RAS-mutant AML LSCs originate from GMPs and drive clinical resistance to BH3 mimetics [RNA-Seq]
Ontology highlight
ABSTRACT: Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukemia (AML), upon progression or relapsed/refractory disease1-6. Here, by employing synthetic leukemogenesis in human cells, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors, GMPs) harboring previously acquired driver mutations, revealing that advanced leukemic clones originate from a different cell type than more ancestral clones. Furthermore, we demonstrate that RAS-mutant leukemia stem cells (LSCs) give rise to monocytic disease, as frequently observed in patients with poor responses to treatment with the BCL2 inhibitor drug Venetoclax (VEN). We show that this is because RAS-mutant LSCs, in contrast to RAS-WT LSCs, have altered BCL2 family gene expression profiles and are resistant to VEN, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver by imposing a specific LSC target cell restriction shapes the non-genetic cellular hierarchy of AML and critically impacts therapeutic outcomes in patients.
Project description:Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukemia (AML), upon progression or relapsed/refractory disease1-6. Here, by employing synthetic leukemogenesis in human cells, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors, GMPs) harboring previously acquired driver mutations, revealing that advanced leukemic clones originate from a different cell type than more ancestral clones. Furthermore, we demonstrate that RAS-mutant leukemia stem cells (LSCs) give rise to monocytic disease, as frequently observed in patients with poor responses to treatment with the BCL2 inhibitor drug Venetoclax (VEN). We show that this is because RAS-mutant LSCs, in contrast to RAS-WT LSCs, have altered BCL2 family gene expression profiles and are resistant to VEN, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver by imposing a specific LSC target cell restriction shapes the non-genetic cellular hierarchy of AML and critically impacts therapeutic outcomes in patients.
Project description:Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukemia (AML), upon progression or relapsed/refractory disease1-6. Here, by employing synthetic leukemogenesis in human cells, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors, GMPs) harboring previously acquired driver mutations, revealing that advanced leukemic clones originate from a different cell type than more ancestral clones. Furthermore, we demonstrate that RAS-mutant leukemia stem cells (LSCs) give rise to monocytic disease, as frequently observed in patients with poor responses to treatment with the BCL2 inhibitor drug Venetoclax (VEN). We show that this is because RAS-mutant LSCs, in contrast to RAS-WT LSCs, have altered BCL2 family gene expression profiles and are resistant to VEN, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver by imposing a specific LSC target cell restriction shapes the non-genetic cellular hierarchy of AML and critically impacts therapeutic outcomes in patients.
Project description:Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukemia (AML), upon progression or relapsed/refractory disease1-6. Here, by employing synthetic leukemogenesis in human cells, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors, GMPs) harboring previously acquired driver mutations, revealing that advanced leukemic clones originate from a different cell type than more ancestral clones. Furthermore, we demonstrate that RAS-mutant leukemia stem cells (LSCs) give rise to monocytic disease, as frequently observed in patients with poor responses to treatment with the BCL2 inhibitor drug Venetoclax (VEN). We show that this is because RAS-mutant LSCs, in contrast to RAS-WT LSCs, have altered BCL2 family gene expression profiles and are resistant to VEN, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver by imposing a specific LSC target cell restriction shapes the non-genetic cellular hierarchy of AML and critically impacts therapeutic outcomes in patients.
Project description:Cancer driver mutations often show distinct temporal acquisition patterns, but the biological basis for this, if any, remains unknown. RAS mutations occur invariably late in the course of acute myeloid leukemia (AML), upon progression or relapsed/refractory disease1-6. Here, by employing synthetic leukemogenesis in human cells, we first show that RAS mutations are obligatory late events that need to succeed earlier cooperating mutations. We provide the mechanistic explanation for this in a requirement for mutant RAS to specifically transform committed progenitors of the myelomonocytic lineage (granulocyte-monocyte progenitors, GMPs) harboring previously acquired driver mutations, revealing that advanced leukemic clones originate from a different cell type than more ancestral clones. Furthermore, we demonstrate that RAS-mutant leukemia stem cells (LSCs) give rise to monocytic disease, as frequently observed in patients with poor responses to treatment with the BCL2 inhibitor drug Venetoclax (VEN). We show that this is because RAS-mutant LSCs, in contrast to RAS-WT LSCs, have altered BCL2 family gene expression profiles and are resistant to VEN, driving clinical resistance and relapse with monocytic features. Our findings demonstrate that a specific genetic driver by imposing a specific LSC target cell restriction shapes the non-genetic cellular hierarchy of AML and critically impacts therapeutic outcomes in patients.
Project description:Venetoclax (VEN) has transformed the therapy of acute myeloid leukemia (AML), but resistance and relapse are a major challenge. Monocytic differentiation was proposed as a cause of VEN resistance, but clinical and laboratory evidence is conflicting. Here we harness AML patientderived induced pluripotent stem cells (iPSCs) and Genotyping of Transcriptomes (GoT) to interrogate how mutational status and differentiation stage affect VEN sensitivity independently of one another. Findings in primary and iPSC-derived AML stem cells (LSCs) and monocytic blasts, together with clinical trial data, reveal that monocytic blasts are resistant to VEN, in contrast to LSCs, which express high levels of BCL2 and are sensitive, and that it is the latter, but not the former, that determines the clinical outcome. Crucially, N/KRAS-mutant LSCs produce more monocytic blasts, downregulate BCL2 and are resistant to VEN, driving clinical resistance or relapse. We thus provide a unifying mechanistic model of VEN resistance in AML.
Project description:Therapy resistance represents a major clinical challenge in acute myeloid leukemia (AML). Here we define a “MitoScore” signature that identifies high mitochondrial oxidative phosphorylation (OxPHOS) in vivo and in AML patients. Primary AML cells with cytarabine (AraC) resistance and high MitoScore relied on mitochondrial Bcl2 and were highly sensitive to venetoclax (VEN) plus AraC (but not to VEN plus azacytidine, AZA). Single-cell transcriptomics of VEN+AraC-residual cell populations revealed adaptive resistance associated with changes in OxPHOS, electron transport chain complex (ETC) and the TP53 pathway.
Project description:The combination of venetoclax with azacitidine (ven/aza) has recently emerged as a promising regimen for acute myeloid leukemia (AML), with approximately 70% of newly diagnosed patients achieving complete remission (CR). However, 30% of newly diagnosed and nearly all relapsed patients do not achieve CR with ven/aza. Mechanistically, we previously reported that ven/aza efficacy is based on eradication of AML stem cells through a mechanism involving inhibition of amino acid metabolism, a process which is required in primitive AML cells to drive oxidative phosphorylation. In the present study we demonstrate that resistance to ven/aza occurs as a consequence of up-regulated fatty acid oxidation (FAO), which occurs either as an intrinsic property of RAS pathway mutations, or as a compensatory adaptation in relapsed disease. Utilization of FAO obviates the need for amino acid metabolism into the TCA cycle, thereby rendering ven/aza ineffective. Importantly, we show that pharmacological inhibition of FAO via use of MCL-1 or CPT1 inhibitor drugs restores targeting of ven/aza resistant AML stem cells. Based on these findings we propose that inhibition of FAO is a potential therapeutic strategy to address ven/aza resistance.
Project description:The combination of venetoclax with azacitidine (ven/aza) has recently emerged as a promising regimen for acute myeloid leukemia (AML), with approximately 70% of newly diagnosed patients achieving complete remission (CR). However, 30% of newly diagnosed and nearly all relapsed patients do not achieve CR with ven/aza. Mechanistically, we previously reported that ven/aza efficacy is based on eradication of AML stem cells through a mechanism involving inhibition of amino acid metabolism, a process which is required in primitive AML cells to drive oxidative phosphorylation. In the present study we demonstrate that resistance to ven/aza occurs as a consequence of up-regulated fatty acid oxidation (FAO), which occurs either as an intrinsic property of RAS pathway mutations, or as a compensatory adaptation in relapsed disease. Utilization of FAO obviates the need for amino acid metabolism into the TCA cycle, thereby rendering ven/aza ineffective. Importantly, we show that pharmacological inhibition of FAO via use of MCL-1 or CPT1 inhibitor drugs restores targeting of ven/aza resistant AML stem cells. Based on these findings we propose that inhibition of FAO is a potential therapeutic strategy to address ven/aza resistance.
Project description:Genome-wide analysis of adult and pediatric acute myeloid leukemias (AMLs) revealed distinct mutational profiles characterized by a higher incidence of RAS mutations in young patients. Here we show that the BET inhibitor PLX51107 potently suppresses the growth and promotes apoptosis of NRAS-mutant monocytic AML cell lines, and that these activities are enhanced by co-treatment with the MEK inhibitor PD0325901. Controlled preclinical trials in primary mouse Nras-mutant monocytic AMLs revealed single agent efficacy of PLX51107 that was enhanced by PD0325901. Leukemias that relapsed during treatment developed intrinsic drug resistance characterized by transition to a more primitive state, up-regulation of Myc target genes, and down-regulation of Ras-associated transcriptional programs. AMLs that relapsed after frontline chemotherapy showed similar transcriptional remodeling. These studies demonstrate transcriptional plasticity in primary AMLs that relapse following in vivo treatment with either targeted agents or chemotherapy, and support evaluating BET inhibition in leukemias with monocytic differentiation and RAS mutations.
Project description:Relapse of acute myeloid leukemia (AML) is highly aggressive and often treatment refractory. We analyzed previously published AML relapse cohorts and found that 40% of relapses occur without changes in driver mutations, suggesting that non-genetic mechanisms drive relapse in a large proportion of cases. We therefore characterized epigenetic patterns of AML relapse using 26 matched diagnosis-relapse samples with ATAC-seq. This analysis identified a relapse-specific chromatin accessibility signature for mutationally stable AML, suggesting that AML undergoes epigenetic evolution at relapse independent of mutational changes. Analysis of leukemia stem cell (LSC) chromatin changes at relapse indicated that this leukemic compartment underwent significantly less epigenetic evolution than non-LSCs, while epigenetic changes in non-LSCs reflected overall evolution of the bulk leukemia. Finally, we used single-cell ATAC-seq paired with mitochondrial sequencing (mtscATAC) to map clones from diagnosis into relapse along with their epigenetic features. We found that distinct mitochondrially-defined clones exhibit more similar chromatin accessibility at relapse relative to diagnosis, demonstrating convergent epigenetic evolution in relapsed AML. These results demonstrate that epigenetic evolution is a feature of relapsed AML and that convergent epigenetic evolution can occur following treatment with induction chemotherapy.