Blood最新文献

Chronic graft-versus-host disease (cGVHD) remains the leading cause of non-relapse morbidity and mortality after allogeneic hematopoietic cell transplantation (HCT). Effective therapeutics agents targeting dysregulated cytokines including IL-17 and CSF-1 have been defined in preclinical models of cGVHD, and efficacy in subsequent clinical trials has led to their recent FDA approval. Despite this, these agents are effective in only a subset of patients, expensive, difficult to access outside the US, and used in a trial-and-error fashion. The ability to readily discern druggable, dysregulated immunity in these patients is desperately needed to facilitate the selection of appropriate treatment and to potentially identify high-risk individuals for preemptive therapy. We used single cell sequencing-based approaches in our informative preclinical cGVHD models to "reverse engineer" temporal IL-17 and CSF-1 signatures in mouse blood that could be used to interrogate patients. We defined distinct, non-intuitive IL-17 and CSF-1 signatures in mouse blood monocytes that could be identified in relevant monocytes within 70% of patients at diagnosis of cGVHD and in half of patients at day +100 post-HCT who subsequently developed cGVHD. These signatures can now be evaluated prospectively in clinical studies to help delineate potential responder and non-responders to relevant therapeutics targeting these pathways.

Abstract: Langerhans cell histiocytosis (LCH) is a clonal hematopoietic disorder defined by tumorous lesions containing CD1a+/CD207+ cells. Two severe complications of LCH are systemic hyperinflammation and progressive neurodegeneration. The scarcity of primary samples and lack of appropriate models limit our mechanistic understanding of LCH pathogenesis and affect patient care. We generated a human in vitro model for LCH using induced pluripotent stem cells (iPSCs) harboring the BRAFV600E mutation, the most common genetic driver of LCH. We show that BRAFV600E/WT iPSCs display myelomonocytic skewing during hematopoiesis and spontaneously differentiate into CD1a+/CD207+ cells that are similar to lesional LCH cells and are derived from a CD14+ progenitor. We show that BRAFV600E modulates the expression of key transcription factors regulating monocytic differentiation and leads to an upregulation of proinflammatory molecules and LCH marker genes early during myeloid differentiation. In vitro drug testing revealed that BRAFV600E-induced transcriptomic changes are reverted upon treatment with mitogen-activated protein kinase (MAPK) pathway inhibitors (MAPKis). Importantly, MAPKis do not affect myeloid progenitors but reduce only the mature CD14+ cell population. Furthermore, iPSC-derived neurons (iNeurons) cocultured with BRAFV600E/WT iPSC-derived microglia-like cells, differentiated from iPSC-derived CD34+ progenitors, exhibit signs of neurodegeneration with neuronal damage and release of neurofilament light chain. In summary, the iPSC-based model described here provides a platform to investigate the effects of BRAFV600E in different hematopoietic cell types and provides a tool to compare and identify novel approaches for the treatment of BRAFV600E-driven diseases.

Refractory and/or relapsing T-cell acute lymphoblastic leukemia (T-ALL) remains a major therapeutic challenge. The pre-TCR pathway has recently emerged as a therapeutic target via LCK inhibition in this context. However, there is a need for simple and quickly assessable biomarkers to predict sensitivity to LCK inhibitors. Moreover, targeting LCK alone by tyrosine kinase inhibitors, such as Dasatinib, often results in transient clinical responses, emphasizing the need for efficient combination strategies. Here, we assessed pre-TCR alpha chain (pTα) surface expression by flow cytometry in a unique series of 50 adult T-ALL patient-derived xenografts (PDX). We show that cases displaying a cortical phenotype often express high levels of surface pTα (pre-TCR+ T-ALL) and that the latter associates with LCK activation. Furthermore, we show that ectopic interleukin-7 receptor (IL-7R) expression can rescue pre-TCR+ T-ALL from Dasatinib cytotoxicity (5 PDX). We tested whether co-inhibition of pre-TCR and IL-7R signaling pathways could be synergetic in pre-TCR+ IL-7R+ T-ALL (11 PDX). Combination of JAK-inhibitors, Ruxolitinib or Tofacitinib, with Dasatinib elicited strong and specific synergy in IL-7R+ pre-TCR+ T-ALL in vitro, including in the relapse setting (4/28 patient-derived primary samples). Using 3 adult-PDX models, we show that in vivo treatment with this combination significantly delayed leukemic progression and prolonged survival compared to either monotherapy. This preclinical study thus proposes the use of pTα as a biomarker of LCK-inhibitor sensitivity in T-ALL, and suggests that dual targeting of IL-7R and pre-TCR signaling pathways may be a relevant therapeutic strategy in a substantial proportion of adult T-ALL.

Abstract: Detection of light chain (LC) monoclonal gammopathies (MGs) traditionally relies on serum free LC (FLC) κ, λ, and their ratio (κ/λ) reference ranges based on a mostly White population. We investigated FLC values in a racially diverse population by screening 10 035 individuals for heavy chain MG, identifying 9028 negative cases whose FLC were measured. Participants included 4149 from the PROMISE study (United States, n = 2383; South Africa, n = 1766) and 4879 from the Mass General Brigham Biobank, with 44% self-identifying as Black. Using standard FLC reference ranges, 1074 of 10 035 individuals (10.7%) were diagnosed with LC monoclonal gammopathy of undetermined significance (MGUS), with 99% being κ-restricted. In the United States, 14.8% of Black and 4% of White individuals were diagnosed (P < .01). Among US participants of African (AFR) and European (EUR) genetic ancestry, 14.4% AFR and 2.9% EUR were diagnosed (P < .01). Among South Africans (100% Black), 27.8% were diagnosed using standard ranges. To avoid overdiagnosis, we propose a new κ/λ ratio reference range (0.686 to 2.10) for populations of AFR descent with normal renal function, with standard values for κ and λ being 7.97 to 77.50 mg/L and 6.20 to 49.20 mg/L, respectively. This reduces LC-MGUS overdiagnosis by 91% (10.7% vs 0.97%). Using the new reference, LC-MGUS accounts for 8.8% of MGUS cases, with 74% being κ-restricted, consistent with LC myeloma rates. These findings highlight the importance of basing disease definitions, such as MGUS, on diverse populations. Adopting our proposed FLC reference values would reduce MGUS overdiagnosis among Black individuals, avoiding unnecessary financial, psychological, and medical consequences. This study includes data from NCT03689595.