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.

• MeSH
• azacytidin škodlivé účinky   MeSH
• dítě MeSH
• dospělí MeSH
• juvenilní myelomonocytární leukemie * farmakoterapie   genetika   MeSH
• lidé MeSH
• metylace DNA MeSH
• mutace MeSH
• transplantace hematopoetických kmenových buněk * MeSH
• Check Tag
• dítě MeSH
• dospělí MeSH
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky, fáze II MeSH
• multicentrická studie MeSH
• práce podpořená grantem MeSH

Juvenile myelomonocytic leukemia (JMML) is an aggressive myeloproliferative disorder of early childhood characterized by mutations activating RAS signaling. Established clinical and genetic markers fail to fully recapitulate the clinical and biological heterogeneity of this disease. Here we report DNA methylome analysis and mutation profiling of 167 JMML samples. We identify three JMML subgroups with unique molecular and clinical characteristics. The high methylation group (HM) is characterized by somatic PTPN11 mutations and poor clinical outcome. The low methylation group is enriched for somatic NRAS and CBL mutations, as well as for Noonan patients, and has a good prognosis. The intermediate methylation group (IM) shows enrichment for monosomy 7 and somatic KRAS mutations. Hypermethylation is associated with repressed chromatin, genes regulated by RAS signaling, frequent co-occurrence of RAS pathway mutations and upregulation of DNMT1 and DNMT3B, suggesting a link between activation of the DNA methylation machinery and mutational patterns in JMML.

• MeSH
• biopsie MeSH
• chromatin genetika   metabolismus   MeSH
• dítě MeSH
• DNA-(cytosin-5-)methyltransferasa metabolismus   MeSH
• DNA-(cytosin-5)-methyltransferasa 1 metabolismus   MeSH
• epigenomika MeSH
• juvenilní myelomonocytární leukemie genetika   mortalita   patologie   terapie   MeSH
• kojenec MeSH
• lidé MeSH
• metylace DNA * MeSH
• mutace MeSH
• mutační analýza DNA MeSH
• Noonanové syndrom genetika   patologie   MeSH
• předškolní dítě MeSH
• prognóza MeSH
• prospektivní studie MeSH
• protinádorové látky terapeutické užití   MeSH
• protoonkogenní proteiny c-cbl MeSH
• protoonkogenní proteiny p21(ras) genetika   metabolismus   MeSH
• regulace genové exprese u leukemie MeSH
• signální transdukce genetika   MeSH
• transplantace hematopoetických kmenových buněk MeSH
• tyrosinfosfatasa nereceptorového typu 11 genetika   metabolismus   MeSH
• upregulace MeSH
• Check Tag
• dítě MeSH
• kojenec MeSH
• lidé MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• klinické zkoušky MeSH
• multicentrická studie MeSH
• pozorovací studie MeSH
• práce podpořená grantem MeSH

Aberrant DNA methylation at specific genetic loci is a key molecular feature of juvenile myelomonocytic leukemia (JMML) with poor prognosis. Using quantitative high-resolution mass spectrometry, we identified RASA4 isoform 2, which maps to chromosome 7 and encodes a member of the GAP1 family of GTPase-activating proteins for small G proteins, as a recurrent target of isoform-specific DNA hypermethylation in JMML (51% of 125 patients analyzed). RASA4 isoform 2 promoter methylation correlated with clinical parameters predicting poor prognosis (older age, elevated fetal hemoglobin), with higher risk of relapse after hematopoietic stem cell transplantation, and with PTPN11 mutation. The level of isoform 2 methylation increased in relapsed cases after transplantation. Interestingly, most JMML cases with monosomy 7 exhibited hypermethylation on the remaining RASA4 allele. The results corroborate the significance of epigenetic modifications in the phenotype of aggressive JMML.

• MeSH
• chemorezistence * MeSH
• CpG ostrůvky MeSH
• dítě MeSH
• juvenilní myelomonocytární leukemie diagnóza   metabolismus   patologie   MeSH
• kojenec MeSH
• lidé MeSH
• lidské chromozomy, pár 7 MeSH
• metylace DNA * MeSH
• mladiství MeSH
• monozomie MeSH
• mutace MeSH
• předškolní dítě MeSH
• prognóza MeSH
• promotorové oblasti (genetika) MeSH
• protein - isoformy genetika   metabolismus   MeSH
• proteiny aktivující GTPasu ras genetika   metabolismus   MeSH
• tyrosinfosfatasa nereceptorového typu 11 genetika   metabolismus   MeSH
• umlčování genů MeSH
• Check Tag
• dítě MeSH
• kojenec MeSH
• lidé MeSH
• mladiství MeSH
• mužské pohlaví MeSH
• předškolní dítě MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH