TERT promotor variant associated with poor clinical outcome in a patient with novel RBM15-MKL1 fusion-positive pediatric acute megakaryoblastic leukemia

Rare Hematologic Malignancies and Pre-Leukemic Entities in Children and Adolescents Young Adults

There are a variety of rare hematologic malignancies and germline predispositions syndromes that occur in children and adolescent young adults (AYAs). These entities are important to recognize, as an accurate diagnosis is essential for risk assessment, prognostication, and treatment. This descriptive review summarizes rare hematologic malignancies, myelodysplastic neoplasms, and germline predispositions syndromes that occur in children and AYAs. We discuss the unique biology, characteristic genomic aberrations, rare presentations, diagnostic challenges, novel treatments, and outcomes associated with these rare entities.

RBM15 condensates modulate m6A modification of STYK1 to promote tumorigenesis

RBM15 expression is recurrently upregulated in several types of malignant tissues, and its high expression level is typically associated with poor prognosis. However, whether and how RBM15 is involved in the tumor progression remains unclear. In this study, we found that overexpressing RBM15 in NIH3T3 cells was able to enhance proliferation rate in vitro and induced subcutaneous tumor formation in vivo. Moreover, we imaged the subcellular localization of RBM15 with our home-built structured illumination super-resolution microscopy, and revealed that RBM15 formed substantial condensates dispersed in the nucleus, undergoing dynamic fusion and fission activities. These condensates were partially colocalized with m⁶A-modified transcripts in the nucleus. In addition, we confirmed that RBM15 formed “liquid-like” droplets in a protein/salt concentration-dependent manner in vitro, and the addition of RNA further enhanced its phase-separation propensity. To identify downstream targets of RBM15, we performed meRIP-seq and RNA-seq, revealing that RBM15 preferentially bound to and promoted the m⁶A modification on the mRNA of Serine/threonine/tyrosine kinase 1 (STYK1), thereby enhancing its stability. The upregulated STYK1 expression caused MAPK hyperactivation, thereby leading to oncogenic transformation of NIH3T3 cells.

What Is the Role of HSCT in Philadelphia-Chromosome-Positive and Philadelphia-Chromosome-Like ALL in the Tyrosine Kinase Inhibitor Era?

Previously, the outcome of paediatric Philadelphia-chromosome-positive (Ph+) ALL treated with conventional chemotherapy alone was poor, necessitating the use of haematopoietic stem cell transplantation (HSCT) for the best outcomes. The recent addition of tyrosine kinase inhibitors (TKIs) alongside the chemotherapy regimens for Ph+ ALL has markedly improved outcomes, replacing the need for HSCT for lower risk patients. An additional poor prognosis group of Philadelphia-chromosome-like (Ph-like) ALL has also been identified. This group also can be targeted by TKIs in combination with chemotherapy, but the role of HSCT in this population is not clear. The impact of novel targeted immunotherapies (chimeric antigen receptor T cells and bispecific or drug-conjugated antibodies) has improved the outcome of patients, in combination with chemotherapy, and made the role of HSCT as the optimal curative therapy for Ph+ ALL and Ph-like ALL less clear. The prognosis of patients with Ph+ ALL and persistent minimal residual disease (MRD) at the end of consolidation despite TKI therapy or with additional genetic risk factors remains inferior when HSCT is not used. For such high-risk patients, HSCT using total-body-irradiation-containing conditioning is currently recommended. This review aims to provide an update on the current and future role of HSCT for Ph+ ALL and addresses key questions related to the management of these patients, including the role of HSCT in first complete remission, MRD evaluation and related actions post HSCT, TKI usage post HSCT, and the putative role of HSCT in Ph-like ALL.