Emapalumab as salvage therapy for adults with malignancy-associated hemophagocytic lymphohistiocytosis.

Not available.

CD8+ T cell metabolic flexibility elicited by CD28-ARS2 axis-driven alternative splicing of PKM supports antitumor immunity.

Metabolic flexibility has emerged as a critical determinant of CD8+ T-cell antitumor activity, yet the mechanisms driving the metabolic flexibility of T cells have not been determined. In this study, we investigated the influence of the nuclear cap-binding complex (CBC) adaptor protein ARS2 on mature T cells. In doing so, we discovered a novel signaling axis that endows activated CD8+ T cells with flexibility of glucose catabolism. ARS2 upregulation driven by CD28 signaling reinforced splicing factor recruitment to pre-mRNAs and affected approximately one-third of T-cell activation-induced alternative splicing events. Among these effects, the CD28-ARS2 axis suppressed the expression of the M1 isoform of pyruvate kinase in favor of PKM2, a key determinant of CD8+ T-cell glucose utilization, interferon gamma production, and antitumor effector function. Importantly, PKM alternative splicing occurred independently of CD28-driven PI3K pathway activation, revealing a novel means by which costimulation reprograms glucose metabolism in CD8+ T cells.

Retrospective characterization of nodal marginal zone lymphoma.

Nodal marginal zone lymphoma (NMZL) is a rare non-Hodgkin B-cell lymphoma that has historically been difficult to define, though is now formally recognized by the World Health Organization Classification. To better characterize the clinical outcomes of patients with NMZL, we reviewed a sequential cohort of 187 patients with NMZL to describe baseline characteristics, survival outcomes, and time-to-event data. Initial management strategies were classified into five categories: observation, radiation, anti-CD20 monoclonal antibody therapy, chemoimmunotherapy, or other. Baseline Follicular Lymphoma International Prognostic Index scores were calculated to evaluate prognosis. A total of 187 patients were analyzed. The five-year overall survival was 91% (95% confidence interval [CI], 87-95), with a median follow-up time of 71 months (range, 8-253) among survivors. A total of 139 patients received active treatment at any point, with a median follow-up time of 56 months (range, 13-253) among survivors who were never treated. The probability of remaining untreated at five years was 25% (95% CI, 19-33). For those initially observed, the median time to active treatment was 72 months (95% CI, 49-not reached). For those who received at least one active treatment, the cumulative incidence of receiving a second active treatment at 60 months was 37%. Transformation to large B-cell lymphoma was rare, with a cumulative incidence of 15% at 10 years. In summary, our series is a large cohort of uniformly diagnosed NMZL with detailed analyses of survival and time to event analyses. We showed that NMZL commonly presents as an indolent lymphoma for which initial observation is often a reasonable strategy.

A multimodal atlas of tumour metabolism reveals the architecture of gene-metabolite covariation.

Tumour metabolism is controlled by coordinated changes in metabolite abundance and gene expression, but simultaneous quantification of metabolites and transcripts in primary tissue is rare. To overcome this limitation and to study gene-metabolite covariation in cancer, we assemble the Cancer Atlas of Metabolic Profiles of metabolomic and transcriptomic data from 988 tumour and control specimens spanning 11 cancer types in published and newly generated datasets. Meta-analysis of the Cancer Atlas of Metabolic Profiles reveals two classes of gene-metabolite covariation that transcend cancer types. The first corresponds to gene-metabolite pairs engaged in direct enzyme-substrate interactions, identifying putative genes controlling metabolite pool sizes. A second class of gene-metabolite covariation represents a small number of hub metabolites, including quinolinate and nicotinamide adenine dinucleotide, which correlate to many genes specifically expressed in immune cell populations. These results provide evidence that gene-metabolite covariation in cellularly heterogeneous tissue arises, in part, from both mechanistic interactions between genes and metabolites, and from remodelling of the bulk metabolome in specific immune microenvironments.

TP53 mutations identify high-risk events for peripheral T-cell lymphoma treated with CHOP-based chemotherapy.

Nodal peripheral T-cell lymphomas (PTCL), the most common PTCLs, are generally treated with cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP)-based curative-intent chemotherapy. Recent molecular data have assisted in prognosticating these PTCLs, but most reports lack detailed baseline clinical characteristics and treatment courses. We retrospectively evaluated cases of PTCL treated with CHOP-based chemotherapy that had tumors sequenced by the Memorial Sloan Kettering Integrated Mutational Profiling of Actionable Cancer Targets next-generation sequencing panel to identify variables correlating with inferior survival. We identified 132 patients who met these criteria. Clinical factors correlating with an increased risk of progression (by multivariate analysis) included advanced-stage disease and bone marrow involvement. The only somatic genetic aberrancies correlating with inferior progression-free survival (PFS) were TP53 mutations and TP53/17p deletions. PFS remained inferior when stratifying by TP53 mutation status, with a median PFS of 4.5 months for PTCL with a TP53 mutation (n = 21) vs 10.5 months for PTCL without a TP53 mutation (n = 111). No TP53 aberrancy correlated with inferior overall survival (OS). Although rare (n = 9), CDKN2A-deleted PTCL correlated with inferior OS, with a median of 17.6 months vs 56.7 months for patients without CDKN2A deletions. This retrospective study suggests that patients with PTCL with TP53 mutations experience inferior PFS when treated with curative-intent chemotherapy, warranting prospective confirmation.

D-2HG comes out of its shell: Metabolic effects on the immune environment.

A recent study by Notarangelo et al.1 highlights the potential for tumor-derived D-2HG to inhibit neighboring T cell function through a novel mechanism.

Mitonuclear genotype remodels the metabolic and microenvironmental landscape of Hürthle cell carcinoma.

Hürthle cell carcinomas (HCCs) display two exceptional genotypes: near-homoplasmic mutation of mitochondrial DNA (mtDNA) and genome-wide loss of heterozygosity (gLOH). To understand the phenotypic consequences of these genetic alterations, we analyzed genomic, metabolomic, and immunophenotypic data of HCC and other thyroid cancers. Both mtDNA mutations and profound depletion of citrate pools are common in HCC and other thyroid malignancies, suggesting that thyroid cancers are broadly equipped to survive tricarboxylic acid cycle impairment, whereas metabolites in the reduced form of NADH-dependent lysine degradation pathway were elevated exclusively in HCC. The presence of gLOH was not associated with metabolic phenotypes but rather with reduced immune infiltration, indicating that gLOH confers a selective advantage partially through immunosuppression. Unsupervised multimodal clustering revealed four clusters of HCC with distinct clinical, metabolomic, and microenvironmental phenotypes but overlapping genotypes. These findings chart the metabolic and microenvironmental landscape of HCC and shed light on the interaction between genotype, metabolism, and the microenvironment in cancer.

GCN2 kinase activation by ATP-competitive kinase inhibitors.

Small-molecule kinase inhibitors represent a major group of cancer therapeutics, but tumor responses are often incomplete. To identify pathways that modulate kinase inhibitor response, we conducted a genome-wide knockout (KO) screen in glioblastoma cells treated with the pan-ErbB inhibitor neratinib. Loss of general control nonderepressible 2 (GCN2) kinase rendered cells resistant to neratinib, whereas depletion of the GADD34 phosphatase increased neratinib sensitivity. Loss of GCN2 conferred neratinib resistance by preventing binding and activation of GCN2 by neratinib. Several other Food and Drug Administration (FDA)-approved inhibitors, such erlotinib and sunitinib, also bound and activated GCN2. Our results highlight the utility of genome-wide functional screens to uncover novel mechanisms of drug action and document the role of the integrated stress response (ISR) in modulating the response to inhibitors of oncogenic kinases.

T cells critically depend on pyruvate oxidation.

Supporting the notion that cell lineage is a key determinant of cancer cell metabolism, Jun et al. (2021) identify a selective requirement for pyruvate dehydrogenase (PDH) activity in T cells and T cell leukemia, but not hematopoietic stem cells (HSCs) or myeloid leukemia, in this issue of Cell Metabolism.

Phase II Trial of Pembrolizumab Plus Gemcitabine, Vinorelbine, and Liposomal Doxorubicin as Second-Line Therapy for Relapsed or Refractory Classical Hodgkin Lymphoma.

PURPOSE: We conducted a phase II study evaluating pembrolizumab plus gemcitabine, vinorelbine, and liposomal doxorubicin (pembro-GVD) as second-line therapy for relapsed or refractory (rel/ref) classical Hodgkin lymphoma (cHL) (ClinicalTrials.gov identifier: NCT03618550). METHODS: Transplant eligible patients with rel/ref cHL following first-line therapy were treated with two to four cycles of pembrolizumab (200 mg intravenous [IV], day 1), gemcitabine (1,000 mg/m2 IV, days 1 and 8), vinorelbine (20 mg/m2 IV, days 1 and 8), and liposomal doxorubicin (15 mg/m2, days 1 and 8), given on 21-day cycles. The primary end point was complete response (CR) following up to four cycles of pembro-GVD. Patients who achieved CR by labeled fluorodeoxyglucose-positron emission tomography (Deauville ≤ 3) after two or four cycles proceeded to high-dose therapy and autologous hematopoietic cell transplantation (HDT/AHCT). HDT/AHCT was carried out according to institutional standards, and brentuximab vedotin maintenance was allowed following HDT/AHCT. RESULTS: Of 39 patients enrolled, 41% had primary ref disease and 38% relapsed within 1 year of frontline treatment. 31 patients received two cycles of pembro-GVD, and eight received four cycles. Most adverse events were grade 1 or two, whereas few were grade 3 and included transaminitis (n = 4), neutropenia (n = 4), mucositis (n = 2), thyroiditis (n = 1), and rash (n = 1). Of 38 evaluable patients, overall and CR rates after pembro-GVD were 100% and 95%, respectively. Thirty-six (95%) patients proceeded to HDT/AHCT, two received pre-HDT/AHCT involved site radiation, and 13 (33%) received post-HDT/AHCT brentuximab vedotin maintenance. All 36 transplanted patients are in remission at a median post-transplant follow-up of 13.5 months (range: 2.66-27.06 months). CONCLUSION: Second-line therapy with pembro-GVD is a highly effective and well-tolerated regimen that can efficiently bridge patients with rel/ref cHL to HDT/AHCT.

In vivo library screening identifies the metabolic enzyme aldolase A as a promoter of metastatic lung colonization.

Elucidations of the factors that promote the growth of disseminated tumor cells (DTCs) into life-threatening lesions stand to provide much needed prognostic and therapeutic targets of translational utility for patients with metastatic cancer. To identify such regulators, we conducted gain-of-function cDNA library screening to discover genes that foster prostate cancer cell colonization of mouse lungs as an experimental model. Our efforts identified the metabolic enzyme aldolase A (ALDOA) as a driver of cancer cell motility, anchorage-independent growth, and metastatic colonization, and as a prognosticator of adverse patient outcome across many malignancies, including prostate, breast, pancreatic, and liver cancers. Metabolomics coupled with biochemical and functional analyses revealed that ALDOA triggered the activation of adenosine-5'-monophosphate (AMP)-activated protein kinase (AMPK), which we demonstrate played essential promalignant activities in ALDOA-expressing cells. Collectively, these findings unveiled vivo approaches to identify metastatic colonization regulators and uncovered previously undescribed roles for ALDOA-AMPK pathway in tumor progression.

Discovery of Protein Modifications Using Differential Tandem Mass Spectrometry Proteomics.

Recent studies have revealed diverse amino acid, post-translational, and noncanonical modifications of proteins in diverse organisms and tissues. However, their unbiased detection and analysis remain hindered by technical limitations. Here, we present a spectral alignment method for the identification of protein modifications using high-resolution mass spectrometry proteomics. Termed SAMPEI for spectral alignment-based modified peptide identification, this open-source algorithm is designed for the discovery of functional protein and peptide signaling modifications, without prior knowledge of their identities. Using synthetic standards and controlled chemical labeling experiments, we demonstrate its high specificity and sensitivity for the discovery of substoichiometric protein modifications in complex cellular extracts. SAMPEI mapping of mouse macrophage differentiation revealed diverse post-translational protein modifications, including distinct forms of cysteine itaconatylation. SAMPEI's robust parametrization and versatility are expected to facilitate the discovery of biological modifications of diverse macromolecules. SAMPEI is implemented as a Python package and is available open-source from BioConda and GitHub (https://github.com/FenyoLab/SAMPEI).

Oncogenic Mechanisms and Therapeutic Targeting of Metabolism in Leukemia and Lymphoma.

Leukemias and lymphomas acquire the capacity for unrestrained cell growth and proliferation in conjunction with loss of responsiveness to molecular programs that promote terminal differentiation. Malignant cells generate the building blocks required for rapid cell division through both increased acquisition of nutrients from the environment and reprogrammed intermediary metabolism to shunt these molecules into producing the protein, lipids, and nucleic acids that comprise cell biomass. These accelerated metabolic processes require energy in the form of ATP and reducing equivalents in the form of NADPH, which power biosynthetic reactions and buffer oxidative stress encountered by the metabolically active cancer cell. Cancer-associated metabolic alterations can also promote accumulation or depletion of specific metabolites that directly regulate cell fate and function, thereby coupling metabolic reprogramming to dedifferentiation and stemness. This review will focus on the mechanisms by which leukemia and lymphoma cells rewire cellular metabolism to support: (1) bioenergetics, (2) biomass accumulation, (3) redox balance, and (4) differentiation blockade. We will further highlight examples of how specific pathways of leukemia and lymphoma metabolism confer therapeutic vulnerabilities that can be targeted to inhibit growth or promote differentiation.

FXR mediates T cell-intrinsic responses to reduced feeding during infection.

Reduced nutrient intake is a widely conserved manifestation of sickness behavior with poorly characterized effects on adaptive immune responses. During infectious challenges, naive T cells encountering their cognate antigen become activated and differentiate into highly proliferative effector T cells. Despite their evident metabolic shift upon activation, it remains unclear how effector T cells respond to changes in nutrient availability in vivo. Here, we show that spontaneous or imposed feeding reduction during infection decreases the numbers of splenic lymphocytes. Effector T cells showed cell-intrinsic responses dependent on the nuclear receptor Farnesoid X Receptor (FXR). Deletion of FXR in T cells prevented starvation-induced loss of lymphocytes and increased effector T cell fitness in nutrient-limiting conditions, but imparted greater weight loss to the host. FXR deficiency increased the contribution of glutamine and fatty acids toward respiration and enhanced cell survival under low-glucose conditions. Provision of glucose during anorexia of infection rescued effector T cells, suggesting that this sugar is a limiting nutrient for activated lymphocytes and that alternative fuel usage may affect cell survival in starved animals. Altogether, we identified a mechanism by which the host scales immune responses according to food intake, featuring FXR as a T cell-intrinsic sensor.

The epigenomics of sarcoma.

Epigenetic regulation is critical to physiological control of development, cell fate, cell proliferation, genomic integrity and, fundamentally, transcriptional regulation. This epigenetic control occurs at multiple levels including through DNA methylation, histone modification, nucleosome remodelling and modulation of the 3D chromatin structure. Alterations in genes that encode chromatin regulators are common among mesenchymal neoplasms, a collection of more than 160 tumour types including over 60 malignant variants (sarcomas) that have unique and varied genetic, biological and clinical characteristics. Herein, we review those sarcomas in which chromatin pathway alterations drive disease biology. Specifically, we emphasize examples of dysregulation of each level of epigenetic control though mechanisms that include alterations in metabolic enzymes that regulate DNA methylation and histone post-translational modifications, mutations in histone genes, subunit loss or fusions in chromatin remodelling and modifying complexes, and disruption of higher-order chromatin structure. Epigenetic mechanisms of tumorigenesis have been implicated in mesenchymal tumours ranging from chondroblastoma and giant cell tumour of bone to chondrosarcoma, malignant peripheral nerve sheath tumour, synovial sarcoma, epithelioid sarcoma and Ewing sarcoma - all diseases that present in a younger patient population than most cancers. Finally, we review current and potential future approaches for the development of sarcoma therapies based on this emerging understanding of chromatin dysregulation.

Nitrogen Trapping as a Therapeutic Strategy in Tumors with Mitochondrial Dysfunction.

Under conditions of inherent or induced mitochondrial dysfunction, cancer cells manifest overlapping metabolic phenotypes, suggesting that they may be targeted via a common approach. Here, we use multiple oxidative phosphorylation (OXPHOS)-competent and incompetent cancer cell pairs to demonstrate that treatment with α-ketoglutarate (aKG) esters elicits rapid death of OXPHOS-deficient cancer cells by elevating intracellular aKG concentrations, thereby sequestering nitrogen from aspartate through glutamic-oxaloacetic transaminase 1 (GOT1). Exhaustion of aspartate in these cells resulted in immediate depletion of adenylates, which plays a central role in mediating mTOR inactivation and inhibition of glycolysis. aKG esters also conferred cytotoxicity in a variety of cancer types if their cell respiration was obstructed by hypoxia or by chemical inhibition of the electron transport chain (ETC), both of which are known to increase aspartate and GOT1 dependencies. Furthermore, preclinical mouse studies suggested that cell-permeable aKG displays a good biosafety profile, eliminates aspartate only in OXPHOS-incompetent tumors, and prevents their growth and metastasis. This study reveals a novel cytotoxic mechanism for the metabolite aKG and identifies cell-permeable aKG, either by itself or in combination with ETC inhibitors, as a potential anticancer approach. SIGNIFICANCE: These findings demonstrate that OXPHOS deficiency caused by either hypoxia or mutations, which can significantly increase cancer virulence, renders tumors sensitive to aKG esters by targeting their dependence upon GOT1 for aspartate synthesis. GRAPHICAL ABSTRACT: http://cancerres.aacrjournals.org/content/canres/80/17/3492/F1.large.jpg.

Specific patterns of H3K79 methylation influence genetic interaction of oncogenes in AML.

Understanding mechanisms of cooperation between oncogenes is critical for the development of novel therapies and rational combinations. Acute myeloid leukemia (AML) cells with KMT2A-fusions and KMT2A partial tandem duplications (KMT2APTD) are known to depend on the histone methyltransferase DOT1L, which methylates histone 3 lysine 79 (H3K79). About 30% of KMT2APTD AMLs carry mutations in IDH1/2 (mIDH1/2). Previous studies showed that 2-hydroxyglutarate produced by mIDH1/2 increases H3K79 methylation, and mIDH1/2 patient samples are sensitive to DOT1L inhibition. Together, these findings suggested that stabilization or increases in H3K79 methylation associated with IDH mutations support the proliferation of leukemias dependent on this mark. However, we found that mIDH1/2 and KMT2A alterations failed to cooperate in an experimental model. Instead, mIDH1/2 and 2-hydroxyglutarate exert toxic effects, specifically on KMT2A-rearranged AML cells (fusions/partial tandem duplications). Mechanistically, we uncover an epigenetic barrier to efficient cooperation; mIDH1/2 expression is associated with high global histone 3 lysine 79 dimethylation (H3K79me2) levels, whereas global H3K79me2 is obligate low in KMT2A-rearranged AML. Increasing H3K79me2 levels, specifically in KMT2A-rearrangement leukemias, resulted in transcriptional downregulation of KMT2A target genes and impaired leukemia cell growth. Our study details a complex genetic and epigenetic interaction of 2 classes of oncogenes, IDH1/2 mutations and KMT2A rearrangements, that is unexpected based on the high percentage of IDH mutations in KMT2APTD AML. KMT2A rearrangements are associated with a trend toward lower response rates to mIDH1/2 inhibitors. The substantial adaptation that has to occur for 2 initially counteracting mutations to be tolerated within the same leukemic cell may provide at least a partial explanation for this observation.

Coordinated alterations in RNA splicing and epigenetic regulation drive leukaemogenesis.

Transcription and pre-mRNA splicing are key steps in the control of gene expression and mutations in genes regulating each of these processes are common in leukaemia1,2. Despite the frequent overlap of mutations affecting epigenetic regulation and splicing in leukaemia, how these processes influence one another to promote leukaemogenesis is not understood and, to our knowledge, there is no functional evidence that mutations in RNA splicing factors initiate leukaemia. Here, through analyses of transcriptomes from 982 patients with acute myeloid leukaemia, we identified frequent overlap of mutations in IDH2 and SRSF2 that together promote leukaemogenesis through coordinated effects on the epigenome and RNA splicing. Whereas mutations in either IDH2 or SRSF2 imparted distinct splicing changes, co-expression of mutant IDH2 altered the splicing effects of mutant SRSF2 and resulted in more profound splicing changes than either mutation alone. Consistent with this, co-expression of mutant IDH2 and SRSF2 resulted in lethal myelodysplasia with proliferative features in vivo and enhanced self-renewal in a manner not observed with either mutation alone. IDH2 and SRSF2 double-mutant cells exhibited aberrant splicing and reduced expression of INTS3, a member of the integrator complex3, concordant with increased stalling of RNA polymerase II (RNAPII). Aberrant INTS3 splicing contributed to leukaemogenesis in concert with mutant IDH2 and was dependent on mutant SRSF2 binding to cis elements in INTS3 mRNA and increased DNA methylation of INTS3. These data identify a pathogenic crosstalk between altered epigenetic state and splicing in a subset of leukaemias, provide functional evidence that mutations in splicing factors drive myeloid malignancy development, and identify spliceosomal changes as a mediator of IDH2-mutant leukaemogenesis.

Metabolic signatures of cancer cells and stem cells.

In contrast to terminally differentiated cells, cancer cells and stem cells retain the ability to re-enter the cell cycle and proliferate. In order to proliferate, cells must increase the uptake and catabolism of nutrients to support anabolic cell growth. Intermediates of central metabolic pathways have emerged as key players that can influence cell differentiation 'decisions', processes relevant for both oncogenesis and normal development. Consequently, how cells rewire metabolic pathways to support proliferation may have profound consequences for cellular identity. Here, we discuss the metabolic programs that support proliferation and explore how metabolic states are intimately entwined with the cell fate decisions that characterize stem cells and cancer cells. By comparing the metabolism of pluripotent stem cells and cancer cells, we hope to illuminate common metabolic strategies as well as distinct metabolic features that may represent specialized adaptations to unique cellular demands.

Isoform Switching as a Mechanism of Acquired Resistance to Mutant Isocitrate Dehydrogenase Inhibition.

Somatic mutations in cytosolic or mitochondrial isoforms of isocitrate dehydrogenase (IDH1 or IDH2, respectively) contribute to oncogenesis via production of the metabolite 2-hydroxyglutarate (2HG). Isoform-selective IDH inhibitors suppress 2HG production and induce clinical responses in patients with IDH1- and IDH2-mutant malignancies. Despite the promising activity of IDH inhibitors, the mechanisms that mediate resistance to IDH inhibition are poorly understood. Here, we describe four clinical cases that identify mutant IDH isoform switching, either from mutant IDH1 to mutant IDH2 or vice versa, as a mechanism of acquired clinical resistance to IDH inhibition in solid and liquid tumors. SIGNIFICANCE: IDH-mutant cancers can develop resistance to isoform-selective IDH inhibition by "isoform switching" from mutant IDH1 to mutant IDH2 or vice versa, thereby restoring 2HG production by the tumor. These findings underscore a role for continued 2HG production in tumor progression and suggest therapeutic strategies to prevent or overcome resistance.This article is highlighted in the In This Issue feature, p. 1494.