Bcl-xL targeting eliminates ageing tumor-promoting neutrophils and inhibits lung tumor growth.

Elevated peripheral blood and tumor-infiltrating neutrophils are often associated with a poor patient prognosis. However, therapeutic strategies to target these cells are difficult to implement due to the life-threatening risk of neutropenia. In a genetically engineered mouse model of lung adenocarcinoma, tumor-associated neutrophils (TAN) demonstrate tumor-supportive capacities and have a prolonged lifespan compared to circulating neutrophils. Here, we show that tumor cell-derived GM-CSF triggers the expression of the anti-apoptotic Bcl-xL protein and enhances neutrophil survival through JAK/STAT signaling. Targeting Bcl-xL activity with a specific BH3 mimetic, A-1331852, blocked the induced neutrophil survival without impacting their normal lifespan. Specifically, oral administration with A-1331852 decreased TAN survival and abundance, and reduced tumor growth without causing neutropenia. We also show that G-CSF, a drug used to combat neutropenia in patients receiving chemotherapy, increased the proportion of young TANs and augmented the anti-tumor effect resulting from Bcl-xL blockade. Finally, our human tumor data indicate the same role for Bcl-xL on pro-tumoral neutrophil survival. These results altogether provide preclinical evidence for safe neutrophil targeting based on their aberrant intra-tumor longevity.

The metabolic basis of inherited neutropenias.

Neutrophils are the shortest-lived blood cells, which requires a prodigious degree of proliferation and differentiation to sustain physiologically sufficient numbers and be poised to respond quickly to infectious emergencies. More than 107 neutrophils are produced every minute in an adult bone marrow-a process that is tightly regulated by a small group of cytokines and chemical mediators and dependent on nutrients and energy. Like granulocyte colony-stimulating factor, the primary growth factor for granulopoiesis, they stimulate signalling pathways, some affecting metabolism. Nutrient or energy deficiency stresses the survival, proliferation, and differentiation of neutrophils and their precursors. Thus, it is not surprising that monogenic disorders related to metabolism exist that result in neutropenia. Among these are pathogenic mutations in HAX1, G6PC3, SLC37A4, TAFAZZIN, SBDS, EFL1 and the mitochondrial disorders. These mutations perturb carbohydrate, lipid and/or protein metabolism. We hypothesize that metabolic disturbances may drive the pathogenesis of a subset of inherited neutropenias just as defects in DNA damage response do in Fanconi anaemia, telomere maintenance in dyskeratosis congenita and ribosome formation in Diamond-Blackfan anaemia. Greater understanding of metabolic pathways in granulopoiesis will identify points of vulnerability in production and may point to new strategies for the treatment of neutropenias.

From clinical findings to the pathomechanism of poikiloderma with neutropenia.

The clinical problem of a non-healing fistula in ano in a child affected with poikiloderma with neutropenia (PN) was the stimulus for an innovative study by Parajuli et al. that sheds light on the pathological mechanisms in this disease. Multiparametric analyses of the patient's blood mononuclear cells by cell culture, flow cytometry and multiplex cytokine assay suggested a block of monocyte differentiation. Monocyte transcriptome profiling revealed a signature consistent with the haematological picture and the clinical presentation. Commentary on: Parajuli et al. Defective monocyte plasticity and altered cAMP pathway characterize USB1-mutated poikiloderma with neutropenia Clericuzio type. Br J Haematol 2024;204:683-693.

Severe congenital neutropenia, SRP54 pathogenicity, and a framework for surveillance.

Severe congenital neutropenia (SCN) is a rare disorder, often due to pathogenic variants in genes such as ELANE, HAX1, and SBDS. SRP54 pathogenic variants are associated with SCN and Shwachman-Diamond-like syndrome. Thirty-eight patients with SRP54-related SCN are reported in the literature. We present an infant with SCN, without classic Shwachman-Diamond syndrome features, who presented with recurrent bacterial infections and an SRP54 (c.349_351del) pathogenic variant. Despite ongoing granulocyte colony-stimulating factor therapy, this patient has no evidence of malignant transformation. Here we establish a framework for the future development of universal guidelines to care for this patient population.

ELANE neutropenia and solid tumors: Four cases from the French severe chronic neutropenia registry.

Neutropenia related to ELANE gene mutations predisposes patients to infection and leukemia/myelodysplasia, but little is known about the predisposition to cancer. Among a cohort of 147 patients, we identified four with malignant solid tumors (papillary thyroid cancer, anal squamous cell cancer, papillary renal cell carcinoma, and adrenocortical carcinoma), all aged 25-50 years. Three occurred with cyclic neutropenia, and one occurred with severe chronic neutropenia. Previous radiotherapy was identified as a risk factor in one patient. No genetic predisposition was identified in the three other patients.

Heterogeneous genetic landscape of congenital neutropenia in Korean patients revealed by whole exome sequencing: genetic, phenotypic and histologic correlations.

Congenital neutropenia (CN) is a hematological disease heterogeneous in its genetic, phenotypic and histologic aspects. We aimed to identify the genetic etiology of Korean CN patients in the context of bone marrow (BM) histology and clinical phenotype. Whole-exome sequencing (WES) or targeted sequencing was performed on the BM or peripheral blood specimens of 16 patients diagnosed with CN based on BM exam from 2009 to 2018. Absolute count of myeloperoxidase (MPO)-positive cells was calculated using ImageJ software. Semi-quantitation of MPO-positive cells in BM sections was performed by MPO grading (grades 0-3). Comprehensive retrospective review on real-world data of 345 pediatric patients with neutropenia including 16 patients in this study during the same period was performed. Seven disease-causing variants were identified in ELANE, G6PC3 and CXCR4 in 7 patients. A novel homozygous G6PC3 variant (K72fs) of which the mechanism was copy-neutral loss of heterozygosity was detected in two brothers. A low myeloid-to-erythroid ratio (0.5-1.5) was consistently observed in patients with ELANE mutations, while MPO-positive cells (40%-50%) with MPO grade 1 or 2 were detected in myelokathexis caused by G6PC3 and CXCR4 mutations. Meanwhile, disease-causing variants were detected in ELANE, TAZ and SLC37A4 in 5 patients by retrospective review of medical records. Our results suggest that following the immunological study and BM exam, WES or an expanded next generation sequencing panel that covers genes related to immunodeficiency and other inherited bone marrow failures as well as CN is recommended for neutropenia patient diagnosis.

Induction of functional neutrophils from mouse fibroblasts by thymidine through enhancement of Tet3 activity.

Neutrophils are derived from bone marrow hematopoietic stem cells (HSCs) and are the largest population among circulating white blood cells in humans, acting as the first line of defense against invading pathogens. Whether neutrophils can be generated by transdifferentiation strategies is unknown. Here, we show that thymidine induces the conversion of mouse fibroblasts to neutrophils. Induced neutrophils (iNeus) showed antibacterial effects and did not undergo malignant transformation in vivo. Importantly, iNeu transplantation cured neutropenia in mice in vivo. Mechanistically, thymidine mediates iNeu conversion by enhancing Tet3 activity. Tet3 initiates the expression of the neutrophil fate decision factors Cebpδ and Rfx1 that drive the transdifferentiation of mouse fibroblasts to neutrophils. Therefore, the induction of functional neutrophils by chemicals may provide a potential therapeutic strategy for patients with neutropenia patients and infectious diseases.Fibroblasts; Neutrophils; Thymidine; Transdifferentiation; Tet3.

Baseline blood count levels increase odds of cytopenia among CML patients in Kenya: a case control study.

BACKGROUND: Imatinib is the gold standard for the treatment of all phases of Philadelphia positive Chronic Myeloid Leukemia (CML). During treatment, patients may develop cytopenia. We aimed to study the baseline characteristics and factors associated with cytopenia at a Nairobi Hospital. METHODS: This was a retrospective case-control study of patients aged ≥18 years on follow-up at the Glivec International Patient Access Program (GIPAP) clinic from 2007 to 2015. The cases consisted of CML patients on imatinib who developed cytopenia. The controls were CML patients on imatinib who did not develop cytopenia. Baseline socio - demographic, clinical, hematologic, and molecular data were retrieved from patients' files. Chi square or fishers' exact tests were used to analyze for differences between cytopenia and no cytopenia. Binary logistic regressions were employed to identify relationships. Univariate and multivariate analyses were done to identify independent predictors of cytopenia. Odds ratios (OR) were presented including the 95% confidence intervals and respective p values. RESULTS: A total of 201 patients were studied consisting of ninety-four (94) patients with cytopenia and 107 with no cytopenia. Among the entire population, males were 52, and 42% were aged 36-50 years. Sex, age, marital status, occupation and education level were similar between the cytopenia and no cytopenia groups. Among the 201 patients, 70% had symptoms for > 12 months before diagnosis, 78.6% had B symptoms at baseline, 80% had a moderate splenomegaly at baseline. Among patients with cytopenia, 40 and 37.4% developed cytopenia within 3 months and 3-6 months respectively after imatinib initiation. Baseline neutrophilia, neutropenia, anaemia, thrombocytosis, thrombocytopenia was found in 68, 11, 11, 23.5 and 11% respectively. Baseline hemoglobin, neutrophil and platelet level were significantly different between the cytopenia and the no cytopenia group. On univariable analysis, baseline anemia with hb < 7.9 g/dL (p = 0.002), neutropenia (p = 0.001), neutrophilia > 100,000/mm3 (p = 0.002) and thrombocytopenia (p = 0.001) increased the odds of developing cytopenia. On multivariable analysis, baseline anaemia (p value < 0.002), neutropenia (p value < 0.001), thrombocytopenia (p value, < 0.001) and thrombocytosis (p value, 0.033) increased the odds of developing cytopenia. CONCLUSION: Odds of cytopenia were higher in presence of baseline cytopenia and thrombocytosis. Clinicians should have a high index of suspicion for these patients.

Perturbed NK-cell homeostasis associated with disease severity in chronic neutropenia.

Neutrophils have been thought to play a critical role in terminal differentiation of NK cells. Whether this effect is direct or a consequence of global immune changes with effects on NK-cell homeostasis remains unknown. In this study, we used high-resolution flow and mass cytometry to examine NK-cell repertoires in 64 patients with neutropenia and 27 healthy age- and sex-matched donors. A subgroup of patients with chronic neutropenia showed severely disrupted NK-cell homeostasis manifesting as increased frequencies of CD56bright NK cells and a lack of mature CD56dim NK cells. These immature NK-cell repertoires were characterized by expression of the proliferation/exhaustion markers Ki-67, Tim-3, and TIGIT and displayed blunted tumor target cell responses. Systems-level immune mapping revealed that the changes in immunophenotypes were confined to NK cells, leaving T-cell differentiation intact. RNA sequencing of NK cells from these patients showed upregulation of a network of genes, including TNFSF9, CENPF, MKI67, and TOP2A, associated with apoptosis and the cell cycle, but different from the conventional CD56bright signatures. Profiling of 249 plasma proteins showed a coordinated enrichment of pathways related to apoptosis and cell turnover, which correlated with immature NK-cell repertoires. Notably, most of these patients exhibited severe-grade neutropenia, suggesting that the profoundly altered NK-cell homeostasis was connected to the severity of their underlying etiology. Hence, although our data suggest that neutrophils are dispensable for NK-cell development and differentiation, some patients displayed a specific gap in the NK repertoire, associated with poor cytotoxic function and more severe disease manifestations.

Older patients (aged ≥60 years) with previously untreated advanced-stage classical Hodgkin lymphoma: a detailed analysis from the phase III ECHELON-1 study.

Effective and tolerable treatments are needed for older patients with classical Hodgkin lymphoma. We report results for older patients with classical Hodgkin lymphoma treated in the large phase III ECHELON-1 study of frontline brentuximab vedotin plus doxorubicin, vinblastine, and dacarbazine (A+AVD) versus doxorubicin, bleomycin, vinblastine, and dacarbazine (ABVD). Modified progression-free survival per independent review facility for older versus younger patients (aged ≥60 vs. <60 years) was a pre-specified subgroup analysis; as the ECHELON- 1 study was not powered for these analyses, reported P-values are descriptive. Of 1,334 enrolled patients, 186 (14%) were aged ≥60 years (A+AVD: n=84, ABVD: n=102); results below refer to this age group. Modified progression-free survival per independent review facility was similar in the two arms at 24 months (A+AVD: 70.3% [95% confidence interval (CI): 58.4-79.4], ABVD: 71.4% [95% CI: 60.5-79.8], hazard ratio (HR)=1.00 [95% CI: 0.58-1.72], P=0.993). After a median follow-up of 60.9 months, 5-year progression-free survival per investigator was 67.1% with A+AVD versus 61.6% with ABVD (HR=0.820 [95% CI: 0.494-1.362], P=0.443). Comparing A+AVD versus ABVD, grade 3/4 peripheral neuropathy occurred in 18% versus 3%; any-grade febrile neutropenia in 37% versus 17%; and any-grade pulmonary toxicity in 2% versus 13%, respectively, with three (3%) pulmonary toxicity-related deaths in patients receiving ABVD (none in those receiving A+AVD). Altogether, A+AVD showed overall similar efficacy to ABVD with survival rates in both arms comparing favorably to those of prior series in older patients with advanced-stage classical Hodgkin lymphoma. Compared to ABVD, A+AVD was associated with higher rates of neuropathy and neutropenia, but lower rates of pulmonary-related toxicity. Trials registered at ClinicalTrials.gov identifiers: NCT01712490; EudraCT number: 2011-005450-60.

Clinical presentation and natural history of Barth Syndrome: An overview.

Barth Syndrome is a rare X-linked disorder caused by pathogenic variants in the gene TAFAZZIN, which encodes for an enzyme involved in the remodeling of cardiolipin, a phospholipid primarily localized to the inner mitochondrial membrane. Barth Syndrome is characterized by cardiomyopathy, skeletal myopathy, neutropenia, and growth abnormalities, among other features. In this review, we will discuss the clinical presentation and natural history of Barth Syndrome, review key features of this disease, and introduce less common clinical associations. Recognition and understanding of the natural history of Barth Syndrome are important for ongoing patient management and developing endpoints for the demonstration of efficacy of new and emerging therapies.

G-CSF, the guardian of granulopoiesis.

A considerable amount of continuous proliferation and differentiation is required to produce daily a billion new neutrophils in an adult human. Of the few cytokines and factors known to control neutrophil production, G-CSF is the guardian of granulopoiesis. G-CSF/CSF3R signaling involves the recruitment of non-receptor protein tyrosine kinases and their dependent signaling pathways of serine/threonine kinases, tyrosine phosphatases, and lipid second messengers. These pathways converge to activate the families of STAT and C/EBP transcription factors. CSF3R mutations are associated with human disorders of neutrophil production, including severe congenital neutropenia, neutrophilia, and myeloid malignancies. More than three decades after their identification, cloning, and characterization of G-CSF and G-CSF receptor, fundamental questions remain about their physiology.

New insight into the mechanism of granulocyte colony-stimulating factor (G-CSF) that induces the mobilization of neutrophils.

Over the past 20 years, granulocyte colony-stimulating factor (G-CSF) has driven the attention of researchers as a therapeutic agent for curing patients suffering from neutropenia. Despite the successful use of G-CSF, it currently requires daily injections, which are inconvenient, expensive, and distressing for children. Therefore, an alternative strategy for using G-CSF for treatment is needed. Understanding the G-CSF structure, expression, mechanism of action, and how it induces neutrophils mobilization is crucial to producing promising cancer therapy. The ability of G-CSF to mobilize hematopoietic stem cells from the bone marrow into the blood circulation was consequently exploited and altered the practice of hematopoietic stem cell transplantation. This is the motivation for the current review, which sheds light on the history of G-CSF and then focuses on the mechanism of action upon binding to its receptor (G-CSFR) and how that had led to the stimulation of neutrophils mobilization. The findings of this review show new insight into the mechanism of G-CSF that induces neutrophils mobilization. Thus, Understanding the G-CSF will provide a more effective treatment for all neutropenia patients.

Glutathione peroxidase 4-regulated neutrophil ferroptosis induces systemic autoimmunity.

The linkage between neutrophil death and the development of autoimmunity has not been thoroughly explored. Here, we show that neutrophils from either lupus-prone mice or patients with systemic lupus erythematosus (SLE) undergo ferroptosis. Mechanistically, autoantibodies and interferon-α present in the serum induce neutrophil ferroptosis through enhanced binding of the transcriptional repressor CREMα to the glutathione peroxidase 4 (Gpx4, the key ferroptosis regulator) promoter, which leads to suppressed expression of Gpx4 and subsequent elevation of lipid-reactive oxygen species. Moreover, the findings that mice with neutrophil-specific Gpx4 haploinsufficiency recapitulate key clinical features of human SLE, including autoantibodies, neutropenia, skin lesions and proteinuria, and that the treatment with a specific ferroptosis inhibitor significantly ameliorates disease severity in lupus-prone mice reveal the role of neutrophil ferroptosis in lupus pathogenesis. Together, our data demonstrate that neutrophil ferroptosis is an important driver of neutropenia in SLE and heavily contributes to disease manifestations.

CD16+CD163+ monocytes traffic to sites of inflammation during necrotizing enterocolitis in premature infants.

Necrotizing enterocolitis (NEC) is a severe gastrointestinal complication of prematurity. Using suspension and imaging mass cytometry coupled with single-cell RNA sequencing, we demonstrate severe inflammation in patients with NEC. NEC mucosa could be subtyped by an influx of three distinct neutrophil phenotypes (immature, newly emigrated, and aged). Furthermore, CD16+CD163+ monocytes/Mϕ, correlated with newly emigrated neutrophils, were specifically enriched in NEC mucosa, found adjacent to the blood vessels, and increased in circulation of infants with surgical NEC, suggesting trafficking from the periphery to areas of inflammation. NEC-specific monocytes/Mϕ transcribed inflammatory genes, including TREM1, IL1A, IL1B, and calprotectin, and neutrophil recruitment genes IL8, CXCL1, CXCL2, CXCL5 and had enrichment of gene sets in pathways involved in chemotaxis, migration, phagocytosis, and reactive oxygen species generation. In summary, we identify a novel subtype of inflammatory monocytes/Mϕ associated with NEC that should be further evaluated as a potential biomarker of surgical NEC and a target for the development of NEC-specific therapeutics.

Daratumumab plus pomalidomide and dexamethasone versus pomalidomide and dexamethasone alone in previously treated multiple myeloma (APOLLO): an open-label, randomised, phase 3 trial.

BACKGROUND: In a phase 1b study, intravenous daratumumab plus pomalidomide and dexamethasone induced a very good partial response or better rate of 42% and was well tolerated in patients with heavily pretreated multiple myeloma. We aimed to evaluate whether daratumumab plus pomalidomide and dexamethasone would improve progression-free survival versus pomalidomide and dexamethasone alone in patients with previously treated multiple myeloma. METHODS: In this ongoing, open-label, randomised, phase 3 trial (APOLLO) done at 48 academic centres and hospitals across 12 European countries, eligible patients were aged 18 years or older, had relapsed or refractory multiple myeloma with measurable disease, had an Eastern Cooperative Oncology Group performance status of 0-2, had at least one previous line of therapy, including lenalidomide and a proteasome inhibitor, had a partial response or better to one or more previous lines of antimyeloma therapy, and were refractory to lenalidomide if only one previous line of therapy was received. Patients were randomly assigned (1:1) by an interactive web-response system in a random block size of two or four to receive pomalidomide and dexamethasone alone or daratumumab plus pomalidomide and dexamethasone. Randomisation was stratified by number of previous lines of therapy and International Staging System disease stage. All patients received oral pomalidomide (4 mg, once daily on days 1-21) and oral dexamethasone (40 mg once daily on days 1, 8, 15, and 22; 20 mg for those aged 75 years or older) at each 28-day cycle. The daratumumab plus pomalidomide and dexamethasone group received daratumumab (1800 mg subcutaneously or 16 mg/kg intravenously) weekly during cycles 1 and 2, every 2 weeks during cycles 3-6, and every 4 weeks thereafter until disease progression or unacceptable toxicity. The primary endpoint was progression-free survival in the intention-to-treat population. Safety was analysed in all patients who received at least one dose of study medication. This trial is registered with ClinicalTrials.gov, NCT03180736. FINDINGS: Between June 22, 2017, and June 13, 2019, 304 patients (median age 67 years [IQR 60-72]; 161 [53%] men and 143 [47%] women) were randomly assigned to the daratumumab plus pomalidomide and dexamethasone group (n=151) or the pomalidomide and dexamethasone group (n=153). At a median follow-up of 16·9 months (IQR 14·4-20·6), the daratumumab plus pomalidomide and dexamethasone group showed improved progression-free survival compared with the pomalidomide and dexamethasone group (median 12·4 months [95% CI 8·3-19·3] vs 6·9 months [5·5-9·3]; hazard ratio 0·63 [95% CI 0·47-0·85], two-sided p=0·0018). The most common grade 3 or 4 adverse events were neutropenia (101 [68%] of 149 patients in the daratumumab plus pomalidomide and dexamethasone group vs 76 [51%] of 150 patients in the pomalidomide and dexamethasone group), anaemia (25 [17%] vs 32 [21%]), and thrombocytopenia (26 [17%] vs 27 [18%]). Serious adverse events occurred in 75 (50%) of 149 patients in the daratumumab plus pomalidomide and dexamethasone group versus 59 (39%) of 150 patients in the pomalidomide and dexamethasone group; pneumonia (23 [15%] vs 12 [8%] patients) and lower respiratory tract infection (18 [12%] vs 14 [9%]) were most common. Treatment-emergent deaths were reported in 11 (7%) patients in the daratumumab plus pomalidomide and dexamethasone group versus 11 (7%) patients in the pomalidomide and dexamethasone group. INTERPRETATION: Among patients with relapsed or refractory multiple myeloma, daratumumab plus pomalidomide and dexamethasone reduced the risk of disease progression or death versus pomalidomide and dexamethasone alone and could be considered a new treatment option in this setting. FUNDING: European Myeloma Network and Janssen Research and Development.