TET2 somatic copy number alterations and allelic imbalances in chronic myelomonocytic leukemia

PHF6 mutations in chronic myelomonocytic leukemia identify a unique subset of patients with distinct phenotype and superior prognosis

The current study was inspired by observations from exploratory analyses of an institutional cohort with chronic myelomonocytic leukemia (CMML; N = 398) that revealed no instances of blast transformation in the seven patients with plant homeodomain finger protein 6 (PHF6) mutation (PHF6MUT). A subsequent Mayo Clinic enterprise-wide database search identified 28 more cases with PHF6MUT. Compared with their wild-type PHF6 counterparts (PHF6WT; N = 391), PHF6MUT cases (N = 35) were more likely to co-express TET2 (89% vs. 45%; p < .01), RUNX1 (29% vs. 14%; p = .03), CBL (14% vs. 2%; p < .01), and U2AF1 (17% vs. 6%; p = .04) and less likely SRSF2 (23% vs. 45%; p < .01) mutation. They were also more likely to display loss of Y chromosome (LoY; 21% vs. 2%; p < .01) and platelets <100 × 109/L (83% vs. 51%; p < .01). Multivariable analysis identified PHF6MUT (HR 0.28, 95% CI 0.15-0.50) and DNMT3AMUT (HR 5.8, 95% CI 3.3-10.5) as the strongest molecular predictors of overall survival. The same was true for blast transformation-free survival with corresponding HR (95% CI) of 0.08 (0.01-0.6) and 9.5 (3.8-23.5). At median 20 months follow-up, blast transformation was documented in none of the 33 patients with PHF6MUT/DNMT3AWT but in 6 (32%) of 19 with DNMT3AMUT and 74 (20%) of 374 with PHF6WT/DNMT3AWT (p < .01). The specific molecular signatures sustained their significant predictive performance in the context of the CMML-specific molecular prognostic model (CPSS-mol). PHF6MUT identifies a unique subset of patients with CMML characterized by thrombocytopenia, higher prevalence of LoY, and superior prognosis.

Chronic myelomonocytic leukemia: 2024 update on diagnosis, risk stratification and management

DISEASE OVERVIEW

Chronic myelomonocytic leukemia (CMML) is a clonal hematopoietic stem cell disorder with overlapping features of myelodysplastic syndromes and myeloproliferative neoplasms, characterized by prominent monocytosis and an inherent risk for leukemic transformation (~15%-20% over 3-5 years).

DIAGNOSIS

Newly revised diagnostic criteria include sustained (>3 months) peripheral blood (PB) monocytosis (≥0.5 × 109/L; monocytes ≥10% of leukocyte count), consistent bone marrow (BM) morphology, <20% BM or PB blasts (including promonocytes), and cytogenetic or molecular evidence of clonality. Cytogenetic abnormalities occur in ~30% of patients, while >95% harbor somatic mutations: TET2 (~60%), SRSF2 (~50%), ASXL1 (~40%), RAS pathway (~30%), and others. The presence of ASXL1 and DNMT3A mutations and absence of TET2 mutations negatively impact overall survival (ASXL1WT/TET2MT genotype being favorable).

RISK STRATIFICATION

Several risk models serve similar purposes in identifying high-risk patients that are considered for allogeneic stem cell transplant (ASCT) earlier than later. Risk factors in the Mayo Molecular Model (MMM) include presence of truncating ASXL1 mutations, absolute monocyte count >10 × 109/L, hemoglobin <10 g/dL, platelet count <100 × 109/L, and the presence of circulating immature myeloid cells; the resulting 4-tiered risk categorization includes high (≥3 risk factors), intermediate-2 (2 risk factors), intermediate-1 (1 risk factor), and low (no risk factors); the corresponding median survivals were 16, 31, 59, and 97 months. CMML is also classified as being "myeloproliferative (MP-CMML)" or "myelodysplastic (MD-CMML)," based on the presence or absence of leukocyte count of ≥13 × 109/L.

TREATMENT

ASCT is the only treatment modality that secures cure or long-term survival and is appropriate for MMM high/intermediate-2 risk disease. Drug therapy is currently not disease-modifying and includes hydroxyurea and hypomethylating agents; a recent phase-3 study (DACOTA) comparing hydroxyurea and decitabine, in high-risk MP-CMML, showed similar overall survival at 23.1 versus 18.4 months, respectively, despite response rates being higher for decitabine (56% vs. 31%).

UNIQUE DISEASE ASSOCIATIONS

These include systemic inflammatory autoimmune diseases, leukemia cutis and lysozyme-induced nephropathy; the latter requires close monitoring of renal function during leukocytosis and is a potential indication for cytoreductive therapy.

Methane Emissions Show Recent Decline but Strong Seasonality in Two US Northeastern Cities

Urban methane emissions estimated using atmospheric observations have been found to exceed estimates derived by using traditional inventory methods in several northeastern US cities. In this work, we leveraged a nearly five-year record of observations from a dense tower network coupled with a newly developed high-resolution emissions map to quantify methane emission rates in Washington, DC, and Baltimore, Maryland. Annual emissions averaged over 2018-2021 were 80.1 [95% CI: 61.2, 98.9] Gg in the Washington, DC urban area and 47.4 [95% CI: 35.9, 58.5] Gg in the Baltimore urban area, with a decreasing trend of approximately 4-5% per year in both cities. We also find wintertime emissions 44% higher than summertime emissions, correlating with natural gas consumption. We further attribute a large fraction of total methane emissions to the natural gas sector using a least-squares regression on our spatially resolved estimates, supporting previous findings that natural gas systems emit the plurality of methane in both cities. This study contributes to the relatively sparse existing knowledge base of urban methane emissions sources and variability, adding to our understanding of how these emissions change in time and providing evidence to support efforts to mitigate natural gas emissions.