Robust anti-myeloma effect of TAS0612, an RSK/AKT/S6K inhibitor, with venetoclax regardless of cytogenetic abnormalities

Multiple myeloma (MM) remains a difficult-to-treat disease even with the latest therapeutic advances due to the complex, overlapping, and heterogeneous cytogenetic, genetic, and molecular abnormalities. To address this challenging problem, we previously identified the universal and critical roles of RSK2 and AKT, the effector signaling molecules downstream of PDPK1, regardless of cytogenetic and genetic profiles. Based on this, in this study, we investigated the anti-myeloma potency of TAS0612, a triple inhibitor against RSK, including RSK2, AKT, and S6K. Treatment with TAS0612 exerted the anti-proliferative effect via cell cycle blockade and the induction of apoptosis in human myeloma-derived cell lines (HMCLs) with diverse cytogenetic and genetic profiles. Ex vivo treatment with TAS0612 also significantly reduced the viability of patient-derived primary myeloma cells with diverse cytogenetic profiles. TAS0612 simultaneously caused the upregulation of several tumor suppressor genes, modulated prognostic genes according to the MMRF CoMMpass data, and downregulated a series of Myc- and mTOR-related genes. Moreover, the combination of TAS0612 with venetoclax (VEN) showed the synergy in inducing apoptosis in HMCLs irrespective of the t(11;14) translocation status. TAS0612 alone and combined with VEN are new potent candidate therapeutic strategies for MM, regardless of cytogenetic/genetic profiles, facilitating its future clinical development.