Project 3: Contribution of inflammation and DNA damaging factors to clonal expansion and malignant transformation in a community cohort of older adults

Project Summary/Abstract Project 3 will test the hypothesis that modifiable risk factors, including inflammation and DNA-damaging factors, influence expansion of hematopoietic stem and progenitor cell (HSPC) clones with certain genetic mutations and their transformation to hematologic malignancy. We will identify modifiable risk factors associated with HSPC clonal expansion and malignant transformation in a prospective epidemiologic study of 9,513 persons (Black 27%, female 55%) now all >75 years old from ARIC, a long-standing community cohort study. We will use stored buffy coat for single cell DNA sequencing, and leverage completed peripheral blood leukocyte (PBL) whole exome sequencing (WES), methylation, and proteomic profiling. Aim 1 will determine long-term changes in clonal composition at the single-cell level with resources from Core A and identify inflammation and DNA damage- related factors associated with those changes. For 250 ARIC participants with ³1 clonal variant by WES at Time 1 or at Time 2 (20 years later) and/or hematologic malignancy after Time 2, we will measure individual leukocyte variant profiles at both times by single cell-DNA sequencing. By tracking individual clones at unprecedented resolution, we will assess clonal fitness and identify modifiable risk factors for expansion of clones with specific variants. Our study is the first to address change in clonal composition with hematologic malignancy in a community cohort. In Aim 2, we will evaluate the association of clonal composition, variant allele frequencies (VAFs), and changes of known myeloid malignancy driver genes and novel recurrent variants with hematologic malignancy risk over the span of two decades. In 9,513 participants, we will interrogate WES data at Time 1 and 2 (20 years apart) to identify novel recurrent variants with changing VAFs and classify participants by clonal composition and VAFs of known driver genes. For driver genes, we will estimate associations of change in clonal composition and VAF over time with hematologic malignancy risk. We project 341 first and 66 second primary hematologic malignancies within our cohort. Aim 3 will evaluate the association of inflammation- and DNA damage-related factors with hematologic malignancy risk in persons with detectable clonal variants. By Time 2, we expect >10% of participants will have clonal variants detectable by WES in driver and novel genes. We will estimate the association of modifiable factors with hematologic malignancy in persons with and without specific clonal variants over 30 years. Project 3 will identify drugs to test as interventions for clonal expansion and malignant transformation in mice in Projects 1 and 2. We also will test associations between altered cytokines and CpG methylation identified in Project 1 and determine whether mutations identified in Project 2 are observed in participants with DNA-damaging exposures. This Project will extensively utilize Core A for single-cell analysis and Core B for coordination. Identifying modifiable factors that drive clonal expansion and malignant transformation will provide opportunities to intercept clonal expansion and malignant transformation and enable early detection in persons at higher risk due to their genetic and modifiable risk factor profile.