Investigating and targeting NSD2 mutation-driven leukemia transformation - PROJECT SUMMARY/ABSTRACT Acute lymphoblastic leukemia (ALL) is the most common childhood cancer and remains a leading cause of cancer-related mortality, particularly due to relapse. Mutations in NSD2 (also called WHSC1 and MMSET), a histone methyltransferase, are frequently found in relapsed B-cell ALL (B-ALL), especially in cases with the ETV6::RUNX1 fusion gene. The heterozygous p.E1099K point mutation is the most prevalent NSD2 mutation and leads to increased H3K36me2 and decreased H3K27me3. These mutations alter chromatin structure, disrupting gene expression and driving processes such as glucocorticoid resistance and central nervous system infiltration. However, how NSD2 mutations initiate leukemia transformation remains unclear. We hypothesize that NSD2-driven changes in histone modifications alter gene transcription in B cells, leading to leukemia transformation. To address this, we generated a novel conditional NSD2 p.E1099K mutation knock-in mouse model and demonstrated that NSD2 mutations alone can drive B-cell leukemia. This project will further investigate how NSD2 mutations in hematopoietic stem cells promote lymphocyte transformation and explore their role in the context of the ETV6::RUNX1 fusion gene, which is associated with the most common childhood ALL subtype. We will employ cutting-edge techniques such as single-cell RNA sequencing (scRNA-Seq), ATAC- Seq, and CUT&RUN to analyze epigenetic and transcriptional changes caused by NSD2 mutations. Finally, we will evaluate a novel NSD2 inhibitor in both mouse models and human cell line-derived xenograft (CDX) and patient-derived xenograft (PDX) models as a potential treatment for relapsed ALL. The specific aims are: 1) Determine the mechanisms by which NSD2 mutations drive leukemia transformation; 2) Evaluate the role of NSD2 mutations in driving ETV6::RUNX1 leukemia transformation; 3) Target NSD2 mutation-driven leukemia transformation. The outcomes of this research will provide a comprehensive understanding of how NSD2 mutations contribute to leukemia transformation and may lead to the development of new therapeutic strategies. The novel NSD2 inhibitor holds promise for treating NSD2-mutant ALL, offering potential improvements in survival for relapsed patients. Our mouse models also provide an important platform for further research and therapeutic testing in blood cancers.
