BH3 mimetics and azacitidine show synergistic effects on juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is an aggressive hematopoietic disorder of infancy and early childhood driven by constitutively active RAS signaling and characterized by abnormal proliferation of the granulocytic-monocytic blood cell lineage. Most JMML patients require hematopoietic stem cell transplantation for cure, but the risk of relapse is high for some JMML subtypes. Azacitidine was shown to effectively reduce leukemic burden in a subset of JMML patients. However, variable response rates to azacitidine and the risk of drug resistance highlight the need for novel therapeutic approaches. Since RAS signaling is known to interfere with the intrinsic apoptosis pathway, we combined various BH3 mimetic drugs with azacitidine in our previously established patient-derived xenograft model. We demonstrate that JMML cells require both MCL-1 and BCL-XL for survival, and that these proteins can be effectively targeted by azacitidine and BH3 mimetic combination treatment. In vivo azacitidine acts via downregulation of antiapoptotic MCL-1 and upregulation of proapoptotic BH3-only. The combination of azacitidine with BCL-XL inhibition was superior to BCL-2 inhibition in eliminating JMML cells. Our findings emphasize the need to develop clinically applicable MCL-1 or BCL-XL inhibitors in order to enable novel combination therapies in JMML refractory to standard therapy.

Allogeneic Hematopoietic Cell Transplantation for Juvenile Myelomonocytic Leukemia with a Busulfan, Fludarabine, and Melphalan Regimen: JPLSG JMML-11.

Juvenile myelomonocytic leukemia (JMML), which is classified as a myelodysplastic/myeloproliferative neoplasm, is a rare hematologic malignancy of childhood. Most patients with JMML require allogeneic hematopoietic cell transplantation (HCT) as a curative therapy. A Japanese retrospective analysis demonstrated favorable outcomes for a busulfan (BU) + fludarabine (FLU) + melphalan (MEL) regimen, with an overall survival (OS) of 72% and an event-free survival (EFS) of 53%. To further validate the efficacy and safety of this regimen, the Japan Pediatric Leukemia/Lymphoma Study Group (JPLSG) conducted a nationwide prospective study, JMML-11. Between July 2011 and June 2017, 28 patients with newly diagnosed JMML were enrolled in JMML11. Low-dose chemotherapy for tumor control before HCT was recommended, and patients treated with AML-type chemotherapy and azacitidine were excluded. The conditioning regimen comprised i.v. BU, 16 doses administered every 6 h, with dose adjustment based on pharmacokinetic (PK) studies on days -11 to -8; FLU, 30 mg/m2/day or 1 mg/kg/day for patients <10 kg or age <1 year on days -7 to -4; and MEL, 90 mg/m2/day or 3 mg/kg/day for patients <10 kg or <1 year on days -3 to -2. The donor was selected by the physician in charge. A family donor was available for 7 patients (3 HLA-matched siblings, 3 HLA-1-antigen mismatched parents, and 1 haploidentical father). Overall, 21 patients received grafts from unrelated donors, including 8 HLA-matched donors and 13 HLA-mismatched donors. The graft source was related bone marrow (BM) for 7 patients, unrelated BM for 14 patients, and unrelated cord blood for 7 patients. Neutrophil engraftment was achieved in 21 of 28 patients (75%), with a median of 20.5 days (range, 11 to 39 days) after transplantation. The 3-year OS, 3-year EFS, 3-year relapse rate, and 3-year transplantation-related mortality were 63% (95% confidence interval [CI], 42% to 78%), 52% (95% CI, 32% to 69%), 18% (95% CI, 6% to 34%), and 21% (95% CI, 9% to 38%), respectively. WBC count before the conditioning regimen (≥7.0 × 109/L) was significantly associated with inferior EFS and OS. Body surface area ≥.5 m2, spleen size <4 cm before conditioning, and HLA-matched unrelated BM donors were significantly associated with better OS. Adverse effects related to the conditioning regimen included febrile neutropenia (86%), diarrhea (39%), hypoxemia (21%), and mucositis (18%). BU-associated toxicity, including sinusoidal obstruction syndrome (SOS) and thrombotic microangiopathy (TMA), occurred in 7 patients (25%; SOS, n = 6; TMA, n = 2). Retrospective analysis of PK data after the first BU dose in 23 patients, including 6 with SOS and 17 without SOS, did not show significant differences between groups. The JMML-11 study confirms the positive results of previous retrospective analyses. BU+FLU+MEL might become a standard conditioning regimen for patients with JMML.

Tretinoin Enhances the Effects of Chemotherapy in Juvenile Myelomonocytic Leukemia Using an Ex Vivo Drug Sensitivity Assay.

PURPOSE: Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric malignancy with myelodysplastic and myeloproliferative features. Curative treatment is restricted to hematopoietic stem-cell transplantation. Fludarabine combined with cytarabine (FLA) and 5-azacitidine (AZA) monotherapy are commonly used pre-transplant therapies. Here, we present a drug screening strategy using a flow cytometry-based precision medicine platform to identify potential additional therapeutic vulnerabilities. METHODS: We screened 120 dual- and 10 triple-drug combinations (DCs) on peripheral blood (n = 21) or bone marrow (n = 6) samples from 27 children with JMML to identify DCs more effectively reducing leukemic cells than the DCs' components on their own. If fewer leukemic cells survived a DC ex vivo treatment compared with that DC's most effective component alone, the drug effect was referred to as cooperative. The difference between the two resistant fractions is the effect size. RESULTS: We identified 26 dual- and one triple-DC more effective than their components. The differentiation agent tretinoin (TRET; all-trans retinoic acid) reduced the resistant fraction of FLA in 19/21 (90%) samples (decrease from 15% [2%-61%] to 11% [2%-50%] with a mean effect size of 3.8% [0.5%-11%]), and of AZA in 19/25 (76%) samples (decrease from 69% [34%-100+%] to 47% [17%-83%] with a mean effect size of 16% [0.3%-40%]). Among the resistant fractions, the mean proportion of CD38+ cells increased from 7% (0.03%-25%; FLA) to 17% (0.3%-38%; FLA + TRET) or from 10% (0.2%-31%; AZA) to 51% (0.8%-88%; AZA + TRET). CONCLUSION: TRET enhanced the effects of FLA and AZA in ex vivo assays with primary JMML samples.

Azacitidine (Vidaza®) in Pediatric Patients with Relapsed Advanced MDS and JMML: Results of a Phase I/II Study by the ITCC Consortium and the EWOG-MDS Group (Study ITCC-015).

BACKGROUND: Advanced myelodysplastic syndrome (MDS) and juvenile myelomonocytic leukemia (JMML) are rare hematological malignancies in children. A second allograft is recommended if a relapse occurs after hematopoietic stem cell transplantation, but the outcome is poor. OBJECTIVE: We conducted a phase I/II multicenter study to evaluate the safety, pharmacokinetics, and activity of azacitidine in children with relapsed MDS/JMML prior to the second hematopoietic stem cell transplantation. METHODS: Patients enrolled from June 2013 to March 2019 received azacitidine intravenously/subcutaneously once daily on days 1-7 of a 28-day cycle. The MDS and JMML cohorts followed a two-stage design separately, with a safety run-in for JMML. Response and safety data were used to evaluate efficacy and establish the recommended dose. Pharmacokinetics was also analyzed. The study closed prematurely because of low recruitment. RESULTS: Six patients with MDS and four patients with JMML received a median of three and five cycles, respectively. Azacitidine 75 mg/m2 was well tolerated and plasma concentration-time profiles were similar to observed in adults. The most prevalent grade 3-4 adverse event was myelotoxicity. No responses were seen in patients with MDS, but 83% achieved stable disease; four patients underwent an allotransplant. Overall response rate in the JMML cohort was 75% (two complete responses; one partial response) and all responders underwent hematopoietic stem cell transplantation. One-year overall survival was 67% (95% confidence interval 38-100) in MDS and 50% (95% confidence interval 19-100) in JMML. CONCLUSIONS: Azacitidine 75 mg/m2 prior to a second hematopoietic stem cell transplantation is safe in children with relapsed MDS/JMML. Although the long-term advantage remains to be assessed, this study suggests that azacitidine is an efficacious option for relapsed JMML. CLINICAL TRIAL REGISTRATION: EudraCT 2010-022235-10.

Sunitinib selectively targets leukemogenic signaling of mutant SHP2 in juvenile myelomonocytic leukemia.

Leukemogenic SHP2 mutations occur in 35% of patients with juvenile myelomonocytic leukemia (JMML), a hematopoietic malignancy with poor response to cytotoxic chemotherapy. Novel therapeutic strategies are urgently needed for patients with JMML. Previously, we established a novel cell model of JMML with HCD-57, a murine erythroleukemia cell line that depends on EPO for survival. SHP2-D61Y or -E76K drove the survival and proliferation of HCD-57 in absence of EPO. In this study, we identified sunitinib as a potent compound to inhibit SHP2-mutant cells by screening a kinase inhibitor library with our model. We used cell viability assay, colony formation assay, flow cytometry, immunoblotting, and a xenograft model to evaluate the effect of sunitinib against SHP2-mutant leukemia cells in vitro and in vivo. The treatment of sunitinib selectively induced apoptosis and cell cycle arrest in mutant SHP2-transformed HCD-57, but not parental cells. It also inhibited cell viability and colony formation of primary JMML cells with mutant SHP2, but not bone marrow mononuclear cells from healthy donors. Immunoblotting showed that the treatment of sunitinib blocked the aberrantly activated signals of mutant SHP2 with deceased phosphorylation levels of SHP2, ERK, and AKT. Furthermore, sunitinib effectively reduced tumor burdens of immune-deficient mice engrafted with mutant-SHP2 transformed HCD-57. Our data demonstrated that sunitinib selectively inhibited SHP2-mutant leukemia cells, which could serve as an effective therapeutic strategy for SHP2-mutant JMML in the future.

Response to chemotherapy in juvenile myelomonocytic leukemia and its clinical implications for survival: A retrospective registry-based study of the Korean Pediatric Hematology-Oncology Group.

Juvenile myelomonocytic leukemia (JMML) is a life-threatening myeloproliferative neoplasm. The chemotherapeutic effect on survival remains unclear, and feasible standardized response criteria are yet to be established. We aimed to evaluate the chemotherapeutic response and its effect on survival in patients with JMML. A retrospective registry was reviewed for children diagnosed with JMML between 2000 and 2019. Response was assessed according to the criteria proposed by the International JMML Symposium in 2007 (criteria I) and the updated version in 2013 with its modifications (criteria II). A total of 73 patients were included in this study. Complete response (CR) rates were 46.6% and 28.8% using the criteria I and criteria II, respectively. A platelet count ≥ 40 × 109/L at diagnosis was associated with higher CR rates using the criteria II. Patients with criteria I-based CR had a better overall survival (OS) than those without CR (81.1% vs. 49.1% at 5 years). Patients with criteria II-based CR showed better OS (85.7% vs. 55.5% at 5 years) and event-free survival (EFS) (71.1% vs. 44.7% at 5 years) than those without CR. Additionally, a trend toward better EFS was observed in patients with criteria II-based CR than in those with criteria I-based CR but without criteria II-based CR (71.1% vs. 53.8% at 5 years). Chemotherapeutic response is associated with better survival outcomes. Along with splenomegaly, the addition of platelet count recovery, existence of extramedullary leukemic infiltration, and more stringent leukocyte counts to the response criteria allows for a more sensitive prediction of survival outcomes.

Potential clinical use of azacitidine and MEK inhibitor combination therapy in PTPN11-mutated juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) is a rare myeloproliferative neoplasm of childhood. The molecular hallmark of JMML is hyperactivation of the Ras/MAPK pathway with the most common cause being mutations in the gene PTPN11, encoding the protein tyrosine phosphatase SHP2. Current strategies for treating JMML include using the hypomethylating agent, 5-azacitidine (5-Aza) or MEK inhibitors trametinib and PD0325901 (PD-901), but none of these are curative as monotherapy. Utilizing an Shp2E76K/+ murine model of JMML, we show that the combination of 5-Aza and PD-901 modulates several hematologic abnormalities often seen in JMML patients, in part by reducing the burden of leukemic hematopoietic stem and progenitor cells (HSC/Ps). The reduced JMML features in drug-treated mice were associated with a decrease in p-MEK and p-ERK levels in Shp2E76K/+ mice treated with the combination of 5-Aza and PD-901. RNA-sequencing analysis revealed a reduction in several RAS and MAPK signaling-related genes. Additionally, a decrease in the expression of genes associated with inflammation and myeloid leukemia was also observed in Shp2E76K/+ mice treated with the combination of the two drugs. Finally, we report two patients with JMML and PTPN11 mutations treated with 5-Aza, trametinib, and chemotherapy who experienced a clinical response because of the combination treatment.

Transcriptomic Signatures of Hypomethylating Agent Failure in Myelodysplastic Syndromes and Chronic Myelomonocytic Leukemia.

Hypomethylating agents (HMAs) are the standard of care for myelodysplastic syndromes (MDS) and chronic myelomonocytic leukemia (CMML). HMA treatment failure is a major clinical problem and its mechanisms are poorly characterized. We performed RNA sequencing in CD34+ bone marrow stem hematopoietic stem and progenitor cells (BM-HSPCs) from 51 patients with CMML and MDS before HMA treatment and compared transcriptomic signatures between responders and nonresponders. We observed very few genes with significant differential expression in HMA non-responders versus responders, and the commonly altered genes in non-responders to both azacitidine (AZA) and decitabine (DAC) treatments were immunoglobulin genes. Gene set analysis identified 78 biological pathways commonly altered in non-responders to both treatments. Among these, we determined that the γ-aminobutyric acid (GABA) receptor signaling significantly affected hematopoiesis in both human BM-HSPCs and mice, indicating that the transcriptomic signatures identified here could serve as candidate biomarkers and therapeutic targets for HMA failure in MDS and CMML.

Drug Receives New Indication for Juvenile Myelomonocytic Leukemia.

Azacitidine (Vidaza) is now approved to treat juvenile myelomonocytic leukemia, a rare form of blood cancer mostly affecting children under four years of age.

Myeloid leukemoid reaction after initial azacitidine therapy for chronic myelomonocytic leukemia.

The development of myeloid leukocytosis in leukemia patients during antileukemic treatment requires a differential diagnosis between myeloid leukemoid reaction and leukemia progression. We herein report the case of an 80-year-old Japanese man with chronic myelomonocytic leukemia (CMML) who developed marked myeloid leukocytosis (36.3 × 109/L) with 32.5% monocytes and 48% neutrophils about 4 weeks after the initial 5-azacitidine (AZA) treatment. The leukocytosis was unlikely to be attributed to infection and adverse drug reaction. As it resolved in a few days without any interventions, the transient myeloid leukocytosis was confirmed to be a myeloid leukemoid reaction. After four cycles of AZA treatment, leukemic blasts in the bone marrow decreased and the patient became transfusion-independent. Interestingly, levels of serum G-CSF showed a similar trend to the myeloid leukocytosis, while those of serum GM-CSF and IL-17 were undetectable throughout the clinical course, suggesting that a differentiation response to AZA treatment might lead to the myeloid leukemoid reaction. Our case implies that a marked but transient myeloid leukemoid reaction mimicking CMML progression can develop during AZA treatment, which requires careful clinical monitoring and differential diagnosis.

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.

Response to upfront azacitidine in juvenile myelomonocytic leukemia in the AZA-JMML-001 trial.

Allogeneic hematopoietic stem cell transplantation (HSCT) is the only curative therapy for most children with juvenile myelomonocytic leukemia (JMML). Novel therapies controlling the disorder prior to HSCT are needed. We conducted a phase 2, multicenter, open-label study to evaluate the safety and antileukemic activity of azacitidine monotherapy prior to HSCT in newly diagnosed JMML patients. Eighteen patients enrolled from September 2015 to November 2017 were treated with azacitidine (75 mg/m2) administered IV once daily on days 1 to 7 of a 28-day cycle. The primary end point was the number of patients with clinical complete remission (cCR) or clinical partial remission (cPR) after 3 cycles of therapy. Pharmacokinetics, genome-wide DNA-methylation levels, and variant allele frequencies of leukemia-specific index mutations were also analyzed. Sixteen patients completed 3 cycles and 5 patients completed 6 cycles. After 3 cycles, 11 patients (61%) were in cPR and 7 (39%) had progressive disease. Six of 16 patients (38%) who needed platelet transfusions were transfusion-free after 3 cycles. All 7 patients with intermediate- or low-methylation signatures in genome-wide DNA-methylation studies achieved cPR. Seventeen patients received HSCT; 14 (82%) were leukemia-free at a median follow-up of 23.8 months (range, 7.0-39.3 months) after HSCT. Azacitidine was well tolerated and plasma concentration--time profiles were similar to observed profiles in adults. In conclusion, azacitidine monotherapy is a suitable option for children with newly diagnosed JMML. Although long-term safety and efficacy remain to be fully elucidated in this population, these data demonstrate that azacitidine provides valuable clinical benefit to JMML patients prior to HSCT. This trial was registered at www.clinicaltrials.gov as #NCT02447666.

Long non-coding RNAs as novel therapeutic targets in juvenile myelomonocytic leukemia.

Juvenile myelomonocytic leukemia (JMML) treatment primarily relies on hematopoietic stem cell transplantation and results in long-term overall survival of 50-60%, demonstrating a need to develop novel treatments. Dysregulation of the non-coding RNA transcriptome has been demonstrated before in this rare and unique disorder of early childhood. In this study, we investigated the therapeutic potential of targeting overexpressed long non-coding RNAs (lncRNAs) in JMML. Total RNA sequencing of bone marrow and peripheral blood mononuclear cell preparations from 19 untreated JMML patients and three healthy children revealed 185 differentially expressed lncRNA genes (131 up- and 54 downregulated). LNA GapmeRs were designed for 10 overexpressed and validated lncRNAs. Molecular knockdown (≥ 70% compared to mock control) after 24 h of incubation was observed with two or more independent GapmeRs in 6 of them. For three lncRNAs (lnc-THADA-4, lnc-ACOT9-1 and NRIR) knockdown resulted in a significant decrease of cell viability after 72 h of incubation in primary cultures of JMML mononuclear cells, respectively. Importantly, the extent of cellular damage correlated with the expression level of the lncRNA of interest. In conclusion, we demonstrated in primary JMML cell cultures that knockdown of overexpressed lncRNAs such as lnc-THADA-4, lnc-ACOT9-1 and NRIR may be a feasible therapeutic strategy.

Therapeutic effects of andiroba (Carapa guianensis Aubl) oil, compared to low power laser, on oral mucositis in children underwent chemotherapy: A clinical study.

ETHNO-PHARMACOLOGICAL RELEVANCE: The Carapa guianensis Aubl, popularly known as andiroba, is a large tree of the Meliaceae family, commonly found in the Amazon region. The oil extracted from its seeds is recognized in traditional medicine and has high anti-inflammatory and analgesic potential, which are the basic prerequisites for a therapeutic agent that can be used in the treatment of oral mucositis (OM). Moreover, the aforementioned oil has antimicrobial, antiallergic, and parasiticidal actions and is effective in the management of cutaneous and muscular dysfunctions. AIM OF THE STUDY: To evaluate the therapeutic effects of andiroba gel (Carapa guianensis Aubl) on the symptomatology and evolution of OM in children with leukemia who underwent chemotherapy and to compare it to the effects of low power laser. MATERIALS AND METHODS: This randomized, double-blind clinical trial involved 60 patients of both genders with leukemia, with age ranging from six to twelve years. The patients were divided into two study groups: the andiroba group (n = 30) and the laser group (n = 30). The level of pain experienced by the patients was assessed using the Wong-Baker visual analog scale and the degree of severity of OM was assessed using a table, recommended by the World Health Organization, that depicts the degrees of severity of OM. The data obtained were analyzed using the Mann-Whitney test, with statistical significance indicated by a P value less than or equal to 0.05. RESULTS: A statistically significant reduction in the degree of OM was observed on the fourth, fifth, and sixth days and in the pain scores on the second, third, and fourth days in the andiroba group after the manifestation of OM, compared to the laser group. CONCLUSIONS: The use of andiroba oil effectively reduced the severity of OM and relieved pain, which resulted in a decrease in the severity of signs and symptoms in the patients in the andiroba group, compared to the laser group.

Myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes: a focused review.

Myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN) overlap syndromes are unique myeloid neoplasms, with overlapping features of MDS and MPN. They consist of four adult onset entities including chronic myelomonocytic leukemia (CMML), MDS/MPN-ring sideroblasts-thrombocytosis (MDS/MPN-RS-T), BCR-ABL1 negative atypical chronic myeloid leukemia (aCML) and MDS/MPN-unclassifiable (MDS/MPN-U); with juvenile myelomonocytic leukemia (JMML) being the only pediatric onset entity. Among these overlap neoplasms, CMML is the most frequent and is hallmarked by the presence of sustained peripheral blood monocytosis with recurrent mutations involving TET2 (60%), SRSF2 (50%) and ASXL1 (40%); with RAS pathway mutations and JAK2V617F being relatively enriched in proliferative CMML subtypes (WBC ≥13 × 109/L). CMML usually presents in the 7th decade of life, with a male preponderance and is associated with a median overall survival of <36 months. Adverse prognosticators in CMML include increasing age, high WBC, presence of circulating immature myeloid cells, anemia, thrombocytopenia and truncating ASXL1 mutations. While allogeneic stem cell transplantation remains the only curative option, given the late onset of this neoplasm and high frequency of comorbidities, most patients remain ineligible. Hypomethylating agents such as azacitidine, decitabine and oral decitabine/cedazuridine have been US FDA approved for the management of CMML, with overall response rates of 40-50% and complete remission rates of <20%. While these agents epigenetically restore hematopoiesis in a subset of responding patients, they do not impact mutational allele burdens and eventual disease progression to AML remains inevitable. Newer treatment modalities exploiting epigenetic, signaling and splicing abnormalities commonly seen in CMML are much needed.

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.

A Case of Uveitis in a Patient With Juvenile Myelomonocytic Leukemia Successfully Treated With Adalimumab.

Patients with juvenile myelomonocytic leukemia due to germline CBL mutation (10% to 15%) may have a subacute course occasionally associated with autoimmune disorders, which may resemble RAS-associated autoimmune lymphoproliferative disorder. In both conditions, prognosis and standard treatment for autoimmune phenomena remain poorly understood. We report the case of a 7-year-old boy with juvenile myelomonocytic leukemia with severe steroid-dependent uveitis, who did not respond to several therapeutic attempts with immunosuppressant agents, including sirolimus, and was finally successfully treated with adalimumab. This case offers further insight into the management of autoimmune disorders in the context of predisposing genetic conditions.

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.