Clonal evolution of hematopoietic stem cells after autologous stem cell transplantation.

The impact of exogenous stressors, such as cancer chemotherapies, on the genomic integrity and clonal dynamics of normal hematopoiesis is not well defined. We conducted whole-genome sequencing on 1,276 single-cell-derived hematopoietic stem and progenitor cell (HSPC) colonies from ten patients with multiple myeloma treated with chemotherapies and six normal donors. Melphalan treatment significantly increased the mutational burden, producing a distinctive mutation signature, whereas other chemotherapeutic agents had minimal effects.

Clinical and molecular features of immunodeficiency in patients with telomere biology disorders.

Immunodeficiency in telomere biology disorders (TBDs) has been described in pediatric patients with severe phenotypes, but is less characterized within the broader TBD spectrum. We collected complete blood counts, lymphocyte subsets, and infection history from 88 consecutive patients with TBD with a median age of 38 years (range, 6-76). Most patients were >18 years old (80/88; 90%) and harbored either a TERT (45%) or TERC germ line mutation (32%).

Natural killer cells' functional impairment drives the immune escape of pre-malignant clones in early-stage myelodysplastic syndromes.

Dissecting the preneoplastic disease states' biological mechanisms that precede tumorigenesis can lead to interventions that can slow down disease progression and/or mitigate disease-related comorbidities. Myelodysplastic syndromes (MDS) cannot be cured by currently available pharmacological therapies, which fail to eradicate aberrant hematopoietic stem cells (HSCs), most of which are mutated by the time of diagnosis. Here, we sought to elucidate how MDS HSCs evade immune surveillance and expand in patients with clonal cytopenias of undetermined significance (CCUS), the pre-malignant stage of MDS.

An integrative multiparametric approach stratifies putative distinct phenotypes of blast phase chronic myelomonocytic leukemia.

Approximately 30% of patients with chronic myelomonocytic leukemia (CMML) undergo transformation to a chemo-refractory blastic phase (BP-CMML). Seeking novel therapeutic approaches, we profiled blast transcriptomes from 42 BP-CMMLs, observing extensive transcriptional heterogeneity and poor alignment to current acute myeloid leukemia (AML) classifications. BP-CMMLs display distinctive transcriptomic profiles, including enrichment for quiescence and variability in drug response signatures.

The IL-1β inhibitor canakinumab in previously treated lower-risk myelodysplastic syndromes: a phase 2 clinical trial.

In myelodysplastic syndromes (MDS), the IL-1β pathway is upregulated, and previous studies using mouse models of founder MDS mutations demonstrated that it enhances hematopoietic stem and progenitor cells' (HSPCs') aberrant differentiation towards the myeloid lineage at the expense of erythropoiesis. To evaluate whether targeting the IL-1β signaling pathway can rescue ineffective erythropoiesis in patients with MDS, we designed a phase 2 non-randomized single-arm clinical trial (NCT04239157) to assess the safety profile and efficacy of the IL-1β inhibitor canakinumab in previously treated lower-risk MDS patients. We enrolled 25 patients with a median age of 74 years; 60% were male, 16% had lower-risk MDS, 84% had intermediate-1 risk MDS according to the International Prognostic Scoring System score, and 80% failed hypomethylating agent therapy.

Inflammation in myelodysplastic syndrome pathogenesis.

Inflammation is a key driver of the progression of preleukemic myeloid conditions, such as clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS), to myelodysplastic syndromes (MDS). Inflammation is a critical mediator in the complex interplay of the genetic, epigenetic, and microenvironmental factors contributing to clonal evolution. Under inflammatory conditions, somatic mutations in TET2, DNMT3A, and ASXL1, the most frequently mutated genes in CHIP and CCUS, induce a competitive advantage to hematopoietic stem and progenitor cells, which leads to their clonal expansion in the bone marrow.

Clonal landscape and clinical outcomes of telomere biology disorders: somatic rescue and cancer mutations.

Telomere biology disorders (TBDs), caused by pathogenic germ line variants in telomere-related genes, present with multiorgan disease and a predisposition to cancer. Clonal hematopoiesis (CH) as a marker of cancer development and survival in TBDs is poorly understood. Here, we characterized the clonal landscape of a large cohort of 207 patients with TBD with a broad range of age and phenotype.

BATF is a major driver of NK cell epigenetic reprogramming and dysfunction in AML.

Myelodysplastic syndrome and acute myeloid leukemia (AML) belong to a continuous disease spectrum of myeloid malignancies with poor prognosis in the relapsed/refractory setting necessitating novel therapies. Natural killer (NK) cells from patients with myeloid malignancies display global dysfunction with impaired killing capacity, altered metabolism, and an exhausted phenotype at the single-cell transcriptomic and proteomic levels. In this study, we identified that this dysfunction was mediated through a cross-talk between NK cells and myeloid blasts necessitating cell-cell contact.

A STAT3 Degrader Demonstrates Pre-clinical Efficacy in Venetoclax resistant Acute Myeloid Leukemia.

Unlabelled: Acute myeloid leukemia (AML) is an aggressive hematologic malignancy that continues to have poor prognosis despite recent therapeutic advances. Venetoclax (Ven), a BCL2-inhibitor has shown a high response rate in AML; however, relapse is invariable due to mitochondrial dysregulation that includes upregulation of the antiapoptotic protein MCL1, a central mechanism of Ven resistance (Ven-res). We have previously demonstrated that the transcription factor STAT3 is upregulated in AML hematopoietic stem and progenitor cells (HSPCs) and can be effectively targeted to induce apoptosis of these aberrant cells.

Clonal evolution of hematopoietic stem cells after cancer chemotherapy.

Normal hematopoietic stem and progenitor cells (HSPCs) inherently accumulate somatic mutations and lose clonal diversity with age, processes implicated in the development of myeloid malignancies . The impact of exogenous stressors, such as cancer chemotherapies, on the genomic integrity and clonal dynamics of normal HSPCs is not well defined. We conducted whole-genome sequencing on 1,032 single-cell-derived HSPC colonies from 10 patients with multiple myeloma (MM), who had undergone various chemotherapy regimens.

Targeting MCL1-driven anti-apoptotic pathways overcomes blast progression after hypomethylating agent failure in chronic myelomonocytic leukemia.

RAS pathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Here, using single-cell, multi-omics technologies, we seek to dissect the biological mechanisms underlying the initiation and progression of RAS pathway-mutated CMML. We identify that RAS pathway mutations induce transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs) and downstream monocytic populations in response to cell-intrinsic and -extrinsic inflammatory signaling that also impair the functions of immune cells.

Hematopoietic stem cells with granulo-monocytic differentiation state overcome venetoclax sensitivity in patients with myelodysplastic syndromes.

The molecular mechanisms of venetoclax-based therapy failure in patients with acute myeloid leukemia were recently clarified, but the mechanisms by which patients with myelodysplastic syndromes (MDS) acquire secondary resistance to venetoclax after an initial response remain to be elucidated. Here, we show an expansion of MDS hematopoietic stem cells (HSCs) with a granulo-monocytic-biased transcriptional differentiation state in MDS patients who initially responded to venetoclax but eventually relapsed. While MDS HSCs in an undifferentiated cellular state are sensitive to venetoclax treatment, differentiation towards a granulo-monocytic-biased transcriptional state, through the acquisition or expansion of clones with STAG2 or RUNX1 mutations, affects HSCs' survival dependence from BCL2-mediated anti-apoptotic pathways to TNFα-induced pro-survival NF-κB signaling and drives resistance to venetoclax-mediated cytotoxicity.

STAT3 protects hematopoietic stem cells by preventing activation of a deleterious autocrine type-I interferon response.

Hematopoietic stem and progenitor cells (HSPCs) maintain blood-forming and immune activity, yet intrinsic regulators of HSPCs remain elusive. STAT3 function in HSPCs has been difficult to dissect as Stat3-deficiency in the hematopoietic compartment induces systemic inflammation, which can impact HSPC activity. Here, we developed mixed bone marrow (BM) chimeric mice with inducible Stat3 deletion in 20% of the hematopoietic compartment to avoid systemic inflammation.

Targeting DNA2 overcomes metabolic reprogramming in multiple myeloma.

DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover mechanisms through which MM cells overcome DNA damage, we investigate how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting Interleukin enhancer binding factor 2 (ILF2), a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo adaptive metabolic rewiring to restore energy balance and promote survival in response to DNA damage activation.

Oral decitabine plus cedazuridine and venetoclax in patients with higher-risk myelodysplastic syndromes or chronic myelomonocytic leukaemia: a single-centre, phase 1/2 study.

Background: Hypomethylating agents are approved in higher-riskmyelodysplastic syndromes. The combination of a hypomethylating agent with venetoclax is standard of care in acute myeloid leukaemia. We investigated the safety and activity of the first totally oral combination of decitabine plus cedazuridine and venetoclax in patients with higher-risk-myelodysplastic syndromes and chronic myelomonocytic leukaemia.

T-cell dysfunctions in myelodysplastic syndromes.

Escape from immune surveillance is a hallmark of cancer. Immune deregulation caused by intrinsic and extrinsic cellular factors, such as altered T-cell functions, leads to immune exhaustion, loss of immune surveillance, and clonal proliferation of tumoral cells. The T-cell immune system contributes to the pathogenesis, maintenance, and progression of myelodysplastic syndrome (MDS).

IL-1β-mediated inflammatory signaling drives ineffective erythropoiesis in early-stage myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are a group of incurable hematopoietic stem cell (HSC) neoplasms characterized by peripheral blood cytopenias and a high risk of progression to acute myeloid leukemia. MDS represent the final stage in a continuum of HSCs' genetic and functional alterations and are preceded by a premalignant phase, clonal cytopenia of undetermined significance (CCUS). Dissecting the mechanisms of CCUS maintenance may uncover therapeutic targets to delay or prevent malignant transformation.

Co-targeting BCL-XL and BCL-2 by PROTAC 753B eliminates leukemia cells and enhances efficacy of chemotherapy by targeting senescent cells.

BCL-XL and BCL-2 are key anti-apoptotic proteins and validated cancer targets. 753B is a novel BCL-XL/BCL-2 proteolysis targeting chimera (PROTAC) that targets both BCL-XL and BCL-2 to the von Hippel-Lindau (VHL) E3 ligase, leading to BCLX L/BCL-2 ubiquitination and degradation selectively in cells expressing VHL. Because platelets lack VHL expression, 753B spares on-target platelet toxicity caused by the first-generation dual BCL-XL/BCL-2 inhibitor navitoclax (ABT-263).

Targeting MCL1-driven anti-apoptotic pathways to overcome hypomethylating agent resistance in -mutated chronic myelomonocytic leukemia.

pathway mutations, which are present in 30% of patients with chronic myelomonocytic leukemia (CMML) at diagnosis, confer a high risk of resistance to and progression after hypomethylating agent (HMA) therapy, the current standard of care for the disease. Using single-cell, multi-omics technologies, we sought to dissect the biological mechanisms underlying the initiation and progression of pathway-mutated CMML. We found that pathway mutations induced the transcriptional reprogramming of hematopoietic stem and progenitor cells (HSPCs), which underwent proliferation and monocytic differentiation in response to cell-intrinsic and -extrinsic inflammatory signaling that also impaired immune cells' functions.

Targeting DNA2 Overcomes Metabolic Reprogramming in Multiple Myeloma.

Unlabelled: DNA damage resistance is a major barrier to effective DNA-damaging therapy in multiple myeloma (MM). To discover novel mechanisms through which MM cells overcome DNA damage, we investigated how MM cells become resistant to antisense oligonucleotide (ASO) therapy targeting ILF2, a DNA damage regulator that is overexpressed in 70% of MM patients whose disease has progressed after standard therapies have failed. Here, we show that MM cells undergo an adaptive metabolic rewiring and rely on oxidative phosphorylation to restore energy balance and promote survival in response to DNA damage activation.

STAT3 protects HSCs from intrinsic interferon signaling and loss of long-term blood-forming activity.

STAT3 function in hematopoietic stem and progenitor cells (HSPCs) has been difficult to discern as deficiency in the hematopoietic system induces systemic inflammation, which can impact HSPC activity. To address this, we established mixed bone marrow (BM) chimeric mice with CreER-mediated deletion in 20% of the hematopoietic compartment. -deficient HSPCs had impaired hematopoietic activity and failed to undergo expansion in BM in contrast to -sufficient (CreER) controls.

Emerging treatments for myelodysplastic syndromes: Biological rationales and clinical translation.

Myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal hematopoietic stem cell disorders characterized by myeloid dysplasia, peripheral blood cytopenias, and increased risk of progression to acute myeloid leukemia (AML). The standard of care for patients with MDS is hypomethylating agent (HMA)-based therapy; however, nearly 50% of patients have no response to the treatment. Patients with MDS in whom HMA therapy has failed have a dismal prognosis and no approved second-line therapy options, so enrollment in clinical trials of experimental agents represents these patients' only chance for improved outcomes.