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

Screening and interventional strategies for the late effects and toxicities of hematological malignancy treatments in pediatric survivors

INTRODUCTION

Advancements in pediatric cancer treatment have increased patient survival rates; however, childhood cancer survivors may face long-term health challenges due to treatment-related effects on organs. Regular post-treatment surveillance and early intervention are crucial for improving the survivors' quality of life and long-term health outcomes. The present paper highlights the significance of late effects in childhood cancer survivors, particularly those with hematologic malignancies, stressing the importance of a vigilant follow-up approach to ensure better overall well-being.

AREAS COVERED

This article provides an overview of the treatment history of childhood leukemia and lymphoma as well as outlines the emerging late effects of treatments. We discuss the various types of these complications and their corresponding risk factors.

EXPERT OPINION

Standardizing survivorship care in pediatric cancer aims to improve patient well-being by optimizing their health outcomes and quality of life. This involves early identification and intervention of late effects, requiring collaboration among specialists, nurses, and advocates, and emphasizing data sharing and international cooperation.

Droplet digital PCR: An effective method for monitoring and prognostic evaluation of minimal residual disease in JMML

Juvenile myelomonocytic leukaemia (JMML) is a rare myeloproliferative neoplasm requiring haematopoietic stem cell transplantation (HSCT) for potential cure. Relapse poses a significant obstacle to JMML HSCT treatment, as the lack of effective minimal residual disease (MRD)-monitoring methods leads to delayed interventions. This retrospective study utilized the droplet digital PCR (ddPCR) technique, a highly sensitive nucleic acid detection and quantification technique, to monitor MRD in 32 JMML patients. The results demonstrated that ddPCR detected relapse manifestations earlier than traditional methods and uncovered molecular insights into JMML MRD dynamics. The findings emphasized a critical 1- to 3-month window post-HSCT for detecting molecular relapse, with 66.7% (8/12) of relapses occurring within this period. Slow MRD clearance post-HSCT was observed, as 65% (13/20) of non-relapse patients took over 6 months to achieve ddPCR-MRD negativity. Furthermore, bone marrow ddPCR-MRD levels at 1-month post-HSCT proved to be prognostically significant. Relapsed patients exhibited significantly elevated ddPCR-MRD levels at this time point (p = 0.026), with a cut-off of 0.465% effectively stratifying overall survival (p = 0.007), event-free survival (p = 0.035) and cumulative incidence of relapse (p = 0.035). In conclusion, this study underscored ddPCR's superiority in JMML MRD monitoring post-HSCT. It provided valuable insights into JMML MRD dynamics, offering guidance for the effective management of JMML.

Efficacy and safety of azacitidine in pediatric patients with newly diagnosed advanced myelodysplastic syndromes before hematopoietic stem cell transplantation in the AZA-JMML-001 trial

Here we report efficacy, pharmacokinetics, and safety data obtained in treatment-naive, pediatric patients with newly diagnosed advanced MDS receiving azacitidine in the AZA-JMML-001 study. The primary endpoint was response rate (proportion of patients with complete response [CR], partial response [PR], or marrow CR, sustained for ≥4 weeks). Of the 10 patients enrolled, one had an unconfirmed marrow CR and none had confirmed responses after three cycles; the study was therefore closed after stage 1. Azacitidine was well tolerated. The lack of efficacy of azacitidine in pediatric patients with newly diagnosed advanced MDS highlights the need for effective new treatments in these patients.

Phenotypic profiling of CD34+ cells by advanced flow cytometry improves diagnosis of juvenile myelomonocytic leukemia

Diagnostic criteria for juvenile myelomonocytic leukemia (JMML) are currently well defined, however in some patients diagnosis still remains a challenge. Flow cytometry is a well established tool for diagnosis and follow-up of hematological malignancies, nevertheless it is not routinely used for JMML diagnosis. Herewith, we characterized the CD34+ hematopoietic precursor cells collected from 31 children with JMML using a combination of standardized EuroFlow antibody panels to assess the ability to discriminate JMML cells from normal/reactive bone marrow cell as controls (n=29) or from cells of children with other hematological diseases mimicking JMML (n=9). CD34+ precursors in JMML showed markedly reduced B-cell and erythroid-committed precursors compared to controls, whereas monocytic and CD7+ lymphoid precursors were significantly expanded. Moreover, aberrant immunophenotypes were consistently present in CD34+ precursors in JMML, while they were virtually absent in controls. Multivariate logistic regression analysis showed that combined assessment of the number of CD34+CD7+ lymphoid precursors and CD34+ aberrant precursors or erythroid precursors had a great potential in discriminating JMMLs versus controls. Importantly our scoring model allowed highly efficient discrimination of truly JMML versus patients with JMML-like diseases. In conclusion, we show for the first time that CD34+ precursors from JMML patients display a unique immunophenotypic profile which might contribute to a fast and accurate diagnosis of JMML worldwide by applying an easy to standardize single eight-color antibody combination.

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.

[Juvenile myelomonocytic leukemia and pediatric myelodysplastic syndromes]

Juvenile myelomonocytic leukemia (JMML) and myelodysplastic syndromes (MDS) of children are rare and aggressive diseases. They both have the particularity of being very frequently associated with an underlying predisposition syndrome, which must be systematically investigated by meticulous clinical exam completed by molecular analysis on fibroblasts, in order to guarantee the best therapeutic management. New generation sequencing techniques have made it possible to better define the landscape of constitutional predisposing pathologies, to understand the clonal evolution that leads to the development of hematological malignancies and to identify new prognostic markers. In these two diseases, the only curative treatment is allogeneic hematopoietic stem cell transplantation, for which the appropriate timeframe, the type of donor and the conditioning must be decided in consultation with the expert teams in each entity.

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.

Epigenetic Profiling of PTPN11 Mutant JMML Hematopoietic Stem and Progenitor Cells Reveals an Aberrant Histone Landscape

Juvenile myelomonocytic leukemia (JMML) is a deadly pediatric leukemia driven by RAS pathway mutations, of which >35% are gain-of-function in PTPN11. Although DNA hypermethylation portends severe clinical phenotypes, the landscape of histone modifications and chromatin profiles in JMML patient cells have not been explored. Using global mass cytometry, Epigenetic Time of Flight (EpiTOF), we analyzed hematopoietic stem and progenitor cells (HSPCs) from five JMML patients with PTPN11 mutations. These data revealed statistically significant changes in histone methylation, phosphorylation, and acetylation marks that were unique to JMML HSPCs when compared with healthy controls. Consistent with these data, assay for transposase-accessible chromatin with sequencing (ATAC-seq) analysis revealed significant alterations in chromatin profiles at loci encoding post-translational modification enzymes, strongly suggesting their mis-regulated expression. Collectively, this study reveals histone modification pathways as an additional epigenetic abnormality in JMML patient HSPCs, thereby uncovering a new family of potential druggable targets for the treatment of JMML.

Lineage Plasticity and Stemness Phenotypes in Prostate Cancer: Harnessing the Power of Integrated "Omics" Approaches to Explore Measurable Metrics

Prostate cancer (PCa), the most frequent and second most lethal cancer type in men in developed countries, is a highly heterogeneous disease. PCa heterogeneity, therapy resistance, stemness, and lethal progression have been attributed to lineage plasticity, which refers to the ability of neoplastic cells to undergo phenotypic changes under microenvironmental pressures by switching between developmental cell states. What remains to be elucidated is how to identify measurements of lineage plasticity, how to implement them to inform preclinical and clinical research, and, further, how to classify patients and inform therapeutic strategies in the clinic. Recent research has highlighted the crucial role of next-generation sequencing technologies in identifying potential biomarkers associated with lineage plasticity. Here, we review the genomic, transcriptomic, and epigenetic events that have been described in PCa and highlight those with significance for lineage plasticity. We further focus on their relevance in PCa research and their benefits in PCa patient classification. Finally, we explore ways in which bioinformatic analyses can be used to determine lineage plasticity based on large omics analyses and algorithms that can shed light on upstream and downstream events. Most importantly, an integrated multiomics approach may soon allow for the identification of a lineage plasticity signature, which would revolutionize the molecular classification of PCa patients.

Layered immunity and layered leukemogenicity: Developmentally restricted mechanisms of pediatric leukemia initiation

Hematopoietic stem cells (HSCs) and multipotent progenitor cells (MPPs) arise in successive waves during ontogeny, and their properties change significantly throughout life. Ontological changes in HSCs/MPPs underlie corresponding changes in mechanisms of pediatric leukemia initiation. As HSCs and MPPs progress from fetal to neonatal, juvenile and adult stages of life, they undergo transcriptional and epigenetic reprogramming that modifies immune output to meet age-specific pathogenic challenges. Some immune cells arise exclusively from fetal HSCs/MPPs. We propose that this layered immunity instructs cell fates that underlie a parallel layered leukemogenicity. Indeed, some pediatric leukemias, such as juvenile myelomonocytic leukemia, myeloid leukemia of Down syndrome, and infant pre-B-cell acute lymphoblastic leukemia, are age-restricted. They only present during infancy or early childhood. These leukemias likely arise from fetal progenitors that lose competence for transformation as they age. Other childhood leukemias, such as non-infant pre-B-cell acute lymphoblastic leukemia and acute myeloid leukemia, have mutation profiles that are common in childhood but rare in morphologically similar adult leukemias. These differences could reflect temporal changes in mechanisms of mutagenesis or changes in how progenitors respond to a given mutation at different ages. Interactions between leukemogenic mutations and normal developmental switches offer potential targets for therapy.

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.

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.

LncRNA NR2F1-AS1 was involved in azacitidine resistance of THP-1 cells by targeting IGF1 with miR-483-3p

BACKGROUND

The long noncoding RNAs' (lncRNAs) effect on cancer therapy resistance by targeting microRNA (miRNA) in the regulation of drug resistance genes has attracted more and more attention. This study attempted to explore the mechanism of "lncRNA NR2F1-AS1/miR-483-3p/IGF1″ axis in azacitidine resistance of THP-1 cells.

METHODS

THP-1 cells were treated with azacitidine to construct THP1-Aza cells. Cell number and morphological changes were observed by a microscope. CCK8, flow cytometry and transwell were used to detect cell proliferation, apoptosis, cycle, invasion and migration. The targeting relationships between NR2F1-AS1 and miR-483-3p, IGF1 and miR-483-3p were analyzed by dual-luciferase, respectively. RIP assay was applied to verify the interaction between NR2F1-AS1 and miR-483-3p. The relative mRNA expression levels of miR-483-3p, AKT1, PI3K, NR2F1-AS1 and IGF1 were detected by qRT-PCR. PI3K, p-PI3K, AKT, p-AKT and IGF1 protein expression were detected by western blot.

RESULTS

Compared with THP-1 cells, NR2F1-AS1 and IGF1 were highly expressed in THP1-Aza cells, and the miR-483-3p expression was significantly decreased in THP1-Aza cells. Knockdown of NR2F1-AS1 increased apoptosis and G1 phase, and reduced cells growth, invasion and migration ability of THP1-Aza cells. Dual-luciferase demonstrated that NR2F1-AS1 could bind to miR-483-3p, and miR-483-3p could bind to IGF1. RIP assay verified the interaction between NR2F1-AS1 and miR-483-3p. Compared with the si-NR2F1-AS1 group, miR-483-3p inhibitor or oe-IGF1 treatment reduced the apoptosis and cell cycle, and increased the cell growth, invasion and migration ability of THP-1-Aza cells.

CONCLUSION

LncRNA NR2F1-AS1 affects the sensitivity of THP-1 cells to azacitidine resistance by regulating the miR-483-3p/IGF1 axis, which may be a potential target for the treatment of acute monocytic leukemia.

Short-term efficacy of decitabine-based therapy in JMML: a retrospective study from a single center in China

Juvenile myelomonocytic leukemia (JMML) is an aggressive pediatric myeloproliferative disease, and newly diagnosed patients frequently cannot tolerate hematopoietic stem cell transplantation (HSCT) at diagnosis due to their poor condition. This retrospective analysis aimed to explore the short-term effect of decitabine-dominant therapy on improving the condition of JMML patients before HSCT. The subjects were 10 JMML patients. All patients were treated with decitabine after low-dose chemotherapy with an interval of 4 weeks before bridging to HSCT. The median treatment course was 3 cycles, and the overall response rate (ORR) was 70.0% after one cycle and 71.4% after three cycles. White blood cell (WBC) and monocyte counts were significantly lower after treatment, and spleen volume was also lower, though not significantly lower. The 12 month progression-free survival rate (PFS) was 80.0 ± 12.6%. Decitabine-dominant therapy was beneficial for reducing tumor burden and improving clinical condition.

Allogeneic hematopoietic cell transplantation in patients with juvenile myelomonocytic leukemia in Korea: a report of the Korean Pediatric Hematology-Oncology Group

Juvenile myelomonocytic leukemia (JMML) is a life-threatening myeloproliferative neoplasm. This multicenter study evaluated the characteristics, outcomes, and prognostic factors of allogeneic hematopoietic cell transplantation (HCT) in recipients with JMML who were diagnosed between 2000 and 2019 in Korea. Sixty-eight patients were retrospectively enrolled-28 patients (41.2%) received HCT during 2000-2010 and 40 patients (58.8%) during 2011-2020. The proportion of familial mismatched donors increased from 3.6 to 37.5%. The most common conditioning therapy was changed from Busulfan/Cyclophosphamide-based to Busulfan/Fludarabine-based therapy. The 5-year probabilities of event-free survival (EFS) and overall survival (OS) were 52.6% and 62.3%, respectively. The 5-year incidence of transplant-related mortality was 30.1%. Multivariate analysis revealed that the proportion of hemoglobin F ≥ 40%, abnormal cytogenetics, and matched sibling donors were independent risk factors for a higher relapse rate. Patients whose donor chimerism was below 99% had a significantly higher relapse rate. Better OS and lower treatment-related mortality were observed in patients with chronic graft-versus-host disease (GVHD), whereas grade III or IV acute GVHD was associated with worse EFS. In conclusion, the number of transplant increased along with the increase in alternative donor transplants, nevertheless, similar results were maintained. Alternative donor transplantation should be encouraged.

Cancer epigenetics in clinical practice

Cancer development is driven by the accumulation of alterations affecting the structure and function of the genome. Whereas genetic changes disrupt the DNA sequence, epigenetic alterations contribute to the acquisition of hallmark tumor capabilities by regulating gene expression programs that promote tumorigenesis. Shifts in DNA methylation and histone mark patterns, the two main epigenetic modifications, orchestrate tumor progression and metastasis. These cancer-specific events have been exploited as useful tools for diagnosis, monitoring, and treatment choice to aid clinical decision making. Moreover, the reversibility of epigenetic modifications, in contrast to the irreversibility of genetic changes, has made the epigenetic machinery an attractive target for drug development. This review summarizes the most advanced applications of epigenetic biomarkers and epigenetic drugs in the clinical setting, highlighting commercially available DNA methylation-based assays and epigenetic drugs already approved by the US Food and Drug Administration.

Juvenile Myelomonocytic Leukemia in a Child: A Case Report of Palliative Chemotherapy and Literature Review Applied to Limited Resources Centers

Juvenile myelomonocytic leukemia (JMML) is a rare hematopoietic malignancy in children, with an incidence of 1.2 per million children per year. At this moment, we present a case report and a brief literature review of JMML in a child, primarily focused on its applicability in low-middle income countries. A 3.5-year-old male was referred to our tertiary center due to pallor, enlarging abdomen and neck mass, recurrent fever, and chronic diarrhea. Initial laboratory workup showed hemoglobin of 6.4 g/dl, white blood cell of 315.62 × 103/μL, and platelet of 17 × 103/μL. Blood smears showed 10% suspected blasts, 17% myelocytes, and 17% metamyelocytes with thrombocytopenic crisis. The HbF level was 5.8%. BCR-ABL gene tested negative. The patient was diagnosed with juvenile myelomonocytic leukemia. Considering that HSCT could not be done in our center and lack other financial possibilities to seek treatment abroad, the family agreed to do the palliative treatment. The patient was treated with oral 6-mercaptopurine and subcutaneous cytarabine. Four weeks after receiving 6-mercaptopurine, the white blood cell count decreased to 10.6 × 103/μL and the spleen size was half of the original size. The patient continued chemotherapy until week 15, chemotherapy was stopped, but 16 weeks after the diagnosis of JMML, he developed severe thrombocytopenia, endophthalmitis, and sepsis and passed away. As a conclusion, in JMML cases in developing countries without HSCT, palliative chemotherapy is acceptable, and palliative care is an important aspect.

Targeted therapy in juvenile myelomonocytic leukemia: Where are we now?

Juvenile myelomonocytic leukemia (JMML) is a rare and aggressive clonal neoplasm of early childhood, classified as an overlap myeloproliferative/myelodysplastic neoplasm by the World Health Organization. In 90% of the patients with JMML, typical initiating mutations in the canonical Ras pathway genes NF1, PTPN11, NRAS, KRAS, and CBL can be identified. Hematopoietic stem cell transplantation (HSCT) currently is the established standard of care in most patients, although long-term survival is still only 50-60%. Given the limited therapeutic options and the important morbidity and mortality associated with HSCT, new therapeutic approaches are urgently needed. Hyperactivation of the Ras pathway as disease mechanism in JMML lends itself to the use of targeted therapy. Targeted therapy could play an important role in the future treatment of patients with JMML. This review presents a comprehensive overview of targeted therapies already developed and evaluated in vitro and in vivo in patients with JMML.

Small molecule inhibitors targeting the cancers

Compared with traditional therapies, targeted therapy has merits in selectivity, efficacy, and tolerability. Small molecule inhibitors are one of the primary targeted therapies for cancer. Due to their advantages in a wide range of targets, convenient medication, and the ability to penetrate into the central nervous system, many efforts have been devoted to developing more small molecule inhibitors. To date, 88 small molecule inhibitors have been approved by the United States Food and Drug Administration to treat cancers. Despite remarkable progress, small molecule inhibitors in cancer treatment still face many obstacles, such as low response rate, short duration of response, toxicity, biomarkers, and resistance. To better promote the development of small molecule inhibitors targeting cancers, we comprehensively reviewed small molecule inhibitors involved in all the approved agents and pivotal drug candidates in clinical trials arranged by the signaling pathways and the classification of small molecule inhibitors. We discussed lessons learned from the development of these agents, the proper strategies to overcome resistance arising from different mechanisms, and combination therapies concerned with small molecule inhibitors. Through our review, we hoped to provide insights and perspectives for the research and development of small molecule inhibitors in cancer treatment.

Challenges in the interpretation of a germline TERT variant in a patient with juvenile myelomonocytic leukemia

Dyskeratosis congenita (DC) is a bone marrow failure syndrome with extrahematopoietic abnormalities. DC is a paradigmatic telomere biology disorder (TBD) caused by germline mutations in genes responsible for telomere maintenance including TERT. Cryptic TBD is a bone marrow failure syndrome due to premature telomere shortening but without additional symptoms, frequently clinically indistinguishable from severe aplastic anemia (SAA) or hypoplastic myelodysplastic syndrome. We present the complex diagnostic pathway in a boy with a rare germline p.Thr726Met TERT variant with previous reports of SAA association and compromised enzymatic function who presented with juvenile myelomonocytic leukemia, which is a rare myelodysplastic/myeloproliferative neoplasm of childhood.

Genomic and Epigenomic Landscape of Juvenile Myelomonocytic Leukemia

Simple Summary

Juvenile myelomonocytic leukemia (JMML) is a rare pediatric myelodysplastic/myeloproliferative neoplasm characterized by the constitutive activation of the RAS pathway. In spite of the recent progresses in the molecular characterization of JMML, this disease is still a clinical challenge due to its heterogeneity, difficult diagnosis, poor prognosis, and the lack of curative treatment options other than hematopoietic stem cell transplantation (HSCT). In this review, we will provide a detailed overview of the genetic and epigenetic alterations occurring in JMML, and discuss their clinical relevance in terms of disease prognosis and risk of relapse after HSCT. We will also present the most recent advances on novel preclinical and clinical therapeutic approaches directed against JMML molecular targets. Finally, we will outline future research perspectives to further explore the oncogenic mechanism driving JMML leukemogenesis and progression, with special attention to the application of single-cell next-generation sequencing technologies.

Abstract

Juvenile myelomonocytic leukemia (JMML) is a rare myelodysplastic/myeloproliferative neoplasm of early childhood. Most of JMML patients experience an aggressive clinical course of the disease and require hematopoietic stem cell transplantation, which is currently the only curative treatment. JMML is characterized by RAS signaling hyperactivation, which is mainly driven by mutations in one of five genes of the RAS pathway, including PTPN11, KRAS, NRAS, NF1, and CBL. These driving mutations define different disease subtypes with specific clinico-biological features. Secondary mutations affecting other genes inside and outside the RAS pathway contribute to JMML pathogenesis and are associated with a poorer prognosis. In addition to these genetic alterations, JMML commonly presents aberrant epigenetic profiles that strongly correlate with the clinical outcome of the patients. This observation led to the recent publication of an international JMML stratification consensus, which defines three JMML clinical groups based on DNA methylation status. Although the characterization of the genomic and epigenomic landscapes in JMML has significantly contributed to better understand the molecular mechanisms driving the disease, our knowledge on JMML origin, cell identity, and intratumor and interpatient heterogeneity is still scarce. The application of new single-cell sequencing technologies will be critical to address these questions in the future.

Immunophenotypic changes in juvenile myelomonocytic leukaemia after treatment with hypomethylating agent: Do they help to evaluate dept of response?

5-Azacitidine has been used before stem cell transplantation in juvenile myelomonocytic leukaemia (JMML) patients. Recently, we have described immunophenotypic features in JMML at diagnosis. Here, our aim was to examine the changes in the immunophenotypic features during azacitidine treatment, correlating it with clinical response. Patients treated with 5-azacitidine were evaluated at diagnosis and after three and six cycles of medication. Among 32 patients entering the study, 28 patients were examined after three cycles and 25 patients after six. Patients showed a reduction in CD34/CD117⁺ cells: median 3.35% at diagnosis, 2.8% after three cycles and 1.63% after six. B-cell progenitors were decreased at diagnosis and decreased after treatment. Monocytes decreased: 11.91% to 6.4% and 4.18% respectively. Complete response was associated with increase in classical monocytes. T lymphocytes, reduced at diagnosis, increased in patients responding to 5-azacitidine. Immunophenotypic aberrancies including expression of CD7 in myeloid progenitors remained after treatment. This feature was associated with a worse response to treatment, as well as presence of NF1. Immunophenotyping was feasible in all patients. Clinical response was associated with a decrease of myeloid progenitors and monocytes and a rise in T lymphocytes although phenotypic aberrancies persisted. The largest effect was observed after three cycles.

Role of CBL Mutations in Cancer and Non-Malignant Phenotype

Simple Summary

CBL mutations are progressively being described as involved in different clinical manifestations. Somatic CBL mutations can be found in different type of cancer. The clinical spectrum of germline mutations configures the so-called CBL syndrome, a cancer-predisposing condition that includes multisystemic involvement characterized by variable phenotypic expression and expressivity. In this review we provide an up-to-date review of the clinical manifestation of CBL mutations and of the molecular mechanisms in which CBL exerts its pathogenic role.

Abstract

CBL plays a key role in different cell pathways, mainly related to cancer onset and progression, hematopoietic development and T cell receptor regulation. Somatic CBL mutations have been reported in a variety of malignancies, ranging from acute myeloid leukemia to lung cancer. Growing evidence have defined the clinical spectrum of germline CBL mutations configuring the so-called CBL syndrome; a cancer-predisposing condition that also includes multisystemic involvement characterized by variable phenotypic expression and expressivity. This review provides a comprehensive overview of the molecular mechanisms in which CBL exerts its function and describes the clinical manifestation of CBL mutations in humans.