Dpep, a Cell-Penetrating Peptide Targeting ATF5, CEBPB and CEBPD, Synergistically Combines with ABT-263 and Decitabine to Inhibit Cancer Cell Growth and Overcome Dpep Resistance

Dpep is a cell-penetrating peptide that targets transcription factors ATF5, CEBPB and CEBPD to selectively suppress growth and survival of diverse tumor cell types in vitro and in vivo. Due to these actions and its apparent safety, the peptide has potential as a cancer therapeutic. How Dpep might be combined with other anti-cancer agents to achieve synergistic efficacy and to overcome possible peptide resistance has not been assessed in depth. Based on prior work indicating that Dpep promotes apoptotic cancer cell death and up-regulates multiple pro-apoptotic and tumor suppressor genes, we studied combinations of Dpep with ABT-263, a pro-apoptotic BCL2 family inhibitor, and decitabine, a hypomethylating drug. Combining Dpep with each agent alone or together synergistically suppressed the growth of a range of solid and liquid tumor cell types. Moreover, the combinations synergistically inhibited the growth of cells lines that were selected either in vivo or in vitro for Dpep resistance. Finally, we tested the combination of Dpep with ABT-263 in a mouse melanoma xenograft model. The combination more effectively inhibited tumor growth than either agent alone and, in contrast to vehicle or ABT-263, produced a 40% durable survival rate. Taken together, these observations highlight potential drug partners for the therapeutic development of Dpep.