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T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematopoietic neoplasm resulting from the malignant transformation of T-cell progenitors. While activating NOTCH1mutations are the dominant genetic drivers of T-ALL, epigenetic dysfunction plays a central role in the pathology of T-ALL and can provide alternative mechanisms to oncogenesis in lieu of or in combination with genetic mutations. The histone demethylase enzyme KDM6A(UTX) is also recurrently mutated in T-ALL patients and functions as a tumor suppressor. However, its gene paralog, KDM6B(JMJD3), is never mutated and can be significantly overexpressed, suggesting it may be necessary for sustaining the disease. Here, we used mouse and human T-ALL models to show that KDM6Bis required for T-ALL development and maintenance. Using NOTCH1gain-of-function retroviral models, mouse cells genetically deficient for Kdm6bwere unable to propagate T-ALL. Inactivating KDM6Bin human T-ALL patient cells by CRISPR/Cas9 showed KDM6B-targeted cells were significantly outcompeted over time. The dependence of T-ALL cells on KDM6Bwas proportional to the oncogenic strength of NOTCH1mutation, with KDM6B required to prevent stress-induced apoptosis from strong NOTCH1 signaling. These studies identify a crucial role for KDM6Bin sustaining NOTCH1-driven T-ALL and implicate KDM6B as a novel therapeutic target in these patients.

Acquired mutations are pervasive across normal tissues. However, understanding of the processes that drive transformation of certain clones to cancer is limited. Here we study this phenomenon in the context of clonal hematopoiesis (CH) and the development of therapy-related myeloid neoplasms (tMNs). We find that mutations are selected differentially based on exposures. Mutations in ASXL1are enriched in current or former smokers, whereas cancer therapy with radiation, platinum and topoisomerase II inhibitors preferentially selects for mutations in DNA damage response genes (TP53, PPM1D, CHEK2). Sequential sampling provides definitive evidence that DNA damage response clones outcompete other clones when exposed to certain therapies. Among cases in which CH was previously detected, the CH mutation was present at tMN diagnosis. We identify the molecular characteristics of CH that increase risk of tMN. The increasing implementation of clinical sequencing at diagnosis provides an opportunity to identify patients at risk of tMN for prevention strategies.

The JAK2V617Fvariant is an acquired somatic mutation recurrently found in myeloproliferative neoplasm (MPN) patients and is used as a diagnostic marker. While considered a strong MPN driver mutation, this variant is sometimes absent in secondary acute myeloid leukemia (sAML) samples which transform from antecedent JAK2-mutant MPNs. The transformative evolution of MPN to sAML is thought to be driven by acquisition of additional genetic mutations affecting epigenetic modifiers (e.g. TET2), tumor suppressor genes (e.g. TP53), and splicing regulation, but the contribution and sequence of onset for these specific genetic events is not well understood. It is currently unknown why or how patients with a JAK2-mutant MPN may develop a JAK2wild-type sAML. This transformation sequence is coupled with very limited treatment options and a survival of less than 6-months. Elucidating the evolutionary trajectory of secondary leukemic mutation occurrence is paramount for disease monitoring and early detection.

Every tissue in the human body becomes a mosaic of somatic mutations throughout life. Each cell in the body contains a record of the genetic alterations occurring from conception until that individual cell came into existence through cell division. Most of these changes are benign, but cells with alterations that endow a selective advantage can preferentially divide and expand. Already, this process has been described in a diverse set of phenotypically normal tissues including skin, esophagus and colon (Colom et al., 2021; Lee-Six et al., 2019; Martincorena et al., 2015). In these solid organs, clonal mutations are geographically constrained within contiguous regions of tissue. In the blood, these somatic mutations are termed clonal hematopoiesis (CH) (Steensma et al., 2015). Previous work has extensively characterized the burden of CH in humans, showing an increased prevalence with age and increased risk for hematologic malignancy and all-cause mortality (Genovese et al., 2014; Jaiswal et al., 2014; Young et al., 2016; Young et al., 2019). Despite our detailed understanding of CH in the blood, little is known about how these hematopoietic clones exist in the bone marrow (BM) and how they interact with the BM niche.

Acute myeloid leukemia (AML) is an aggressive blood cancer diagnosed in ∼120,000 individuals worldwide each year. During treatment for AML, detecting residual disease is essential for prognostication and treatment decision-making. Currently, methods for detecting residual AML are limited to identifying ∼1:100-1:1,000 leukemic cells (morphology, DNA sequencing) or difficult to implement (flow cytometry). AML arising after chemotherapy or radiation exposure is termed therapy-related AML (t-AML) and is exceptionally aggressive and treatment resistant. T-AML is often driven by oncogenic fusions resulting from prior treatments that introduce double-strand DNA breaks. The most common t-AML-associated translocations affect the histone-lysine N-methyltransferase 2A (KMT2A). There are at least 80 known KMT2Afusion partners, but about 80% of fusions involve just five partners — AF9, AF6, AF4, ELLand ENL. Here we present a novel droplet digital PCR (ddPCR) assay targeting the most common KMT2A-rearrangements to enable detection of rare AML cells harboring these fusions. This assay was benchmarked in cells lines and patient samples harboring oncogenic KMT2Afusions and demonstrated a limit of detection of approximately 1:1,000,000 cells. Future application of this assay could improve disease detection and treatment decision-making for t-AML patients with KMT2Afusions and detect pre-malignant oncogenic fusions in at-risk individuals after chemotherapy exposure.

OBJECTIVE: To determine the prevalence of oral candidiasis and multiple oral Candida infections in patients with primary Sjögren’s syndrome (SS), and the clinical and drug susceptibility profile. METHODS: Thirty patients with primary SS were enrolled in our study. The diagnosis of oral candidiasis was based on the clinical manifestation, and confirmed by a concentrated rinse culture. Candida spp. assessment was accomplished using standard methods: Sabouraud dextrose agar with 50 mg/l chloramphenicol and CHROMagar were used for the rapid screening of clinical species, followed by the API 20C system for further species identification. In vitro antifungal drug susceptibility of Candida isolates was determined by the minimal inhibitory concentrations. RESULTS: In our study, 87% (26/30) of subjects had oral candidiasis, in which 42% (11/26) had multiple Candida spp. infection. Although C. albicans remains the predominant isolate, other rare species such as C. tropicalis, C. glabrata, C. parapsilosis, and C. krusei were present, alone or in combination. Chronic atrophic candidiasis is the most common clinical type of oral candidiasis in patients with SS. The susceptibilities of the 44 Candida isolates to 7 antifungal agents varied dramatically. The resistance to azoles was remarkable, and the phenomenon of cross-resistance between itraconazole and fluconazole was observed. CONCLUSION: Patients with primary SS carry a high risk of oral candidiasis and a high frequency of multiple Candida infections. The azole resistance patterns of Candida spp. support the necessity for drug susceptibility testing as a routine procedure for patients with oral Candida infections.

Clonal hematopoiesis is a recognized feature of the aging hematopoietic compartment (Busque L, et al., Blood2009). Recent next-generation sequencing (NGS) studies have identified the epigenetic regulators DNMT3Aand TET2as genes mutated frequently in clonal hematopoiesis (Busque L, et al., Nat Genet2012; Xie M, et al., Nat Med2014; Jaiswal S, et al., NEJM2014; Genovese G, et al. NEJM2014). While intrinsically benign, these hematopoietic clones-termed clonal hematopoiesis of indeterminate potential (CHIP)-are detected in approximately 10% of individuals 70 years of age and associated with an increased risk of hematological malignancy and all-cause mortality (Jaiswal S, et al., NEJM2014; Genovese G, et al., NEJM2014; Steensma DP, et al., Blood2015).