Figure 6: Induction of interferon-responsive and antigen presentation genes in DLBCL cell lines and patient-derived xenograft.

A) A heat map shows significantly up-regulated (above) and down-regulated (below) genes in BRD3308-treated DLBCL cell lines that are CREBBP wild-type (OCI-Ly1) or mutant (OCI-Ly19 and OZ), expressed as a log2 ratio to vehicle control treated cells. The observed changes were consistent between wild-type and mutant cell lines, and included up-regulation of interferon-responsive and antigen presentation genes. B) MHC class II was assessed on vehicle control (left) and BRD3308 treated (25mg/kg, right) tumors from a CREBBP R1446C mutant PDX model, showing a visible increase in expression in the BRD3308-treated tumors. These images are representative of 4 tumors per group. C) An MHC class II-negative DLBCL patient derived xenograft model was treated in vivo with either 25mg/kg or 50mg/kg of BRD3308. Immunohistochemical staining was performed for MHC class II, revealing a robust induction of MHC class II expression that was relative to the dose of treatment. These images are representative of 6 tumors per group. D) qPCR was used to validate the gene expression changes of select interferon-responsive genes following BRD3308 treatment across an extended panel of CREBBP wild-type and mutant DLBCL cell lines. These genes were uniformly increased in both genetic contexts, but with a higher magnitude of increase in CREBBP mutant cell lines. One-tailed Students T-test *P<0.05, **P<0.01, **P<0.001. E) The induction of MHC class II expression by BRD3308 was measured in an extended panel of DLBCL cell lines by flow cytometry. Data are plotted as a fold-change of the mean fluorescence intensity (MFI) of HLA-DR in BRD3308-treated vs control-treated cells. We observed uniformly increased MHC class II expression in all cell lines, but with higher magnitude in CREBBP mutants.