Droplet digital PCR: An effective method for monitoring and prognostic evaluation of minimal residual disease in JMML.

Juvenile myelomonocytic leukaemia (JMML) is a rare myeloproliferative neoplasm requiring haematopoietic stem cell transplantation (HSCT) for potential cure. Relapse poses a significant obstacle to JMML HSCT treatment, as the lack of effective minimal residual disease (MRD)-monitoring methods leads to delayed interventions. This retrospective study utilized the droplet digital PCR (ddPCR) technique, a highly sensitive nucleic acid detection and quantification technique, to monitor MRD in 32 JMML patients. The results demonstrated that ddPCR detected relapse manifestations earlier than traditional methods and uncovered molecular insights into JMML MRD dynamics. The findings emphasized a critical 1- to 3-month window post-HSCT for detecting molecular relapse, with 66.7% (8/12) of relapses occurring within this period. Slow MRD clearance post-HSCT was observed, as 65% (13/20) of non-relapse patients took over 6 months to achieve ddPCR-MRD negativity. Furthermore, bone marrow ddPCR-MRD levels at 1-month post-HSCT proved to be prognostically significant. Relapsed patients exhibited significantly elevated ddPCR-MRD levels at this time point (p = 0.026), with a cut-off of 0.465% effectively stratifying overall survival (p = 0.007), event-free survival (p = 0.035) and cumulative incidence of relapse (p = 0.035). In conclusion, this study underscored ddPCR's superiority in JMML MRD monitoring post-HSCT. It provided valuable insights into JMML MRD dynamics, offering guidance for the effective management of JMML.

Phenotypic profiling of CD34+ cells by advanced flow cytometry improves diagnosis of juvenile myelomonocytic leukemia.

Diagnostic criteria for juvenile myelomonocytic leukemia (JMML) are currently well defined, however in some patients diagnosis still remains a challenge. Flow cytometry is a well established tool for diagnosis and follow-up of hematological malignancies, nevertheless it is not routinely used for JMML diagnosis. Herewith, we characterized the CD34+ hematopoietic precursor cells collected from 31 children with JMML using a combination of standardized EuroFlow antibody panels to assess the ability to discriminate JMML cells from normal/reactive bone marrow cell as controls (n=29) or from cells of children with other hematological diseases mimicking JMML (n=9). CD34+ precursors in JMML showed markedly reduced B-cell and erythroid-committed precursors compared to controls, whereas monocytic and CD7+ lymphoid precursors were significantly expanded. Moreover, aberrant immunophenotypes were consistently present in CD34+ precursors in JMML, while they were virtually absent in controls. Multivariate logistic regression analysis showed that combined assessment of the number of CD34+CD7+ lymphoid precursors and CD34+ aberrant precursors or erythroid precursors had a great potential in discriminating JMMLs versus controls. Importantly our scoring model allowed highly efficient discrimination of truly JMML versus patients with JMML-like diseases. In conclusion, we show for the first time that CD34+ precursors from JMML patients display a unique immunophenotypic profile which might contribute to a fast and accurate diagnosis of JMML worldwide by applying an easy to standardize single eight-color antibody combination.

A predictive classifier of poor prognosis in transplanted patients with juvenile myelomonocytic leukemia: a study on behalf of the Société Francophone de Greffe de Moelle et de Thérapie Cellulaire.

Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric myeloproliferative neoplasm requiring hematopoietic stem cell transplantation (HSCT) in most cases. We retrospectively analyzed 119 JMML patients who underwent first allogeneic HSCT between 2002 and 2021. The majority (97%) carried a RAS-pathway mutation, and 62% exhibited karyotypic alterations or additional mutations in SETBP1, ASXL1, JAK3 and/or the RAS pathway. Relapse was the primary cause of death, with a 5-year cumulative incidence of 24.6% (95% CI: 17.1-32.9). Toxic deaths occurred in 12 patients, resulting in treatment-related mortality (TRM) of 9.0% (95% CI: 4.6-15.3). The 5-year overall (OS) and event-free survival were 73.6% (95% CI: 65.7-82.4) and 66.4% (95% CI: 58.2-75.8), respectively. Four independent adverse prognostic factors for OS were identified: age at diagnosis >2 years, time from diagnosis to HSCT ≥6 months, monocyte count at diagnosis >7.2x109/L, and the presence of additional genetic alterations. Based on these factors, we proposed a predictive classifier. Patients with 3 or more predictors (21% of the cohort) had a 5-year OS of 34.2%, whereas those with none (7%) had a 5-year OS of 100%. Our study demonstrates improved transplant outcomes compared to prior published data, which can be attributed to the synergistic impacts of a low TRM and a reduced, yet still substantial, relapse incidence. By integrating genetic information with clinical and hematologic features, we have devised a predictive classifier. This classifier effectively identifies a subgroup of patients who are at a heightened risk of unfavorable post-transplant outcomes who would benefit from novel therapeutic agents and post-transplant strategies.

Noonan Syndrome-related Myeloproliferative Disorder Occurring in the Neonatal Period: Case Report and Literature Review.

Noonan syndrome-related myeloproliferative disorder (NS/MPD) and juvenile myelomonocytic leukemia (JMML) are rare MPDs that occur in young children. We herein report a case of NS/MPD with neonatal onset. The patient had a characteristic appearance and high monocyte count in the peripheral blood and bone marrow. Genetic testing showed the E139D mutation in PTPN11 ; however, the patient did not meet all the diagnostic criteria for JMML, and we thus diagnosed him with NS/MPD. Eight other cases of NS/MPD with neonatal onset are also summarized. The initial presentation varied, and the prognosis was considered poor compared with previous reports of NS/MPD.

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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.

Therapy-related myeloid neoplasms resembling juvenile myelomonocytic leukemia: a case series and review of the literature.

Therapy-related myeloid neoplasms (t-MN) are a distinct subgroup of myeloid malignancies with a poor prognosis that include cases of therapy-related myelodysplastic syndrome (t-MDS), therapy-related myeloproliferative neoplasms (t-MPN) and therapy-related acute myeloid leukemia (t-AML). Here, we report a series of patients with clinical features consistent with juvenile myelomonocytic leukemia (JMML), an overlap syndrome of MDS and myeloproliferative neoplasms that developed after treatment for another malignancy.

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 ß2-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.

Immunophenotypic characteristics of juvenile myelomonocytic leukaemia and their relation with the molecular subgroups of the disease.

The diagnosis of juvenile myelomonocytic leukaemia (JMML) is based on clinical, laboratory and molecular features but immunophenotyping [multiparametric flow cytometry (MFC)] has not been used routinely. In the present study, we describe the flow cytometric features at diagnosis with special attention to the distribution of monocytic subsets and the relation between MFC and molecular subgroups. MFC was performed with an eight-colour platform based on Euroflow. We studied 33 JMML cases. CD34+ /CD117+ /CD13+ cells >2% was found in 25 cases, and 51·5% presented an aberrant expression of CD7. A decrease of CD34+ /CD19+ /CD10+ cells was seen in eight cases and in four they were absent. The granulocytic population had a decreased side scatter in 29 cases. Bone marrow monocytic precursors were increased in 28 patients, with a decrease in classical monocytes (median 80·7%) and increase in CD16+ (intermediate and non-classical). A more pronounced increase in myeloid CD34+ cells was seen in patients with Neurofibromatosis type 1 (NF1) and tyrosine-protein phosphatase non-receptor type 11 (PTPN11), with aberrant CD7 expression in four of six and 10/12 patients respectively. Thus, JMML shows an immunophenotypic profile similar to myelodysplastic syndromes, and a different monocyte subset distribution when compared with chronic MML. MFC proved to be an important diagnostic tool that can help in differential diagnosis with other clonal diseases with monocytosis.

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.

NUP98-NSD1 Driven MDS/MPN in Childhood Masquerading as JMML.

Overlapping myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are clonal hematopoietic disorders with features of myelodysplasia and myeloproliferation. The only well-characterized MDS/MPN in children is juvenile myelomonocytic leukemia, an aggressive disorder of infants and toddlers. The biochemical hallmark of this disease is hyperactivation of the Ras/MAPK signaling pathway caused by mutations in Ras pathway genes in more than 90% of patients. Translocations involving receptor tyrosine kinases have been identified in rare cases. Here, we report a 2-year-old patient who presented with MDS/MPN driven by a cytogenetically cryptic NUP98-NSD1 fusion, a translocation thought to exclusively occur in patients with acute myeloid leukemia.

Morphologic and Immunophenotypic Differences in Juvenile Myelomonocytic Leukemias With CBL and Other Canonical RAS-pathway Gene Mutations: A Single Institutional Experience.

The diagnostic criteria for juvenile myelomonocytic leukemia have recently been revised to include clinical findings and RAS-pathway gene mutations per the 2016 World Health Organization Classification of Tumors of Hematopoietic and Lymphoid Tissues. Differing clinical behaviors have been observed in cases with CBL versus other RAS-pathway gene (RAS-p) mutations, notably the patients with CBL mutations can be self-limiting with spontaneous resolution. Additional clinical characteristics and histopathologic findings between these subsets are less well-described. We performed a retrospective search and identified cases with either CBL or RAS-p mutations, as per targeted and/or massively parallel sequencing. Eight patients had sufficient material for review, including cytogenetic studies and peripheral blood, bone marrow aspirate, and/or biopsy with flow cytometry analyses. Three patients showed CBL mutations and lower percentages of hemoglobin F and peripheral blood absolute monocyte counts, lesser degrees of leukocytosis compared with the RAS-p cohort, and normal megakaryocyte morphology and myeloblast immunophenotypes. Two of these patients were managed with observation only and experienced resolution of their disease. The patients with RAS-p mutations had severe thrombocytopenia, moderate to severe anemia, and experienced variable clinical outcomes. Abnormal megakaryocyte morphology and decreased numbers of megakaryocytes were seen in cases with RAS-p mutations. In addition, 3 of 4 cases with flow cytometry data demonstrated aberrant CD7 expression in myeloblasts. Our study is the first to identify morphologic and immunophenotypic differences between juvenile myelomonocytic leukemia cases with CBL or RAS-p mutations, and further supports previous reports of significantly different clinical behaviors between these subsets of patients.

Diagnosis and treatment of juvenile myelomonocytic leukemia in Slovak Republic: novel approaches.

Juvenile myelomonocytic leukemia (JMML) is a rare, aggressive clonal myeloproliferative disorder of infancy and early childhood caused by oncogenic mutations in genes involved in the Ras pathway. Long-term survival has only been achieved with hematopoietic stem cell transplantation (HSCT), being able to cure more than 50% patients. To manage the disease before HSCT remains an important issue with constant searching for optimal treatment modalities. According to several retrospective analyses, azacitidine (AZA) induced clinical and molecular responses in patients with relapsed JMML pre-transplant and post-transplant, suggesting its use as a promising "bridging" therapy before HSCT. In this paper we report our first consecutive cohort of patients with JMML treated at our institution as well as our experience with the diagnosis, novel treatment and management of these patients before the HSCT. We present 6 patients with JMML, harboring different somatic mutations (PTPN11 and NRAS), with distinct clinical features; 3 of them had been treated with AZA 75 mg/m2 i.v. on days 1 to 7 of a 28-day cycle before the HSCT. Response to therapy was evaluated after each cycle in accordance with the International response criteria. One patient had a progression of splenomegaly during the treatment and after three cycles he was urgently transplanted. At the present, he is remaining in complete remission 3 years after HSCT. Two patients showed impressive response following the first cycle of the therapy with a regression of splenomegaly and monocyte count, normalized leukocytes, platelets and absent blasts in peripheral blood. The treatment was well tolerated with no adverse effect recorded. The clinical activity and favorable toxicity of AZA in JMML provide a rationale for its use as a "bridging" therapy before HSCT. Prospective trials with accompanying translational studies are required to provide further information regarding individual factors that may direct the most appropriate choice of pretransplantation therapy.

Complete Resolution of Lymphoid Interstitial Pneumonia in a Patient With Juvenile Myelomonocytic Leukemia Treated With Allogeneic Bone Marrow Transplant: Killing 2 Birds With 1 Stone.

Lymphoid interstitial pneumonia (LIP) is a rare disease characterized by benign reactive polyclonal proliferation of bronchus-associated lymphoid tissue after exposure to inhaled or circulating antigen(s), leading to a disease symptomatology similar to idiopathic interstitial pneumonia. Its association with diseases that are caused due to immune dysregulation (autoimmune diseases, congenital/acquired immunodeficiency, and allogeneic bone marrow transplant) and response to immunomodulatory/suppressive medications suggests an immunologic pathophysiology. Although LIP has been reported in association with lymphoproliferative diseases like Castleman disease, it has never been described in patients with leukemia. We report the first case of LIP in a patient with juvenile myelomonocytic leukemia (JMML) who was found to have a novel germline mutation of unknown significance in additional sex combs-like-1 (ASXL1) gene and a pathogenic somatic mutation of protein tyrosine phosphatase, nonreceptor type 11 (PTPN11) gene at diagnosis. The patient underwent a matched unrelated bone marrow transplant for JMML with complete resolution of JMML and LIP with no recurrence to date. We also emphasize the importance of considering LIP in differential diagnosis of pulmonary lesions seen in conjunction with hematologic malignancies and distinguishing it from malignant infiltration of the lung.

Cutaneous involvement in an 8-year-old boy with Ras-associated autoimmune leucoproliferative disorder (RALD).

Ras-associated autoimmune leucoproliferative disorder (RALD) is a nonmalignant syndrome associated with somatic KRAS mutations. We report a patient with RALD and cutaneous lesions, the first such case reported, to our knowledge. An 8-year-old boy presented with erythematous plaques on his face and body, along with lymphadenopathies and spleen enlargement without systemic symptoms. An increased number of monocytes were found in skin biopsy, peripheral blood and bone marrow (BM). Juvenile myelomonocytic leukaemia (JMML) was suspected. Genetic study using peripheral blood showed no mutations in the KRAS, PTPN11, NRAS, CBL or BCR-ABL genes, but bone marrow analysis revealed a mutation (p-G12S/c.34 G>A) in the KRAS gene. The karyotype was normal. No KRAS mutations were found using molecular analysis of saliva. The diagnosis of RALD was proposed. The differential diagnosis between RALD and JMML is challenging because there are no established criteria to differentiate between them. The clinical course of RALD is uncertain, so long-term follow-up is recommended.

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.