Analysis and therapeutic targeting of the EP300 and CREBBP acetyltransferases in anaplastic large cell lymphoma and Hodgkin lymphoma

Anaplastic large cell lymphoma (ALCL) and classical Hodgkin lymphoma (HL) share a similar cytological and high surface expression of CD30, and novel therapeutic strategies are needed. The EP300 and CREBBP acetyltransferases play essential roles in the pathogenesis of non-Hodgkin B cell lymphoma, but their functions in ALCL and HL are unknown. In the current study, we investigated the physiological roles of EP300 and CREBBP in both ALCL and HL, and exploited the therapeutic potential of EP300/CREBBP small molecule inhibitors that target either the HAT or bromodomain activities. Our studies demonstrated distinct roles for EP300 and CREBBP in supporting the viability of ALCL and HL, which was bolstered by the transcriptome analyses. Specifically, EP300 but not CREBBP directly modulated the expression of oncogenic MYC/IRF4 network, surface receptor CD30, immunoregulatory cytokines IL10 and LTA, and immune checkpoint protein PD-L1. Importantly, EP300/CREBBP HAT inhibitor A-485 and bromodomain inhibitor CPI-637 exhibited strong activities against ALCL and HL in vitro and in xenograft mouse models, and inhibited PD-L1 mediated tumor immune escape. Thus, our studies revealed critical insights into the physiological roles of EP300/CREBBP in these lymphomas, and provided opportunities for developing novel strategies for both targeted and immune therapies.