After 95 years, it's time to eRASe JMML

A lasso and random forest model using flow cytometry data identifies primary myelofibrosis

Thrombocythemia (ET), polycythemia vera (PV), primary myelofibrosis (PMF), prefibrotic/early (pre-PMF), and overt fibrotic PMF (overt PMF) are classical Philadelphia-Negative (Ph-negative) myeloproliferative neoplasms (MPNs). Differentiating between these types based on morphology and molecular markers is challenging. This study aims to clarify the application of flow cytometry in the diagnosis and differential diagnosis of classical MPNs. This study retrospectively analyzed the immunophenotypes, clinical characteristics, and laboratory findings of 211 Ph-negative MPN patients, including ET, PV, pre-PMF, overt PMF, and 47 controls. Compared to ET and PV, PMF differed in white blood cells, hemoglobin, blast cells in the peripheral blood, abnormal karyotype, and WT1 gene expression. PMF also differed from controls in CD34+ cells, granulocyte phenotype, monocyte phenotype, percentage of plasma cells, and dendritic cells. Notably, the PMF group had a significantly lower plasma cell percentage compared with other groups. A lasso and random forest model select five variables (CD34+CD19+cells and CD34+CD38- cells on CD34+cells, CD13dim+CD11b- cells in granulocytes, CD38str+CD19+/-plasma, and CD123+HLA-DR-basophils), which identify PMF with a sensitivity and specificity of 90%. Simultaneously, a classification and regression tree model was constructed using the percentage of CD34+CD38- on CD34+ cells and platelet counts to distinguish between ET and pre-PMF, with accuracies of 94.3% and 83.9%, respectively. Flow immunophenotyping aids in diagnosing PMF and differentiating between ET and PV. It also helps distinguish pre-PMF from ET and guides treatment decisions.

NLRP3 inflammasome activation and symptom burden in KRAS-mutated CMML patients is reverted by IL-1 blocking therapy

Chronic myelomonocytic leukemia (CMML) is frequently associated with mutations in the rat sarcoma gene (RAS), leading to worse prognosis. RAS mutations result in active RAS-GTP proteins, favoring myeloid cell proliferation and survival and inducing the NLRP3 inflammasome together with the apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), which promote caspase-1 activation and interleukin (IL)-1β release. Here, we report, in a cohort of CMML patients with mutations in KRAS, a constitutive activation of the NLRP3 inflammasome in monocytes, evidenced by ASC oligomerization and IL-1β release, as well as a specific inflammatory cytokine signature. Treatment of a CMML patient with a KRASG12D mutation using the IL-1 receptor blocker anakinra inhibits NLRP3 inflammasome activation, reduces monocyte count, and improves the patient's clinical status, enabling a stem cell transplant. This reveals a basal inflammasome activation in RAS-mutated CMML patients and suggests potential therapeutic applications of NLRP3 and IL-1 blockers.

[Clinical features and prognosis of juvenile myelomonocytic leukemia: an analysis of 63 cases]

OBJECTIVES

To investigate the clinical features of juvenile myelomonocytic leukemia (JMML) and their association with prognosis.

METHODS

Clinical and prognosis data were collected from the children with JMML who were admitted from January 2008 to December 2016, and the influencing factors for prognosis were analyzed.

RESULTS

A total of 63 children with JMML were included, with a median age of onset of 25 months and a male/female ratio of 3.2∶1. JMML genetic testing was performed for 54 children, and PTPN11 mutation was the most common mutation and was observed in 23 children (43%), among whom 19 had PTPN11 mutation alone and 4 had compound PTPN11 mutation, followed by NRAS mutation observed in 14 children (26%), among whom 12 had NRAS mutation alone and 2 had compound NRAS mutation. The 5-year overall survival (OS) rate was only 22%±10% in these children with JMML. Of the 63 children, 13 (21%) underwent hematopoietic stem cell transplantation (HSCT). The HSCT group had a significantly higher 5-year OS rate than the non-HSCT group (46%±14% vs 29%±7%, P<0.05). There was no significant difference in the 5-year OS rate between the children without PTPN11 gene mutation and those with PTPN11 gene mutation (30%±14% vs 27%±10%, P>0.05). The Cox proportional-hazards regression model analysis showed that platelet count <40×10⁹/L at diagnosis was an influencing factor for 5-year OS rate in children with JMML (P<0.05).

CONCLUSIONS

The PTPN11 gene was the most common mutant gene in JMML. Platelet count at diagnosis is associated with the prognosis in children with JMML. HSCT can improve the prognosis of children with JMML.

High serum cystatin C levels in juvenile myelomonocytic leukemia patients without abnormal kidney function

BACKGROUND

In pediatric cancer patients, the estimated glomerular filtration rate based on serum cystatin C (CysC) was reported to be suitable for estimating kidney function because of low serum creatinine (Cr) and high serum β₂-microglobulin. Recently, however, serum CysC levels have been reported to be elevated in some cancer patients other than those with juvenile myelomonocytic leukemia (JMML), regardless of normal kidney function.

CASE REPORTS

We describe two pediatric cases of JMML with an elevated serum CysC level. Urinalysis tests showed no abnormalities and no evidence of nephritis or nephropathy, and there were no findings indicating abnormal kidney function, such as Cr clearance in one case or the estimated glomerular filtration rate based on serum Cr in both cases, except for the serum CysC levels. There were no other causes of a high serum CysC level, including hyperthyroidism and steroid administration. The patients were treated with a conventional dosage of drugs, and their serum CysC levels decreased to the normal range when they were in complete remission after treatment.

CONCLUSION

An elevated serum CysC level may reflect tumor burden independent of kidney function in JMML patients. Therefore, creatinine or inulin clearance should be determined to more accurately estimate kidney function for administering an optimal dose of anticancer drugs. In addition, a high serum CysC level may be a potential biomarker of cancer progression.

Increasing Complexity of Molecular Landscapes in Human Hematopoietic Stem and Progenitor Cells during Development and Aging

The past five decades have seen significant progress in our understanding of human hematopoiesis. This has in part been due to the unprecedented development of advanced technologies, which have allowed the identification and characterization of rare subsets of human hematopoietic stem and progenitor cells and their lineage trajectories from embryonic through to adult life. Additionally, surrogate in vitro and in vivo models, although not fully recapitulating human hematopoiesis, have spurred on these scientific advances. These approaches have heightened our knowledge of hematological disorders and diseases and have led to their improved diagnosis and therapies. Here, we review human hematopoiesis at each end of the age spectrum, during embryonic and fetal development and on aging, providing exemplars of recent progress in deciphering the increasingly complex cellular and molecular hematopoietic landscapes in health and disease. This review concludes by highlighting links between chronic inflammation and metabolic and epigenetic changes associated with aging and in the development of clonal hematopoiesis.

Role of CBL Mutations in Cancer and Non-Malignant Phenotype

Simple Summary

CBL mutations are progressively being described as involved in different clinical manifestations. Somatic CBL mutations can be found in different type of cancer. The clinical spectrum of germline mutations configures the so-called CBL syndrome, a cancer-predisposing condition that includes multisystemic involvement characterized by variable phenotypic expression and expressivity. In this review we provide an up-to-date review of the clinical manifestation of CBL mutations and of the molecular mechanisms in which CBL exerts its pathogenic role.

Abstract

CBL plays a key role in different cell pathways, mainly related to cancer onset and progression, hematopoietic development and T cell receptor regulation. Somatic CBL mutations have been reported in a variety of malignancies, ranging from acute myeloid leukemia to lung cancer. Growing evidence have defined the clinical spectrum of germline CBL mutations configuring the so-called CBL syndrome; a cancer-predisposing condition that also includes multisystemic involvement characterized by variable phenotypic expression and expressivity. This review provides a comprehensive overview of the molecular mechanisms in which CBL exerts its function and describes the clinical manifestation of CBL mutations in humans.

Pediatric myelodysplastic syndrome with inflammatory manifestations: Diagnosis, genetics, treatment, and outcome

BACKGROUND

Inflammatory manifestations (IM) are well described in adult patients with myelodysplastic syndrome (MDS), but the presentation is highly variable and no standardized treatment exists. This phenomenon is rarely reported in children. As more pediatric patients are hematopoietic stem cell transplantation (HSCT) candidates, the role of anti-inflammatory treatment in relation to HSCT should be defined.

PROCEDURE

Here, we report a series of five children from a tertiary center. We describe the clinical presentation, molecular findings, and treatment options.

RESULTS

All patients presented with advanced MDS with blast percentages ranging 10-30%, all had severe IM. One patient had MDS secondary to severe congenital neutropenia, the other four patients had presumably primary MDS. All four were found to harbor a PTPN11 gene driver mutation, which is found in 35% of cases of juvenile myelomonocytic leukemia (JMML). The mutation was present in the myeloid lineage but not in T lymphocytes. Three had symptoms of Behcet's-like disease with trisomy 8 in their bone marrow. All patients were treated with anti-inflammatory medications (mainly systemic steroids) in an attempt to bring them to allogeneic HSCT in a better clinical condition. All demonstrated clinical improvement as well as regression in their MDS status post anti-inflammatory treatment. All have recovered from both MDS and their inflammatory symptoms post HSCT.

CONCLUSION

Primary pediatric MDS with IM is driven in some cases by PTPN11 mutations, and might be on the clinical spectrum of JMML. Anti-inflammatory treatment may reverse MDS progression and improve the outcome of subsequent HSCT.

RASopathies: from germline mutations to somatic and multigenic diseases

The RAS-RAF-MEK-ERK signaling pathway is vital for different cellular mechanisms including cell proliferation, differentiation and apoptosis. This importance is highlighted by the high prevalence of mutations in RAS or related proteins of the pathway in cancers. More recently, development abnormalities have been linked to various germline mutations in this pathway and called RASopathies. Interestingly, rare disorders such as RAS-associated leukoproliferative diseases and histiocytosis have also been recently linked to multiple mutations in the same pathway, sometimes with the same mutation. This review will focus on germline RASopathies and rare somatic RASopathies and focus on how gain-of-function mutations in the same pathway can lead to various diseases.

Treatment advances for pediatric and adult onset neoplasms with monocytosis

PURPOSE OF REVIEW

For decades, the management of chronic myelomonocytic leukemia (CMML) or juvenile myelomonocytic leukemia (JMML) has been largely inextricable from myelodysplastic syndromes (MDS), myeloproliferative neoplasms, and acute myeloid leukemia. Hallmarks of these diseases have been the emergence of unique genomic signatures and discouraging responses to available therapies. Here, we will critically examine the current options for management and review the rapidly developing opportunities based on advances in CMML and JMML disease biology.

RECENT FINDINGS

Few clinical trials have exclusively been done in CMML, and in JMML, the rarity of the disease limits wide scale participation. Recent case series in JMML suggest that hypomethylating agents (HMAs) are a viable option for bridging to curative intent with allogeneic hematopoietic stem cell transplant or as posttransplant maintenance. Emerging evidence has demonstrated targeting the RAS-pathway via MEK inhibition may also be considered. In CMML, treatment with HMAs is largely derived from data inclusive of MDS patients, including a small number of patients with dysplastic CMML variants. Based on CMML disease biology, additional therapeutic targets being investigated include inhibitors of splicing, CD123/dendritic cell axis, inherent GM-CSF progenitor cell hypersensitivity, and targeting the JAK/STAT pathway. Current evidence is also expanding for oral HMAs. The management of CMML and JMML is rapidly evolving and clinicians must be aware of the genetic landscape and expanding treatment options to ensure these rare populations are afforded therapeutic interventions best suited to their needs.

Pediatric Neoplasms Presenting with Monocytosis

PURPOSE OF REVIEW

Juvenile myelomonocytic leukemia (JMML) is a rare but severe pediatric neoplasm with hematopoietic stem cell transplant as its only established curative option. The development of targeted therapeutics for JMML is being guided by an understanding of the pathobiology of this condition. Here, we review JMML with an emphasis on genetics in order to (i) demonstrate the relationship between JMML genotype and clinical phenotype and (ii) explore potential genetic targets of novel JMML therapies.

RECENT FINDINGS

DNA hypermethylation studies have demonstrated consistently that methylation is related to disease severity. Increasing understanding of methylation in JMML may open the door to novel therapies, such as DNA methyltransferase inhibitors. The PI3K/AKT/MTOR, JAK/STAT, and RAF/MEK/ERK pathways are being investigated as therapeutic targets for JMML. Future therapy for JMML will be driven by an increased understanding of pathobiology. Targeted therapeutic approaches hold potential for improving outcomes in patients with JMML.

Immunologic evaluation and genetic defects of apoptosis in patients with autoimmune lymphoproliferative syndrome (ALPS)

Apoptosis plays an important role in controlling the adaptive immune response and general homeostasis of the immune cells, and impaired apoptosis in the immune system results in autoimmunity and immune dysregulation. In the last 25 years, inherited human diseases of the Fas-FasL pathway have been recognized. Autoimmune lymphoproliferative syndrome (ALPS) is an inborn error of immunity, characterized clinically by nonmalignant and noninfectious lymphoproliferation, autoimmunity, and increased risk of lymphoma due to a defect in lymphocyte apoptosis. The laboratory hallmarks of ALPS are an elevated percentage of T-cell receptor αβ double negative T cells (DNTs), elevated levels of vitamin B12, soluble FasL, IL-10, IL-18 and IgG, and defective in vitro Fas-mediated apoptosis. In order of frequency, the genetic defects associated with ALPS are germinal and somatic ALPS-FAS, ALPS-FASLG, ALPS-CASP10, ALPS-FADD, and ALPS-CASP8. Partial disease penetrance and severity suggest the combination of germline and somatic FAS mutations as well as other risk factor genes. In this report, we summarize human defects of apoptosis leading to ALPS and defects that are known as ALPS-like syndromes that can be clinically similar to, but are genetically distinct from, ALPS. An efficient genetic and immunological diagnostic approach to patients suspected of having ALPS or ALPS-like syndromes is essential because this enables the establishment of specific therapeutic strategies for improving the prognosis and quality of life of patients.

Clinical Spectrum of Ras-Associated Autoimmune Leukoproliferative Disorder (RALD)

Ras-associated autoimmune leukoproliferative disorder (RALD) is a clinical entity initially identified in patients evaluated for an autoimmune lymphoproliferative syndrome (ALPS)-like phenotype. It remains a matter of debate whether RALD is a chronic and benign lymphoproliferative disorder or a pre-malignant condition. We report the case of a 7-year-old girl diagnosed with RALD due to somatic KRAS mutation who progressed to a juvenile myelomonocytic leukemia phenotype and finally evolved into acute myeloid leukemia. The case report prompted a literature review by a search for all RALD cases published in PubMed and Embase. We identified 27 patients with RALD. The male-to-female ratio was 1:1 and median age at disease onset was 2 years (range 3 months-36 years). Sixteen patients (59%) harbored somatic mutations in KRAS and 11 patients (41%) somatic mutations in NRAS. The most common features were splenomegaly (26/27 patients), autoimmune cytopenia (15/16 patients), monocytosis (18/24 patients), pericarditis (6 patients), and skin involvement (4 patients). Two patients went on to develop a hematopoietic malignancy. In summary, the current case documents an additional warning about the long-term risk of malignancy in RALD.

Elevated basal transcription can underlie timothy channel association with autism related disorders

Timothy syndrome (TS) is a neurodevelopmental disorder caused by mutations in the pore-forming subunit α₁1.2 of the L-type voltage-gated Ca²⁺-channel Cav1.2, at positions G406R or G402S. Although both mutations cause cardiac arrhythmias, only Cav1.2^G406R is associated with the autism-spectrum-disorder (ASD). We show that transcriptional activation by Cav1.2^G406R and Cav1.2^G402S is driven by membrane depolarization through the Ras/ERK/CREB pathway in a process called excitation-transcription (ET) coupling, as previously shown for wt Cav1.2. This process requires the presence of the intracellular β-subunit of the channel. We found that only the autism-associated mutant Cav1.2^G406R, as opposed to the non-autistic mutated channel Cav1.2^G402S, exhibits a depolarization-independent CREB phosphorylation, and spontaneous transcription of cFos and MeCP2. A leftward voltage-shift typical of Cav1.2^G406R activation, increases channel opening at subthreshold potentials, resulting in an enhanced channel activity, as opposed to a rightward shift in Cav1.2^G402S. We suggest that the enhanced spontaneous Cav1.2^G406R activity accounts for the increase in basal transcriptional activation. This uncontroled transcriptional activation may result in the manifestation of long-term dysregulations such as autism. Thus, gating changes provide a mechanistic framework for understanding the molecular events underlying the autistic phenomena caused by the G406R Timothy mutation. They might clarify whether a constitutive transcriptional activation accompanies other VGCC that exhibit a leftward voltage-shift of activation and are also associated with long-term cognitive disorders.