Exploiting the pro-apoptotic function of NOXA as a therapeutic modality in cancer.

INTRODUCTION: Direct targeting of Bcl-2 members for therapeutic purposes in cancer has become a clinical reality with the FDA approval of ABT-199/Venetoclax. Other highly specific BH3-mimetics are in pre-clinical development. Understanding the functional interactions among the Bcl-2 family is of prime importance to fully exploit their potential. NOXA is considered a rather weak BH3-only member but it has unexplored potential in various settings, which are of relevance in cancer. NOXA is best known as a selective inhibitor of MCL1, itself overexpressed in many cancers, and this protein pair forms an important rheostat in many forms of cell stress. Areas covered: We summarize the distinct pathways that induce NOXA RNA and protein, and how this may be exploited in solid and hematopoietic cancers, with a focus on multiple myeloma and chronic lymphocytic leukemia. Expert opinion: The therapeutic potential to induce NOXA is not yet fully explored nor exploited, and we suggest 1) areas that require further fundamental investigation, including replicative stress and epigenetics, 2) areas where translation to therapeutic application seems more imminent (ER stress, ROS, inhibition of NOXA degradation) 3) a complementary approach to inducing NOXA by direct targeting of MCL1 via the novel BH3 mimetic S63845 and similar compounds.