Juvenile myelomonocytic leukemia

The elevation of red blood cell distribution width is an independent prognostic factor for juvenile myelomonocytic leukemia

Juvenile myelomonocytic leukemia (JMML) is a disorder characterized by the simultaneous presence of myeloproliferative and myelodysplastic features, primarily affecting infants and young children. Due to the heterogeneous genetic background among patients, the current clinical and laboratory prognostic features are insufficient for accurately predicting outcomes. Thus, there is a pressing need to identify novel prognostic indicators. Red cell distribution width (RDW) is a critical parameter reflecting the variability in erythrocyte size. Recent studies have emphasized that elevated RDW serves as a valuable predictive marker for unfavorable outcomes across various diseases. However, the prognostic role of RDW in JMML remains unclear. Patients with JMML from our single-center cohort between January 2008 and December 2019 were included. Overall, 77 patients were eligible. Multivariate Cox proportional hazard models showed that patients with red cell distribution width coefficient of variation (RDW-CV) >17.35% at diagnosis were susceptible to much worse overall survival rate (hazard ratio [HR] = 5.22, confidence interval [CI] = 1.50-18.21, P = .010). Besides, the combination of RDW elevation and protein phosphatase non-receptor type 11 (PTPN11) mutation was likely to predict a subgroup with the worst outcomes in our cohort. RDW is an independent prognostic variable in JMML subjects. RDW may be regarded as an inexpensive biomarker to predict the clinical outcome in patients with JMML.

Donor Killer Immunoglobulin Receptor Gene Content and Ligand Matching and Outcomes of Pediatric Patients with Juvenile Myelomonocytic Leukemia Following Unrelated Donor Transplantation

Natural killer (NK) cell determinants predict relapse-free survival after allogeneic hematopoietic cell transplantation (HCT) for acute myelogenous leukemia, and previous studies have shown a beneficial graft-versus-leukemia effect in patients with juvenile myelomonocytic leukemia (JMML). However, whether NK cell determinants predict protection against relapse for JMML patients undergoing HCT is unknown. Therefore, we investigated NK cell-related donor and recipient immunogenetics as determinants of HCT outcomes in patients with JMML. Patients with JMML (age 0 to <19 years) who underwent a first allogeneic HCT from an unrelated donor between 2000 and 2017 and had available donor samples from the Center for International Blood and Marrow Transplant Research Repository were included. Donor killer immunoglobulin receptor (KIR) typing was performed on pre-HCT samples. The primary endpoint was disease-free survival (DFS); secondary endpoints included relapse, grade II-IV acute graft versus-host-disease (aGVHD), chronic GVHD (cGVHD), GVHD-free relapse-free survival, transplantation-related mortality, and overall survival (OS). Donor KIR models tested included KIR genotype (AA versus Bx), B content (0-1 versus ≥2), centromeric and telomeric region score (AA versus AB versus BB), B content score (best, better, or neutral), composite score (2 versus 3 versus 4), activating KIR content, and the presence of KIR2DS4. Ligand-ligand and KIR-ligand mismatch effects on outcomes were analyzed in HLA-mismatched donors (≤7/8; n = 74) only. Univariate analyses were performed for primary and secondary outcomes of interest, with a P value <.05 considered significant. One hundred sixty-five patients (113 males), with a median follow-up of 85 months (range, 6 to 216 months) met the study criteria. Of these, 111 underwent an unrelated donor HCT and 54 underwent a UCB HCT. Almost all (n = 161; 98%) received a myeloablative conditioning regimen. After exclusion of recipients of reduced-intensity/nonmyeloablative conditioning regimens and ex vivo T cell-depleted grafts (n = 8), there were 42 AA donors and 115 Bx donors, respectively. Three-year DFS, OS, relapse, and GRFS for the entire cohort were 58% (95% confidence interval [CI], 50% to 66%), 67% (95% CI, 59% to 74%), 26% (95% CI, 19% to 33%), and 27% (95% CI, 19% to 35%), respectively. The cumulative incidence of grade II-IV aGVHD at 100 days was 36% (95% CI, 27% to 44%), and that of cGVHD at 1 year was 23% (95% CI, 17% to 30%). There were no differences between AA donors and Bx donors for any recipient survival outcomes. The risk of grade II-IV aGVHD was lower in patients with donors with a B content score of ≥2 (hazard ratio [HR], 0.46; 95% CI, 0.26 to 0.83; P = .01), an activating KIR content score of >3 (HR, 0.52; 95% CI, 0.29 to 0.95; P = .032), centromeric A/B score (HR, 0.57; 95% CI, 033 to 0.98; P = .041), and telomeric A/B score (HR, 0.58; 95% CI, 0.34 to 1.00; P = .048). To our knowledge, this is the first study analyzing the association of NK cell determinants and outcomes in JMML HCT recipients. This study identifies potential benefits of donor KIR-B genotypes in reducing aGVHD. Our findings warrant further study of the role of NK cells in enhancing the graft-versus-leukemia effect via recognition of JMML blasts.

Prolonged thrombocytopenia in a neonate with Noonan syndrome: a case report

We report a case of a Chinese neonate who was diagnosed with Noonan syndrome and had persistent, self-limited thrombocytopenia. The neonate was admitted to the Neonatology Department 20 minutes after birth because of respiratory distress. From birth until 2 months of age, platelet values fluctuated between approximately 6 and 30 × 10⁹/L. There was no intracranial hemorrhage. However, the child had a transient hypocalcemic seizure and fever. We excluded thrombocytopenia caused by perinatal asphyxia, immune thrombocytopenia, fetomaternal alloimmune thrombocytopenia, juvenile myelomonocytic leukemia, and chromosome 13, 18, and 21 trisomy syndromes. Despite treatment with anti-infective agents and transfusion of platelets and immunoglobulin, the platelet count did not return to the normal range. Genetic testing confirmed a PTPN11 gene mutation, which led to the diagnosis of Noonan syndrome. At 3 months of age, the platelet count gradually increased without intervention and returned to the normal range by 6 months. We speculate that the thrombocytopenia in this case was closely related to Noonan syndrome.

FAS and RAS related Apoptosis defects: From autoimmunity to leukemia

The human adaptive immune system recognizes almost all the pathogens that we encounter and all the tumor antigens that may arise during our lifetime. Primary immunodeficiencies affecting lymphocyte development or function therefore lead to severe infections and tumor susceptibility. Furthermore, the fact that autoimmunity is a frequent feature of primary immunodeficiencies reveals a third function of the adaptive immune system: its self-regulation. Indeed, the generation of a broad repertoire of antigen receptors (via a unique strategy of random somatic rearrangements of gene segments in T cell and B cell receptor loci) inevitably creates receptors with specificity for self-antigens and thus leads to the presence of autoreactive lymphocytes. There are many different mechanisms for controlling the emergence or action of autoreactive lymphocytes, including clonal deletion in the primary lymphoid organs, receptor editing, anergy, suppression of effector lymphocytes by regulatory lymphocytes, and programmed cell death. Here, we review the genetic defects affecting lymphocyte apoptosis and that are associated with lymphoproliferation and autoimmunity, together with the role of somatic mutations and their potential involvement in more common autoimmune diseases.

Rigosertib ameliorates the effects of oncogenic KRAS signaling in a murine model of myeloproliferative neoplasia

Aberrant signaling triggered by oncogenic or hyperactive RAS proteins contributes to the malignant phenotypes in a significant percentage of myeloid malignancies. Of these, juvenile myelomonocytic leukemia (JMML), an aggressive childhood cancer, is largely driven by mutations in RAS genes and those that encode regulators of these proteins. The Mx1-cre kras^+/G12D mouse model mirrors several key features of this disease and has been used extensively to determine the utility and mechanism of small molecule therapeutics in the context of RAS-driven myeloproliferative disorders. Treatment of disease-bearing KRAS^G12D mice with rigosertib (RGS), a small molecule RAS mimetic that is in phase II and III clinical trials for MDS and AML, decreased the severity of leukocytosis and splenomegaly and extended their survival. RGS also increased the frequency of HSCs and rebalanced the ratios of myeloid progenitors. Further analysis of KRAS^G12D HSPCs in vitro revealed that RGS suppressed hyperproliferation in response to GM-CSF and inhibited the phosphorylation of key RAS effectors. Together, these data suggest that RGS might be of clinical benefit in RAS-driven myeloid disorders.

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.

[Clinical and laboratory characteristics of juvenile myelomonocytic leukemia]

OBJECTIVE

To study the clinical and laboratory characteristics of juvenile myelomonocytic leukemia (JMML).

METHODS

The clinical characteristics and laboratory results were retrospectively analyzed in 10 children with newly diagnosed JMML. They were compared with those of 28 children with myelodysplastic syndrome (MDS) and 44 children with chronic myeloid leukemia (CML).

RESULTS

Compared with the children with CML or MDS, the children with JMML had significantly higher rates of skin rashes, ecchymosis, and lymphadenectasis, a significantly lower serum cholinesterase (ChE) level, and a significantly higher fetal hemoglobin level (P&lt;0.05). The white blood cell count of children with JMML was significantly higher than that of children with MDS, but significantly lower than that of children with CML (P&lt;0.05). In addition, the myeloid/erythroid ratio and rate of dyshaematopoiesis were significantly lower in children with JMML than those in children with CML or MDS. The children with JMML had a significantly higher expression of mature monocyte marker CD14 than those with CML or MDS (P&lt;0.05). The levels of myeloid markers CD33, CD11b, CD13, and CD15 in children with JMML were significantly higher than those in children with MDS, but significantly lower than those in children with CML (P&lt;0.05). The levels of CD2 and CD7 in children with JMML were higher than those in children with CML, but lower than those in children with MDS (P&lt;0.05).

CONCLUSIONS

Skin rashes, ecchymosis, lymphadenectasis, and ChE reduction are more common in children with JMML than in those with CML or MDS, while dyshaematopoiesis is less common. In addition, CD14 level increases significantly in children with JMML.

GM-CSF as a target in inflammatory/autoimmune disease: current evidence and future therapeutic potential

Granulocyte-macrophage colony-stimulating factor (GM-CSF) can be viewed as a pro-inflammatory cytokine rather than as a key regulator of steady state and systemic myelopoiesis. Key aspects of GM-CSF biology need to be clarified such as pro-survival vs activation/differentiation function, its cellular sources, its responsive cell populations, its downstream mediators/pathways, and when GM-CSF is relevant. Striking effects of GM-CSF depletion/deletion in some pre-clinical autoimmune/inflammation models have been reported. Systemic effects of administered GM-CSF are not necessarily informative about its local blockade in disease. Recent clinical RA trials, particularly Phase II trials with mavrilimumab (anti-GM-CSFRα Ab), show rapid and impressive efficacy with no significant adverse effects. Larger and longer trials targeting GM-CSF are needed and with careful monitoring of unwanted side effects. This review summarizes the most recent information on these topics.