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HIV infection has been difficult to cure because of uncharacterized reservoirs of infected cells that are resistant to antiretroviral therapy. This study shows that some hematopoietic stem cells are latently infected and may therefore constitute such a reservoir. HIV causes a chronic infection characterized by depletion of CD4 + T lymphocytes and the development of opportunistic infections. Despite drugs that inhibit viral spread, HIV infection has been difficult to cure because of uncharacterized reservoirs of infected cells that are resistant to highly active antiretroviral therapy (HAART) and the immune response. Here we used CD34 + cells from infected people as well as in vitro studies of wild-type HIV to show infection and killing of CD34 + multipotent hematopoietic progenitor cells (HPCs). In some HPCs, we detected latent infection that stably persisted in cell culture until viral gene expression was activated by differentiation factors. A unique reporter HIV that directly detects latently infected cells in vitro confirmed the presence of distinct populations of active and latently infected HPCs. These findings have major implications for understanding HIV bone marrow pathology and the mechanisms by which HIV causes persistent infection.

Effective eradication of leukemic stem cells (LSCs) remains the greatest challenge in treating acute myeloid leukemia (AML). The immune receptor LAIR-1 has been shown to regulate LSC survival; however, the therapeutic potential of this pathway remains unexplored. We developed a therapeutic LAIR-1 agonist antibody, NC525, that induced cell death of LSCs, but not healthy hematopoietic stem cells in vitro, and killed LSCs and AML blasts in both cell- and patient-derived xenograft models. We showed that LAIR-1 agonism drives a unique apoptotic signaling program in leukemic cells that was enhanced in the presence of collagen. NC525 also significantly improved the activity of azacitidine and venetoclax to establish LAIR-1 targeting as a therapeutic strategy for AML that may synergize with standard-of-care therapies.

Clonal haematopoiesis (CH) is a common, age-related expansion of blood cells with somatic mutations that is associated with an increased risk of haematological malignancies, cardiovascular disease and all-cause mortality. CH may be caused by point mutations in genes associated with myeloid neoplasms, chromosomal copy number changes and loss of heterozygosity events. How inherited and environmental factors shape the incidence of CH is incompletely understood. Even though the several varieties of CH may have distinct phenotypic consequences, recent research points to an underlying genetic architecture that is highly overlapping. Moreover, there are numerous commonalities between the inherited variation associated with CH and that which has been linked to age-associated biomarkers and diseases. In this Review, we synthesize what is currently known about how inherited variation shapes the risk of CH and how this genetic architecture intersects with the biology of diseases that occur with ageing.Silver, Bick and Savona discuss our latest understanding of clonal haematopoiesis (CH), which is an expansion of blood cell populations with shared somatic mutations. They focus on human germline risk variants and on how these are linked to different forms of CH and their associated disease pathologies.

The chromatin-associated protein WD Repeat Domain 5 (WDR5) is a promising target for cancer drug discovery, with most efforts blocking an arginine-binding cavity on the protein called the ‘WIN’ site that tethers WDR5 to chromatin. WIN site inhibitors (WINi) are active against multiple cancer cell types in vitro, the most notable of which are those derived from MLL-rearranged (MLLr) leukemias. Peptidomimetic WINi were originally proposed to inhibit MLLr cells via dysregulation of genes connected to hematopoietic stem cell expansion. Our discovery and interrogation of small-molecule WINi, however, revealed that they act in MLLr cell lines to suppress ribosome protein gene (RPG) transcription, induce nucleolar stress, and activate p53. Because there is no precedent for an anticancer strategy that specifically targets RPG expression, we took an integrated multi-omics approach to further interrogate the mechanism of action of WINi in human MLLr cancer cells. We show that WINi induce depletion of the stock of ribosomes, accompanied by a broad yet modest translational choke and changes in alternative mRNA splicing that inactivate the p53 antagonist MDM4. We also show that WINi are synergistic with agents including venetoclax and BET-bromodomain inhibitors. Together, these studies reinforce the concept that WINi are a novel type of ribosome-directed anticancer therapy and provide a resource to support their clinical implementation in MLLr leukemias and other malignancies.

Venetoclax, a BCL-2 inhibitor used to treat certain hematological cancers, exhibits low oral bioavailability and high interpatient pharmacokinetic variability. Venetoclax is commonly administered with prophylactic antifungal drugs that may result in drug interactions, of which the underlying mechanisms remain poorly understood. We hypothesized that antifungal drugs may increase venetoclax exposure through inhibition of both CYP3A-mediated metabolism and OATP1B-mediated transport. Pharmacokinetic studies were performed in wild-type mice and mice genetically engineered to lack all CYP3A isoforms, or OATP1B2 that received venetoclax alone or in combination with ketoconazole or micafungin. In mice lacking all CYP3A isoforms, venetoclax AUC was increased by 1.8-fold, and pretreatment with the antifungal ketoconazole further increased venetoclax exposure by 1.6-fold, despite the absence of CYP3A. Ensuing experiments demonstrated that the deficiency of OATP1B-type transporters is also associated with increases in venetoclax exposure, and that many antifungal drugs, including micafungin, posaconazole, and isavuconazole, are inhibitors of this transport mechanism both in vitro and in vivo. These studies have identified OATP1B-mediated transport as a previously unrecognized contributor to the elimination of venetoclax that is sensitive to inhibition by various clinically-relevant antifungal drugs. Additional consideration is warranted when venetoclax is administered together with agents that inhibit both CYP3A-mediated metabolism and OATP1B-mediated transport.

Clonal hematopoiesis (CH) can be caused by either single gene mutations (eg point mutations in JAK2 causing CHIP) or mosaic chromosomal alterations (e.g., loss of heterozygosity at chromosome 9p). CH is associated with a significantly increased risk of hematologic malignancies. However, the absolute rate of transformation on an annualized basis is low. Improved prognostication of transformation risk is urgently needed for routine clinical practice. We hypothesized that the co-occurrence of CHIP and mCAs at the same locus (e.g., transforming a heterozygous JAK2 CHIP mutation into a homozygous mutation through concomitant loss of heterozygosity at chromosome 9) might have important prognostic implications for malignancy transformation risk. We tested this hypothesis using our discovery cohort, the UK Biobank ( n  = 451,180), and subsequently validated it in the BioVU cohort ( n  = 91,335). We find that individuals with a concurrent somatic mutation and mCA were at significantly increased risk of hematologic malignancy (for example, In BioVU cohort incidence of hematologic malignancies is higher in individuals with co-occurring JAK2 V617F and 9p CN-LOH; HR = 54.76, 95% CI = 33.92–88.41, P  < 0.001 vs. JAK2 V617F alone; HR = 44.05, 95% CI = 35.06–55.35, P  < 0.001). Currently, the ‘zygosity’ of the CHIP mutation is not routinely reported in clinical assays or considered in prognosticating CHIP transformation risk. Based on these observations, we propose that clinical reports should include ‘zygosity’ status of CHIP mutations and that future prognostication systems should take mutation ‘zygosity’ into account.

Umbralisib (TGR-1202) is a novel next-generation inhibitor of phosphatidylinositol 3-kinase (PI3K) isoform p110δ (PI3Kδ), which is structurally distinct from other PI3Kδ inhibitors and shows improved isoform selectivity. Umbralisib also uniquely inhibits casein kinase-1ε, a major regulator of protein translation. The aim of this first-in-human phase 1 study was to establish the safety and preliminary activity profile of umbralisib in patients with haematological malignancies. We did an open-label, phase 1, dose-escalation study at seven clinics in the USA. We recruited patients aged at least 18 years with relapsed or refractory chronic lymphocytic leukaemia or small lymphocytic lymphoma, B-cell and T-cell non-Hodgkin lymphoma, or Hodgkin's lymphoma, who had received one or more previous lines of therapy, with measurable and assessable disease, and adequate organ system function. Patients self-administered an umbralisib oral tablet once per day in 28-day cycles, with dose escalation done in a traditional 3 + 3 design to establish safety and determine the maximum tolerated dose. In initial cohorts, patients took umbralisib in a fasting state at a starting dose of 50 mg, increasing to 100, 200, 400, 800, 1200, and 1800 mg until the maximum tolerated dose was reached, or the maximal dose cohort was accrued without a dose-limiting toxicity. Subsequent cohorts self-administered a micronised formulation of umbralisib tablet in a fed state at an initial dose of 200 mg, increased in increments to 400, 800, 1200, and 1800 mg until the maximum tolerated dose or the maximal dose level was accrued. In August, 2014, all patients still on study were transitioned to 800 mg of the micronised formulation and dosing of the initial formulation was discontinued. The primary endpoints of the study were investigator-assessed safety in all treated patients (the safety population), the maximum tolerated dose, and the pharmacokinetics of umbralisib. Secondary endpoints included preliminary assessments of anti-cancer activity (objective responses and duration of response). Follow-up stopped for a patient once they discontinued therapy. This study has been completed and is registered with ClinicalTrials.gov, number NCT01767766. Between Jan 17, 2013, and Jan 14, 2016, we enrolled and treated 90 patients with umbralisib. The median duration of treatment and follow-up was 4·7 cycles (IQR 2·0–14·0) or 133 days (IQR 55–335). The most common treatment-emergent adverse events irrespective of causality were diarrhoea (in 39 [43%] of 90 patients), nausea (38 [42%]), and fatigue (28 [31%]). The most common grade 3 or 4 adverse events were neutropenia (in 12 [13%] patients), anaemia (eight [9%]) and thrombocytopenia (six [7%]). Serious adverse events considered at least possibly related to umbralisib occurred in seven patients: pneumonia in three (3%) patients, lung infection in one (1%), febrile neutropenia in one (1%), and colitis in two (2%), one of whom also had febrile neutropenia. The maximum tolerated dose was 1200 mg of the micronised formulation, with 800 mg of this formulation selected as the recommended phase 2 dose. Both cases of colitis occurred at above the recommended phase 2 dose. 33 (37%) of the 90 patients enrolled had an objective response to treatment with umbralisib. Umbralisib was well tolerated and showed preliminary signs of activity in patients with relapsed or refractory haematological malignancies. The safety profile of umbralisib in this phase 1 study was distinct from that of other PI3Kδ inhibitors, with fewer occurrences of autoimmune-like toxicities such as colitis. These findings warrant further evaluation of this agent in this setting. TG Therapeutics.

Notable treatment advances have been made in recent years for patients with myelodysplastic syndromes/neoplasms (MDS), and several new drugs are under development. For example, the emerging availability of oral MDS therapies holds the promise of improving patients' health‐related quality of life (HRQoL). Within this rapidly evolving landscape, the inclusion of HRQoL and other patient‐reported outcomes (PROs) is critical to inform the benefit/risk assessment of new therapies or to assess whether patients live longer and better, for what will likely remain a largely incurable disease. We provide practical considerations to support investigators in generating high‐quality PRO data in future MDS trials. We first describe several challenges that are to be thoughtfully considered when designing an MDS‐focused clinical trial with a PRO endpoint. We then discuss aspects related to the design of the study, including PRO assessment strategies. We also discuss statistical approaches illustrating the potential value of time‐to‐event analyses and their implications within the estimand framework. Finally, based on a literature review of MDS randomized controlled trials with a PRO endpoint, we note the PRO items that deserve special attention when reporting future MDS trial results. We hope these practical considerations will facilitate the generation of rigorous PRO data that can robustly inform MDS patient care and support treatment decision‐making for this patient population.

Venetoclax with azacitidine (ven/aza) has emerged as a promising regimen for acute myeloid leukemia (AML), with a high percentage of clinical remissions in newly diagnosed patients. However, approximately 30% of newly diagnosed and the majority of relapsed patients do not achieve remission with ven/aza. 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. Herein we demonstrate that resistance to ven/aza occurs via up-regulation of fatty acid oxidation (FAO), which occurs due to RAS pathway mutations, or as a compensatory adaptation in relapsed disease. Utilization of FAO obviates the need for amino acid metabolism, thereby rendering ven/aza ineffective. Pharmacological inhibition of FAO restores sensitivity to ven/aza in drug resistant AML cells. We propose inhibition of FAO as a therapeutic strategy to address ven/aza resistance.