Functional characterization and rational therapeutic targeting of 18q DNA copy number gains in diffuse large B-cell lymphoma

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Project Summary Diffuse large B-cell lymphoma (DLBCL) is the most common form lymphoma and is conventionally treated with a combination of chemotherapeutics with the anti-CD20 antibody, Rituximab. Although more than half of patients can be cured with this approach, the remainder have a dire prognosis with a short survival. Despite the variability in patient outcome, there are currently no routinely utilized molecular biomarkers that can be employed for risk stratification or to direct a specific therapy. That is, precision medicine does not currently exist for DLBCL. We have identified a genetic alteration on the q-arm of chromosome 18 (18q) that is associated with an aggressive subtype of DLBCL, and defined the TCF4 and BCL2 genes as critical targets at this locus. The BCL2 gene encodes an important oncogene that prevents cell death, and can be targeted with the inhibitor Venetoclax. The TCF4 gene encodes a transcription factor protein that we have found to drive key malignant properties of lymphoma, such as promoting the expression of the MYC oncogene and the B-cell receptor. In addition, we have defined a way to eliminate TCF4 expression using a novel type of protein-degrader molecules that are directed towards BET proteins. This therefore provides an exciting rational therapeutic avenue for targeting TCF4. We hypothesize that combining this with an inhibitor of BCL2 will target both genes that are activated by 18q alterations, and provide a precision medicine approach for treating this aggressive subset of DLBCL. Here, we are proposing to investigate the function of 18q alterations in DLBCL and validate the mechanism by which we believe this genetic event leads to lymphoma. We will also perform pre-clinical investigation of combinations of BET and BCL2 inhibitors for the specific therapeutic targeting of 18q alterations. Together, this work will advance our understanding of DLBCL disease biology and may lead to advances in precision medicine for this disease.