Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic/myeloproliferative disorder of early childhood characterized by mutations of the RAS-RAF-MAP kinase signaling pathway.
This is the first study to associate somatically acquired WASP mutations with a hematopoietic malignancy and increases insight in the complexity of the genomic landscape of JMML that shows low recurrent mutations concomitant with general hyperactivation of RAS pathway signaling.
We genotyped a cohort of patients with chronic myelomonocytic leukemia, secondary acute myeloid leukemia derived from chronic myelomonocytic leukemia and juvenile myelomonocytic leukemia for somatic mutations in U2AF1, SRSF2, SF3B1 and in the other 12 most frequently affected genes in these conditions.
The same rearrangement of gene T-cell receptor gamma (TCR gamma) was detected upon diagnosis of JMML and ALL, suggesting that both neoplasias may have evolved from the same clone.
These data indicate that abnormalities of the p53 gene are rare in JMML and not responsible for acute transformation, but could be involved in the pathogenesis of some cases of JMML.
A germline mutation in the NF1 gene and sequential inactivation of p53 alleles in the malignant clone of JCML raise the possibility of a correlation between NF1 and p53 genes in the tumorigenesis of JCML.
Chemical inhibition of TNK2 blocked MAPK signaling and colony formation in vitro and decreased disease burden in a patient with PTPN11-mutant JMML who was treated with the multikinase (including TNK2) inhibitor dasatinib.
We therefore analyzed samples obtained from 57 patients with a variety of hematologic malignancies (21, acute myelogenous leukemia; 14, acute lymphoblastic leukemia; 12, Philadelphia chromosome-positive chronic myelogenous leukemia [blast phase] or acute leukemia; 5, chronic lymphocytic leukemia; and 5, chronic myelomonocytic leukemia) for expression of interleukin-1 beta (IL-1 beta) and tumor necrosis factor-alpha (TNF-alpha) transcripts on Northern blots.
Sixteen patients with CML, six patients with AML, two patients with acute lymphatic leukemia (ALL) and one with chronic myelomonocytic leukemia (CMMOL), all with known cytogenetic abnormalities, were evaluated according to their CD90 (Thy-1)-positive or -negative phenotype.
Seven-day co-culture of GMR CAR T cells resulted in a marked suppression of JMML CD34(+) cell proliferation, particularly CD34(+)CD38(-) cell proliferation stimulated with stem cell factor and thrombopoietin on AGM-S3 cells.
We previously reported that stimulation of JMML CD34<sup>+</sup> cells with stem cell factor and thrombopoietin on irradiated murine AGM-S3 cells led to substantial expansion of JMML CD34<sup>+</sup> cells that contained leukemic stem cells capable of transplantation into immunodeficient mice.
AGM-S3 cells in concert with stem cell factor plus thrombopoietin increased the numbers of peripheral blood CD34(+) cells to approximately 20-fold of the input value after 2 weeks in nine JMML patients with either PTPN11 mutations or RAS mutations, who received allogeneic hematopoietic transplantation.
Here, we describe a patient with juvenile myelomonocytic leukemia in which a prominent CD141+ cell population was identified most consistent with CD141+ MDCs based on phenotypic similarity with normal CD141+ MDCs.
We identified cases which either: (1) fulfilled the 2008 World Health Organization criteria for primary myelofibrosis but had absolute monocytosis and, when available, chronic myelomonocytic leukemia-related mutations (ASXL1, SRSF2, TET2) or (2) fulfilled criteria of chronic myelomonocytic leukemia but had megakaryocytic proliferation and atypia, marrow fibrosis, and myeloproliferative-type driver mutations (JAK2, MPL, CALR).