Ash has a significant history of research and accomplishments in cancer genomics, beginning with the original development of microarray gene expression profiling for cancer classification starting with lymphomas, and advancing to multiple tumor types. His group helped develop techniques for ultra-sensitive and non-invasive detection of tumor-derived cell-free DNA (CAPP-Seq), and for computational deconvolution of gene expression data for deciphering cellular heterogeneity in tumors including immune infiltration (CIBERSORT). His translational research effort is focused on attaining a more sophisticated understanding of the initiation, maintenance, and progression of tumors and their response to therapy toward improving current treatment strategies. In this effort, his group employs tools from functional genomics, computational biology, molecular genetics, and mouse models. Clinically, he is a practicing medical oncologist specializing in the care of patients with lymphoma, including diffuse large B-cell lymphomas (DLBCL), with his clinical research is focused on diagnostic, prognostic, and predictive markers and on translating discoveries from the laboratory to the clinic using cutting tools in data science.