Juvenile Myelomonocytic Leukemia

P1, N=50, Recruiting, Dana-Farber Cancer Institute | Active, not recruiting --> Recruiting | Trial completion date: Dec 2025 --> Dec 2026 | Trial primary completion date: Dec 2025 --> Dec 2026

In this study, we investigate the molecular basis underlying the differential pathogenicity of PTPN11 missense variants and predict the structural consequences of these variants using MutPred2 and AlphaFold2. We find that LOF and GOF variants display distinct functional mechanisms in sodium and DNA binding, and that NS-associated missense variants identified in fetuses with ultrasound-detected anomalies and familiar cases are more likely to be pathogenic.

CN-LOH was confirmed by single nucleotide polymorphism array. This patient presented with an aggressive clinical course and required an allogeneic stem cell transplant.

One notable feature of this cohort is that eight patients (89%) harbored nonsense germline NF1 variants. This case series highlights the emergence of synchronous or metachronous malignancies in children with NF1 and provides a rationale for heightened awareness of this phenomenon.

The consensus made 24 recommendations: gliomas in the optic pathway-6 statements, non-optical gliomas-2 statements, plexiform neurofibromas-5 statements, malignant peripheral nerve sheath tumors (MPNST)-6 statements, melanoma-1 statement, juvenile myelomonocytic leukemia (JMML)-1 statement, pheochromocytoma and paraganglioma-2 statements, and gastrointestinal stromal tumors (GIST)-1 statement. This consensus represents the first Brazilian recommendations on malignant and benign tumors in pediatric patients with NF1, providing a framework to standardize and optimize the clinical application for this disease.

CD34+CD38- JMML stem cells express a broad repertoire of NK cell ligands similar to that of acute myeloid leukemia stem cells; and CD33, CD44, and CD47 were expressed by both CD34+CD38- stem cells and CD34+CD38+ progenitors in JMML. This suggests that JMML may be responsive to NK cell-mediated activity, and that targeting CD33, CD44, or CD47 may facilitate eradication of JMML.

The identification of patients with NF1 and their interittent follow-up are important for the early detection of potential complications, especially tumorigenesis. This review aimed to summarize NF1-associated tumors in pediatric patients and recently developed targeted therapies for treating these tumors.

Importantly, NF1LOF cells displayed marked GM-CSF hypersensitivity in in vitro colony-forming unit assays - mirroring JMML; when transplanted into NSG-SGM3 mice, they caused rapid lethality, (median survival of 32 days), myeloid expansion, tissue infiltration (spleen, liver, and lungs), and specific upregulation of RAS/MAPK pathway and STAT5 genes, consistent with patient profiles. This first humanized NF1LOF mouse model recapitulates key JMML features, enabling investigation of disease mechanisms and targeted therapies.

P2, N=10, Active, not recruiting, National Cancer Institute (NCI) | Trial completion date: Oct 2025 --> Oct 2026

P1, N=140, Active, not recruiting, Incyte Corporation | Recruiting --> Active, not recruiting | N=231 --> 140

Specifically, the 20% of patients with highest BMP4 methylation had a 5-year DFS of 0.38, in contrast to 0.62 for the lowest 20% (p = 0.007). These findings highlight the potential of BMP4 methylation analysis as a complementary biomarker for JMML risk stratification, mirroring genome-wide methylation profiles known to associate with prognostic subgroups.

These findings support W&W as a viable alternative in up to 30% of JMML patients, potentially sparing them from HSCT-associated risks. Given the persistence of clonal hematopoiesis and the risk of extra-hematological complications, long-term monitoring remains essential.