Juvenile Myelomonocytic Leukemia

Autoinflammation in patients with leukocytic CBL loss of heterozygosity is caused by constitutive ERK-mediated monocyte activation

Patients heterozygous for germline CBL loss-of-function (LOF) variants can develop myeloid malignancy, autoinflammation, or both, if some or all of their leukocytes become homozygous for these variants through somatic loss of heterozygosity (LOH) via uniparental isodisomy. We observed an upregulation of the inflammatory gene expression signature in whole blood from these patients, mimicking monogenic inborn errors underlying autoinflammation. Remarkably, these patients had constitutively activated monocytes that secreted 10 to 100 times more inflammatory cytokines than those of healthy individuals and CBL LOF heterozygotes without LOH. CBL-LOH hematopoietic stem and progenitor cells (HSPCs) outgrew the other cells, accounting for the persistence of peripheral monocytes homozygous for the CBL LOF variant. ERK pathway activation was required for the excessive production of cytokines by both resting and stimulated CBL-LOF monocytes, as shown in monocytic cell lines. Finally, we found that about 1 in 10,000 individuals in the UK Biobank were heterozygous for CBL LOF variants and that these carriers were at high risk of hematological and inflammatory conditions.

Clinical parameter-based prediction of DNA methylation classification generates a prediction model of prognosis in patients with juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare heterogeneous hematological malignancy of early childhood characterized by causative RAS pathway mutations. Classifying patients with JMML using global DNA methylation profiles is useful for risk stratification. We implemented machine learning algorithms (decision tree, support vector machine, and naïve Bayes) to produce a DNA methylation-based classification according to recent international consensus definitions using a well-characterized pooled cohort of patients with JMML (n = 128). DNA methylation was originally categorized into three subgroups: high methylation (HM), intermediate methylation (IM), and low methylation (LM), which is a trichotomized classification. We also dichotomized the subgroups as HM/IM and LM. The decision tree model showed high concordances with 450k-based methylation [82.3% (106/128) for the dichotomized and 83.6% (107/128) for the trichotomized subgroups, respectively]. With an independent cohort (n = 72), we confirmed that these models using both the dichotomized and trichotomized classifications were highly predictive of survival. Our study demonstrates that machine learning algorithms can generate clinical parameter-based models that predict the survival outcomes of patients with JMML and high accuracy. These models enabled us to rapidly and effectively identify candidates for augmented treatment following diagnosis.

Chronic myeloid leukemia: a type of MPN

This review article classifies chronic myeloid leukemia (CML) based on cytogenetic analyses and different mutations detected in CML patients. The use of advanced technologies, such as karyotyping, fluorescent in situ hybridization, and comparative genomic hybridization, has allowed us to study CML in detail and observe the different biochemical changes that occur in different CML types. This review also highlights the different types of receptor and signaling pathway mutations that occur in CML.

Immunophenotypic changes in juvenile myelomonocytic leukaemia after treatment with hypomethylating agent: Do they help to evaluate dept of response?

5-Azacitidine has been used before stem cell transplantation in juvenile myelomonocytic leukaemia (JMML) patients. Recently, we have described immunophenotypic features in JMML at diagnosis. Here, our aim was to examine the changes in the immunophenotypic features during azacitidine treatment, correlating it with clinical response. Patients treated with 5-azacitidine were evaluated at diagnosis and after three and six cycles of medication. Among 32 patients entering the study, 28 patients were examined after three cycles and 25 patients after six. Patients showed a reduction in CD34/CD117⁺ cells: median 3.35% at diagnosis, 2.8% after three cycles and 1.63% after six. B-cell progenitors were decreased at diagnosis and decreased after treatment. Monocytes decreased: 11.91% to 6.4% and 4.18% respectively. Complete response was associated with increase in classical monocytes. T lymphocytes, reduced at diagnosis, increased in patients responding to 5-azacitidine. Immunophenotypic aberrancies including expression of CD7 in myeloid progenitors remained after treatment. This feature was associated with a worse response to treatment, as well as presence of NF1. Immunophenotyping was feasible in all patients. Clinical response was associated with a decrease of myeloid progenitors and monocytes and a rise in T lymphocytes although phenotypic aberrancies persisted. The largest effect was observed after three cycles.

Juvenile myelomonocytic leukemia in the molecular era: a clinician's guide to diagnosis, risk stratification, and treatment

Juvenile myelomonocytic leukemia is an overlapping myeloproliferative and myelodysplastic disorder of early childhood . It is associated with a spectrum of diverse outcomes ranging from spontaneous resolution in rare patients to transformation to acute myeloid leukemia in others that is generally fatal. This unpredictable clinical course, along with initially descriptive diagnostic criteria, led to decades of productive international research. Next-generation sequencing now permits more accurate molecular diagnoses in nearly all patients. However, curative treatment is still reliant on allogeneic hematopoietic cell transplantation for most patients, and additional advances will be required to improve risk stratification algorithms that distinguish those that can be observed expectantly from others who require swift hematopoietic cell transplantation.

A retrospective analysis of azacitidine treatment for juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a pediatric hematological malignancy with a poor prognosis. Although several case series have been published describing hematological and molecular responses to azacitidine (AZA) treatment in patients with JMML, the efficacy and safety profile of AZA is not well investigated, especially in Asian children and children undergoing hematopoietic stem cell transplantation (HSCT). We retrospectively analyzed 5 patients who received a total of 12 cycles (median 2 cycles) of AZA treatment in Japan. All five patients were boys and their ages at the time of treatment were 21, 23, 24, 26, and 46 months, respectively. All five patients tolerated AZA treatment, including four patients who received AZA after HSCT. Therapeutic toxicity with AZA was mostly limited to hematological toxicity. The only serious non-hematological adverse event was hyperbilirubinemia (grades III-IV) observed in a patient who received AZA after a second HSCT. Two out of five patients treated with AZA achieved a partial response (PR), while three patients treated for post-transplant relapse did not have an objective response. Future prospective studies should be conducted to develop combination therapies with AZA and other molecular targeted drugs for high-risk patients.

Advances in germline predisposition to acute leukaemias and myeloid neoplasms

Although much work has focused on the elucidation of somatic alterations that drive the development of acute leukaemias and other haematopoietic diseases, it has become increasingly recognized that germline mutations are common in many of these neoplasms. In this Review, we highlight the different genetic pathways impacted by germline mutations that can ultimately lead to the development of familial and sporadic haematological malignancies, including acute lymphoblastic leukaemia, acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS). Many of the genes disrupted by somatic mutations in these diseases (for example, TP53, RUNX1, IKZF1 and ETV6) are the same as those that harbour germline mutations in children and adolescents who develop these malignancies. Moreover, the presumption that familial leukaemias only present in childhood is no longer true, in large part due to the numerous studies demonstrating germline DDX41 mutations in adults with MDS and AML. Lastly, we highlight how different cooperating events can influence the ultimate phenotype in these different familial leukaemia syndromes.

Outcomes of juvenile myelomonocytic leukemia patients after sequential therapy with cytarabine and 6-mercaptopurine

Juvenile myelomonocytic leukemia(JMML) is a pediatric myeloproliferative disorder. Allogeneic hematopoietic stem cell transplant (HSCT) is the only curative treatment for JMML. Pre-transplant therapy is a matter of controversy, and there are no firm recommendations. Whether chemotherapy is effective in achieving durable remission is questionable. Patients diagnosed as JMML at our center from January-2014 to December-2019 were retrospectively analyzed. All patients treated with at least one cycle of sequential therapy with subcutaneous cytarabine and oral 6-mercaptopurine were further assessed. The total number of patients diagnosed during the study period was 33. Patients were divided into two groups: patients who did not get any chemotherapy (n = 13) and ones who received at least one cycle of chemotherapy(n = 20). Age, total leukocyte count (TLC), monocyte percent, platelet count and spleen size were comparable between the two groups. There was no difference in the overall survival between the two groups, but 6 out of 20 patients showed a response to chemotherapy (2 complete remission, 4 partial remission). Two patients out of 20 underwent hematopoietic stem cell transplant (HSCT). The patients who achieved complete remission received 12 cycles of chemotherapy and have been in follow up for 28 months and 50 months respectively. Our results showed that sequential therapy with 6-mercaptopurine and cytarabine may be offered to patients in whom HSCT is not feasible or as a bridge therapy in those awaiting HSCT. The advantages of this approach include low cost, out-patient management and decreased requirement of blood components. In a subset of patients it may achieve remission.

CIN or not: An approach to the evaluation and management of chronic idiopathic neutrophilia

Neutrophilia refers to an increase in the number of circulating neutrophils in the peripheral blood. Some common etiologies include infection, inflammatory conditions, myeloproliferative disorders, malignancies, endocrinopathies, drugs, and anemia. Rare disorders such as leukocyte adhesion deficiency can also cause neutrophilia. In many cases, there is an elevation of neutrophil count that persists for months or even years with no clear underlying cause in an otherwise asymptomatic patient. This is referred to as chronic idiopathic neutrophilia (CIN). Despite being a condition encountered by many physicians, there is a paucity of literature addressing CIN. Certain conditions such as stress, exercise, smoking, obesity, and obstructive sleep apnea have been associated with CIN and may provide explanations for neutrophilia previously thought to be idiopathic. Herein, we present a review of the literature on CIN and propose a systematic approach to this commonly encountered clinical condition.

RAS Pathway Mutation Patterns in Patients With Juvenile Myelomonocytic Leukemia: A Developing Country Single-center Experience

INTRODUCTION

Juvenile myelomonocytic leukemia (JMML) is a rare clonal myelodysplastic/myeloproliferative neoplasm of early childhood. Historically, it was difficult to diagnose clinically, as patients present with manifestations shared with other hematologic malignancies or viral infections. It is now clear that JMML is a disease of hyperactive RAS signaling.

PATIENTS AND METHODS

We examined the bone marrow of 41 Egyptian children with JMML by direct sequencing for mutations in the RAS pathway genes.

RESULTS

Mutations were detected in 33 (80%) of 41 patients. We identified 12 (29%) of 41 patients with PTPN11 mutation; 18 (44%) of 41 with RAS mutation; 9 (22%) of 41 with NRAS mutation; 9 (22%) of 41 with KRAS mutation; and 3 (7%) of 41 with CBL mutation. Eleven (92%) of the PTPN11 mutations were detected in exon 3 and 1 (8%) in exon 13. Seven of the NRAS mutations were in exon 2, and 2 were in exon 3. All KRAS mutations were in exon 2. The 3 cases with CBL mutation were homozygous mutations in exon 8. All the mutations detected in PTPN11, NRAS/KRAS, and the CBL genes were previously reported missense mutations in JMML.

CONCLUSION

Our results demonstrate that Egyptian children diagnosed with JMML have high frequency of NRAS/KRAS mutations and lower frequency of PTPN11 mutations as compared with previous studies. The concept of mutually exclusive RAS pathway mutations was clearly observed in our patients. All cancer centers in our region should start implementing molecular diagnostic methods before confirming the diagnosis of JMML and before offering hematopoietic stem cell transplantation.

After 95 years, it's time to eRASe JMML

Juvenile myelomonocytic leukaemia (JMML) is a rare clonal disorder of early childhood. Constitutive activation of the RAS pathway is the initial event in JMML. Around 90% of patients diagnosed with JMML carry a mutation in the PTPN11, NRAS, KRAS, NF1 or CBL genes. It has been demonstrated that after this first genetic event, an additional somatic mutation or epigenetic modification is involved in disease progression. The available genetic and clinical data have enabled researchers to establish relationships between JMML and several clinical conditions, including Noonan syndrome, Ras-associated lymphoproliferative disease, and Moyamoya disease. Despite scientific progress and the development of more effective treatments, JMML is still a deadly disease: the 5-year survival rate is ~50%. Here, we report on recent research having led to a better understanding of the genetic and molecular mechanisms involved in JMML.

Proteomic Analysis of an Induced Pluripotent Stem Cell Model Reveals Strategies to Treat Juvenile Myelomonocytic Leukemia

Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative neoplasm of early childhood with a poor survival rate, thus there is a requirement for improved treatment strategies. Induced pluripotent stem cells offer the ability to model disease and develop new treatment strategies. JMML is frequently associated with mutations in PTPN11. Children with Noonan syndrome, a development disorder, have an increased incidence of JMML associated with specific germline mutations in PTPN11. We undertook a proteomic assessment of myeloid cells derived from induced pluripotent stem cells obtained from Noonan syndrome patients with PTPN11 mutations, either associated or not associated with an increased incidence of JMML. We report that the proteomic perturbations induced by the leukemia-associated PTPN11 mutations are associated with TP53 and NF-Kκb signaling. We have previously shown that MYC is involved in the differential gene expression observed in Noonan syndrome patients associated with an increased incidence of JMML. Thus, we employed drugs to target these pathways and demonstrate differential effects on clonogenic hematopoietic cells derived from Noonan syndrome patients, who develop JMML and those who do not. Further, we demonstrated these small molecular inhibitors, JQ1 and CBL0137, preferentially extinguish primitive hematopoietic cells from sporadic JMML patients as opposed to cells from healthy individuals.

Disease burden and conditioning regimens in ASCT1221, a randomized phase II trial in children with juvenile myelomonocytic leukemia: A Children's Oncology Group study

BACKGROUND

Most patients with juvenile myelomonocytic leukemia (JMML) are curable only with allogeneic hematopoietic cell transplantation (HCT). However, the current standard conditioning regimen, busulfan-cyclophosphamide-melphalan (Bu-Cy-Mel), may be associated with higher risks of morbidity and mortality. ASCT1221 was designed to test whether the potentially less-toxic myeloablative conditioning regimen containing busulfan-fludarabine (Bu-Flu) would be associated with equivalent outcomes.

PROCEDURE

Twenty-seven patients were enrolled on ASCT1221 from 2013 to 2015. Pre- and post-HCT (starting Day +30) mutant allele burden was measured in all and pre-HCT therapy was administered according to physician discretion.

RESULTS

Fifteen patients were randomized (six to Bu-Cy-Mel and nine to Bu-Flu) after meeting diagnostic criteria for JMML. Pre-HCT low-dose chemotherapy did not appear to reduce pre-HCT disease burden. Two patients, however, received aggressive chemotherapy pre-HCT and achieved low disease-burden state; both are long-term survivors. All four patients with detectable mutant allele burden at Day +30 post-HCT eventually progressed compared to two of nine patients with unmeasurable allele burden (P = 0.04). The 18-month event-free survival of the entire cohort was 47% (95% CI, 21-69%), and was 83% (95% CI, 27-97%) and 22% (95% CI, 03-51%) for Bu-Cy-Mel and Bu-Flu, respectively (P = 0.04). ASCT1221 was terminated early due to concerns that the Bu-Flu arm had inferior outcomes.

CONCLUSIONS

The regimen of Bu-Flu is inadequate to provide disease control in patients with JMML who present to HCT with large burdens of disease. Advances in molecular testing may allow better characterization of biologic risk, pre-HCT responses to chemotherapy, and post-HCT management.

Use of Rapamycin in a Patient With Juvenile Myelomonocytic Leukemia: A Case Report

The relapse rate for children with juvenile myelomonocytic leukemia (JMML) status post hematopoietic stem cell transplantation (HSCT) approaches 50% within 5 years. Graft-versus-leukemia (GVL) is thought to play important role in the treatment of JMML. For this reason, careful management of immunosuppressive drugs after HSCT is crucial. This case report demonstrates that rapamycin and GVL represent a viable medical strategy for the management of pediatric patients with JMML who relapse following status post-HSCT.

Association Between Juvenile Myelomonocytic Leukemia, Juvenile Xanthogranulomas and Neurofibromatosis Type 1: Case Report and Review of the Literature

The occurrence of juvenile myelomonocytic leukemia (JMML), juvenile xanthogranuloma (JXG), and neurofibromatosis type 1 (NF1) together is relatively rare. Approximately only 20 cases have been reported in the literature. It is debated whether children with NF1 and JXG are at higher risk of developing JMML than children with NF1 alone. We present the case of a boy primarily diagnosed with NF1 with coexisting JXG who developed JMML at the age of 22 months. The clinical course from initial presentation to final diagnosis is detailed and the genetic features and hematologic characteristics are discussed. We report this case to underscore the importance of close monitoring of blood count and strict clinical follow-up in children presenting with concurrent NF1 and JXG and provide a possible explanation for this association.

Juvenile myelomonocytic leukemia presenting as bilateral breast masses

An 8-year-old girl presented with bilateral breast masses and was subsequently diagnosed with juvenile myelomonocytic leukemia. Juvenile myelomonocytic leukemia is a rare myelodysplastic syndrome that typically presents in boys younger than 3 years of age with splenomegaly, lymphadenopathy and skin findings. Bilateral breast masses in a child are rare and, as such, present a diagnostic dilemma due to the relative paucity of cases in the literature. We present a case of granulocytic sarcoma of the breasts in a patient with juvenile myelomonocytic leukemia. The authors hope that increased reporting and research regarding pediatric breast masses will help create awareness for such cases.

Diagnosis and treatment of juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic/myeloproliferative disorder that occurs during infancy and early childhood; this disorder is characterized by hypersensitivity of the myeloid progenitor cells to granulocyte-macrophage colony-stimulating factor in vitro. JMML usually involves somatic and/or germline mutations in the genes of the RAS pathway, including PTPN11, NRAS, KRAS, NF1, and CBL, in the leukemic cells. Almost all patients with JMML experience an aggressive clinical course, and hematopoietic stem cell transplantation (HSCT) is the only curative treatment. A certain proportion of patients with somatic NRAS and germline mutations in CBL, however, have spontaneous resolution. A suitable treatment after diagnosis and conditioning regimen prior to HSCT are yet to be determined, but several clinical trials have been initiated throughout the world to develop suitable pre- or post-allogeneic HSCT treatments and new targeted therapies that are less toxic, to improve patient outcome.

Juvenile Myelomonocytic Leukemia in a Premature Neonate Mimicking Neonatal Sepsis

Juvenile myelomonocytic leukemia (JMML) is a rare hematologic malignancy in children. Its presentations include anemia, thrombocytopenia, monocytosis, skin rash, marked hepatomegaly, and/or splenomegaly. Fever and respiratory involvement are common. Here, we report a case of a premature neonate with initial symptoms of respiratory distress. She gradually developed clinical manifestations of JMML that mimicked neonatal sepsis. Three weeks after birth, JMML was diagnosed. This is the first reported case of JMML presenting in a premature infant in Taiwan.

How I treat juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a unique, aggressive hematopoietic disorder of infancy/early childhood caused by excessive proliferation of cells of monocytic and granulocytic lineages. Approximately 90% of patients carry either somatic or germline mutations of PTPN-11, K-RAS, N-RAS, CBL, or NF1 in their leukemic cells. These genetic aberrations are largely mutually exclusive and activate the Ras/mitogen-activated protein kinase pathway. Allogeneic hematopoietic stem cell transplantation (HSCT) remains the therapy of choice for most patients with JMML, curing more than 50% of affected children. We recommend that this option be promptly offered to any child with PTPN-11-, K-RAS-, or NF1-mutated JMML and to the majority of those with N-RAS mutations. Because children with CBL mutations and few of those with N-RAS mutations may have spontaneous resolution of hematologic abnormalities, the decision to proceed to transplantation in these patients must be weighed carefully. Disease recurrence remains the main cause of treatment failure after HSCT. A second allograft is recommended if overt JMML relapse occurs after transplantation. Recently, azacytidine, a hypomethylating agent, was reported to induce hematologic/molecular remissions in some children with JMML, and its role in both reducing leukemia burden before HSCT and in nontransplant settings requires further studies.

Juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML), a rare myeloid malignancy that occurs in young children, is considered a clonal disease originating in pluripotent stem cells of the hematopoietic system. The pathogenesis of JMML involves disruption of signal transduction through the RAS pathway, with resultant selective hypersensitivity of JMML cells to granulocyte-macrophage colony-stimulating factor. Progress has been made in understanding aspects of the molecular basis of JMML. How these molecular mechanisms may lead to targeted therapeutics and improved outcomes remains to be elucidated. Allogeneic hematopoietic stem cell transplant is the only curative option for children with JMML, and it is fraught with frequent relapse and significant toxicity.

Stem cell transplant for juvenile myelomonocytic leukemia and chronic myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) and chronic myelomonocytic leukemia (CMML) are myelodysplastic/myeloproliferative neoplasms associated with poor prognosis. There is no definitive treatment for such patients other than stem cell transplantation, and chemotherapy is not much effective. Timely diagnosis and early referral to the transplant centre is important for the management of these diseases. We report here a case of JMML and another case of CMML who were treated successfully with peripheral blood stem cell transplantation.

Juvenile myelomonocytic leukemia in India: cure remains a distant dream!

There is paucity of outcome data regarding juvenile myelomonocytic leukemia from India. We report a series of eight children. Three had monosomy 7 and one had complex cytogenetics. One with Down's syndrome recovered spontaneously. Three refused therapy of whom only one is alive with disease. One died post chemotherapy. Three underwent allogeneic stem cell transplant after protracted delay with funds arranged from various governmental and non-governmental organizations. Of these two died (relapse-1 and intracranial bleed-1) and one is alive and disease free. In India, it's a milestone to reach transplant due to high cost and cure still remains a distant dream.

Control of thrombotic thrombocytopenic purpura by sirolimus in a child with juvenile myelomonocytic leukemia and somatic N-RAS mutation

We describe an infant who developed juvenile myelomonocytic leukemia (JMML) at the age of 6 months. Myeloproliferation was effectively controlled by low-dose cytosine arabinoside and 13-cis retinoic acid therapy. Two years after therapy for JMML was stopped, at the age of 5 years, the patient developed autoimmune thrombotic thrombocytopenic purpura (TTP). TTP was transiently controlled by plasma exchange, prednisolone, rituximab, and cyclophosphamide, but relapsed within a short time. Long-term control of TTP was established by sirolimus. Somatic N-RAS G38A→Gly13Asp substitution was restricted to hematopoietic cells. The somatic N-RAS mutation may link myeloproliferation and autoimmunity.

Cytogenetics and clinical features of pediatric myelodysplastic syndrome in Japan

We analyzed the cytogenetics and clinical features of pediatric myelodysplastic syndrome (MDS) in Japan. Data on patients (<16 years) diagnosed with MDS from 1990 to 2000 were retrospectively collected from pediatric hematologists in 234 institutions. Chromosome analysis was successfully performed in 255 of 277 MDS patients. The numbers of patients with refractory anemia, refractory anemia with ringed sideroblasts, refractory anemia with excess of blasts (RAEB), refractory anemia with excess of blasts in transformation (RAEBt), chronic myelomonocytic leukemia, and juvenile myelomonocytic leukemia were 67 (24%), 51 (18%), 51 (18%), 20 (7%), and 65 (23%), respectively. The other 23 patients (8%) could not be classified specifically. The distribution of childhood MDS in Japan according to the French-American-British subclassification was similar to that in other countries. However, we identified a higher incidence of therapy-related cases. As for relationship between cytogenetics and prognoses, abnormal karyotypes were related to poorer prognoses than normal karyotype (P < 0.01). However, patients with trisomy 8 had prognoses comparable to those with normal karyotypes. Complex karyotypes were associated with poorer prognoses among RAEB and RAEBt patients. In conclusion, prognosis of pediatric MDS is related to cytogenetics. A more precise diagnosis and classification system is needed for childhood MDS.

Translational hematology

Translational research is scientific research that helps to make findings from basic science useful for practical applications in the clinic. The successful use of a drug that interferes with the specific molecular pathophysiology of cancer remains the ultimate vision in cancer medicine. Translational research is a multistep process including the discovery of a cytogenetic/molecular aberration as well as the demonstration of its pathophysiological relevance and its druggability by in vitro experiments and in vivo animal models. Information obtained from preclinical research paves the way for clinical trials in which a drug of interest is developed until its clinical application. Modern pathophysiology-oriented anticancer drugs that have been developed by translational research are available for clinical applications since the beginning of this millennium. By using these drugs higher efficacy and lower toxicity could be achieved as compared with previous treatments. In this article, we will present some of the most prominent examples of this translational approach.

Bedside to bench in juvenile myelomonocytic leukemia: insights into leukemogenesis from a rare pediatric leukemia

Juvenile myelomonocytic leukemia (JMML) is a typically aggressive myeloid neoplasm of childhood that is clinically characterized by overproduction of monocytic cells that can infiltrate organs, including the spleen, liver, gastrointestinal tract, and lung. JMML is categorized as an overlap myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) by the World Health Organization and also shares some clinical and molecular features with chronic myelomonocytic leukemia, a similar disease in adults. Although the current standard of care for patients with JMML relies on allogeneic hematopoietic stem cell transplant, relapse is the most frequent cause of treatment failure. Tremendous progress has been made in defining the genomic landscape of JMML. Insights from cancer predisposition syndromes have led to the discovery of nearly 90% of driver mutations in JMML, all of which thus far converge on the Ras signaling pathway. This has improved our ability to accurately diagnose patients, develop molecular markers to measure disease burden, and choose therapeutic agents to test in clinical trials. This review emphasizes recent advances in the field, including mapping of the genomic and epigenome landscape, insights from new and existing disease models, targeted therapeutics, and future directions.

Cytosine arabinoside and mitoxantrone followed by second allogeneic transplant for the treatment of children with refractory juvenile myelomonocytic leukemia

Hematopoietic stem cell transplantation (HSCT) remains the only curative option for most patients with juvenile myelomonocytic leukemia (JMML). However, persistent disease and relapse rates after transplant range from 26% to 58%. We report the successful use of second HSCT after preparation with mitoxantrone and cytosine arabinoside (Ara-C) for patients with refractory or recurrent disease. Between 1993 and 2006, 5 children who underwent HSCT at our institution as initial therapy for JMML had persistent disease or relapsed. Pre-HSCT conditioning varied and donors were either HLA-matched siblings (n=2) or matched unrelated donors (n=3). After initial HSCT, they subsequently received high-dose Ara-C (3 g/m IV) every 12 hours on days -8 through -3 and mitoxantrone (10 mg/m/d IV) on days -8, -7, -6 followed by second HSCT from their original donors. All 5 patients are alive at 88, 179, 199, 234, and 246 months with no evidence of JMML, no significant toxicity, and 100% donor chimera as determined by PCR short-tandem repeat analysis. Our experience supports second transplant utilizing high-dose Ara-C and mitoxantrone in children with JMML who do not respond or relapse after first transplant.

Skin Infiltration of Juvenile Myelomonocytic Leukemia

We described a two-year-old boy who developed a skin infiltration from JMML. Several indurated erythematous lesions were seen on his back on his first visit to our department. Edematous erythemas had repeatedly appeared on his auricles and feet for the previous six months. He had had a high fever for a month. Hepatosplenomegaly and superficial lymphadenopathy were recognized. Laboratory investigation showed leukocytosis and anemia. The diagnosis of JMML was confirmed by the findings of myeloid hyperplasia in his bone marrow and the spontaneous colony formation and GM-CSF hypersensitivity in a culture of bone marrow cells. Histopathologically, large atypical mononuclear cells were infiltrated throughout the dermis in a perivascular and interstitial distribution in a skin biopsy specimen. These cells were CD3 (-), CD20 (-), CD45 (+), CD68 (+) and myeloperoxidase (+). Bone marrow transplantation and then cord blood stem cell transplantation were performed but soon rejected. The indurated erythematous lesions appeared again soon after the relapse of JMML. There are other reported cases of JMML with skin infiltration that preceded any other manifestations of the disease. JMML cells in some patients, including our case, seem to have a great affinity for the skin, and skin biopsy aids in early detection of this disease.

Histologic findings in skin biopsy in a JMML rash: a case report and review of literature

Juvenile myelomonocytic leukemia (JMML), belonging to the category of myeloproliferative/myelodysplastic syndromes, is a rare pediatric hematologic malignancy with frequent skin manifestations commonly in the form of rashes. However, these rashes are not always biopsied and their immunophenotype studied in details. We report one such case in a 2-year-old boy who presented with a 1-month history of nonresolving fever, fatigue, and pallor along with a generalized maculopapular skin rash. The child also had mild hepatomegaly. A complete blood count with differential revealed a hemoglobin value of 8.6 g/L, leukocytosis (white blood cell count of 55.3 × 109/L), absolute monocytosis (27 × 109/L), immature granulocytes, and a platelet count of 126 × 109/L. The bone marrow aspirate showed a hypercellular marrow with trilineage hematopoiesis, 10% blasts (including promonocytes), increased monocytes (46%), and dysplastic changes in the erythroid and myeloid cell lines. These findings along with absence of a BCR-ABL1 fusion gene and a hemoglobin F level of 3.4% were consistent with the diagnosis of JMML, which was confirmed by subsequent positive granulocyte macrophage-colony stimulating factor hypersensitivity and NRAS mutation studies. A skin biopsy of the rash revealed a dermal infiltrate composed predominantly of atypical monocytic cells that were positive for CD68, myeloperoxidase, and lysozyme and negative for CD117, CD1a, and S100, consistent with JMML.

Juvenile myelomonocytic leukemia: molecular pathogenesis informs current approaches to therapy and hematopoietic cell transplantation

Juvenile myelomonocytic leukemia (JMML) is a rare childhood leukemia that has historically been very difficult to confidently diagnose and treat. The majority of patients ultimately require allogeneic hematopoietic cell transplantation (HCT) for cure. Recent advances in the understanding of the pathogenesis of the disease now permit over 90% of patients to be molecularly characterized. Pre-HCT management of patients with JMML is currently symptom-driven. However, evaluation of potential high-risk clinical and molecular features will determine which patients could benefit from pre-HCT chemotherapy and/or local control of splenic disease. Furthermore, new techniques to quantify minimal residual disease burden will determine whether pre-HCT response to chemotherapy is beneficial for long-term disease-free survival. The optimal approach to HCT for JMML is unclear, with high relapse rates regardless of conditioning intensity. An ongoing clinical trial in the Children's Oncology Group will test if less toxic approaches can be equally effective, thereby shifting the focus to post-HCT immunomanipulation strategies to achieve long-term disease control. Finally, our unraveling of the molecular basis of JMML is beginning to identify possible targets for selective therapeutic interventions, either pre- or post-HCT, an approach which may ultimately provide the best opportunity to improve outcomes for this aggressive disease.

Validation of flow cytometric phospho-STAT5 as a diagnostic tool for juvenile myelomonocytic leukemia

To diagnose juvenile myelomonocytic leukemia (JMML) is sometimes challenging, because around 10% of patients lack molecular abnormalities affecting Ras-MAPK (mitogen-activated protein kinase) pathway and other diseases such as cytomegalovirus infection can mimic clinical signs of JMML. In order to validate a phospho-specific flow cytometry assay assessing phospho-signal transducer and activator of transcription factor 5 (p-STAT5) as a new diagnostic tool for JMML, we examined 22 samples from children with JMML and 47 controls. CD33+/CD34+ cells from 22 patients with JMML showed hyperphosphorylation of STAT5 induced by sub-saturating doses of granulocyte-macrophage colony-stimulating factor (GM-CSF). Using a training set of samples (11 JMML and 23 controls), we identified a threshold for p-STAT5-positive after stimulation with 0.1 ng/ml GM-CSF (17.17%) that discriminates JMML from controls. This threshold was validated in an independent series (11 JMML, 24 controls and 7 cases with diseases other than JMML) where we demonstrated that patients with JMML could be distinguished from other subjects with a sensitivity of 91% (confidence interval (CI) 59–100%) and a specificity of 87% (CI 70–96%). Positive and negative predictive values were 71% (CI 42–92%) and 96% (CI 82–100%), respectively. In conclusion, flow cytometric p-STAT5 profiling is a reliable diagnostic tool for identifying patients with JMML and can contribute to consistency of current diagnostic criteria.

Review of therapeutic options and the management of patients with myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a poorly understood group of disorders caused by one or more genetic aberrations in the bone marrow-derived cell line responsible for hematopoiesis. Recent advances in genetic medicine have offered new insights into the epigenesis as well as the prognosis of MDS, but have not resulted in new or improved curative treatment options. Bone marrow transplantation, introduced before the advent of genetic medicine, is still the only potential cure. Advances in other medical and pharmaceutical areas have broadened the scope of supportive care and disease-modifying therapies, and treating physicians now have a broad range of disease management options depending on a patient's likely prognosis. There is now clear evidence that appropriate supportive care and therapeutic intervention can improve progression-free and overall survival of MDS patients.

Juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare fatal hematopoietic disorder of early childhood. We are presenting a case of 9-month-old female child who was admitted with abdominal distension, irritability, and hepatosplenomegaly. Peripheral blood film examination showed leukoerythroblastosis with leukocytosis, absolute monocytosis, microcytic hypo chromic anemia, and thrombocytopenia. Bone marrow examination showed myeloid hyperplasia, Hb HPLC revealed normal HbF (1.3 %) and HbA2 (2.9 %). There was absolute gamma globulinemia and DCT positivity. Cytogenetic studies revealed a normal karyotype with absence of Philadelphia (Ph) chromosome, monosomy 7 or any other chromosomal abnormality. Diagnosis of JMML was rendered according to the diagnostic criteria laid down by WHO classification 2008 with presence of peripheral blood monocytosis >1 × 10(9)/L, blasts <20 % of leucocytes in blood or nucleated cells in bone marrow, absence of Ph chromosome, presence of immature granulocytes in the blood and WBC count >10 × 10(9)/L. The patient was then started on a regimen of chemotherapy to which she gave a promising response.

Unusual blasts with basophilic granules in 2 cases of de novo acute myeloid leukemia with inv3(q21q26.2) and monosomy 7 and coexpression of CD2 and CD31

Acute myeloid leukemia with inv3(q21q26.2)/t(3,3)(q21;q26.2) is a subtype of acute myeloid leukemia associated with significant dysmyelopoiesis and a poor prognosis. In more than a half of the cases, there is also monosomy 7. We present 2 young male patients with de novo acute myeloid leukemia with inversion 3 and monosomy 7 who had significant morphologic and immunophenotypical similarities. Both patients had circulating subsets of blasts with unusual intracytoplasmic basophilic granules and prominent bone marrow dysmegakaryopoiesis. The leukemic myeloid blasts were negative for myeloperoxidase and had aberrant coexpression of CD2 and CD31. Despite their morphologic and immunophenotypical similarities, only 1 of the patients achieved remission and remained free of disease 24 months after bone marrow transplant. The younger patient, who had also increased hemoglobin F and an associated FLT3 D835 variant, had an acute myeloid leukemia refractory to chemotherapy and died 4 months after his diagnosis.

Outcomes of immunological interventions for mixed chimerism following allogeneic stem cell transplantation in children with juvenile myelomonocytic leukemia

BACKGROUND

For children with juvenile myelomonocytic leukemia (JMML) who undergo stem cell transplantation (SCT), the role of immunological interventions including withdrawal of immunosuppressive therapy (IST) and donor lymphocyte infusion (DLI) for treatment of disease recurrence remains uncertain.

PROCEDURE

We analyzed serial chimerism status following SCT and evaluated the efficacy of immunological interventions for the management of mixed chimerism (MC) in children with JMML.

RESULTS

Chimerism analysis was available in 26 SCT cases following the first and second SCT. MC was observed in 16 cases and withdrawal of IST was performed in 14 cases immediately after identification of MC. Donor lymphocyte infusion (DLI) was performed in five MC cases. Eight MC cases were observed at the time of neutrophil recovery. Following withdrawal of IST, three cases achieved complete chimerism (CC) while the proportion of autologous cells increased rapidly in the remaining five cases. Six MC cases were observed after achievement of hematological remission (HR) and responses to withdrawal of IST were observed in two cases. In the remaining four cases, despite withdrawal of IST, the proportion of autologous cells increased. Five cases received DLI but only one case responded.

CONCLUSION

Although the benefits of immunological interventions for MC after SCT in JMML were limited, some patients did achieve HR as a result of these treatment modalities without a second SCT. Close monitoring of donor chimerism and early detection of MC is helpful in guiding treatment after SCT in children with JMML.

False positive result of the direct antiglobulin test (DAT): the role of the elevated level of immunoglobulin G

Direct antiglobulin test (DAT) is a test that shows antibodies bound to the surface antigens of erythrocytes. In this article, our aim was to investigate whether a correlation exists between a DAT positive test and serum immunoglobulin (Ig) levels. In our clinic, all DAT positive patients were retrospectively studied. Patients who had not received a blood transfusion within the last three months and who were evaluated for Ig levels were enrolled in the study (n = 15). Of these subjects, 15 showed a DAT positive result. Ten patients did not show any clinical or laboratory signs of hemolysis, while five patients exhibited signs and symptoms of autoimmune hemolytic anemia (AIHA). While all subjects showed a DAT positive test result (Ig G ± C(3)), four patients without AIHA, and three patients with AIHA showed a positive indirect antiglobulin test (IAT). In patients with a higher level of immunoglobulin G (IgG), the treatment of the concomitant disease resulted in normalization of the IgG level and led to a negative DAT test. The conditions that lead to an elevation of Ig should be reviewed in patients who displayed a DAT positive test without hemolysis and who had not previously received a blood transfusion.

Selection for Evi1 activation in myelomonocytic leukemia induced by hyperactive signaling through wild-type NRas

Activation of NRas signaling is frequently found in human myeloid leukemia and can be induced by activating mutations as well as by mutations in receptors or signaling molecules upstream of NRas. To study NRas-induced leukemogenesis, we retrovirally overexpressed wild-type NRas in a murine bone marrow transplantation (BMT) model in C57BL/6J mice. Overexpression of wild-type NRas caused myelomonocytic leukemias ∼3 months after BMT in the majority of mice. A subset of mice (30%) developed malignant histiocytosis similar to mice that received mutationally activated NRas(G12D)-expressing bone marrow. Aberrant Ras signaling was demonstrated in cells expressing mutationally active or wild-type NRas, as increased activation of Erk and Akt was observed in both models. However, more NRas(G12D) were found to be in the activated, GTP-bound state in comparison with wild-type NRas. Consistent with observations reported for primary human myelomonocytic leukemia cells, Stat5 activation was also detected in murine leukemic cells. Furthermore, clonal evolution was detected in NRas wild-type-induced leukemias, including expansion of clones containing activating vector insertions in known oncogenes, such as Evi1 and Prdm16. In vitro cooperation of NRas and Evi1 improved long-term expansion of primary murine bone marrow cells. Evi1-positive cells upregulated Bcl-2 and may, therefore, provide anti-apoptotic signals that collaborate with the NRas-induced proliferative effects. As activation of Evi1 has been shown to coincide with NRAS mutations in human acute myeloid leukemia, our murine model recapitulates crucial events in human leukemogenesis.

Juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a rare childhood neoplasm with features characteristic of both myelodysplastic and myeloproliferative disorders. Children with JMML typically present with marked splenomegaly and hepatomegaly and varying degrees of lymphadenopathy, pallor, and skin rash. The peripheral blood usually show leukocytosis, absolute monocytosis, often with dysplastic features, anemia, and thrombocytopenia. While the bone marrow findings are less specific, hypercellularity due to myelomonocytic proliferation, mild dysplasia, and a reduced number of megakaryocytes are usually present. The hallmark of JMML is hypersensitivity of marrow progenitors to granulocyte-monocyte colony stimulating factor (GM-CSF) in vitro. Recent studies have shown that this abnormal proliferation is due to an aberrant signal transduction resulting from mutations in components of the RAS-signaling pathway. JMML is an aggressive neoplasm and, while hematopoietic stem cell transplantation is currently the only curative option, there is an unacceptably high relapse rate after transplant.

Molecular targets for the treatment of juvenile myelomonocytic leukemia

Significant advances in our understanding of the genetic defects and the pathogenesis of juvenile myelomonocytic leukemia (JMML) have been achieved in the last several years. The information gathered tremendously helps us in designing molecular targeted therapies for this otherwise fatal disease. Various approaches are being investigated to target defective pathways/molecules in this disease. However, effective therapy is still lacking. Development of specific target-based drugs for JMML remains a big challenge and represents a promising direction in this field.