Correlation of Clinical Features with the Mutational Status of GM-CSF Signaling Pathway-Related Genes in Children with Juvenile Myelomonocytic Leukemia

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1528-1528 ◽  
Author(s):  
Nao Yoshida ◽  
Hiroshi Yagasaki ◽  
Ayami Yoshimi ◽  
Yoshiyuki Takahashi ◽  
Yinyan Xu ◽  
...  
Keyword(s):  
Prognostic Factors ◽  
Clinical Outcome ◽  
Clinical Features ◽  
Juvenile Myelomonocytic Leukemia ◽  
Gm Csf ◽  
Ptpn11 Mutation ◽  
Mutational Status ◽  
Hbf Level ◽  
Mutation Age ◽  
Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder that affects young children. It is characterized by specific hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. Mutations in RAS, NF1, or PTPN11 positioned in the GM-CSF signal pathway, are thought to be involved in the pathogenesis of JMML. However, no information is available on the relationship between these mutations and clinical features of JMML. The impacts of these mutations on clinical outcome also remain unclear. We tested 49 Japanese children with JMML for N-RAS, K-RAS, and PTPN11 mutations and evaluated their clinical significance. We also assessed correlations between mutational status and clinical and laboratory findings, including age at diagnosis, fetal hemoglobin (HbF), platelet count, and cytogenetic abnormality, all which have been proposed as prognostic factors for JMML. Of the 49 JMML patients, cytogenetic abnormalities were detected in 13, including 8 with monosomy 7. For 2 patients, a clinical diagnosis of neurofibromatosis type 1 (NF1) was confirmed. PTPN11 and N-/K-RAS mutations were found in 22 (45%) and 8 (16%) patients, respectively. Neither PTPN11 nor RAS mutations nor NF1 were present in 17 (35%) patients, and no simultaneous aberrations in these genes were found. In patients with the PTPN11 mutation, age at diagnosis was older (35 vs 11 months; P=0.001, or 12 months; P<0.01) and HbF level was higher (31 vs 10%; P=0.03, or 16%; P<0.01) than for patients with the RAS mutation or without any aberration, suggesting that the clinical outcome for patients with the PTPN11 mutation might be poorer, because a higher HbF level and older age have been reported to be poor prognostic factors. In fact, overall survival (OS) at 5 years was lower for patients with the PTPN11 mutation than for those without (20±9% vs 58±9%; P=0.02). In addition to PTPN11 mutation, age older than 24 months (P<0.01) and abnormal karyotype (P=0.02) were also associated with poor prognosis for OS. Of the 49 patients, 33 received stem cell transplantation (SCT). OS probabilities for patients with and without a mutation in PTPN11 at 5 years after SCT were 25±10% and 64±12%, respectively (P=0.04). More importantly, mutation in PTPN11 was the only unfavorable factor for relapse after SCT (P<0.01). Seven patients died owing to relapse and 12 from complications. All patients who died after relapse had a PTPN11 mutation. In summary, our results suggest that PTPN11-mutated JMML might be a distinct subgroup with specific clinical characteristics and a poor outcome.

Correlation of Clinical Features with Mutational Status in Children with Juvenile Myelomonocytic Leukemia.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 2687-2687 ◽  
Author(s):  
Nao Yoshida ◽  
Hiroshi Yagasaki ◽  
Yinyan Xu ◽  
Makito Tanaka ◽  
Nobuhiro Nishio ◽  
...  
Keyword(s):  
Prognostic Factors ◽  
Cell Differentiation ◽  
Clinical Features ◽  
Novel Mutation ◽  
Juvenile Myelomonocytic Leukemia ◽  
Cytogenetic Abnormalities ◽  
Ras Mutations ◽  
Gm Csf ◽  
Mutational Status ◽  
Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder that affects young children. It is characterized by specific hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. Mutations in RAS, NF1, or PTPN11 positioned in the GM-CSF signal transduction pathway, which contribute to myeloid proliferation, have been recognized in the pathogenesis of JMML. Recently a multi-step model for leukemogenesis has been proposed. In this model, the pathogenesis of leukemia requires at least two classes of mutations:primary mutations of genes implicated in cell differentiation such as AML1 and PU.1 andadditional mutations of genes contributing to myeloid proliferation such as FLT3, RAS, and PTPN11. We hypothesized that in patients with JMML, in addition to known mutations of genes in the GM-CSF pathway involved in myeloid proliferation, potential causative mutations of other classes might be acquired. AML1 encodes a transcription factor that is essential for definitive hematopoiesis, and its mutations have recently been found in adults with acute myeloid leukemia and myelodysplastic syndrome. However, no information is available on the profiles of mutations in these genes and the relationship between these mutations and clinical features of JMML in children. We analyzed mutations of N-RAS, K-RAS, and PTPN11 in 50, and of AML1 in 30 Japanese children with JMML by direct sequencing. Correlation between the mutational status and clinical and laboratory findings, including age at diagnosis, sex, fetal hemoglobin (HbF), platelets count, cytogenetic abnormalities, and hepatomegaly, all which are suggested prognostic factors for JMML, were also assessed. Of the 50 patients with JMML, cytogenetic abnormalities were detected in 14, including 8 with monosomy 7. PTPN11 and N-/K-RAS mutations were found in 24 (48%) and 7 (14%) patients, respectively, and a novel mutation in AML1 was identified in one patient. No simultaneous mutations in these genes were found. Age at diagnosis was older (median 36 vs 11 months, p=0.0005) and HbF level was higher (31.0% vs 5.1%, p=0.033) in patients with the PTPN11 mutation than those with the RAS mutation. No difference was observed between patients with PTPN11 and RAS mutations in sex ratio, white blood cell count, platelets count, and the incidence of cytogenetic abnormalities and hepatomegaly. Our results suggest that the clinical outcome of patients with PTPN11 might differ from those with RAS mutations because a higher level of HbF and older age have been reported to be poor prognostic factors. In one patient with JMML, we identified a novel mutation in the AML1 gene that belongs to the class of genes contributing to cell differentiation instead of the class of genes in the GM-CSF pathway involved in myeloid proliferation.

scholarly journals Correlation of Clinical Features With the Mutational Status of GM-CSF Signaling Pathway-Related Genes in Juvenile Myelomonocytic Leukemia

2009 ◽  
Vol 65 (3) ◽  
pp. 334-340 ◽  
Author(s):  
Nao Yoshida ◽  
Hiroshi Yagasaki ◽  
Yinyan Xu ◽  
Kazuyuki Matsuda ◽  
Ayami Yoshimi ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Clinical Features ◽  
Juvenile Myelomonocytic Leukemia ◽  
Gm Csf ◽  
Mutational Status ◽  
Myelomonocytic Leukemia

A Favorable Outcome In Children with Juvenile Myelomonocytic Leukemia (JMML) with RAS Mutations

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 2909-2909 ◽  
Author(s):  
Sayoko Doisaki ◽  
Hideki Muramatsu ◽  
Asahito Hama ◽  
Akira Shimada ◽  
Yoshiyuki Takahashi ◽  
...  
Keyword(s):  
Platelet Count ◽  
Juvenile Myelomonocytic Leukemia ◽  
Term Survival ◽  
Hematopoietic Stem ◽  
Monosomy 7 ◽  
Ras Mutations ◽  
Gm Csf ◽  
Ras Genes ◽  
Hbf Level ◽  
Myelomonocytic Leukemia

Abstract Abstract 2909 Introduction: Juvenile myelomonocytic leukemia (JMML) is a rare clonal myeloproliferative disorder that affects young children. It is characterized by a specific hypersensitivity of JMML cells to granulocyte-macrophage colony-stimulating factor (GM-CSF) in vitro. The pathogenesis of JMML involves disruption of GM-CSF signal transduction resulting from mutations of the components of the RAS signaling pathway, including NF1, PTPN11, NRAS, and KRAS. Somatic point mutations of the RAS genes at codons 12, 13, and 61 are found in approximately 20% of patients. Although most patients with JMML die due to progressive disease within 12 months unless treated with hematopoietic stem cell transplantation (HSCT), Matsuda et al reported that JMML patients with NRAS or KRAS glycine to serine substitution improved spontaneously. Other groups in Europe did not confirm this observation, and treatment for patients with JMML and RAS mutations is controversial. Therefore, in the present study, we analyze the association between the mutational status of RAS and prognoses of patients with JMML. Patients and Methods: Eighty children diagnosed with JMML between 1988 and 2010 were studied retrospectively. We performed a mutational analysis of NRAS, KRAS, PTPN11, and C-CBL genes. Results: Seventeen patients (21%) had RAS mutations [NRAS (n = 13) and KRAS (n = 4)], while PTPN11 and C-CBL mutations were found in 28 patients (35%) and 5 patients (6.3%), respectively (Four patients were included in the previous report; Matsuda et al, Blood, 2007). Five children had clinical evidence of NF1 mutations. Among NRAS mutations, G12D and G13D were the most common (n = 6 and n = 5, respectively). Only one patient carried a G12S substitution, which was reported as a favorable mutation. Three patients with KRAS mutations had G13D substitutions. Compared to patients with other mutations or without any aberrations, patients with RAS mutations were significantly younger at diagnosis (median age: 12 months vs. 24 months, p = 0.011), while other known predictive factors such as HbF level and platelet count were not significantly different at diagnosis (median HbF level: 9.1 % vs. 22.2 %, p = 0.295; median platelet count: 27.5 × 109/L vs. 49.0 × 109/L, p = 0.390). Monosomy 7 was observed in seven patients without RAS mutations, and all patients with RAS mutations had normal karyotypes. Among untransplanted patients with RAS mutations, three achieved long-term survival (20, 84, and 209 months after diagnosis). The probability of 5-year overall survival estimated by the Kaplan-Meier method was significantly higher for patients with RAS mutations than for those without (85.7% vs. 30.4%, p = 0.033). Conclusion: These results suggest that JMML patients with RAS mutations may be a distinct subgroup with favorable outcomes in spite of other than G12S. Disclosures: No relevant conflicts of interest to declare.

Myelodysplastic and Myeloproliferative Disorders of Childhood: A Study of 167 Patients

Blood ◽  
1999 ◽  
Vol 93 (2) ◽  
pp. 459-466 ◽  
Author(s):  
Sandra Luna-Fineman ◽  
Kevin M. Shannon ◽  
Susan K. Atwater ◽  
Jeffrey Davis ◽  
Margaret Masterson ◽  
...  
Keyword(s):  
Clinical Features ◽  
Age At Onset ◽  
Myeloproliferative Disorders ◽  
Juvenile Myelomonocytic Leukemia ◽  
Genetic Associations ◽  
Adult Type ◽  
Hemoglobin F ◽  
Monosomy 7 ◽  
Prognostic Features ◽  
Myelomonocytic Leukemia

Abstract Myelodysplastic syndromes (MDS) and myeloproliferative syndromes (MPS) of childhood are a heterogeneous group of clonal disorders of hematopoiesis with overlapping clinical features and inconsistent nomenclature. Although a number of genetic conditions have been associated with MDS and MPS, the overall contribution of inherited predispositions is uncertain. We report a retrospective study examining clinical features, genetic associations, and outcomes in 167 children with MDS and MPS. Of these patients, 48 had an associated constitutional disorder. One hundred one patients had adult-type myelodysplastic syndrome (A-MDS), 60 had juvenile myelomonocytic leukemia (JMML), and 6 infants with Down syndrome had a transient myeloproliferative syndrome (TMS). JMML was characterized by young age at onset and prominent hepatosplenomegaly, whereas patients with A-MDS were older and had little or no organomegaly. The most common cytogenetic abnormalities were monosomy 7 or del(7q) (53 cases); this was common both in patients with JMML and those with A-MDS. Leukemic transformation was observed in 32% of patients, usually within 2 years of diagnosis. Survival was 25% at 16 years. Favorable prognostic features at diagnosis included age less than 2 years and a hemoglobin F level of less than 10%. Older patients tended to present with an adult-type MDS that is accommodated within the French-American-British system. In contrast, infants and young children typically developed unique disorders with overlapping features of MDS and MPS. Although the type and intensity of therapy varied markedly in this study, the overall outcome was poor except in patients with TMS.

scholarly journals Somatic PTPN11 mutation with a heterogeneous clonal origin in children with juvenile myelomonocytic leukemia

Leukemia ◽  
2004 ◽  
Vol 18 (6) ◽  
pp. 1142-1144 ◽  
Author(s):  
H Shimada ◽  
T Mori ◽  
N Shimasaki ◽  
K Shimizu ◽  
T Takahashi ◽  
...  
Keyword(s):  
Juvenile Myelomonocytic Leukemia ◽  
Ptpn11 Mutation ◽  
Clonal Origin ◽  
Myelomonocytic Leukemia

Rapamycin -- a Potential Mechanistically Targeted Therapeutic for Juvenile Myelomonocytic Leukemia.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 2378-2378
Author(s):  
Y. Lucy Liu ◽  
Robert P. Castleberry ◽  
Peter Dean Emanuel
Keyword(s):  
Philadelphia Chromosome ◽  
Disease Free Survival ◽  
Juvenile Myelomonocytic Leukemia ◽  
Ras Signaling ◽  
Sensitivity Testing ◽  
Blood Concentrations ◽  
Patient Sample ◽  
Gm Csf ◽  
Myelomonocytic Leukemia

Abstract Juvenile myelomonocytic leukemia (JMML) is a mixed myelodysplastic /myeloproliferative disorder (MDS/MPD) of infancy and early childhood. It is characterized by monocytosis, leukocytosis, elevated fetal hemoglobin, hypersensitivity to granulocyte-macrophage colony-stimulating factor (GM-CSF), a low percentage of myeloblasts in the bone marrow, and absence of the Philadelphia chromosome or the BCR/ABL fusion gene. The pathogenesis of JMML has been clearly and definitively linked to dysregulated signal transduction through the RAS signaling pathway. A series of studies conducted over the last decade have shown that mutations or other abnormalities in RAS, NF1, and PTPN11, are potentially responsible for the pathogenesis of JMML in up to 75% of cases. Treatment has been very difficult. There is no effective therapy for JMML. Only allogeneic stem cell transplantation (SCT) can extend survival. However, the relapse rate from allogeneic SCT is inordinately high in JMML (28–55%), with 5-year disease-free survival rates of 25-40%. Rapamycin is a macrolide antibiotic with established clinical applications in organ transplantation. Recent studies have proved that the Mammalian Target of Rapamycin (mTOR) plays an important role in cytokine receptor signaling and induction of apoptosis. Numerous studies have suggested that mTOR functions as a nutritional checkpoint and is connected to energy sensing through AMP-dependent kinase (AMPK) which senses the AMP: ATP ratio in cells. Its function is regulated by the RAS/PI3-kinase pathway. In searching for novel mechanistically-targeted reagents to treat JMML, we conducted an in vitro pilot study with JMML cells. The CFU-GM formation assay was used to test the therapeutic sensitivity of rapamycin to JMML cells. Mononuclear cells (MNCs) from peripheral blood of 9 JMML patients were collected and plated on 0.3% agar medium with rapamycin at a concentration of 1-8nM(0.91-7.28μg/L) and carrier (DMSO). Greater than 50% inhibition of spontaneous CFU-GM growth was observed in all cultures in a dose-dependent fashion, with the exception of one patient sample which had colonies resistant to rapamycin. The effective concentrations in our cultures are equivalent to the safe and tolerable whole blood concentrations achieved in organ transplant patients in clinical settings (5-30μg/L). Our data suggests that rapamycin may be considered as a potentially safe and effective reagent to treat JMML, but that in vitro sensitivity testing might be recommended since one patient sample demonstrated complete resistance to rapamycin in vitro. Further studies are ongoing to explore the mechanism of rapamycin in inhibiting hypersensitivity of JMML cells to GM-CSF.

PTPN11 Mutational Spectrum in Juvenile Myelomonocytic Leukemia and Noonan Syndrome.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 3417-3417 ◽  
Author(s):  
Christian P. Kratz ◽  
Charlotte M. Niemeyer ◽  
Bruce D. Gelb ◽  
Marco Tartaglia ◽  
Mignon L. Loh
Keyword(s):  
Cell Fate ◽  
Noonan Syndrome ◽  
Somatic Mutations ◽  
Heart Defects ◽  
Lymphoblastic Leukemia ◽  
Juvenile Myelomonocytic Leukemia ◽  
Acute Monocytic Leukemia ◽  
Missense Mutations ◽  
Ptpn11 Mutation ◽  
Myelomonocytic Leukemia

Abstract Somatic, heterozygous missense mutations in the PTPN11 proto-oncogene encoding SHP-2 are identified in 35% of patients with juvenile myelomonocytic leukemia (JMML). Other non-syndromic hematologic malignancies in which somatic PTPN11 mutations have been detected are pediatric myelodysplastic syndrome, acute monocytic leukemia (FAB-M5 AML) and common or B-cell precursor acute lymphoblastic leukemia. Germline PTPN11 mutations are found in 50% of patients with Noonan syndrome (NS), an autosomal dominant disorder characterized by facial anomalies, short stature and congenital heart defects. Infants with NS are predisposed to developing JMML (NS/JMML); however, the course of NS/JMML tends to be milder and self-resolving. JMML that is not associated with NS have a poor prognosis and are currently being treated with intensive regimens such stem cell transplantation. Differentiating JMML from NS/JMML is of critical clinical relevance and also provides interesting questions about the pathogenesis of these diseases. To that end, we have compared the spectrum of mutations in patients with isolated JMML, NS/JMML and NS alone. The assembly of all known published and unpublished germline and somatic exon 3 and 13 PTPN11 mutations detected in ours and other laboratories (78 pts with PTPN11 mutation positive isolated JMML; 18 pts with PTPN11 mutation positive NS/JMML) reveal that the identity of the affected residues or the type of substitution differ between NS and JMML, even though the resulting molecular defects appear to be functionally similar. In NS defects in exons 4, 7 and 8 account for approximately one-half of cases. On the contrary, mutations affecting these exons are rarely identified in JMML. A few germline NS-causative mutations affect the same residues of SHP-2 that are also altered by somatic mutations in non-syndromic JMML. In almost all of the cases, the germline and somatic mutations affecting identical residues differ with respect to the amino acid substitution. There are 2 major hot spots: 7 out of 18 patients (39%) with NS/JMML carry the T73I substitution. In isolated JMML the E76K mutation is detected most often (18 out of 78 patients (23%)). We describe 2 novel JMML mutations (E76M, G503V) and 2 novel NS/JMML mutations (R598W, S502A). Six mutations associated with isolated NS are also observed in NS/JMML. These findings imply the presence of a germline mutation needs to be excluded in all mutation positive neonates with presumed isolated JMML. In addition, our findings raise a number of research questions: First, are somatic PTPN11 mutations alone sufficient to initate leukemia and what are the molecular factors influencing the consequences of a PTPN11 mutation in hematopoietic cells? Second, do identical mutations have different consequences on cell fate of hematopoetic cells depending on whether they occur as germline or somatic events? Do some patients with isolated NS and PTPN11 mutation develop transient myeloproliferation of hematopoetic cells which may be subtle and unrecognised?

CREB Deficiency: A Potential Critical Factor for Selective GM-CSF Hypersensitivity in Juvenile Myelomonocytic Leukemia.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2604-2604
Author(s):  
Y. Lucy Liu ◽  
Priyangi A Malaviarachchi ◽  
Shelly Y. Lensing ◽  
Robert P. Castleberry ◽  
Peter Dean Emanuel
Keyword(s):  
Conflicts Of Interest ◽  
Myeloproliferative Neoplasm ◽  
Juvenile Myelomonocytic Leukemia ◽  
Ras Signaling ◽  
Camp Response Element ◽  
Response Element ◽  
Creb Protein ◽  
Gm Csf ◽  
Myelomonocytic Leukemia ◽  
Normal Controls

Abstract Abstract 2604 Poster Board II-580 Juvenile myelomonocytic leukemia (JMML) is a mixed myelodysplastic /myeloproliferative neoplasm (MDS/MPN) of infancy and early childhood. The pathogenesis of JMML has been linked to dysregulated signal transduction through the NF1/RAS signaling pathway and PTPN11. This dysregulation results in JMML cells demonstrating selective hypersensitivity to GM-CSF in in vitro dose-response assays. Since JMML hematopoietic progenitor cells are selectively hypersensitive to (rather than independent of) GM-CSF, it is rational to hypothesize that the function of the GM-CSF receptor in JMML patients is not constitutively over-active unless stimulated by the cytokine. We previously reported that PTEN is deficient in JMML patients. PTEN expression is up-regulated by Egr-1, which is one of the targets of the cAMP-response-element-binding protein (CREB). CREB, as a transcriptional factor, is expressed ubiquitously and bound to the cAMP-response-element (CRE) of the Egr-1 promoter. After phosphorylation at serine 133, CREB selectively activates the transcription of Egr-1 in response to GM-CSF stimulation in hematopoietic cells. We evaluated the CREB protein level in peripheral blood or bone marrow samples collected from 26 JMML patients. Mononuclear cells (MNCs) were isolated and lysed in lysis buffer at a density of 107/100μl. Protein levels of CREB were evaluated by ELISA and Western-blot. We found that 22/26 (85%) of subjects were substantially CREB deficient while they had constitutively high activity of MAP kinase (Erk-1/2). In comparison to normal controls (n=7), the median level of total CREB protein by ELISA was significantly lower in JMML subjects (0.62 vs 8.85 ng/mg BSA in normal controls; p=0.006). The mechanism that causes CREB deficiency in JMML is under further investigation and further results may be available to present at the meeting. This is the first evidence that CREB, a critical component downstream of the GM-CSF receptor, is highly deficient in the majority of JMML cases. Disclosures: No relevant conflicts of interest to declare.

Patient-Derived Induced Pluripotent Stem Cells Recapitulate Hematopoietic Abnormalities of Juvenile Myelomonocytic Leukemia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 637-637
Author(s):  
Gandre-Babbe Shilpa ◽  
Stella T Chou ◽  
Deborah L. French ◽  
Michelle Kang ◽  
Julie Weng ◽  
...  
Keyword(s):  
Stem Cells ◽  
Cord Blood ◽  
Induced Pluripotent Stem Cells ◽  
Pluripotent Stem Cells ◽  
Vector System ◽  
Juvenile Myelomonocytic Leukemia ◽  
Malignant Cells ◽  
Gm Csf ◽  
Induced Pluripotent ◽  
Myelomonocytic Leukemia

Abstract Abstract 637 Juvenile Myelomonocytic Leukemia (JMML) is an aggressive childhood myeloproliferative disorder caused by NF1, NRAS, KRAS, PTPN11 or CBL gene mutations that induce Ras pathway activation with associated hypersensitivity to cytokine stimulation in myeloid progenitor cells. Understanding the pathophysiology of JMML and developing new treatments is constrained by limited access to relevant patient material. To address this problem, we generated induced pluripotent stem cells (iPSCs) from normal neonatal umbilical cord blood and two JMML patients with different mutations: 1) a somatic heterozygous E76K substitution in PTPN11 and 2) a CBL Y371H substitution arising from a germline mutation. We created iPSCs from the patient's heterozygous CBL Y371H newborn cord blood cells prior to the diagnosis of JMML and then from peripheral blood at age 7 months, when JMML ensued with outgrowth of CBL Y371H homozygous malignant cells. We reprogrammed control and malignant cells using the STEMCCA lentiviral vector system that expresses OCT4, KLF4, MYC and SOX2 in a doxycyline-inducible fashion. Resultant iPSCs exhibited hallmark features after more than twenty passages, including characteristic morphology, expression of endogenous pluripotency markers, silencing of viral reprogramming genes in the absence of doxycycline, normal karyotype and formation of endoderm-, ectoderm- and mesoderm-derived tissues in teratoma assays. Relevant PTPN11 and CBL genotypes of these clones were confirmed by DNA sequencing. Selected iPSC clones were differentiated into blood by inducing the formation of embryoid bodies in serum free medium with defined cytokines. By day 8–9, hematopoietic progenitors (CD43+, CD235+, CD41+) with erythroid, megakaryocytic and myeloid potential developed from both control (n = 2 lines) and JMML iPSCs (n= 2 lines from each patient). In methylcellulose colony assays, JMML progenitors exhibited relative hypersensitivity to GM-CSF, as reflected by increased numbers and larger size of myeloid colonies at limiting GM-CSF concentrations. In liquid cultures containing SCF, TPO, EPO, IL-3, IL-11 and IGF-1, with or without GM-CSF, the JMML progenitors produced increased proportions of CD33+CD14+ myelomonocytic cells compared to controls. Moreover, in GM-CSF dose-response assays, single cell phospho-flow cytometry analysis showed sustained STAT5 activation in JMML myeloid cells vs. controls. Thus, key pathological features of JMML, including propensity to myelomonocytic cell expansion and GM-CSF hypersensitivity, are recapitulated by in vitro differentiation of JMML iPSCs. Our findings illustrate the utility of iPSCs for modeling human blood disorders and more specifically, provide renewable sources of biologically relevant, patient-derived cells in which to explore the pathophysiology and therapy of JMML. Disclosures: No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document