise mechanisms underlying the evolution of MDS to sAML remain unclear. Currently, chemotherapy for sAML has minimal efficacy. The only method of curing patients with sAML is allogeneic haematopoietic stem cell transplantation (Allo-HSCT). Unfortunately, only a few patients are appropriate for transplantation because this disease primarily affects older adult patients. Additionally, compared to de novo AML, sAML is more difficult to cure, and the prognosis is often worse. Therefore, it is important to clarify the molecular mechanisms of the progression of MDS to sAML and to explore the potent drugs for clinical use. This review will highlight several molecular mechanisms of the progression of MDS to sAML and new therapeutic strategies of this disease.

Only three driver gene mutations are required for the development of lung and colorectal cancers

Cancer arises through the sequential accumulation of mutations in oncogenes and tumor suppressor genes. However, how many such mutations are required for a normal human cell to progress to an advanced cancer? The best estimates for this number have been provided by mathematical models based on the relation between age and incidence. For example, the classic studies of Nordling [Nordling CO (1953) Br J Cancer 7(1):68-72] and Armitage and Doll [Armitage P, Doll R (1954) Br J Cancer 8(1):1-12] suggest that six or seven sequential mutations are required. Here, we describe a different approach to derive this estimate that combines conventional epidemiologic studies with genome-wide sequencing data: incidence data for different groups of patients with the same cancer type were compared with respect to their somatic mutation rates. In two well-documented cancer types (lung and colon adenocarcinomas), we find that only three sequential mutations are required to develop cancer. This conclusion deepens our understanding of the process of carcinogenesis and has important implications for the design of future cancer genome-sequencing efforts.