A recent Haematology digest,
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Study Type: Preclinical mechanistic study (murine model)

Key Question: Can pharmacological activation of YAP/TAZ in bone marrow niche cells (endothelial cells and mesenchymal stromal cells) accelerate haematopoietic regeneration following myeloablative injury?

Key Findings:

• YAP/TAZ are rapidly upregulated in MSCs and ECs after myeloablative stress, acting as transcriptional regulators that preserve MSC identity (via Ebf1/Ebf3) and sustain CXCL12 and angiogenic factor expression
• YAP/TAZ signalling coordinates sinusoidal vascular remodelling and HSC retention post-myelosuppression; conditional loss impaired haematopoietic recovery
• Pharmacological YAP/TAZ activation enhanced BM niche reorganisation and accelerated haematopoietic regeneration across multiple myelosuppressive models

Clinical Relevance: This identifies a tractable niche-targeted strategy that could reduce post-transplant cytopenias or chemotherapy-related marrow failure — areas of unmet need in UK transplant and intensive chemotherapy programmes.

Limitations: Findings are entirely preclinical (murine); human translatability and pharmacological agent safety profiles require prospective validation.

Study Type: Preclinical mechanistic study (in vitro and patient-derived xenograft models)

Key Question: Does the NG2–ITGA4 signalling axis drive leukemic aggressiveness in KMT2A-rearranged B-ALL, and can natalizumab targeting ITGA4 improve outcomes?

Key Findings:

• NG2 promotes KMT2A-r B-ALL cell proliferation and migration via Rho GTPase activation in an ITGA4-dependent manner
• Combined genetic ablation of NG2 and ITGA4 in immunodeficient mice significantly delayed disease onset and prolonged survival compared to single-gene knockouts
• Natalizumab (EMA-approved anti-ITGA4 monoclonal antibody) delayed leukemia progression and enhanced standard chemotherapy efficacy in PDX models

Clinical Relevance: Natalizumab is already EMA-licensed (for MS and Crohn's disease), making rapid repurposing feasible; this provides preclinical rationale for trials in KMT2A-r B-ALL, a subtype with persistently poor outcomes despite CD19-directed immunotherapy.

Limitations: Findings are entirely preclinical — no human clinical data are presented, and translation to patient benefit remains undemonstrated.

Study Type: Translational study (scRNA-seq, CyTOF, in vitro functional assays, murine in vivo models)

Key Question: Does galectin-1 (Gal-1) drive pathological monocyte-mediated inflammation in MPNs, and does its inhibition ameliorate disease features?

Key Findings:

• scRNA-seq and CyTOF identified Gal-1 overexpression selectively in MPN monocytes; recombinant Gal-1 significantly upregulated proinflammatory cytokine transcription and secretion in CD14+ monocytes from MPN patients
• Gal-1 mediates inflammation via TLR4/NF-κB signalling; TLR4 inhibition abolished Gal-1-driven proinflammatory effects
• Genetic Lgals1 knockout in MPLW515L mice reduced leukocytosis and splenomegaly; Gal-1 inhibition also suppressed carrageenan-induced thrombosis in vivo

Clinical Relevance: Gal-1 represents a potentially actionable therapeutic target in MPNs, where monocyte-driven inflammation contributes to disease burden and thrombotic risk — areas of unmet need beyond current JAK inhibitor therapy.

Limitations: Findings are predominantly preclinical; direct clinical validation in MPN patients is lacking.

Study Type: Translational/mechanistic laboratory study (murine and molecular models)

Key Question: Does post-transcriptional regulation of splicing factor SF1 influence haematopoietic stem cell (HSC) fate decisions?

Key Findings:

• Activity-based profiling of 305 splicing regulators identified widespread post-transcriptional spliceosome modulation in HSCs and progenitor cells
• SF1 translation is controlled by a conserved 5′ UTR structure acting cooperatively with RNA-binding protein IGF2BP2; disrupting this axis reduces SF1 protein and skews differentiation toward stem and erythroid programmes
• SF1-dependent alternative splicing remodels 5′ UTRs of haematopoietic and DNA damage response genes, altering their translation and DNA damage resolution

Clinical Relevance: Identifies a previously unrecognised translational regulatory axis governing HSC fate, with potential implications for understanding dysregulated haematopoiesis in myeloid malignancies and bone marrow failure syndromes relevant to NHS haematology practice.

Limitations: Findings are derived from molecular/murine models; human translational validity and therapeutic applicability remain undemonstrated.

Study Type: RCT (randomised controlled trial)

Key Question: Does adding quizartinib to intensive chemotherapy improve outcomes in older patients (>60 years) with newly diagnosed AML, irrespective of FLT3 mutation status?

Key Findings:

• No overall survival benefit in the unselected population (HR 0.99, 95% CI 0.79–1.24), with increased non-relapse mortality in the quizartinib arm (HR 1.64, 95% CI 1.04–2.59)
• In FLT3-mutated patients (n=116), quizartinib significantly improved OS (HR 0.59, 95% CI 0.37–0.93) and reduced relapse risk (HR 0.57, 95% CI 0.35–0.91)
• FLT3 wild-type patients derived no survival or relapse benefit

Clinical Relevance: This NCRI trial directly informs UK practice: quizartinib should be restricted to FLT3-mutated older AML patients, supporting mutation-directed treatment selection within NHS intensive chemotherapy pathways.

Limitations: FLT3-mutated subgroup analysis was pre-planned but underpowered, limiting definitive conclusions about maintenance duration benefit.

Study Type: Basic science / mechanistic laboratory study

Key Question: What is the mechanism by which the RNA-binding protein IGF2BP1 regulates fetal haemoglobin (HbF) expression during developmental haemoglobin switching?

Key Findings:

• IGF2BP1 activates HIC2 (a BCL11A repressor) via direct binding, providing a mechanistic explanation for its previously described indirect suppression of BCL11A
• IGF2BP1 also directly binds HBG1/2 transcripts to promote fetal globin translation, independent of BCL11A — a novel, previously unrecognised mechanism
• m6A-modified coding sequences near the stop codon of HBG2 are necessary and sufficient for this direct IGF2BP1-mediated upregulation

Clinical Relevance: Understanding post-transcriptional regulators of HbF reactivation may identify novel therapeutic targets for sickle cell disease and beta-thalassaemia, conditions managed across NHS haematology services.

Limitations: Purely mechanistic in vitro/molecular study; no functional validation in patient-derived cells or in vivo disease models is described.

Study Type: Preclinical translational study (murine AML models, single-cell RNA sequencing, CRISPR screen, with human clinical correlation)

Key Question: Does fibroblast-derived FGF18 promote AML progression via stromal-leukemic crosstalk, and can its neutralisation restore anti-tumour immunity?

Key Findings:

• Fibroblast-specific Fgf18 depletion and Fgfr3 loss in AML cells both significantly delayed disease progression and improved murine survival
• FGF18 activates FGFR3/AKT-mTOR/IL-6 signalling in AML cells, creating a feed-forward loop with stromal fibroblasts that suppresses CD8⁺ T-cell effector function
• An anti-FGF18 neutralising antibody synergised with anti-PD-1 therapy to produce durable anti-leukaemic responses in vivo; elevated FGF18 expression correlated with poor prognosis in AML patients

Clinical Relevance: This identifies FGF18 as a potentially actionable stromal target in AML, where outcomes remain poor, and provides rationale for combining FGF18 blockade with existing checkpoint inhibitor strategies.

Limitations: Findings are predominantly murine; clinical correlation is observational only, with no human therapeutic data presented.

Study Type: Preclinical mechanistic study (mouse model with human cell validation)

Key Question: Does iron deficiency regulate vascular endothelial function through modulation of endothelial α-globin and nitric oxide (NO) signalling?

Key Findings:

• Resistance artery endothelial cells carry the lowest iron stores across the vasculature, making them particularly vulnerable to iron deficiency anaemia (IDA)
• IDA increased endothelial NO signalling in female mice; this was reversed by iron dextran repletion — effects were absent in males, attributable to preserved heme-bound (holo) α-globin despite equivalent anaemia severity
• Endothelial-specific α-globin knockout confirmed α-globin loss is necessary for IDA-associated NO upregulation, identifying it as the mechanistic link between vascular iron and vasodilation

Clinical Relevance: Offers a mechanistic basis for the cardiovascular complications of iron deficiency anaemia and raises the possibility that vascular iron status — independent of haemoglobin — is a therapeutic target relevant to IDA management in UK haematology practice.

Limitations: Findings are predominantly from a mouse model; human vascular translation and sex-specific differences require prospective clinical validation.