Diffuse Large B-cell lymphoma (DLBCL) is a common cancer in the US, causing tens of thousands of deaths each year and their incidence is on the rise. MicroRNA regulate the use of other genes and they are frequently mutated in human cancer One of these, miR-155 has been shown to be overproduced in several different lymphoma types, including cutaneous T-cell lymphoma (CTCL) and diffuse large B-cell lymphoma (DLBCL). This miRNA is an excellent target for therapy in DLBCL. miRagen Therapeutics, Inc. is currently testing the safety and efficacy of an inhibitor to miR-155 in patients with CTCL and DLBCL. This is an entirely novel class of drug, and as such requires some research into the parameters for successful delivery and monitoring. In this proposal we seek funding to allow studies that would support these clinical trials. We propose to identify biomarkers to help stratify patients to enroll in the clinical trial, biomarkers of response, and to determine the best route of delivery and the best source of tissue for miR-155 detection.